Segment Information, Geographic Regions, and Major Customers - Revenue by Ship-to Destination (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total revenue	$ 269,163	$ 248,359	$ 247,047	$ 228,691	$ 266,707	$ 245,575	$ 245,650	$ 234,133	$ 993,260	$ 992,065	$ 882,513
Americas [Member]
Segment Reporting Information [Line Items]
Total revenue									487,968	500,411	473,599
Europe, Middle East, and Africa ("EMEA") [Member]
Segment Reporting Information [Line Items]
Total revenue									369,610	360,305	291,103
Asia Pacific ("APAC") [Member]
Segment Reporting Information [Line Items]
Total revenue									$ 135,682	$ 131,349	$ 117,811