Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Document Type	dei_DocumentType	Other
Document Period End Date	dei_DocumentPeriodEndDate	Sep. 20, 2013
Registrant Name	dei_EntityRegistrantName	PRINCIPAL FUNDS INC
Central Index Key	dei_EntityCentralIndexKey	0000898745
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Sep. 20, 2013
Document Effective Date	dei_DocumentEffectiveDate	Sep. 20, 2013
Prospectus Date	rr_ProspectusDate	Mar. 01, 2013
PFI Prospectus - Class A, B, C, P
Risk/Return:	rr_RiskReturnAbstract
Supplement [Text Block]	ck0000898745_SupplementTextBlock	Supplement dated September 20, 2013 to the Classes A, B, C, and P Shares Prospectus for Principal Funds, Inc. dated March 1, 2013 (as supplemented on March 14, 2013, March 28, 2013, April 2, 2013, May 9, 2013, and June 14, 2013) This supplement updates information currently in the Prospectus. Retain this supplement with the Prospectus. FUND SUMMARIES
PFI Prospectus - Class A, B, C, P \| Global Diversified Income Fund [Member]
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Global Diversified Income Fund
Strategy [Heading]	rr_StrategyHeading	On or about November 6, 2013, under the Principal Investment Strategies heading, delete the paragraph that begins “A portion of the Fund's assets is invested in publicly-listed infrastructure companies” and substitute:
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	A portion of the Fund's assets is invested in publicly-listed infrastructure companies (domestic and foreign public utility, energy, and transportation companies). Publicly-listed infrastructure equity securities trade on an exchange and include companies involved to a significant extent in providing products, services or equipment for: transportation (including toll roads, airports, railways, and ports); the generation, transmission or distribution of electricity, gas or water (utilities); or telecommunications activities as well as in companies involved in the discovery, development, production, generation, transmission, refinement, measurement, trading, marketing or distribution of energy.

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Document Type

dei_DocumentType

Other

Document Period End Date

dei_DocumentPeriodEndDate

Sep. 20, 2013

Registrant Name

dei_EntityRegistrantName

PRINCIPAL FUNDS INC

Central Index Key

dei_EntityCentralIndexKey

0000898745

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Sep. 20, 2013

Document Effective Date

dei_DocumentEffectiveDate

Sep. 20, 2013

Prospectus Date

rr_ProspectusDate

Mar. 01, 2013

PFI Prospectus - Class A, B, C, P

Risk/Return:

rr_RiskReturnAbstract

Supplement [Text Block]

ck0000898745_SupplementTextBlock

Supplement dated September 20, 2013

to the Classes A, B, C, and P Shares Prospectus

for Principal Funds, Inc.

dated March 1, 2013

(as supplemented on March 14, 2013, March 28, 2013, April 2, 2013, May 9, 2013, and June 14, 2013)

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

FUND SUMMARIES

PFI Prospectus - Class A, B, C, P | Global Diversified Income Fund [Member]

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Global Diversified Income Fund

Strategy [Heading]

rr_StrategyHeading

On or about November 6, 2013, under the Principal Investment Strategies heading, delete the paragraph that begins “A portion of the Fund's assets is invested in publicly-listed infrastructure companies” and substitute:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

A portion of the Fund's assets is invested in publicly-listed infrastructure companies (domestic and foreign public utility, energy, and transportation companies). Publicly-listed infrastructure equity securities trade on an exchange and include companies involved to a significant extent in providing products, services or equipment for: transportation (including toll roads, airports, railways, and ports); the generation, transmission or distribution of electricity, gas or water (utilities); or telecommunications activities as well as in companies involved in the discovery, development, production, generation, transmission, refinement, measurement, trading, marketing or distribution of energy.