Allowance for Credit Losses and Reserve for Unfunded Lending Commitments - Summary of Loss Sharing Arrangements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision (benefit) for credit losses	$ 10,426	$ 5,847	$ (1,944)
Loss sharing agreements
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Expected reimbursement from loss sharing partners, beginning balance	1,558	1,450	2,159
Amounts due from partners for charged off loans	(980)	(515)	(438)
Provision (benefit) for credit losses	1,436	623	(271)
Expected reimbursement from loss sharing partners, ending balance	$ 2,014	$ 1,558	$ 1,450