Allowance for Credit Losses and Reserve for Unfunded Lending Commitments - Summary of Loss Sharing Arrangements (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision (benefit) for credit losses	$ 1,669	$ (342)	$ 3,431	$ (2,325)
Loss sharing agreements
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Expected reimbursement from loss sharing partners, beginning balance	1,302	1,711	1,450	2,159
Financing Receivable, Allowance for Credit Loss, Writeoff	(127)	(80)	(353)	(349)
Provision (benefit) for credit losses	237	(181)	315	(360)
Expected reimbursement from loss sharing partners, ending balance	$ 1,412	$ 1,450	$ 1,412	$ 1,450