Derivatives (Fair Value Hedges) (Details) - Designated as Hedging Instrument [Member] $ in Millions	Mar. 31, 2019 USD ($)
Fixed maturity securities AFS
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Asset, Discontinued Fair Value Hedge, Cumulative Increase (Decrease)	$ (1)
Debt Instruments, Carrying Amount	2,227
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	(1)
Mortgages [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Debt Instruments, Carrying Amount	1,245
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	(1)
Future policy benefits [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Debt Instruments, Carrying Amount	(5,399)
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	(667)
Policyholder Account Balances [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Debt Instruments, Carrying Amount	(81)
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	$ 0

Debt Instruments, Carrying Amount

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Balance Type:	debit
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- 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

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- Definition

Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk, remaining after discontinued hedge.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

+ Details

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