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Label Element Value
Prospectus: rr_ProspectusTable  
Document Type dei_DocumentType Other
Document Period End Date dei_DocumentPeriodEndDate Oct. 31, 2014
Registrant Name dei_EntityRegistrantName PRINCIPAL FUNDS INC
Central Index Key dei_EntityCentralIndexKey 0000898745
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Jul. 06, 2015
Document Effective Date dei_DocumentEffectiveDate Jul. 06, 2015
Prospectus Date rr_ProspectusDate Mar. 01, 2015
Supplement [Text Block] ck0000898745_SupplementTextBlock
Principal Funds, Inc.

Supplement dated July 6, 2015
to the Statutory Prospectus dated March 1, 2015
(as supplemented on March 13, 2015, March 23, 2015, April 27, 2015, and June 12, 2015)

This supplement updates information currently in the Statutory Prospectus. Please retain this supplement for future reference.
Strategic Asset Management Balanced Portfolio [Member]  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading SAM (STRATEGIC ASSET MANAGEMENT) BALANCED PORTFOLIO
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
In the Average Annual Total Returns table, replace the rows for the Russell 3000 Index and Barclays U.S. Aggregate Bond Index with the following:
Caption rr_AverageAnnualReturnCaption For the periods ended December 31, 2014
Strategic Asset Management Balanced Portfolio [Member] | Russell 3000 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 Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)
1 Year rr_AverageAnnualReturnYear01 12.56%
5 Years rr_AverageAnnualReturnYear05 15.63%
10 Years rr_AverageAnnualReturnYear10 7.94%
Strategic Asset Management Balanced Portfolio [Member] | Barclays U.S. Aggregate Bond 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 Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
1 Year rr_AverageAnnualReturnYear01 5.97%
5 Years rr_AverageAnnualReturnYear05 4.45%
10 Years rr_AverageAnnualReturnYear10 4.71%