Name:	pfg_ContractHolderFundsLineItems
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Data Type:	xbrli:stringItemType
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Period Type:	duration

The amount of investment contracts without significant fee revenue reconciling to contractholder funds per consolidated statements of financial position.

No definition available.

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Namespace Prefix:	pfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount of other balances reconciling to contractholder funds per consolidated statements of financial position.

No definition available.

Name:	pfg_ContractHolderFundsReconcilingItemsOtherBalances
Namespace Prefix:	pfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Contractholder funds include policyholder account balances related to contracts with significant insurance risk and investment contracts.

No definition available.

Name:	pfg_ContractholderFunds
Namespace Prefix:	pfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount due to policyholder. Includes, but is not limited to, unpaid policy dividend, retrospective refund, and undistributed earnings on participating business. Excludes future policy benefit and claim expense.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-7A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-7A

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 29F
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480046/944-40-55-29F

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(14)(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-7A

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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Namespace Prefix:
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