Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning of period	$ 2,158	$ 4,008	$ 3,054
OCI before reclassifications	3,476	(2,580)	1,515
Deferred income tax benefit (expense)	(1,205)	883	(528)
OCI before reclassifications, net of income tax	4,429	2,311	4,041
Amounts reclassified from AOCI	932	(235)	(50)
Deferred income tax benefit (expense)	(327)	82	17
Amounts reclassified from AOCI, net of income tax	605	(153)	(33)
Balance end of period	5,034	2,158	4,008
Unrealized Investment Gains (Losses), Net of Related Offsets [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning of period	3,468	5,654	4,028
OCI before reclassifications	4,095	(3,321)	2,406
Deferred income tax benefit (expense)	(1,409)	1,145	(843)
OCI before reclassifications, net of income tax	6,154	3,478	5,591
Amounts reclassified from AOCI	70	(16)	96
Deferred income tax benefit (expense)	(24)	6	(33)
Amounts reclassified from AOCI, net of income tax	46	(10)	63
Balance end of period	6,200	3,468	5,654
Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning of period	236	685	840
OCI before reclassifications	606	(677)	(243)
Deferred income tax benefit (expense)	(212)	237	87
OCI before reclassifications, net of income tax	630	245	684
Amounts reclassified from AOCI	682	(14)	2
Deferred income tax benefit (expense)	(239)	5	(1)
Amounts reclassified from AOCI, net of income tax	443	(9)	1
Balance end of period	1,073	236	685
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning of period	31	18	37
OCI before reclassifications	(44)	22	(30)
Deferred income tax benefit (expense)	10	(9)	11
OCI before reclassifications, net of income tax	(3)	31	18
Amounts reclassified from AOCI	0	0	0
Deferred income tax benefit (expense)	0	0	0
Amounts reclassified from AOCI, net of income tax	0	0	0
Balance end of period	(3)	31	18
Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning of period	(1,577)	(2,349)	(1,851)
OCI before reclassifications	(1,181)	1,396	(618)
Deferred income tax benefit (expense)	406	(490)	217
OCI before reclassifications, net of income tax	(2,352)	(1,443)	(2,252)
Amounts reclassified from AOCI	180	(205)	(148)
Deferred income tax benefit (expense)	(64)	71	51
Amounts reclassified from AOCI, net of income tax	116	(134)	(97)
Balance end of period	$ (2,236)	$ (1,577)	$ (2,349)