Consolidated Statements of Comprehensive Income - 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	$ 642	$ 533	$ 1,799	$ 1,581
OCI, net of tax:
Change in unrecognized net pension and postretirement costs	2	(14)	24	4
Change in unrealized net gains (losses) on cash flow hedges	21	(92)	(143)	(73)
Change in unrealized net gains (losses) on AFS securities	(73)	51	224	1
Change in FDIC's share of unrealized gains/losses on AFS securities	137	9	169	28
Other, net	0	(2)	4	(5)
Total OCI	87	(48)	278	(45)
Total comprehensive income	729	485	2,077	1,536
Income Tax Effect of Items Included in OCI:
Change in unrecognized net pension and postretirement costs	0	(8)	14	3
Change in unrealized net gains (losses) on cash flow hedges	14	(55)	(84)	(44)
Change in unrealized net gains (losses) on AFS securities	(43)	24	135	(7)
Change in FDIC's share of unrealized gains/losses on AFS securities	80	6	98	20
Other, net	$ 1	$ 1	$ 1	$ 1