Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Loan loss reserves	$ 6,460	$ 6,680
Depreciation	828	748
Other real estate owned valuation	192	354
Tax credits carryforward	1,736	1,471
Unrealized loss on securities available for sale	1,165	1,685
Unrealized loss on securities held to maturity	413	431
Interest on nonaccrual loans	980	1,039
Net operating loss carryforward	9,672	8,574
Purchase accounting adjustment	1,353
Accrued bonuses	574	812
Other	152	221
Deferred tax assets	23,525	22,015
Deferred tax liabilities:
Deferred loan fees	1,437	1,275
Federal Home Loan Bank stock dividends	4,645	4,585
Mortgage servicing rights	2,091	2,124
FHLB prepayment penalty	717	786
Purchase accounting adjustment		371
Prepaid expenses	171	139
Deferred tax liabilities	9,061	9,280
Net deferred tax asset	$ 14,464	$ 12,735