Allowance for Credit Losses on Loans - Summary of Activity in Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 57,911	$ 32,064	$ 30,616	$ 32,582	$ 32,582
Charge-offs	(491)	(293)	(1,001)	(1,019)	(3,639)
Recoveries	230	560	1,122	2,368	3,363
Provision (benefit)	22,089	537	30,089	(1,063)	(1,690)
Ending balance	79,739	32,868	79,739	32,868	30,616
Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			18,913
Ending balance					18,913
Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	29,253	12,330	11,995	12,944	12,944
Charge-offs	0	0	0	0	(746)
Recoveries	9	10	202	1,391	1,528
Provision (benefit)	15,588	(241)	20,805	(2,236)	(1,731)
Ending balance	44,850	12,099	44,850	12,099	11,995
Commercial real estate \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			11,848
Ending balance					11,848
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	19,592	10,841	10,084	11,051	11,051
Charge-offs	(277)	(155)	(407)	(362)	(770)
Recoveries	166	465	719	724	1,310
Provision (benefit)	3,684	(23)	4,485	(285)	(1,507)
Ending balance	23,165	11,128	23,165	11,128	10,084
Consumer \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			8,284
Ending balance					8,284
Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,867	5,854	4,867	5,610	5,610
Charge-offs	(214)	(138)	(594)	(657)	(2,104)
Recoveries	55	84	181	242	513
Provision (benefit)	310	681	1,525	1,286	848
Ending balance	4,018	6,481	4,018	6,481	4,867
Commercial and industrial \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			(1,961)
Ending balance					(1,961)
Construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	4,595	2,815	3,388	2,497	2,497
Charge-offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision (benefit)	2,180	81	2,454	399	891
Ending balance	6,775	2,896	6,775	2,896	3,388
Construction \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			933
Ending balance					933
Agriculture production
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	593	224	261	480	480
Charge-offs	0	0	0	0	(19)
Recoveries	0	1	20	11	12
Provision (benefit)	326	39	817	(227)	(212)
Ending balance	919	264	919	264	261
Agriculture production \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			(179)
Ending balance					(179)
Leases
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	11	0	21	0	0
Charge-offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision (benefit)	1	0	3	0	21
Ending balance	12	0	12	0	21
Leases \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			(12)
Ending balance					(12)
CRE non-owner occupied \| Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	18,034	6,268	5,948	7,401	7,401
Charge-offs	0	0	0	0	0
Recoveries	5	6	193	1,383	1,486
Provision (benefit)	8,052	(92)	13,249	(2,602)	(2,939)
Ending balance	26,091	6,182	26,091	6,182	5,948
CRE non-owner occupied \| Commercial real estate \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			6,701
Ending balance					6,701
CRE owner occupied \| Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	5,366	2,323	2,027	2,711	2,711
Charge-offs	0	0	0	0	(746)
Recoveries	4	4	9	8	42
Provision (benefit)	3,340	(113)	4,393	(505)	20
Ending balance	8,710	2,214	8,710	2,214	2,027
CRE owner occupied \| Commercial real estate \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			2,281
Ending balance					2,281
Multifamily \| Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	5,140	3,271	3,352	2,429	2,429
Charge-offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision (benefit)	3,441	(189)	2,948	653	923
Ending balance	8,581	3,082	8,581	3,082	3,352
Multifamily \| Commercial real estate \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			2,281
Ending balance					2,281
Farmland \| Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	713	468	668	403	403
Charge-offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision (benefit)	755	153	215	218	265
Ending balance	1,468	621	1,468	621	668
Farmland \| Commercial real estate \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			585
Ending balance					585
SFR 1-4 1st DT Liens \| Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	5,650	2,500	2,306	2,676	2,676
Charge-offs	(11)	(2)	(11)	(2)	(2)
Recoveries	2	3	412	5	54
Provision (benefit)	2,374	75	2,633	(103)	(422)
Ending balance	8,015	2,576	8,015	2,576	2,306
SFR 1-4 1st DT Liens \| Consumer \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			2,675
Ending balance					2,675
SFR HELOCs and junior liens \| Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	11,196	7,301	6,183	7,582	7,582
Charge-offs	(23)	0	(23)	0	(3)
Recoveries	92	354	140	536	935
Provision (benefit)	843	(554)	1,170	(1,017)	(2,331)
Ending balance	12,108	7,101	12,108	7,101	6,183
SFR HELOCs and junior liens \| Consumer \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			4,638
Ending balance					4,638
Other \| Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,746	1,040	1,595	793	793
Charge-offs	(243)	(153)	(373)	(360)	(765)
Recoveries	72	108	167	183	321
Provision (benefit)	467	456	682	835	1,246
Ending balance	$ 3,042	$ 1,451	3,042	$ 1,451	1,595
Other \| Consumer \| Impact of CECL Adoption
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			$ 971
Ending balance					$ 971

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- Definition

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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Amount of writeoff of financing receivable, charged against allowance for credit loss.

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Amount of credit loss expense (reversal of expense) for financing receivable.

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