Income Tax - Components of Income Tax Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Current tax provision	$ 4,380	$ 3,534	$ 7,887	$ 6,214
Deferred tax benefit	(312)	(733)	(1,799)	(1,537)
Income tax expense	$ 4,068	$ 2,801	$ 6,088	$ 4,677