| Label | Element | Value | ||||
|---|---|---|---|---|---|---|
| Nebraska Municipal Fund | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk/Return [Heading] | rr_RiskReturnHeading | NEBRASKA MUNICIPAL FUND—FUND SUMMARY | ||||
| Objective [Heading] | rr_ObjectiveHeading | Investment Objective | ||||
| Objective, Primary [Text Block] | rr_ObjectivePrimaryTextBlock | The Nebraska Municipal Fund (the “Fund”) seeks the highest level of current income that is exempt from federal and Nebraska personal income taxes and is consistent with preservation of capital. |
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| 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, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts with respect to purchases of Class A shares of the Fund if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other funds in the Integrity/Viking family of funds. More information about these and other discounts is available from your financial professional and in “The Shares Offered; Class A Shares” and “How to Buy Shares; Investor Services” on pages 44 and 50, respectively, of the Fund’s prospectus, Appendix A of the Fund’s prospectus, and “Buying and Selling Shares” on page B-28 of the Fund’s statement of additional information. |
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| 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) | ||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | Nov. 29, 2025 | ||||
| Portfolio Turnover [Heading] | rr_PortfolioTurnoverHeading | Portfolio Turnover— | ||||
| Portfolio Turnover [Text Block] | rr_PortfolioTurnoverTextBlock | The Fund pays transaction 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 or in the Example, affect the Fund’s performance. During the most recent fiscal period, the Fund’s portfolio turnover rate was 79.45% of the average value of its portfolio. |
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| Portfolio Turnover, Rate | rr_PortfolioTurnoverRate | 79.45% | ||||
| Expense Breakpoint Discounts [Text] | rr_ExpenseBreakpointDiscounts | You may qualify for sales charge discounts with respect to purchases of Class A shares of the Fund if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other funds in the Integrity/Viking family of funds. | ||||
| Expense Breakpoint, Minimum Investment Required [Amount] | rr_ExpenseBreakpointMinimumInvestmentRequiredAmount | $ 50,000 | ||||
| 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 costs of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year, that the Fund’s operating expenses remain the same, and that the contractual expense limitation agreement remains in place for the first year. Although your actual costs may be higher or lower, based on these assumptions your costs would be: |
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| Strategy [Heading] | rr_StrategyHeading | Principal Investment Strategies | ||||
| Strategy Narrative [Text Block] | rr_StrategyNarrativeTextBlock | To pursue its objective, the Fund normally invests at least 80% of its net assets (including any borrowings for investment purposes) in municipal securities that pay interest free from (a) federal income taxes, including the federal alternative minimum tax, and (b) Nebraska personal income taxes.
Municipal bonds are debt securities issued by or on behalf of states, territories, and possessions of the United States and their political subdivisions, agencies, authorities, and instrumentalities. The two general classifications of municipal bonds are “general obligation” and “revenue” bonds. General obligation bonds are secured by the issuer’s pledge of its faith, credit, and taxing power for the payment of principal and interest. Revenue bonds are payable only from the revenues derived from a particular facility or class of facilities or, in some cases, from the proceeds of a special excise tax or other specific revenue source.
The investment manager actively manages the Fund’s portfolio by selecting securities that it believes will provide the best balance between risk and return within the Fund’s range of allowable investments. The investment manager will consider selling a security with deteriorating credit or limited upside potential compared to other available bonds.
The Fund may invest up to 30% of its net assets in U.S. territorial obligations (including qualifying obligations of Puerto Rico, the U.S. Virgin Islands, and Guam), the interest on which is exempt from federal and Nebraska personal income taxes. The Fund may invest up to 20% of its net assets in private activity bonds (which are revenue bonds that finance privately operated facilities), the interest on which is a tax preference item for purposes of the federal alternative minimum tax.
The Fund may invest more than 25% of its net assets in municipal securities that finance similar types of projects, such as education, healthcare, housing, industrial development, transportation, utilities, or pollution control. Economic, business, political, or other changes can affect all securities of a similar type.
All of the municipal securities in which the Fund invests are rated investment grade (BBB- or higher) at the time of purchase by a nationally recognized statistical rating service such as S&P Global Ratings or Moody’s Investors Service, Inc. or are of comparable quality as determined by the Fund’s investment manager. If, subsequent to the purchase of a municipal security, the rating of a municipal security falls below investment grade, the Fund will not be required to dispose of the security.
Under normal circumstances, the Fund will maintain an average stated maturity at between five and twenty-five years.
The Fund is non-diversified and therefore may invest a greater percentage of its assets in securities of a more limited number of issuers compared to a diversified mutual fund. |
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| Strategy Portfolio Concentration [Text] | rr_StrategyPortfolioConcentration | Under normal circumstances, the Fund will maintain an average stated maturity at between five and twenty-five years. | ||||
| Risk [Heading] | rr_RiskHeading | Principal Risks | ||||
| Bar Chart and Performance Table [Heading] | rr_BarChartAndPerformanceTableHeading | Fund Performance | ||||
| Performance Narrative [Text Block] | rr_PerformanceNarrativeTextBlock | The following bar chart and table provide some indication of the risks of investing in the Fund. The Fund’s past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available at www.integrityvikingfunds.com or by calling 800-276-1262. |
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| Performance Information Illustrates Variability of Returns [Text] | rr_PerformanceInformationIllustratesVariabilityOfReturns | The bar chart below shows the variability of the Fund’s performance from year to year for Class A shares. The bar chart and highest/lowest quarterly returns that follow do not reflect sales charges, and if these charges were reflected, the returns would be less than those shown. | ||||
| Performance Availability Phone [Text] | rr_PerformanceAvailabilityPhone | 800-276-1262 | ||||
| Performance Availability Website Address [Text] | rr_PerformanceAvailabilityWebSiteAddress | www.integrityvikingfunds.com | ||||
| Performance Past Does Not Indicate Future [Text] | rr_PerformancePastDoesNotIndicateFuture | The Fund’s past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. | ||||
| Bar Chart [Heading] | rr_BarChartHeading | Per Share Total Return per Calendar Year | ||||
| Bar Chart Does Not Reflect Sales Loads [Text] | rr_BarChartDoesNotReflectSalesLoads | The bar chart and highest/lowest quarterly returns that follow do not reflect sales charges, and if these charges were reflected, the returns would be less than those shown. | ||||
| Bar Chart Closing [Text Block] | rr_BarChartClosingTextBlock | During the ten-year period shown in the bar chart, the highest return for a quarter was 6.82% (quarter ended December 31, 2023) and the lowest return for a quarter was -5.08% (quarter ended March 31, 2022). The Fund’s calendar year-to-date total return as of September 30, 2024 was 0.96%. |
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| Performance Table Heading | rr_PerformanceTableHeading | Average Annual Total Returns (for the periods ended December 31, 2023) | ||||
| Performance Table Uses Highest Federal Rate | rr_PerformanceTableUsesHighestFederalRate | After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. | ||||
| Performance Table One Class of after Tax Shown [Text] | rr_PerformanceTableOneClassOfAfterTaxShown | After-tax returns are shown for Class A shares of the Fund only; after-tax returns for Class I shares will vary. | ||||
| Performance Table Narrative | rr_PerformanceTableNarrativeTextBlock | The table below shows the Fund’s average annual total returns for 1, 5, and 10 years for Class A shares, and 1 year and since inception for Class I shares, and how they compare with those of a broad measure of market performance. The return information below reflects applicable sales charges. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. After-tax returns are shown for Class A shares of the Fund only; after-tax returns for Class I shares will vary. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown, and after-tax returns shown are not relevant to investors who hold their Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”). |
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| Nebraska Municipal Fund | Risk Lose Money [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | As with all mutual funds, there is the risk that you could lose money through your investment in the Fund. | ||||
| Nebraska Municipal Fund | Risk Nondiversified Status [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Because a relatively high percentage of the Fund’s assets may be invested in the securities of a limited number of issuers, the Fund’s portfolio may be more susceptible to any single event impacting the market value and returns of any one issuer than a diversified fund. | ||||
| Nebraska Municipal Fund | Risk Not Insured Depository Institution [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. | ||||
| Nebraska Municipal Fund | General market risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | General market risk. There is no assurance that the Fund will meet its investment objective. The prices of the securities in which the Fund invests may fluctuate as a result of market factors such as interest rates, credit spreads, or commodity prices, and the Fund’s share price and the value of your investment may change. Since the value of the Fund’s shares can go up or down, it is possible to lose money by investing in the Fund. | ||||
| Nebraska Municipal Fund | Non-diversified fund risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Non-diversified fund risk. Because a relatively high percentage of the Fund’s assets may be invested in the securities of a limited number of issuers, the Fund’s portfolio may be more susceptible to any single event impacting the market value and returns of any one issuer than a diversified fund. | ||||
| Nebraska Municipal Fund | Municipal securities risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Municipal securities risk. The values of municipal securities may be adversely affected by a number of factors, including adverse tax, legislative, political, or interest rate changes, general economic and market conditions, and the financial condition of the issuers of municipal securities. | ||||
| Nebraska Municipal Fund | Single state risks [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Single state risks. Because the Fund invests primarily in the municipal securities of Nebraska, it is particularly susceptible to any economic, political, or regulatory developments affecting a particular issuer or issuers of the Nebraska municipal securities in which it invests. Investing primarily in issues of a single state makes the Fund more sensitive to risks specific to the state. To the extent it invests a significant portion of its assets in the municipal securities of U.S. territories and possessions, the Fund will also be more sensitive to risks specific to such U.S. territories and possessions. In recent years, certain municipal bond issuers in Puerto Rico have been experiencing financial difficulties and rating agency downgrades. | ||||
| Nebraska Municipal Fund | Interest rate risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Interest rate risk. Interest rate risk is the risk that debt securities will decline in value because of changes in interest rates. As nominal interest rates rise, the value of certain debt securities held by the Fund is likely to decrease. Debt securities with longer maturities tend to be more sensitive to changes in interest rates, usually making them more volatile than securities with shorter maturities. | ||||
| Nebraska Municipal Fund | Income risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Income risk. The income from the Fund’s portfolio may decline because of falling market interest rates. This can result when the Fund invests the proceeds from new share sales, or from matured or called bonds, at market rates that are below the portfolio’s current earnings rate. | ||||
| Nebraska Municipal Fund | Liquidity risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Liquidity risk. Liquidity risk is the risk that the Fund may not be able to sell a holding in a timely manner at a desired price. Liquidity risk may result from the lack of an active market, the reduced number of traditional market participants, or the reduced capacity of traditional market participants to make a market in securities. The secondary market for certain municipal securities tends to be less developed and liquid than many other securities markets, which may adversely affect the Fund’s ability to sell such municipal securities at attractive prices. Moreover, inventories of municipal securities held by brokers and dealers have decreased in recent years, lessening their ability to make a market in these securities. This reduction in market making capacity has the potential to decrease the Fund’s ability to buy or sell bonds, and may increase bond price volatility and trading costs, particularly during periods of economic or market stress. As a result, the Fund may be forced to accept a lower price to sell a security, to sell other securities to raise cash, or to give up an investment opportunity, any of which could have a negative effect on performance. If the Fund needed to sell large blocks of securities to raise cash (such as to meet heavy shareholder redemptions), those sales could further reduce the securities’ prices and hurt performance. | ||||
| Nebraska Municipal Fund | Maturity risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Maturity risk. Generally, longer-term securities are more susceptible to changes in value as a result of interest rate changes than are shorter-term securities. | ||||
| Nebraska Municipal Fund | Credit risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Credit risk. Credit risk is the possibility that an issuer will be unable to make interest payments or repay principal. Changes in an issuer’s financial strength or in a security’s credit rating may affect its value. Securities supported by insurance or other credit enhancements also have the credit risk of the entity providing the insurance or other credit support. Changes in the credit quality of the insurer or other credit provider could affect the value of the security and the Fund’s share price. Not all securities are rated. In the event that rating agencies assign different ratings to the same security, the Fund’s investment manager will determine which rating it believes best reflects the security’s quality and risk at that time. Credit risks associated with certain particular classifications of municipal securities include:General Obligation Bonds-Timely payments depend on the issuer’s credit quality, ability to raise tax revenues, and ability to maintain an adequate tax base.Revenue Bonds-Payments depend on the money earned by the particular facility or class of facilities, or the amount of revenues derived from another source.Private Activity Bonds-Municipalities and other public authorities issue private activity bonds to finance development of facilities for use by a private enterprise. The private enterprise pays the principal and interest on the bond, and the issuer does not pledge its full faith, credit, and taxing power for repayment. | ||||
| Nebraska Municipal Fund | Municipal insurance risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Municipal insurance risk. The Fund’s investments may include investments in insured municipal securities. Municipal security insurance does not guarantee the value of either individual municipal securities or of shares of the Fund. In addition, a municipal security insurance policy generally will not cover: (i) repayment of a municipal security before maturity (redemption), (ii) prepayment or payment of an acceleration premium (except for a mandatory sinking fund redemption) or any other provision of a bond indenture that advances the maturity of the bond or (iii) nonpayment of principal or interest caused by negligence or bankruptcy of the paying agent. A mandatory sinking fund redemption may be a provision of a municipal security issue whereby part of the municipal security issue may be retired before maturity. Downgrades and withdrawal of ratings from insurers of municipal securities have substantially limited the availability of insurance sought by issuers of municipal securities thereby reducing the supply of insured municipal securities. Because of the consolidation among insurers of municipal securities, to the extent that the Fund invests in insured municipal securities, it is subject to the risk that credit risk may be concentrated among fewer insurers and the risk that events involving one or more insurers could have a significant adverse effect on the value of the securities insured by an insurer and on the municipal markets as a whole. | ||||
| Nebraska Municipal Fund | Call risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Call risk. Call risk is the likelihood that a security will be prepaid (or “called”) before maturity. An issuer is more likely to call its bonds when interest rates are falling, because the issuer can issue new bonds with lower interest payments. If a bond is called, the Fund may have to replace it with a lower-yielding security. | ||||
| Nebraska Municipal Fund | Extension risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Extension risk. Extension risk is the risk that an issuer will exercise its right to pay principal on an obligation held by the Fund later than expected. This may happen during a period of rising interest rates. Under these circumstances, the value of the obligation will decrease and the Fund will suffer from the inability to invest in higher yielding securities. | ||||
| Nebraska Municipal Fund | Portfolio strategy risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Portfolio strategy risk. The investment manager’s skill in choosing appropriate investments for the Fund will determine in part the Fund’s ability to achieve its investment objective. | ||||
| Nebraska Municipal Fund | Inflation risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Inflation risk. There is a possibility that the rising prices of goods and services may have the effect of offsetting a Fund’s real return. This is likely to have a greater impact on the returns of bond funds and money market funds, which historically have had more modest returns in comparison to equity funds. As inflation increases, the value of the Fund’s assets can decline as can the value of the Fund’s distributions. | ||||
| Nebraska Municipal Fund | Tax risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Tax risk. Income from municipal securities held by the Fund could be declared taxable because of unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service or state tax authorities, or noncompliant conduct of a bond issuer. Moreover, a portion of the Fund’s otherwise exempt-interest dividends may be taxable to those shareholders subject to the federal alternative minimum tax. In addition, proposals have been made to restrict or eliminate the federal income tax exemption for interest on municipal securities, and similar proposals may be introduced in the future. Proposed “flat tax” and “value added tax” proposals could also have the effect of eliminating the tax preference for municipal securities. Some of these proposals would apply to interest on municipal securities issued before the date of enactment, which would adversely affect their value to a material degree. If such a proposal were enacted, the availability of municipal securities for investment by the Fund and the value of the Fund’s portfolio would be adversely affected. | ||||
| Nebraska Municipal Fund | Municipal sector risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Municipal sector risk. The Fund may invest more than 25% of its total assets in municipal securities that finance, or pay interest from the revenues of, similar projects that tend to be impacted the same or similar ways by economic, business, or political developments, which would increase credit risk. For example, legislation on the financing of a project or a declining economic need for the project would likely affect all similar projects. | ||||
| Nebraska Municipal Fund | Risks of health care revenue bonds [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Risks of health care revenue bonds. The Fund may invest in health care revenue bonds. The health care sector is subject to regulatory action by a number of private and governmental agencies, including federal, state, and local governmental agencies. A major source of revenues for the health care sector is payments from the Medicare and Medicaid programs. As a result, the sector is sensitive to legislative changes and reductions in governmental spending for such programs. Numerous other factors may affect the sector, such as general economic conditions; demand for services; expenses (including malpractice insurance premiums); and competition among health care providers. In addition, various factors may adversely affect health care facility operations, including adoption of national, state and/or local health care reform measures; medical and technological advances which dramatically alter the need for health services or the way in which such services are delivered; changes in medical coverage which alter the traditional fee-for-service revenue stream; and efforts by employers, insurers and governmental agencies to reduce the costs of health care insurance and health care services. | ||||
| Nebraska Municipal Fund | Risks of housing revenue bonds [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Risks of housing revenue bonds. The Fund may invest in housing revenue bonds. Housing revenue bonds are generally issued by a state, county, city, local housing authority, or other public agency. They generally are secured by the revenues derived from mortgages purchased with the proceeds of the bond issue. It is extremely difficult to predict the supply of available mortgages to be purchased with the proceeds of an issue or the future cash flow from the underlying mortgages. Consequently, there are risks that proceeds will exceed supply, resulting in early retirement of bonds, or that homeowner repayments will create an irregular cash flow. Many factors may affect the financing of multi-family housing projects, including acceptable completion of construction, proper management, occupancy and rent levels, economic conditions, and changes to current laws and regulations. | ||||
| Nebraska Municipal Fund | Risks of transportation revenue bonds [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Risks of transportation revenue bonds. The Fund may invest in transportation revenue bonds. Transportation debt may be issued to finance the construction of airports, toll roads, highways, or other transit facilities. Airport bonds are dependent on the general stability of the airline industry and on the stability of a specific carrier who uses the airport as a hub. Air traffic generally follows broader economic trends and is also affected by the price and availability of fuel. Toll road bonds are also affected by the cost and availability of fuel as well as toll levels, the presence of competing roads and the general economic health of an area. Fuel costs and availability also affect other transportation-related securities, as does the presence of alternate forms of transportation, such as public transportation. | ||||
| Nebraska Municipal Fund | Risks of educational revenue bonds [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Risks of educational revenue bonds. The Fund may invest in educational revenue bonds. These include municipal securities that are obligations of issuers which are, or which govern the operation of, schools, colleges, and universities and whose revenues are derived mainly from ad valorem taxes, or for higher education systems, from tuition, dormitory revenues, grants, and endowments. Litigation or legislation pertaining to ad valorem taxes may affect sources of funds available for the payment of school bonds. College and university obligations may be affected by the possible inability to raise tuitions and fees sufficiently to cover increased operating costs, the uncertainty of continued receipt of Federal grants and state funding, and new government or legislation or regulations which may adversely affect the revenues or costs of such issuers. In addition, student loan revenue bonds, which are generally offered by state (or sub-state) authorities or commissions and backed by pools of student loans, may be affected by numerous factors, including the rate of student loan defaults, seasoning of the loan portfolio, student repayment deferral periods of forbearance, potential changes in federal legislation, and state guarantee agency reimbursement. | ||||
| Nebraska Municipal Fund | Risks of electric utility revenue bonds [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Risks of electric utility revenue bonds. The Fund may invest in electric utility revenue bonds. The electric utilities industry has been experiencing increased competitive pressures. Additional risks associated with electric utility revenue bonds include: (a) the availability and costs of fuel; (b) the availability and costs of capital; (c) the effects of conservation on energy demand; (d) the effects of rapidly changing environmental, safety, and licensing requirements, and other federal, state and local regulations; (e) timely and sufficient rate increases; and (f) opposition to nuclear power. | ||||
| Nebraska Municipal Fund | Risks of gas utility revenue bonds [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Risks of gas utility revenue bonds. The Fund may invest in gas utility revenue bonds. Gas utilities are subject to the risks of supply conditions and increased competition from other providers of utility services. In addition, gas utilities are affected by gas prices, which may be magnified to the extent that a gas company enters into long-term contracts for the purchase or sale of gas at fixed prices, since such prices may change significantly and to the disadvantage of the gas utility in the open market. Gas utilities are particularly susceptible to supply and demand imbalances due to unpredictable climate conditions and other factors and are subject to regulatory risks as well. | ||||
| Nebraska Municipal Fund | Risks of water and sewer revenue bonds [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Risks of water and sewer revenue bonds. The Fund may invest in water and sewer revenue bonds. Issuers of water and sewer bonds face public resistance to rate increases, costly environmental litigation and Federal environmental mandates. In addition, the lack of water supply due to insufficient rain, run-off, or snow pack may be a concern. | ||||
| Nebraska Municipal Fund | Cybersecurity risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Cybersecurity risk. Cybersecurity breaches may allow an unauthorized party to gain access to Fund assets, customer data, or proprietary information, or cause the Fund and/or its service providers to suffer data corruption or lose operational functionality. The Fund’s share price may decline as a result of unauthorized actions taken during a security breach or subsequent market activity in response to the security breach. | ||||
| Nebraska Municipal Fund | Valuation risk [Member] | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Risk [Text Block] | rr_RiskTextBlock | Valuation risk. The sales price the Fund could receive for any particular portfolio investment may differ from the Fund’s valuation of the investment, particularly for securities that trade in thin or volatile markets or that are valued using a fair value methodology. | ||||
| Nebraska Municipal Fund | Bloomberg U.S. Municipal Bond Index(1) (reflects no deduction for fees, expenses, or taxes) | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Index No Deduction for Fees, Expenses, Taxes [Text] | rr_IndexNoDeductionForFeesExpensesTaxes | reflects no deduction for fees, expenses, or taxes | ||||
| Label | rr_AverageAnnualReturnLabel | Bloomberg U.S. Municipal Bond Index(1) (reflects no deduction for fees, expenses, or taxes) | ||||
| 1 Year | rr_AverageAnnualReturnYear01 | 6.40% | [1] | |||
| 5 Years | rr_AverageAnnualReturnYear05 | 2.25% | [1] | |||
| 10 Years | rr_AverageAnnualReturnYear10 | 3.03% | [1] | |||
| Since Inception | rr_AverageAnnualReturnSinceInception | 2.12% | [1] | |||
| Nebraska Municipal Fund | Class A | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | 2.50% | ||||
| Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of purchase price or redemption proceeds) | rr_MaximumDeferredSalesChargeOverOfferingPrice | 1.00% | ||||
| Maximum Sales Charge (Load) Imposed on Reinvested Dividends | rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther | none | ||||
| Redemption Fee Imposed (as a percentage of amount redeemed, if applicable) | rr_RedemptionFeeOverRedemption | none | ||||
| Exchange Fee | rr_ExchangeFee | none | ||||
| Management Fees | rr_ManagementFeesOverAssets | 0.50% | ||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 0.25% | ||||
| Other Expenses | rr_OtherExpensesOverAssets | 0.49% | ||||
| Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 1.24% | ||||
| Fee Waivers and Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.26%) | [2] | |||
| Total Annual Fund Operating Expenses After Fee Waivers and Expense Reimbursements | rr_NetExpensesOverAssets | 0.98% | [2] | |||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 347 | ||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 609 | ||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 890 | ||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | $ 1,690 | ||||
| Annual Return 2014 | rr_AnnualReturn2014 | 8.48% | ||||
| Annual Return 2015 | rr_AnnualReturn2015 | 3.03% | ||||
| Annual Return 2016 | rr_AnnualReturn2016 | (0.59%) | ||||
| Annual Return 2017 | rr_AnnualReturn2017 | 4.32% | ||||
| Annual Return 2018 | rr_AnnualReturn2018 | 0.49% | ||||
| Annual Return 2019 | rr_AnnualReturn2019 | 5.21% | ||||
| Annual Return 2020 | rr_AnnualReturn2020 | 3.22% | ||||
| Annual Return 2021 | rr_AnnualReturn2021 | (0.26%) | ||||
| Annual Return 2022 | rr_AnnualReturn2022 | (9.03%) | ||||
| Annual Return 2023 | rr_AnnualReturn2023 | 4.17% | ||||
| Year to Date Return, Label | rr_YearToDateReturnLabel | year-to-date | ||||
| Bar Chart, Year to Date Return, Date | rr_BarChartYearToDateReturnDate | Sep. 30, 2024 | ||||
| Bar Chart, Year to Date Return | rr_BarChartYearToDateReturn | 0.96% | ||||
| Highest Quarterly Return, Label | rr_HighestQuarterlyReturnLabel | highest return | ||||
| Highest Quarterly Return, Date | rr_BarChartHighestQuarterlyReturnDate | Dec. 31, 2023 | ||||
| Highest Quarterly Return | rr_BarChartHighestQuarterlyReturn | 6.82% | ||||
| Lowest Quarterly Return, Label | rr_LowestQuarterlyReturnLabel | lowest return | ||||
| Lowest Quarterly Return, Date | rr_BarChartLowestQuarterlyReturnDate | Mar. 31, 2022 | ||||
| Lowest Quarterly Return | rr_BarChartLowestQuarterlyReturn | (5.08%) | ||||
| Label | rr_AverageAnnualReturnLabel | Return Before Taxes | ||||
| 1 Year | rr_AverageAnnualReturnYear01 | 1.59% | ||||
| 5 Years | rr_AverageAnnualReturnYear05 | 0.02% | ||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.54% | ||||
| Since Inception | rr_AverageAnnualReturnSinceInception | |||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Nov. 17, 1993 | ||||
| Nebraska Municipal Fund | Class A | Return After Taxes on Distributions | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Label | rr_AverageAnnualReturnLabel | Return After Taxes on Distributions | ||||
| 1 Year | rr_AverageAnnualReturnYear01 | 1.59% | ||||
| 5 Years | rr_AverageAnnualReturnYear05 | 0.02% | ||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.54% | ||||
| Since Inception | rr_AverageAnnualReturnSinceInception | |||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Nov. 17, 1993 | ||||
| Nebraska Municipal Fund | Class A | Return After Taxes on Distributions and Sale of Fund Shares | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Label | rr_AverageAnnualReturnLabel | Return After Taxes on Distributions and Sale of Fund Shares | ||||
| 1 Year | rr_AverageAnnualReturnYear01 | 1.86% | ||||
| 5 Years | rr_AverageAnnualReturnYear05 | 0.46% | ||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.71% | ||||
| Since Inception | rr_AverageAnnualReturnSinceInception | |||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Nov. 17, 1993 | ||||
| Nebraska Municipal Fund | Class I | ||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||
| Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||
| Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of purchase price or redemption proceeds) | rr_MaximumDeferredSalesChargeOverOfferingPrice | none | ||||
| Maximum Sales Charge (Load) Imposed on Reinvested Dividends | rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther | none | ||||
| Redemption Fee Imposed (as a percentage of amount redeemed, if applicable) | rr_RedemptionFeeOverRedemption | none | ||||
| Exchange Fee | rr_ExchangeFee | none | ||||
| Management Fees | rr_ManagementFeesOverAssets | 0.50% | ||||
| Distribution and Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||
| Other Expenses | rr_OtherExpensesOverAssets | 0.49% | ||||
| Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 0.99% | ||||
| Fee Waivers and Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.26%) | [2] | |||
| Total Annual Fund Operating Expenses After Fee Waivers and Expense Reimbursements | rr_NetExpensesOverAssets | 0.73% | [2] | |||
| Expense Example, with Redemption, 1 Year | rr_ExpenseExampleYear01 | $ 75 | ||||
| Expense Example, with Redemption, 3 Years | rr_ExpenseExampleYear03 | 289 | ||||
| Expense Example, with Redemption, 5 Years | rr_ExpenseExampleYear05 | 522 | ||||
| Expense Example, with Redemption, 10 Years | rr_ExpenseExampleYear10 | $ 1,189 | ||||
| Label | rr_AverageAnnualReturnLabel | Return Before Taxes | ||||
| 1 Year | rr_AverageAnnualReturnYear01 | 4.54% | ||||
| 5 Years | rr_AverageAnnualReturnYear05 | 0.79% | ||||
| 10 Years | rr_AverageAnnualReturnYear10 | |||||
| Since Inception | rr_AverageAnnualReturnSinceInception | 0.91% | ||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Nov. 01, 2017 | ||||
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