Loans - Wholesale Loan Portfolio - By Class of Receivable (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 756,971,000,000	$ 747,508,000,000	$ 721,160,000,000
Wholesale
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	331,219,000,000	324,502,000,000	311,718,000,000
% of total criticized to total retained loans	1.53%	1.45%
% of nonaccrual loans to total retained loans	0.21%	0.18%
Wholesale | Current and less than 30 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	328,966,000,000	321,612,000,000
Wholesale | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,489,000,000	2,215,000,000
Wholesale | 90 or more days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	68,000,000	76,000,000
Wholesale | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	696,000,000	599,000,000
Wholesale | Total non-U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	98,870,000,000	100,865,000,000
Wholesale | Total U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	232,349,000,000	223,637,000,000
Wholesale | Investment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	248,873,000,000	241,666,000,000
Wholesale | Total noninvestment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	82,346,000,000	82,836,000,000
Wholesale | Noncriticized
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	77,290,000,000	78,118,000,000
Wholesale | Criticized performing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	4,360,000,000	4,119,000,000
Wholesale | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	696,000,000	599,000,000
Wholesale | Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	113,724,000,000	109,625,000,000
% of total criticized to total retained loans	2.56%	2.22%
% of nonaccrual loans to total retained loans	0.29%	0.17%
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	113,177,000,000	108,857,000,000
Wholesale | Commercial and industrial | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	215,000,000	566,000,000
Wholesale | Commercial and industrial | 90 or more days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	0	14,000,000
Wholesale | Commercial and industrial | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	332,000,000	188,000,000
Wholesale | Commercial and industrial | Total non-U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	33,627,000,000	33,739,000,000
Wholesale | Commercial and industrial | Total U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	80,097,000,000	75,886,000,000
Wholesale | Commercial and industrial | Investment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	66,973,000,000	63,069,000,000
Wholesale | Commercial and industrial | Total noninvestment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	46,751,000,000	46,556,000,000
Wholesale | Commercial and industrial | Noncriticized
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	43,838,000,000	44,117,000,000
Wholesale | Commercial and industrial | Criticized performing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	2,581,000,000	2,251,000,000
Wholesale | Commercial and industrial | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	332,000,000	188,000,000
Wholesale | Real estate
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	82,407,000,000	79,113,000,000
% of total criticized to total retained loans	1.89%	1.98%
% of nonaccrual loans to total retained loans	0.31%	0.32%
Wholesale | Real estate | Current and less than 30 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	82,058,000,000	78,552,000,000
Wholesale | Real estate | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	84,000,000	275,000,000
Wholesale | Real estate | 90 or more days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	6,000,000	33,000,000
Wholesale | Real estate | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	259,000,000	253,000,000
Wholesale | Real estate | Total non-U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	2,274,000,000	2,099,000,000
Wholesale | Real estate | Total U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	80,133,000,000	77,014,000,000
Wholesale | Real estate | Investment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	64,382,000,000	61,006,000,000
Wholesale | Real estate | Total noninvestment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	18,025,000,000	18,107,000,000
Wholesale | Real estate | Noncriticized
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	16,470,000,000	16,541,000,000
Wholesale | Real estate | Criticized performing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,296,000,000	1,313,000,000
Wholesale | Real estate | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	259,000,000	253,000,000
Wholesale | Financial institutions
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	35,446,000,000	34,530,000,000
% of total criticized to total retained loans	0.90%	0.97%
% of nonaccrual loans to total retained loans	0.04%	0.05%
Wholesale | Financial institutions | Current and less than 30 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	35,397,000,000	34,408,000,000
Wholesale | Financial institutions | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	34,000,000	104,000,000
Wholesale | Financial institutions | 90 or more days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	0	0
Wholesale | Financial institutions | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	15,000,000	18,000,000
Wholesale | Financial institutions | Total non-U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	19,450,000,000	20,944,000,000
Wholesale | Financial institutions | Total U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	15,996,000,000	13,586,000,000
Wholesale | Financial institutions | Investment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	28,091,000,000	27,111,000,000
Wholesale | Financial institutions | Total noninvestment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	7,355,000,000	7,419,000,000
Wholesale | Financial institutions | Noncriticized
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	7,037,000,000	7,085,000,000
Wholesale | Financial institutions | Criticized performing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	303,000,000	316,000,000
Wholesale | Financial institutions | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	15,000,000	18,000,000
Wholesale | Government agencies
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	9,058,000,000	8,696,000,000
% of total criticized to total retained loans	0.09%	0.03%
% of nonaccrual loans to total retained loans	0.00%	0.00%
Wholesale | Government agencies | Current and less than 30 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	9,000,000,000	8,627,000,000
Wholesale | Government agencies | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	58,000,000	69,000,000
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	0
Wholesale | Government agencies | Total non-U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,153,000,000	1,122,000,000
Wholesale | Government agencies | Total U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	7,905,000,000	7,574,000,000
Wholesale | Government agencies | Investment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	8,718,000,000	8,393,000,000
Wholesale | Government agencies | Total noninvestment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	340,000,000	303,000,000
Wholesale | Government agencies | Noncriticized
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	332,000,000	300,000,000
Wholesale | Government agencies | Criticized performing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	8,000,000	3,000,000
Wholesale | Government agencies | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	0	0
Wholesale | Other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	90,584,000,000	92,538,000,000
% of total criticized to total retained loans	0.29%	0.41%
% of nonaccrual loans to total retained loans	0.10%	0.15%
Wholesale | Other | Current and less than 30 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	89,334,000,000	91,168,000,000
Wholesale | Other | 30–89 days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,098,000,000	1,201,000,000
Wholesale | Other | 90 or more days past due and still accruing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	62,000,000	29,000,000
Wholesale | Other | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	90,000,000	140,000,000
Wholesale | Other | Total non-U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	42,366,000,000	42,961,000,000
Wholesale | Other | Total U.S.
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	48,218,000,000	49,577,000,000
Wholesale | Other | Investment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	80,709,000,000	82,087,000,000
Wholesale | Other | Total noninvestment grade
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	9,875,000,000	10,451,000,000
Wholesale | Other | Noncriticized
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	9,613,000,000	10,075,000,000
Wholesale | Other | Criticized performing
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	172,000,000	236,000,000
Wholesale | Other | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 90,000,000	$ 140,000,000