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,	$ 9,357	$ 8,380	$ 6,999
Incurred guaranteed benefits	1,180	1,035	1,439
Paid guaranteed benefits	(90)	(58)	(58)
Balance at December 31,	10,447	9,357	8,380
Variable Annuity Guarantees | Guaranteed Minimum Death Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	1,567	1,439	1,124
Incurred guaranteed benefits	143	186	373
Paid guaranteed benefits	(90)	(58)	(58)
Balance at December 31,	1,620	1,567	1,439
Variable Annuity Guarantees | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	3,074	2,709	2,335
Incurred guaranteed benefits	163	365	374
Paid guaranteed benefits	0	0	0
Balance at December 31,	3,237	3,074	2,709
Universal and Variable Life Contracts | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	4,716	4,232	3,540
Incurred guaranteed benefits	874	484	692
Paid guaranteed benefits	0	0	0
Balance at December 31,	5,590	4,716	4,232
Net Ceded and Assumed Liabilities For Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	(88)	(56)	(56)
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	1,092	974	963	$ 1,098
Liabilities for Guarantees on Long-Duration contracts reinsurance recoverable incurred benefits net	206	67	(79)
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	963	945	1,105
Liabilities for Guarantees on Long-Duration contracts reinsurance recoverable incurred benefits net	120	18	(160)
Net Ceded and Assumed Liabilities For Guarantees | Guaranteed Minimum Death Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Paid guaranteed benefits	(88)	(56)	(56)
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	9	11	18	(27)
Liabilities for Guarantees on Long-Duration contracts reinsurance recoverable incurred benefits net	86	49	101
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	0	0	0	20
Liabilities for Guarantees on Long-Duration contracts reinsurance recoverable incurred benefits net	0	0	(20)
Net Liabilities For Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	974	968	1,518
Paid guaranteed benefits	(2)	(2)	(2)
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	9,355	8,383	7,417	5,901
Net Liabilities For Guarantees | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	754	466	852
Paid guaranteed benefits	0	0	0
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	4,507	3,753	3,287	2,435
Net Liabilities For Guarantees | Guaranteed Minimum Death Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	57	137	272
Paid guaranteed benefits	(2)	(2)	(2)
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	1,611	1,556	1,421	1,151
Net Liabilities For Guarantees | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	163	365	394
Paid guaranteed benefits	0	0	0
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Net	$ 3,237	$ 3,074	$ 2,709	$ 2,315