Goodwill and Intangible Assets - Schedule of Estimated Amortization Expense (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
2019	$ 257
2020	1,000
2021	978
2022	955
2023	927
Thereafter	4,493
Net Carrying Amount	8,610	$ 9,352
MSRs [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2019	22
2020	87
2021	87
2022	87
2023	86
Thereafter	1,263
Net Carrying Amount	1,632	1,664
Core deposit intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2019	235
2020	913
2021	891
2022	868
2023	841
Thereafter	3,230
Net Carrying Amount	$ 6,978	$ 7,688