Allowance for Credit Losses and Reserve for Unfunded Lending Commitments - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Uncollectible portion of billed finance charges and fees	$ 1,900	$ 946	$ 629
Allowance for credit loss	15,296	13,240
Allowance for credit losses
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase (decrease) in allowance for credit loss	2,100
Allowance for credit loss	$ 15,296	$ 13,240	$ 11,430	$ 15,564