Insurance (Guarantees) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	$ 9,166	$ 8,198	$ 6,852
Incurred guaranteed benefits	1,184	1,024	1,403
Paid guaranteed benefits	(89)	(56)	(57)
Balance at December 31,	10,261	9,166	8,198
Variable Annuity Guarantees | Guaranteed Minimum Death Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	1,543	1,416	1,106
Incurred guaranteed benefits	142	183	367
Paid guaranteed benefits	(89)	(56)	(57)
Balance at December 31,	1,596	1,543	1,416
Variable Annuity Guarantees | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	2,908	2,550	2,206
Incurred guaranteed benefits	168	358	344
Paid guaranteed benefits	0	0	0
Balance at December 31,	3,076	2,908	2,550
Universal and Variable Life Contracts | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	4,715	4,232	3,540
Incurred guaranteed benefits	874	483	692
Paid guaranteed benefits	0	0	0
Balance at December 31,	5,589	4,715	4,232
Net Ceded and Assumed Liabilities For Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	(87)	(54)	(55)
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	1,017	902	893	$ 1,041
Liabilities for Guarantees on long duration contracts reinsurance recoverable incurred benefits net	202	63	(93)
Net Ceded and Assumed Liabilities For Guarantees | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	0	0	0
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	1,083	964	946	1,105
Liabilities for Guarantees on long duration contracts reinsurance recoverable incurred benefits net	119	18	(159)
Net Ceded and Assumed Liabilities For Guarantees | Guaranteed Minimum Death Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	(87)	(54)	(55)
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	(15)	(12)	(6)	(45)
Liabilities for Guarantees on long duration contracts reinsurance recoverable incurred benefits net	84	48	94
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	(51)	(50)	(47)	(19)
Liabilities for Guarantees on long duration contracts reinsurance recoverable incurred benefits net	(1)	(3)	(28)
Net Liabilities For Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	982	961	1,496
Paid guaranteed benefits	(2)	(2)	(2)
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	9,244	8,264	7,305	5,811
Net Liabilities For Guarantees | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	755	465	851
Paid guaranteed benefits	0	0	0
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	4,506	3,751	3,286	2,435
Net Liabilities For Guarantees | Guaranteed Minimum Death Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	58	135	273
Paid guaranteed benefits	(2)	(2)	(2)
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	1,611	1,555	1,422	1,151
Net Liabilities For Guarantees | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	169	361	372
Paid guaranteed benefits	0	0	0
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	$ 3,127	$ 2,958	$ 2,597	$ 2,225