XML 9 R2.htm IDEA: XBRL DOCUMENT v3.8.0.1
Label Element Value
Prospectus: rr_ProspectusTable  
Supplement [Text Block] ck0000898745_SupplementTextBlock
Principal Funds, Inc.
Supplement dated January 8, 2018
to the Statutory Prospectus dated December 31, 2017
 
This supplement updates information currently in the Statutory Prospectus. Please retain this supplement for future reference.
Document Type dei_DocumentType 497
Document Period End Date dei_DocumentPeriodEndDate Dec. 31, 2017
Entity Registrant Name dei_EntityRegistrantName PRINCIPAL FUNDS INC
Central Index Key dei_EntityCentralIndexKey 0000898745
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Jan. 08, 2018
Document Effective Date dei_DocumentEffectiveDate Jan. 08, 2018
Prospectus Date rr_ProspectusDate Jan. 08, 2018
Principal Funds Inc | SystematEx International Fund  
Prospectus: rr_ProspectusTable  
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Lowest return for a quarter during the period of the bar chart above:    Q1 '16    (2.80)%
Principal Funds Inc | SystematEx International Fund | Institutional Class  
Prospectus: rr_ProspectusTable  
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest return for a quarter during the period of the bar chart above:
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2016
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (2.80%)