Schedule of Accumulated Other Comprehensive Income (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 [Line Items]
Beginning Balance			$ 494,644
Changes before reclassifications			20,275	$ 5,776
Current period other comprehensive income	$ 6,399	$ 3,047	20,275	5,776
Ending Balance	(77,661)		(77,661)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			(67,735)	(60,190)
Changes before reclassifications			20,900	7,955
Current period other comprehensive income			20,900	7,955
Ending Balance	(46,835)	(52,235)	(46,835)	(52,235)
Unrealized Losses of Available for Sale Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			(2,693)	(703)
Changes before reclassifications			(625)	(2,179)
Current period other comprehensive income			(625)	(2,179)
Ending Balance	(3,318)	(2,882)	(3,318)	(2,882)
AOCI Attributable to Parent
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			(70,428)	(60,893)
Ending Balance	$ (50,153)	$ (55,117)	$ (50,153)	$ (55,117)