Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 27,095,000		$ 27,095,000		$ 27,095,000
Change in carrying amount of goodwill			0	$ 0
Amortization of core deposit intangible assets	$ 158,000	$ 172,000	325,000	355,000
Aggregate mortgage servicing rights amortization			$ 28,000	$ 15,000