Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Credit Derivative, Purchased Credit Protection	$ 2.0	$ 0.0
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	9.0
Credit Derivative Protection Purchased Fair Value Asset (Liability)	0.0	0.0
Future Policy Benefits
Derivative [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset (Liability), Net	(19,014.0)	(8,530.0)
Reinsurance Recoverables
Derivative [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset (Liability), Net	19,028.0	8,540.0
Policyholders' account balances
Derivative [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset (Liability), Net	$ (1,045.0)	$ (962.0)

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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121549185&loc=d3e80748-113994

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Amount of purchased credit protection expected to cover future payments under the credit risk derivative.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4K
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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4K
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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.

+ References

No definition available.

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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.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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-Section 45
-Paragraph 5
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