Equity (Reclassifications Out of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other net investment gains (losses)	$ 18	$ 85	$ 93	$ 104
Net derivative gains (losses)	(495)	582	(382)	143
Net investment income	724	656	1,454	1,548
Other expenses	368	887	776	1,344
Other-than-temporary impairments on fixed maturity securities	(3)	(18)	(5)	(31)
Income (loss) before provision for income tax	67	725	762	744
Provision for income tax expense (benefit)	(6)	(227)	(236)	(227)
Amounts reclassified from AOCI	12		54
Net income (loss)	61	498	526	517
Unrealized Investment Gains (Losses), Net of Related Offsets [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	11		51
Unrealized Gains (Losses) on Derivatives [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	1		3
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	12		54
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)	9		80
Net investment income	3		6
Income (loss) before provision for income tax	13		80
Provision for income tax expense (benefit)	(2)		(29)
Net income (loss)	11		51
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	1		(6)
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	3		5
Provision for income tax expense (benefit)	(2)		(2)
Net income (loss)	1		3
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)	0		(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)	3		6
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)	$ 0		$ (1)