Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Tax basis of loans in excess of financial statement basis	$ 12,010	$ 10,550
Minimum liability in defined benefit plan	352	766
Deferred compensation	2,056	1,818
Write-downs and adjustments to other real estate owned and repossessed assets	49	11
Other deferred tax assets	208	79
Total deferred tax assets	14,675	13,224
Deferred tax liabilities:
Financial statement basis of fixed assets in excess of tax basis	4,182	3,343
Intangible asset amortization deductible for tax purposes, but not for financial reporting purposes	11,263	9,926
Accretion on investment securities	745	1,039
Pension plan contributions	816	1,086
Net unrealized gain on investment securities available-for-sale	1,111	9,420
Other deferred tax liabilities	34	31
Total deferred tax liabilities	18,151	24,845
Net deferred tax asset (liability)	$ (3,476)	$ (11,621)