Fair Value of Assets and Liabilities - Rollforward of level 3 assets and liabilities held at fair value (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Assets
Balance at beginning of period	$ 832	$ 738	$ 697
Total gains (losses) included in: net income	128	0	31
Total gains (losses) included in: OCI	2	(12)	7
Transfers into Level 3	32	128	61
Transfers out of Level 3	(45)	(116)	(32)
Transfers to (from) held for sale	0
Purchases	124	240	156
Sales	(405)	(95)	(146)
Issues	0	0	0
Settlements	(103)	(51)	(36)
Balance at end of period	565	832	738
Liabilities
Balance at beginning of period	(516)	(462)	(224)
Total gains (losses) included in: net income	35	(43)	(61)
Total gains (losses) included in: OCI	0	0	0
Transfers into Level 3	0	0	(175)
Transfers out of Level 3	0	0	0
Transfers to (from) held for sale	0
Purchases	0	0	0
Sales	492	0	0
Issues	(28)	(34)	(16)
Settlements	17	23	14
Balance at end of period	0	(516)	(462)
Net investment income
Fair value assets and liabilities measured on recurring basis, gain (loss) included in earnings
Gain (loss) included in earnings	1	(16)	0
Net gains (losses) on investments and derivatives
Fair value assets and liabilities measured on recurring basis, gain (loss) included in earnings
Gain (loss) included in earnings	124	15	16
Liabilities held for sale
Liabilities
Balance at beginning of period	(516)	(462)	(224)
Total gains (losses) included in: net income	35	(43)	(61)
Total gains (losses) included in: OCI	0	0	0
Transfers into Level 3	0	0	(175)
Transfers out of Level 3	0	0	0
Transfers to (from) held for sale	0
Purchases	0	0	0
Sales	492	0	0
Issues	(28)	(34)	(16)
Settlements	17	23	14
Balance at end of period	0	(516)	(462)
Municipal
Assets
Balance at beginning of period	17	22	31
Total gains (losses) included in: net income	0	0	0
Total gains (losses) included in: OCI	0	0	1
Transfers into Level 3	1	0	0
Transfers out of Level 3	0	0	(6)
Transfers to (from) held for sale	0
Purchases	3	0	0
Sales	0	(3)	(3)
Issues	0	0	0
Settlements	(3)	(2)	(1)
Balance at end of period	18	17	22
Corporate - public
Assets
Balance at beginning of period	67	36	38
Total gains (losses) included in: net income	1	0	0
Total gains (losses) included in: OCI	(1)	1	2
Transfers into Level 3	0	1	0
Transfers out of Level 3	0	0	0
Transfers to (from) held for sale	(7)
Purchases	13	48	0
Sales	(53)	(19)	(4)
Issues	0	0	0
Settlements	0	0	0
Balance at end of period	20	67	36
Corporate - privately placed
Assets
Balance at beginning of period	63	32	32
Total gains (losses) included in: net income	(2)	0	0
Total gains (losses) included in: OCI	3	(5)	0
Transfers into Level 3	10	21	2
Transfers out of Level 3	0	0	0
Transfers to (from) held for sale	14
Purchases	6	17	1
Sales	(23)	(2)	(2)
Issues	0	0	0
Settlements	(5)	0	(1)
Balance at end of period	66	63	32
ABS
Assets
Balance at beginning of period	79	84	73
Total gains (losses) included in: net income	0	(1)	0
Total gains (losses) included in: OCI	1	0	0
Transfers into Level 3	4	54	2
Transfers out of Level 3	(32)	(49)	(21)
Transfers to (from) held for sale	0
Purchases	47	59	33
Sales	(5)	(26)	0
Issues	0	0	0
Settlements	(54)	(42)	(3)
Balance at end of period	40	79	84
Fixed income securities
Assets
Balance at beginning of period	226	174	174
Total gains (losses) included in: net income	(1)	(1)	0
Total gains (losses) included in: OCI	3	(4)	3
Transfers into Level 3	15	76	4
Transfers out of Level 3	(32)	(49)	(27)
Transfers to (from) held for sale	7
Purchases	69	124	34
Sales	(81)	(50)	(9)
Issues	0	0	0
Settlements	(62)	(44)	(5)
Balance at end of period	144	226	174
Equity securities
Assets
Balance at beginning of period	304	255	212
Total gains (losses) included in: net income	61	0	16
Total gains (losses) included in: OCI	0	0	0
Transfers into Level 3	0	0	0
Transfers out of Level 3	0	0	(1)
Transfers to (from) held for sale	101
Purchases	43	57	73
Sales	(160)	(8)	(44)
Issues	0	0	0
Settlements	0	0	(1)
Balance at end of period	349	304	255
Short-term investments
Assets
Balance at beginning of period	35	25	30
Total gains (losses) included in: net income	0	0	0
Total gains (losses) included in: OCI	0	0	0
Transfers into Level 3	0	0	0
Transfers out of Level 3	0	(25)	0
Transfers to (from) held for sale	0
Purchases	5	35	35
Sales	0	0	(40)
Issues	0	0	0
Settlements	(35)	0	0
Balance at end of period	5	35	25
Other investments
Assets
Balance at beginning of period	0	0	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
Purchases	3		0
Sales	(1)		0
Issues	0		0
Settlements	0		0
Balance at end of period	2	0	0
Other assets
Assets
Balance at beginning of period	0
Total gains (losses) included in: net income	65
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	0
Sales	0
Issues	0
Settlements	0
Balance at end of period	65	0
Assets held for sale
Assets
Balance at beginning of period	267	284	281
Total gains (losses) included in: net income	3	1	15
Total gains (losses) included in: OCI	(1)	(8)	4
Transfers into Level 3	17	52	57
Transfers out of Level 3	(13)	(42)	(4)
Transfers to (from) held for sale	(108)
Purchases	4	24	14
Sales	(163)	(37)	(53)
Issues	0	0	0
Settlements	(6)	(7)	(30)
Balance at end of period	$ 0	$ 267	$ 284

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