Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Apr. 30, 2012
Bond Market Index Account (Prospectus Summary) | Bond Market Index Account
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Bond Market Index Account
Investment Objective, Heading	rr_ObjectiveHeading	Objective:
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Account seeks to provide current income.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Account
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Account. These fees and expenses do not reflect the fees and expenses of any variable insurance contract that may invest in the Account and would be higher if they did.
Operating Expenses, Caption	rr_OperatingExpensesCaption	Annual Account 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	rr_PortfolioTurnoverTextBlock	The Account 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 annual Account operating expenses or in the example, affect the Account's performance. This is a new Account and does not yet have a portfolio turnover rate to disclose.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	Other expenses estimated for the year ending December 31, 2012.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Account with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Account 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 Account's operating expenses remain the same. If separate account expenses and contract level expenses were included, expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal circumstances, the Account invests at least 80% of its net assets in debt securities held by the Barclays Capital U.S. Aggregate Bond Index (the "Index") at the time of purchase. The Index is composed of investment grade, fixed rate debt issues, including government, corporate, asset-backed, and mortgage-backed securities, with maturities of one year or more. The Account employs a passive investment approach designed to attempt to track the performance of the Index. The Account may actively trade portfolio securities. Under normal circumstances, the Account maintains an average portfolio duration that is in line with the duration of the Barclays Capital U.S. Aggregate Bond Index, which as of December 31, 2011 was 5.01 years.
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	The Account may be an appropriate investment for investors interested in investing in a fixed-income mutual fund and preferring a passive, rather than active, management style. The value of your investment in the Account changes with the value of the Account's investments. Many factors affect that value, and it is possible to lose money by investing in the Account. An investment in the Account is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks of investing in the Account, in alphabetical order, are: Active Trading Risk. Actively trading portfolio securities may accelerate realization of taxable gains and losses, lower fund performance and may result in high portfolio turnover rates and increased brokerage costs.    Fixed-Income Securities Risk. Fixed-income securities are subject to interest rate risk and credit quality risk. The market value of fixed-income securities generally declines when interest rates rise, and an issuer of fixed-income securities could default on its payment obligations. Index Fund Investment Risk. More likely than not, an index fund will not provide investment performance that matches the index performance due to cashflows and the fees and expenses of the fund. Portfolio Duration Risk. Portfolio duration is a measure of the expected life of a fixed-income security and its sensitivity to changes in interest rates. The longer a fund's average portfolio duration, the more sensitive the fund will be to changes in interest rates. Prepayment Risk. Unscheduled prepayments on mortgage-backed and asset-backed securities may have to be reinvested at lower rates. A reduction in prepayments may increase the effective maturities of these securities, exposing them to the risk of decline in market value over time (extension risk). Real Estate Securities Risk. Real estate securities are subject to the risks associated with direct ownership of real estate, including declines in value, adverse economic conditions, increases in expenses, regulatory changes and environmental problems. Risk of Being an Underlying Fund. An underlying fund of a fund of funds may experience relatively large redemptions or investments as the fund of funds periodically reallocates or rebalances its assets. These transactions may cause the underlying fund to sell portfolio securities to meet such redemptions, or to invest cash from such investments, at times it would not otherwise do so, and may as a result increase transaction costs and adversely affect underlying fund performance. U.S. Government Securities Risk. Yields available from U.S. government securities are generally lower than yields from many other fixed-income securities. U.S. Government Sponsored Securities Risk. Securities issued by U.S. government-sponsored or -chartered enterprises such as the Federal Home Loan Mortgage Corporation, the Federal National Mortgage Association, and the Federal Home Loan Banks are not issued or guaranteed by the U.S. Treasury.
Risk, Lose Money	rr_RiskLoseMoney	Many factors affect that value, and it is possible to lose money by investing in the Account.
Risk, Not Insured Depository Institution	rr_RiskNotInsuredDepositoryInstitution	An investment in the Account is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	No performance is shown because the Account has not yet had a calendar year of performance. The Account's performance will be benchmarked against the Barclays Capital U.S. Aggregate Bond Index.
Performance, One Year or Less	rr_PerformanceOneYearOrLess	No performance is shown because the Account has not yet had a calendar year of performance.
Bond Market Index Account (Prospectus Summary) | Bond Market Index Account | Class 1
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.02%	[1]
Total Annual Account Operating Expenses	rr_ExpensesOverAssets	0.27%
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	28
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	87

[1] Other expenses estimated for the year ending December 31, 2012.