Label	Element	Value
Mid Cap Stock Portfolio
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks capital appreciation through investments, primarily in equity securities, which are believed to be undervalued in the marketplace.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES
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 table and examples below. The table does not reflect the fees and expenses of variable annuity contracts or variable life insurance policies (together, “Variable Contracts”). If such fees and expenses were reflected, expenses shown would be higher.
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. These costs, which are not reflected in the annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 52% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	52.00%
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 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 and that the Fund’s operating expenses remain the same. The Example does not reflect Variable Contract expenses, fees, and charges. If these expenses, fees, and charges were included, your costs would be higher. Although your actual costs 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	Under normal conditions, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in equity securities of mid-sized companies. A mid-sized company is defined as a company having a market capitalization at the time of purchase that falls within the market capitalization range of companies in the Russell Midcap^® Index. The Fund seeks to invest in securities of companies that the portfolio management team believes are undervalued by the market and are selling at reasonable prices in relation to the portfolio management team’s assessment of their potential or intrinsic value. Equity securities in which the Fund may invest include common stocks, preferred stocks, equity interests in trusts (including real estate investment trusts (“REITs”) and privately offered trusts), partnerships, joint ventures, limited liability companies and vehicles with similar legal structures, other instruments convertible or exercisable into the foregoing, and other investments with similar economic characteristics. The Fund may invest up to 20% of its net assets in securities of foreign companies, including emerging market companies, American Depositary Receipts (“ADRs”), Global Depositary Receipts (“GDRs”), and other similar depositary receipts. In addition to ADRs, the Fund generally defines foreign companies as those whose securities are traded primarily on non-U.S. securities exchanges. The investment team may also consider the risks and return potential presented by environmental, social, and governance (“ESG”) factors in investment decisions. The Fund may sell a security when the Fund believes the security is less likely to benefit from the current market and economic environment, or shows signs of deteriorating fundamentals, among other reasons. The Fund may deviate from the investment strategy described above for temporary defensive purposes. The Fund may miss certain investment opportunities if defensive strategies are used and thus may not achieve its investment objective.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table below provide some indication of the risks of investing in the Fund by illustrating the variability of the Fund’s returns. Each assumes reinvestment of dividends and distributions. The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table below provide some indication of the risks of investing in the Fund by illustrating the variability of the Fund’s returns.
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Bar Chart (per calendar year) - Class VC Shares
Bar Chart Narrative [Text Block]	rr_BarChartNarrativeTextBlock	The bar chart shows changes in the performance of the Fund’s Class VC shares from calendar year to calendar year. This chart does not reflect the sales charges or other expenses of Variable Contracts. If those sales charges and expenses were reflected, returns would be lower.
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	This chart does not reflect the sales charges or other expenses of Variable Contracts. If those sales charges and expenses were reflected, returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter 4th Q 2020 +22.82% Worst Quarter 1st Q 2020 -30.54%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2024)
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The table below shows how the Fund’s average annual total returns compare to the returns of securities market indices with investment characteristics similar to those of the Fund as well as to a broad-based securities market index.¹ ¹ The Fund has adopted the S&P 500^® Index as its broad-based securities market index.
Mid Cap Stock Portfolio \| PRINCIPAL RISKS
Risk/Return:	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	PRINCIPAL RISKS As with any investment in a mutual fund, investing in the Fund involves risk, including the risk that you may receive little or no return on your investment. When you redeem your shares, they may be worth more or less than what you paid for them, which means that you may lose a portion or all of the money you invested in the Fund. The principal risks of investing in the Fund, which could adversely affect its performance, include:
Mid Cap Stock Portfolio \| Risk Lose Money [Member]
Risk/Return:	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	As with any investment in a mutual fund, investing in the Fund involves risk, including the risk that you may receive little or no return on your investment. When you redeem your shares, they may be worth more or less than what you paid for them, which means that you may lose a portion or all of the money you invested in the Fund.
Mid Cap Stock Portfolio \| Risk Not Insured [Member]
Risk/Return:	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Mid Cap Stock Portfolio \| · Portfolio Management Risk
Risk/Return:	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	· Portfolio Management Risk: If the strategies used and investments selected by the Fund’s portfolio management team fail to produce the intended result, the Fund may suffer losses or underperform other funds with the same investment objective or strategies, even in a favorable market.
Mid Cap Stock Portfolio \| · Market Risk
Risk/Return:	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	· Market Risk: The market values of securities will fluctuate, sometimes sharply and unpredictably, based on overall economic conditions, governmental actions or intervention, market disruptions caused by trade disputes, tariffs or other factors, political developments, and other factors. Prices of equity securities tend to rise and fall more dramatically than those of debt securities.
Mid Cap Stock Portfolio \| · Equity Securities Risk
Risk/Return:	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	· Equity Securities Risk: Equity securities, as well as equity-like securities such as convertible debt securities, may experience significant volatility. Such securities may fall sharply in response to adverse events affecting overall markets, a particular industry or sector, or an individual company’s financial condition.
Mid Cap Stock Portfolio \| · Industry and Sector Risk
Risk/Return:	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	· Industry and Sector Risk: Although the Fund does not employ an industry or sector focus, its exposure to specific industries or sectors will increase from time to time based on the portfolio management team’s perception of investment opportunities. If the Fund is overweight in a single industry or sector relative to its benchmark index, the Fund will face an increased risk that the value of its portfolio will decrease because of events disproportionately affecting that industry or sector. Furthermore, investments in particular industries or sectors may be more volatile than the broader market as a whole.
Mid Cap Stock Portfolio \| · Mid-Sized Company Risk
Risk/Return:	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	· Mid-Sized Company Risk: Investments in mid-sized companies may involve greater risks than investments in larger, more established companies. Securities of mid-sized companies tend to be more sensitive to changing economic, market, and industry conditions and tend to be more volatile and less liquid than equity securities of larger companies, especially over the short term. The securities of mid-sized companies tend to trade less frequently than those of larger, more established companies, which can adversely affect the pricing of these securities and the ability to sell these securities in the future.
Mid Cap Stock Portfolio \| · Value Investing Risk
Risk/Return:	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	· Value Investing Risk: The prices of value stocks may lag the stock market for long periods of time if the market fails to recognize the company’s intrinsic worth. Value investing also is subject to the risk that a company judged to be undervalued may actually be appropriately priced or even overpriced.
Mid Cap Stock Portfolio \| · Foreign and Emerging Market Company Risk
Risk/Return:	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	· Foreign and Emerging Market Company Risk: Investments in foreign companies and in U.S. companies with economic ties to foreign markets generally involve special risks. These companies may be more vulnerable to economic, political, and social instability and subject to less government supervision, lack of transparency, inadequate regulatory and accounting standards, and foreign taxes. Foreign company securities also include ADRs, which may be less liquid than the underlying shares in their primary trading market. Foreign securities also may subject the Fund’s investments to changes in currency exchange rates. Emerging market securities generally are more volatile than other foreign securities, and are subject to greater liquidity, regulatory, and political risks. Investments in emerging markets may be considered speculative and generally are riskier than investments in more developed markets. Emerging markets are more likely to experience hyperinflation and currency devaluations. Securities of emerging market companies may have far lower trading volumes and less liquidity than securities of issuers in developed markets. In certain emerging market countries, governments participate to a significant degree in their respective economies. Action by these governments could have a significant adverse effect on market prices of securities and payment of dividends. Companies with economic ties to emerging markets may be susceptible to the same risks as companies organized in emerging markets.
Mid Cap Stock Portfolio \| · Real Estate Risk
Risk/Return:	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	· Real Estate Risk: An investment in a REIT generally is subject to the risks that impact the value of the underlying properties or mortgages of the REIT. These risks include loss to casualty or condemnation, and changes in supply and demand, interest rates, zoning laws, regulatory limitations on rents, property taxes, and operating expenses. Other factors that may adversely affect REITs include poor performance by management of the REIT, changes to the tax laws, or failure by the REIT to qualify for favorable tax treatment under the Internal Revenue Code of 1986, as amended (the “Code”), and changes in local, regional, or general economic conditions.
Mid Cap Stock Portfolio \| · Liquidity/Redemption Risk
Risk/Return:	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	· Liquidity/Redemption Risk: The Fund may lose money when selling securities at inopportune times to fulfill shareholder redemption requests. The risk of loss may increase depending on the size and frequency of redemption requests, whether the redemption requests occur in times of overall market turmoil or declining prices, and whether the securities the Fund intends to sell have decreased in value or are illiquid. The Fund may be less able to sell illiquid securities at its desired time or price. It may be more difficult for the Fund to value its investments in illiquid securities than more liquid securities.
Mid Cap Stock Portfolio \| Russell Midcap® Value Index
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	Russell Midcap® Value Index
1 Year	rr_AverageAnnualReturnYear01	13.07%
5 Years	rr_AverageAnnualReturnYear05	8.59%
10 Years	rr_AverageAnnualReturnYear10	8.10%
Mid Cap Stock Portfolio \| S&P MidCap 400® Value Index
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	S&P MidCap 400® Value Index
1 Year	rr_AverageAnnualReturnYear01	11.71%
5 Years	rr_AverageAnnualReturnYear05	10.21%
10 Years	rr_AverageAnnualReturnYear10	9.13%
Mid Cap Stock Portfolio \| S&P 500® Index
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	S&P 500® Index
1 Year	rr_AverageAnnualReturnYear01	25.02%
5 Years	rr_AverageAnnualReturnYear05	14.53%
10 Years	rr_AverageAnnualReturnYear10	13.10%
Mid Cap Stock Portfolio \| VC Shares
Risk/Return:	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.73%
Other Expenses	rr_OtherExpensesOverAssets	0.41%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.14%
1 Year	rr_ExpenseExampleYear01	$ 116
3 Years	rr_ExpenseExampleYear03	362
5 Years	rr_ExpenseExampleYear05	628
10 Years	rr_ExpenseExampleYear10	$ 1,386
Annual Return 2015	rr_AnnualReturn2015	(3.79%)
Annual Return 2016	rr_AnnualReturn2016	16.39%
Annual Return 2017	rr_AnnualReturn2017	6.83%
Annual Return 2018	rr_AnnualReturn2018	(15.04%)
Annual Return 2019	rr_AnnualReturn2019	22.64%
Annual Return 2020	rr_AnnualReturn2020	2.50%
Annual Return 2021	rr_AnnualReturn2021	28.70%
Annual Return 2022	rr_AnnualReturn2022	(11.21%)
Annual Return 2023	rr_AnnualReturn2023	15.42%
Annual Return 2024	rr_AnnualReturn2024	14.90%
Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2020
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	22.82%
Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2020
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(30.54%)
1 Year	rr_AverageAnnualReturnYear01	14.90%
5 Years	rr_AverageAnnualReturnYear05	9.21%
10 Years	rr_AverageAnnualReturnYear10	6.83%

If the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form N-1A
-Section 4
-Subsection b
-Paragraph 2
-Subparagraph ii