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Label Element Value
Prospectus: rr_ProspectusTable  
Document Type dei_DocumentType 497
Document Period End Date dei_DocumentPeriodEndDate Aug. 31, 2016
Entity Registrant Name dei_EntityRegistrantName PRINCIPAL FUNDS INC
Central Index Key dei_EntityCentralIndexKey 0000898745
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Jun. 16, 2017
Document Effective Date dei_DocumentEffectiveDate Jun. 16, 2017
Prospectus Date rr_ProspectusDate Jun. 16, 2017
Supplement [Text Block] ck0000898745_SupplementTextBlock
Principal Funds, Inc.

Supplement dated June 16, 2017
to the Statutory Prospectus dated April 7, 2017, as revised on May 2, 2017

This supplement updates information currently in the Statutory Prospectus. Please retain this supplement for future reference.

Principal Funds Inc | Global Multi-Strategy Fund [Member]  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading GLOBAL MULTI-STRATEGY FUND
Performance Table Heading rr_PerformanceTableHeading In the Performance section, delete the last row of the Average Annual Total Returns table and replace with the following:
Principal Funds Inc | Global Multi-Strategy Fund [Member] | HFRI (Hedge Fund Research Inc.) Funds-of-Funds Composite Index [Member]  
Prospectus: rr_ProspectusTable  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
Label rr_AverageAnnualReturnLabel HFRI (Hedge Fund Research Inc.) Fund-of-Funds Composite Index (reflects no deduction for fees, expenses, or taxes)
1 Year rr_AverageAnnualReturnYear01 0.51%
5 Years rr_AverageAnnualReturnYear05 3.42%
10 Years rr_AverageAnnualReturnYear10 3.20%