Equity (Reclassifications Out of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other net investment gains (losses)	$ (42)	$ 17	$ 51	$ 121
Net derivative gains (losses)	(199)	(98)	(581)	45
Net investment income	678	675	2,132	2,223
Other-than-temporary impairments on fixed maturity securities	(4)	(19)	(9)	(50)
Income (loss) before provision for income tax	138	(193)	900	551
Provision for income tax expense (benefit)	(30)	189	(266)	(38)
Net income (loss)	108	(4)	634	513
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	(33)		21
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Investment Gains (Losses), Net of Related Offsets [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other net investment gains (losses)	(56)		24
Net investment income	3		9
Income (loss) before provision for income tax	(58)		22
Provision for income tax expense (benefit)	22		(7)
Net income (loss)	(36)		15
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Other-than-Temporary Impairment [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other-than-temporary impairments on fixed maturity securities	(5)		(11)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains (Losses) on Derivatives [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before provision for income tax	4		9
Provision for income tax expense (benefit)	(1)		(3)
Net income (loss)	3		6
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains (Losses) on Derivatives [Member] | Interest Rate Swaps [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net derivative gains (losses)	2		1
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains (Losses) on Derivatives [Member] | Interest Rate Forwards [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net derivative gains (losses)	1		7
Net investment income	0		1
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains (Losses) on Derivatives [Member] | Foreign Currency Swaps [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net derivative gains (losses)	$ 1		$ 0