Investments and Fair Value Measurements - Summary of Changes in Fair Value Contingent Consideration (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition, Contingent Consideration [Line Items]
Changes in valuation	$ 6,472	$ 6,813
Payments	(30,924)	(28,111)
Foreign currency adjustment	2,753	(1,444)
Fair value of contingent consideration	35,702	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]
Payments	(6,800)
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
Escada [Member]
Business Acquisition, Contingent Consideration [Line Items]
Fair value of contingent consideration	$ 2,049
Date of acquisition agreement	Oct. 01, 2017
Reggiani [Member]
Business Acquisition, Contingent Consideration [Line Items]
Escrow adjustment for Reggiani acquisition	$ (4,711)
Payments	$ (21,500)	$ (23,800)