XML 92 R74.htm IDEA: XBRL DOCUMENT
v3.20.1

Fair Value Measurements - Quantitative Information for Level 3 Measurements (Details) - Recurring Fair Value Measurements $ in Millions | Mar. 31, 2020 USD ($) item | Dec. 31, 2019 USD ($) item
--- | --- | ---
Unobservable inputs |  |
Assets measured at fair value | $ | $ 211,567.2 | $ 240,519.2
Liabilities measured at fair value | $ | (803.4) | (530.8)
Fair value hierarchy Level 3 |  |
Unobservable inputs |  |
Assets measured at fair value | $ | 9,365.6 | 9,421.5
Liabilities measured at fair value | $ | (572.7) | (230.5)
Fair value hierarchy Level 3 | Investment and universal life contracts |  |
Unobservable inputs |  |
Liabilities measured at fair value | $ | $ (555.4) | $ (214.2)
Embedded derivative, Valuation technique | us-gaap:ValuationTechniqueDiscountedCashFlowMember | us-gaap:ValuationTechniqueDiscountedCashFlowMember
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long duration interest rate |  |
Unobservable inputs |  |
Embedded derivative, Input | 0.009 |
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long duration interest rate | Minimum |  |
Unobservable inputs |  |
Embedded derivative, Input |  | 0.020
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long duration interest rate | Maximum |  |
Unobservable inputs |  |
Embedded derivative, Input |  | 0.021
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long duration interest rate | Weighted average input |  |
Unobservable inputs |  |
Embedded derivative, Input | 0.009 |
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long-term equity market volatility | Minimum |  |
Unobservable inputs |  |
Embedded derivative, Input | 0.169 | 0.150
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long-term equity market volatility | Maximum |  |
Unobservable inputs |  |
Embedded derivative, Input | 0.317 | 0.269
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long-term equity market volatility | Weighted average input |  |
Unobservable inputs |  |
Embedded derivative, Input | 0.195 |
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Non-performance risk | Minimum |  |
Unobservable inputs |  |
Embedded derivative, Input | 0.021 | 0.002
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Non-performance risk | Maximum |  |
Unobservable inputs |  |
Embedded derivative, Input | 0.030 | 0.013
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Non-performance risk | Weighted average input |  |
Unobservable inputs |  |
Embedded derivative, Input | 0.026 |
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Lapse rate | Minimum |  |
Unobservable inputs |  |
Embedded derivative, Input | 0.000 | 0.000
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Lapse rate | Maximum |  |
Unobservable inputs |  |
Embedded derivative, Input | 0.180 | 0.180
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Lapse rate | Weighted average input |  |
Unobservable inputs |  |
Embedded derivative, Input | 0.063 |
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale |  |
Unobservable inputs |  |
Assets measured at fair value | $ | $ 66.1 | $ 72.5
Fixed maturities, available-for-sale, Valuation technique | us-gaap:ValuationTechniqueDiscountedCashFlowMember | us-gaap:ValuationTechniqueDiscountedCashFlowMember
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Discount rate | Minimum |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.031 | 0.019
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Discount rate | Maximum |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.140 | 0.051
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Discount rate | Weighted average input |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.060 | 0.038
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Illiquidity premium | Minimum |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0 | 0
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Illiquidity premium | Maximum |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.0075 | 0.0410
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Illiquidity premium | Weighted average input |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.0046 | 0.0152
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Comparability adjustment | Minimum |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0 |
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Comparability adjustment | Maximum |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.0031 |
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Comparability adjustment | Weighted average input |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.0007 |
Fair value hierarchy Level 3 | Commercial mortgage-backed securities | Available-for-sale |  |
Unobservable inputs |  |
Assets measured at fair value | $ | $ 14.4 | $ 2.4
Fixed maturities, available-for-sale, Valuation technique | us-gaap:ValuationTechniqueDiscountedCashFlowMember | us-gaap:ValuationTechniqueDiscountedCashFlowMember
Fair value hierarchy Level 3 | Commercial mortgage-backed securities | Available-for-sale | Discounted cash flow | Discount rate |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.023 |
Fair value hierarchy Level 3 | Commercial mortgage-backed securities | Available-for-sale | Discounted cash flow | Discount rate | Weighted average input |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.023 |
Fair value hierarchy Level 3 | Commercial mortgage-backed securities | Available-for-sale | Discounted cash flow | Probability of default |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 1.000 | 1.000
Fair value hierarchy Level 3 | Commercial mortgage-backed securities | Available-for-sale | Discounted cash flow | Probability of default | Weighted average input |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 1.000 | 1.000
Fair value hierarchy Level 3 | Commercial mortgage-backed securities | Available-for-sale | Discounted cash flow | Potential loss severity |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.534 | 0.531
Fair value hierarchy Level 3 | Commercial mortgage-backed securities | Available-for-sale | Discounted cash flow | Potential loss severity | Weighted average input |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.534 | 0.531
Fair value hierarchy Level 3 | Collateralized debt obligations | Available-for-sale |  |
Unobservable inputs |  |
Assets measured at fair value | $ | $ 53.0 | $ 108.7
Fixed maturities, available-for-sale, Valuation technique | us-gaap:ValuationTechniqueDiscountedCashFlowMember | us-gaap:ValuationTechniqueDiscountedCashFlowMember
Fair value hierarchy Level 3 | Collateralized debt obligations | Available-for-sale | Discounted cash flow | Discount rate | Minimum |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.031 | 0.029
Fair value hierarchy Level 3 | Collateralized debt obligations | Available-for-sale | Discounted cash flow | Discount rate | Maximum |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.060 | 0.100
Fair value hierarchy Level 3 | Collateralized debt obligations | Available-for-sale | Discounted cash flow | Discount rate | Weighted average input |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.045 | 0.034
Fair value hierarchy Level 3 | Collateralized debt obligations | Available-for-sale | Discounted cash flow | Probability of default |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 1.000 | 1.000
Fair value hierarchy Level 3 | Collateralized debt obligations | Available-for-sale | Discounted cash flow | Probability of default | Weighted average input |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 1.000 | 1.000
Fair value hierarchy Level 3 | Collateralized debt obligations | Available-for-sale | Discounted cash flow | Potential loss severity |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.452 | 0.230
Fair value hierarchy Level 3 | Collateralized debt obligations | Available-for-sale | Discounted cash flow | Potential loss severity | Weighted average input |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.452 | 0.230
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale |  |
Unobservable inputs |  |
Assets measured at fair value | $ | $ 25.3 | $ 1.2
Fixed maturities, available-for-sale, Valuation technique | us-gaap:ValuationTechniqueDiscountedCashFlowMember | us-gaap:ValuationTechniqueDiscountedCashFlowMember
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Discount rate |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input |  | 0.050
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Discount rate | Minimum |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.042 |
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Discount rate | Maximum |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.050 |
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Discount rate | Weighted average input |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.044 | 0.050
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Illiquidity premium |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.0500 | 0.0500
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Illiquidity premium | Weighted average input |  |
Unobservable inputs |  |
Fixed maturities, available-for-sale, Input | 0.0500 | 0.0500
Fair value hierarchy Level 3 | Other investments |  |
Unobservable inputs |  |
Assets measured at fair value | $ | $ 34.6 | $ 14.8
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Discount rate | Minimum |  |
Unobservable inputs |  |
Other investments, Input |  | 0.250
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Discount rate | Maximum |  |
Unobservable inputs |  |
Other investments, Input |  | 0.300
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Discount rate | Weighted average input |  |
Unobservable inputs |  |
Other investments, Input |  | 0.275
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Terminal earnings before interest, taxes, depreciation and amortization multiple | Minimum |  |
Unobservable inputs |  |
Other investments, Input |  | 3.5
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Terminal earnings before interest, taxes, depreciation and amortization multiple | Maximum |  |
Unobservable inputs |  |
Other investments, Input |  | 4.5
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Terminal earnings before interest, taxes, depreciation and amortization multiple | Weighted average input |  |
Unobservable inputs |  |
Other investments, Input |  | 4.0
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, other investments | Discount rate | Minimum |  |
Unobservable inputs |  |
Other investments, Input | 0.250 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, other investments | Discount rate | Maximum |  |
Unobservable inputs |  |
Other investments, Input | 0.300 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, other investments | Discount rate | Weighted average input |  |
Unobservable inputs |  |
Other investments, Input | 0.275 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, other investments | Terminal earnings before interest, taxes, depreciation and amortization multiple | Minimum |  |
Unobservable inputs |  |
Other investments, Input | 3.8 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, other investments | Terminal earnings before interest, taxes, depreciation and amortization multiple | Maximum |  |
Unobservable inputs |  |
Other investments, Input | 4.7 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, other investments | Terminal earnings before interest, taxes, depreciation and amortization multiple | Weighted average input |  |
Unobservable inputs |  |
Other investments, Input | 4.2 |
Fair value hierarchy Level 3 | Other investments | Market comparables | Revenue multiples | Minimum |  |
Unobservable inputs |  |
Other investments, Input | 0.8 | 0.8
Fair value hierarchy Level 3 | Other investments | Market comparables | Revenue multiples | Maximum |  |
Unobservable inputs |  |
Other investments, Input | 7.0 | 7.0
Fair value hierarchy Level 3 | Other investments | Market comparables | Revenue multiples | Weighted average input |  |
Unobservable inputs |  |
Other investments, Input | 3.8 | 4.1
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, real estate | Discount rate |  |
Unobservable inputs |  |
Other investments, Input | 0.084 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, real estate | Discount rate | Weighted average input |  |
Unobservable inputs |  |
Other investments, Input | 0.084 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, real estate | Terminal capitalization rate |  |
Unobservable inputs |  |
Other investments, Input | 0.053 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, real estate | Terminal capitalization rate | Weighted average input |  |
Unobservable inputs |  |
Other investments, Input | 0.053 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, real estate | Average market rent growth rate |  |
Unobservable inputs |  |
Other investments, Input | 0.026 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, real estate | Average market rent growth rate | Weighted average input |  |
Unobservable inputs |  |
Other investments, Input | 0.026 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, real estate debt | Credit spread rate |  |
Unobservable inputs |  |
Other investments, Input | 0.026 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, real estate debt | Credit spread rate | Weighted average input |  |
Unobservable inputs |  |
Other investments, Input | 0.026 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, real estate debt | Loan to value |  |
Unobservable inputs |  |
Other investments, Input | 0.551 |
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, real estate debt | Loan to value | Weighted average input |  |
Unobservable inputs |  |
Other investments, Input | 0.551 |
Fair value hierarchy Level 3 | Separate account assets |  |
Unobservable inputs |  |
Assets measured at fair value | $ | $ 8,864.5 | $ 8,966.2
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, mortgage loans | Discount rate |  |
Unobservable inputs |  |
Separate account assets, Input | 0.037 | 0.028
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, mortgage loans | Discount rate | Weighted average input |  |
Unobservable inputs |  |
Separate account assets, Input | 0.037 | 0.028
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, mortgage loans | Illiquidity premium |  |
Unobservable inputs |  |
Separate account assets, Input | 0.0060 | 0.0060
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, mortgage loans | Illiquidity premium | Weighted average input |  |
Unobservable inputs |  |
Separate account assets, Input | 0.0060 | 0.0060
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, mortgage loans | Credit spread rate |  |
Unobservable inputs |  |
Separate account assets, Input | 0.0338 | 0.0120
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, mortgage loans | Credit spread rate | Weighted average input |  |
Unobservable inputs |  |
Separate account assets, Input | 0.0338 | 0.0120
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Discount rate | Minimum |  |
Unobservable inputs |  |
Separate account assets, Input | 0.055 | 0.055
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Discount rate | Maximum |  |
Unobservable inputs |  |
Separate account assets, Input | 0.118 | 0.118
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Discount rate | Weighted average input |  |
Unobservable inputs |  |
Separate account assets, Input | 0.066 | 0.067
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Terminal capitalization rate | Minimum |  |
Unobservable inputs |  |
Separate account assets, Input | 0.045 | 0.045
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Terminal capitalization rate | Maximum |  |
Unobservable inputs |  |
Separate account assets, Input | 0.093 | 0.093
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Terminal capitalization rate | Weighted average input |  |
Unobservable inputs |  |
Separate account assets, Input | 0.056 | 0.057
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Average market rent growth rate | Minimum |  |
Unobservable inputs |  |
Separate account assets, Input | 0.020 | 0.020
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Average market rent growth rate | Maximum |  |
Unobservable inputs |  |
Separate account assets, Input | 0.047 | 0.047
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Average market rent growth rate | Weighted average input |  |
Unobservable inputs |  |
Separate account assets, Input | 0.029 | 0.030
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Loan to value | Minimum |  |
Unobservable inputs |  |
Separate account assets, Input | 0.080 | 0.080
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Loan to value | Maximum |  |
Unobservable inputs |  |
Separate account assets, Input | 0.804 | 0.804
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Loan to value | Weighted average input |  |
Unobservable inputs |  |
Separate account assets, Input | 0.465 | 0.459
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Market interest rate | Minimum |  |
Unobservable inputs |  |
Separate account assets, Input | 0.034 | 0.032
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Market interest rate | Maximum |  |
Unobservable inputs |  |
Separate account assets, Input | 0.058 | 0.058
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Market interest rate | Weighted average input |  |
Unobservable inputs |  |
Separate account assets, Input | 0.038 | 0.036

X
- Definition 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. + References No definition available. + Details
Name: | pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems
Namespace Prefix: | pfg_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Value of input used to measure other investments. + References No definition available. + Details
Name: | pfg_OtherInvestmentsMeasurementInput
Namespace Prefix: | pfg_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Value of input used to measure separate account assets. + References No definition available. + Details
Name: | pfg_SeparateAccountAssetsMeasurementInput
Namespace Prefix: | pfg_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_AssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Value of input used to measure investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Indicates valuation technique for measuring investment in debt security at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleValuationTechniqueExtensibleList
Namespace Prefix: | us-gaap_
Data Type: | srt-types:extensibleListItemType
Balance Type: | na
Period Type: | instant

X
- Definition Value of input used to measure embedded derivative liability. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_EmbeddedDerivativeLiabilityMeasurementInput
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Indicates valuation technique for measuring embedded derivative liability. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_EmbeddedDerivativeLiabilityValuationTechniqueExtensibleList
Namespace Prefix: | us-gaap_
Data Type: | srt-types:extensibleListItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByLiabilityClassAxis=pfg_InvestmentAndUniversalLifeContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=us-gaap_ValuationTechniqueDiscountedCashFlowMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=pfg_MeasurementInputLongDurationInterestRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputPriceVolatilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=pfg_MeasurementInputNonPerformanceRiskMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputLapseRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentSecondaryCategorizationAxis=us-gaap_AvailableforsaleSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountForLackOfMarketabilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputComparabilityAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDefaultRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputLossSeverityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_CollateralizedDebtObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_OtherDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=pfg_InvestmentsOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=pfg_TerminalEarningsBeforeInterestTaxesDepreciationAndAmortizationMultipleMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=pfg_ValuationTechniqueDiscountedCashFlowOtherInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=us-gaap_MarketApproachValuationTechniqueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=pfg_RevenueMultiplesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=pfg_DiscountedCashFlowRealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=pfg_MeasurementInputTerminalCapitalizationRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputLongTermRevenueGrowthRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=pfg_DiscountedCashFlowRealEstateDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputCreditSpreadMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=pfg_MeasurementInputLoanToValueRatioMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=pfg_SeparateAccountAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=pfg_DiscountedCashFlowMortgageLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=pfg_MeasurementInputMarketInterestRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |