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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Assets
Balance at beginning of period	$ 727	$ 774	$ 832	$ 738
Total gains (losses) included in: net income	33	2	68	(14)
Total gains (losses) included in: OCI	0	10	0	(5)
Transfers into Level 3	1	20	13	83
Transfers out of Level 3	(42)	(75)	(45)	(116)
Transfers to (from) held for sale	0		0
Purchases	150	186	236	267
Sales	(95)	(47)	(265)	(52)
Issues	0	0	0	0
Settlements	(37)	(15)	(102)	(46)
Balance at end of period	737	855	737	855
Liabilities
Balance at the beginning of the period	(490)	(488)	(516)	(462)
Total gains (losses) included in: net income	15	(6)	46	(27)
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	(9)	(10)	(25)	(25)
Settlements	5	7	16	17
Balance at the end of the period	(479)	(497)	(479)	(497)
Net investment income
Total Level 3 gains (losses) included in net income
Gain (loss) included in earnings	6	(1)	(1)	(15)
Realized capital gains (losses)
Total Level 3 gains (losses) included in net income
Gain (loss) included in earnings	26	1	66	2
Liabilities held for sale
Liabilities
Balance at the beginning of the period	(490)	(488)	(516)	(462)
Total gains (losses) included in: net income	15	(6)	46	(27)
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	(9)	(10)	(25)	(25)
Settlements	5	7	16	17
Balance at the end of the period	(479)	(497)	(479)	(497)
Municipal
Assets
Balance at beginning of period	18	26	17	22
Total gains (losses) included in: net income	0	0	0	0
Total gains (losses) included in: OCI	(1)	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	(7)	0	0
Transfers to (from) held for sale	0		0
Purchases	0	0	3	0
Sales	0	(2)	0	(3)
Issues	0	0	0	0
Settlements	0	0	(3)	(2)
Balance at end of period	17	17	17	17
Corporate - public
Assets
Balance at beginning of period	20	43	67	36
Total gains (losses) included in: net income	0	0	1	(1)
Total gains (losses) included in: OCI	0	9	(2)	1
Transfers into Level 3	0	0	0	1
Transfers out of Level 3	0	0	0	0
Transfers to (from) held for sale	(1)		(7)
Purchases	0	59	13	64
Sales	0	(10)	(53)	0
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	19	101	19	101
Corporate - privately placed
Assets
Balance at beginning of period	84	52	63	32
Total gains (losses) included in: net income	1	0	0	0
Total gains (losses) included in: OCI	1	0	2	0
Transfers into Level 3	0	0	8	0
Transfers out of Level 3	(22)	(19)	0	0
Transfers to (from) held for sale	(2)		14
Purchases	104	34	103	35
Sales	(7)	(2)	(31)	(2)
Issues	0	0	0	0
Settlements	(5)	0	(5)	0
Balance at end of period	154	65	154	65
ABS
Assets
Balance at beginning of period	10	45	52	49
Total gains (losses) included in: net income	0	(1)	1	(1)
Total gains (losses) included in: OCI	0	1	0	(1)
Transfers into Level 3	1	0	0	51
Transfers out of Level 3	0	(2)	(32)	(49)
Transfers to (from) held for sale	0		0
Purchases	5	17	57	33
Sales	0	(23)	(37)	(19)
Issues	0	0	0	0
Settlements	(15)	0	(40)	(26)
Balance at end of period	1	37	1	37
MBS
Assets
Balance at beginning of period	23	44	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	0	0	10
Sales	0	0	(5)	(1)
Issues	0	0	0	0
Settlements	(15)	(15)	(14)	(15)
Balance at end of period	8	29	8	29
Fixed income securities
Assets
Balance at beginning of period	155	210	226	174
Total gains (losses) included in: net income	1	(1)	2	(2)
Total gains (losses) included in: OCI	0	10	0	0
Transfers into Level 3	1	0	8	52
Transfers out of Level 3	(22)	(28)	(32)	(49)
Transfers to (from) held for sale	(3)		7
Purchases	109	110	176	142
Sales	(7)	(37)	(126)	(25)
Issues	0	0	0	0
Settlements	(35)	(15)	(62)	(43)
Balance at end of period	199	249	199	249
Equity securities
Assets
Balance at beginning of period	405	273	304	255
Total gains (losses) included in: net income	31	0	63	(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	(1)	0	0
Transfers to (from) held for sale	0		101
Purchases	27	4	40	33
Sales	(87)	(5)	(132)	(5)
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	376	271	376	271
Short-term investments
Assets
Balance at beginning of period	0	10	35	25
Total gains (losses) included in: net income	0	1	0	1
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	(25)
Transfers to (from) held for sale	0		0
Purchases	14	19	14	29
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	0	0	(35)	0
Balance at end of period	14	30	14	30
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	(1)		(1)
Issues	0		0
Settlements	0		0
Balance at end of period	2		2
Assets held for sale
Assets
Balance at beginning of period	164	281	267	284
Total gains (losses) included in: net income	1	2	3	(1)
Total gains (losses) included in: OCI	0	0	0	(5)
Transfers into Level 3	0	20	5	31
Transfers out of Level 3	(20)	(46)	(13)	(42)
Transfers to (from) held for sale	3		(108)
Purchases	0	53	3	63
Sales	0	(5)	(6)	(22)
Issues	0	0	0	0
Settlements	(2)	0	(5)	(3)
Balance at end of period	$ 146	$ 305	$ 146	$ 305