Loans - Wholesale Loan Portfolio - Real Estate Class of Loans (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 804,293	$ 747,508	$ 735,304
Wholesale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 346,927	$ 324,502	$ 320,361
% of total criticized to total retained loans	1.79%	1.45%
% of criticized nonaccrual to total real estate retained loans	0.31%	0.18%
Wholesale | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 58,139	$ 51,049
% of total criticized to total retained loans	0.89%	1.28%
% of criticized nonaccrual to total real estate retained loans	0.20%	0.25%
Wholesale | Commercial lessors
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 19,045	$ 17,438
% of total criticized to total retained loans	5.14%	4.82%
% of criticized nonaccrual to total real estate retained loans	0.53%	0.63%
Wholesale | Commercial construction and development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 4,832	$ 4,264
% of total criticized to total retained loans	0.83%	0.98%
% of criticized nonaccrual to total real estate retained loans	0.00%	0.00%
Wholesale | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 7,465	$ 6,362
% of total criticized to total retained loans	1.14%	0.49%
% of criticized nonaccrual to total real estate retained loans	0.58%	0.27%
Wholesale | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 89,481	$ 79,113
% of total criticized to total retained loans	1.81%	1.98%
% of criticized nonaccrual to total real estate retained loans	0.29%	0.32%
Wholesale | Criticized exposure | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 515	$ 652
Wholesale | Criticized exposure | Commercial lessors
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	978	841
Wholesale | Criticized exposure | Commercial construction and development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	40	42
Wholesale | Criticized exposure | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	85	31
Wholesale | Criticized exposure | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	1,618	1,566
Wholesale | Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	1,086	599
Wholesale | Criticized nonaccrual | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	114	126
Wholesale | Criticized nonaccrual | Commercial lessors
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	100	110
Wholesale | Criticized nonaccrual | Commercial construction and development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	0	0
Wholesale | Criticized nonaccrual | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	43	17
Wholesale | Criticized nonaccrual | Real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 257	$ 253