Mar. 31, 2026 |
| Prospectus Summary | MFS Alabama Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS Alabama Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer,
borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions
of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental,
public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults
during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of
a debt instrument. The credit quality of, and the ability to pay
principal and interest when due by, an issuer of a municipal instrument depends on the credit quality
of the entity supporting the municipal instrument, how essential any services supported by the municipal
instrument are, the sufficiency of any revenues or taxes that support the municipal instrument, and/or
the willingness or ability of the appropriate government entity to approve any appropriations necessary
to support the municipal instrument. In addition, the price of a municipal instrument also depends on
its credit quality and ability to meet the credit support obligations of any insurer or other entity
providing credit support to a municipal instrument. Below investment
grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”)
can involve a substantially greater risk of default or can already be in default, and their values can
decline significantly. Below investment grade quality debt instruments are regarded as having predominantly
speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive
to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments.
|
| Focus Risk |
Focus
Risk: The fund’s performance will be closely tied to the economic, political, environmental,
and public health conditions in Alabama, and can be more volatile than the performance of a more geographically
diversified fund. In addition, the fund's performance can also be tied to the economic and political
conditions of other states and U.S. territories and possessions in which the fund is invested. These
conditions may include constitutional or statutory limits on an issuer’s ability to raise revenues
or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes
in the credit quality of municipal issuers in the state, other states, or U.S. territories and possessions. If MFS invests a significant percentage of the fund's assets in a single issuer
or small number of issuers, the fund’s performance could be more volatile than the performance of more
diversified funds.
|
| Municipal Risk |
Municipal Risk: The price
of a municipal instrument can be volatile and significantly affected by adverse tax changes or court
rulings, legislative or political changes, changes in specific or general market and economic conditions
and developments, and the financial condition of municipal issuers and insurers. Because many municipal
instruments are issued to finance similar projects, conditions in certain industries can significantly
affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades
or defaults during economic downturns or similar periods of economic stress, which in turn could affect
the market values and marketability of many or all municipal obligations of issuers in a state, U.S.
territory, or possession. In addition, because some
municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated
with investments in such municipal securities could increase if the banking or financial sector suffers
an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded
or at risk of being downgraded by a national rating organization. If such events occur, the value of
the security could decrease or the value could be lost entirely, and it may be difficult or impossible
to sell the security at the time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS Arkansas Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS Arkansas Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer,
borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions
of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental,
public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults
during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of
a debt instrument. The credit quality of, and the ability to pay
principal and interest when due by, an issuer of a municipal instrument depends on the credit quality
of the entity supporting the municipal instrument, how essential any services supported by the municipal
instrument are, the sufficiency of any revenues or taxes that support the municipal instrument, and/or
the willingness or ability of the appropriate government entity to approve any appropriations necessary
to support the municipal instrument. In addition, the price of a municipal instrument also depends on
its credit quality and ability to meet the credit support obligations of any insurer or other entity
providing credit support to a municipal instrument. Below investment
grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”)
can involve a substantially greater risk of default or can already be in default, and their values can
decline significantly. Below investment grade quality debt instruments are regarded as having predominantly
speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive
to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments.
|
| Focus Risk |
Focus
Risk: The fund’s performance will be closely tied to the economic, political, environmental,
and public health conditions in Arkansas, and can be more volatile than the performance of a more geographically
diversified fund. In addition, the fund's performance can also be tied to the economic and political
conditions of other states and U.S. territories and possessions in which the fund is invested. These
conditions may include constitutional or statutory limits on an issuer’s ability to raise revenues
or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes
in the credit quality of municipal issuers in the state, other states, or U.S. territories and possessions. If MFS invests a significant percentage of the fund's assets in a single issuer
or small number of issuers, the fund’s performance could be more volatile than the performance of more
diversified funds.
|
| Municipal Risk |
Municipal Risk: The price
of a municipal instrument can be volatile and significantly affected by adverse tax changes or court
rulings, legislative or political changes, changes in specific or general market and economic conditions
and developments, and the financial condition of municipal issuers and insurers. Because many municipal
instruments are issued to finance similar projects, conditions in certain industries can significantly
affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades
or defaults during economic downturns or similar periods of economic stress, which in turn could affect
the market values and marketability of many or all municipal obligations of issuers in a state, U.S.
territory, or possession. In addition, because some
municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated
with investments in such municipal securities could increase if the banking or financial sector suffers
an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded
or at risk of being downgraded by a national rating organization. If such events occur, the value of
the security could decrease or the value could be lost entirely, and it may be difficult or impossible
to sell the security at the time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS California Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS California Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying
collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry,
political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments
may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic
stress, which in turn could negatively affect the market value and liquidity of a debt instrument. The credit quality of, and the ability to pay principal and interest when due
by, an issuer of a municipal instrument depends on the credit quality of the entity supporting the municipal
instrument, how essential any services supported by the municipal instrument are, the sufficiency of
any revenues or taxes that support the municipal instrument, and/or the willingness or ability of the
appropriate government entity to approve any appropriations necessary to support the municipal instrument.
In addition, the price of a municipal instrument also depends on its credit quality and ability to meet
the credit support obligations of any insurer or other entity providing credit support to a municipal
instrument. Below investment grade quality debt instruments
(commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially
greater risk of default or can already be in default, and their values can decline significantly. Below
investment grade quality debt instruments are regarded as having predominantly speculative characteristics.
Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer,
or the market or economy in general, than higher quality debt instruments.
|
| Focus Risk |
Focus Risk:
The fund’s performance will be closely tied to the economic, political, environmental,
and public health conditions in California, and can be more volatile than the performance of a more geographically
diversified fund. In addition, the fund's performance can also be tied to the economic and political
conditions of other states and U.S. territories and possessions in which the fund is invested. These
conditions may include constitutional or statutory limits on an issuer’s ability to raise revenues
or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes
in the credit quality of municipal issuers in the state, other states, or U.S. territories and possessions. If MFS invests a significant percentage of the fund's assets in a single issuer
or small number of issuers, the fund’s performance could be more volatile than the performance of more
diversified funds.
|
| Municipal Risk |
Municipal Risk: The price
of a municipal instrument can be volatile and significantly affected by adverse tax changes or court
rulings, legislative or political changes, changes in specific or general market and economic conditions
and developments, and the financial condition of municipal issuers and insurers. Because many municipal
instruments are issued to finance similar projects, conditions in certain industries can significantly
affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades
or defaults during economic downturns or similar periods of economic stress, which in turn could affect
the market values and marketability of many or all municipal obligations of issuers in a state, U.S.
territory, or possession. In addition, because some
municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated
with investments in such municipal securities could increase if the banking or financial sector suffers
an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded
or at risk of being downgraded by a national rating organization. If such events occur, the value of
the security could decrease or the value could be lost entirely, and it may be difficult or impossible
to sell the security at the time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS Georgia Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS Georgia Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer,
borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions
of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental,
public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults
during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of
a debt instrument. The credit quality of, and the ability to pay
principal and interest when due by, an issuer of a municipal instrument depends on the credit quality
of the entity supporting the municipal instrument, how essential any services supported by the municipal
instrument are, the sufficiency of any revenues or taxes that support the municipal instrument, and/or
the willingness or ability of the appropriate government entity to approve any appropriations necessary
to support the municipal instrument. In addition, the price of a municipal instrument also depends on
its credit quality and ability to meet the credit support obligations of any insurer or other entity
providing credit support to a municipal instrument. Below investment
grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”)
can involve a substantially greater risk of default or can already be in default, and their values can
decline significantly. Below investment grade quality debt instruments are regarded as having predominantly
speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive
to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments.
|
| Focus Risk |
Focus
Risk: The fund’s performance will be closely tied to the economic, political, environmental,
and public health conditions in Georgia, and can be more volatile than the performance of a more geographically
diversified fund. In addition, the fund's performance can also be tied to the economic and political
conditions of other states and U.S. territories and possessions in which the fund is invested. These
conditions may include constitutional or statutory limits on an issuer’s ability to raise revenues
or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes
in the credit quality of municipal issuers in the state, other states, or U.S. territories and possessions. If MFS invests a significant percentage of the fund's assets in a single issuer
or small number of issuers, the fund’s performance could be more volatile than the performance of more
diversified funds.
|
| Municipal Risk |
Municipal Risk: The price
of a municipal instrument can be volatile and significantly affected by adverse tax changes or court
rulings, legislative or political changes, changes in specific or general market and economic conditions
and developments, and the financial condition of municipal issuers and insurers. Because many municipal
instruments are issued to finance similar projects, conditions in certain industries can significantly
affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades
or defaults during economic downturns or similar periods of economic stress, which in turn could affect
the market values and marketability of many or all municipal obligations of issuers in a state, U.S.
territory, or possession. In addition, because some
municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated
with investments in such municipal securities could increase if the banking or financial sector suffers
an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded
or at risk of being downgraded by a national rating organization. If such events occur, the value of
the security could decrease or the value could be lost entirely, and it may be difficult or impossible
to sell the security at the time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS Maryland Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS Maryland Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal
Risks As with any mutual fund, the fund may not achieve its objective
and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit
and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental
agency. The principal risks of investing in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the fund may not achieve its objective
and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment in the fund is not a bank deposit
and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental
agency.
|
| Investment Selection Risk |
Investment
Selection Risk: MFS' investment analysis and its selection of investments
may not produce the intended results and/or can lead to an investment focus that results in the fund
underperforming other funds with similar investment strategies and/or underperforming the markets in
which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the
fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market
Risk: Debt markets can be volatile and can decline significantly in response to changes
in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical,
environmental, public health, and other conditions. These conditions can affect a single instrument,
issuer, or borrower, a particular type of instrument, issuer, or borrower, a segment of the debt markets
or the debt markets generally. Certain events can have a dramatic adverse effect on debt markets and
may lead to periods of high volatility and reduced liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest Rate Risk: In general,
the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest
rate risk is generally greater for instruments with longer maturities or durations, or that do not pay
current interest.
|
| Credit Risk |
Credit Risk: The
price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty,
or other entity responsible for payment, or underlying collateral or assets and the terms of the instrument.
The price of a debt instrument can decline in response to changes in, or perceptions of, the financial
condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets,
or changes in, or perceptions of, specific or general market, economic, industry, political, regulatory,
geopolitical, environmental, public health, and other conditions. Debt instruments may be more susceptible
to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of
a debt instrument. The credit quality of, and the ability to pay
principal and interest when due by, an issuer of a municipal instrument depends on the credit quality
of the entity supporting the municipal instrument, how essential any services supported by the municipal
instrument are, the sufficiency of any revenues or taxes that support the municipal instrument, and/or
the willingness or ability of the appropriate government entity to approve any appropriations necessary
to support the municipal instrument. In addition, the price of a municipal instrument also depends on
its credit quality and ability to meet the credit support obligations of any insurer or other entity
providing credit support to a municipal instrument. Below investment
grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”)
can involve a substantially greater risk of default or can already be in default, and their values can
decline significantly. Below investment grade quality debt instruments are regarded as having predominantly
speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive
to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments.
|
| Focus Risk |
Focus
Risk: The fund’s performance will be closely tied to the economic, political, environmental,
and public health conditions in Maryland, and can be more volatile than the performance of a more geographically
diversified fund. In addition, the fund's performance can also be tied to the economic and political
conditions of other states and U.S. territories and possessions in which the fund is invested. These
conditions may include constitutional or statutory limits on an issuer’s ability to raise revenues
or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes
in the credit quality of municipal issuers in the state, other states, or U.S. territories and possessions. If MFS invests a significant percentage of the fund's assets in a single issuer
or small number of issuers, the fund’s performance could be more volatile than the performance of more
diversified funds.
|
| Municipal Risk |
Municipal Risk: The price
of a municipal instrument can be volatile and significantly affected by adverse tax changes or court
rulings, legislative or political changes, changes in specific or general market and economic conditions
and developments, and the financial condition of municipal issuers and insurers. Because many municipal
instruments are issued to finance similar projects, conditions in certain industries can significantly
affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades
or defaults during economic downturns or similar periods of economic stress, which in turn could affect
the market values and marketability of many or all municipal obligations of issuers in a state, U.S.
territory, or possession. In addition, because some
municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated
with investments in such municipal securities could increase if the banking or financial sector suffers
an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded
or at risk of being downgraded by a national rating organization. If such events occur, the value of
the security could decrease or the value could be lost entirely, and it may be difficult or impossible
to sell the security at the time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS Massachusetts Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS Massachusetts Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer,
borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions
of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental,
public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults
during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of
a debt instrument. The credit quality of, and the ability to pay
principal and interest when due by, an issuer of a municipal instrument depends on the credit quality
of the entity supporting the municipal instrument, how essential any services supported by the municipal
instrument are, the sufficiency of any revenues or taxes that support the municipal instrument, and/or
the willingness or ability of the appropriate government entity to approve any appropriations necessary
to support the municipal instrument. In addition, the price of a municipal instrument also depends on
its credit quality and ability to meet the credit support obligations of any insurer or other entity
providing credit support to a municipal instrument. Below investment
grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”)
can involve a substantially greater risk of default or can already be in default, and their values can
decline significantly. Below investment grade quality debt instruments are regarded as having predominantly
speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive
to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments.
|
| Focus Risk |
Focus
Risk: The fund’s performance will be closely tied to the economic, political, environmental,
and public health conditions in Massachusetts, and can be more volatile than the performance of a more
geographically diversified fund. In addition, the fund's performance can also be tied to the economic
and political conditions of other states and U.S. territories and possessions in which the fund is invested.
These conditions may include constitutional or statutory limits on an issuer’s ability to raise revenues
or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes
in the credit quality of municipal issuers in the state, other states, or U.S. territories and possessions. If MFS invests a significant percentage of the fund's assets in a single issuer
or small number of issuers, the fund’s performance could be more volatile than the performance of more
diversified funds.
|
| Municipal Risk |
Municipal Risk: The price
of a municipal instrument can be volatile and significantly affected by adverse tax changes or court
rulings, legislative or political changes, changes in specific or general market and economic conditions
and developments, and the financial condition of municipal issuers and insurers. Because many municipal
instruments are issued to finance similar projects, conditions in certain industries can significantly
affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades
or defaults during economic downturns or similar periods of economic stress, which in turn could affect
the market values and marketability of many or all municipal obligations of issuers in a state, U.S.
territory, or possession. In addition, because some
municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated
with investments in such municipal securities could increase if the banking or financial sector suffers
an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded
or at risk of being downgraded by a national rating organization. If such events occur, the value of
the security could decrease or the value could be lost entirely, and it may be difficult or impossible
to sell the security at the time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS Mississippi Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS Mississippi Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal
Risks As with any mutual fund, the fund may not achieve its objective
and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit
and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental
agency. The principal risks of investing in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the fund may not achieve its objective
and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment in the fund is not a bank deposit
and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental
agency.
|
| Investment Selection Risk |
Investment
Selection Risk: MFS' investment analysis and its selection of investments
may not produce the intended results and/or can lead to an investment focus that results in the fund
underperforming other funds with similar investment strategies and/or underperforming the markets in
which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the
fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market
Risk: Debt markets can be volatile and can decline significantly in response to changes
in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical,
environmental, public health, and other conditions. These conditions can affect a single instrument,
issuer, or borrower, a particular type of instrument, issuer, or borrower, a segment of the debt markets
or the debt markets generally. Certain events can have a dramatic adverse effect on debt markets and
may lead to periods of high volatility and reduced liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest Rate Risk: In general,
the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest
rate risk is generally greater for instruments with longer maturities or durations, or that do not pay
current interest.
|
| Credit Risk |
Credit Risk: The
price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty,
or other entity responsible for payment, or underlying collateral or assets and the terms of the instrument.
The price of a debt instrument can decline in response to changes in, or perceptions of, the financial
condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets,
or changes in, or perceptions of, specific or general market, economic, industry, political, regulatory,
geopolitical, environmental, public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults during economic
downturns or similar periods of economic stress, which in turn could negatively affect the market value
and liquidity of a debt instrument. The credit quality of, and
the ability to pay principal and interest when due by, an issuer of a municipal instrument depends on
the credit quality of the entity supporting the municipal instrument, how essential any services supported
by the municipal instrument are, the sufficiency of any revenues or taxes that support the municipal
instrument, and/or the willingness or ability of the appropriate government entity to approve any appropriations
necessary to support the municipal instrument. In addition, the price of a municipal instrument also
depends on its credit quality and ability to meet the credit support obligations of any insurer or other
entity providing credit support to a municipal instrument. Below
investment grade quality debt instruments (commonly referred to as “high yield securities” or “junk
bonds”) can involve a substantially greater risk of default or can already be in default, and their
values can decline significantly. Below investment grade quality debt instruments are regarded as having
predominantly speculative characteristics. Below investment grade quality debt instruments tend to be
more sensitive to adverse news about the issuer, or the market or economy in general, than higher quality
debt instruments.
|
| Focus Risk |
Focus Risk: The fund’s performance
will be closely tied to the economic, political, environmental, and public health conditions in Mississippi,
and can be more volatile than the performance of a more geographically diversified fund. In addition,
the fund's performance can also be tied to the economic and political conditions of other states and
U.S. territories and possessions in which the fund is invested. These conditions may include constitutional
or statutory limits on an issuer’s ability to raise revenues or increase taxes, anticipated or actual
budget deficits or other financial difficulties, or changes in the credit quality of municipal issuers
in the state, other states, or U.S. territories and possessions.
|
| Non-Diversification Risk |
Non-Diversification
Risk: Because MFS may invest a significant percentage of the fund’s
assets in a single issuer or small number of issuers, the fund’s performance could be closely tied
to the value of that one issuer or issuers, and could be more volatile than the performance of diversified
funds.
|
| Municipal Risk |
Municipal Risk: The price of a municipal
instrument can be volatile and significantly affected by adverse tax changes or court rulings, legislative
or political changes, changes in specific or general market and economic conditions and developments,
and the financial condition of municipal issuers and insurers. Because many municipal instruments are
issued to finance similar projects, conditions in certain industries can significantly affect the fund
and the overall municipal market. Municipal instruments may be more susceptible to downgrades or defaults
during economic downturns or similar periods of economic stress, which in turn could affect the market
values and marketability of many or all municipal obligations of issuers in a state, U.S. territory,
or possession. In addition, because some municipal obligations
may be secured or guaranteed by banks and other institutions, the risk associated with investments in
such municipal securities could increase if the banking or financial sector suffers an economic downturn
and/or if the credit ratings of the institutions issuing the guarantee are downgraded or at risk of being
downgraded by a national rating organization. If such events occur, the value of the security could decrease
or the value could be lost entirely, and it may be difficult or impossible to sell the security at the
time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS Municipal Income Fund
|
Risk Table - Prospectus Summary - MFS Municipal Income Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer,
borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions
of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental,
public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults
during economic downturns or similar periods of economic stress, which in turn could negatively affect
the market value and liquidity of a debt instrument. The credit quality of, and the ability to pay principal and interest when due
by, an issuer of a municipal instrument depends on the credit quality of the entity supporting the municipal
instrument, how essential any services supported by the municipal instrument are, the sufficiency of
any revenues or taxes that support the municipal instrument, and/or the willingness or ability of the
appropriate government entity to approve any appropriations necessary to support the municipal instrument.
In addition, the price of a municipal instrument also depends on its credit quality and ability to meet
the credit support obligations of any insurer or other entity providing credit support to a municipal
instrument. Below investment grade quality debt instruments
(commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially
greater risk of default or can already be in default, and their values can decline significantly. Below
investment grade quality debt instruments are regarded as having predominantly speculative characteristics.
Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer,
or the market or economy in general, than higher quality debt instruments.
|
| Municipal Risk |
Municipal
Risk: The price of a municipal instrument can be volatile and significantly affected
by adverse tax changes or court rulings, legislative or political changes, changes in specific or general
market and economic conditions and developments, and the financial condition of municipal issuers and
insurers. Because many municipal instruments are issued to finance similar projects, conditions in certain
industries can significantly affect the fund and the overall municipal market. Municipal instruments
may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic
stress, which in turn could affect the market values and marketability of many or all municipal obligations
of issuers in a state, U.S. territory, or possession. In addition,
because some municipal obligations may be secured or guaranteed by banks and other institutions, the
risk associated with investments in such municipal securities could increase if the banking or financial
sector suffers an economic downturn and/or if the credit ratings of the institutions issuing the guarantee
are downgraded or at risk of being downgraded by a national rating organization. If such events occur,
the value of the security could decrease or the value could be lost entirely, and it may be difficult
or impossible to sell the security at the time and the price that normally prevails in the market.
|
| Focus Risk |
Focus
Risk: The fund’s performance will be closely tied to the issuer, market, economic,
industry, political, regulatory, geopolitical, environmental, public health, and other conditions in
the states, territories, and possessions of the United States in which the fund's assets are invested.
If MFS invests a significant percentage of the fund's assets in a single state, territory, or possession,
or a small number of states, territories, or possessions, these conditions will have a significant impact
on the fund's performance and the fund's performance may be more volatile than the performance of more
geographically-diversified funds.
|
| Prepayment/Extension Risk |
Prepayment/Extension Risk:
Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS Municipal Income Fund
|
Risk Table - Prospectus Summary - MFS Municipal Income Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer,
borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions
of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental,
public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults
during economic downturns or similar periods of economic stress, which in turn could negatively affect
the market value and liquidity of a debt instrument. The credit
quality of, and the ability to pay principal and interest when due by, an issuer of a municipal instrument
depends on the credit quality of the entity supporting the municipal instrument, how essential any services
supported by the municipal instrument are, the sufficiency of any revenues or taxes that support the
municipal instrument, and/or the willingness or ability of the appropriate government entity to approve
any appropriations necessary to support the municipal instrument. In addition, the price of a municipal
instrument also depends on its credit quality and ability to meet the credit support obligations of any insurer or other entity providing credit
support to a municipal instrument. Below investment
grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”)
can involve a substantially greater risk of default or can already be in default, and their values can
decline significantly. Below investment grade quality debt instruments are regarded as having predominantly
speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive
to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments.
|
| Municipal Risk |
Municipal
Risk: The price of a municipal instrument can be volatile and significantly affected
by adverse tax changes or court rulings, legislative or political changes, changes in specific or general
market and economic conditions and developments, and the financial condition of municipal issuers and
insurers. Because many municipal instruments are issued to finance similar projects, conditions in certain
industries can significantly affect the fund and the overall municipal market. Municipal instruments
may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic
stress, which in turn could affect the market values and marketability of many or all municipal obligations
of issuers in a state, U.S. territory, or possession. In addition,
because some municipal obligations may be secured or guaranteed by banks and other institutions, the
risk associated with investments in such municipal securities could increase if the banking or financial
sector suffers an economic downturn and/or if the credit ratings of the institutions issuing the guarantee
are downgraded or at risk of being downgraded by a national rating organization. If such events occur,
the value of the security could decrease or the value could be lost entirely, and it may be difficult
or impossible to sell the security at the time and the price that normally prevails in the market.
|
| Focus Risk |
Focus
Risk: The fund’s performance will be closely tied to the issuer, market, economic,
industry, political, regulatory, geopolitical, environmental, public health, and other conditions in
the states, territories, and possessions of the United States in which the fund's assets are invested.
If MFS invests a significant percentage of the fund's assets in a single state, territory, or possession,
or a small number of states, territories, or possessions, these conditions will have a significant impact
on the fund's performance and the fund's performance may be more volatile than the performance of more
geographically-diversified funds.
|
| Prepayment/Extension Risk |
Prepayment/Extension Risk:
Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS Municipal Intermediate Fund
|
Risk Table - Prospectus Summary - MFS Municipal Intermediate Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer,
borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions
of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental,
public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults
during economic downturns or similar periods of economic stress, which in turn could negatively affect
the market value and liquidity of a debt instrument. The credit
quality of, and the ability to pay principal and interest when due by, an issuer of a municipal instrument
depends on the credit quality of the entity supporting the municipal instrument, how essential any services supported by the municipal instrument are, the sufficiency
of any revenues or taxes that support the municipal instrument, and/or the willingness or ability of
the appropriate government entity to approve any appropriations necessary to support the municipal instrument.
In addition, the price of a municipal instrument also depends on its credit quality and ability to meet
the credit support obligations of any insurer or other entity providing credit support to a municipal
instrument. Below investment grade quality debt instruments
(commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially
greater risk of default or can already be in default, and their values can decline significantly. Below
investment grade quality debt instruments are regarded as having predominantly speculative characteristics.
Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer,
or the market or economy in general, than higher quality debt instruments.
|
| Municipal Risk |
Municipal
Risk: The price of a municipal instrument can be volatile and significantly affected
by adverse tax changes or court rulings, legislative or political changes, changes in specific or general
market and economic conditions and developments, and the financial condition of municipal issuers and
insurers. Because many municipal instruments are issued to finance similar projects, conditions in certain
industries can significantly affect the fund and the overall municipal market. Municipal instruments
may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic
stress, which in turn could affect the market values and marketability of many or all municipal obligations
of issuers in a state, U.S. territory, or possession. In addition,
because some municipal obligations may be secured or guaranteed by banks and other institutions, the
risk associated with investments in such municipal securities could increase if the banking or financial
sector suffers an economic downturn and/or if the credit ratings of the institutions issuing the guarantee
are downgraded or at risk of being downgraded by a national rating organization. If such events occur,
the value of the security could decrease or the value could be lost entirely, and it may be difficult
or impossible to sell the security at the time and the price that normally prevails in the market.
|
| Focus Risk |
Focus
Risk: The fund’s performance will be closely tied to the issuer, market, economic,
industry, political, regulatory, geopolitical, environmental, public health, and other conditions in
the states, territories, and possessions of the United States in which the fund's assets are invested.
If MFS invests a significant percentage of the fund's assets in a single state, territory, or possession,
or a small number of states, territories, or possessions, these conditions will have a significant impact
on the fund's performance and the fund's performance may be more volatile than the performance of more
geographically-diversified funds.
|
| Prepayment/Extension Risk |
Prepayment/Extension Risk:
Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS New York Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS New York Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying
collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry,
political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments
may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic
stress, which in turn could negatively affect the market value and liquidity of a debt instrument. The credit quality of, and the ability to pay principal and interest when due
by, an issuer of a municipal instrument depends on the credit quality of the entity supporting the municipal
instrument, how essential any services supported by the municipal instrument are, the sufficiency of
any revenues or taxes that support the municipal instrument, and/or the willingness or ability of the
appropriate government entity to approve any appropriations necessary to support the municipal instrument.
In addition, the price of a municipal instrument also depends on its credit quality and ability to meet
the credit support obligations of any insurer or other entity providing credit support to a municipal
instrument. Below investment grade quality debt instruments
(commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially
greater risk of default or can already be in default, and their values can decline significantly. Below
investment grade quality debt instruments are regarded as having predominantly speculative characteristics.
Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer,
or the market or economy in general, than higher quality debt instruments.
|
| Focus Risk |
Focus Risk:
The fund’s performance will be closely tied to the economic, political, environmental,
and public health conditions in New York, and can be more volatile than the performance of a more geographically
diversified fund. In addition, the fund's performance can also be tied to the economic and political
conditions of other states and U.S. territories and possessions in which the fund is invested. These
conditions may include constitutional or statutory limits on an issuer’s ability to raise revenues
or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes
in the credit quality of municipal issuers in the state, other states, or U.S. territories and possessions. If MFS invests a significant percentage of the fund's assets in a single issuer
or small number of issuers, the fund’s performance could be more volatile than the performance of more
diversified funds.
|
| Municipal Risk |
Municipal Risk: The price
of a municipal instrument can be volatile and significantly affected by adverse tax changes or court
rulings, legislative or political changes, changes in specific or general market and economic conditions
and developments, and the financial condition of municipal issuers and insurers. Because many municipal
instruments are issued to finance similar projects, conditions in certain industries can significantly
affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades
or defaults during economic downturns or similar periods of economic stress, which in turn could affect
the market values and marketability of many or all municipal obligations of issuers in a state, U.S.
territory, or possession. In addition, because some
municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated
with investments in such municipal securities could increase if the banking or financial sector suffers
an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded
or at risk of being downgraded by a national rating organization. If such events occur, the value of
the security could decrease or the value could be lost entirely, and it may be difficult or impossible
to sell the security at the time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS North Carolina Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS North Carolina Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying
collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry,
political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments
may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic
stress, which in turn could negatively affect the market value and liquidity of a debt instrument. The credit quality of, and the ability to pay principal and interest when due
by, an issuer of a municipal instrument depends on the credit quality of the entity supporting the municipal
instrument, how essential any services supported by the municipal instrument are, the sufficiency of
any revenues or taxes that support the municipal instrument, and/or the willingness or ability of the
appropriate government entity to approve any appropriations necessary to support the municipal instrument.
In addition, the price of a municipal instrument also depends on its credit quality and ability to meet
the credit support obligations of any insurer or other entity providing credit support to a municipal
instrument. Below investment grade quality debt instruments
(commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially
greater risk of default or can already be in default, and their values can decline significantly. Below
investment grade quality debt instruments are regarded as having predominantly speculative characteristics.
Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer,
or the market or economy in general, than higher quality debt instruments.
|
| Focus Risk |
Focus Risk:
The fund’s performance will be closely tied to the economic, political, environmental,
and public health conditions in North Carolina, and can be more volatile than the performance of a more
geographically diversified fund. In addition, the fund's performance can also be tied to the economic
and political conditions of other states and U.S. territories and possessions in which the fund is invested.
These conditions may include constitutional or statutory limits on an issuer’s ability to raise revenues
or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes
in the credit quality of municipal issuers in the state, other states, or U.S. territories and possessions. If MFS invests a significant percentage of the fund's assets in a single issuer
or small number of issuers, the fund’s performance could be more volatile than the performance of more
diversified funds.
|
| Municipal Risk |
Municipal Risk: The price
of a municipal instrument can be volatile and significantly affected by adverse tax changes or court
rulings, legislative or political changes, changes in specific or general market and economic conditions
and developments, and the financial condition of municipal issuers and insurers. Because many municipal
instruments are issued to finance similar projects, conditions in certain industries can significantly
affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades
or defaults during economic downturns or similar periods of economic stress, which in turn could affect
the market values and marketability of many or all municipal obligations of issuers in a state, U.S.
territory, or possession. In addition, because some
municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated
with investments in such municipal securities could increase if the banking or financial sector suffers
an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded
or at risk of being downgraded by a national rating organization. If such events occur, the value of
the security could decrease or the value could be lost entirely, and it may be difficult or impossible
to sell the security at the time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS Pennsylvania Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS Pennsylvania Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer,
borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions
of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental,
public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults
during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of
a debt instrument. The credit quality of, and the ability to pay
principal and interest when due by, an issuer of a municipal instrument depends on the credit quality
of the entity supporting the municipal instrument, how essential any services supported by the municipal
instrument are, the sufficiency of any revenues or taxes that support the municipal instrument, and/or
the willingness or ability of the appropriate government entity to approve any appropriations necessary
to support the municipal instrument. In addition, the price of a municipal instrument also depends on
its credit quality and ability to meet the credit support obligations of any insurer or other entity
providing credit support to a municipal instrument. Below investment
grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”)
can involve a substantially greater risk of default or can already be in default, and their values can
decline significantly. Below investment grade quality debt instruments are regarded as having predominantly
speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive
to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments.
|
| Focus Risk |
Focus
Risk: The fund’s performance will be closely tied to the economic, political, environmental,
and public health conditions in Pennsylvania, and can be more volatile than the performance of a more
geographically diversified fund. In addition, the fund's performance can also be tied to the economic
and political conditions of other states and U.S. territories and possessions in which the fund is invested.
These conditions may include constitutional or statutory limits on an issuer’s ability to raise revenues
or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes
in the credit quality of municipal issuers in the state, other states, or U.S. territories and possessions. If MFS invests a significant percentage of the fund's assets in a single issuer
or small number of issuers, the fund’s performance could be more volatile than the performance of more
diversified funds.
|
| Municipal Risk |
Municipal Risk: The price
of a municipal instrument can be volatile and significantly affected by adverse tax changes or court
rulings, legislative or political changes, changes in specific or general market and economic conditions
and developments, and the financial condition of municipal issuers and insurers. Because many municipal
instruments are issued to finance similar projects, conditions in certain industries can significantly
affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades
or defaults during economic downturns or similar periods of economic stress, which in turn could affect
the market values and marketability of many or all municipal obligations of issuers in a state, U.S.
territory, or possession. In addition, because some
municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated
with investments in such municipal securities could increase if the banking or financial sector suffers
an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded
or at risk of being downgraded by a national rating organization. If such events occur, the value of
the security could decrease or the value could be lost entirely, and it may be difficult or impossible
to sell the security at the time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS South Carolina Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS South Carolina Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer,
borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions
of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental,
public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults
during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of
a debt instrument. The credit quality of, and the ability to pay
principal and interest when due by, an issuer of a municipal instrument depends on the credit quality
of the entity supporting the municipal instrument, how essential any services supported by the municipal
instrument are, the sufficiency of any revenues or taxes that support the municipal instrument, and/or
the willingness or ability of the appropriate government entity to approve any appropriations necessary
to support the municipal instrument. In addition, the price of a municipal instrument also depends on
its credit quality and ability to meet the credit support obligations of any insurer or other entity
providing credit support to a municipal instrument. Below investment
grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”)
can involve a substantially greater risk of default or can already be in default, and their values can
decline significantly. Below investment grade quality debt instruments are regarded as having predominantly
speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive
to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments.
|
| Focus Risk |
Focus
Risk: The fund’s performance will be closely tied to the economic, political, environmental,
and public health conditions in South Carolina, and can be more volatile than the performance of a more
geographically diversified fund. In addition, the fund's performance can also be tied to the economic
and political conditions of other states and U.S. territories and possessions in which the fund is invested.
These conditions may include constitutional or statutory limits on an issuer’s ability to raise revenues
or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes
in the credit quality of municipal issuers in the state, other states, or U.S. territories and possessions. If MFS invests a significant percentage of the fund's assets in a single issuer
or small number of issuers, the fund’s performance could be more volatile than the performance of more
diversified funds.
|
| Municipal Risk |
Municipal Risk: The price
of a municipal instrument can be volatile and significantly affected by adverse tax changes or court
rulings, legislative or political changes, changes in specific or general market and economic conditions
and developments, and the financial condition of municipal issuers and insurers. Because many municipal
instruments are issued to finance similar projects, conditions in certain industries can significantly
affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades
or defaults during economic downturns or similar periods of economic stress, which in turn could affect
the market values and marketability of many or all municipal obligations of issuers in a state, U.S.
territory, or possession. In addition, because some
municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated
with investments in such municipal securities could increase if the banking or financial sector suffers
an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded
or at risk of being downgraded by a national rating organization. If such events occur, the value of
the security could decrease or the value could be lost entirely, and it may be difficult or impossible
to sell the security at the time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS Virginia Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS Virginia Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal Risks As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency. The principal risks of investing
in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the
fund may not achieve its objective and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment
in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation
or any other governmental agency.
|
| Investment Selection Risk |
Investment Selection Risk: MFS'
investment analysis and its selection of investments may not produce the intended results and/or can
lead to an investment focus that results in the fund underperforming other funds with similar investment
strategies and/or underperforming the markets in which the fund invests. In addition, to the extent
MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market Risk: Debt markets can be volatile
and can decline significantly in response to changes in, or investor perceptions of, issuer, market,
economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions.
These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument,
issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can
have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced
liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest
Rate Risk: In general, the price of
a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk
is generally greater for instruments with longer maturities or durations, or that do not pay current
interest.
|
| Credit Risk |
Credit Risk: The price of a debt instrument
depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible
for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt
instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying
collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry,
political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments
may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic
stress, which in turn could negatively affect the market value and liquidity of a debt instrument. The credit quality of, and the ability to pay principal and interest when due
by, an issuer of a municipal instrument depends on the credit quality of the entity supporting the municipal
instrument, how essential any services supported by the municipal instrument are, the sufficiency of
any revenues or taxes that support the municipal instrument, and/or the willingness or ability of the
appropriate government entity to approve any appropriations necessary to support the municipal instrument.
In addition, the price of a municipal instrument also depends on its credit quality and ability to meet
the credit support obligations of any insurer or other entity providing credit support to a municipal
instrument. Below investment grade quality debt instruments
(commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially
greater risk of default or can already be in default, and their values can decline significantly. Below
investment grade quality debt instruments are regarded as having predominantly speculative characteristics.
Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer,
or the market or economy in general, than higher quality debt instruments.
|
| Focus Risk |
Focus Risk:
The fund’s performance will be closely tied to the economic, political, environmental,
and public health conditions in Virginia, and can be more volatile than the performance of a more geographically
diversified fund. In addition, the fund's performance can also be tied to the economic and political
conditions of other states and U.S. territories and possessions in which the fund is invested. These
conditions may include constitutional or statutory limits on an issuer’s ability to raise revenues
or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes
in the credit quality of municipal issuers in the state, other states, or U.S. territories and possessions. If MFS invests a significant percentage of the fund's assets in a single issuer
or small number of issuers, the fund’s performance could be more volatile than the performance of more
diversified funds.
|
| Municipal Risk |
Municipal Risk: The price
of a municipal instrument can be volatile and significantly affected by adverse tax changes or court
rulings, legislative or political changes, changes in specific or general market and economic conditions
and developments, and the financial condition of municipal issuers and insurers. Because many municipal
instruments are issued to finance similar projects, conditions in certain industries can significantly
affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades
or defaults during economic downturns or similar periods of economic stress, which in turn could affect
the market values and marketability of many or all municipal obligations of issuers in a state, U.S.
territory, or possession. In addition, because some
municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated
with investments in such municipal securities could increase if the banking or financial sector suffers
an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded
or at risk of being downgraded by a national rating organization. If such events occur, the value of
the security could decrease or the value could be lost entirely, and it may be difficult or impossible
to sell the security at the time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|
| Prospectus Summary | MFS West Virginia Municipal Bond Fund
|
Risk Table - Prospectus Summary - MFS West Virginia Municipal Bond Fund
|
Risk [Text Block] |
| Principal Risks |
Principal
Risks As with any mutual fund, the fund may not achieve its objective
and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit
and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental
agency. The principal risks of investing in the fund are:
|
| Risk Lose Money [Member] |
As with any mutual fund, the fund may not achieve its objective
and/or you could lose money on your investment in the fund.
|
| Risk Not Insured [Member] |
An investment in the fund is not a bank deposit
and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental
agency.
|
| Investment Selection Risk |
Investment
Selection Risk: MFS' investment analysis and its selection of investments
may not produce the intended results and/or can lead to an investment focus that results in the fund
underperforming other funds with similar investment strategies and/or underperforming the markets in
which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the
fund, such tools may not produce the intended results.
|
| Debt Market Risk |
Debt Market
Risk: Debt markets can be volatile and can decline significantly in response to changes
in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical,
environmental, public health, and other conditions. These conditions can affect a single instrument,
issuer, or borrower, a particular type of instrument, issuer, or borrower, a segment of the debt markets
or the debt markets generally. Certain events can have a dramatic adverse effect on debt markets and
may lead to periods of high volatility and reduced liquidity in a debt market or segment of a debt market.
|
| Interest Rate Risk |
Interest Rate Risk: In general,
the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest
rate risk is generally greater for instruments with longer maturities or durations, or that do not pay
current interest.
|
| Credit Risk |
Credit Risk: The
price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty,
or other entity responsible for payment, or underlying collateral or assets and the terms of the instrument.
The price of a debt instrument can decline in response to changes in, or perceptions of, the financial
condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets,
or changes in, or perceptions of, specific or general market, economic, industry, political, regulatory,
geopolitical, environmental, public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults during economic
downturns or similar periods of economic stress, which in turn could negatively affect the market value
and liquidity of a debt instrument. The credit quality of, and
the ability to pay principal and interest when due by, an issuer of a municipal instrument depends on
the credit quality of the entity supporting the municipal instrument, how essential any services supported
by the municipal instrument are, the sufficiency of any revenues or taxes that support the municipal
instrument, and/or the willingness or ability of the appropriate government entity to approve any appropriations
necessary to support the municipal instrument. In addition, the price of a municipal instrument also
depends on its credit quality and ability to meet the credit support obligations of any insurer or other
entity providing credit support to a municipal instrument. Below
investment grade quality debt instruments (commonly referred to as “high yield securities” or “junk
bonds”) can involve a substantially greater risk of default or can already be in default, and their
values can decline significantly. Below investment grade quality debt instruments are regarded as having
predominantly speculative characteristics. Below investment grade quality debt instruments tend to be
more sensitive to adverse news about the issuer, or the market or economy in general, than higher quality
debt instruments.
|
| Focus Risk |
Focus Risk: The fund’s performance
will be closely tied to the economic, political, environmental, and public health conditions in West
Virginia, and can be more volatile than the performance of a more geographically diversified fund. In
addition, the fund's performance can also be tied to the economic and political conditions of other states
and U.S. territories and possessions in which the fund is invested. These conditions may include constitutional
or statutory limits on an issuer’s ability to raise revenues or increase taxes, anticipated or actual
budget deficits or other financial difficulties, or changes in the credit quality of municipal issuers
in the state, other states, or U.S. territories and possessions.
|
| Non-Diversification Risk |
Non-Diversification
Risk: Because MFS may invest a significant percentage of the fund’s
assets in a single issuer or small number of issuers, the fund’s performance could be closely tied
to the value of that one issuer or issuers, and could be more volatile than the performance of diversified
funds.
|
| Municipal Risk |
Municipal Risk: The price of a municipal
instrument can be volatile and significantly affected by adverse tax changes or court rulings, legislative
or political changes, changes in specific or general market and economic conditions and developments,
and the financial condition of municipal issuers and insurers. Because many municipal instruments are
issued to finance similar projects, conditions in certain industries can significantly affect the fund
and the overall municipal market. Municipal instruments may be more susceptible to downgrades or defaults
during economic downturns or similar periods of economic stress, which in turn could affect the market
values and marketability of many or all municipal obligations of issuers in a state, U.S. territory,
or possession. In addition, because some municipal obligations
may be secured or guaranteed by banks and other institutions, the risk associated with investments in
such municipal securities could increase if the banking or financial sector suffers an economic downturn
and/or if the credit ratings of the institutions issuing the guarantee are downgraded or at risk of being
downgraded by a national rating organization. If such events occur, the value of the security could decrease
or the value could be lost entirely, and it may be difficult or impossible to sell the security at the
time and the price that normally prevails in the market.
|
| Prepayment/Extension Risk |
Prepayment/Extension
Risk: Instruments subject to prepayment and/or extension can reduce
the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential
for loss if the maturity of the instrument is extended.
|
| Derivatives Risk |
Derivatives
Risk: Derivatives can be highly volatile and involve risks in addition
to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives
can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.
|
| Leveraging Risk |
Leveraging
Risk: Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
|
| Counterparty and Third Party Risk |
Counterparty
and Third Party Risk: Transactions involving a
counterparty or third party other than the issuer of the instrument are subject to the credit risk of
the counterparty or third party, and to the counterparty’s or third party’s ability or willingness
to perform in accordance with the terms of the transaction.
|
| Liquidity Risk |
Liquidity
Risk: It may be difficult to value, and it may not be possible to
sell, certain investments, types of investments, and/or investments in certain segments of the market,
and the fund may have to sell certain of these investments at prices or times that are not advantageous
in order to meet redemptions or other cash needs.
|
| Large Shareholder Risk |
Large Shareholder
Risk: From time to time, shareholders of the fund (which may include institutional investors,
financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund
shares. These transactions may cause the fund to sell securities or invest additional cash, as the case
may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction
and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of
portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance
to the extent that it takes time to invest new cash and the fund maintains a larger cash position than
it ordinarily would.
|
|