Non-performing Loans and Impaired Loans - Commercial Loans Individually Evaluated for Impairment by Class of Loans (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance total	$ 6,220	$ 6,777
Total ending loans balance	6,233	6,824
Allowance For Loan Loss Allocated	915	184
Average Balance in Impaired Loans total	6,644	7,987
Cash/Accrual Interest Income Recognized, Total	102	42
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance With no recorded allowance	5,098	5,884
Recorded Investment With no recorded allowance	5,111	5,931
Average Balance in Impaired Loans With no recorded allowance	5,519	7,087
Cash/Accrual Interest Income Recognized, With no recorded allowance	102	42
Unpaid Principal Balance With an allowance recorded	1,122
Recorded Investment With an allowance recorded	1,122
Allowance For Loan Loss Allocated	915
Average Balance in Impaired Loans With an allowance recorded	1,125
Commercial [Member] \| Owner Occupied Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance With no recorded allowance	3,275	4,038
Recorded Investment With no recorded allowance	3,269	4,063
Average Balance in Impaired Loans With no recorded allowance	3,650	4,590
Cash/Accrual Interest Income Recognized, With no recorded allowance	60	37
Unpaid Principal Balance With an allowance recorded	355	893
Recorded Investment With an allowance recorded	355	893
Allowance For Loan Loss Allocated	25	184
Average Balance in Impaired Loans With an allowance recorded	358	900
Commercial [Member] \| Non Owner Occupied Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance With no recorded allowance	840	1,033
Recorded Investment With no recorded allowance	869	1,049
Average Balance in Impaired Loans With no recorded allowance	875	975
Cash/Accrual Interest Income Recognized, With no recorded allowance	32	5
Unpaid Principal Balance With an allowance recorded	135
Recorded Investment With an allowance recorded	135
Allowance For Loan Loss Allocated	40
Average Balance in Impaired Loans With an allowance recorded	135
Commercial [Member] \| Development & Spec Land [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance With no recorded allowance	66	76
Recorded Investment With no recorded allowance	64	74
Average Balance in Impaired Loans With no recorded allowance	65	75
Commercial [Member] \| Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance With no recorded allowance	656	737
Recorded Investment With no recorded allowance	648	745
Average Balance in Impaired Loans With no recorded allowance	668	1,447
Cash/Accrual Interest Income Recognized, With no recorded allowance	7	0
Unpaid Principal Balance With an allowance recorded	632	893
Recorded Investment With an allowance recorded	632	893
Allowance For Loan Loss Allocated	850	184
Average Balance in Impaired Loans With an allowance recorded	632	$ 900
Commercial [Member] \| Residential Spec Homes [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance With no recorded allowance	261
Recorded Investment With no recorded allowance	261
Average Balance in Impaired Loans With no recorded allowance	261
Cash/Accrual Interest Income Recognized, With no recorded allowance	$ 3

Impaired financing receivable interest income accrual method and cash basis method.

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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-Publisher FASB
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