Investment Strategy	Mar. 31, 2026
Sit Quality Income Fund
Prospectus [Line Items]
Strategy [Heading]	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	The Fund seeks to achieve its objective by investing under normal circumstances at least 80% of its assets in debt securities issued by the U.S. Government and its agencies, debt securities issued by corporations, and mortgage and other asset-backed securities. The Fund invests at least 50% of its assets in U.S. government debt securities, which are securities issued, guaranteed or insured by the U.S. government, its agencies or instrumentalities. The balance of the Fund’s assets will be invested in investment grade debt securities issued by corporations and municipalities, and mortgage and other asset-backed securities. Investment grade debt securities are rated at the time of purchase within the top four rating categories by a Nationally Recognized Statistical Rating Organization or of comparable quality as determined by the Adviser. The Fund’s dollar-weighted average portfolio quality is expected to be “A” or better. The U.S. government securities in which the Fund will invest include direct obligations of the U.S. Treasury and securities issued or guaranteed by federal agencies or authorities and U.S. government-sponsored instrumentalities or enterprises. The Fund will invest in pass-through securities. Pass-through securities include mortgage-backed securities such as those issued by Government National Mortgage Association (GNMA), Federal National Mortgage Association (FNMA) and Federal Home Loan Mortgage Corporation (FHLMC). GNMA is an agency of the U.S. government and its securities are backed by the full faith and credit of the U.S. government. FNMA and FHLMC are U.S. government sponsored enterprises and their securities are backed by their credit. The Fund may invest in debt securities described herein that have not been registered for sale under the Securities Act of 1933 pursuant to Rule 144A (Rule 144A securities) which are determined to be liquid by the Adviser. The Fund may invest in open‑end investment companies (mutual funds) and closed‑end investment companies which invest in the same types of securities in which the Fund may invest directly. In selecting securities for the Fund, the Adviser seeks securities providing relatively high current income. In making purchase and sales decisions for the Fund, the Adviser considers its economic outlook and interest rate forecast, as well as its evaluation of a security’s credit quality, yield, maturity, liquidity and the security’s sector. The Adviser attempts to maintain an average effective duration for the portfolio of approximately 0 to 3 years. The Adviser’s duration target within this range is based on its interest rate forecast. Duration is a measure of total price sensitivity relative to changes in interest rates. For example, if interest rates rise by 1%, the market value of a security with an effective duration of 3 years would decrease by 3%, with all other factors being constant. Portfolios with shorter durations are typically less sensitive to changes in interest rates. The Adviser currently hedges the Fund’s duration by investing in interest rate futures and options, but not in excess of 5% of the Fund’s net assets. The Fund’s dollar-weighted average maturity will, under normal market conditions, range between 5 and 10 years. However, since the Fund’s securities are subject to various types of call provisions which make their expected average lives shorter than their stated maturity dates, the Adviser believes that the Fund’s average effective duration is a more accurate measure of the Fund’s price sensitivity to changes in interest rates than the Fund’s dollar-weighted average maturity.
Summary of Definition of Rule 35d-1 Term in Fund Name [Text Block]	The Fund invests at least 50% of its assets in U.S. government debt securities, which are securities issued, guaranteed or insured by the U.S. government, its agencies or instrumentalities. The balance of the Fund’s assets will be invested in investment grade debt securities issued by corporations and municipalities, and mortgage and other asset-backed securities. Investment grade debt securities are rated at the time of purchase within the top four rating categories by a Nationally Recognized Statistical Rating Organization or of comparable quality as determined by the Adviser. The Fund’s dollar-weighted average portfolio quality is expected to be “A” or better.
Summary of Selection Criteria for Rule 35d-1 Term in Fund Name [Text Block]	The U.S. government securities in which the Fund will invest include direct obligations of the U.S. Treasury and securities issued or guaranteed by federal agencies or authorities and U.S. government-sponsored instrumentalities or enterprises. The Fund will invest in pass-through securities. Pass-through securities include mortgage-backed securities such as those issued by Government National Mortgage Association (GNMA), Federal National Mortgage Association (FNMA) and Federal Home Loan Mortgage Corporation (FHLMC). GNMA is an agency of the U.S. government and its securities are backed by the full faith and credit of the U.S. government. FNMA and FHLMC are U.S. government sponsored enterprises and their securities are backed by their credit.
Rule 35d-1 Eighty Percent Investment Policy [Text Block]	The Fund seeks to achieve its objective by investing under normal circumstances at least 80% of its assets in debt securities issued by the U.S. Government and its agencies, debt securities issued by corporations, and mortgage and other asset-backed securities.
Sit Tax-Free Income Fund
Prospectus [Line Items]
Strategy [Heading]	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	The Fund seeks to achieve its objective by investing primarily in municipal securities that generate interest income that is exempt from regular federal income tax. Under normal circumstances, the Fund invests 100% (and, as a fundamental policy, no less than 80%) of its net assets in such tax‑exempt municipal securities plus the amount of any borrowings for investment purposes. The Fund may invest up to 20% of its assets in securities that generate interest income subject to federal alternative minimum tax (“AMT”). Investors subject to AMT treat the Fund’s income subject to AMT as an item of tax preference in computing their alternative minimum taxable income. Municipal securities are debt obligations issued by or for U.S. states, territories, and possessions and the District of Columbia, and their political subdivisions, agencies, and instrumentalities. The Fund invests both in revenue bonds, which are backed by and payable only from the revenues derived from a specific facility or specific revenue source, and in general obligation bonds, which are secured by the full faith, credit and taxation power of the issuing municipality. The Fund invests a significant portion of its assets in housing-related securities, such as obligations of municipal housing authorities, which include single family and multi-family mortgage revenue bonds; revenue bonds of health care-related facilities; and revenue bonds of educational institutions, which include higher education institutions, public, private, and charter schools, and student loan-backed bonds. The Fund primarily invests in securities rated investment-grade at the time of purchase or, if unrated, determined to be of comparable quality by Sit Investment Associates, Inc. (the “Adviser”). Investment-grade securities are rated within the four highest grades by the major rating agencies. However, the Fund may invest up to 30% of its assets in municipal securities rated below investment grade (commonly referred to as junk bonds) or determined to be of comparable quality by the Adviser, but the Fund may not invest in securities rated lower than B3 by Moody’s Investors Service, or B‑ by S&P Global Ratings or Fitch Ratings, or, if unrated, determined by the Adviser to be of comparable quality. The Fund may invest in debt securities described herein that have not been registered for sale under the Securities Act of 1933 pursuant to Rule 144A (Rule 144A securities) which are determined to be liquid by the Adviser. The Fund may invest in open‑end investment companies (mutual funds) and closed‑end investment companies which invest in the same types of securities in which the Fund may invest directly. In selecting securities for the Fund, the Adviser seeks securities providing high tax‑exempt income. The Adviser’s economic outlook and interest rate forecast, as well as its evaluation of a security’s structure, credit quality, yield, maturity, and liquidity, are all factors considered when making investment decisions. The Adviser attempts to maintain an average effective duration for the portfolio of approximately 3 to 8 years. Duration is a measure of total price sensitivity relative to changes in interest rates. For example, if interest rates rise by 1%, the market value of a security with an effective duration of 3 years would decrease by 3%, with all other factors being constant. Portfolios with longer durations are typically more sensitive to changes in interest rates. The Adviser may hedge the Fund’s duration by investing in interest rate futures and options, but not in excess of 5% of the Fund’s net assets. The Fund’s dollar-weighted average maturity will, under normal market conditions, range between 10 and 25 years. However, since the Fund’s securities are subject to various types of call provisions which make their expected average lives shorter than their stated maturity dates, the Adviser believes that the Fund’s average effective duration is a more accurate measure of the Fund’s price sensitivity to changes in interest rates than the Fund’s dollar-weighted average maturity.
Summary of Definition of Rule 35d-1 Term in Fund Name [Text Block]	The Fund may invest up to 20% of its assets in securities that generate interest income subject to federal alternative minimum tax (“AMT”). Investors subject to AMT treat the Fund’s income subject to AMT as an item of tax preference in computing their alternative minimum taxable income. Municipal securities are debt obligations issued by or for U.S. states, territories, and possessions and the District of Columbia, and their political subdivisions, agencies, and instrumentalities.
Summary of Selection Criteria for Rule 35d-1 Term in Fund Name [Text Block]	The Fund primarily invests in securities rated investment-grade at the time of purchase or, if unrated, determined to be of comparable quality by Sit Investment Associates, Inc. (the “Adviser”). Investment-grade securities are rated within the four highest grades by the major rating agencies. However, the Fund may invest up to 30% of its assets in municipal securities rated below investment grade (commonly referred to as junk bonds) or determined to be of comparable quality by the Adviser, but the Fund may not invest in securities rated lower than B3 by Moody’s Investors Service, or B‑ by S&P Global Ratings or Fitch Ratings, or, if unrated, determined by the Adviser to be of comparable quality.
Rule 35d-1 Eighty Percent Investment Policy [Text Block]	The Fund seeks to achieve its objective by investing primarily in municipal securities that generate interest income that is exempt from regular federal income tax. Under normal circumstances, the Fund invests 100% (and, as a fundamental policy, no less than 80%) of its net assets in such tax‑exempt municipal securities plus the amount of any borrowings for investment purposes.
Sit Minnesota Tax-Free Income Fund
Prospectus [Line Items]
Strategy [Heading]	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	The Fund seeks to achieve its objective by investing primarily in municipal securities that generate interest income that is exempt from regular federal income tax and Minnesota regular personal income tax. Under normal circumstances, the Fund invests 100% (and, as a fundamental policy, no less than 80%) of its net assets in such tax‑exempt municipal securities plus the amount of any borrowings for investment purposes. The Fund may invest up to 20% of its assets in securities that generate interest income subject to both Minnesota and federal alternative minimum tax (“AMT”). Investors subject to AMT treat the Fund’s income subject to AMT as an item of tax preference in computing their alternative minimum taxable income. The Fund substantially invests in municipal securities issued by the state of Minnesota and its political subdivisions. The Fund invests in both general obligation bonds, which are secured by the full faith, credit and taxation power of the issuing municipality, and in revenue bonds, which are backed by and payable only from the revenues derived from a specific facility or specific revenue source. The Fund invests a significant portion of its assets in housing-related securities, such as obligations of municipal housing authorities, which include single family and multi-family mortgage revenue bonds; revenue bonds of health care-related facilities; and revenue bonds of educational institutions, which include higher education institutions, public, private, and charter schools, and student loan-backed bonds. The Fund primarily invests in securities rated investment-grade at the time of purchase or, if unrated, determined to be of comparable quality by Sit Investment Associates, Inc. (the “Adviser”). Investment-grade securities are rated within the four highest grades by the major rating agencies. However, the Fund may invest up to 30% of its assets in municipal securities rated below investment-grade (commonly referred to as junk bonds) or determined to be of comparable quality by the Adviser, but the Fund may not invest in securities rated lower than B3 by Moody’s Investors Service, or B‑ by S&P Global Ratings or Fitch Ratings or, if unrated, determined by the Adviser to be of comparable quality. The Fund may invest in open‑end investment companies (mutual funds) and closed‑end investment companies which invest in the same types of securities in which the Fund may invest directly. In selecting securities for the Fund, the Adviser seeks securities providing high current tax‑exempt income. In making purchase and sales decisions for the Fund, the Adviser considers its economic outlook and interest rate forecast, as well as its evaluation of a security’s structure, credit quality, yield, maturity, and liquidity. The Adviser attempts to maintain an average effective duration for the portfolio of approximately 3 to 8 years. Duration is a measure of total price sensitivity relative to changes in interest rates. For example, if interest rates rise by 1%, the market value of a security with an effective duration of 3 years would decrease by 3%, with all other factors being constant. Portfolios with longer durations are typically more sensitive to changes in interest rates. The Adviser currently hedges the Fund’s duration by investing in interest rate futures and options, but not in excess of 5% of the Fund’s net assets. The Fund’s dollar-weighted average maturity will, under normal market conditions, range between 10 and 20 years. However, since the Fund’s securities are subject to various types of call provisions which make their expected average lives shorter than their stated maturity dates, the Adviser believes that the Fund’s average effective duration is a more accurate measure of the Fund’s price sensitivity to changes in interest rates than the Fund’s dollar-weighted average maturity.
Summary of Definition of Rule 35d-1 Term in Fund Name [Text Block]	The Fund may invest up to 20% of its assets in securities that generate interest income subject to both Minnesota and federal alternative minimum tax (“AMT”). Investors subject to AMT treat the Fund’s income subject to AMT as an item of tax preference in computing their alternative minimum taxable income.
Summary of Selection Criteria for Rule 35d-1 Term in Fund Name [Text Block]	The Fund primarily invests in securities rated investment-grade at the time of purchase or, if unrated, determined to be of comparable quality by Sit Investment Associates, Inc. (the “Adviser”). Investment-grade securities are rated within the four highest grades by the major rating agencies. However, the Fund may invest up to 30% of its assets in municipal securities rated below investment-grade (commonly referred to as junk bonds) or determined to be of comparable quality by the Adviser, but the Fund may not invest in securities rated lower than B3 by Moody’s Investors Service, or B‑ by S&P Global Ratings or Fitch Ratings or, if unrated, determined by the Adviser to be of comparable quality.
Rule 35d-1 Eighty Percent Investment Policy [Text Block]	The Fund seeks to achieve its objective by investing primarily in municipal securities that generate interest income that is exempt from regular federal income tax and Minnesota regular personal income tax. Under normal circumstances, the Fund invests 100% (and, as a fundamental policy, no less than 80%) of its net assets in such tax‑exempt municipal securities plus the amount of any borrowings for investment purposes.

Investment Strategy

Mar. 31, 2026

PRINCIPAL INVESTMENT STRATEGIES

The Fund seeks to achieve its objective by investing under normal circumstances at least 80% of its assets in debt securities issued by the U.S. Government and its agencies, debt securities issued by corporations, and mortgage and other asset-backed securities.

The Fund invests at least 50% of its assets in U.S. government debt securities, which are securities issued, guaranteed or insured by the U.S. government, its agencies or instrumentalities. The balance of the Fund’s assets will be invested in investment grade debt securities issued by corporations and municipalities, and mortgage and other asset-backed securities. Investment grade debt securities are rated at the time of purchase within the top four rating categories by a Nationally Recognized Statistical Rating Organization or of comparable quality as determined by the Adviser. The Fund’s dollar-weighted average portfolio quality is expected to be “A” or better.

The U.S. government securities in which the Fund will invest include direct obligations of the U.S. Treasury and securities issued or guaranteed by federal agencies or authorities and U.S. government-sponsored instrumentalities or enterprises. The Fund will invest in pass-through securities. Pass-through securities include mortgage-backed securities such as those issued by Government National Mortgage Association (GNMA), Federal National Mortgage Association (FNMA) and Federal Home Loan Mortgage Corporation (FHLMC). GNMA is an agency of the U.S. government and its securities are backed by the full faith and credit of the U.S. government. FNMA and FHLMC are U.S. government sponsored enterprises and their securities are backed by their credit.

The Fund may invest in debt securities described herein that have not been registered for sale under the Securities Act of 1933 pursuant to Rule 144A (Rule 144A securities) which are determined to be liquid by the Adviser.

The Fund may invest in open‑end investment companies (mutual funds) and closed‑end investment companies which invest in the same types of securities in which the Fund may invest directly.

In selecting securities for the Fund, the Adviser seeks securities providing relatively high current income. In making purchase and sales decisions for the Fund, the Adviser considers its economic outlook and interest rate forecast, as well as its evaluation of a security’s credit quality, yield, maturity, liquidity and the security’s sector.

The Adviser attempts to maintain an average effective duration for the portfolio of approximately 0 to 3 years. The Adviser’s duration target within this range is based on its interest rate forecast. Duration is a measure of total price sensitivity relative to changes in interest rates. For example, if interest rates rise by 1%, the market value of a security with an effective duration of 3 years would decrease by 3%, with all other factors being constant. Portfolios with shorter durations are typically less sensitive to changes in interest rates. The Adviser currently hedges the Fund’s duration by investing in interest rate futures and options, but not in excess of 5% of the Fund’s net assets.

The Fund’s dollar-weighted average maturity will, under normal market conditions, range between 5 and 10 years. However, since the Fund’s securities are subject to various types of call provisions which make their expected average lives shorter than their stated maturity dates, the Adviser believes that the Fund’s average effective duration is a more accurate measure of the Fund’s price sensitivity to changes in interest rates than the Fund’s dollar-weighted average maturity.

Summary of Definition of Rule 35d-1 Term in Fund Name [Text Block]

Summary of Selection Criteria for Rule 35d-1 Term in Fund Name [Text Block]

Rule 35d-1 Eighty Percent Investment Policy [Text Block]

Sit Tax-Free Income Fund

Prospectus [Line Items]

Strategy [Heading]

PRINCIPAL INVESTMENT STRATEGIES

Strategy Narrative [Text Block]

The Fund seeks to achieve its objective by investing primarily in municipal securities that generate interest income that is exempt from regular federal income tax. Under normal circumstances, the Fund invests 100% (and, as a fundamental policy, no less than 80%) of its net assets in such tax‑exempt municipal securities plus the amount of any borrowings for investment purposes. The Fund may invest up to 20% of its assets in securities that generate interest income subject to federal alternative minimum tax (“AMT”). Investors subject to AMT treat the Fund’s income subject to AMT as an item of tax preference in computing their alternative minimum taxable income. Municipal securities are debt obligations issued by or for U.S. states, territories, and possessions and the District of Columbia, and their political subdivisions, agencies, and instrumentalities.

The Fund invests both in revenue bonds, which are backed by and payable only from the revenues derived from a specific facility or specific revenue source, and in general obligation bonds, which are secured by the full faith, credit and taxation power of the issuing municipality. The Fund invests a significant portion of its assets in housing-related securities, such as obligations of municipal housing authorities, which include single family and multi-family mortgage revenue bonds; revenue bonds of health care-related facilities; and revenue bonds of educational institutions, which include higher education institutions, public, private, and charter schools, and student loan-backed bonds.

The Fund primarily invests in securities rated investment-grade at the time of purchase or, if unrated, determined to be of comparable quality by Sit Investment Associates, Inc. (the “Adviser”). Investment-grade securities are rated within the four highest grades by the major rating agencies. However, the Fund may invest up to 30% of its assets in municipal securities rated below investment grade (commonly referred to as junk bonds) or determined to be of comparable quality by the Adviser, but the Fund may not invest in securities rated lower than B3 by Moody’s Investors Service, or B‑ by S&P Global Ratings or Fitch Ratings, or, if unrated, determined by the Adviser to be of comparable quality.

The Fund may invest in open‑end investment companies (mutual funds) and closed‑end investment companies which invest in the same types of securities in which the Fund may invest directly.

In selecting securities for the Fund, the Adviser seeks securities providing high tax‑exempt income. The Adviser’s economic outlook and interest rate forecast, as well as its evaluation of a security’s structure, credit quality, yield, maturity, and liquidity, are all factors considered when making investment decisions.

The Adviser attempts to maintain an average effective duration for the portfolio of approximately 3 to 8 years. Duration is a measure of total price sensitivity relative to changes in interest rates. For example, if interest rates rise by 1%, the market value of a security with an effective duration of 3 years would decrease by 3%, with all other factors being constant. Portfolios with longer durations are typically more sensitive to changes in interest rates. The Adviser may hedge the Fund’s duration by investing in interest rate futures and options, but not in excess of 5% of the Fund’s net assets.

The Fund’s dollar-weighted average maturity will, under normal market conditions, range between 10 and 25 years. However, since the Fund’s securities are subject to various types of call provisions which make their expected average lives shorter than their stated maturity dates, the Adviser believes that the Fund’s average effective duration is a more accurate measure of the Fund’s price sensitivity to changes in interest rates than the Fund’s dollar-weighted average maturity.

Summary of Definition of Rule 35d-1 Term in Fund Name [Text Block]

The Fund may invest up to 20% of its assets in securities that generate interest income subject to federal alternative minimum tax (“AMT”). Investors subject to AMT treat the Fund’s income subject to AMT as an item of tax preference in computing their alternative minimum taxable income. Municipal securities are debt obligations issued by or for U.S. states, territories, and possessions and the District of Columbia, and their political subdivisions, agencies, and instrumentalities.

Summary of Selection Criteria for Rule 35d-1 Term in Fund Name [Text Block]

Rule 35d-1 Eighty Percent Investment Policy [Text Block]

Sit Minnesota Tax-Free Income Fund

Prospectus [Line Items]

Strategy [Heading]

PRINCIPAL INVESTMENT STRATEGIES

Strategy Narrative [Text Block]

The Fund seeks to achieve its objective by investing primarily in municipal securities that generate interest income that is exempt from regular federal income tax and Minnesota regular personal income tax. Under normal circumstances, the Fund invests 100% (and, as a fundamental policy, no less than 80%) of its net assets in such tax‑exempt municipal securities plus the amount of any borrowings for investment purposes. The Fund may invest up to 20% of its assets in securities that generate interest income subject to both Minnesota and federal alternative minimum tax (“AMT”). Investors subject to AMT treat the Fund’s income subject to AMT as an item of tax preference in computing their alternative minimum taxable income.

The Fund substantially invests in municipal securities issued by the state of Minnesota and its political subdivisions. The Fund invests in both general obligation bonds, which are secured by the full faith, credit and taxation power of the issuing municipality, and in revenue bonds, which are backed by and payable only from the revenues derived from a specific facility or specific revenue source. The Fund invests a significant portion of its assets in housing-related securities, such as obligations of municipal housing authorities, which include single family and multi-family mortgage revenue bonds; revenue bonds of health care-related facilities; and revenue bonds of educational institutions, which include higher education institutions, public, private, and charter schools, and student loan-backed bonds.

The Fund primarily invests in securities rated investment-grade at the time of purchase or, if unrated, determined to be of comparable quality by Sit Investment Associates, Inc. (the “Adviser”). Investment-grade securities are rated within the four highest grades by the major rating agencies. However, the Fund may invest up to 30% of its assets in municipal securities rated below investment-grade (commonly referred to as junk bonds) or determined to be of comparable quality by the Adviser, but the Fund may not invest in securities rated lower than B3 by Moody’s Investors Service, or B‑ by S&P Global Ratings or Fitch Ratings or, if unrated, determined by the Adviser to be of comparable quality.

The Fund may invest in open‑end investment companies (mutual funds) and closed‑end investment companies which invest in the same types of securities in which the Fund may invest directly.

In selecting securities for the Fund, the Adviser seeks securities providing high current tax‑exempt income. In making purchase and sales decisions for the Fund, the Adviser considers its economic outlook and interest rate forecast, as well as its evaluation of a security’s structure, credit quality, yield, maturity, and liquidity.

The Adviser attempts to maintain an average effective duration for the portfolio of approximately 3 to 8 years. Duration is a measure of total price sensitivity relative to changes in interest rates. For example, if interest rates rise by 1%, the market value of a security with an effective duration of 3 years would decrease by 3%, with all other factors being constant. Portfolios with longer durations are typically more sensitive to changes in interest rates. The Adviser currently hedges the Fund’s duration by investing in interest rate futures and options, but not in excess of 5% of the Fund’s net assets.

The Fund’s dollar-weighted average maturity will, under normal market conditions, range between 10 and 20 years. However, since the Fund’s securities are subject to various types of call provisions which make their expected average lives shorter than their stated maturity dates, the Adviser believes that the Fund’s average effective duration is a more accurate measure of the Fund’s price sensitivity to changes in interest rates than the Fund’s dollar-weighted average maturity.

Summary of Definition of Rule 35d-1 Term in Fund Name [Text Block]

The Fund may invest up to 20% of its assets in securities that generate interest income subject to both Minnesota and federal alternative minimum tax (“AMT”). Investors subject to AMT treat the Fund’s income subject to AMT as an item of tax preference in computing their alternative minimum taxable income.

Summary of Selection Criteria for Rule 35d-1 Term in Fund Name [Text Block]

The Fund primarily invests in securities rated investment-grade at the time of purchase or, if unrated, determined to be of comparable quality by Sit Investment Associates, Inc. (the “Adviser”). Investment-grade securities are rated within the four highest grades by the major rating agencies. However, the Fund may invest up to 30% of its assets in municipal securities rated below investment-grade (commonly referred to as junk bonds) or determined to be of comparable quality by the Adviser, but the Fund may not invest in securities rated lower than B3 by Moody’s Investors Service, or B‑ by S&P Global Ratings or Fitch Ratings or, if unrated, determined by the Adviser to be of comparable quality.

Rule 35d-1 Eighty Percent Investment Policy [Text Block]