Accumulated Other Comprehensive Loss - Activity within Accumulated Other Comprehensive Loss (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	$ 654,400	$ 581,405	$ 543,694
Other comprehensive income (loss)	(22,524)	(51,693)	3,432
Ending Balance	754,917	654,400	581,405
Unrealized gain on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		22,977
Other comprehensive income (loss)		(22,977)	22,977
Ending Balance			22,977
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(71,576)	(42,860)	(23,315)
Other comprehensive income (loss)	(22,524)	(28,716)	(19,545)
Ending Balance	(94,100)	(71,576)	(42,860)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(71,576)	(19,883)	(23,315)
Other comprehensive income (loss)	(22,524)	(51,693)	3,432
Ending Balance	$ (94,100)	$ (71,576)	$ (19,883)