Label	Element	Value
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Document Type	dei_DocumentType	497
Document Period End Date	dei_DocumentPeriodEndDate	Oct. 31, 2019
Entity Registrant Name	dei_EntityRegistrantName	PRINCIPAL FUNDS INC
Central Index Key	dei_EntityCentralIndexKey	0000898745
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Jul. 17, 2020
Document Effective Date	dei_DocumentEffectiveDate	Jul. 17, 2020
Prospectus Date	rr_ProspectusDate	Mar. 01, 2020
PFI Prospectus \| Government & High Quality Bond Fund [Member]
Prospectus:	rr_ProspectusTable
Supplement [Text Block]	ck0000898745_SupplementTextBlock	Principal Funds, Inc. Supplement dated July 17, 2020 to the Statutory Prospectus dated March 1, 2020 (as previously supplemented) This supplement updates information currently in the Statutory Prospectus. Please retain this supplement for future reference.
Risk/Return [Heading]	rr_RiskReturnHeading	SUMMARY FOR GOVERNMENT & HIGH QUALITY BOND FUND
Strategy [Heading]	rr_StrategyHeading	Delete the second paragraph under Principal Investment Strategies, and replace with the following paragraph:
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal circumstances, the Fund maintains an average portfolio duration that is within ±50% of the duration of the Bloomberg Barclays Fixed-Rate MBS Index, which as of December 31, 2019 was 3.21 years. The Fund is not managed to a particular maturity.

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Prospectus:

rr_ProspectusTable

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497

Document Period End Date

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Oct. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

PRINCIPAL FUNDS INC

Central Index Key

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0000898745

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false

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dei_DocumentCreationDate

Jul. 17, 2020

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Jul. 17, 2020

Prospectus Date

rr_ProspectusDate

Mar. 01, 2020

PFI Prospectus | Government & High Quality Bond Fund [Member]

Prospectus:

rr_ProspectusTable

Supplement [Text Block]

ck0000898745_SupplementTextBlock

Principal Funds, Inc.

Supplement dated July 17, 2020

to the Statutory Prospectus dated March 1, 2020

(as previously supplemented)

This supplement updates information currently in the Statutory Prospectus. Please retain this supplement for future reference.

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY FOR GOVERNMENT & HIGH QUALITY BOND FUND

Strategy [Heading]

rr_StrategyHeading

Delete the second paragraph under Principal Investment Strategies, and replace with the following paragraph:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal circumstances, the Fund maintains an average portfolio duration that is within ±50% of the duration of the Bloomberg Barclays Fixed-Rate MBS Index, which as of December 31, 2019 was 3.21 years. The Fund is not managed to a particular maturity.

- Definition

Supplement [Text Block]

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The date the document was made available and submitted, in CCYY-MM-DD format. The date of submission, date of acceptance by the recipient, and the document effective date are all potentially different.

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The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.

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- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word "Other".

+ References

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- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12b
-Subsection 1

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-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12b
-Subsection 1

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- Definition

The date of the prospectus.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 1
-Subsection a
-Paragraph 3

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Prospectus Table.

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-Publisher SEC
-Name Form
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-Chapter A

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Risk/Return Summary Investment Objectives/Goals Include the following information, in plain English under rule 421(d) under the Securities Act, in the order and subject matter indicated

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 2

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- Definition

Principal investment strategies of the Fund. Summarize how the Fund intends to achieve its investment objectives by identifying the Fund's principal investment strategies (including the type or types of securities in which the Fund invests or will invest principally) and any policy to concentrate in securities of issuers in a particular industry or group of industries.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 4
-Subsection a

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