Accumulated Other Comprehensive Income ("AOCI") - Summary of Total Changes in AOCI by Component, Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ 238,537
Other comprehensive income before reclassifications:
(Loss) gain on foreign currency translation adjustment	$ (13,367)	$ 2,810	(9,535)	$ 8,282
Amounts reclassified from AOCI:
Amortization of defined benefit pension actuarial gain (loss)	92	83	183	155
Other comprehensive income (loss), net of tax	(13,275)	2,893	(9,352)	8,437
Ending Balance	239,529		239,529
Defined Benefit Pension Plan Activity [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(5,923)	(5,802)	(6,014)	(5,874)
Other comprehensive income before reclassifications:
(Loss) gain on foreign currency translation adjustment	0	0	0	0
Amounts reclassified from AOCI:
Amortization of defined benefit pension actuarial gain (loss)	92	83	183	155
Other comprehensive income (loss), net of tax	92	83	183	155
Ending Balance	(5,831)	(5,719)	(5,831)	(5,719)
Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(37,594)	(46,023)	(41,426)	(51,495)
Other comprehensive income before reclassifications:
(Loss) gain on foreign currency translation adjustment	(13,367)	2,810	(9,535)	8,282
Amounts reclassified from AOCI:
Amortization of defined benefit pension actuarial gain (loss)	0	0	0	0
Other comprehensive income (loss), net of tax	(13,367)	2,810	(9,535)	8,282
Ending Balance	(50,961)	(43,213)	(50,961)	(43,213)
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(43,517)	(51,825)	(47,440)	(57,369)
Amounts reclassified from AOCI:
Ending Balance	$ (56,792)	$ (48,932)	$ (56,792)	$ (48,932)