This semi-annual shareholder report contains important information about Loomis Sayles High Income Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

You can find additional information (including tax information) about the Fund at im.natixis.com/funddocuments. You can also request the information by contacting us at (800) 225-5478 or by contacting your financial intermediary directly.

Additional Information Phone Number

(800) 225-5478

Additional Information Website

<span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 18px; margin: 0px; overflow: visible; text-align: left; text-align-last: auto; white-space-collapse: preserve-breaks;">im.natixis.com/funddocuments</span>

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class A	$48	0.95%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 48

Expense Ratio, Percent

0.95%

AssetsNet

$ 89,901,598

Holdings Count | Holding

349

Advisory Fees Paid, Amount

$ 92,233

InvestmentCompanyPortfolioTurnover

50.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$89,901,598
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)349
Portfolio Turnover Rate50%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$92,233

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	37.1%
Short-Term Investments	5.1%
Healthcare	3.3%
Retailers	3.4%
Lodging	3.5%
Automotive	3.5%
Metals & Mining	3.6%
Media Entertainment	4.0%
Independent Energy	4.0%
Property & Casualty Insurance	4.9%
Midstream	6.3%
Cable Satellite	9.1%
Technology	12.2%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	4.0
Not rated^{Footnote Reference^}	4.6
CC	0.4
CCC	4.2
B	28.2
BB	57.0
BBB	1.7

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000018233

Shareholder Report [Line Items]

Fund Name

Loomis Sayles High Income Fund

Class Name

Class C

Trading Symbol

NEHCX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles High Income Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class C	$85	1.70%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 85

Expense Ratio, Percent

1.70%

AssetsNet

$ 89,901,598

Holdings Count | Holding

349

Advisory Fees Paid, Amount

$ 92,233

InvestmentCompanyPortfolioTurnover

50.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$89,901,598
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)349
Portfolio Turnover Rate50%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$92,233

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	37.1%
Short-Term Investments	5.1%
Healthcare	3.3%
Retailers	3.4%
Lodging	3.5%
Automotive	3.5%
Metals & Mining	3.6%
Media Entertainment	4.0%
Independent Energy	4.0%
Property & Casualty Insurance	4.9%
Midstream	6.3%
Cable Satellite	9.1%
Technology	12.2%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	4.0
Not rated^{Footnote Reference^}	4.6
CC	0.4
CCC	4.2
B	28.2
BB	57.0
BBB	1.7

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000175112

Shareholder Report [Line Items]

Fund Name

Loomis Sayles High Income Fund

Class Name

Class N

Trading Symbol

LSHNX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles High Income Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class N	$33	0.65%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 33

Expense Ratio, Percent

0.65%

AssetsNet

$ 89,901,598

Holdings Count | Holding

349

Advisory Fees Paid, Amount

$ 92,233

InvestmentCompanyPortfolioTurnover

50.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$89,901,598
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)349
Portfolio Turnover Rate50%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$92,233

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	37.1%
Short-Term Investments	5.1%
Healthcare	3.3%
Retailers	3.4%
Lodging	3.5%
Automotive	3.5%
Metals & Mining	3.6%
Media Entertainment	4.0%
Independent Energy	4.0%
Property & Casualty Insurance	4.9%
Midstream	6.3%
Cable Satellite	9.1%
Technology	12.2%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	4.0
Not rated^{Footnote Reference^}	4.6
CC	0.4
CCC	4.2
B	28.2
BB	57.0
BBB	1.7

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000069253

Shareholder Report [Line Items]

Fund Name

Loomis Sayles High Income Fund

Class Name

Class Y

Trading Symbol

NEHYX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles High Income Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class Y	$35	0.70%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 35

Expense Ratio, Percent

0.70%

AssetsNet

$ 89,901,598

Holdings Count | Holding

349

Advisory Fees Paid, Amount

$ 92,233

InvestmentCompanyPortfolioTurnover

50.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$89,901,598
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)349
Portfolio Turnover Rate50%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$92,233

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	37.1%
Short-Term Investments	5.1%
Healthcare	3.3%
Retailers	3.4%
Lodging	3.5%
Automotive	3.5%
Metals & Mining	3.6%
Media Entertainment	4.0%
Independent Energy	4.0%
Property & Casualty Insurance	4.9%
Midstream	6.3%
Cable Satellite	9.1%
Technology	12.2%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	4.0
Not rated^{Footnote Reference^}	4.6
CC	0.4
CCC	4.2
B	28.2
BB	57.0
BBB	1.7

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000223747

Shareholder Report [Line Items]

Fund Name

Loomis Sayles International Growth Fund

Class Name

Class A

Trading Symbol

LIGGX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles International Growth Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class A	$57	1.21%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 57

Expense Ratio, Percent

1.21%

AssetsNet

$ 24,155,717

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 0

InvestmentCompanyPortfolioTurnover

10.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$24,155,717
# of Portfolio Holdings (including overnight repurchase agreements)35
Portfolio Turnover Rate10%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$0

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	13.9%
Short-Term Investments	3.7%
Machinery	3.0%
IT Services	4.6%
Hotels, Restaurants & Leisure	6.1%
Interactive Media & Services	6.2%
Financial Services	6.5%
Software	6.9%
Broadline Retail	7.9%
Automobiles	8.4%
Beverages	9.1%
Semiconductors & Semiconductor Equipment	10.9%
Pharmaceuticals	12.8%

Footnote	Description
Footnote^*	Net of other assets less liabilities

Country Weightings

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	6.6%
Germany	3.3%
Japan	3.6%
Australia	3.6%
Denmark	4.2%
United Kingdom	4.2%
Canada	4.6%
France	5.1%
Netherlands	7.6%
Brazil	9.4%
China	15.5%
United States	32.3%

Footnote	Description
Footnote^*	Net of other assets less liabilities

Largest Holdings [Text Block]

Top Ten Holdings

Table Summary
ARM Holdings PLC, ADR	7.9%
Tesla, Inc.	7.2%
MercadoLibre, Inc.	6.1%
Adyen NV	4.6%
Shopify, Inc., Class A	4.6%
Tencent Holdings Ltd.	4.5%
Roche Holding AG	4.5%
Novo Nordisk AS, Class B	4.2%
Novartis AG	4.1%
Trip.com Group Ltd., ADR	3.8%

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000223748

Shareholder Report [Line Items]

Fund Name

Loomis Sayles International Growth Fund

Class Name

Class C

Trading Symbol

LIGCX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles International Growth Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class C	$93	1.97%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 93

Expense Ratio, Percent

1.97%

AssetsNet

$ 24,155,717

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 0

InvestmentCompanyPortfolioTurnover

10.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$24,155,717
# of Portfolio Holdings (including overnight repurchase agreements)35
Portfolio Turnover Rate10%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$0

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	13.9%
Short-Term Investments	3.7%
Machinery	3.0%
IT Services	4.6%
Hotels, Restaurants & Leisure	6.1%
Interactive Media & Services	6.2%
Financial Services	6.5%
Software	6.9%
Broadline Retail	7.9%
Automobiles	8.4%
Beverages	9.1%
Semiconductors & Semiconductor Equipment	10.9%
Pharmaceuticals	12.8%

Footnote	Description
Footnote^*	Net of other assets less liabilities

Country Weightings

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	6.6%
Germany	3.3%
Japan	3.6%
Australia	3.6%
Denmark	4.2%
United Kingdom	4.2%
Canada	4.6%
France	5.1%
Netherlands	7.6%
Brazil	9.4%
China	15.5%
United States	32.3%

Footnote	Description
Footnote^*	Net of other assets less liabilities

Largest Holdings [Text Block]

Top Ten Holdings

Table Summary
ARM Holdings PLC, ADR	7.9%
Tesla, Inc.	7.2%
MercadoLibre, Inc.	6.1%
Adyen NV	4.6%
Shopify, Inc., Class A	4.6%
Tencent Holdings Ltd.	4.5%
Roche Holding AG	4.5%
Novo Nordisk AS, Class B	4.2%
Novartis AG	4.1%
Trip.com Group Ltd., ADR	3.8%

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000223749

Shareholder Report [Line Items]

Fund Name

Loomis Sayles International Growth Fund

Class Name

Class N

Trading Symbol

LIGNX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles International Growth Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class N	$43	0.91%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 43

Expense Ratio, Percent

0.91%

AssetsNet

$ 24,155,717

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 0

InvestmentCompanyPortfolioTurnover

10.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$24,155,717
# of Portfolio Holdings (including overnight repurchase agreements)35
Portfolio Turnover Rate10%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$0

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	13.9%
Short-Term Investments	3.7%
Machinery	3.0%
IT Services	4.6%
Hotels, Restaurants & Leisure	6.1%
Interactive Media & Services	6.2%
Financial Services	6.5%
Software	6.9%
Broadline Retail	7.9%
Automobiles	8.4%
Beverages	9.1%
Semiconductors & Semiconductor Equipment	10.9%
Pharmaceuticals	12.8%

Footnote	Description
Footnote^*	Net of other assets less liabilities

Country Weightings

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	6.6%
Germany	3.3%
Japan	3.6%
Australia	3.6%
Denmark	4.2%
United Kingdom	4.2%
Canada	4.6%
France	5.1%
Netherlands	7.6%
Brazil	9.4%
China	15.5%
United States	32.3%

Footnote	Description
Footnote^*	Net of other assets less liabilities

Largest Holdings [Text Block]

Top Ten Holdings

Table Summary
ARM Holdings PLC, ADR	7.9%
Tesla, Inc.	7.2%
MercadoLibre, Inc.	6.1%
Adyen NV	4.6%
Shopify, Inc., Class A	4.6%
Tencent Holdings Ltd.	4.5%
Roche Holding AG	4.5%
Novo Nordisk AS, Class B	4.2%
Novartis AG	4.1%
Trip.com Group Ltd., ADR	3.8%

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000223746

Shareholder Report [Line Items]

Fund Name

Loomis Sayles International Growth Fund

Class Name

Class Y

Trading Symbol

LIGYX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles International Growth Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class Y	$46	0.96%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 46

Expense Ratio, Percent

0.96%

AssetsNet

$ 24,155,717

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 0

InvestmentCompanyPortfolioTurnover

10.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$24,155,717
# of Portfolio Holdings (including overnight repurchase agreements)35
Portfolio Turnover Rate10%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$0

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	13.9%
Short-Term Investments	3.7%
Machinery	3.0%
IT Services	4.6%
Hotels, Restaurants & Leisure	6.1%
Interactive Media & Services	6.2%
Financial Services	6.5%
Software	6.9%
Broadline Retail	7.9%
Automobiles	8.4%
Beverages	9.1%
Semiconductors & Semiconductor Equipment	10.9%
Pharmaceuticals	12.8%

Footnote	Description
Footnote^*	Net of other assets less liabilities

Country Weightings

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	6.6%
Germany	3.3%
Japan	3.6%
Australia	3.6%
Denmark	4.2%
United Kingdom	4.2%
Canada	4.6%
France	5.1%
Netherlands	7.6%
Brazil	9.4%
China	15.5%
United States	32.3%

Footnote	Description
Footnote^*	Net of other assets less liabilities

Largest Holdings [Text Block]

Top Ten Holdings

Table Summary
ARM Holdings PLC, ADR	7.9%
Tesla, Inc.	7.2%
MercadoLibre, Inc.	6.1%
Adyen NV	4.6%
Shopify, Inc., Class A	4.6%
Tencent Holdings Ltd.	4.5%
Roche Holding AG	4.5%
Novo Nordisk AS, Class B	4.2%
Novartis AG	4.1%
Trip.com Group Ltd., ADR	3.8%

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000018234

Shareholder Report [Line Items]

Fund Name

Loomis Sayles Investment Grade Bond Fund

Class Name

Class A

Trading Symbol

LIGRX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles Investment Grade Bond Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class A	$36	0.73%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 36

Expense Ratio, Percent

0.73%

AssetsNet

$ 17,020,155,906

Holdings Count | Holding

1,086

Advisory Fees Paid, Amount

$ 28,680,919

InvestmentCompanyPortfolioTurnover

27.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$17,020,155,906
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)1,086
Portfolio Turnover Rate27%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$28,680,919

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	41.7%
Short-Term Investments	3.4%
Finance Companies	3.0%
Midstream	4.0%
ABS Car Loan	4.4%
Collateralized Loan Obligations	5.2%
Banking	7.2%
ABS Other	7.9%
Technology	9.6%
Treasuries	13.6%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	2.3
US Treasury	13.8
Not rated^{Footnote Reference^}	21.5
CC	0.1
CCC	0.2
B	1.7
BB	7.2
BBB	41.0
A	8.7
AA	2.0
AAA	3.1

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000018236

Shareholder Report [Line Items]

Fund Name

Loomis Sayles Investment Grade Bond Fund

Class Name

Class C

Trading Symbol

LGBCX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles Investment Grade Bond Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class C	$74	1.48%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 74

Expense Ratio, Percent

1.48%

AssetsNet

$ 17,020,155,906

Holdings Count | Holding

1,086

Advisory Fees Paid, Amount

$ 28,680,919

InvestmentCompanyPortfolioTurnover

27.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$17,020,155,906
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)1,086
Portfolio Turnover Rate27%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$28,680,919

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	41.7%
Short-Term Investments	3.4%
Finance Companies	3.0%
Midstream	4.0%
ABS Car Loan	4.4%
Collateralized Loan Obligations	5.2%
Banking	7.2%
ABS Other	7.9%
Technology	9.6%
Treasuries	13.6%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	2.3
US Treasury	13.8
Not rated^{Footnote Reference^}	21.5
CC	0.1
CCC	0.2
B	1.7
BB	7.2
BBB	41.0
A	8.7
AA	2.0
AAA	3.1

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000125485

Shareholder Report [Line Items]

Fund Name

Loomis Sayles Investment Grade Bond Fund

Class Name

Class N

Trading Symbol

LGBNX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles Investment Grade Bond Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class N	$21	0.43%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 21

Expense Ratio, Percent

0.43%

AssetsNet

$ 17,020,155,906

Holdings Count | Holding

1,086

Advisory Fees Paid, Amount

$ 28,680,919

InvestmentCompanyPortfolioTurnover

27.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$17,020,155,906
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)1,086
Portfolio Turnover Rate27%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$28,680,919

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	41.7%
Short-Term Investments	3.4%
Finance Companies	3.0%
Midstream	4.0%
ABS Car Loan	4.4%
Collateralized Loan Obligations	5.2%
Banking	7.2%
ABS Other	7.9%
Technology	9.6%
Treasuries	13.6%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	2.3
US Treasury	13.8
Not rated^{Footnote Reference^}	21.5
CC	0.1
CCC	0.2
B	1.7
BB	7.2
BBB	41.0
A	8.7
AA	2.0
AAA	3.1

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000018238

Shareholder Report [Line Items]

Fund Name

Loomis Sayles Investment Grade Bond Fund

Class Name

Class Y

Trading Symbol

LSIIX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles Investment Grade Bond Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class Y	$24	0.48%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 24

Expense Ratio, Percent

0.48%

AssetsNet

$ 17,020,155,906

Holdings Count | Holding

1,086

Advisory Fees Paid, Amount

$ 28,680,919

InvestmentCompanyPortfolioTurnover

27.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$17,020,155,906
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)1,086
Portfolio Turnover Rate27%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$28,680,919

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	41.7%
Short-Term Investments	3.4%
Finance Companies	3.0%
Midstream	4.0%
ABS Car Loan	4.4%
Collateralized Loan Obligations	5.2%
Banking	7.2%
ABS Other	7.9%
Technology	9.6%
Treasuries	13.6%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	2.3
US Treasury	13.8
Not rated^{Footnote Reference^}	21.5
CC	0.1
CCC	0.2
B	1.7
BB	7.2
BBB	41.0
A	8.7
AA	2.0
AAA	3.1

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000082998

Shareholder Report [Line Items]

Fund Name

Loomis Sayles Investment Grade Bond Fund

Class Name

Admin Class

Trading Symbol

LIGAX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles Investment Grade Bond Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Admin Class	$49	0.98%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 49

Expense Ratio, Percent

0.98%

AssetsNet

$ 17,020,155,906

Holdings Count | Holding

1,086

Advisory Fees Paid, Amount

$ 28,680,919

InvestmentCompanyPortfolioTurnover

27.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$17,020,155,906
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)1,086
Portfolio Turnover Rate27%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$28,680,919

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	41.7%
Short-Term Investments	3.4%
Finance Companies	3.0%
Midstream	4.0%
ABS Car Loan	4.4%
Collateralized Loan Obligations	5.2%
Banking	7.2%
ABS Other	7.9%
Technology	9.6%
Treasuries	13.6%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	2.3
US Treasury	13.8
Not rated^{Footnote Reference^}	21.5
CC	0.1
CCC	0.2
B	1.7
BB	7.2
BBB	41.0
A	8.7
AA	2.0
AAA	3.1

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

There were no material fund changes during the period.

Summary of Change Legend [Text Block]

There were no material fund changes during the period.

C000018251

Shareholder Report [Line Items]

Fund Name

Loomis Sayles Strategic Income Fund

Class Name

Class A

Trading Symbol

NEFZX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles Strategic Income Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Material Fund Change Notice [Text Block]

This report describes changes to the Fund that occurred during the reporting period.

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class A	$46	0.92%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 46

Expense Ratio, Percent

0.92%

Material Change Date

Jun. 30, 2026

AssetsNet

$ 2,689,611,524

Holdings Count | Holding

625

Advisory Fees Paid, Amount

$ 6,694,609

InvestmentCompanyPortfolioTurnover

38.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$2,689,611,524
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)625
Portfolio Turnover Rate38%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$6,694,609

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	42.1%
Short-Term Investments	4.2%
Media Entertainment	3.3%
Banking	3.9%
ABS Other	4.2%
Equity-Linked Notes	6.0%
Sovereigns	6.0%
Cable Satellite	6.5%
Technology	8.1%
Treasuries	15.7%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including open written options, forward foreign currency contracts, and futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	3.4
US Treasury	9.0
Not rated^{Footnote Reference^}	23.4
CC	0.5
CCC	1.7
B	11.5
BB	17.1
BBB	27.0
A	6.1
AA	0.7
AAA	0.7

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

For the six months ended June 30, 2026, the Fund had the following material changes, which were reported in a supplement to the Fund's prospectus. For more information, you may review the Fund's prospectus at im.natixis.com/funddocuments or upon request at (800) 225-5478 or through your financial intermediary.

Fees: Effective July 1, 2026, the advisory fee rate as a percentage of average daily net assets will be 0.59% on the first $2 billion of assets, 0.54% on the next $3 billion in assets and 0.53% thereafter.

Material Fund Change Expenses [Text Block]

Summary of Change Legend [Text Block]

Updated Prospectus Phone Number

(800) 225-5478

Updated Prospectus Web Address

<span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; font-weight: 400; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: left; text-align-last: auto; white-space-collapse: preserve-breaks;">im.natixis.com/funddocuments</span>

C000018253

Shareholder Report [Line Items]

Fund Name

Loomis Sayles Strategic Income Fund

Class Name

Class C

Trading Symbol

NECZX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles Strategic Income Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Material Fund Change Notice [Text Block]

This report describes changes to the Fund that occurred during the reporting period.

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class C	$83	1.67%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 83

Expense Ratio, Percent

1.67%

Material Change Date

Jun. 30, 2026

AssetsNet

$ 2,689,611,524

Holdings Count | Holding

625

Advisory Fees Paid, Amount

$ 6,694,609

InvestmentCompanyPortfolioTurnover

38.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$2,689,611,524
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)625
Portfolio Turnover Rate38%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$6,694,609

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	42.1%
Short-Term Investments	4.2%
Media Entertainment	3.3%
Banking	3.9%
ABS Other	4.2%
Equity-Linked Notes	6.0%
Sovereigns	6.0%
Cable Satellite	6.5%
Technology	8.1%
Treasuries	15.7%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including open written options, forward foreign currency contracts, and futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	3.4
US Treasury	9.0
Not rated^{Footnote Reference^}	23.4
CC	0.5
CCC	1.7
B	11.5
BB	17.1
BBB	27.0
A	6.1
AA	0.7
AAA	0.7

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

Material Fund Change Expenses [Text Block]

Summary of Change Legend [Text Block]

Updated Prospectus Phone Number

(800) 225-5478

Updated Prospectus Web Address

C000125487

Shareholder Report [Line Items]

Fund Name

Loomis Sayles Strategic Income Fund

Class Name

Class N

Trading Symbol

NEZNX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles Strategic Income Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Material Fund Change Notice [Text Block]

This report describes changes to the Fund that occurred during the reporting period.

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class N	$31	0.62%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 31

Expense Ratio, Percent

0.62%

Material Change Date

Jun. 30, 2026

AssetsNet

$ 2,689,611,524

Holdings Count | Holding

625

Advisory Fees Paid, Amount

$ 6,694,609

InvestmentCompanyPortfolioTurnover

38.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$2,689,611,524
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)625
Portfolio Turnover Rate38%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$6,694,609

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	42.1%
Short-Term Investments	4.2%
Media Entertainment	3.3%
Banking	3.9%
ABS Other	4.2%
Equity-Linked Notes	6.0%
Sovereigns	6.0%
Cable Satellite	6.5%
Technology	8.1%
Treasuries	15.7%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including open written options, forward foreign currency contracts, and futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	3.4
US Treasury	9.0
Not rated^{Footnote Reference^}	23.4
CC	0.5
CCC	1.7
B	11.5
BB	17.1
BBB	27.0
A	6.1
AA	0.7
AAA	0.7

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

Material Fund Change Expenses [Text Block]

Summary of Change Legend [Text Block]

Updated Prospectus Phone Number

(800) 225-5478

Updated Prospectus Web Address

C000018254

Shareholder Report [Line Items]

Fund Name

Loomis Sayles Strategic Income Fund

Class Name

Class Y

Trading Symbol

NEZYX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles Strategic Income Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Material Fund Change Notice [Text Block]

This report describes changes to the Fund that occurred during the reporting period.

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Class Y	$33	0.67%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 33

Expense Ratio, Percent

0.67%

Material Change Date

Jun. 30, 2026

AssetsNet

$ 2,689,611,524

Holdings Count | Holding

625

Advisory Fees Paid, Amount

$ 6,694,609

InvestmentCompanyPortfolioTurnover

38.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$2,689,611,524
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)625
Portfolio Turnover Rate38%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$6,694,609

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	42.1%
Short-Term Investments	4.2%
Media Entertainment	3.3%
Banking	3.9%
ABS Other	4.2%
Equity-Linked Notes	6.0%
Sovereigns	6.0%
Cable Satellite	6.5%
Technology	8.1%
Treasuries	15.7%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including open written options, forward foreign currency contracts, and futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	3.4
US Treasury	9.0
Not rated^{Footnote Reference^}	23.4
CC	0.5
CCC	1.7
B	11.5
BB	17.1
BBB	27.0
A	6.1
AA	0.7
AAA	0.7

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

Material Fund Change Expenses [Text Block]

Summary of Change Legend [Text Block]

Updated Prospectus Phone Number

(800) 225-5478

Updated Prospectus Web Address

C000082999

Shareholder Report [Line Items]

Fund Name

Loomis Sayles Strategic Income Fund

Class Name

Admin Class

Trading Symbol

NEZAX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Loomis Sayles Strategic Income Fund for the period of January 1, 2026 to June 30, 2026.

Additional Information [Text Block]

Material Fund Change Notice [Text Block]

This report describes changes to the Fund that occurred during the reporting period.

Additional Information Phone Number

(800) 225-5478

Additional Information Website

Expenses [Text Block]

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Table Summary
Class Name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment^{Footnote Reference†}
Admin Class	$58	1.17%

Footnote	Description
Footnote^†	Annualized for periods less than one year (if applicable).

Expenses Paid, Amount

$ 58

Expense Ratio, Percent

1.17%

Material Change Date

Jun. 30, 2026

AssetsNet

$ 2,689,611,524

Holdings Count | Holding

625

Advisory Fees Paid, Amount

$ 6,694,609

InvestmentCompanyPortfolioTurnover

38.00%

Additional Fund Statistics [Text Block]

Key Fund Statistics

Total Net Assets$2,689,611,524
# of Portfolio Holdings (including overnight repurchase agreements and derivatives)625
Portfolio Turnover Rate38%
Total Advisory Fees Paid (after waiver/reimbursement, if applicable)$6,694,609

Holdings [Text Block]

Industry Summary

Table Summary
Value	Value
Other investments less than 3% of net assets^{Footnote Reference*}	42.1%
Short-Term Investments	4.2%
Media Entertainment	3.3%
Banking	3.9%
ABS Other	4.2%
Equity-Linked Notes	6.0%
Sovereigns	6.0%
Cable Satellite	6.5%
Technology	8.1%
Treasuries	15.7%

Footnote	Description
Footnote^*	Net of other assets less liabilities (including open written options, forward foreign currency contracts, and futures contracts)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Table Summary
Value	Value
Cash & equivalents	3.4
US Treasury	9.0
Not rated^{Footnote Reference^}	23.4
CC	0.5
CCC	1.7
B	11.5
BB	17.1
BBB	27.0
A	6.1
AA	0.7
AAA	0.7

Footnote	Description
Footnote^*	Percentages are calculated based on Net Assets. Totals may not add up to 100% due to other assets and liabilities, such as receivables and payables, not being included in the table.
Footnote^†	Credit ratings are by S&P Global Ratings. A credit rating is an assessment provided by a nationally recognized statistical rating organization (NRSRO) of the creditworthiness of an issuer with respect to debt obligations except for those debt obligations that are only privately rated. Ratings are measured on a scale that generally ranges from AAA (highest) to D (lowest). The credit ratings shown relate to the creditworthiness of the issuers of the underlying securities in the Fund, and not to the Fund or its shares. Credit ratings are subject to change.
Footnote^{^}	Not Rated category represents only those securities not rated by S&P Global Ratings. Such securities may be rated by other NRSROs not shown here.

Credit Quality Explanation [Text Block]

Material Fund Change [Text Block]

Material Fund Changes

Material Fund Change Expenses [Text Block]

Summary of Change Legend [Text Block]

Updated Prospectus Phone Number

(800) 225-5478

Updated Prospectus Web Address

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Credit QualityFootnote Reference*Footnote Reference†

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Credit QualityFootnote Reference*Footnote Reference†

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Credit QualityFootnote Reference*Footnote Reference†

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Credit QualityFootnote Reference*Footnote Reference†

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Country Weightings

Top Ten Holdings

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Country Weightings

Top Ten Holdings

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Country Weightings

Top Ten Holdings

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Country Weightings

Top Ten Holdings

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Credit QualityFootnote Reference*Footnote Reference†

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Credit QualityFootnote Reference*Footnote Reference†

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Credit QualityFootnote Reference*Footnote Reference†

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Credit QualityFootnote Reference*Footnote Reference†

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Credit QualityFootnote Reference*Footnote Reference†

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Credit QualityFootnote Reference*Footnote Reference†

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Key Fund Statistics

Industry Summary

Credit QualityFootnote Reference*Footnote Reference†

Material Fund Changes

What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}

Credit Quality^{Footnote Reference*}^{Footnote Reference†}