Acquisitions (Narrative) (Details) - USD ($) $ in Thousands							12 Months Ended
	Nov. 23, 2015	Mar. 13, 2015	Jan. 13, 2015	Dec. 30, 2014	Oct. 29, 2014	Jul. 07, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired							$ 0	$ 196,001	$ 80,797
Business Acquisition, Transaction Costs							$ 760	$ 2,240
TEW Plus LTD [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Nov. 23, 2015
Business Acquisition, Name of Acquired Entity	TEW Plus, Ltd ("Tew Plus")
Payments to Acquire Businesses, Net of Cash Acquired	$ 2,130
Inspection Oilfield Services (IOS) [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition		Mar. 13, 2015
Business Acquisition, Name of Acquired Entity		IOS Holdings, Inc. ("IOS")
Payments to Acquire Businesses, Net of Cash Acquired		$ 167,404
Working capital adjustment		2,363
Earn out provision		60,000
Business Combination, Indemnification Assets, Amount as of Acquisition Date		$ 7,600
TEW Holdings, LTD [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition			Jan. 13, 2015
Business Acquisition, Name of Acquired Entity			TEW Holdings, Ltd ("Tew")
Payments to Acquire Businesses, Net of Cash Acquired			$ 26,467
Working capital adjustment			4,200
Business Combination, Indemnification Assets, Amount as of Acquisition Date			$ 600
Chemtec Energy Services, LLC [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition				Dec. 30, 2014
Business Acquisition, Name of Acquired Entity				Chemtec Energy Services, LLC ("Chemtec")
Payments to Acquire Businesses, Net of Cash Acquired				$ 66,719
Working capital adjustment				1,867
Business Combination, Indemnification Assets, Amount as of Acquisition Date				$ 5,000
FWO [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition					Oct. 29, 2014
Business Acquisition, Name of Acquired Entity					FWO
Payments to Acquire Businesses, Net of Cash Acquired					$ 1,103
Working capital adjustment					$ 161
Carr Concrete [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition						Jul. 07, 2014
Business Acquisition, Name of Acquired Entity						Carr Concrete Corporation ("Carr")
Payments to Acquire Businesses, Net of Cash Acquired						$ 12,480
Working capital adjustment						189
Business Combination, Indemnification Assets, Amount as of Acquisition Date						$ 1,000