Commitments and Contingent Liabilities - Commitments to Extend Credit, Guarantees and Various Letters of Credit Outstanding (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Lines of credit	$ 2,504,347	$ 2,510,011
Loans approved but not closed	517,071	381,180
Overdraft limits	152,302	154,322
Letters of credit	50,423	53,788
Contingent obligations and other guarantees	$ 176,244	$ 126,984