Loans - Wholesale Loan Portfolio - By Class of Receivable (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
Wholesale
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	324,502	308,263	306,222
% of total criticized to total retained loans	1.45%	2.02%
% of nonaccrual loans to total retained loans	0.18%	0.27%
Net charge-offs/(recoveries)	12	16
% of net charge-offs/(recoveries) to end-of-period retained loans	0.00%	0.01%
Wholesale | Current and less than 30 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	321,612	305,548
Wholesale | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	2,215	1,844
Wholesale | 90 or more days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	76	50
Wholesale | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	599	821
Wholesale | Total non-U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	100,865	104,057
Wholesale | Total U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	223,637	204,206
Wholesale | Investment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	241,666	226,070
Wholesale | Total noninvestment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	82,836	82,193
Wholesale | Noncriticized
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	78,118	75,964
Wholesale | Criticized performing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	4,119	5,408
Wholesale | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	599	821
Wholesale | Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	109,625	103,846
% of total criticized to total retained loans	2.22%	2.58%
% of nonaccrual loans to total retained loans	0.17%	0.28%
Net charge-offs/(recoveries)	22	99
% of net charge-offs/(recoveries) to end-of-period retained loans	0.02%	0.10%
Wholesale | Commercial and industrial | Current and less than 30 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	108,857	103,357
Wholesale | Commercial and industrial | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	566	181
Wholesale | Commercial and industrial | 90 or more days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	14	14
Wholesale | Commercial and industrial | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	188	294
Wholesale | Commercial and industrial | Total non-U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	33,739	34,440
Wholesale | Commercial and industrial | Total U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	75,886	69,406
Wholesale | Commercial and industrial | Investment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	63,069	57,690
Wholesale | Commercial and industrial | Total noninvestment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	46,556	46,156
Wholesale | Commercial and industrial | Noncriticized
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	44,117	43,477
Wholesale | Commercial and industrial | Criticized performing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	2,251	2,385
Wholesale | Commercial and industrial | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	188	294
Wholesale | Real estate
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	79,113	69,151
% of total criticized to total retained loans	1.98%	3.72%
% of nonaccrual loans to total retained loans	0.32%	0.50%
Net charge-offs/(recoveries)	(9)	6
% of net charge-offs/(recoveries) to end-of-period retained loans	(0.01%)	0.01%
Wholesale | Real estate | Current and less than 30 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	78,552	68,627
Wholesale | Real estate | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	275	164
Wholesale | Real estate | 90 or more days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	33	14
Wholesale | Real estate | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	253	346
Wholesale | Real estate | Total non-U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	2,099	1,369
Wholesale | Real estate | Total U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	77,014	67,782
Wholesale | Real estate | Investment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	61,006	52,195
Wholesale | Real estate | Total noninvestment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	18,107	16,956
Wholesale | Real estate | Noncriticized
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	16,541	14,381
Wholesale | Real estate | Criticized performing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,313	2,229
Wholesale | Real estate | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	253	346
Wholesale | Financial institutions
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	34,530	33,683
% of total criticized to total retained loans	0.97%	0.88%
% of nonaccrual loans to total retained loans	0.05%	0.07%
Net charge-offs/(recoveries)	(12)	(99)
% of net charge-offs/(recoveries) to end-of-period retained loans	(0.04%)	(0.29%)
Wholesale | Financial institutions | Current and less than 30 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	34,408	33,426
Wholesale | Financial institutions | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	104	226
Wholesale | Financial institutions | 90 or more days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	0	6
Wholesale | Financial institutions | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	18	25
Wholesale | Financial institutions | Total non-U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	20,944	22,726
Wholesale | Financial institutions | Total U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	13,586	10,957
Wholesale | Financial institutions | Investment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	27,111	26,712
Wholesale | Financial institutions | Total noninvestment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	7,419	6,971
Wholesale | Financial institutions | Noncriticized
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	7,085	6,674
Wholesale | Financial institutions | Criticized performing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	316	272
Wholesale | Financial institutions | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	18	25
Wholesale | Government agencies
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	8,696	10,462
% of total criticized to total retained loans	0.03%	0.41%
% of nonaccrual loans to total retained loans	0.00%	0.01%
Net charge-offs/(recoveries)	25	1
% of net charge-offs/(recoveries) to end-of-period retained loans	0.29%	0.01%
Wholesale | Government agencies | Current and less than 30 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	8,627	10,421
Wholesale | Government agencies | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	69	40
Wholesale | Government agencies | 90 or more days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	0	0
Wholesale | Government agencies | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	0	1
Wholesale | Government agencies | Total non-U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,122	2,146
Wholesale | Government agencies | Total U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	7,574	8,316
Wholesale | Government agencies | Investment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	8,393	9,979
Wholesale | Government agencies | Total noninvestment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	303	483
Wholesale | Government agencies | Noncriticized
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	300	440
Wholesale | Government agencies | Criticized performing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	3	42
Wholesale | Government agencies | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	0	1
Wholesale | Other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	92,538	91,121
% of total criticized to total retained loans	0.41%	0.70%
% of nonaccrual loans to total retained loans	0.15%	0.17%
Net charge-offs/(recoveries)	(14)	9
% of net charge-offs/(recoveries) to end-of-period retained loans	(0.02%)	0.01%
Wholesale | Other | Current and less than 30 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	91,168	89,717
Wholesale | Other | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,201	1,233
Wholesale | Other | 90 or more days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	29	16
Wholesale | Other | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	140	155
Wholesale | Other | Total non-U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	42,961	43,376
Wholesale | Other | Total U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	49,577	47,745
Wholesale | Other | Investment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	82,087	79,494
Wholesale | Other | Total noninvestment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	10,451	11,627
Wholesale | Other | Noncriticized
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	10,075	10,992
Wholesale | Other | Criticized performing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	236	480
Wholesale | Other | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 140	$ 155