Loans - Summary of Loans Individually Evaluated for Impairment by Class of Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Impaired [Line Items]
Total impaired loans, excluding PCD loans	$ 30,995	$ 26,140
Amount of allowance for credit losses allocated to impaired loans		1,878
Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans, excluding PCD loans		6,475
Amount of allowance for credit losses allocated to impaired loans		588
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans, excluding PCD loans		11,445
Amount of allowance for credit losses allocated to impaired loans		375
Land, Development, Construction [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans, excluding PCD loans		865
Consumer and Other [Member]
Financing Receivable, Impaired [Line Items]
Total impaired loans, excluding PCD loans		123
Amount of allowance for credit losses allocated to impaired loans		1
Non-PCD Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid principal balance	33,203	28,307
Total impaired loans, excluding PCD loans	30,995
Amount of allowance for credit losses allocated to impaired loans	1,920
Non-PCD Loans [Member] \| Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Unpaid principal balance, With no allowance recorded	2,822	2,894
Unpaid principal balance, With an allowance recorded	2,126	3,920
Recorded investment, With no related allowance	2,669	2,744
Recorded investment, With an allowance recorded	1,990	3,731
Amount of allowance for credit losses allocated to impaired loans	322	588
Non-PCD Loans [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Unpaid principal balance, With no allowance recorded	16,470	11,031
Unpaid principal balance, With an allowance recorded	3,175	1,438
Recorded investment, With no related allowance	15,003	10,015
Recorded investment, With an allowance recorded	3,142	1,430
Amount of allowance for credit losses allocated to impaired loans	280	375
Non-PCD Loans [Member] \| Land, Development, Construction [Member]
Financing Receivable, Impaired [Line Items]
Unpaid principal balance, With no allowance recorded	755	886
Unpaid principal balance, With an allowance recorded	56
Recorded investment, With no related allowance	725	865
Recorded investment, With an allowance recorded	56
Amount of allowance for credit losses allocated to impaired loans	4
Non-PCD Loans [Member] \| Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Unpaid principal balance, With no allowance recorded	3,737	5,522
Unpaid principal balance, With an allowance recorded	3,922	2,486
Recorded investment, With no related allowance	3,424	4,820
Recorded investment, With an allowance recorded	3,852
Amount of allowance for credit losses allocated to impaired loans	1,314
Non-PCD Loans [Member] \| Consumer and Other [Member]
Financing Receivable, Impaired [Line Items]
Unpaid principal balance, With no allowance recorded	110	99
Unpaid principal balance, With an allowance recorded	30	31
Recorded investment, With no related allowance	109	$ 98
Recorded investment, With an allowance recorded	25
PCD Loans [Member]
Financing Receivable, Impaired [Line Items]
Unpaid principal balance	40,744
Total impaired loans, excluding PCD loans	22,776
Amount of allowance for credit losses allocated to impaired loans	12,315
PCD Loans [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Unpaid principal balance, With an allowance recorded	35,999
Recorded investment, With an allowance recorded	19,611
Amount of allowance for credit losses allocated to impaired loans	9,917
PCD Loans [Member] \| Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Unpaid principal balance, With an allowance recorded	4,745
Recorded investment, With an allowance recorded	3,165
Amount of allowance for credit losses allocated to impaired loans	$ 2,398

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
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