Goodwill and Other Intangible Assets - Summary of Major Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Intangible Assets Excluding Goodwill [Line Items]
Acquired Cost	$ 966,654	$ 953,644
Accumulated Amortization	(651,180)	(583,623)
Net Intangible Assets	315,474	370,021
Client Relationships [Member]
Intangible Assets Excluding Goodwill [Line Items]
Acquired Cost	659,877	649,494
Accumulated Amortization	(482,037)	(440,163)
Net Intangible Assets	177,840	209,331
Technology & Patents [Member]
Intangible Assets Excluding Goodwill [Line Items]
Acquired Cost	181,299	178,027
Accumulated Amortization	(113,011)	(96,774)
Net Intangible Assets	68,288	81,253
Trade Names and Trademarks [Member]
Intangible Assets Excluding Goodwill [Line Items]
Acquired Cost	103,391	103,398
Accumulated Amortization	(37,331)	(30,470)
Net Intangible Assets	66,060	72,928
Other Intangible Assets [Member]
Intangible Assets Excluding Goodwill [Line Items]
Acquired Cost	22,087	22,725
Accumulated Amortization	(18,801)	(16,216)
Net Intangible Assets	$ 3,286	$ 6,509