Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	SIT MUTUAL FUNDS INC
Prospectus Date	rr_ProspectusDate	Nov. 01, 2016
SIT MUTUAL FUNDS INC | Sit Small Cap Dividend Growth Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	SUMMARY INFORMATION SIT SMALL CAP DIVIDEND GROWTH FUND
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund primarily seeks to provide current income that exceeds the Fund’s benchmark index and that grows over a period of years.
Objective, Secondary [Text Block]	rr_ObjectiveSecondaryTextBlock	Secondarily the Fund seeks long-term capital appreciation.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transactions costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 26.43% (both classes) of the average value of the portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	26.43%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	The total annual fund operating expenses do not correlate to the ratio of expenses to average net assets shown in the Fund's Financial Highlights, which does not include Acquired Fund Fees and Expenses.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in the Fund for the time periods indicated, that your investment has a 5% return each year, that the Fund’s operating expenses remain the same, and that you redeem all of your shares at the end of those periods. Although your actual costs and returns may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks to achieve its objectives by investing, under normal market conditions, at least 80% of its net assets in small cap dividend-paying common stocks. The Fund may invest the balance of its assets in preferred stocks, convertible bonds, U.S. Treasury securities (including Treasury bills, notes and bonds), closed-end investment companies, and master limited partnerships. The Fund’s benchmark index to be used in connection with the Fund’s investment objective is the Russell 2000® Index, and such benchmark index may be changed from time to time with approval of the Fund’s Board of Directors. The Russell 2000® Index measures the performance of the 2,000 smallest companies in the Russell 3000® Index (which is made up of the 3,000 largest U.S. companies based on total market capitalization). Small cap stocks are issued by companies with capitalizations at the time of purchase of up to $3 billion, or up to the market capitalization of the largest company included in the Russell 2000® Index measured at the end of the previous twelve months. As of September 30, 2016, the market capitalization of the largest company included in the Russell 2000® Index measured at the end of the previous twelve months was $14.6 billion. The Adviser invests in dividend paying, growth-oriented companies it believes exhibit the potential for growth and growing dividend payments. The Adviser believes that a company’s earnings growth is a primary determinant of its potential long-term return, and that a record of increasing dividend payments is a strong indicator of financial health and growth prospects. The Adviser considers several factors in its evaluation of a company’s potential for above average long-term earnings, revenue, and dividend growth, including: a record of paying dividends, strong prospects for growing dividend payments indicated in part by growing earnings and cash flow, unique product or service, growing product demand, dominant and growing market share, management experience and capabilities, and strong financial condition. Since stocks that pay dividends tend to be less volatile and may not experience the same capital appreciation as stocks that don’t pay dividends, the Fund’s diversified portfolio of dividend paying stocks is expected to have lower volatility than that of the Russell 2000® Index, but with a higher dividend yield and greater prospects for dividend growth. The Fund may invest up to 20% of its net assets in securities of issuers domiciled outside the U.S. When selling equity securities for the Fund, the Adviser considers several factors, including changes in a company’s fundamentals, anticipated earnings, anticipated dividend payments and financial position.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	You could lose money by investing in the Fund. The principal risks of investing in the Fund are as follows: Dividend Paying Company Risk: The Fund’s income objective may limit its ability to appreciate during a broad market advance because dividend paying stocks may not experience the same capital appreciation as non-dividend paying stocks. In addition, stocks held by the Fund may reduce or stop paying dividends which could affect the Fund’s ability to generate income. Growth Style Investing Risk: Different types of stocks tend to shift into and out of favor with stock market investors depending on market and economic conditions. The Fund invests in growth style stocks. The Fund’s performance may at times be better or worse than the performance of funds that focus on other types of stocks or that have a broader investment style. International Investing Risk: Because the Fund may invest in foreign securities, there is an international investing risk. International investing involves risks not typically associated with investing in U.S. securities which may adversely affect the Fund’s investment. These risks include currency risk, foreign securities market risk, foreign tax risk, information risk, investment restriction risk, and political and economic risks. Management Risk: A strategy used by the investment management team may not produce the intended results. Market Risk: The market value of securities may fall or fail to rise. Market risk may affect a single issuer, sector of the economy, or the market as a whole. The market value of securities may fluctuate, sometimes rapidly and unpredictably. New Fund Risk: The Fund’s inception is March 31, 2015. There can be no assurance that the Fund will grow to or maintain an economically viable size, in which case the Board of Directors may determine to liquidate the Fund. Small Stock Risk: Stocks of smaller companies involve substantial risk. Prices of small cap stocks may be subject to more abrupt or erratic market movements than stocks of larger, more established companies. Additionally, for certain small cap stocks, there may also be limited liquidity or trading opportunities at a favorable price or time.
Risk Lose Money [Text]	rr_RiskLoseMoney	You could lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	HISTORICAL PERFORMANCE
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The Fund’s inception is March 31, 2015, and therefore there is no annual total return or average annual total return information to report at this time. The Fund’s year-to-date return as of 9/30/16 (not annualized) was 12.35%. The Fund’s best quarter was 4.53% (2Q16) and worst quarter was -7.93% (3Q15). For current performance information, please call 1-800-332-5580 or visit www. sitinvest.com. The Fund’s past performance does not necessarily indicate how it will perform in the future.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	The Fund’s inception is March 31, 2015, and therefore there is no annual total return or average annual total return information to report at this time.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-332-5580
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www. sitinvest.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance does not necessarily indicate how it will perform in the future.
SIT MUTUAL FUNDS INC | Sit Small Cap Dividend Growth Fund | Class I
Risk/Return:	rr_RiskReturnAbstract
Redemption Fee (as a percentage of amount redeemed only on shares held for less than 30 days)	rr_RedemptionFeeOverRedemption	2.00%
Management Fees	rr_ManagementFeesOverAssets	1.25%
Distribution (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.08%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.33%	[1]
1 Year	rr_ExpenseExampleYear01	$ 136
3 Years	rr_ExpenseExampleYear03	424
5 Years	rr_ExpenseExampleYear05	733
10 Years	rr_ExpenseExampleYear10	$ 1,609
Year to Date Return, Label	rr_YearToDateReturnLabel	year-to-date return
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	12.35%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	best quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2016
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	4.53%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	worst quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2015
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(7.93%)
SIT MUTUAL FUNDS INC | Sit Small Cap Dividend Growth Fund | Class S
Risk/Return:	rr_RiskReturnAbstract
Redemption Fee (as a percentage of amount redeemed only on shares held for less than 30 days)	rr_RedemptionFeeOverRedemption	2.00%
Management Fees	rr_ManagementFeesOverAssets	1.25%
Distribution (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.08%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.58%	[1]
1 Year	rr_ExpenseExampleYear01	$ 162
3 Years	rr_ExpenseExampleYear03	502
5 Years	rr_ExpenseExampleYear05	866
10 Years	rr_ExpenseExampleYear10	$ 1,889

[1] The total annual fund operating expenses do not correlate to the ratio of expenses to average net assets shown in the Fund's Financial Highlights, which does not include Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses represent fees and expenses incurred indirectly by the Fund as a result of its investment in shares of investment companies.