Investments - Investments - ACL on Fixed Maturities (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	$ 4	$ 32	$ 23	$ 0
Credit losses on fixed maturities where credit losses were not previously recorded	0	3	2	38
Reduction due to sales	0	(1)	(15)	(3)
Net increases (decreases) in allowance on fixed maturities that had an allowance in a previous period	0	(2)	(6)	(3)
Debt Securities, Available-for-sale, Allowance for Credit Loss, Ending Balance	4	32	4	32
Corporate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	4	32	23	0
Credit losses on fixed maturities where credit losses were not previously recorded	0	0	2	35
Reduction due to sales	0	(1)	(15)	(3)
Net increases (decreases) in allowance on fixed maturities that had an allowance in a previous period	0	(2)	(6)	(3)
Debt Securities, Available-for-sale, Allowance for Credit Loss, Ending Balance	4	29	4	29
Municipal
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance		0	0	0
Credit losses on fixed maturities where credit losses were not previously recorded		3		3
Reduction due to sales		0		0
Net increases (decreases) in allowance on fixed maturities that had an allowance in a previous period		0		0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Ending Balance	$ 0	$ 3	$ 0	$ 3

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=124269663&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=124269663&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=123581744&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=124258926&loc=SL82898722-210454

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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.

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Amount of expense (reversal of expense) for 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), not intended to be sold and not more likely than not will be required to sell before recovery of amortized cost basis, with previously recorded allowance.

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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.

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