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Amortized cost as of the balance sheet date of hybrid instruments.

No definition available.

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Data Type:	xbrli:monetaryItemType
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Represents the weighted-average expected life in years for hybrid instruments.

No definition available.

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Namespace Prefix:	pfg_
Data Type:	xbrli:durationItemType
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- References

No definition available.

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Fair value as of the balance sheet date of hybrid instruments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 15
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6437212&loc=d3e50806-113969

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13495-108611

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_HybridInstrumentsLineItems
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