Investments (Fixed Maturity Securities AFS by Sector) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 60,226	$ 59,672
Gross Unrealized Gains	5,999	3,025
Gross Unrealized Temporary Losses	218	1,352
Gross Unrealized OTTI Losses	(4)	(3)
Debt Securities, Available-for-sale	66,011	61,348
U.S. corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	25,634	23,902
Gross Unrealized Gains	2,190	816
Gross Unrealized Temporary Losses	86	659
Gross Unrealized OTTI Losses	0	0
Debt Securities, Available-for-sale	27,738	24,059
U.S. government and agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,318	7,503
Gross Unrealized Gains	1,742	1,251
Gross Unrealized Temporary Losses	0	110
Gross Unrealized OTTI Losses	0	0
Debt Securities, Available-for-sale	7,060	8,644
RMBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,883	8,309
Gross Unrealized Gains	425	246
Gross Unrealized Temporary Losses	18	122
Gross Unrealized OTTI Losses	(4)	(2)
Debt Securities, Available-for-sale	9,294	8,435
Foreign corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,981	8,044
Gross Unrealized Gains	532	157
Gross Unrealized Temporary Losses	97	306
Gross Unrealized OTTI Losses	0	0
Debt Securities, Available-for-sale	9,416	7,895
CMBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,932	5,177
Gross Unrealized Gains	249	42
Gross Unrealized Temporary Losses	4	87
Gross Unrealized OTTI Losses	0	(1)
Debt Securities, Available-for-sale	5,177	5,133
State and political subdivision
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,192	3,202
Gross Unrealized Gains	634	399
Gross Unrealized Temporary Losses	1	15
Gross Unrealized OTTI Losses	0	0
Debt Securities, Available-for-sale	3,825	3,586
ABS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,827	2,120
Gross Unrealized Gains	24	13
Gross Unrealized Temporary Losses	9	22
Gross Unrealized OTTI Losses	0	0
Debt Securities, Available-for-sale	1,842	2,111
Foreign government
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,459	1,415
Gross Unrealized Gains	203	101
Gross Unrealized Temporary Losses	3	31
Gross Unrealized OTTI Losses	0	0
Debt Securities, Available-for-sale	$ 1,659	$ 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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