Investments and Fair Value Measurements - Summary of Changes in Fair Value Contingent Consideration (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition, Contingent Consideration [Line Items]
Changes in valuation	$ 2,187		$ 6,813
Payments	(9,512)	$ (1,868)	(28,111)
Foreign currency adjustment	2,829		(1,444)
Fair value of contingent consideration	53,520		56,463	$ 54,796
Rialco Limited [Member]
Business Acquisition, Contingent Consideration [Line Items]
Payments	(1,300)
Fair value of contingent consideration			$ 2,109
Date of acquisition agreement			Mar. 01, 2016
Optitex Ltd [Member]
Business Acquisition, Contingent Consideration [Line Items]
Fair value of contingent consideration			$ 22,300
Date of acquisition agreement			Jun. 16, 2016
Generation Digital Solutions, Inc. [Member]
Business Acquisition, Contingent Consideration [Line Items]
Fair value of contingent consideration	$ 3,600
Date of acquisition agreement	Aug. 14, 2017