Mortgage Banking Activities, Mortgage Banking Noninterest Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Mortgage Banking Activities [Abstract]
Contractually specified servicing fees	$ 900	$ 949	$ 1,807	$ 1,903
Late charges	44	42	92	90
Ancillary fees	59	54	109	115
Unreimbursed direct servicing costs	(121)	(203)	(244)	(356)
Net servicing fees	882	842	1,764	1,752
Changes in fair value of MSRs carried at fair value:
Due to changes in valuation model inputs or assumptions	(360)	(824)	(186)	(1,781)
Changes due to collection/realization of expected cash flows over time	(487)	(568)	(948)	(1,059)
Total changes in fair value of MSRs carried at fair value	(847)	(1,392)	(1,134)	(2,840)
Amortization	(66)	(68)	(133)	(135)
Net Derivative Gains (Losses) From Economic Hedges Related To Mortgage Servicing Activities	431	978	359	2,433
Total servicing income, net	400	360	856	1,210
Net gains on mortgage loan origination/sales activities	748	1,054	1,520	1,802
Total mortgage banking noninterest income	1,148	1,414	2,376	3,012
Market-related valuation changes to MSRs, net of hedge results	$ 71	$ 154	$ 173	$ 652