Loans, Lending Commitments and Related Allowance for Credit Losses - Past Due Loans Held for Investment before Allowance (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 219,116	$ 204,554
Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	416	393
Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	6,304	6,758
Corporate | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	0	47
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	8,688	8,678
Commercial real estate | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	182	185
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	65,001	60,375
Residential real estate | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	147	160
Securities-based lending and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	93,395	89,245
Securities-based lending and Other | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 87	$ 1