Shareholders' Equity - Components of Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ 296,608	$ 263,477	$ 290,311
Other comprehensive income (loss)	(53)	8,382
Income taxes	(438)	(1,475)
Other expense, net		5,585	2,727
Income taxes	9,074	29,100	15,527
Ending Balance	335,397	296,608	263,477
Income taxes	(438)	(3,600)	(245)
Reclassification Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other expense, net		5,585
Income taxes		(2,125)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(563)	(5,115)
Other comprehensive income (loss)	(1,823)	4,552
Ending Balance	(2,386)	(563)	(5,115)
Debt Security [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	4,350	(1,465)
Other comprehensive income (loss)	1,770	3,830
Income taxes	(438)	(1,475)
Ending Balance	5,682	4,350	(1,465)
Debt Security [Member] | Reclassification Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other expense, net		5,585
Income taxes		(2,125)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	3,787	(6,580)	(6,232)
Ending Balance	$ 3,296	$ 3,787	$ (6,580)