Loans and Lease Finance Receivables and Allowance for Credit Losses - Summary of Components of Loans and Lease Finance Receivables, Including PCI Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	$ 8,680,221		$ 7,879,537
Construction	60,584		62,264
Total	8,692,229		7,887,713
Less: Allowance for credit losses	(80,222)	$ (76,119)	(65,019)	$ (69,342)	$ (71,805)	$ (93,692)
Net loans and lease finance receivables	8,612,007		7,822,694
Commercial And Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	941,595		813,063
Total	941,595		813,063
SBA [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	297,109		288,600
Total	297,109		288,600
SBA - Paycheck Protection Program (PPP) [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	66,955		186,585
Total	66,955		186,585
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	6,643,628		5,789,730
SFR mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	260,218		240,654
Total	260,218		240,654
Dairy And Livestock And Agribusiness [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	273,594		386,219
Total	273,594		386,219
Municipal Lease Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	64,437		45,933
Total	64,437		45,933
Less: Allowance for credit losses	(183)	$ (152)	(100)	$ (67)	$ (35)	$ (74)
Consumer and other loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable gross	84,109		74,665
Total	$ 84,109		$ 74,665