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, 2023	Dec. 31, 2022	Dec. 31, 2021
Lease cost
Operating lease cost	$ 154	$ 139	$ 102
Short-term lease cost		8
Variable lease cost	4	4	4
Total lease cost	158	151	106
Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	134	138	58
Right-of-use assets acquired in business combination		226
Cash paid toward lease liabilities	$ 158	$ 143	$ 107
Weighted-average remaining lease term	7 years	7 years	6 years
Weighted-average discount rate	3.37%	2.97%	2.51%