Acquisitions (Contingent Consideration of Obligations Related to Previous Acquisitions) (Detail) (R360 Environmental Solutions Inc [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Oct. 25, 2012	Nov. 30, 2012
Business Acquisition [Line Items]
Contingent consideration	$ 37,293	$ 37,293
Prairie Disposal [Member]
Business Acquisition [Line Items]
Contingent consideration	24,376
Oilfield Holdings [Member]
Business Acquisition [Line Items]
Contingent consideration	8,000		8,000
Calpet [Member]
Business Acquisition [Line Items]
Contingent consideration	4,176
Claco Services [Member]
Business Acquisition [Line Items]
Contingent consideration	$ 741