Loans and Lease Finance Receivables and Allowance for Credit Losses - Schedule of Recorded Investment in, and Aging of, Past Due and Nonaccrual Loans, Including PCI Loans by Class of Loans (Detail) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	$ 12,008,000	$ 8,176,000
Nonaccrual	12,964,000	6,893,000
Nonaccrual with No Allowance for Credit Losses	(6,189,000)	5,992,000
Loans Not Past Due	8,680,221,000	7,879,537,000
Loans Past Due Over 89 Days Still Accruing	0	0
Total loans	8,692,229,000	7,887,713,000
30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	83,000	1,895,000
Nonaccrual	83,000	332,000
60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	916,000	1,161,000
Nonaccrual	357,000	267,000
Greater than 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	11,009,000	5,120,000
Nonaccrual	11,000,000.0	5,100,000
Commercial Real Estate Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	6,297,000	3,821,000
Nonaccrual	6,823,000	3,607,000
Nonaccrual with No Allowance for Credit Losses	(3,823,000)	3,607,000
Loans Not Past Due	2,464,612,000	2,127,979,000
Loans Past Due Over 89 Days Still Accruing	0	0
Total loans	2,470,909,000	2,131,800,000
Commercial Real Estate Owner Occupied [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		438,000
Commercial Real Estate Owner Occupied [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Commercial Real Estate Owner Occupied [Member] | Greater than 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	6,297,000	3,383,000
Commercial Real Estate Non-owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	579,000
Nonaccrual	20,000	0
Nonaccrual with No Allowance for Credit Losses	(20,000)	0
Loans Not Past Due	4,172,140,000	3,657,930,000
Loans Past Due Over 89 Days Still Accruing	0	0
Total loans	4,172,719,000	3,657,930,000
Commercial Real Estate Non-owner Occupied [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Commercial Real Estate Non-owner Occupied [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	559,000
Commercial Real Estate Non-owner Occupied [Member] | Greater than 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	20,000
Construction Speculative [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Nonaccrual		0
Nonaccrual with No Allowance for Credit Losses		0
Loans Not Past Due	49,732,000	44,859,000	[1]
Loans Past Due Over 89 Days Still Accruing	0	0
Total loans	49,732,000	44,859,000	[1]
Construction Speculative [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Construction Speculative [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Construction Speculative [Member] | Greater than 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Construction Non-speculative [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Nonaccrual		0
Nonaccrual with No Allowance for Credit Losses		0
Loans Not Past Due	10,852,000	17,405,000
Loans Past Due Over 89 Days Still Accruing	0	0
Total loans	10,852,000	17,405,000
Construction Non-speculative [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Construction Non-speculative [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Construction Non-speculative [Member] | Greater than 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Small Business Administration [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	877,000	1,901,000
Nonaccrual	1,075,000	1,034,000
Nonaccrual with No Allowance for Credit Losses	(349,000)	521,000
Loans Not Past Due	296,232,000	286,699,000
Loans Past Due Over 89 Days Still Accruing	0	0
Total loans	297,109,000	288,600,000
Small Business Administration [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	83,000	417,000
Small Business Administration [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		1,145,000
Small Business Administration [Member] | Greater than 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	794,000	339,000
SBA - Paycheck Protection Program (PPP) [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Nonaccrual		0
Nonaccrual with No Allowance for Credit Losses		0
Loans Not Past Due	66,955,000	186,585,000
Loans Past Due Over 89 Days Still Accruing	0	0
Total loans	66,955,000	186,585,000
SBA - Paycheck Protection Program (PPP) [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
SBA - Paycheck Protection Program (PPP) [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
SBA - Paycheck Protection Program (PPP) [Member] | Greater than 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	1,012,000	1,372,000
Nonaccrual	1,655,000	1,714,000
Nonaccrual with No Allowance for Credit Losses	(1,130,000)	1,326,000
Loans Not Past Due	940,583,000	811,691,000
Loans Past Due Over 89 Days Still Accruing	0	0
Total loans	941,595,000	813,063,000
Commercial and Industrial [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Commercial and Industrial [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	357,000	16,000
Commercial and Industrial [Member] | Greater than 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	655,000	1,356,000
Dairy & Livestock and Agribusiness [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	3,206,000
Nonaccrual	3,354,000	0
Nonaccrual with No Allowance for Credit Losses	(830,000)	0
Loans Not Past Due	270,388,000	386,219,000
Loans Past Due Over 89 Days Still Accruing	0	0
Total loans	273,594,000	386,219,000
Dairy & Livestock and Agribusiness [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Dairy & Livestock and Agribusiness [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Dairy & Livestock and Agribusiness [Member] | Greater than 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	3,206,000
Municipal Lease Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Nonaccrual		0
Nonaccrual with No Allowance for Credit Losses
Loans Not Past Due	64,437,000	45,933,000
Loans Past Due Over 89 Days Still Accruing	0	0
Total loans	64,437,000	45,933,000
Municipal Lease Finance Receivables [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Municipal Lease Finance Receivables [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Municipal Lease Finance Receivables [Member] | Greater than 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
SFR Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		1,040,000
Nonaccrual		380,000
Nonaccrual with No Allowance for Credit Losses
Loans Not Past Due	260,218,000	239,614,000
Loans Past Due Over 89 Days Still Accruing	0	0
Total loans	260,218,000	240,654,000
SFR Mortgage [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due		1,040,000
SFR Mortgage [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
SFR Mortgage [Member] | Greater than 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Consumer and Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	37,000	42,000
Nonaccrual	37,000	158,000
Nonaccrual with No Allowance for Credit Losses	(37,000)	158,000
Loans Not Past Due	84,072,000	74,623,000
Loans Past Due Over 89 Days Still Accruing	0	0
Total loans	84,109,000	74,665,000
Consumer and Other Loans [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Consumer and Other Loans [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due
Consumer and Other Loans [Member] | Greater than 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Past Due	$ 37,000	$ 42,000

[1] Speculative construction loans are generally for properties where there is no identified buyer or renter.