Fair Value of Assets and Liabilities - Rollforward of level 3 assets and liabilities held at fair value on a recurring basis during the period (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Assets
Balance at beginning of period	$ 832	$ 738
Total gains (losses) included in: net income	18	(29)
Total gains (losses) included in: OCI	(4)	(2)
Transfers into Level 3	13	26
Transfers out of Level 3	(47)	(74)
Transfers to (from) held for sale	0
Purchases	125	60
Sales	(47)	(11)
Issues	0	0
Settlements	(39)	(31)
Balance at end of period	851	677
Liabilities
Balance at the beginning of the period	(516)	(462)
Total gains (losses) included in: net income	55	48
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Transfers to (from) held for sale	0
Purchases	0	0
Sales	0	0
Issues	(8)	(8)
Settlements	6	5
Balance at the end of the period	(463)	(417)
Net investment income
Total Level 3 gains (losses) included in net income
Gain (loss) included in earnings	(1)	(14)
Realized capital gains (losses)
Total Level 3 gains (losses) included in net income
Gain (loss) included in earnings	18	(3)
Liabilities held for sale
Liabilities
Balance at the beginning of the period	(516)	(462)
Total gains (losses) included in: net income	55	48
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Transfers to (from) held for sale	0
Purchases	0	0
Sales	0	0
Issues	(8)	(8)
Settlements	6	5
Balance at the end of the period	(463)	(417)
Municipal
Assets
Balance at beginning of period	17	22
Total gains (losses) included in: net income	0	0
Total gains (losses) included in: OCI	0	(1)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Transfers to (from) held for sale	0
Purchases	3	0
Sales	0	(1)
Issues	0	0
Settlements	(2)	(1)
Balance at end of period	18	19
Corporate - public
Assets
Balance at beginning of period	67	36
Total gains (losses) included in: net income	1	0
Total gains (losses) included in: OCI	(3)	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Transfers to (from) held for sale	(6)
Purchases	17	0
Sales	(33)	0
Issues	0	0
Settlements	0	0
Balance at end of period	43	36
Corporate - privately placed
Assets
Balance at beginning of period	63	32
Total gains (losses) included in: net income	0	0
Total gains (losses) included in: OCI	(1)	0
Transfers into Level 3	10	0
Transfers out of Level 3	(7)	0
Transfers to (from) held for sale	13
Purchases	27	1
Sales	0	0
Issues	0	0
Settlements	0	0
Balance at end of period	105	33
ABS
Assets
Balance at beginning of period	52	49
Total gains (losses) included in: net income	0	0
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	26
Transfers out of Level 3	(32)	(49)
Transfers to (from) held for sale	0
Purchases	59	33
Sales	0	0
Issues	0	0
Settlements	0	(27)
Balance at end of period	79	32
MBS
Assets
Balance at beginning of period	27	35
Total gains (losses) included in: net income	0	0
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Transfers to (from) held for sale	0
Purchases	0	0
Sales	(4)	0
Issues	0	0
Settlements	0	0
Balance at end of period	23	35
Fixed income securities
Assets
Balance at beginning of period	226	174
Total gains (losses) included in: net income	1	0
Total gains (losses) included in: OCI	(4)	(1)
Transfers into Level 3	10	26
Transfers out of Level 3	(39)	(49)
Transfers to (from) held for sale	7
Purchases	106	34
Sales	(37)	(1)
Issues	0	0
Settlements	(2)	(28)
Balance at end of period	268	155
Equity securities
Assets
Balance at beginning of period	304	255
Total gains (losses) included in: net income	16	(17)
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Transfers to (from) held for sale	92
Purchases	5	1
Sales	(7)	0
Issues	0	0
Settlements	0	0
Balance at end of period	410	239
Short-term investments
Assets
Balance at beginning of period	35	25
Total gains (losses) included in: net income	0	0
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Transfers to (from) held for sale	0
Purchases	0	25
Sales	0	0
Issues	0	0
Settlements	(35)	0
Balance at end of period	0	50
Other investments
Assets
Balance at beginning of period	0
Total gains (losses) included in: net income	0
Total gains (losses) included in: OCI	0
Transfers into Level 3	0
Transfers out of Level 3	0
Transfers to (from) held for sale	0
Purchases	3
Sales	0
Issues	0
Settlements	0
Balance at end of period	3
Assets held for sale
Assets
Balance at beginning of period	267	284
Total gains (losses) included in: net income	1	(12)
Total gains (losses) included in: OCI	0	(1)
Transfers into Level 3	3	0
Transfers out of Level 3	(8)	(25)
Transfers to (from) held for sale	(99)
Purchases	11	0
Sales	(3)	(10)
Issues	0	0
Settlements	(2)	(3)
Balance at end of period	$ 170	$ 233

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Amount of gain (loss) recognized in income from asset and liability measured at fair value on recurring basis using unobservable input (level 3).

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Amount of transfers of financial instrument classified as a liability out of level 3 of the fair value hierarchy.

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Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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