Loans - Consumer, Excluding Credit Card Loans, Other Consumer Loans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	747,508	$ 724,177	$ 726,835
Consumer, excluding credit card
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	294,979	288,449	292,620
Consumer, excluding credit card | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	54,536	52,757
% of 30 days past due to total retained loans	1.23%	1.15%
Consumer, excluding credit card | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	20,058	18,951
% of 30 days past due to total retained loans	1.73%	2.32%
Consumer, excluding credit card | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	10,970	11,557
% of 30 days past due to total retained loans	2.15%	2.52%
Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	85,564	83,265
% of 30 days past due to total retained loans	1.47%	1.60%
Consumer, excluding credit card | California | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	6,294	5,615
Consumer, excluding credit card | California | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	3,008	2,374
Consumer, excluding credit card | California | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,143	1,112
Consumer, excluding credit card | California | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	10,445	9,101
Consumer, excluding credit card | New York | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	3,662	3,898
Consumer, excluding credit card | New York | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	3,187	3,084
Consumer, excluding credit card | New York | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,259	1,218
Consumer, excluding credit card | New York | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	8,108	8,200
Consumer, excluding credit card | Illinois | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	3,175	2,917
Consumer, excluding credit card | Illinois | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,373	1,341
Consumer, excluding credit card | Illinois | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	729	740
Consumer, excluding credit card | Illinois | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	5,277	4,998
Consumer, excluding credit card | Florida | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	2,301	2,012
Consumer, excluding credit card | Florida | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	827	646
Consumer, excluding credit card | Florida | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	521	539
Consumer, excluding credit card | Florida | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	3,649	3,197
Consumer, excluding credit card | Texas | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	5,608	5,310
Consumer, excluding credit card | Texas | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	2,626	2,646
Consumer, excluding credit card | Texas | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	868	878
Consumer, excluding credit card | Texas | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	9,102	8,834
Consumer, excluding credit card | New Jersey | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,945	2,014
Consumer, excluding credit card | New Jersey | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	451	392
Consumer, excluding credit card | New Jersey | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	378	397
Consumer, excluding credit card | New Jersey | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	2,774	2,803
Consumer, excluding credit card | Arizona | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	2,003	1,855
Consumer, excluding credit card | Arizona | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,083	1,046
Consumer, excluding credit card | Arizona | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	239	252
Consumer, excluding credit card | Arizona | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	3,325	3,153
Consumer, excluding credit card | Washington | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,019	950
Consumer, excluding credit card | Washington | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	258	234
Consumer, excluding credit card | Washington | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	235	227
Consumer, excluding credit card | Washington | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,512	1,411
Consumer, excluding credit card | Michigan | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,633	1,902
Consumer, excluding credit card | Michigan | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,375	1,383
Consumer, excluding credit card | Michigan | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	466	513
Consumer, excluding credit card | Michigan | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	3,474	3,798
Consumer, excluding credit card | Ohio | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	2,157	2,229
Consumer, excluding credit card | Ohio | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,354	1,316
Consumer, excluding credit card | Ohio | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	629	708
Consumer, excluding credit card | Ohio | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	4,140	4,253
Consumer, excluding credit card | All other | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	24,739	24,055
Consumer, excluding credit card | All other | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	4,516	4,489
Consumer, excluding credit card | All other | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	4,503	4,973
Consumer, excluding credit card | All other | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	33,758	33,517
In Process of Active or Suspended Foreclosure | Consumer, excluding credit card
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,500	2,100
Current and less than 30 days past due and still accruing | Consumer, excluding credit card | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	53,866	52,152
Current and less than 30 days past due and still accruing | Consumer, excluding credit card | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	19,710	18,511
Current and less than 30 days past due and still accruing | Consumer, excluding credit card | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	10,080	10,529
Current and less than 30 days past due and still accruing | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	83,656	81,192
Days Past Due, 30 to 119 | Consumer, excluding credit card | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	663	599
Days Past Due, 30 to 119 | Consumer, excluding credit card | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	208	280
Days Past Due, 30 to 119 | Consumer, excluding credit card | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	576	660
Days Past Due, 30 to 119 | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,447	1,539
Days Past Due, 120 or More | Consumer, excluding credit card | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	7	6
Days Past Due, 120 or More | Consumer, excluding credit card | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	140	160
Days Past Due, 120 or More | Consumer, excluding credit card | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	314	368
Days Past Due, 120 or More | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	461	534
90 or more days past due and still accruing | Consumer, excluding credit card | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	0	0
90 or more days past due and still accruing | Consumer, excluding credit card | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	0	0
90 or more days past due and still accruing | Consumer, excluding credit card | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	367	428
90 or more days past due and still accruing | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	367	428
Nonaccrual | Consumer, excluding credit card | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	115	161
Nonaccrual | Consumer, excluding credit card | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	279	385
Nonaccrual | Consumer, excluding credit card | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	270	86
Nonaccrual | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	664	632
Noncriticized | Consumer, excluding credit card | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	9,822	9,968
Noncriticized | Consumer, excluding credit card | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	14,619	13,622
Noncriticized | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	24,441	23,590
Criticized performing | Consumer, excluding credit card | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	35	54
Criticized performing | Consumer, excluding credit card | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	708	711
Criticized performing | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	743	765
Criticized nonaccrual | Consumer, excluding credit card | Auto
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	0	38
Criticized nonaccrual | Consumer, excluding credit card | Business banking
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	213	316
Criticized nonaccrual | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	213	354
Student and Other Loans Insured or Guaranteed by U.S. Government Agencies | Current and less than 30 days past due and still accruing | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	4,300	4,900
Student and Other Loans Insured or Guaranteed by U.S. Government Agencies | Days Past Due, 30 to 119 | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	364	387
Student and Other Loans Insured or Guaranteed by U.S. Government Agencies | Days Past Due, 120 or More | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	290	350
Student and Other Loans Insured or Guaranteed by U.S. Government Agencies | Days Past Due, 30 or More, and Still Accruing | Consumer, excluding credit card | Student and other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	654	$ 737
Student and Other Loans Insured or Guaranteed by U.S. Government Agencies | Minimum | Days Past Due, 30 to 119 | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans, charge-off criteria, period past due	30 days
Student and Other Loans Insured or Guaranteed by U.S. Government Agencies | Minimum | Days Past Due, 120 or More | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans, charge-off criteria, period past due	120 days
Student and Other Loans Insured or Guaranteed by U.S. Government Agencies | Minimum | Days Past Due, 30 or More, and Still Accruing | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans, charge-off criteria, period past due	30 days
Student and Other Loans Insured or Guaranteed by U.S. Government Agencies | Maximum | Days Past Due, 30 to 119 | Consumer, excluding credit card | Other Consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans, charge-off criteria, period past due	119 days