Investments (Fixed Maturity Securities AFS by Sector) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 62,138	$ 59,672
Gross Unrealized Gains	7,746	3,025
Gross Unrealized Temporary Losses	213	1,352
Gross Unrealized OTTI Losses	(5)	(3)
Fixed maturity securities	69,676	61,348
U.S. corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	27,409	23,902
Gross Unrealized Gains	2,972	816
Gross Unrealized Temporary Losses	74	659
Gross Unrealized OTTI Losses	0	0
Fixed maturity securities	30,307	24,059
U.S. government and agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,387	7,503
Gross Unrealized Gains	2,203	1,251
Gross Unrealized Temporary Losses	0	110
Gross Unrealized OTTI Losses	0	0
Fixed maturity securities	7,590	8,644
RMBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,634	8,309
Gross Unrealized Gains	513	246
Gross Unrealized Temporary Losses	12	122
Gross Unrealized OTTI Losses	(5)	(2)
Fixed maturity securities	9,140	8,435
Foreign corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,922	8,044
Gross Unrealized Gains	675	157
Gross Unrealized Temporary Losses	109	306
Gross Unrealized OTTI Losses	0	0
Fixed maturity securities	9,488	7,895
CMBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,208	5,177
Gross Unrealized Gains	340	42
Gross Unrealized Temporary Losses	3	87
Gross Unrealized OTTI Losses	0	(1)
Fixed maturity securities	5,545	5,133
State and political subdivision
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,205	3,202
Gross Unrealized Gains	765	399
Gross Unrealized Temporary Losses	0	15
Gross Unrealized OTTI Losses	0	0
Fixed maturity securities	3,970	3,586
ABS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,894	2,120
Gross Unrealized Gains	27	13
Gross Unrealized Temporary Losses	10	22
Gross Unrealized OTTI Losses	0	0
Fixed maturity securities	1,911	2,111
Foreign government
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,479	1,415
Gross Unrealized Gains	251	101
Gross Unrealized Temporary Losses	5	31
Gross Unrealized OTTI Losses	0	0
Fixed maturity securities	$ 1,725	$ 1,485

Other-than-temporary impairments on fixed maturity securities transferred to other comprehensive income loss.

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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