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PFI Prospectus | Diversified Income Fund  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading SUMMARY FOR DIVERSIFIED INCOME FUND
Strategy [Heading] rr_StrategyHeading Delete the Principal Investment Strategies section, and replace with the following:
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Fund generally invests a majority of its assets in fixed income securities, such as investment-grade corporate bonds, high yield bonds (also known as “junk” bonds), preferred securities, commercial mortgage-backed securities, and emerging market debt securities, in an effort to provide incremental yields over a portfolio of government securities. Such securities include instruments with variable or floating interest rates. The fixed income portion of the Fund is not managed to a particular maturity or duration. The Fund invests in foreign, including emerging market, securities. The Fund uses derivative strategies. A derivative is a financial arrangement, the value of which is derived from, or based on, a traditional security, asset, or market index.
In managing the Fund, Principal Global Investors, LLC (“PGI,” the Fund’s investment advisor), determines the Fund's strategic asset allocation among the general investment categories listed below, which are executed by PGI and multiple sub-advisors. Those selecting investments for the Fund seek to provide yield by focusing on securities that offer the best potential for yield, taking risk into consideration, within their respective investment categories. Some strategies use active management, others use passive (index) or enhanced index strategies, and some use a combination of active and passive strategies. PGI has considerable latitude in allocating the Fund's assets. The Fund uses strategies and sub-advisors to varying degrees and may change allocations, add new or eliminate existing strategies and sub-advisors, and temporarily or permanently reduce allocations from time to time such that the Fund would have little or no assets allocated to a particular strategy or sub-advisor.
•Investment grade corporate securities, which are rated at the time of purchase Baa3 or higher by Moody’s Investors Service (“Moody’s”) or BBB- or higher by S&P Global Ratings (“S&P Global”).
•High yield and other income-producing securities, including bank loans and corporate bonds. “High yield” securities are below investment grade securities (sometimes called “junk”) which are rated at the time of purchase Ba1 or lower by Moody's and BB+ or lower by S&P Global. These securities offer a higher yield than other, higher rated securities, but they carry a greater degree of risk and are considered speculative with respect to the issuer's ability to pay interest and to repay principal. This portion of the Fund also invests in currency forwards and currency options to hedge currency risk.
•Preferred securities, focusing primarily on the financial services and utility industries.
•Diversified portfolio of fixed income securities, including those issued by governments and their agencies and corporate entities in emerging markets. This portion of the Fund also invests in interest rate swaps or Treasury futures to manage fixed income exposure; credit default swaps to increase or decrease in an efficient manner exposures to certain sectors or individual issuers; total return swaps to increase or decrease in an efficient manner exposures to certain sectors; and currency forwards and currency options to hedge currency risk and express views on the direction of currency.
•Securitized products such as asset-backed securities and mortgage-based securities, including commercial mortgage-backed securities, which are bonds secured by first mortgages on commercial real estate.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock In the Principal Risks section, delete the Equity Securities Risk, including Smaller Companies Risk and Value Style Risk, Real Estate Investment Trusts (“REITs”) Risk, and the Real Estate Securities Risk.
PFI Prospectus | Diversified Income Fund | Global Diversified Income Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PGBAX
PFI Prospectus | Diversified Income Fund | Global Diversified Income Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PGDCX
PFI Prospectus | Diversified Income Fund | Global Diversified Income Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PGDIX
PFI Prospectus | Diversified Income Fund | Global Diversified Income Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PGBLX
PFI Prospectus | SmallCap Value Fund II  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading SUMMARY FOR SMALLCAP VALUE FUND II
PFI Prospectus | SmallCap Value Fund II | SmallCap Value Fund II, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSVAX
PFI Prospectus | SmallCap Value Fund II | SmallCap Value Fund II, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSMJX
PFI Prospectus | SmallCap Value Fund II | SmallCap Value Fund II, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPVIX
PFI Prospectus | SmallCap Value Fund II | SmallCap Value Fund II, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCPTX
PFI Prospectus | SmallCap Value Fund II | SmallCap Value Fund II, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PJARX
PFI Prospectus | SmallCap Value Fund II | SmallCap Value Fund II, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSTWX
PFI Prospectus | SmallCap Value Fund II | SmallCap Value Fund II, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLARX
PFI Prospectus | SmallCap Value Fund II | SmallCap Value Fund II, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSMVX
PFI Prospectus | California Municipal Fund  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading California Municipal
PFI Prospectus | California Municipal Fund | California Municipal Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SRCMX
PFI Prospectus | California Municipal Fund | California Municipal Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SRCCX
PFI Prospectus | California Municipal Fund | California Municipal Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCMFX
PFI Prospectus | Core Fixed Income Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Core Fixed Income
PFI Prospectus | Core Fixed Income Fund [Member] | Core Fixed Income Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol CMPIX
PFI Prospectus | Core Fixed Income Fund [Member] | Core Fixed Income Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol CNMCX
PFI Prospectus | Core Fixed Income Fund [Member] | Core Fixed Income Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIOJX
PFI Prospectus | Core Fixed Income Fund [Member] | Core Fixed Income Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIOIX
PFI Prospectus | Core Fixed Income Fund [Member] | Core Fixed Income Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIOMX
PFI Prospectus | Core Fixed Income Fund [Member] | Core Fixed Income Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIOOX
PFI Prospectus | Core Fixed Income Fund [Member] | Core Fixed Income Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIOPX
PFI Prospectus | Core Fixed Income Fund [Member] | Core Fixed Income Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIOQX
PFI Prospectus | Core Fixed Income Fund [Member] | Core Fixed Income Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PICNX
PFI Prospectus | Core Plus Bond Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Core Plus Bond
PFI Prospectus | Core Plus Bond Fund [Member] | Core Plus Bond Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PRBDX
PFI Prospectus | Core Plus Bond Fund [Member] | Core Plus Bond Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PBMJX
PFI Prospectus | Core Plus Bond Fund [Member] | Core Plus Bond Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMSIX
PFI Prospectus | Core Plus Bond Fund [Member] | Core Plus Bond Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PBOMX
PFI Prospectus | Core Plus Bond Fund [Member] | Core Plus Bond Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PBMMX
PFI Prospectus | Core Plus Bond Fund [Member] | Core Plus Bond Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PBMSX
PFI Prospectus | Core Plus Bond Fund [Member] | Core Plus Bond Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PBMPX
PFI Prospectus | Diversified International Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Diversified International
PFI Prospectus | Diversified International Fund [Member] | Diversified International Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PRWLX
PFI Prospectus | Diversified International Fund [Member] | Diversified International Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PDNCX
PFI Prospectus | Diversified International Fund [Member] | Diversified International Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIIJX
PFI Prospectus | Diversified International Fund [Member] | Diversified International Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIIIX
PFI Prospectus | Diversified International Fund [Member] | Diversified International Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PDVIX
PFI Prospectus | Diversified International Fund [Member] | Diversified International Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PINRX
PFI Prospectus | Diversified International Fund [Member] | Diversified International Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PINLX
PFI Prospectus | Diversified International Fund [Member] | Diversified International Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PINPX
PFI Prospectus | Diversified International Fund [Member] | Diversified International Fund, Class R-6  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PDIFX
PFI Prospectus | Equity Income Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Equity Income
PFI Prospectus | Equity Income Fund [Member] | Equity Income Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PQIAX
PFI Prospectus | Equity Income Fund [Member] | Equity Income Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PEUCX
PFI Prospectus | Equity Income Fund [Member] | Equity Income Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PEIIX
PFI Prospectus | Equity Income Fund [Member] | Equity Income Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIEMX
PFI Prospectus | Equity Income Fund [Member] | Equity Income Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PEIOX
PFI Prospectus | Equity Income Fund [Member] | Equity Income Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PEIPX
PFI Prospectus | Equity Income Fund [Member] | Equity Income Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PEIQX
PFI Prospectus | Finisterre Emerging Markets Total Return Bond Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Finisterre Emerging Markets Total Return Bond
PFI Prospectus | Finisterre Emerging Markets Total Return Bond Fund [Member] | Finisterre Emerging Markets Total Return Bond Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PFUEX
PFI Prospectus | Finisterre Emerging Markets Total Return Bond Fund [Member] | Finisterre Emerging Markets Total Return Bond Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PFUMX
PFI Prospectus | Global Real Estate Securities Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Global Real Estate Securities
PFI Prospectus | Global Real Estate Securities Fund [Member] | Global Real Estate Securities Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol POSAX
PFI Prospectus | Global Real Estate Securities Fund [Member] | Global Real Estate Securities Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol POSCX
PFI Prospectus | Global Real Estate Securities Fund [Member] | Global Real Estate Securities Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol POSIX
PFI Prospectus | Global Real Estate Securities Fund [Member] | Global Real Estate Securities Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PGRKX
PFI Prospectus | Global Real Estate Securities Fund [Member] | Global Real Estate Securities Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PGRVX
PFI Prospectus | Global Real Estate Securities Fund [Member] | Global Real Estate Securities Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PGRUX
PFI Prospectus | Global Real Estate Securities Fund [Member] | Global Real Estate Securities Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PGRSX
PFI Prospectus | Government & High Quality Bond Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Government & High Quality Bond
PFI Prospectus | Government & High Quality Bond Fund [Member] | Government & High Quality Bond Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol CMPGX
PFI Prospectus | Government & High Quality Bond Fund [Member] | Government & High Quality Bond Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol CCUGX
PFI Prospectus | Government & High Quality Bond Fund [Member] | Government & High Quality Bond Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMRJX
PFI Prospectus | Government & High Quality Bond Fund [Member] | Government & High Quality Bond Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMRIX
PFI Prospectus | Government & High Quality Bond Fund [Member] | Government & High Quality Bond Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMGRX
PFI Prospectus | Government & High Quality Bond Fund [Member] | Government & High Quality Bond Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PRCMX
PFI Prospectus | Government & High Quality Bond Fund [Member] | Government & High Quality Bond Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMRDX
PFI Prospectus | Government & High Quality Bond Fund [Member] | Government & High Quality Bond Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMREX
PFI Prospectus | Government Money Market Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Government Money Market
PFI Prospectus | Government Money Market Fund [Member] | Government Money Market Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PGVXX
PFI Prospectus | High Income Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading High Income
PFI Prospectus | High Income Fund [Member] | High Income Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PYHIX
PFI Prospectus | High Yield Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading High Yield
PFI Prospectus | High Yield Fund [Member] | High Yield Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol CPHYX
PFI Prospectus | High Yield Fund [Member] | High Yield Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol CCHIX
PFI Prospectus | High Yield Fund [Member] | High Yield Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHYTX
PFI Prospectus | High Yield Fund [Member] | High Yield Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHYFX
PFI Prospectus | Inflation Protection Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Inflation Protection
PFI Prospectus | Inflation Protection Fund [Member] | Inflation Protection Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PITAX
PFI Prospectus | Inflation Protection Fund [Member] | Inflation Protection Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIPJX
PFI Prospectus | Inflation Protection Fund [Member] | Inflation Protection Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIPIX
PFI Prospectus | Inflation Protection Fund [Member] | Inflation Protection Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PISPX
PFI Prospectus | Inflation Protection Fund [Member] | Inflation Protection Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIFPX
PFI Prospectus | Inflation Protection Fund [Member] | Inflation Protection Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIFSX
PFI Prospectus | Inflation Protection Fund [Member] | Inflation Protection Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PBPPX
PFI Prospectus | International Emerging Markets Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading International Emerging Markets
PFI Prospectus | International Emerging Markets Fund [Member] | International Emerging Markets Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PRIAX
PFI Prospectus | International Emerging Markets Fund [Member] | International Emerging Markets Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMKCX
PFI Prospectus | International Emerging Markets Fund [Member] | International Emerging Markets Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIEJX
PFI Prospectus | International Emerging Markets Fund [Member] | International Emerging Markets Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIEIX
PFI Prospectus | International Emerging Markets Fund [Member] | International Emerging Markets Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIXEX
PFI Prospectus | International Emerging Markets Fund [Member] | International Emerging Markets Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PEAPX
PFI Prospectus | International Emerging Markets Fund [Member] | International Emerging Markets Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PESSX
PFI Prospectus | International Emerging Markets Fund [Member] | International Emerging Markets Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PEPSX
PFI Prospectus | International Emerging Markets Fund [Member] | International Emerging Markets Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIIMX
PFI Prospectus | International Fund I [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading International I
PFI Prospectus | International Fund I [Member] | International Fund I, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PFAFX
PFI Prospectus | International Fund I [Member] | International Fund I, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PINIX
PFI Prospectus | International Fund I [Member] | International Fund I, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPISX
PFI Prospectus | International Fund I [Member] | International Fund I, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PRPPX
PFI Prospectus | International Fund I [Member] | International Fund I, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PUPPX
PFI Prospectus | International Fund I [Member] | International Fund I, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTPPX
PFI Prospectus | International Fund I [Member] | International Fund I, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIIDX
PFI Prospectus | LargeCap Growth Fund I [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading LargeCap Growth I
PFI Prospectus | LargeCap Growth Fund I [Member] | LargeCap Growth Fund I, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLGAX
PFI Prospectus | LargeCap Growth Fund I [Member] | LargeCap Growth Fund I, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLGJX
PFI Prospectus | LargeCap Growth Fund I [Member] | LargeCap Growth Fund I, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLGIX
PFI Prospectus | LargeCap Growth Fund I [Member] | LargeCap Growth Fund I, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCRSX
PFI Prospectus | LargeCap Growth Fund I [Member] | LargeCap Growth Fund I, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPUMX
PFI Prospectus | LargeCap Growth Fund I [Member] | LargeCap Growth Fund I, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPUSX
PFI Prospectus | LargeCap Growth Fund I [Member] | LargeCap Growth Fund I, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPUPX
PFI Prospectus | LargeCap Growth Fund I [Member] | LargeCap Growth Fund I, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLCGX
PFI Prospectus | LargeCap S&P 500 Index Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading LargeCap S&P 500 Index
PFI Prospectus | LargeCap S&P 500 Index Fund [Member] | LargeCap S&P 500 Index Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLSAX
PFI Prospectus | LargeCap S&P 500 Index Fund [Member] | LargeCap S&P 500 Index Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLICX
PFI Prospectus | LargeCap S&P 500 Index Fund [Member] | LargeCap S&P 500 Index Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSPJX
PFI Prospectus | LargeCap S&P 500 Index Fund [Member] | LargeCap S&P 500 Index Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLFIX
PFI Prospectus | LargeCap S&P 500 Index Fund [Member] | LargeCap S&P 500 Index Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLPIX
PFI Prospectus | LargeCap S&P 500 Index Fund [Member] | LargeCap S&P 500 Index Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLFMX
PFI Prospectus | LargeCap S&P 500 Index Fund [Member] | LargeCap S&P 500 Index Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLFSX
PFI Prospectus | LargeCap S&P 500 Index Fund [Member] | LargeCap S&P 500 Index Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLFPX
PFI Prospectus | LargeCap Value Fund III [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading LargeCap Value III
PFI Prospectus | LargeCap Value Fund III [Member] | LargeCap Value Fund III, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLVJX
PFI Prospectus | LargeCap Value Fund III [Member] | LargeCap Value Fund III, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLVIX
PFI Prospectus | LargeCap Value Fund III [Member] | LargeCap Value Fund III, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PESAX
PFI Prospectus | LargeCap Value Fund III [Member] | LargeCap Value Fund III, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPSFX
PFI Prospectus | LargeCap Value Fund III [Member] | LargeCap Value Fund III, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPSSX
PFI Prospectus | LargeCap Value Fund III [Member] | LargeCap Value Fund III, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPSRX
PFI Prospectus | MidCap Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading MidCap
PFI Prospectus | MidCap Fund [Member] | MidCap Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PEMGX
PFI Prospectus | MidCap Fund [Member] | MidCap Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMBCX
PFI Prospectus | MidCap Fund [Member] | MidCap Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMBJX
PFI Prospectus | MidCap Fund [Member] | MidCap Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCBIX
PFI Prospectus | MidCap Fund [Member] | MidCap Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMSBX
PFI Prospectus | MidCap Fund [Member] | MidCap Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMBMX
PFI Prospectus | MidCap Fund [Member] | MidCap Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMBSX
PFI Prospectus | MidCap Fund [Member] | MidCap Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMBPX
PFI Prospectus | MidCap Fund [Member] | MidCap Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMAQX
PFI Prospectus | MidCap Growth Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading MidCap Growth
PFI Prospectus | MidCap Growth Fund [Member] | MidCap Growth Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMGJX
PFI Prospectus | MidCap Growth Fund [Member] | MidCap Growth Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PGWIX
PFI Prospectus | MidCap Growth Fund [Member] | MidCap Growth Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMSGX
PFI Prospectus | MidCap Growth Fund [Member] | MidCap Growth Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PFPPX
PFI Prospectus | MidCap Growth Fund [Member] | MidCap Growth Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIPPX
PFI Prospectus | MidCap Growth Fund [Member] | MidCap Growth Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHPPX
PFI Prospectus | MidCap Growth Fund III [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading MidCap Growth III
PFI Prospectus | MidCap Growth Fund III [Member] | MidCap Growth Fund III, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPQJX
PFI Prospectus | MidCap Growth Fund III [Member] | MidCap Growth Fund III, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPIMX
PFI Prospectus | MidCap Growth Fund III [Member] | MidCap Growth Fund III, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHASX
PFI Prospectus | MidCap Growth Fund III [Member] | MidCap Growth Fund III, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPQMX
PFI Prospectus | MidCap Growth Fund III [Member] | MidCap Growth Fund III, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPQSX
PFI Prospectus | MidCap Growth Fund III [Member] | MidCap Growth Fund III, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPQPX
PFI Prospectus | MidCap S&P 400 Index Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading MidCap S&P 400 Index
PFI Prospectus | MidCap S&P 400 Index Fund [Member] | MidCap S&P 400 Index Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMFJX
PFI Prospectus | MidCap S&P 400 Index Fund [Member] | MidCap S&P 400 Index Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol MPSIX
PFI Prospectus | MidCap S&P 400 Index Fund [Member] | MidCap S&P 400 Index Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMSSX
PFI Prospectus | MidCap S&P 400 Index Fund [Member] | MidCap S&P 400 Index Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMFMX
PFI Prospectus | MidCap S&P 400 Index Fund [Member] | MidCap S&P 400 Index Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMFSX
PFI Prospectus | MidCap S&P 400 Index Fund [Member] | MidCap S&P 400 Index Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMFPX
PFI Prospectus | MidCap S&P 400 Index Fund [Member] | MidCap S&P 400 Index Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMAPX
PFI Prospectus | MidCap Value Fund I [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading MidCap Value I
PFI Prospectus | MidCap Value Fund I [Member] | MidCap Value Fund I, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCMVX
PFI Prospectus | MidCap Value Fund I [Member] | MidCap Value Fund I, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PVEJX
PFI Prospectus | MidCap Value Fund I [Member] | MidCap Value Fund I, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PVMIX
PFI Prospectus | MidCap Value Fund I [Member] | MidCap Value Fund I, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLASX
PFI Prospectus | MidCap Value Fund I [Member] | MidCap Value Fund I, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMPRX
PFI Prospectus | MidCap Value Fund I [Member] | MidCap Value Fund I, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PABWX
PFI Prospectus | MidCap Value Fund I [Member] | MidCap Value Fund I, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PABVX
PFI Prospectus | MidCap Value Fund I [Member] | MidCap Value Fund I , Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCMSX
PFI Prospectus | Money Market Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Money Market
PFI Prospectus | Money Market Fund [Member] | Money Market Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCSXX
PFI Prospectus | Money Market Fund [Member] | Money Market Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMJXX
PFI Prospectus | Overseas Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Overseas
PFI Prospectus | Overseas Fund [Member] | Overseas Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PINZX
PFI Prospectus | Overseas Fund [Member] | Overseas Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PINQX
PFI Prospectus | Overseas Fund [Member] | Overseas Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PINTX
PFI Prospectus | Overseas Fund [Member] | Overseas Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PINUX
PFI Prospectus | Overseas Fund [Member] | Overseas Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PINGX
PFI Prospectus | Principal Capital Appreciation Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal Capital Appreciation
PFI Prospectus | Principal Capital Appreciation Fund [Member] | Principal Capital Appreciation Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol CMNWX
PFI Prospectus | Principal Capital Appreciation Fund [Member] | Principal Capital Appreciation Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol CMNCX
PFI Prospectus | Principal Capital Appreciation Fund [Member] | Principal Capital Appreciation Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PWCIX
PFI Prospectus | Principal Capital Appreciation Fund [Member] | Principal Capital Appreciation Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCAMX
PFI Prospectus | Principal Capital Appreciation Fund [Member] | Principal Capital Appreciation Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCAOX
PFI Prospectus | Principal Capital Appreciation Fund [Member] | Principal Capital Appreciation Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCAPX
PFI Prospectus | Principal Capital Appreciation Fund [Member] | Principal Capital Appreciation Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCAQX
PFI Prospectus | Principal LifeTime Strategic Income Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Strategic Income
PFI Prospectus | Principal LifeTime Strategic Income Fund [Member] | Principal LifeTime Strategic Income Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PALTX
PFI Prospectus | Principal LifeTime Strategic Income Fund [Member] | Principal LifeTime Strategic Income Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLSJX
PFI Prospectus | Principal LifeTime Strategic Income Fund [Member] | Principal LifeTime Strategic Income Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLSIX
PFI Prospectus | Principal LifeTime Strategic Income Fund [Member] | Principal LifeTime Strategic Income Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLAIX
PFI Prospectus | Principal LifeTime Strategic Income Fund [Member] | Principal LifeTime Strategic Income Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLSMX
PFI Prospectus | Principal LifeTime Strategic Income Fund [Member] | Principal LifeTime Strategic Income Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLSSX
PFI Prospectus | Principal LifeTime Strategic Income Fund [Member] | Principal LifeTime Strategic Income Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLSPX
PFI Prospectus | Principal LifeTime 2010 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime 2010
PFI Prospectus | Principal LifeTime 2010 Fund [Member] | Principal Lifetime 2010 Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PENAX
PFI Prospectus | Principal LifeTime 2010 Fund [Member] | Principal Lifetime 2010 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTAJX
PFI Prospectus | Principal LifeTime 2010 Fund [Member] | Principal Lifetime 2010 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTTIX
PFI Prospectus | Principal LifeTime 2010 Fund [Member] | Principal Lifetime 2010 Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PVASX
PFI Prospectus | Principal LifeTime 2010 Fund [Member] | Principal Lifetime 2010 Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTAMX
PFI Prospectus | Principal LifeTime 2010 Fund [Member] | Principal Lifetime 2010 Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTASX
PFI Prospectus | Principal LifeTime 2010 Fund [Member] | Principal Lifetime 2010 Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTAPX
PFI Prospectus | Principal LifeTime 2015 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime 2015
PFI Prospectus | Principal LifeTime 2015 Fund [Member] | Principal LifeTime 2015 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTINX
PFI Prospectus | Principal LifeTime 2015 Fund [Member] | Principal LifeTime 2015 Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTSGX
PFI Prospectus | Principal LifeTime 2015 Fund [Member] | Principal LifeTime 2015 Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTAPX
PFI Prospectus | Principal LifeTime 2015 Fund [Member] | Principal LifeTime 2015 Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTSLX
PFI Prospectus | Principal LifeTime 2015 Fund [Member] | Principal LifeTime 2015 Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTPFX
PFI Prospectus | Principal LifeTime 2020 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime 2020
PFI Prospectus | Principal LifeTime 2020 Fund [Member] | Principal LifeTime 2020 Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTBAX
PFI Prospectus | Principal LifeTime 2020 Fund [Member] | Principal LifeTime 2020 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLFJX
PFI Prospectus | Principal LifeTime 2020 Fund [Member] | Principal LifeTime 2020 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLWIX
PFI Prospectus | Principal LifeTime 2020 Fund [Member] | Principal LifeTime 2020 Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PWASX
PFI Prospectus | Principal LifeTime 2020 Fund [Member] | Principal LifeTime 2020 Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTBMX
PFI Prospectus | Principal LifeTime 2020 Fund [Member] | Principal LifeTime 2020 Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTBSX
PFI Prospectus | Principal LifeTime 2020 Fund [Member] | Principal LifeTime 2020 Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTBPX
PFI Prospectus | Principal LifeTime 2025 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime 2025
PFI Prospectus | Principal LifeTime 2025 Fund [Member] | Principal LifeTime 2025 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTSTX
PFI Prospectus | Principal LifeTime 2025 Fund [Member] | Principal LifeTime 2025 Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTSNX
PFI Prospectus | Principal LifeTime 2025 Fund [Member] | Principal LifeTime 2025 Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTVPX
PFI Prospectus | Principal LifeTime 2025 Fund [Member] | Principal LifeTime 2025 Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTEEX
PFI Prospectus | Principal LifeTime 2025 Fund [Member] | Principal LifeTime 2025 Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTPDX
PFI Prospectus | Principal LifeTime 2030 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime 2030
PFI Prospectus | Principal LifeTime 2030 Fund [Member] | Principal LifeTime 2030 Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTCAX
PFI Prospectus | Principal LifeTime 2030 Fund [Member] | Principal LifeTime 2030 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLTJX
PFI Prospectus | Principal LifeTime 2030 Fund [Member] | Principal LifeTime 2030 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PMTIX
PFI Prospectus | Principal LifeTime 2030 Fund [Member] | Principal LifeTime 2030 Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PXASX
PFI Prospectus | Principal LifeTime 2030 Fund [Member] | Principal LifeTime 2030 Fund, Class R-3, [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTCMX
PFI Prospectus | Principal LifeTime 2030 Fund [Member] | Principal LifeTime 2030 Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTCSX
PFI Prospectus | Principal LifeTime 2030 Fund [Member] | Principal LifeTime 2030 Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTCPX
PFI Prospectus | Principal LifeTime 2035 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime 2035
PFI Prospectus | Principal LifeTime 2035 Fund [Member] | Principal LifeTime 2035 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTIUX
PFI Prospectus | Principal LifeTime 2035 Fund [Member] | Principal LifeTime 2035 Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTANX
PFI Prospectus | Principal LifeTime 2035 Fund [Member] | Principal LifeTime 2035 Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTAOX
PFI Prospectus | Principal LifeTime 2035 Fund [Member] | Principal LifeTime 2035 Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTSEX
PFI Prospectus | Principal LifeTime 2035 Fund [Member] | Principal LifeTime 2035 Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTPEX
PFI Prospectus | Principal LifeTime 2040 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime 2040
PFI Prospectus | Principal LifeTime 2040 Fund [Member] | Principal LifeTime 2040 Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTDAX
PFI Prospectus | Principal LifeTime 2040 Fund [Member] | Principal LifeTime 2040 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTDJX
PFI Prospectus | Principal LifeTime 2040 Fund [Member] | Principal LifeTime 2040 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTDIX
PFI Prospectus | Principal LifeTime 2040 Fund [Member] | Principal LifeTime 2040 Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PYASX
PFI Prospectus | Principal LifeTime 2040 Fund [Member] | Principal LifeTime 2040 Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTDMX
PFI Prospectus | Principal LifeTime 2040 Fund [Member] | Principal LifeTime 2040 Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTDSX
PFI Prospectus | Principal LifeTime 2040 Fund [Member] | Principal LifeTime 2040 Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTDPX
PFI Prospectus | Principal LifeTime 2045 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime 2045
PFI Prospectus | Principal LifeTime 2045 Fund [Member] | Principal LifeTime 2045 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTRIX
PFI Prospectus | Principal LifeTime 2045 Fund [Member] | Principal LifeTime 2045 Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTRGX
PFI Prospectus | Principal LifeTime 2045 Fund [Member] | Principal LifeTime 2045 Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTRVX
PFI Prospectus | Principal LifeTime 2045 Fund [Member] | Principal LifeTime 2045 Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTRLX
PFI Prospectus | Principal LifeTime 2045 Fund [Member] | Principal LifeTime 2045 Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTRDX
PFI Prospectus | Principal LifeTime 2050 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime 2050
PFI Prospectus | Principal LifeTime 2050 Fund [Member] | Principal LifeTime 2050 Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPEAX
PFI Prospectus | Principal LifeTime 2050 Fund [Member] | Principal LifeTime 2050 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PFLJX
PFI Prospectus | Principal LifeTime 2050 Fund [Member] | Principal LifeTime 2050 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPLIX
PFI Prospectus | Principal LifeTime 2050 Fund [Member] | Principal LifeTime 2050 Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PZASX
PFI Prospectus | Principal LifeTime 2050 Fund [Member] | Principal LifeTime 2050 Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTERX
PFI Prospectus | Principal LifeTime 2050 Fund [Member] | Principal LifeTime 2050 Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTESX
PFI Prospectus | Principal LifeTime 2050 Fund [Member] | Principal LifeTime 2050 Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTEFX
PFI Prospectus | Principal LifeTime 2055 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime 2055
PFI Prospectus | Principal LifeTime 2055 Fund [Member] | Principal LifeTime 2055 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTFIX
PFI Prospectus | Principal LifeTime 2055 Fund [Member] | Principal LifeTime 2055 Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTFGX
PFI Prospectus | Principal LifeTime 2055 Fund [Member] | Principal LifeTime 2055 Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTFDX
PFI Prospectus | Principal LifeTime 2055 Fund [Member] | Principal LifeTime 2055 Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTFLX
PFI Prospectus | Principal LifeTime 2055 Fund [Member] | Principal LifeTime 2055 Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol LTFPX
PFI Prospectus | Principal LifeTime 2060 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime 2060
PFI Prospectus | Principal LifeTime 2060 Fund [Member] | Principal LifeTime 2060 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLTAX
PFI Prospectus | Principal LifeTime 2060 Fund [Member] | Principal LifeTime 2060 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLTZX
PFI Prospectus | Principal LifeTime 2060 Fund [Member] | Principal LifeTime 2060 Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLTRX
PFI Prospectus | Principal LifeTime 2060 Fund [Member] | Principal LifeTime 2060 Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLTCX
PFI Prospectus | Principal LifeTime 2060 Fund [Member] | Principal LifeTime 2060 Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLTMX
PFI Prospectus | Principal LifeTime 2060 Fund [Member] | Principal LifeTime 2060 Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLTOX
PFI Prospectus | Principal LifeTime 2065 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime 2065
PFI Prospectus | Principal LifeTime 2065 Fund [Member] | Principal LifeTime 2065 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLJIX
PFI Prospectus | Principal LifeTime 2065 Fund [Member] | Principal LifeTime 2065 Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLJAX
PFI Prospectus | Principal LifeTime 2065 Fund [Member] | Principal LifeTime 2065 Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLJCX
PFI Prospectus | Principal LifeTime 2065 Fund [Member] | Principal LifeTime 2065 Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLJDX
PFI Prospectus | Principal LifeTime 2065 Fund [Member] | Principal LifeTime 2065 Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLJEX
PFI Prospectus | Principal LifeTime Hybrid Income Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Hybrid Income
PFI Prospectus | Principal LifeTime Hybrid Income Fund [Member] | Principal LifeTime Hybrid Income Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHJFX
PFI Prospectus | Principal LifeTime Hybrid Income Fund [Member] | Principal LifeTime Hybrid Income Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHTFX
PFI Prospectus | Principal LifeTime Hybrid Income Fund [Member] | Principal LifeTime Hybrid Income Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLTYX
PFI Prospectus | Principal LifeTime Hybrid 2015 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Hybrid 2015
PFI Prospectus | Principal LifeTime Hybrid 2015 Fund [Member] | Principal LifeTime Hybrid 2015 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHJMX
PFI Prospectus | Principal LifeTime Hybrid 2015 Fund [Member] | Principal LifeTime Hybrid 2015 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHTMX
PFI Prospectus | Principal LifeTime Hybrid 2015 Fund [Member] | Principal LifeTime Hybrid 2015 Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLRRX
PFI Prospectus | Principal LifeTime Hybrid 2020 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Hybrid 2020
PFI Prospectus | Principal LifeTime Hybrid 2020 Fund [Member] | Principal LifeTime Hybrid 2020 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHJTX
PFI Prospectus | Principal LifeTime Hybrid 2020 Fund [Member] | Principal LifeTime Hybrid 2020 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHTTX
PFI Prospectus | Principal LifeTime Hybrid 2020 Fund [Member] | Principal LifeTime Hybrid 2020 Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLTTX
PFI Prospectus | Principal LifeTime Hybrid 2025 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Hybrid 2025
PFI Prospectus | Principal LifeTime Hybrid 2025 Fund [Member] | Principal LifeTime Hybrid 2025 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHJQX
PFI Prospectus | Principal LifeTime Hybrid 2025 Fund [Member] | Principal LifeTime Hybrid 2025 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHTQX
PFI Prospectus | Principal LifeTime Hybrid 2025 Fund [Member] | Principal LifeTime Hybrid 2025 Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLFTX
PFI Prospectus | Principal LifeTime Hybrid 2030 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Hybrid 2030
PFI Prospectus | Principal LifeTime Hybrid 2030 Fund [Member] | Principal LifeTime Hybrid 2030 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHJNX
PFI Prospectus | Principal LifeTime Hybrid 2030 Fund [Member] | Principal LifeTime Hybrid 2030 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHTNX
PFI Prospectus | Principal LifeTime Hybrid 2030 Fund [Member] | Principal LifeTime Hybrid 2030 Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLZTX
PFI Prospectus | Principal LifeTime Hybrid 2035 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Hybrid 2035
PFI Prospectus | Principal LifeTime Hybrid 2035 Fund [Member] | Principal LifeTime Hybrid 2035 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHJJX
PFI Prospectus | Principal LifeTime Hybrid 2035 Fund [Member] | Principal LifeTime Hybrid 2035 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHTJX
PFI Prospectus | Principal LifeTime Hybrid 2035 Fund [Member] | Principal LifeTime Hybrid 2035 Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLRTX
PFI Prospectus | Principal LifeTime Hybrid 2040 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Hybrid 2040
PFI Prospectus | Principal LifeTime Hybrid 2040 Fund [Member] | Principal LifeTime Hybrid 2040 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHJEX
PFI Prospectus | Principal LifeTime Hybrid 2040 Fund [Member] | Principal LifeTime Hybrid 2040 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLTQX
PFI Prospectus | Principal LifeTime Hybrid 2040 Fund [Member] | Principal LifeTime Hybrid 2040 Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLMTX
PFI Prospectus | Principal LifeTime Hybrid 2045 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Hybrid 2045
PFI Prospectus | Principal LifeTime Hybrid 2045 Fund [Member] | Principal LifeTime Hybrid 2045 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHJYX
PFI Prospectus | Principal LifeTime Hybrid 2045 Fund [Member] | Principal LifeTime Hybrid 2045 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHTYX
PFI Prospectus | Principal LifeTime Hybrid 2045 Fund [Member] | Principal LifeTime Hybrid 2045 Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLNTX
PFI Prospectus | Principal LifeTime Hybrid 2050 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Hybrid 2050
PFI Prospectus | Principal LifeTime Hybrid 2050 Fund [Member] | Principal LifeTime Hybrid 2050 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHJUX
PFI Prospectus | Principal LifeTime Hybrid 2050 Fund [Member] | Principal LifeTime Hybrid 2050 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHTUX
PFI Prospectus | Principal LifeTime Hybrid 2050 Fund [Member] | Principal LifeTime Hybrid 2050 Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLJTX
PFI Prospectus | Principal LifeTime Hybrid 2055 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Hybrid 2055
PFI Prospectus | Principal LifeTime Hybrid 2055 Fund [Member] | Principal LifeTime Hybrid 2055 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHJBX
PFI Prospectus | Principal LifeTime Hybrid 2055 Fund [Member] | Principal LifeTime Hybrid 2055 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLTNX
PFI Prospectus | Principal LifeTime Hybrid 2055 Fund [Member] | Principal LifeTime Hybrid 2055 Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLHTX
PFI Prospectus | Principal LifeTime Hybrid 2060 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Hybrid 2060
PFI Prospectus | Principal LifeTime Hybrid 2060 Fund [Member] | Principal LifeTime Hybrid 2060 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHJGX
PFI Prospectus | Principal LifeTime Hybrid 2060 Fund [Member] | Principal LifeTime Hybrid 2060 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLTHX
PFI Prospectus | Principal LifeTime Hybrid 2060 Fund [Member] | Principal LifeTime Hybrid 2060 Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLKTX
PFI Prospectus | Principal LifeTime Hybrid 2065 Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Principal LifeTime Hybrid 2065
PFI Prospectus | Principal LifeTime Hybrid 2065 Fund [Member] | Principal LifeTime Hybrid 2065 Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PHJDX
PFI Prospectus | Principal LifeTime Hybrid 2065 Fund [Member] | Principal LifeTime Hybrid 2065 Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLHHX
PFI Prospectus | Principal LifeTime Hybrid 2065 Fund [Member] | Principal LifeTime Hybrid 2065 Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLHRX
PFI Prospectus | Real Estate Securities Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Real Estate Securities
PFI Prospectus | Real Estate Securities Fund [Member] | Real Estate Securities Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PRRAX
PFI Prospectus | Real Estate Securities Fund [Member] | Real Estate Securities Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PRCEX
PFI Prospectus | Real Estate Securities Fund [Member] | Real Estate Securities Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PREJX
PFI Prospectus | Real Estate Securities Fund [Member] | Real Estate Securities Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIREX
PFI Prospectus | Real Estate Securities Fund [Member] | Real Estate Securities Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PRAEX
PFI Prospectus | Real Estate Securities Fund [Member] | Real Estate Securities Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PRERX
PFI Prospectus | Real Estate Securities Fund [Member] | Real Estate Securities Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PRETX
PFI Prospectus | Real Estate Securities Fund [Member] | Real Estate Securities Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PREPX
PFI Prospectus | Real Estate Securities Fund [Member] | Real Estate Securities Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PFRSX
PFI Prospectus | Strategic Asset Management Balanced Portfolio [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading SAM Balanced
PFI Prospectus | Strategic Asset Management Balanced Portfolio [Member] | SAM Balanced Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SABPX
PFI Prospectus | Strategic Asset Management Balanced Portfolio [Member] | SAM Balanced Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SCBPX
PFI Prospectus | Strategic Asset Management Balanced Portfolio [Member] | SAM Balanced Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSAJX
PFI Prospectus | Strategic Asset Management Balanced Portfolio [Member] | SAM Balanced Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSBIX
PFI Prospectus | Strategic Asset Management Balanced Portfolio [Member] | SAM Balanced Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSBGX
PFI Prospectus | Strategic Asset Management Balanced Portfolio [Member] | SAM Balanced Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PBAPX
PFI Prospectus | Strategic Asset Management Balanced Portfolio [Member] | SAM Balanced Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSBLX
PFI Prospectus | Strategic Asset Management Balanced Portfolio [Member] | SAM Balanced Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSBFX
PFI Prospectus | Strategic Asset Management Conservative Balanced Portfolio [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading SAM Conservative Balanced
PFI Prospectus | Strategic Asset Management Conservative Balanced Portfolio [Member] | SAM Conservative Balanced Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SAIPX
PFI Prospectus | Strategic Asset Management Conservative Balanced Portfolio [Member] | SAM Conservative Balanced Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SCIPX
PFI Prospectus | Strategic Asset Management Conservative Balanced Portfolio [Member] | SAM Conservative Balanced Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCBJX
PFI Prospectus | Strategic Asset Management Conservative Balanced Portfolio [Member] | SAM Conservative Balanced Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCCIX
PFI Prospectus | Strategic Asset Management Conservative Balanced Portfolio [Member] | SAM Conservative Balanced Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCSSX
PFI Prospectus | Strategic Asset Management Conservative Balanced Portfolio [Member] | SAM Conservative Balanced Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCBPX
PFI Prospectus | Strategic Asset Management Conservative Balanced Portfolio [Member] | SAM Conservative Balanced Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCBLX
PFI Prospectus | Strategic Asset Management Conservative Balanced Portfolio [Member] | SAM Conservative Balanced Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCBFX
PFI Prospectus | Strategic Asset Management Conservative Growth Portfolio [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading SAM Conservative Growth
PFI Prospectus | Strategic Asset Management Conservative Growth Portfolio [Member] | SAM Conservative Growth Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SAGPX
PFI Prospectus | Strategic Asset Management Conservative Growth Portfolio [Member] | SAM Conservative Growth Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SCGPX
PFI Prospectus | Strategic Asset Management Conservative Growth Portfolio [Member] | SAM Conservative Growth Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCGJX
PFI Prospectus | Strategic Asset Management Conservative Growth Portfolio [Member] | SAM Conservative Growth Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCWIX
PFI Prospectus | Strategic Asset Management Conservative Growth Portfolio [Member] | SAM Conservative Growth Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCGGX
PFI Prospectus | Strategic Asset Management Conservative Growth Portfolio [Member] | SAM Conservative Growth Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCGPX
PFI Prospectus | Strategic Asset Management Conservative Growth Portfolio [Member] | SAM Conservative Growth Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCWSX
PFI Prospectus | Strategic Asset Management Conservative Growth Portfolio [Member] | SAM Conservative Growth Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCWPX
PFI Prospectus | Strategic Asset Management Flexible Income Portfolio [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading SAM Flexible Income
PFI Prospectus | Strategic Asset Management Flexible Income Portfolio [Member] | SAM Flexible Income Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SAUPX
PFI Prospectus | Strategic Asset Management Flexible Income Portfolio [Member] | SAM Flexible Income Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SCUPX
PFI Prospectus | Strategic Asset Management Flexible Income Portfolio [Member] | SAM Flexible Income Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PFIJX
PFI Prospectus | Strategic Asset Management Flexible Income Portfolio [Member] | SAM Flexible Income Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PIFIX
PFI Prospectus | Strategic Asset Management Flexible Income Portfolio [Member] | SAM Flexible Income Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PFIGX
PFI Prospectus | Strategic Asset Management Flexible Income Portfolio [Member] | SAM Flexible Income Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PFIPX
PFI Prospectus | Strategic Asset Management Flexible Income Portfolio [Member] | SAM Flexible Income Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PFILX
PFI Prospectus | Strategic Asset Management Flexible Income Portfolio [Member] | SAM Flexible Income Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PFIFX
PFI Prospectus | Strategic Asset Management Strategic Growth Portfolio [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading SAM Strategic Growth
PFI Prospectus | Strategic Asset Management Strategic Growth Portfolio [Member] | SAM Strategic Growth Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SACAX
PFI Prospectus | Strategic Asset Management Strategic Growth Portfolio [Member] | SAM Strategic Growth Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SWHCX
PFI Prospectus | Strategic Asset Management Strategic Growth Portfolio [Member] | SAM Strategic Growth Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSWJX
PFI Prospectus | Strategic Asset Management Strategic Growth Portfolio [Member] | SAM Strategic Growth Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSWIX
PFI Prospectus | Strategic Asset Management Strategic Growth Portfolio [Member] | SAM Strategic Growth Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSGGX
PFI Prospectus | Strategic Asset Management Strategic Growth Portfolio [Member] | SAM Strategic Growth Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSGPX
PFI Prospectus | Strategic Asset Management Strategic Growth Portfolio [Member] | SAM Strategic Growth Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSGLX
PFI Prospectus | Strategic Asset Management Strategic Growth Portfolio [Member] | SAM Strategic Growth Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSGFX
PFI Prospectus | Short-Term Income Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Short-Term Income
PFI Prospectus | Short-Term Income Fund [Member] | Short-Term Income Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol SRHQX
PFI Prospectus | Short-Term Income Fund [Member] | Short-Term Income Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol STCCX
PFI Prospectus | Short-Term Income Fund [Member] | Short-Term Income Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSJIX
PFI Prospectus | Short-Term Income Fund [Member] | Short-Term Income Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSHIX
PFI Prospectus | Short-Term Income Fund [Member] | Short-Term Income Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSIMX
PFI Prospectus | Short-Term Income Fund [Member] | Short-Term Income Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSIOX
PFI Prospectus | Short-Term Income Fund [Member] | Short-Term Income Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSIPX
PFI Prospectus | Short-Term Income Fund [Member] | Short-Term Income Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSIQX
PFI Prospectus | SmallCap Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading SmallCap
PFI Prospectus | SmallCap Fund [Member] | SmallCap Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PLLAX
PFI Prospectus | SmallCap Fund [Member] | SmallCap Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSMCX
PFI Prospectus | SmallCap Fund [Member] | SmallCap Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSBJX
PFI Prospectus | SmallCap Fund [Member] | SmallCap Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSLIX
PFI Prospectus | SmallCap Fund [Member] | SmallCap Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSABX
PFI Prospectus | SmallCap Fund [Member] | SmallCap Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSBMX
PFI Prospectus | SmallCap Fund [Member] | SmallCap Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSBSX
PFI Prospectus | SmallCap Fund [Member] | SmallCap Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSBPX
PFI Prospectus | SmallCap Fund [Member] | SmallCap Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSMLX
PFI Prospectus | SmallCap Growth Fund I [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading SmallCap Growth I
PFI Prospectus | SmallCap Growth Fund I [Member] | SmallCap Growth Fund I, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSIJX
PFI Prospectus | SmallCap Growth Fund I [Member] | SmallCap Growth Fund I, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PGRTX
PFI Prospectus | SmallCap Growth Fund I [Member] | SmallCap Growth Fund I, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PNASX
PFI Prospectus | SmallCap Growth Fund I [Member] | SmallCap Growth Fund I, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPNMX
PFI Prospectus | SmallCap Growth Fund I [Member] | SmallCap Growth Fund I, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPNSX
PFI Prospectus | SmallCap Growth Fund I [Member] | SmallCap Growth Fund I, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PPNPX
PFI Prospectus | SmallCap Growth Fund I [Member] | SmallCap Growth Fund I, Class R-6 Shares [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PCSMX
PFI Prospectus | SmallCap S&P 600 Index Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading SmallCap S&P 600 Index
PFI Prospectus | SmallCap S&P 600 Index Fund [Member] | SmallCap S&P 600 Index Fund, Class J [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSSJX
PFI Prospectus | SmallCap S&P 600 Index Fund [Member] | SmallCap S&P 600 Index Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSSIX
PFI Prospectus | SmallCap S&P 600 Index Fund [Member] | SmallCap S&P 600 Index Fund, Class R-1 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSAPX
PFI Prospectus | SmallCap S&P 600 Index Fund [Member] | SmallCap S&P 600 Index Fund, Class R-3 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSSMX
PFI Prospectus | SmallCap S&P 600 Index Fund [Member] | SmallCap S&P 600 Index Fund, Class R-4 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSSSX
PFI Prospectus | SmallCap S&P 600 Index Fund [Member] | SmallCap S&P 600 Index Fund, Class R-5 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSSPX
PFI Prospectus | SmallCap S&P 600 Index Fund [Member] | SmallCap S&P 600 Index Fund, Class R-6 [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PSPIX
PFI Prospectus | Tax-Exempt Bond Fund [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Tax-Exempt Bond
PFI Prospectus | Tax-Exempt Bond Fund [Member] | Tax-Exempt Bond Fund, Class A [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTEAX
PFI Prospectus | Tax-Exempt Bond Fund [Member] | Tax-Exempt Bond Fund, Class C [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PTBCX
PFI Prospectus | Tax-Exempt Bond Fund [Member] | Tax-Exempt Bond Fund, Institutional Class [Member]  
Risk/Return: rr_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol PITEX