v3.22.4
Label Element Value
Class I | NICHOLAS II INC  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading SUMMARY
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The Fund strives to increase the value of your investment over the long-term (“long-term growth”).
Expense [Heading] rr_ExpenseHeading Fees and Expenses of the Fund
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock The table below describes the fees and expenses that you may pay if you buy and hold 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.
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 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 in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 15.76% of the average value of the portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 15.76%
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.The Example assumes that you invest $10,000 inthe Fund for the time periods indicated and thenredeem all of your shares at the end of thoseperiods. The Example also assumes that yourinvestment has a 5% return each year and thatthe Fund’s operating expenses remain the same.Although your actual costs may be higher orlower, based on these assumptions, your costswould be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
     To pursue the Fund’s investment objective of long-term growth, it primarily invests in common stocks of domestic corporations with medium-sized market capitalizations believed to have growth potential. The Fund believes a company’s annual sales volume and the market capitalization (the number of shares outstanding multiplied by the per share price) are the factors most illustrative of a company’s size. In distinguishing company size in terms of sales volume, the Fund considers a company’s sales volume relative to peer companies in the company’s industry. In terms of market 
capitalization, the Fund generally considers companies with market capitalizations up to $3 billion as “small,” between $3 billion and $25 billion as “medium,” and greater than $25 billion as “large.” To a lesser extent, the Fund may invest in companies with small and large market capitalizations. The Fund looks for established companies with the potential for superior growth in sales and earnings in a diversified group of industries. The Fund’s investment philosophy is basically a long-term growth philosophy, based upon the assumption that if a company achieves superior growth in sales and earnings, eventually the company’s stock will achieve superior performance. It is anticipated that a major portion of the Fund’s portfolio will be invested in common stocks of the types of companies, and in the manner, as described above. 
Risk [Heading] rr_RiskHeading Principal Risks of Investing
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
     As with any mutual fund, the Fund cannot guarantee that it will achieve its goals or that its performance will be positive over any period of time. The Fund’s investments change in value. Consequently, the value of your Fund shares may change. If the value of the Fund shares or the values of the Fund’s investments go down, you may lose money.
The principal risks of investing in the Fund are: 
Market Risk – Market risk involves the possibility that the value of the Fund’s investments will fluctuate as the stock market fluctuates over short- or longer-term periods. Common stocks prices tend to be more volatile than other investments choices.
Portfolio-Specific Risk – From time to time, the value of an individual company may decline due to a particular set of circumstances affecting that company, its industry or certain companies within the industry, while having little or no impact on other similar companies within the industry. Because the Fund will invest most of its assets in the securities of mid-cap companies and to a lesser extent, small-cap companies, the Fund may face additional risks. Small- to mid- cap companies often have a limited market for their securities and limited financial resources, and are usually more affected by changes in the economy. Securities of small to medium capitalization companies also often fluctuate in price more than common stocks of larger capitalization companies.
Selection Risk – The Fund also faces selection risk, which is the risk that the stocks the Fund purchases will underperform markets or other mutual funds with similar investment objectives and strategies.
Public Health Threats Risk – Threats to public health can have a negative impact on the global economy and financial markets, which could adversely affect the securities held by the Fund.
Impacts of public health threats may last for an extended period of time and result in a substantial economic downturn. Health crises caused by outbreaks, such as the coronavirus (COVID-19) outbreak, may exacerbate other pre-existing political, social and economic risks and disrupt normal market conditions and operations. The impact of this outbreak, and other epidemics and pandemics that may arise in the future, could negatively affect the worldwide economy, as well as the economies of individual countries, individual companies and the market in general in significant and unforeseen ways. These developments as well as other events could result in further market volatility and negatively affect security prices, the liquidity of certain securities and the normal operations of securities exchanges and other markets. As a result, the risk environment remains elevated. The Adviser will monitor developments and seek to manage the Fund in a manner consistent with achieving the Fund’s investment objective, but there can be no assurance that it will be successful in doing so.
Cybersecurity Risk – The Fund, its service providers, and third party fund distribution platforms, and your ability to transact with the Fund, may be negatively impacted due to operational risks arising from, among other issues, human errors, systems and technology disruptions or failures, or cybersecurity incidents. Cybersecurity incidents may allow an unauthorized party to gain access to fund assets, customer data, or proprietary information, or cause the Fund or its service providers, as well as the securities trading venues and their service providers, to suffer data corruption or lose
operational functionality. The occurrence of any of these issues could result in a loss of information, regulatory scrutiny, reputational damage and other consequences, any of which could have a material adverse effect on the Fund or its shareholders. Cybersecurity incidents could also affect issuers of securities in which the Fund invests, leading to significant loss of value. 
     Since there are risks inherent in all investments in securities, there is no assurance that the Fund’s objectives will be achieved. 
Risk Lose Money [Text] rr_RiskLoseMoney If the value of the Fund shares or the values of the Fund’s investments go down, you may lose money.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
     The bar chart shown below provides some indication of the risks of investing in the Fund. The chart shows the variability of the Fund’s total return for the last ten calendar years(1). Updated performance information for the Fund is available on our website at www.nicholasfunds.com.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The bar chart shown below provides some indication of the risks of investing in the Fund. The chart shows the variability of the Fund’s total return for the last ten calendar years(1).
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.nicholasfunds.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Of course, the Fund’s past performance (before and after taxes) is no guarantee of its future returns.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
     For the ten calendar year periods shown in the above bar chart, the highest quarterly return was 24.01% (for the quarter ended June 30, 2020) and the lowest quarterly return was -23.35% (for the quarter ended March 31, 2020).
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 Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock
     This next table shows how the Fund’s average annual total returns for the one, five and ten year periods ending on December 31, 2022 (the Fund’s most recently completed calendar year), compared to the returns of broad measures of market performance and the performance average of similar mutual funds. The table also shows the Fund’s average annual total returns after taxes on distributions and after taxes on distributions and the redemption of all of your Fund shares. 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. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
     Of course, the Fund’s past performance (before and after taxes) is no guarantee of its future returns.
Class I | NICHOLAS II INC | Class I  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) rr_MaximumDeferredSalesChargeOverOther none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther none
Wire Redemption Fee rr_RedemptionFee $ 15.00
Exchange Fee rr_ExchangeFeeOverRedemption none
Management Fees rr_ManagementFeesOverAssets 0.52%
Distribution (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.59%
One Year rr_ExpenseExampleYear01 $ 60
Three Years rr_ExpenseExampleYear03 189
Five Years rr_ExpenseExampleYear05 329
Ten Years rr_ExpenseExampleYear10 $ 738
2013 rr_AnnualReturn2013 32.74% [1]
2014 rr_AnnualReturn2014 11.27% [1]
2015 rr_AnnualReturn2015 0.92% [1]
2016 rr_AnnualReturn2016 4.87% [1]
2017 rr_AnnualReturn2017 25.63% [1]
2018 rr_AnnualReturn2018 (4.74%) [1]
2019 rr_AnnualReturn2019 34.88% [1]
2020 rr_AnnualReturn2020 15.72% [1]
2021 rr_AnnualReturn2021 21.58% [1]
2022 rr_AnnualReturn2022 (18.00%) [1]
Year to Date Return, Label rr_YearToDateReturnLabel year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Dec. 31, 2022
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn (18.00%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel highest quarterly return
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 24.01%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel lowest quarterly return
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (23.35%)
One Year rr_AverageAnnualReturnYear01 (18.00%)
Five Year rr_AverageAnnualReturnYear05 8.19%
Ten Year rr_AverageAnnualReturnYear10 11.28%
Class I | NICHOLAS II INC | Return After Taxes on Distributions | Class I  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 (18.78%)
Five Year rr_AverageAnnualReturnYear05 6.22%
Ten Year rr_AverageAnnualReturnYear10 9.18%
Class I | NICHOLAS II INC | Return After Taxes on Distributions and Sale of Fund Shares | Class I  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 (10.17%)
Five Year rr_AverageAnnualReturnYear05 6.30%
Ten Year rr_AverageAnnualReturnYear10 8.88%
Class I | NICHOLAS II INC | Russell Midcap Growth Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 (26.72%)
Five Year rr_AverageAnnualReturnYear05 7.64%
Ten Year rr_AverageAnnualReturnYear10 11.41%
Class I | NICHOLAS II INC | Russell Midcap Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 (17.32%)
Five Year rr_AverageAnnualReturnYear05 7.10%
Ten Year rr_AverageAnnualReturnYear10 10.96%
Class I | NICHOLAS II INC | Morningstar Mid-Cap Growth Category (reflects no deduction for taxes)  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 (27.79%)
Five Year rr_AverageAnnualReturnYear05 7.09%
Ten Year rr_AverageAnnualReturnYear10 10.67%
[1] The Fund’s fiscal year end is September 30. As reflected in the bar chart, the Fund’s year-to-date return as of December 31, 2022 was -18.00%.