Software and Other Intangible Assets - Carrying Amount and Accumulated Amortization of Other Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 325,331	$ 321,864
Accumulated Amortization	(136,643)	(130,583)
Net Balance	188,688	191,281
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	308,489	305,218
Accumulated Amortization	(122,164)	(116,677)
Net Balance	186,325	188,541
Trademarks and Tradenames [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	16,842	16,646
Accumulated Amortization	(14,479)	(13,906)
Net Balance	$ 2,363	$ 2,740