Investments - Appreciation (Depreciation) on Fixed Maturities (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 17,466	$ 17,278
Unrealized Appreciation	1,420	1,747
Unrealized (Depreciation)	(139)	(42)
Total Fair Value	18,747	18,983
Run-off Settlement Annuity Business [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized Appreciation	614	758
Unrealized (Depreciation)	(22)	(2)
Total Fair Value	2,800	3,100
Federal government and agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	553	608
Unrealized Appreciation	308	346
Unrealized (Depreciation)	0	0
Total Fair Value	861	954
State and local government [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,569	1,682
Unrealized Appreciation	151	176
Unrealized (Depreciation)	(3)	(2)
Total Fair Value	1,717	1,856
Foreign government [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,815	1,824
Unrealized Appreciation	140	121
Unrealized (Depreciation)	(5)	(5)
Total Fair Value	1,950	1,940
Corporate [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,978	12,517
Unrealized Appreciation	772	1,014
Unrealized (Depreciation)	(126)	(33)
Total Fair Value	13,624	13,498
Mortgage-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	54	83
Unrealized Appreciation	2	3
Unrealized (Depreciation)	(1)	(1)
Total Fair Value	55	85
Other asset-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	497	564
Unrealized Appreciation	47	87
Unrealized (Depreciation)	(4)	(1)
Total Fair Value	$ 540	$ 650