Loans - Wholesale Loan Portfolio - Real Estate Class of Loans (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loans and Leases Receivable Disclosure [Line Items]
Retained	$ 969,415	$ 924,838	$ 889,907
Wholesale
Loans and Leases Receivable Disclosure [Line Items]
Retained	$ 439,162	$ 402,898	$ 383,790
% of total criticized exposure to total real estate retained loans	1.33%	1.71%
% of criticized nonaccrual loans to total real estate retained loans	0.26%	0.43%
Wholesale | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Retained	$ 1,150	$ 1,734
Wholesale | Real estate
Loans and Leases Receivable Disclosure [Line Items]
Retained	$ 115,737	$ 113,648
% of total criticized exposure to total real estate retained loans	0.65%	0.74%
% of criticized nonaccrual loans to total real estate retained loans	0.12%	0.12%
Wholesale | Real estate | Commercial construction and development
Loans and Leases Receivable Disclosure [Line Items]
Retained	$ 10,500	$ 10,800
Wholesale | Real estate | Multifamily
Loans and Leases Receivable Disclosure [Line Items]
Retained	$ 79,184	$ 77,597
% of total criticized exposure to total real estate retained loans	0.49%	0.63%
% of criticized nonaccrual loans to total real estate retained loans	0.07%	0.06%
Wholesale | Real estate | Other Commercial
Loans and Leases Receivable Disclosure [Line Items]
Retained	$ 36,553	$ 36,051
% of total criticized exposure to total real estate retained loans	1.00%	0.98%
% of criticized nonaccrual loans to total real estate retained loans	0.21%	0.26%
Wholesale | Real estate | Criticized exposure
Loans and Leases Receivable Disclosure [Line Items]
Retained	$ 754	$ 846
Wholesale | Real estate | Criticized exposure | Multifamily
Loans and Leases Receivable Disclosure [Line Items]
Retained	388	491
Wholesale | Real estate | Criticized exposure | Other Commercial
Loans and Leases Receivable Disclosure [Line Items]
Retained	366	355
Wholesale | Real estate | Criticized nonaccrual
Loans and Leases Receivable Disclosure [Line Items]
Retained	134	136
Wholesale | Real estate | Criticized nonaccrual | Multifamily
Loans and Leases Receivable Disclosure [Line Items]
Retained	57	44
Wholesale | Real estate | Criticized nonaccrual | Other Commercial
Loans and Leases Receivable Disclosure [Line Items]
Retained	$ 77	$ 92