Insurance (Guarantees) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	$ 10,261	$ 9,166	$ 8,198
Incurred guaranteed benefits	2,461	1,184	1,024
Paid guaranteed benefits	(272)	(89)	(56)
Balance at December 31,	12,450	10,261	9,166
Variable Annuity Guarantees | Guaranteed Minimum Death Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	1,596	1,543	1,416
Incurred guaranteed benefits	128	142	183
Paid guaranteed benefits	(103)	(89)	(56)
Balance at December 31,	1,621	1,596	1,543
Variable Annuity Guarantees | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	3,076	2,908	2,550
Incurred guaranteed benefits	1,089	168	358
Paid guaranteed benefits	0	0	0
Balance at December 31,	4,165	3,076	2,908
Universal and Variable Life Contracts | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	5,589	4,715	4,232
Incurred guaranteed benefits	1,244	874	483
Paid guaranteed benefits	(169)	0	0
Balance at December 31,	6,664	5,589	4,715
Net Ceded and Assumed Liabilities For Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	(140)	(87)	(54)
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	1,053	1,017	902	$ 893
Liabilities for Guarantees on long duration contracts reinsurance recoverable incurred benefits net	176	202	63
Net Ceded and Assumed Liabilities For Guarantees | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	(39)	0	0
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	1,146	1,083	964	946
Liabilities for Guarantees on long duration contracts reinsurance recoverable incurred benefits net	102	119	18
Net Ceded and Assumed Liabilities For Guarantees | Guaranteed Minimum Death Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	(101)	(87)	(54)
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	(21)	(15)	(12)	(6)
Liabilities for Guarantees on long duration contracts reinsurance recoverable incurred benefits net	95	84	48
Net Ceded and Assumed Liabilities For Guarantees | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	0	0	0
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	(72)	(51)	(50)	(47)
Liabilities for Guarantees on long duration contracts reinsurance recoverable incurred benefits net	(21)	(1)	(3)
Net Liabilities For Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	2,285	982	961
Paid guaranteed benefits	(132)	(2)	(2)
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	11,397	9,244	8,264	7,305
Net Liabilities For Guarantees | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	1,142	755	465
Paid guaranteed benefits	(130)	0	0
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	5,518	4,506	3,751	3,286
Net Liabilities For Guarantees | Guaranteed Minimum Death Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	33	58	135
Paid guaranteed benefits	(2)	(2)	(2)
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	1,642	1,611	1,555	1,422
Net Liabilities For Guarantees | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	1,110	169	361
Paid guaranteed benefits	0	0	0
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	$ 4,237	$ 3,127	$ 2,958	$ 2,597