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 Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lease cost
Operating lease cost	$ 104,158	$ 100,669
Short-term lease cost	198	105
Variable lease cost	1,565	2,332
Total lease cost	105,921	103,106
Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	70,754	132,219
Cash paid toward lease liabilities	$ 104,396	$ 101,869
Weighted-average remaining lease term	7 years	7 years
Weighted-average discount rate	2.74%	3.01%