Label

Element

Value

Prospectus:

rr_ProspectusTable

Document Type

dei_DocumentType

497

Document Period End Date

dei_DocumentPeriodEndDate

Oct. 31, 2016

Entity Registrant Name

dei_EntityRegistrantName

PRINCIPAL FUNDS INC.

Central Index Key

dei_EntityCentralIndexKey

0000898745

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

May 02, 2017

Document Effective Date

dei_DocumentEffectiveDate

May 02, 2017

Prospectus Date

rr_ProspectusDate

Mar. 01, 2017

Supplement [Text Block]

ck0000898745_SupplementTextBlock

Principal Funds, Inc.

Supplement dated May 2, 2017

to the Statutory Prospectus dated March 1, 2017

(as supplemented on March 17, 2017, March 24, 2017, March 27, 2017 and April 7, 2017)

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

PFI Prospectus [Member] | Global Diversified Income Fund

Prospectus:

rr_ProspectusTable

Risk/Return [Heading]

rr_RiskReturnHeading

GLOBAL DIVERSIFIED INCOME FUND

Operating Expenses Caption [Text]

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Effective June 23, 2017, delete the Annual Fund Operating Expenses footnote, as supplemented on March 24, 2017, and replace with the following:

Expense Footnotes [Text Block]

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Principal Global Investors, LLC ("PGI"), the investment advisor, has contractually agreed to limit the Fund’s expenses by paying, if necessary, expenses normally payable by the Fund, (excluding interest expense, expenses related to fund investments, acquired fund fees and expenses, and other extraordinary expenses) to maintain a total level of operating expenses (expressed as a percent of average net assets on an annualized basis) not to exceed 0.76% for Institutional Class shares. The expense cap has been added to limit the potential increase in "Other Expenses" that otherwise may occur due to an expected decrease in the number of Institutional Class shareholders of the Fund. It is expected that the expense limit will continue through the period ending June 30, 2018; however, Principal Funds, Inc. and PGI, the parties to the agreement, may mutually agree to terminate the expense limit prior to the end of the period.