Equity Changes in AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 1,641	$ 1,575	$ 1,733	$ 1,203
OCI before reclassifications	(81)	221	(57)	561
Amounts reclassified from OCI	(200)	(176)	(316)	(144)
Total other comprehensive (loss) income	(281)	45	(373)	417
Ending balance	1,360	1,620	1,360	1,620
Available-for-Sale Securities [Member]
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	2,030	1,999	2,121	1,627
OCI before reclassifications	(81)	221	(57)	561
Amounts reclassified from OCI	(199)	(176)	(314)	(144)
Total other comprehensive (loss) income	(280)	45	(371)	417
Ending balance	1,750	2,044	1,750	2,044
Accumulated Other Comprehensive Income (Loss), Other [Member]
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(389)	(424)	(388)	(424)
OCI before reclassifications	0	0	0	0
Amounts reclassified from OCI	(1)	0	(2)	0
Total other comprehensive (loss) income	(1)	0	(2)	0
Ending balance	$ (390)	$ (424)	$ (390)	$ (424)