Loan Servicing Rights - Components of Loan Servicing Rights and Valuation Allowance (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Transfers and Servicing [Abstract]
Beginning balance	$ 25,629	$ 10,502
Additions	1,041	481
Amortization	(1,174)	(447)
Ending balance	25,496	10,536
Valuation allowance:
Beginning balance	(68)	(34)
(Additions)/recoveries	18	32
Ending balance	(50)	(2)
Loan servicing rights, net	$ 25,446	$ 10,534	$ 25,561