Goodwill and Intangibles - Intangible Assets and Accumulated Amortization Balances (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 161,118	$ 164,645
Accumulated Amortization	(92,027)	(83,282)
Net Carrying Amount	69,091	81,363
Customer relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	135,927	134,918
Accumulated Amortization	(86,342)	(73,088)
Net Carrying Amount	49,585	61,830
Developed technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,893	8,762
Accumulated Amortization	(2,893)	(8,386)
Net Carrying Amount	0	376
Other [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	22,298	20,965
Accumulated Amortization	(2,792)	(1,808)
Net Carrying Amount	$ 19,506	$ 19,157