Goodwill and Intangibles - Summary of Other Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 33,024	$ 32,504
Accumulated Amortization	(13,008)	(10,067)
Net Intangible Assets	20,016	22,437
Core deposits
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	10,658	10,658
Accumulated Amortization	(5,285)	(4,263)
Net Intangible Assets	$ 5,373	$ 6,395
Amortization Period	10 years	10 years
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 17,561	$ 17,561
Accumulated Amortization	(5,815)	(4,214)
Net Intangible Assets	$ 11,746	$ 13,347
Customer relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization Period	7 years	7 years
Customer relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization Period	15 years	15 years
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 221	$ 221
Accumulated Amortization	(101)	(57)
Net Intangible Assets	$ 120	$ 164
Amortization Period	5 years	5 years
Loan servicing rights
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 2,652	$ 2,132
Accumulated Amortization	(1,301)	(1,191)
Net Intangible Assets	$ 1,351	$ 941
Loan servicing rights | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization Period	10 years	10 years
Loan servicing rights | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization Period	30 years	30 years
Favorable lease asset
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 1,932	$ 1,932
Accumulated Amortization	(506)	(342)
Net Intangible Assets	$ 1,426	$ 1,590
Favorable lease asset | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization Period	10 months	10 months
Favorable lease asset | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization Period	18 years	15 years