Loans - Wholesale Loan Portfolio - Real Estate Class of Loans (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 | Real Estate Multifamily
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	53,319,000,000	51,049,000,000
% of total criticized to total retained loans	1.25%	1.28%
% of nonaccrual loans to total retained loans	0.24%	0.25%
Wholesale | Real Estate Commercial lessors
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	17,394,000,000	17,438,000,000
% of total criticized to total retained loans	4.58%	4.82%
% of nonaccrual loans to total retained loans	0.51%	0.63%
Wholesale | Real Estate Commercial construction and development
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	4,542,000,000	4,264,000,000
% of total criticized to total retained loans	0.62%	0.98%
% of nonaccrual loans to total retained loans	0.00%	0.00%
Wholesale | Real Estate Other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	7,152,000,000	6,362,000,000
% of total criticized to total retained loans	0.92%	0.49%
% of nonaccrual loans to total retained loans	0.62%	0.27%
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 | Criticized | Real Estate Multifamily
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	665,000,000	652,000,000
Wholesale | Criticized | Real Estate Commercial lessors
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	796,000,000	841,000,000
Wholesale | Criticized | Real Estate Commercial construction and development
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	28,000,000	42,000,000
Wholesale | Criticized | Real Estate Other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	66,000,000	31,000,000
Wholesale | Criticized | Real estate
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	1,555,000,000	1,566,000,000
Wholesale | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	696,000,000	599,000,000
Wholesale | Criticized nonaccrual | Real Estate Multifamily
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	127,000,000	126,000,000
Wholesale | Criticized nonaccrual | Real Estate Commercial lessors
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	88,000,000	110,000,000
Wholesale | Criticized nonaccrual | Real Estate Commercial construction and development
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	0	0
Wholesale | Criticized nonaccrual | Real Estate Other
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	44,000,000	17,000,000
Wholesale | Criticized nonaccrual | Real estate
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 259,000,000	$ 253,000,000