Accumulated Other Comprehensive Loss - Components of Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			$ 263,477
Other comprehensive income (loss)			773
Income taxes			1,223
Other expense, net	$ 479	$ (634)	(3,284)	$ 1,346
Income taxes	6,150	$ (1,276)	13,998	$ 6,703
Ending Balance	285,311		285,311
Reclassification Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other expense, net			5,585
Income taxes			(2,123)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			(5,115)
Other comprehensive income (loss)			3,993
Ending Balance	(1,122)		(1,122)
Debt Security [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			(1,465)
Other comprehensive income (loss)			(3,220)
Income taxes			1,223
Debt Security [Member] | Reclassification Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other expense, net			5,585
Income taxes			(2,123)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			(6,580)
Ending Balance	$ (221)		$ (221)