Investments (Allowance For Credit Loss Rollforward) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Fixed maturity securities, Available-for-sale, Allowance for Credit Loss	$ 7	$ 0
Fixed Maturity Securities [Member]
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Fixed maturity securities, Available-for-sale, Allowance for Credit Loss	7	0
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	65
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold	(18)
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	(40)
Foreign Government Securities [Member] \| Fixed Maturity Securities [Member]
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Fixed maturity securities, Available-for-sale, Allowance for Credit Loss	0	0
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	1
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold	(1)
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	0
Corporate Securities [Member] \| Fixed Maturity Securities [Member]
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Fixed maturity securities, Available-for-sale, Allowance for Credit Loss	7	$ 0
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	64
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold	(17)
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	$ (40)

Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922900-210455

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922900-210455

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454

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- Definition

Amount of expense for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), for which no credit loss was previously recorded.

+ References

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- Definition

Amount of increase (decrease) in allowance for credit loss of 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/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922900-210455

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- Definition

Amount of decrease in allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) from sale.

+ References

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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.

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