Equity Changes in AOCI (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 1,203	$ 384
Other comprehensive income before reclassifications	759	1,099
Amounts reclassified from other comprehensive income	(229)	(280)
Total other comprehensive income	530	819	1,619
Ending balance	1,733	1,203	384
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	1,627	934
Other comprehensive income before reclassifications	722	983
Amounts reclassified from other comprehensive income	(228)	(290)
Total other comprehensive income	494	693
Ending balance	2,121	1,627
Accumulated Other Comprehensive Income (Loss), Other [Member]
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(424)	(550)
Other comprehensive income before reclassifications	37	116
Amounts reclassified from other comprehensive income	(1)	10
Total other comprehensive income	36	126
Ending balance	$ (388)	$ (424)