Commitments, Contingencies, Guarantees and Others - Unfunded Lending Commitments: Contractual Amount and Carrying Value (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Loss Contingencies [Line Items]
Total unfunded lending commitments, contractual amount	$ 452,558	$ 441,283
Off-balance sheet lending commitment, carrying value	92	122
Credit Card:
Loss Contingencies [Line Items]
Credit car lines, contractual amount	404,968	392,867
Other loan commitments
Loss Contingencies [Line Items]
Credit car lines, contractual amount	46,169	46,951
Off-balance sheet lending commitment, carrying value	67	99
Advised line of credit	4,500	4,700
Letter of credit
Loss Contingencies [Line Items]
Standby letters of credit and commercial letters of credit, contractual amount	1,421	1,465
Off-balance sheet lending commitment, carrying value	$ 25	$ 23