Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Apr. 30, 2012
LargeCap Growth Account I (Prospectus Summary) | LargeCap Growth Account I
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	LargeCap Growth Account I
Investment Objective, Heading	rr_ObjectiveHeading	Objective:
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Account seeks long-term growth of capital.
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. During the most recent fiscal year, the Account's portfolio turnover rate was 46.1% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	46.10%
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 equity securities of companies with large market capitalizations (those with market capitalization ranges similar to the companies in the Russell 1000® Growth Index (as of December 31, 2011, this range was between approximately $117 million and $401.25 billion)) at the time of purchase. The Account invests in growth equity securities; growth orientation emphasizes buying equity securities of companies whose potential for growth of capital and earnings is expected to be above average. The Account may also invest in securities of foreign companies. Principal Management Corporation invests between 10% and 40% of the Account's assets in equity securities in an attempt to match or exceed the performance of the Account's benchmark index by purchasing securities in the index while slightly overweighting and underweighting certain individual equity securities relative to their weight in the Account's benchmark index.
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	The Account may be an appropriate investment for investors seeking long-term growth of capital and willing to accept the risks of investing in equity securities that may have greater risks than equity securities of companies with lower potential for earnings growth. 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: Currency Risk.  Risks of investing in securities denominated in, or that trade in, foreign (non-U.S.) currencies include changes in foreign exchange rates and foreign exchange restrictions. Equity Securities Risk. Equity securities (common, convertible preferred stocks and other securities whose values are tied to the price of stocks, such as rights, warrants and convertible debt securities) could decline in value if the issuer's financial condition declines or in response to overall market and economic conditions. A fund's principal market segment(s), such as large cap, mid cap or small cap stocks, or growth or value stocks, may underperform other market segments or the equity markets as a whole. Investments in smaller companies and mid-size companies may involve greater risk and price volatility than investments in larger, more mature companies. Foreign Securities Risk. The risks of foreign securities include loss of value as a result of: political or economic instability; nationalization, expropriation or confiscatory taxation; settlement delays; and limited government regulation (including less stringent reporting, accounting, and disclosure standards than are required of U.S. companies). Growth Stock Risk. If growth companies do not increase their earnings at a rate expected by investors, the market price of the stock may decline significantly, even if earnings show an absolute increase. Growth company stocks also typically lack the dividend yield that can lessen price declines in market downturns. 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.
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	The following information provides some indication of the risks of investing in the Account by showing changes in the Account's performance from year to year and by showing how the Account's average annual returns for 1, 5, and 10 years (or, if shorter, the life of the Account) compare with those of one or more broad measures of market performance. Past performance is not necessarily an indication of how the Account will perform in the future. Performance figures for the Accounts do not include any separate account expenses, cost of insurance, or other contract-level expenses; total returns for the Accounts would be lower if such expenses were included.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Account by showing changes in the Account's performance from year to year and by showing how the Account's average annual returns for 1, 5, and 10 years (or, if shorter, the life of the Account) compare with those of one or more broad measures of market performance.
Performance, Past Does Not Indicate Future	rr_PerformancePastDoesNotIndicateFuture	Past performance is not necessarily an indication of how the Account will perform in the future.
Bar Chart, Heading	rr_BarChartHeading	Calendar Year Total Returns (%) as of 12/31 each year (Class 1 Shares)
Bar Chart, Closing	rr_BarChartClosingTextBlock	Highest return for a quarter during the period of the bar       Q2 '09    19.90% chart above:                                                            Lowest return for a quarter during the period of the bar        Q4 '08   -22.69% chart above:
Index No Deduction for Fees, Expenses, Taxes	rr_IndexNoDeductionForFeesExpensesTaxes	reflects no deduction for fees, expenses, or taxes
Average Annual Returns, Caption	rr_AverageAnnualReturnCaption	Average Annual Total Returns (%) For the periods ended December 31, 2011
LargeCap Growth Account I (Prospectus Summary) | LargeCap Growth Account I | Russell 1000 Growth Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Russell 1000 Growth Index (reflects no deduction for fees, expenses, or taxes)
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	2.64%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	2.50%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	2.60%
LargeCap Growth Account I (Prospectus Summary) | LargeCap Growth Account I | Class 1
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.76%
Other Expenses	rr_OtherExpensesOverAssets	0.02%
Total Annual Account Operating Expenses	rr_ExpensesOverAssets	0.78%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	(0.02%)	[1]
Total Annual Account Operating Expenses after Fee Waiver	rr_NetExpensesOverAssets	0.76%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	78
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	246
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	431
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	964
Annual Return 2002	rr_AnnualReturn2002	(27.72%)
Annual Return 2003	rr_AnnualReturn2003	25.95%
Annual Return 2004	rr_AnnualReturn2004	9.33%
Annual Return 2005	rr_AnnualReturn2005	7.55%
Annual Return 2006	rr_AnnualReturn2006	6.21%
Annual Return 2007	rr_AnnualReturn2007	8.52%
Annual Return 2008	rr_AnnualReturn2008	(40.60%)
Annual Return 2009	rr_AnnualReturn2009	52.71%
Annual Return 2010	rr_AnnualReturn2010	19.61%
Annual Return 2011	rr_AnnualReturn2011	(0.33%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest return for a quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	19.90%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest return for a quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(22.69%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	LargeCap Growth I - Class 1
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(0.33%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	3.25%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	2.93%

[1] Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Account's Management Fees through the period ending April 30, 2013. The fee waiver will reduce the Account's Management Fees by 0.016% (expressed as a percent of average net assets on an annualized basis). It is expected that the fee waiver will continue through the period disclosed; however, Principal Variable Contracts Funds, Inc. and Principal, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.