Accumulated Other Comprehensive Income ("AOCI") - Summary of Total Changes in AOCI by Component, Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 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	$ (563)	$ 2,960	(10,098)	$ 11,242
Amounts reclassified from AOCI:
Amortization of defined benefit pension actuarial gain	116	50	299	205
Other comprehensive income (loss), net of tax	(447)	3,010	(9,799)	11,447
Ending Balance	246,405		246,405
Defined Benefit Pension Plan Activity [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(5,831)	(5,719)	(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	116	50	299	205
Other comprehensive income (loss), net of tax	116	50	299	205
Ending Balance	(5,715)	(5,669)	(5,715)	(5,669)
Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(50,961)	(43,213)	(41,426)	(51,495)
Other comprehensive income before reclassifications:
(Loss) gain on foreign currency translation adjustment	(563)	2,960	(10,098)	11,242
Amounts reclassified from AOCI:
Amortization of defined benefit pension actuarial gain	0	0	0	0
Other comprehensive income (loss), net of tax	(563)	2,960	(10,098)	11,242
Ending Balance	(51,524)	(40,253)	(51,524)	(40,253)
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(56,792)	(48,932)	(47,440)	(57,369)
Amounts reclassified from AOCI:
Ending Balance	$ (57,239)	$ (45,922)	$ (57,239)	$ (45,922)