Loan Servicing Rights - Components of Loan Servicing Rights and Valuation Allowance (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Transfers and Servicing [Abstract]
Beginning balance	$ 25,629	$ 10,502
Additions	1,976	17,126
Amortization	(2,507)	(1,866)
Ending balance	25,098	25,762
Valuation allowance:
Beginning balance	(68)	(34)
(Additions)/recoveries	(7)	28
Ending balance	(75)	(6)
Loan servicing rights, net	$ 25,023	$ 25,756	$ 25,561