Investments - Unrealized Losses on AFS Securities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Amortized Cost
Less Than 12 Months		$ 6,798
12 Months or More		2,040
Total		8,838
Fair Value
Less Than 12 Months		6,739
12 Months or More		1,969
Total		8,708
Unrealized Losses
Less Than 12 Months		(59)
12 Months or More		(71)
Total		(130)
ABS
Amortized Cost
Less Than 12 Months	$ 566	461
12 Months or More	113	30
Total	679	491
Fair Value
Less Than 12 Months	566	460
12 Months or More	112	29
Total	678	489
Unrealized Losses
Less Than 12 Months	0	(1)
12 Months or More	(1)	(1)
Total	(1)	(2)
Collateralized loan obligations (CLOs)
Amortized Cost
Less Than 12 Months	1,358	359
12 Months or More	7	1
Total	1,365	360
Fair Value
Less Than 12 Months	1,338	359
12 Months or More	7	1
Total	1,345	360
Unrealized Losses
Less Than 12 Months	(20)	0
12 Months or More	0	0
Total	(20)	0
CMBS
Amortized Cost
Less Than 12 Months	896	1,178
12 Months or More	1,129	243
Total	2,025	1,421
Fair Value
Less Than 12 Months	882	1,167
12 Months or More	1,079	228
Total	1,961	1,395
Unrealized Losses
Less Than 12 Months	(14)	(11)
12 Months or More	(50)	(15)
Total	(64)	(26)
Corporate
Amortized Cost
Less Than 12 Months	7,174	2,322
12 Months or More	2,541	1,064
Total	9,715	3,386
Fair Value
Less Than 12 Months	6,903	2,302
12 Months or More	2,366	1,028
Total	9,269	3,330
Unrealized Losses
Less Than 12 Months	(271)	(20)
12 Months or More	(175)	(36)
Total	(446)	(56)
Foreign government
Amortized Cost
Less Than 12 Months	407	244
12 Months or More	203	51
Total	610	295
Fair Value
Less Than 12 Months	391	242
12 Months or More	193	49
Total	584	291
Unrealized Losses
Less Than 12 Months	(16)	(2)
12 Months or More	(10)	(2)
Total	(26)	(4)
Municipal
Amortized Cost
Less Than 12 Months	1,643	511
12 Months or More	292	236
Total	1,935	747
Fair Value
Less Than 12 Months	1,613	507
12 Months or More	275	228
Total	1,888	735
Unrealized Losses
Less Than 12 Months	(30)	(4)
12 Months or More	(17)	(8)
Total	(47)	(12)
Residential mortgage-backed securities (RMBS)
Amortized Cost
Less Than 12 Months	1,344	889
12 Months or More	648	137
Total	1,992	1,026
Fair Value
Less Than 12 Months	1,329	887
12 Months or More	628	135
Total	1,957	1,022
Unrealized Losses
Less Than 12 Months	(15)	(2)
12 Months or More	(20)	(2)
Total	(35)	(4)
US Treasury Securities
Amortized Cost
Less Than 12 Months	497	658
12 Months or More	339	254
Total	836	912
Fair Value
Less Than 12 Months	492	652
12 Months or More	329	250
Total	821	902
Unrealized Losses
Less Than 12 Months	(5)	(6)
12 Months or More	(10)	(4)
Total	(15)	(10)
Securities available-for-sale and other
Amortized Cost
Less Than 12 Months		6,622
12 Months or More		2,016
Total		8,638
Fair Value
Less Than 12 Months		6,576
12 Months or More		1,948
Total		8,524
Unrealized Losses
Less Than 12 Months		(46)
12 Months or More		(68)
Total		(114)
Fixed maturities
Amortized Cost
Less Than 12 Months	13,885
12 Months or More	5,272
Total	19,157
Fair Value
Less Than 12 Months	13,514
12 Months or More	4,989
Total	18,503
Unrealized Losses
Less Than 12 Months	(371)
12 Months or More	(283)
Total	$ (654)
Equity Securities [Member]
Amortized Cost
Less Than 12 Months		176
12 Months or More		24
Total		200
Fair Value
Less Than 12 Months		163
12 Months or More		21
Total		184
Unrealized Losses
Less Than 12 Months		(13)
12 Months or More		(3)
Total		$ (16)