Goodwill and Other Intangible Assets - Summary of Major Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Intangible Assets Excluding Goodwill [Line Items]
Acquired Cost	$ 962,606	$ 953,644
Accumulated Amortization	(619,867)	(583,623)
Net Intangible Assets	342,739	370,021
Client Relationships [Member]
Intangible Assets Excluding Goodwill [Line Items]
Acquired Cost	656,459	649,494
Accumulated Amortization	(463,933)	(440,163)
Net Intangible Assets	192,526	209,331
Technology & Patents [Member]
Intangible Assets Excluding Goodwill [Line Items]
Acquired Cost	179,370	178,027
Accumulated Amortization	(104,087)	(96,774)
Net Intangible Assets	75,283	81,253
Trade Names and Trademarks (Finite-Lived) [Member]
Intangible Assets Excluding Goodwill [Line Items]
Acquired Cost	103,555	103,398
Accumulated Amortization	(34,297)	(30,470)
Net Intangible Assets	69,258	72,928
Other Intangible Assets [Member]
Intangible Assets Excluding Goodwill [Line Items]
Acquired Cost	23,222	22,725
Accumulated Amortization	(17,550)	(16,216)
Net Intangible Assets	$ 5,672	$ 6,509