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Label Element Value
Risk Return [Abstract] rr_RiskReturnAbstract  
ProspectusDate rr_ProspectusDate Apr. 30, 2012
Principal LifeTime 2050 Account (Prospectus Summary) | Principal LifeTime 2050 Account
  
Risk Return [Abstract] rr_RiskReturnAbstract  
Risk/Return, Heading rr_RiskReturnHeading Principal LifeTime 2050 Account
Investment Objective, Heading rr_ObjectiveHeading Objective:
investment Objective, Primary rr_ObjectivePrimaryTextBlock The Account seeks a total return consisting of long-term growth of capital and 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 As a fund of funds, the Account does not pay transaction costs, such as
commissions, when it buys and sells shares of underlying funds (or "turns over"
its portfolio). An underlying fund does pay transaction costs when it buys and
sells portfolio securities, and a higher portfolio turnover may indicate higher
transaction costs. These costs, which are not reflected in annual account
operating expenses or in the examples, affect the performance of the underlying
fund and the Account. During its most recent fiscal year, the Account's
portfolio turnover rate was 19.7% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 19.70%
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 The Account operates as a "target date fund." It invests in underlying Principal
Funds, Inc. ("PFI") domestic and foreign equity, real asset and alternative
investments, and fixed-income Funds and other Principal Variable Contracts
Funds, Inc. ("PVC") Accounts according to an asset allocation strategy designed
for investors having a retirement investment goal close to the year in the
Account's name. The Account's asset allocation will become more conservative
over time as investment goals near (for example, retirement, which is assumed to
begin at age 65) and investors become more risk-averse. The Account invests in
PFI Institutional Class and PVC Class 1 shares of underlying funds. It is
managed by Principal Management Corporation ("Principal"); Principal has hired a
sub-advisor, Principal Global Investors, LLC ("PGI"), to assist in managing the
Account.

Principal, with assistance from PGI, develops, implements and monitors the
Account's strategic or long-term asset class targets and target ranges, is also
responsible for an active rebalancing strategy designed to identify asset
classes that appear attractive over the short term and sets the percentage of
Account assets to be allocated to a particular asset class. Principal selects
the underlying funds for each asset class and the target weights for each
underlying fund. Principal, with assistance from PGI, may shift asset class
targets in response to normal evaluative processes, the shortening time horizon
of the Account or changes in market forces or Account circumstances. Principal
may add, remove, or substitute underlying funds at any time.
  
In selecting underlying funds and target weights, Principal considers both
quantitative measures (e.g., past performance, expected levels of risk and
returns, expense levels, diversification and style consistency) and qualitative
factors (e.g., organizational stability, investment experience, investment and
risk management processes, and information, trading, and compliance systems).
There are no minimum or maximum percentages of assets that the Account must
invest in a specific asset class or underlying fund. Underlying funds may
utilize derivatives.

Within 10 to 15 years after its target year, the Account's underlying fund
allocation is expected to match that of the Principal LifeTime Strategic Income
Account. At that time, the Account may be combined with the Principal LifeTime
Strategic Income Account if the Board of Directors determines that the
combination is in the best interests of Account shareholders. It is expected
that at the target date in the Account's name, the shareholder will begin
gradually withdrawing the account's value.

PRINCIPAL LIFETIME ACCOUNTS GLIDE PATH*

Target Allocations Over Time     
  Target Date (Assumed Retirement) Non-U.S. Equity  U.S. Equity  Real Assets/Other**  Fixed Income
  % of Total Assets                    13%               31%               9%              47%

15 Years after Retirement          Non-U.S. Equity  U.S. Equity  Real Asset/Other**   Fixed Income
  % of Total Assets                    6%                14%               12%             68%

*As of March 31, 2012

** Shareholders receive exposure to real assets through the underlying Diversified Real Asset Fund.
Also included is the underlying Global Diversified Income Fund, used for the purpose of enhancing
income potential and providing some additional diversification.  Finally, shareholders receive
exposure to alternative strategies designed to potentially achieve long-term capital appreciation with
an emphasis on striving for positive total returns and relatively low volatility through the underlying
Global Multi-Strategy Fund.
Risk, Heading rr_RiskHeading Principal Risks
Risk, Narrative rr_RiskNarrativeTextBlock The broad diversification of the Account is designed to cushion severe losses in
any one investment sector and moderate overall price volatility. However, the
Account is subject to the particular risks of the underlying funds in the
proportions in which the Account invests in them, and its share prices will
fluctuate as the prices of underlying fund shares rise or fall with changing
market conditions. If you sell your shares when their value is less than the
price you paid, you will lose money. The Account operates as a fund of funds and
thus bears both its own expenses and, indirectly, its proportionate share of the
expenses of the underlying funds in which it invests. 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 that are inherent in the fund of
funds, in alphabetical order, are:

Asset Allocation Risk. A fund's selection and weighting of asset classes may
cause it to underperform other funds with a similar investment objective.
  
Conflict of Interest Risk. The Advisor and its affiliates earn different fees
from different underlying funds and may have an incentive to allocate more
fund-of-fund assets to underlying funds from which they receive higher fees.
  
Investment Company Securities Risk. Fund shareholders bear indirectly their
proportionate share of the expenses of other investment companies in which the
fund invests.

Target Date Fund Risk. There is no guarantee that this fund will provide
adequate income at or through retirement.

The principal risks of investing in the Account that are inherent in the
underlying funds, 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.

Derivatives Risk. Transactions in derivatives (such as options, futures,
currency contracts, and swaps) may increase volatility, cause the liquidation of
portfolio positions when not advantageous to do so and produce disproportionate
losses.

Emerging Market Risk. Investments in emerging market countries may have more
risk than those in developed market countries because the emerging markets are
less developed and more illiquid. Emerging market countries can also be subject
to increased social, economic, regulatory, and political uncertainties and can
be extremely volatile.

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.

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.

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.

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.

Investment Company Securities Risk. Fund shareholders bear indirectly their
proportionate share of the expenses of other investment companies in which the
fund invests.

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 Investment Trusts ("REITs") Risk. A REIT could fail to qualify for
tax-free pass-through of income under the Internal Revenue Code, and fund
shareholders will indirectly bear their proportionate share of the expenses of
REITs in which the fund invests.

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.
  
Value Stock Risk. The market may not recognize the intrinsic value of value
stocks for a long time, or they may be appropriately priced at the time of
purchase.
Risk, Lose Money rr_RiskLoseMoney If you sell your shares when their value is less than the price you paid, you will lose money.
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.
  
The MSCI - EAFE Index NDTR D is used to show international stock performance.
The Barclays Capital Aggregate Bond Index is used to show performance of
domestic, taxable fixed-income securities. Performance of a blended index shows
how the Account's performance compares to an index with similar investment
objectives, and performance of the components of the blended index are also
shown. Effective March 31, 2012, the weightings for the Principal LifeTime 2050
Blended Index were 65.9% Russell 3000 Index, 27.6% MSCI - EAFE Index NDTR D, and
6.5% Barclays Capital Aggregate Bond Index. The custom or blended index returns
reflect the allocation in effect for the time period(s) for which fund returns
are disclosed. Previous weightings or allocations of the custom or blended index
are not restated.
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, Additional Market Index rr_PerformanceAdditionalMarketIndex The MSCI - EAFE Index NDTR D is used to show international stock performance. The Barclays Capital Aggregate Bond Index is used to show performance of domestic, taxable fixed-income securities. Performance of a blended index shows how the Account's performance compares to an index with similar investment objectives, and performance of the components of the blended index are also shown. Effective March 31, 2012, the weightings for the Principal LifeTime 2050 Blended Index were 65.9% Russell 3000 Index, 27.6% MSCI - EAFE Index NDTR D, and 6.5% Barclays Capital Aggregate Bond Index. The custom or blended index returns reflect the allocation in effect for the time period(s) for which fund returns are disclosed. Previous weightings or allocations of the custom or blended index are not restated.
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                             
chart above:                                                      Q2 '09        17.92 %
Lowest return for a quarter during the period of the bar                              
chart above:                                                      Q4 '08       -22.08 %
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
Principal LifeTime 2050 Account (Prospectus Summary) | Principal LifeTime 2050 Account | Barclays Capital Aggregate Bond Index
  
Risk Return [Abstract] rr_RiskReturnAbstract  
Average Annual Returns, Label rr_AverageAnnualReturnLabel Barclays Capital Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 7.84%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 6.50%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 5.55%
Principal LifeTime 2050 Account (Prospectus Summary) | Principal LifeTime 2050 Account | MSCI - EAFE Index NDTR D
  
Risk Return [Abstract] rr_RiskReturnAbstract  
Average Annual Returns, Label rr_AverageAnnualReturnLabel MSCI - EAFE Index NDTR D (reflects no deduction for fees, expenses, or taxes)
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 (12.14%)
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 (4.72%)
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 3.98%
Principal LifeTime 2050 Account (Prospectus Summary) | Principal LifeTime 2050 Account | Russell 3000 Index
  
Risk Return [Abstract] rr_RiskReturnAbstract  
Average Annual Returns, Label rr_AverageAnnualReturnLabel Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 1.03%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 (0.01%)
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 4.48%
Principal LifeTime 2050 Account (Prospectus Summary) | Principal LifeTime 2050 Account | Principal LifeTime 2050 Blended Index
  
Risk Return [Abstract] rr_RiskReturnAbstract  
Average Annual Returns, Label rr_AverageAnnualReturnLabel Principal LifeTime 2050 Blended Index (reflects no deduction for fees, expenses, or taxes)
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 (2.14%)
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 (0.51%)
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 4.25%
Principal LifeTime 2050 Account (Prospectus Summary) | Principal LifeTime 2050 Account | Class 1
  
Risk Return [Abstract] rr_RiskReturnAbstract  
Management Fees rr_ManagementFeesOverAssets 0.03%
Other Expenses rr_OtherExpensesOverAssets 0.04%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.68%
Total Annual Account Operating Expenses rr_ExpensesOverAssets 0.75%
Expense Example, With Redemption, 1 Year rr_ExpenseExampleYear01 77
Expense Example, With Redemption, 3 Years rr_ExpenseExampleYear03 240
Expense Example, With Redemption, 5 Years rr_ExpenseExampleYear05 417
Expense Example, With Redemption, 10 Years rr_ExpenseExampleYear10 930
Annual Return 2005 rr_AnnualReturn2005 7.56%
Annual Return 2006 rr_AnnualReturn2006 15.49%
Annual Return 2007 rr_AnnualReturn2007 6.62%
Annual Return 2008 rr_AnnualReturn2008 (39.05%)
Annual Return 2009 rr_AnnualReturn2009 30.04%
Annual Return 2010 rr_AnnualReturn2010 16.21%
Annual Return 2011 rr_AnnualReturn2011 (3.94%)
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 17.92%
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 (22.08%)
Average Annual Returns, Label rr_AverageAnnualReturnLabel Principal LifeTime 2050 - Class 1
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 (3.94%)
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 (1.16%)
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 3.74%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Aug. 30, 2004