Changes in Balances of Accumulated Other Comprehensive (Loss) Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 1,158,445	$ 947,830	$ 722,546
Other comprehensive (loss) income before reclassifications	(19,106)	(45,162)	(25,899)
Amounts reclassified from accumulated other comprehensive (loss)income	(190)	(4,203)	(3,042)
Out-of-period adjustment			(3,000)
Net current-period other comprehensive (loss)/income	(19,296)	(49,365)	(31,941)
Ending balance	(183,087)	1,158,445	947,830
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(235,146)	(189,410)	(157,416)
Other comprehensive (loss) income before reclassifications	(19,064)	(45,736)	(28,994)
Out-of-period adjustment			(3,000)
Net current-period other comprehensive (loss)/income	(19,064)	(45,736)	(31,994)
Ending balance	(254,210)	(235,146)	(189,410)
Unrealized Gains (losses) on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	332	4,600	3,808
Other comprehensive (loss) income before reclassifications	161	50	3,853
Amounts reclassified from accumulated other comprehensive (loss)income	(165)	(4,318)	(3,061)
Net current-period other comprehensive (loss)/income	(4)	(4,268)	792
Ending balance	328	332	4,600
Defined Benefit Pension Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(795)	(1,434)	(695)
Other comprehensive (loss) income before reclassifications	(525)	524	(758)
Amounts reclassified from accumulated other comprehensive (loss)income	(25)	115	19
Net current-period other comprehensive (loss)/income	(550)	639	(739)
Ending balance	(1,345)	(795)	(1,434)
Unrealised Gain on Derivatives Designated as Cash Flow Hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive (loss) income before reclassifications	322
Net current-period other comprehensive (loss)/income	322
Ending balance	322
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(235,609)	(186,244)	(154,303)
Net current-period other comprehensive (loss)/income	(19,296)	(49,365)	(31,941)
Ending balance	$ (254,905)	$ (235,609)	$ (186,244)