Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	$ 2,426	$ 980
OCI before reclassifications	475	1,076
Deferred income tax benefit (expense)	(165)	(376)
OCI before reclassifications, net of income tax	2,736	1,680
Amounts reclassified from AOCI	(24)	(27)
Deferred income tax benefit (expense)	8	9
Amounts reclassified from AOCI, net of income tax	(16)	(18)
Balance, end of period	2,720	1,662
Unrealized Investment Gains (Losses), Net of Related Offsets
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	2,250	916
OCI before reclassifications	393	1,000
Deferred income tax benefit (expense)	(138)	(337)
OCI before reclassifications, net of income tax	2,505	1,579
Amounts reclassified from AOCI	(26)	(27)
Deferred income tax benefit (expense)	9	9
Amounts reclassified from AOCI, net of income tax	(17)	(18)
Balance, end of period	2,488	1,561
Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	183	25
OCI before reclassifications	92	65
Deferred income tax benefit (expense)	(31)	(23)
OCI before reclassifications, net of income tax	244	67
Amounts reclassified from AOCI	2	0
Deferred income tax benefit (expense)	(1)	0
Amounts reclassified from AOCI, net of income tax	1	0
Balance, end of period	245	67
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(7)	39
OCI before reclassifications	(10)	11
Deferred income tax benefit (expense)	4	(16)
OCI before reclassifications, net of income tax	(13)	34
Amounts reclassified from AOCI	0	0
Deferred income tax benefit (expense)	0	0
Amounts reclassified from AOCI, net of income tax	0	0
Balance, end of period	$ (13)	$ 34