Insurance (Liabilities for Guarantees) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	$ 4,783	$ 4,372	$ 3,920
Incurred guaranteed benefits	403	461	496
Paid guaranteed benefits	(59)	(50)	(44)
Balance at December 31,	5,127	4,783	4,372
Variable Annuity Guarantees: | Guaranteed Minimum Death and Withdrawal Benefit [Member]
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	528	451	364
Incurred guaranteed benefits	(78)	91	102
Paid guaranteed benefits	(22)	(14)	(15)
Balance at December 31,	428	528	451
Variable Annuity Guarantees: | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	720	601	524
Incurred guaranteed benefits	178	121	78
Paid guaranteed benefits	0	(2)	(1)
Balance at December 31,	898	720	601
Universal and Variable Life Contracts | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	3,188	2,989	2,726
Incurred guaranteed benefits	291	233	291
Paid guaranteed benefits	(37)	(34)	(28)
Balance at December 31,	3,442	3,188	2,989
Universal and Variable Life Contracts | Secondary Guarantees | Foreign Currency Translation
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	62	78	119
Universal and Variable Life Contracts | Paid-Up Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	347	331	306
Incurred guaranteed benefits	12	16	25
Paid guaranteed benefits	0	0	0
Balance at December 31,	359	347	331
Ceded
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	523	451	457
Incurred guaranteed benefits	3	66	(11)
Paid guaranteed benefits	4	6	5
Balance at December 31,	530	523	451
Ceded | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	241	191	218
Incurred guaranteed benefits	28	50	(27)
Paid guaranteed benefits	0	0	0
Balance at December 31,	269	241	191
Ceded | Paid-Up Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	242	231	214
Incurred guaranteed benefits	9	11	17
Paid guaranteed benefits	0	0	0
Balance at December 31,	251	242	231
Ceded | Guaranteed Minimum Death and Withdrawal Benefit [Member]
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	34	24	19
Incurred guaranteed benefits	(38)	4	0
Paid guaranteed benefits	4	6	5
Balance at December 31,	0	34	24
Ceded | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	6	5	6
Incurred guaranteed benefits	4	1	(1)
Paid guaranteed benefits	0	0	0
Balance at December 31,	10	6	5
Net
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	4,260	3,921	3,463
Incurred guaranteed benefits	400	395	507
Paid guaranteed benefits	(63)	(56)	(49)
Balance at December 31,	4,597	4,260	3,921
Net | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	2,947	2,798	2,508
Incurred guaranteed benefits	263	183	318
Paid guaranteed benefits	(37)	(34)	(28)
Balance at December 31,	3,173	2,947	2,798
Net | Paid-Up Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	105	100	92
Incurred guaranteed benefits	3	5	8
Paid guaranteed benefits	0	0	0
Balance at December 31,	108	105	100
Net | Guaranteed Minimum Death and Withdrawal Benefit [Member]
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	494	427	345
Incurred guaranteed benefits	(40)	87	102
Paid guaranteed benefits	(26)	(20)	(20)
Balance at December 31,	428	494	427
Net | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	714	596	518
Incurred guaranteed benefits	174	120	79
Paid guaranteed benefits	0	(2)	(1)
Balance at December 31,	$ 888	$ 714	$ 596