Other Intangible Assets, Net - Carrying Amount of Other Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Gross amount	$ 637,570	$ 607,211
Accumulated amortization	(357,609)	(308,092)
Net carrying amount	279,961	299,119
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross amount	344,175	334,455
Accumulated amortization	(168,134)	(141,829)
Net carrying amount	$ 176,041	$ 192,626
Customer relationships | Minimum
Acquired Finite-Lived Intangible Assets [Line Items]
Useful life in years	8 years	8 years
Customer relationships | Maximum
Acquired Finite-Lived Intangible Assets [Line Items]
Useful life in years	14 years	14 years
Trademark
Acquired Finite-Lived Intangible Assets [Line Items]
Gross amount	$ 41,594	$ 39,950
Accumulated amortization	(25,241)	(21,650)
Net carrying amount	$ 16,353	$ 18,300
Trademark | Minimum
Acquired Finite-Lived Intangible Assets [Line Items]
Useful life in years	2 years	10 years
Trademark | Maximum
Acquired Finite-Lived Intangible Assets [Line Items]
Useful life in years	15 years	15 years
Software packages
Acquired Finite-Lived Intangible Assets [Line Items]
Gross amount	$ 195,262	$ 176,267
Accumulated amortization	(136,907)	(121,055)
Net carrying amount	$ 58,355	$ 55,212
Software packages | Minimum
Acquired Finite-Lived Intangible Assets [Line Items]
Useful life in years	3 years	3 years
Software packages | Maximum
Acquired Finite-Lived Intangible Assets [Line Items]
Useful life in years	10 years	10 years
Non-compete agreement
Acquired Finite-Lived Intangible Assets [Line Items]
Useful life in years	15 years	15 years
Gross amount	$ 56,539	$ 56,539
Accumulated amortization	(27,327)	(23,558)
Net carrying amount	$ 29,212	$ 32,981