Allowance for Credit Losses on Loans and Leases - Schedule of Activity in the Allowance for Loan and Lease Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 393	$ 199
Adjustment for Purchased PCD Loans	13	51
Current-period gross write-offs	223	7
Recoveries	15	11
Provision for (recovery of) credit losses on loans and leases	794	139
Ending balance	992	393
Mortgage
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning balance	290	178
Adjustment for Purchased PCD Loans		21
Current-period gross write-offs	178	5
Recoveries		4
Provision for (recovery of) credit losses on loans and leases	644	92
Ending balance	756	290
Other
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning balance	103	21
Adjustment for Purchased PCD Loans	13	30
Current-period gross write-offs	45	2
Recoveries	15	7
Provision for (recovery of) credit losses on loans and leases	150	47
Ending balance	$ 236	$ 103