Loan Servicing - Residential Mortgage Banking Activities (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Disclosures Pertaining to Servicing Assets and Servicing Liabilities [Abstract]
UPB of mortgage loan servicing portfolio	$ 118,040	$ 116,817
UPB of home equity loan servicing portfolio	4,420	5,352
UPB of residential mortgage and home equity loan servicing portfolio	122,460	122,169
UPB of residential mortgage loans serviced for others (primarily agency conforming fixed rate)	90,157	91,132
Mortgage loans sold with recourse	610	702
Maximum recourse exposure from mortgage loans sold with recourse liability	296	326
Indemnification, recourse and repurchase reserves	77	79
FHA-insured mortgage loan reserve	$ 0	$ 85