Investments - Appreciation (Depreciation) on Fixed Maturities (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 17,171	$ 15,273
Unrealized Appreciation	1,662	1,312
Unrealized (Depreciation)	(36)	(99)
Total Fair Value	18,797	16,486
Run-off Settlement Annuity Business [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized Appreciation	687	478
Unrealized (Depreciation)	(3)	(20)
Total Fair Value	3,100	2,600
Federal government and agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	911	640
Unrealized Appreciation	331	242
Unrealized (Depreciation)	0	(2)
Total Fair Value	1,242	880
State and local government [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,768	1,983
Unrealized Appreciation	182	167
Unrealized (Depreciation)	(2)	(6)
Total Fair Value	1,948	2,144
Foreign government [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,759	1,392
Unrealized Appreciation	106	64
Unrealized (Depreciation)	(8)	(12)
Total Fair Value	1,857	1,444
Corporate [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,029	10,306
Unrealized Appreciation	945	749
Unrealized (Depreciation)	(25)	(74)
Total Fair Value	12,949	10,981
Federal agency mortgage-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12	77
Unrealized Appreciation	0	0
Unrealized (Depreciation)	0	(1)
Total Fair Value	12	76
Other mortgage-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	72	76
Unrealized Appreciation	3	3
Unrealized (Depreciation)	(1)	(2)
Total Fair Value	74	77
Other asset-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	620	799
Unrealized Appreciation	95	87
Unrealized (Depreciation)	0	(2)
Total Fair Value	$ 715	$ 884