Loans, Lending Commitments and Related Allowance for Credit Losses - Nonaccrual Loans Held for Investment before Allowance (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 591	$ 483
Nonaccrual loans without an ACL	90	120
Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	164	299
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	152	85
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	97	94
Securities-based lending and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 178	$ 5