Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Loan loss reserves	$ 4,319	$ 4,293
Depreciation	426	363
Other real estate owned valuation	67	65
Unrealized loss on securities available for sale	208	1,005
Unrealized loss on securities held to maturity	177	184
Interest on nonaccrual loans	414	425
Net operating loss carryforward		409
Accrued bonuses	566	840
Other	47	125
Deferred tax assets	6,224	7,709
Deferred tax liabilities:
Deferred loan fees	1,525	1,512
Federal Home Loan Bank stock dividends	2,236	2,749
Mortgage servicing rights	1,569	1,603
Purchase accounting adjustment	167	62
Prepaid expenses	235	228
Deferred tax liabilities	5,732	6,154
Net deferred tax asset	$ 492	$ 1,555