Insurance (Liabilities for Guarantees) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	$ 5,127	$ 4,783	$ 4,372
Incurred guaranteed benefits	485	403	461
Paid guaranteed benefits	(64)	(59)	(50)
Balance at December 31,	5,548	5,127	4,783
Variable Annuity Guarantees: | Guaranteed Minimum Death and Withdrawal Benefit [Member]
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	428	528	451
Incurred guaranteed benefits	62	(78)	91
Paid guaranteed benefits	(25)	(22)	(14)
Balance at December 31,	465	428	528
Variable Annuity Guarantees: | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	898	720	601
Incurred guaranteed benefits	(3)	178	121
Paid guaranteed benefits	(1)	0	(2)
Balance at December 31,	894	898	720
Universal and Variable Life Contracts | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	3,442	3,188	2,989
Incurred guaranteed benefits	358	291	233
Paid guaranteed benefits	(38)	(37)	(34)
Balance at December 31,	3,762	3,442	3,188
Universal and Variable Life Contracts | Secondary Guarantees | Foreign Currency Translation
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	23	62	78
Universal and Variable Life Contracts | Paid-Up Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	359	347	331
Incurred guaranteed benefits	68	12	16
Paid guaranteed benefits	0	0	0
Balance at December 31,	427	359	347
Ceded
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	530	523	451
Incurred guaranteed benefits	106	3	66
Paid guaranteed benefits	4	4	6
Balance at December 31,	640	530	523
Ceded | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	269	241	191
Incurred guaranteed benefits	80	28	50
Paid guaranteed benefits	0	0	0
Balance at December 31,	349	269	241
Ceded | Paid-Up Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	251	242	231
Incurred guaranteed benefits	30	9	11
Paid guaranteed benefits	0	0	0
Balance at December 31,	281	251	242
Ceded | Guaranteed Minimum Death and Withdrawal Benefit [Member]
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	0	34	24
Incurred guaranteed benefits	(4)	(38)	4
Paid guaranteed benefits	4	4	6
Balance at December 31,	0	0	34
Ceded | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	10	6	5
Incurred guaranteed benefits	0	4	1
Paid guaranteed benefits	0	0	0
Balance at December 31,	10	10	6
Net
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	4,597	4,260	3,921
Incurred guaranteed benefits	379	400	395
Paid guaranteed benefits	(68)	(63)	(56)
Balance at December 31,	4,908	4,597	4,260
Net | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	3,173	2,947	2,798
Incurred guaranteed benefits	278	263	183
Paid guaranteed benefits	(38)	(37)	(34)
Balance at December 31,	3,413	3,173	2,947
Net | Paid-Up Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	108	105	100
Incurred guaranteed benefits	38	3	5
Paid guaranteed benefits	0	0	0
Balance at December 31,	146	108	105
Net | Guaranteed Minimum Death and Withdrawal Benefit [Member]
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	428	494	427
Incurred guaranteed benefits	66	(40)	87
Paid guaranteed benefits	(29)	(26)	(20)
Balance at December 31,	465	428	494
Net | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	888	714	596
Incurred guaranteed benefits	(3)	174	120
Paid guaranteed benefits	(1)	0	(2)
Balance at December 31,	$ 884	$ 888	$ 714