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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Assets
Balance at beginning of period	$ 851	$ 677	$ 832	$ 738
Total gains (losses) included in: net income	9	16	27	(15)
Total gains (losses) included in: OCI	3	(13)	0	(15)
Transfers into Level 3	0	69	13	80
Transfers out of Level 3	(55)	(65)	(33)	(99)
Transfers to (from) held for sale	0		0
Purchases	36	112	91	140
Sales	(75)	(21)	(122)	(22)
Issues	0	0	0	0
Settlements	(42)	(1)	(81)	(33)
Balance at end of period	727	774	727	774
Liabilities
Balance at the beginning of the period	(463)	(417)	(516)	(462)
Total gains (losses) included in: net income	(24)	(69)	31	(21)
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Transfers to (from) held for sale	0		0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	(8)	(7)	(16)	(15)
Settlements	5	5	11	10
Balance at the end of the period	(490)	(488)	(490)	(488)
Net investment income
Total Level 3 gains (losses) included in net income
Gain (loss) included in earnings	(5)	0	(6)	(14)
Realized capital gains (losses)
Total Level 3 gains (losses) included in net income
Gain (loss) included in earnings	13	7	32	2
Liabilities held for sale
Liabilities
Balance at the beginning of the period	(463)	(417)	(516)	(462)
Total gains (losses) included in: net income	(24)	(69)	31	(21)
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Transfers to (from) held for sale	0		0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	(8)	(7)	(16)	(15)
Settlements	5	5	11	10
Balance at the end of the period	(490)	(488)	(490)	(488)
Municipal
Assets
Balance at beginning of period	18	19	17	22
Total gains (losses) included in: net income	0	0	0	0
Total gains (losses) included in: OCI	0	0	1	(1)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Transfers to (from) held for sale	0		0
Purchases	0	7	3	7
Sales	0	0	0	(1)
Issues	0	0	0	0
Settlements	0	0	(3)	(1)
Balance at end of period	18	26	18	26
Corporate - public
Assets
Balance at beginning of period	43	36	67	36
Total gains (losses) included in: net income	0	0	0	0
Total gains (losses) included in: OCI	1	(8)	(2)	(8)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(3)	0	0	0
Transfers to (from) held for sale	0		(6)
Purchases	0	15	14	15
Sales	(21)	0	(53)	0
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	20	43	20	43
Corporate - privately placed
Assets
Balance at beginning of period	105	33	63	32
Total gains (losses) included in: net income	0	0	1	0
Total gains (losses) included in: OCI	2	0	0	(1)
Transfers into Level 3	0	0	10	0
Transfers out of Level 3	(27)	0	0	0
Transfers to (from) held for sale	1		14
Purchases	23	21	16	23
Sales	(20)	(2)	(20)	(2)
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	84	52	84	52
ABS
Assets
Balance at beginning of period	79	32	52	49
Total gains (losses) included in: net income	0	2	0	0
Total gains (losses) included in: OCI	0	(2)	0	(2)
Transfers into Level 3	0	43	0	55
Transfers out of Level 3	(25)	(25)	(32)	(49)
Transfers to (from) held for sale	0		0
Purchases	0	5	34	19
Sales	(4)	(10)	(4)	0
Issues	0	0	0	0
Settlements	(40)	0	(40)	(27)
Balance at end of period	10	45	10	45
MBS
Assets
Balance at beginning of period	23	35	27	35
Total gains (losses) included in: net income	0	0	0	0
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Transfers to (from) held for sale	0		0
Purchases	0	10	0	10
Sales	0	(1)	(4)	(1)
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	23	44	23	44
Fixed income securities
Assets
Balance at beginning of period	268	155	226	174
Total gains (losses) included in: net income	0	2	1	0
Total gains (losses) included in: OCI	3	(10)	(1)	(12)
Transfers into Level 3	0	43	10	55
Transfers out of Level 3	(55)	(25)	(32)	(49)
Transfers to (from) held for sale	1		8
Purchases	23	58	67	74
Sales	(45)	(13)	(81)	(4)
Issues	0	0	0	0
Settlements	(40)	0	(43)	(28)
Balance at end of period	155	210	155	210
Equity securities
Assets
Balance at beginning of period	410	239	304	255
Total gains (losses) included in: net income	8	5	25	(12)
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Transfers to (from) held for sale	8		100
Purchases	6	29	10	30
Sales	(27)	0	(34)	0
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	405	273	405	273
Short-term investments
Assets
Balance at beginning of period	0	50	35	25
Total gains (losses) included in: net income	0	0	0	0
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	(40)	0	(25)
Transfers to (from) held for sale	0		0
Purchases	0	0	0	10
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	0	0	(35)	0
Balance at end of period	0	10	0	10
Other investments
Assets
Balance at beginning of period	3		0
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		0
Purchases	0		3
Sales	0		0
Issues	0		0
Settlements	0		0
Balance at end of period	3		3
Assets held for sale
Assets
Balance at beginning of period	170	233	267	284
Total gains (losses) included in: net income	1	9	1	(3)
Total gains (losses) included in: OCI	0	(3)	1	(3)
Transfers into Level 3	0	26	3	25
Transfers out of Level 3	0	0	(1)	(25)
Transfers to (from) held for sale	(9)		(108)
Purchases	7	25	11	26
Sales	(3)	(8)	(7)	(18)
Issues	0	0	0	0
Settlements	(2)	(1)	(3)	(5)
Balance at end of period	$ 164	$ 281	$ 164	$ 281