Loans - Troubled Debt Restructurings (Details) (USD $) In Millions, unless otherwise specified										3 Months Ended			3 Months Ended		3 Months Ended						3 Months Ended					3 Months Ended				3 Months Ended						3 Months Ended		3 Months Ended			3 Months Ended						3 Months Ended		3 Months Ended			3 Months Ended						3 Months Ended		3 Months Ended			3 Months Ended						3 Months Ended		3 Months Ended					3 Months Ended			3 Months Ended				3 Months Ended			3 Months Ended			3 Months Ended					3 Months Ended		12 Months Ended	3 Months Ended													3 Months Ended						3 Months Ended						3 Months Ended						3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Apr. 05, 2012 Mortgage Foreclosure Investigations and Litigation [Member] Global settlement on servicing and origination of mortgages [Member] Settlement of Litigation, Additional Relief Provided to Certain Borrowers [Member]	Mar. 31, 2013 Consumer, excluding credit card	Dec. 31, 2012 Consumer, excluding credit card	Mar. 31, 2012 Consumer, excluding credit card	Mar. 31, 2013 Consumer, excluding credit card Consumer Loan Excluding Credit Card	Dec. 31, 2012 Consumer, excluding credit card Consumer Loan Excluding Credit Card	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member]	Mar. 31, 2012 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member]	Dec. 31, 2012 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member]	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Maximum	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Trial Modifications Approved On Or After July 1, 2010 [Member]	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Trial Modification [Member]	Mar. 31, 2012 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Trial Modification [Member]	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Permanent Modification [Member] loans years	Mar. 31, 2012 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Permanent Modification [Member] years loans	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Nonaccrual [Member]	Dec. 31, 2012 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Regulatory Guidance Regarding Chapter 7 Loans [Member] loans	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Regulatory Guidance Regarding Chapter 7 Loans [Member] Maximum	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Regulatory Guidance Regarding Chapter 7 Loans [Member] Minimum	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Regulatory Guidance Regarding Chapter 7 Loans [Member] Days Past Due, 30 or More [Member] Maximum	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Regulatory Guidance Regarding Chapter 7 Loans [Member] Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate, Excluding Purchased Credit-Impaired [Member] Regulatory Guidance Regarding Chapter 7 Loans [Member] Days Past Due, 60 or Less [Member] Maximum	Mar. 31, 2013 Consumer, excluding credit card Home Equity - Senior Lien	Mar. 31, 2012 Consumer, excluding credit card Home Equity - Senior Lien	Dec. 31, 2012 Consumer, excluding credit card Home Equity - Senior Lien	Mar. 31, 2013 Consumer, excluding credit card Home Equity - Senior Lien Trial Modification [Member]	Mar. 31, 2012 Consumer, excluding credit card Home Equity - Senior Lien Trial Modification [Member]	Mar. 31, 2013 Consumer, excluding credit card Home Equity - Senior Lien Permanent Modification [Member] years loans	Mar. 31, 2012 Consumer, excluding credit card Home Equity - Senior Lien Permanent Modification [Member] years loans	Mar. 31, 2013 Consumer, excluding credit card Home Equity - Senior Lien Nonaccrual [Member]	Dec. 31, 2012 Consumer, excluding credit card Home Equity - Senior Lien Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Home Equity - Senior Lien Regulatory Guidance Regarding Chapter 7 Loans [Member] loans	Mar. 31, 2013 Consumer, excluding credit card Home Equity - Senior Lien Regulatory Guidance Regarding Chapter 7 Loans [Member] Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Home Equity - Junior Lien	Mar. 31, 2012 Consumer, excluding credit card Home Equity - Junior Lien	Dec. 31, 2012 Consumer, excluding credit card Home Equity - Junior Lien	Mar. 31, 2013 Consumer, excluding credit card Home Equity - Junior Lien Trial Modification [Member]	Mar. 31, 2012 Consumer, excluding credit card Home Equity - Junior Lien Trial Modification [Member]	Mar. 31, 2013 Consumer, excluding credit card Home Equity - Junior Lien Permanent Modification [Member] years loans	Mar. 31, 2012 Consumer, excluding credit card Home Equity - Junior Lien Permanent Modification [Member] loans years	Mar. 31, 2013 Consumer, excluding credit card Home Equity - Junior Lien Nonaccrual [Member]	Dec. 31, 2012 Consumer, excluding credit card Home Equity - Junior Lien Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Home Equity - Junior Lien Regulatory Guidance Regarding Chapter 7 Loans [Member] loans	Mar. 31, 2013 Consumer, excluding credit card Home Equity - Junior Lien Regulatory Guidance Regarding Chapter 7 Loans [Member] Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Prime Mortgages, Including Option ARMs	Mar. 31, 2012 Consumer, excluding credit card Prime Mortgages, Including Option ARMs	Dec. 31, 2012 Consumer, excluding credit card Prime Mortgages, Including Option ARMs	Mar. 31, 2013 Consumer, excluding credit card Prime Mortgages, Including Option ARMs Trial Modification [Member]	Mar. 31, 2012 Consumer, excluding credit card Prime Mortgages, Including Option ARMs Trial Modification [Member]	Mar. 31, 2013 Consumer, excluding credit card Prime Mortgages, Including Option ARMs Permanent Modification [Member] years loans	Mar. 31, 2012 Consumer, excluding credit card Prime Mortgages, Including Option ARMs Permanent Modification [Member] loans years	Mar. 31, 2013 Consumer, excluding credit card Prime Mortgages, Including Option ARMs Nonaccrual [Member]	Dec. 31, 2012 Consumer, excluding credit card Prime Mortgages, Including Option ARMs Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Prime Mortgages, Including Option ARMs Regulatory Guidance Regarding Chapter 7 Loans [Member] loans	Mar. 31, 2013 Consumer, excluding credit card Prime Mortgages, Including Option ARMs Regulatory Guidance Regarding Prime, including Option ARM, mortgages [Member] Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Subprime Mortgages	Mar. 31, 2012 Consumer, excluding credit card Subprime Mortgages	Dec. 31, 2012 Consumer, excluding credit card Subprime Mortgages	Mar. 31, 2013 Consumer, excluding credit card Subprime Mortgages Trial Modification [Member]	Mar. 31, 2012 Consumer, excluding credit card Subprime Mortgages Trial Modification [Member]	Mar. 31, 2013 Consumer, excluding credit card Subprime Mortgages Permanent Modification [Member] loans years	Mar. 31, 2012 Consumer, excluding credit card Subprime Mortgages Permanent Modification [Member] loans years	Mar. 31, 2013 Consumer, excluding credit card Subprime Mortgages Nonaccrual [Member]	Dec. 31, 2012 Consumer, excluding credit card Subprime Mortgages Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Subprime Mortgages Regulatory Guidance Regarding Chapter 7 Loans [Member] loans	Mar. 31, 2013 Consumer, excluding credit card Subprime Mortgages Regulatory Guidance Regarding Chapter 7 Loans [Member] Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Other Consumer [Member]	Mar. 31, 2012 Consumer, excluding credit card Other Consumer [Member]	Dec. 31, 2012 Consumer, excluding credit card Other Consumer [Member]	Mar. 31, 2013 Consumer, excluding credit card Other Consumer [Member] Nonaccrual [Member]	Dec. 31, 2012 Consumer, excluding credit card Other Consumer [Member] Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Auto Loans	Mar. 31, 2012 Consumer, excluding credit card Auto Loans	Dec. 31, 2012 Consumer, excluding credit card Auto Loans	Mar. 31, 2013 Consumer, excluding credit card Auto Loans Maximum	Mar. 31, 2013 Consumer, excluding credit card Auto Loans Nonaccrual [Member]	Dec. 31, 2012 Consumer, excluding credit card Auto Loans Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Auto Loans Regulatory Guidance Regarding Chapter 7 Loans [Member] Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Business Banking Loans years	Mar. 31, 2012 Consumer, excluding credit card Business Banking Loans years	Dec. 31, 2012 Consumer, excluding credit card Business Banking Loans	Mar. 31, 2013 Consumer, excluding credit card Business Banking Loans Maximum	Mar. 31, 2013 Consumer, excluding credit card Business Banking Loans Nonaccrual [Member]	Dec. 31, 2012 Consumer, excluding credit card Business Banking Loans Nonaccrual [Member]	Mar. 31, 2013 Consumer, excluding credit card Scored Auto and Business Banking Loans [Member] loan_payment	Mar. 31, 2013 Consumer, excluding credit card Residential Real Estate [Member] loan_payment	Mar. 31, 2013 Credit card	Dec. 31, 2012 Credit card	Mar. 31, 2012 Credit card	Mar. 31, 2013 Credit card Credit Card Loan loan_payment	Mar. 31, 2012 Credit card Credit Card Loan	Dec. 31, 2012 Credit card Credit Card Loan	Mar. 31, 2013 Credit card Credit Card Loan Credit Card Loan Modification Programs, Total [Member]	Mar. 31, 2012 Credit card Credit Card Loan Credit Card Loan Modification Programs, Total [Member]	Mar. 31, 2013 Credit card Credit Card Loan Short-Term Credit Card Loan Modification Programs [Member]	Mar. 31, 2012 Credit card Credit Card Loan Short-Term Credit Card Loan Modification Programs [Member]	Mar. 31, 2013 Credit card Credit Card Loan Long-Term Credit Card Loan Modification Programs [Member]	Mar. 31, 2012 Credit card Credit Card Loan Long-Term Credit Card Loan Modification Programs [Member]	Mar. 31, 2013 Credit card Credit Card Loan Maximum	Mar. 31, 2013 Credit card Credit Card Loan Days Past Due, 30 or More [Member]	Mar. 31, 2013 Credit card Credit Card Loan Nonaccrual [Member]	Dec. 31, 2012 Credit card Credit Card Loan Nonaccrual [Member]	Mar. 31, 2013 Wholesale	Dec. 31, 2012 Wholesale	Mar. 31, 2012 Wholesale	Mar. 31, 2013 Wholesale Wholesale Loan [Member] years	Mar. 31, 2012 Wholesale Wholesale Loan [Member] years	Dec. 31, 2012 Wholesale Wholesale Loan [Member]	Mar. 31, 2013 Wholesale Wholesale Loan [Member] Nonaccrual [Member]	Dec. 31, 2012 Wholesale Wholesale Loan [Member] Nonaccrual [Member]	Mar. 31, 2012 Wholesale Wholesale Loan [Member] Nonaccrual [Member]	Mar. 31, 2013 Wholesale Commercial and Industrial [Member]	Mar. 31, 2012 Wholesale Commercial and Industrial [Member]	Dec. 31, 2012 Wholesale Commercial and Industrial [Member]	Mar. 31, 2013 Wholesale Commercial and Industrial [Member] Nonaccrual [Member]	Dec. 31, 2012 Wholesale Commercial and Industrial [Member] Nonaccrual [Member]	Mar. 31, 2012 Wholesale Commercial and Industrial [Member] Nonaccrual [Member]	Mar. 31, 2013 Wholesale Wholesale Real Estate [Member]	Mar. 31, 2012 Wholesale Wholesale Real Estate [Member]	Dec. 31, 2012 Wholesale Wholesale Real Estate [Member]	Mar. 31, 2013 Wholesale Wholesale Real Estate [Member] Nonaccrual [Member]	Dec. 31, 2012 Wholesale Wholesale Real Estate [Member] Nonaccrual [Member]	Mar. 31, 2012 Wholesale Wholesale Real Estate [Member] Nonaccrual [Member]	Mar. 31, 2013 Wholesale Financial Institutions, Government Agencies and Other Wholesale [Member]	Mar. 31, 2012 Wholesale Financial Institutions, Government Agencies and Other Wholesale [Member]	Mar. 31, 2013 Wholesale Financial Institutions, Government Agencies and Other Wholesale [Member] Nonaccrual [Member]	Mar. 31, 2012 Wholesale Financial Institutions, Government Agencies and Other Wholesale [Member] Nonaccrual [Member]	Mar. 31, 2013 Wholesale Financial Institutions [Member]	Dec. 31, 2012 Wholesale Financial Institutions [Member]	Mar. 31, 2013 Wholesale Financial Institutions [Member] Nonaccrual [Member]	Dec. 31, 2012 Wholesale Financial Institutions [Member] Nonaccrual [Member]	Mar. 31, 2013 Wholesale Government Agencies [Member]	Dec. 31, 2012 Wholesale Government Agencies [Member]	Mar. 31, 2013 Wholesale Government Agencies [Member] Nonaccrual [Member]	Dec. 31, 2012 Wholesale Government Agencies [Member] Nonaccrual [Member]	Mar. 31, 2013 Wholesale Wholesale Other [Member]	Dec. 31, 2012 Wholesale Wholesale Other [Member]	Mar. 31, 2013 Wholesale Wholesale Other [Member] Nonaccrual [Member]	Dec. 31, 2012 Wholesale Wholesale Other [Member] Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Number of Years Before Payment Default Under a Modified Loan																																																																															1 year							1 year																	1 year
Number of Payments Past Due for Deemed Payment Default																																																																																									2	2				2
Number of Months Before a Payment Redefault Under Modified Loan													12 months
Loans Modified in Troubled Debt Restructurings [Abstract]
Financing Receivable, Modifications, Recorded Investment										$ 13,507	$ 9,288				$ 466	$ 462	$ 13,041	$ 8,826							$ 1,700		$ 1,155	$ 338		$ 39	$ 42	$ 1,116	$ 296				$ 482	$ 1,286	$ 706		$ 5	$ 11	$ 1,281	$ 695				$ 501	$ 7,223	$ 5,018		$ 265	$ 250	$ 6,958	$ 4,768				$ 441	$ 3,843	$ 3,226		$ 157	$ 159	$ 3,686	$ 3,067				$ 236	$ 481	$ 469		$ 289	$ 312	$ 140	$ 91			$ 102	$ 109	$ 66	$ 341	$ 378			$ 187	$ 203						$ 3,798		$ 4,189														$ 421	$ 664		$ 357		$ 525	$ 254	$ 419		$ 200		$ 314	$ 124	$ 148		$ 114		$ 116	$ 43	$ 97	$ 43	$ 95
Loans and Leases Receivable, Impaired, Troubled Debt Restructuring, Funded Commitment To Lend																																																																																																														18	15					18	15					0	0					0	0
Loans Receivable Held for Investment, Net of Deferred Income	722,529	726,835	712,898		290,082	292,620	304,770	290,082	292,620	150,427		151,896							8,375	8,460							18,743		19,385					943	931			46,055		48,000					2,161	2,277			77,626		76,256					3,479	3,445			8,003		8,255					1,792	1,807			81,218		80,987	673	714	50,552		49,913		135	163		18,739		18,883		458	481			121,865	127,993	124,475	121,865		127,993									1	1	310,582	306,222	283,653	310,582		306,222	1,247	1,434		111,584		109,865	453	708		61,380		60,740	564	520						43,794	36,227	7	8	8,997	9,544	0	0	84,827	89,846	223	198
Loss Contingency, Settlement Agreement, Consideration				3,700.0
Loan Modification Program, Fixed Payment Plan Period																																																																																																					60 months
Loans Modified in Troubled Debt Restructurings [Roll Forward]
Financing Receivable, Modifications, Recorded Investment, Beginning Balance										13,245	9,088														1,700		1,092	335									482	1,223	657									501	7,118	4,877									441	3,812	3,219									236	502	503		289	312	150	88			102	109	66	352	415			187	203						4,189																696	750		357		525	575	531		200		314	99	176		114		116	22	43	43	95
Financing Receivable, Modifications, New Troubled Debt Restructurings										674	511																101	12										135	96										310	281										128	122										42	30				20	17						22	13													339	511	0	31	339	480								67	70					14	4					31	3					22	63
Financing Receivable, Impaired, Troubled Debt Restructuring, Increases to Existing Troubled Debt Restructurings																																																																																																														3	1					3	1					0	0					0	0
Financing Receivable, Impaired, Troubled Debt Restructuring, Charge-offs Post-Modification										(100)	(107)																(10)	(5)										(33)	(17)										(19)	(34)										(38)	(51)										(5)	(5)				(3)	(2)						(2)	(3)																										(4)	(11)					(1)	(9)					(3)	(2)					0	0
Financing Receivable, Impaired, Troubled Debt Restructuring, Foreclosures and Other Liquidations										(62)	(69)																(4)	0										(4)	(3)										(35)	(29)										(19)	(37)										0	0				0	0						0	0
Financing Receivable, Impaired, Troubled Debt Restructuring, Principal Payments, Sales, and Other										(250)	(135)																(24)	(4)										(35)	(27)										(151)	(77)										(40)	(27)										(58)	(59)				(27)	(12)						(31)	(47)																										(341)	(146)					(337)	(108)					(3)	(29)					(1)	(9)
Financing Receivables, Impaired, Troubled Debt Restructuring, Performing Loans Restructured at Market Rates but No Longer Reported as TDRs																																																																																																														0	23
Financing Receivable, Modifications, Recorded Investment, Ending Balance										13,507	9,288				466	462	13,041	8,826							1,700		1,155	338		39	42	1,116	296				482	1,286	706		5	11	1,281	695				501	7,223	5,018		265	250	6,958	4,768				441	3,843	3,226		157	159	3,686	3,067				236	481	469		289	312	140	91			102	109	66	341	378			187	203						3,798		4,189														421	664		357		525	254	419		200		314	124	148		114		116	43	97	43	95
Nature and Extent of Modifications [Abstract]
Mortgage Loans on Real Estate, Number of Loans																					39,400															9,600											22,500											3,600											3,700
Financing Receivable, Modifications, Number of Contract Modifications that Occurred															3,161	2,783	5,026	4,186												500	371	545	230								196	248	1,316	1,816								976	972	1,476	950								1,489	1,192	1,689	1,190
Financing Receivable, Modifications, Percentage of Modifications that Occurred, Interest Rate Reductions										77.00%	86.00%																73.00%	67.00%										90.00%	95.00%										75.00%	76.00%										69.00%	84.00%
Financing Receivable, Modifications, Percentage of Modifications that Occurred, Term Or Payment Extension										65.00%	68.00%																73.00%	96.00%										78.00%	67.00%										69.00%	76.00%										50.00%	57.00%
Financing Receivable, Modifications, Percentage of Modifications that Occurred, Principal And Interest Deferred										19.00%	22.00%																10.00%	11.00%										23.00%	20.00%										27.00%	38.00%										11.00%	13.00%
Financing Receivable, Modifications, Percentage of Modifications that Occurred, Principal Forgiveness										46.00%	18.00%																39.00%	27.00%										40.00%	8.00%										41.00%	20.00%										56.00%	30.00%
Financing Receivable, Modifications, Percentage of Modifications that Occurred, Other										12.00%	2.00%																0.00%	0.00%										0.00%	0.00%										24.00%	4.00%										16.00%	3.00%
Percentage, Sum of Items by Type, May Exceed										100.00%
Financial Effects of Modifications and Redefaults [Abstract]
Financing Receivable, Modifications, Pre-Modification, Weighted-Average Interest Rate Of Loans With Rate Reductions																	6.20%	6.60%														6.37%	7.01%										5.19%	5.68%										5.64%	5.90%										7.69%	8.28%										12.97%	9.98%						8.34%	7.96%										15.49%	16.46%
Financing Receivable, Modifications, Post-Modification, Weighted-Average Interest Rate Of Loans With Rate Reductions																	3.03%	2.81%														3.51%	3.21%										2.16%	1.71%										2.87%	2.59%										3.58%	3.83%										5.04%	4.46%						5.48%	6.15%										4.67%	5.52%
Financing Receivable, Modifications, Pre-Modification, Weighted-Average Remaining Term																																																																																			1.4	1.4
Financing Receivable, Modifications, Pre-Modification, Weighted-Average Remaining Term of Financing Receivables With Term Or Payment Extensions																	23	25														19	20										19	22										24	27										23	26
Financing Receivable, Modifications, Average Term or Payment Extension Granted																																																																																																														2.4	0.9
Financing Receivable, Modifications, Post-Modification, Weighted-Average Remaining Term																																																																																			2.6	3.5																										1.7	4.1
Financing Receivable, Modifications, Post-Modification, Weighted-Average Remaining Term of Financing Receivables With Term Or Payment Extensions																	35	34														31	27										33	33										36	36										34	32
Financing Receivable, Modifications, Weighted-Average Remaining Life																																6											7											10											8
Financing Receivable, Impaired, Troubled Debt Restructuring, Write-down																	29	26														2	1										19	6										5	14										3	5
Financing Receivable, Modifications, Principal Deferred																	54	52														2	1										7	6										35	35										10	10
Financing Receivable, Modifications, Principal Forgiven																	183	57														10	2										16	4										73	20										84	31
Financing Receivable, Modifications, Subsequent Default Occurred, Number of Contracts																	1,129	1,101														147	68										380	411										234	248										368	374
Financing Receivable, Modifications, Subsequent Default Occurred, Recorded Investment																	$ 109	$ 129														$ 11	$ 5										$ 7	$ 16										$ 54	$ 67										$ 37	$ 41										$ 13	$ 7						$ 12	$ 11										$ 44	$ 97															$ 0	$ 47
Financing Receivable, Trial Modifications Successfully Converted to Permanent Modifications														85.00%
Rate of Default for Modified Loans, Estimated Weighted Average																						40.00%	10.00%									19.00%						17.00%																14.00%											24.00%																													36.49%		38.23%
Percentage of Loans Thirty Plus Days Past Due to Total Retained Loans										3.92%		4.28%															3.45%		3.60%							21.00%		2.25%		2.49%							14.00%		3.59%		3.97%							41.00%		17.89%		19.16%							30.00%		1.37%		1.58%			0.92%		1.25%					2.12%		2.12%									1.94%		2.10%
Period Past Due, Credit Analysis Factors, Charge off Criteria																								30 days		60 days												180 days
Loans, Charge-off Criteria, Period Past Due																																																																																																								30 days