Loan Servicing - Summary of Activity In Company's Mortgage Servicing Rights (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Mortgage servicing rights:
Balance at beginning of year	$ 2,601	$ 2,445
Additions through originations	2,348	642
Acquisition of First Eastern	6,216
Amortization	(1,064)	(486)
Sales	(1,191)
Balance at end of year	8,910	2,601
Valuation allowance:
Balance at beginning of year	34
Provision	390	34
Balance at end of year	424	34
Mortgage servicing rights, amortized cost	8,486	2,567
Mortgage servicing rights, fair value	$ 8,520	$ 2,981