Credit risk concentrations (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	$ 1,809,420	$ 1,765,049
Loans	723,720	692,927
Derivative receivables balance	92,477	80,481
Total lending related commitments	975,662	958,709	991,095
Receivables From Customers Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Loans	17,600	32,500
Wholesale
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	775,693	687,125
Loans	283,016	227,633
Derivative receivables balance	92,477	80,481
Total lending related commitments	382,739	346,079
Wholesale | Banks and Finance Companies Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	71,440	65,867
Loans	29,392	21,562
Derivative receivables balance	20,372	20,935
Total lending related commitments	21,676	23,370
Wholesale | Real Estate Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	67,594	64,351
Loans	54,684	53,635
Derivative receivables balance	1,155	868
Total lending related commitments	11,755	9,848
Wholesale | Healthcare Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	42,247	41,093
Loans	8,908	6,047
Derivative receivables balance	3,021	2,121
Total lending related commitments	30,318	32,925
Wholesale | State and Municipal Governments Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	41,930	35,808
Loans	7,144	6,095
Derivative receivables balance	6,575	5,148
Total lending related commitments	28,211	24,565
Wholesale | Oil and Gas Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	35,437	26,459
Loans	10,780	5,701
Derivative receivables balance	3,521	3,866
Total lending related commitments	21,136	16,892
Wholesale | Asset Managers Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	33,465	29,364
Loans	6,182	7,070
Derivative receivables balance	9,458	7,124
Total lending related commitments	17,825	15,170
Wholesale | Consumer Products Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	29,637	27,508
Loans	9,187	7,921
Derivative receivables balance	1,079	1,039
Total lending related commitments	19,371	18,548
Wholesale | Utilities Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	28,650	25,911
Loans	5,191	4,220
Derivative receivables balance	3,602	3,104
Total lending related commitments	19,857	18,587
Wholesale | Retail and Consumer Services Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	22,891	20,882
Loans	6,353	5,876
Derivative receivables balance	565	796
Total lending related commitments	15,973	14,210
Wholesale | Technology Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	17,898	14,348
Loans	4,394	2,752
Derivative receivables balance	1,310	1,554
Total lending related commitments	12,194	10,042
Wholesale | Central Government Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	17,138	11,173
Loans	623	1,146
Derivative receivables balance	10,813	6,052
Total lending related commitments	5,702	3,975
Wholesale | Machinery and Equipment Manufacturing Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	16,498	13,311
Loans	5,111	3,601
Derivative receivables balance	417	445
Total lending related commitments	10,970	9,265
Wholesale | Transportation Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	16,305	9,652
Loans	10,000	3,754
Derivative receivables balance	947	822
Total lending related commitments	5,358	5,076
Wholesale | Metals and Mining Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	15,254	11,426
Loans	6,073	3,301
Derivative receivables balance	690	1,018
Total lending related commitments	8,491	7,107
Wholesale | Insurance Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	13,092	10,918
Loans	1,109	1,103
Derivative receivables balance	2,061	1,660
Total lending related commitments	9,922	8,155
Wholesale | Other Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	284,135	240,999
Loans	113,264	88,726
Derivative receivables balance	26,891	23,929
Total lending related commitments	143,980	128,344
Wholesale | Loans Retained [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	753,611	649,070
Loans	278,395	222,510
Derivative receivables balance	92,477	80,481
Total lending related commitments	382,739	346,079
Wholesale | Loans Held-For-Sale and Loans At Fair Value Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	4,621	5,123
Loans	4,621	5,123
Derivative receivables balance	0	0
Total lending related commitments	0	0
Wholesale | Receivables From Customers Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	17,461	32,932
Loans	0		0
Derivative receivables balance	0	0
Total lending related commitments	0	0
Consumer Excluding Credit Card
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	370,834	393,021
Loans	308,427	327,618
Derivative receivables balance	0	0
Total lending related commitments	62,307	65,403
Consumer Excluding Credit Card | Receivables From Customers Credit Risk Concentration [Member]
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	100
Credit Card
Concentrations of Credit Exposure
Concentration Risk, Credit Exposure	662,893	684,903
Loans	132,277	137,676
Derivative receivables balance	0	0
Total lending related commitments	$ 530,616	$ 547,227