Premises and Equipment - Summary of Lease Costs for Operating Leases, Cash Paid Toward Lease Liabilities, and Weighted-Average Remaining Term and Discount Rates of Operating Leases (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Lease cost
Operating lease cost	$ 155	$ 154	$ 139
Short-term lease cost	0	0	8
Variable lease cost	5	4	4
Total lease cost	160	158	151
Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	101	134	138
Right-of-use assets acquired in business combination	0	0	226
Cash paid toward lease liabilities	$ 164	$ 158	$ 143
Weighted-average remaining lease term	7 years	7 years	7 years
Weighted-average discount rate	3.64%	3.37%	2.97%