Shareholders' Equity Changes in Accumulated Other Comprehensive Income (Loss) Balances (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) [Roll Forward]
Balance as of December 31, 2016			$ (83,837)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			(2,255)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	$ 10,606	$ 1,528	41,042	$ 490
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			42,089
Balance as of September 30, 2017	(44,003)		(44,003)
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2016			(84,133)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax			41,042
Balance as of September 30, 2017	(43,091)		(43,091)
Cash Flow Hedging | Foreign Exchange Contract
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2016			296
Reclassification to the statement of income			(2,255)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			1,047
Balance as of September 30, 2017	$ (912)		$ (912)