Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Deferred tax assets:
Loan loss reserves	$ 4,455	$ 4,293
Depreciation	541	363
Other real estate owned valuation	36	65
Unrealized loss on securities available for sale		1,005
Unrealized loss on securities held to maturity		184
Interest on nonaccrual loans	375	425
Net operating loss carryforward		409
Accrued bonuses	822	840
Other	76	125
Deferred tax assets	6,305	7,709
Deferred tax liabilities:
Deferred loan fees	1,702	1,512
Federal Home Loan Bank stock dividends	437	2,749
Mortgage servicing rights	1,412	1,603
Purchase accounting adjustment	219	62
Prepaid expenses	246	228
Unrealized gain on securities available for sale	1,174
Deferred tax liabilities	5,190	6,154
Net deferred tax asset	$ 1,115	$ 1,555