Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Document Type

dei_DocumentType

Other

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 18, 2014

Registrant Name

dei_EntityRegistrantName

PRINCIPAL FUNDS INC

Central Index Key

dei_EntityCentralIndexKey

0000898745

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Aug. 18, 2014

Document Effective Date

dei_DocumentEffectiveDate

Aug. 18, 2014

Prospectus Date

rr_ProspectusDate

Dec. 30, 2013

PFI Prospectus - Institutional, R-1, R-2, R-3, R-4, R-5 and S Class Shares [Member]

Risk/Return:

rr_RiskReturnAbstract

Supplement [Text Block]

ck0000898745_SupplementTextBlock

Supplement dated August 18, 2014

to the Classes Institutional, R-1, R-2, R-3, R-4, R-5 and S Shares Prospectus

for Principal Funds, Inc.

dated December 30, 2013

(As supplemented on January 2, 2014, February 7, 2014, March 7, 2014, March 14, 2014, April 28, 2014, and June 16, 2014)

This supplement updates information currently in the Prospectus. Retain this supplement with the Prospectus.

FUND SUMMARIES

PFI Prospectus - Institutional, R-1, R-2, R-3, R-4, R-5 and S Class Shares [Member] | Small-MidCap Dividend Income Fund [Member]

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

SMALL-MIDCAP DIVIDEND INCOME FUND

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

Delete the Objective and substitute:

The Fund primarily seeks to provide a relatively high level of current income and long-term growth of income, and secondarily long-term growth of capital.