CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 33	$ 204	$ 166	$ 455
Net change in unrealized gains (losses), net of tax:
Investment securities	(112)	5	374	(236)
Derivatives designated as cash flow hedges	9	(32)	(47)	(20)
Pension and post-retirement benefit plans	0	0	0	1
Total other comprehensive income (loss)	(103)	(27)	327	(255)
Comprehensive income (loss)	$ (70)	$ 177	$ 493	$ 200