Loans - Wholesale Loan Portfolio - Real Estate Class of Loans (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 844,195	$ 832,792	$ 756,971
Wholesale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 364,312	$ 357,050	$ 331,219
% of total criticized exposure to total retained loans	2.80%	2.06%
% of criticized nonaccrual loans to total real estate retained loans	0.60%	0.28%
Wholesale | Total real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 96,101	$ 92,820
% of total criticized exposure to total retained loans	1.44%	1.60%
% of criticized nonaccrual loans to total real estate retained loans	0.26%	0.25%
Wholesale | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 61,376	$ 60,290
% of total criticized exposure to total retained loans	0.90%	0.86%
% of criticized nonaccrual loans to total real estate retained loans	0.13%	0.14%
Wholesale | Commercial lessors
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 21,672	$ 20,062
% of total criticized exposure to total retained loans	3.37%	4.21%
% of criticized nonaccrual loans to total real estate retained loans	0.52%	0.50%
Wholesale | Commercial construction and development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 5,079	$ 4,920
% of total criticized exposure to total retained loans	0.67%	0.87%
% of criticized nonaccrual loans to total real estate retained loans	0.00%	0.02%
Wholesale | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 7,974	$ 7,548
% of total criticized exposure to total retained loans	0.85%	0.99%
% of criticized nonaccrual loans to total real estate retained loans	0.76%	0.60%
Wholesale | Criticized exposure | Total real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,385	$ 1,482
Wholesale | Criticized exposure | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	553	520
Wholesale | Criticized exposure | Commercial lessors
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	730	844
Wholesale | Criticized exposure | Commercial construction and development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	34	43
Wholesale | Criticized exposure | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	68	75
Wholesale | Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	2,203	988
Wholesale | Criticized nonaccrual | Total real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	253	231
Wholesale | Criticized nonaccrual | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	80	85
Wholesale | Criticized nonaccrual | Commercial lessors
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	112	100
Wholesale | Criticized nonaccrual | Commercial construction and development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	0	1
Wholesale | Criticized nonaccrual | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 61	$ 45