Investments - Appreciation (Depreciation) on Fixed Maturities (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 17,307	$ 17,278
Unrealized Appreciation	1,368	1,747
Unrealized (Depreciation)	(106)	(42)
Total Fair Value	18,569	18,983
Run-off Settlement Annuity Business [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized Appreciation	576	758
Unrealized (Depreciation)	(18)	(2)
Total Fair Value	2,800	3,100
Federal government and agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	545	608
Unrealized Appreciation	284	346
Unrealized (Depreciation)	0	0
Total Fair Value	829	954
State and local government [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,629	1,682
Unrealized Appreciation	145	176
Unrealized (Depreciation)	(3)	(2)
Total Fair Value	1,771	1,856
Foreign government [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,842	1,824
Unrealized Appreciation	120	121
Unrealized (Depreciation)	(5)	(5)
Total Fair Value	1,957	1,940
Corporate [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,757	12,517
Unrealized Appreciation	773	1,014
Unrealized (Depreciation)	(94)	(33)
Total Fair Value	13,436	13,498
Mortgage-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	56	83
Unrealized Appreciation	2	3
Unrealized (Depreciation)	(1)	(1)
Total Fair Value	57	85
Other asset-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	478	564
Unrealized Appreciation	44	87
Unrealized (Depreciation)	(3)	(1)
Total Fair Value	$ 519	$ 650