Investments - Appreciation (Depreciation) on Fixed Maturities (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 16,598	$ 15,273
Unrealized Appreciation	1,745	1,312
Unrealized (Depreciation)	(22)	(99)
Total Fair Value	18,321	16,486
Run-off Settlement Annuity Business [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized Appreciation	692	478
Unrealized (Depreciation)	(2)	(20)
Total Fair Value	2,900	2,600
Federal government and agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	914	640
Unrealized Appreciation	338	242
Unrealized (Depreciation)	0	(2)
Total Fair Value	1,252	880
State and local government [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,838	1,983
Unrealized Appreciation	188	167
Unrealized (Depreciation)	(3)	(6)
Total Fair Value	2,023	2,144
Foreign government [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,620	1,392
Unrealized Appreciation	91	64
Unrealized (Depreciation)	(5)	(12)
Total Fair Value	1,706	1,444
Corporate [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,389	10,306
Unrealized Appreciation	1,020	749
Unrealized (Depreciation)	(12)	(74)
Total Fair Value	12,397	10,981
Federal agency mortgage-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	68	77
Unrealized Appreciation	1	0
Unrealized (Depreciation)	0	(1)
Total Fair Value	69	76
Other mortgage-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	76	76
Unrealized Appreciation	4	3
Unrealized (Depreciation)	(2)	(2)
Total Fair Value	78	77
Other asset-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	693	799
Unrealized Appreciation	103	87
Unrealized (Depreciation)	0	(2)
Total Fair Value	$ 796	$ 884