Insurance (Guarantees) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	$ 8,198	$ 6,852	$ 5,490
Incurred guaranteed benefits	1,024	1,403	1,422
Paid guaranteed benefits	(56)	(57)	(60)
Balance at December 31,	9,166	8,198	6,852
Variable Annuity Guarantees | Guaranteed Minimum Death Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	1,416	1,106	831
Incurred guaranteed benefits	183	367	335
Paid guaranteed benefits	(56)	(57)	(60)
Balance at December 31,	1,543	1,416	1,106
Variable Annuity Guarantees | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	2,550	2,206	1,872
Incurred guaranteed benefits	358	344	334
Paid guaranteed benefits	0	0	0
Balance at December 31,	2,908	2,550	2,206
Universal and Variable Life Contracts | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	4,232	3,540	2,787
Incurred guaranteed benefits	483	692	753
Paid guaranteed benefits	0	0	0
Balance at December 31,	4,715	4,232	3,540
Net Ceded/(Assumed)
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	902	893	1,041	$ 945
liabilities for guarantees on long duration contracts reinsurance recoverable incurred benefits net	63	(93)	151
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	(54)	(55)	(55)
Net Ceded/(Assumed) | Secondary Guarantees
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	964	946	1,105	1,007
liabilities for guarantees on long duration contracts reinsurance recoverable incurred benefits net	18	(159)	98
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	0	0	0
Net Ceded/(Assumed) | Guaranteed Minimum Death Benefit
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	(12)	(6)	(45)	(34)
liabilities for guarantees on long duration contracts reinsurance recoverable incurred benefits net	48	94	44
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	(54)	(55)	(55)
Net Ceded/(Assumed) | Guaranteed Minimum Income Benefit
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	(50)	(47)	(19)	(28)
liabilities for guarantees on long duration contracts reinsurance recoverable incurred benefits net	(3)	(28)	9
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	0	0	0
Net
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	8,264	7,305	5,811	4,545
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	961	1,496	1,271
Paid guaranteed benefits	(2)	(2)	(5)
Net | Secondary Guarantees
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	3,751	3,286	2,435	1,780
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	465	851	655
Paid guaranteed benefits	0	0	0
Net | Guaranteed Minimum Death Benefit
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	1,555	1,422	1,151	865
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	135	273	291
Paid guaranteed benefits	(2)	(2)	(5)
Net | Guaranteed Minimum Income Benefit
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	2,958	2,597	2,225	$ 1,900
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	361	372	325
Paid guaranteed benefits	$ 0	$ 0	$ 0