Investments (Continuous Gross Unrealized Losses for Fixed Maturity Securities by Sector) (Details) $ in Millions	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities in continuous unrealized loss position, less than 12 months, estimated fair value	$ 5,838	$ 4,419
Fixed maturity securities in continuous unrealized loss position, less than 12 months, gross unrealized losses	$ 281	$ 74
Fixed maturity securities in continuous unrealized loss position, less than 12 months, number of securities	1,319	686
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, estimated fair value	$ 1,505	$ 2,031
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, gross unrealized losses	$ 165	$ 92
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, number of securities	261	297
U.S. Corporate
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities in continuous unrealized loss position, less than 12 months, estimated fair value	$ 2,723	$ 1,931
Fixed maturity securities in continuous unrealized loss position, less than 12 months, gross unrealized losses	150	43
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, estimated fair value	285	320
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, gross unrealized losses	51	22
Foreign Corporate
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities in continuous unrealized loss position, less than 12 months, estimated fair value	1,248	577
Fixed maturity securities in continuous unrealized loss position, less than 12 months, gross unrealized losses	69	12
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, estimated fair value	542	510
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, gross unrealized losses	88	55
RMBS
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities in continuous unrealized loss position, less than 12 months, estimated fair value	291	802
Fixed maturity securities in continuous unrealized loss position, less than 12 months, gross unrealized losses	12	6
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, estimated fair value	22	346
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, gross unrealized losses	1	4
U.S. Government and Agency
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities in continuous unrealized loss position, less than 12 months, estimated fair value	0	14
Fixed maturity securities in continuous unrealized loss position, less than 12 months, gross unrealized losses	0	0
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, estimated fair value	0	0
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, gross unrealized losses	0	0
CMBS
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities in continuous unrealized loss position, less than 12 months, estimated fair value	566	552
Fixed maturity securities in continuous unrealized loss position, less than 12 months, gross unrealized losses	20	7
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, estimated fair value	90	171
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, gross unrealized losses	2	2
State and Political Subdivision
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities in continuous unrealized loss position, less than 12 months, estimated fair value	26	120
Fixed maturity securities in continuous unrealized loss position, less than 12 months, gross unrealized losses	0	2
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, estimated fair value	0	8
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, gross unrealized losses	0	0
ABS
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities in continuous unrealized loss position, less than 12 months, estimated fair value	853	358
Fixed maturity securities in continuous unrealized loss position, less than 12 months, gross unrealized losses	23	2
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, estimated fair value	563	676
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, gross unrealized losses	23	9
Foreign Government
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities in continuous unrealized loss position, less than 12 months, estimated fair value	131	65
Fixed maturity securities in continuous unrealized loss position, less than 12 months, gross unrealized losses	7	2
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, estimated fair value	3	0
Fixed maturity securities in continuous unrealized loss position, 12 months or greater, gross unrealized losses	$ 0	$ 0

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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