Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Total net revenue	$ 454	$ 73	$ 445	$ 456	$ 461	$ 440	$ 438	$ 475	$ 1,428	$ 1,814	$ 1,723
Net income (loss)	$ 89	$ (153)	$ 292	$ 40	$ 41	$ 86	$ 69	$ 97	$ 268	$ 293	$ 86
Earnings (loss) per share:
Basic (in dollars per share)	$ 0.31	$ (0.53)	$ 1.01	$ 0.14	$ 0.14	$ 0.30	$ 0.24	$ 0.34	$ 0.92	$ 1.02	$ 0.30
Diluted (in dollars per share)	$ 0.30	$ (0.53)	$ 0.99	$ 0.14	$ 0.14	$ 0.29	$ 0.24	$ 0.33	$ 0.91	$ 1.00	$ 0.29
Debt Instrument [Line Items]
Gains (Losses) on early extinguishment of debt		$ (39)		$ (73)					$ (112)	$ (71)	$ 0
Quarterly Financial Information Disclosure Details (Textuals) [Abstract]
Reclassification of deferred losses on cash flow hedges		(370)							(370)	0	$ 0
Termination of legacy wholesale funding obligations		$ 4,400							$ 4,400
Senior Notes Interest Bearing Six And Three Fourths Percent and Six Percent [Member]
Debt Instrument [Line Items]
Gains (Losses) on early extinguishment of debt					$ (59)					$ (59)