Insurance (Liabilities for Guarantees) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	$ 5,548	$ 5,127	$ 4,783
Incurred guaranteed benefits	1,063	485	403
Paid guaranteed benefits	(170)	(64)	(59)
Balance at December 31,	6,441	5,548	5,127
Variable Annuity Guarantees: | Guaranteed Minimum Death and Withdrawal Benefit [Member]
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	465	428	528
Incurred guaranteed benefits	195	62	(78)
Paid guaranteed benefits	(21)	(25)	(22)
Balance at December 31,	639	465	428
Variable Annuity Guarantees: | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	894	898	720
Incurred guaranteed benefits	240	(3)	178
Paid guaranteed benefits	(5)	(1)	0
Balance at December 31,	1,129	894	898
Universal and Variable Life Contracts | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	3,762	3,442	3,188
Incurred guaranteed benefits	602	358	291
Paid guaranteed benefits	(99)	(38)	(37)
Balance at December 31,	4,265	3,762	3,442
Universal and Variable Life Contracts | Secondary Guarantees | Foreign Currency Translation
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	125	23	62
Universal and Variable Life Contracts | Paid-Up Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	427	359	347
Incurred guaranteed benefits	26	68	12
Paid guaranteed benefits	(45)	0	0
Balance at December 31,	408	427	359
Ceded
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	640	530	523
Incurred guaranteed benefits	125	106	3
Paid guaranteed benefits	(41)	4	4
Balance at December 31,	724	640	530
Ceded | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	349	269	241
Incurred guaranteed benefits	96	80	28
Paid guaranteed benefits	(18)	0	0
Balance at December 31,	427	349	269
Ceded | Paid-Up Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	281	251	242
Incurred guaranteed benefits	43	30	9
Paid guaranteed benefits	(32)	0	0
Balance at December 31,	292	281	251
Ceded | Guaranteed Minimum Death and Withdrawal Benefit [Member]
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	0	0	34
Incurred guaranteed benefits	(11)	(4)	(38)
Paid guaranteed benefits	9	4	4
Balance at December 31,	(2)	0	0
Ceded | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	10	10	6
Incurred guaranteed benefits	(3)	0	4
Paid guaranteed benefits	0	0	0
Balance at December 31,	7	10	10
Net
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	4,908	4,597	4,260
Incurred guaranteed benefits	938	379	400
Paid guaranteed benefits	(129)	(68)	(63)
Balance at December 31,	5,717	4,908	4,597
Net | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	3,413	3,173	2,947
Incurred guaranteed benefits	506	278	263
Paid guaranteed benefits	(81)	(38)	(37)
Balance at December 31,	3,838	3,413	3,173
Net | Paid-Up Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	146	108	105
Incurred guaranteed benefits	(17)	38	3
Paid guaranteed benefits	(13)	0	0
Balance at December 31,	116	146	108
Net | Guaranteed Minimum Death and Withdrawal Benefit [Member]
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	465	428	494
Incurred guaranteed benefits	206	66	(40)
Paid guaranteed benefits	(30)	(29)	(26)
Balance at December 31,	641	465	428
Net | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	884	888	714
Incurred guaranteed benefits	243	(3)	174
Paid guaranteed benefits	(5)	(1)	0
Balance at December 31,	$ 1,122	$ 884	$ 888