Software and Other Intangible Assets - Carrying Amount and Accumulated Amortization of Other Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 321,864	$ 311,749
Accumulated Amortization	(130,583)	(108,115)
Net Balance	191,281	203,634
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	305,218	295,730
Accumulated Amortization	(116,677)	(96,356)
Net Balance	188,541	199,374
Trademarks and Tradenames [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	16,646	16,019
Accumulated Amortization	(13,906)	(11,759)
Net Balance	$ 2,740	$ 4,260