Label

Element

Value

Risk/Return:

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Document Type

dei_DocumentType

Other

Document Period End Date

dei_DocumentPeriodEndDate

Mar. 15, 2013

Registrant Name

dei_EntityRegistrantName

PRINCIPAL FUNDS INC

Central Index Key

dei_EntityCentralIndexKey

0000898745

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Mar. 15, 2013

Document Effective Date

dei_DocumentEffectiveDate

Mar. 15, 2013

Prospectus Date

rr_ProspectusDate

Dec. 28, 2012

PFI Prospectus - Institutional Class Shares

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Supplement [Text Block]

ck0000898745_SupplementTextBlock

Supplement dated March 15, 2013

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

for Principal Funds, Inc.

dated December 28, 2012

(as supplemented on February 8, 2013)

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

FUND SUMMARIES

PFI Prospectus - Institutional Class Shares | Global Multi-Strategy Fund

Risk/Return:

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Risk/Return [Heading]

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Global Multi-Strategy Fund

Strategy [Heading]

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On or about April 10, 2013, under the Principal Investment Strategies heading, after the Credit Long/Short and Distressed Credit paragraph, add:

Strategy Narrative [Text Block]

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Emerging Market Long/Short Credit. The emerging markets credit opportunities strategy is designed to benefit from opportunities in emerging market, liquid, high grade, high yield, stressed, distressed and other corporate or sovereign credits. This strategy takes long and short exposure to selected emerging market issuers when factors have been identified which the Fund believes will drive substantial appreciation or depreciation of the particular exposure. The geographical focus of the investment strategy is derived from the dynamics of economic and political developments as well as the specific nature of local jurisdictions in the emerging markets.

PFI Prospectus - Institutional Class Shares | Global Multi-Strategy Fund | Global Multi-Strategy Fund, Institutional Class

Risk/Return:

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Trading Symbol

dei_TradingSymbol

PSMIX