Shareholders' Equity Changes in Accumulated Other Comprehensive Income (Loss) Balances (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) [Roll Forward]
Balance as of December 31, 2017			$ (45,629)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			(6,945)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	$ 1,804	$ 10,606	(12,099)	$ 41,042
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(1,960)
Balance as of September 30, 2018	(54,534)		(54,534)
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2017			(42,442)
Balance as of September 30, 2018	(54,541)		(54,541)
Cash Flow Hedging | Foreign Exchange Contract
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2017			(34)
Reclassification to the statement of income			(7,141)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			10,139
Balance as of September 30, 2018	2,964		2,964
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2017			(3,153)
Reclassification to the statement of income			196
Balance as of September 30, 2018	$ (2,957)		$ (2,957)