Segment Information and Geographic Data - Revenue by Ship-to Destination (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Total revenue	$ 239,866	$ 228,691
Americas [Member]
Segment Reporting Information [Line Items]
Total revenue	117,385	109,895
Europe, Middle East, and Africa ("EMEA") [Member]
Segment Reporting Information [Line Items]
Total revenue	88,175	88,033
Asia Pacific ("APAC") [Member]
Segment Reporting Information [Line Items]
Total revenue	$ 34,306	$ 30,763