Loans - Summary of Loan Balances (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Loans and Leases Receivable Disclosure [Line Items]
Total	$ 4,944,894		$ 4,763,127
Total principal balance of loans owed, net of charge-offs	4,984,824		4,805,596
Unamortized net deferred loan fees	(19,843)		(16,984)
Discounts to principal balance of loans owed, net of charge-offs	(20,087)		(25,485)
Allowance for loan losses	(86,062)	$ (85,941)	(91,847)	$ (79,739)	$ (57,911)	$ (30,616)
Commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Total	3,194,336		2,951,902
Allowance for loan losses	(51,637)	(50,403)	(53,693)	(44,850)	(29,253)	(11,995)
Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total	1,050,609		952,108
Allowance for loan losses	(23,950)	(24,604)	(25,148)	(23,165)	(19,592)	(10,084)
Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Total	452,069		526,327
Allowance for loan losses	(4,511)	(4,464)	(4,252)	(4,018)	(3,867)	(4,867)
Construction
Loans and Leases Receivable Disclosure [Line Items]
Total	200,714		284,842
Allowance for loan losses	(4,951)	(5,476)	(7,540)	(6,775)	(4,595)	(3,388)
Agriculture production
Loans and Leases Receivable Disclosure [Line Items]
Total	41,967		44,164
Allowance for loan losses	(1,007)	(988)	(1,209)	(919)	(593)	(261)
Leases
Loans and Leases Receivable Disclosure [Line Items]
Total	5,199		3,784
Allowance for loan losses	(6)	(6)	(5)	(12)	(11)	(21)
CRE non-owner occupied | Commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Total	1,534,256		1,535,555
Allowance for loan losses	(26,028)	(26,434)	(29,380)	(26,091)	(18,034)	(5,948)
CRE owner occupied | Commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Total	659,948		624,375
Allowance for loan losses	(10,463)	(9,874)	(10,861)	(8,710)	(5,366)	(2,027)
Multifamily | Commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Total	828,101		639,480
Allowance for loan losses	(13,196)	(12,371)	(11,472)	(8,581)	(5,140)	(3,352)
Farmland | Commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Total	172,031		152,492
Allowance for loan losses	(1,950)	(1,724)	(1,980)	(1,468)	(713)	(668)
SFR 1-4 1st DT liens | Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total	654,373		546,592
SFR HELOCs and junior liens | Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total	325,127		327,484
Allowance for loan losses	(10,701)	(11,079)	(11,771)	(12,108)	(11,196)	(6,183)
Other | Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total	71,109		78,032
Allowance for loan losses	$ (2,620)	$ (2,860)	$ (3,260)	$ (3,042)	$ (2,746)	$ (1,595)