Credit Risk Concentrations (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Concentration Risk [Line Items]
Loans	$ 733,796	$ 723,720
Derivative receivables balance	74,983	92,477
Off-balance sheet	1,027,988	975,662
Credit exposure	1,860,528	1,809,420
Utilities Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	6,814	5,191
Derivative receivables balance	2,649	3,602
Off-balance sheet	20,070	19,857
Credit exposure	29,533	28,650
Receivables From Customers Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	23,800	17,600
Consumer
Concentration Risk [Line Items]
Loans	420,613	440,704
Derivative receivables balance	0	0
Off-balance sheet	593,174	592,923
Credit exposure	1,013,900	1,033,727
Consumer, Excluding Credit Card
Concentration Risk [Line Items]
Loans	292,620	308,427
Derivative receivables balance	0	0
Off-balance sheet	60,156	62,307
Credit exposure	352,889	370,834
Consumer, Excluding Credit Card | Receivables From Customers Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Credit exposure	113	100
Credit Card
Concentration Risk [Line Items]
Loans	127,993	132,277
Derivative receivables balance	0	0
Off-balance sheet	533,018	530,616
Credit exposure	661,011	662,893
Wholesale
Concentration Risk [Line Items]
Loans	313,183	283,016
Derivative receivables balance	74,983	92,477
Off-balance sheet	434,814	382,739
Credit exposure	846,628	775,693
Wholesale | Real Estate Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	60,740	54,684
Derivative receivables balance	1,084	1,155
Off-balance sheet	14,374	11,755
Credit exposure	76,198	67,594
Wholesale | Banks and Finance Companies Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	26,651	29,392
Derivative receivables balance	19,846	20,372
Off-balance sheet	26,821	21,676
Credit exposure	73,318	71,440
Wholesale | Healthcare Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	11,638	8,908
Derivative receivables balance	3,359	3,021
Off-balance sheet	33,490	30,318
Credit exposure	48,487	42,247
Wholesale | Oil and Gas Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	14,704	10,780
Derivative receivables balance	2,345	3,521
Off-balance sheet	25,514	21,136
Credit exposure	42,563	35,437
Wholesale | State and Municipal Governments Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	7,998	7,144
Derivative receivables balance	5,138	6,575
Off-balance sheet	28,685	28,211
Credit exposure	41,821	41,930
Wholesale | Consumer Products Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	9,151	9,187
Derivative receivables balance	826	1,079
Off-balance sheet	22,801	19,371
Credit exposure	32,778	29,637
Wholesale | Asset Managers Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	6,220	6,182
Derivative receivables balance	8,390	9,458
Off-balance sheet	16,864	17,825
Credit exposure	31,474	33,465
Wholesale | Retail and Consumer Services Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	7,901	6,353
Derivative receivables balance	429	565
Off-balance sheet	17,267	15,973
Credit exposure	25,597	22,891
Wholesale | Central Government Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	1,333	623
Derivative receivables balance	11,232	10,813
Off-balance sheet	8,658	5,702
Credit exposure	21,223	17,138
Wholesale | Metals and Mining Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	6,059	6,073
Derivative receivables balance	624	690
Off-balance sheet	14,275	8,491
Credit exposure	20,958	15,254
Wholesale | Transportation Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	12,763	10,000
Derivative receivables balance	673	947
Off-balance sheet	6,391	5,358
Credit exposure	19,827	16,305
Wholesale | Machinery and Equipment Manufacturing Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	6,304	5,111
Derivative receivables balance	592	417
Off-balance sheet	11,608	10,970
Credit exposure	18,504	16,498
Wholesale | Technology Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	3,806	4,394
Derivative receivables balance	1,192	1,310
Off-balance sheet	13,490	12,194
Credit exposure	18,488	17,898
Wholesale | Media Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	3,967	3,655
Derivative receivables balance	973	202
Off-balance sheet	11,067	8,052
Credit exposure	16,007	11,909
Wholesale | Other Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	120,173	110,718
Derivative receivables balance	15,631	28,750
Off-balance sheet	163,439	145,850
Credit exposure	299,243	285,318
Wholesale | Loans Retained [Member]
Concentration Risk [Line Items]
Loans	306,222	278,395
Derivative receivables balance	74,983	92,477
Off-balance sheet	434,814	382,739
Credit exposure	816,019	753,611
Wholesale | Loans Held-For-Sale and Loans At Fair Value Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	6,961	4,621
Derivative receivables balance	0	0
Off-balance sheet	0	0
Credit exposure	6,961	4,621
Wholesale | Receivables From Customers Credit Risk Concentration [Member]
Concentration Risk [Line Items]
Loans	0	0
Derivative receivables balance	0	0
Off-balance sheet	0	0
Credit exposure	$ 23,648	$ 17,461