Acquisitions (Allocation of Purchase Price) (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Mar. 13, 2015	Jan. 13, 2015	Dec. 31, 2014	Dec. 30, 2014	Oct. 29, 2014	Jul. 07, 2014
Business Acquisition [Line Items]
Goodwill		$ 81,202			$ 82,949
Inspection Oilfield Services (IOS) [Member]
Business Acquisition [Line Items]
Current assets			$ 19,877
Other assets			708
Property, plant and equipment			51,453
Goodwill	[1]		69,908
Other intangibles			50,354
Liabilities assumed			(23,596)
Total			$ 168,704
Tew Holdings, LTD [Member]
Business Acquisition [Line Items]
Current assets				$ 12,125
Other assets				0
Property, plant and equipment				2,398
Goodwill				8,772
Other intangibles				14,048
Liabilities assumed				(6,465)
Total				$ 30,878
Chemtec Energy Services, LLC [Member]
Business Acquisition [Line Items]
Current assets						$ 15,528
Other assets						0
Property, plant and equipment						4,705
Goodwill	[1]					22,302
Other intangibles						33,130
Liabilities assumed						(6,756)
Total						$ 68,909
FWO [Member]
Business Acquisition [Line Items]
Current assets							$ 131
Other assets							0
Property, plant and equipment							0
Goodwill							971
Other intangibles							419
Liabilities assumed							(418)
Total							$ 1,103
Carr Concrete [Member]
Business Acquisition [Line Items]
Current assets								$ 3,180
Other assets								45
Property, plant and equipment								7,648
Goodwill								1,936
Other intangibles								1,348
Liabilities assumed								(1,677)
Total								$ 12,480

[1] See Note 4 with respect to an impairment of the goodwill related to this acquisition.