Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 6.0
Maximum length of time hedged in cash flow hedge	40 years
Credit Protection Purchased Notional Amounts	$ 1.0	$ 2.0
Credit Derivative Protection Purchased Fair Value Asset (Liability)	0.0	(0.1)
Future Policy Benefits
Derivative [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset (Liability), Net	(4,191.0)	(5,453.0)
Reinsurance Recoverables
Derivative [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset (Liability), Net	4,198.0	5,458.0
Reinsurance Recoverables \| PALAC and Prudential Insurance
Derivative [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset (Liability), Net	4,214.0	5,445.0
Reinsurance Recoverables \| Union Hamilton Reinsurance, Ltd.
Derivative [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset (Liability), Net	(16.0)	13.0
Policyholders' account balances
Derivative [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset (Liability), Net	$ (40.0)	$ (47.0)

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

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- Definition

Maximum potential amount of future undiscounted payments that could be required under the credit derivative, before reduction for potential recoveries under recourse or collateralization provisions.

+ References

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- Definition

Fair value of credit risk derivative asset after deduction of credit risk derivative liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4K
-Subparagraph (c)
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Reference 2: 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.

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- Definition

Net fair value as of the balance sheet date of the embedded derivative or group of embedded derivatives classified as assets, net of those classified as liabilities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

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- Definition

Maximum length of time over which the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
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