Acquisitions (Identifiable Intangible Assets Acquired) (Details) - USD ($) $ in Thousands	Mar. 13, 2015	Jan. 13, 2015	Dec. 30, 2014	Oct. 29, 2014	Jul. 07, 2014
Inspection Oilfield Services (IOS) [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets	$ 50,354
Inspection Oilfield Services (IOS) [Member] | Trade name [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets	2,641
Inspection Oilfield Services (IOS) [Member] | Customer relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets	41,171
Inspection Oilfield Services (IOS) [Member] | Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets	4,364
Inspection Oilfield Services (IOS) [Member] | Non-compete agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets	$ 2,178
Tew Holdings, LTD [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets		$ 14,048
Tew Holdings, LTD [Member] | Trade name [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets		870
Tew Holdings, LTD [Member] | Customer relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets		10,035
Tew Holdings, LTD [Member] | Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets		2,480
Tew Holdings, LTD [Member] | Non-compete agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets		$ 663
Chemtec Energy Services, LLC [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets			$ 33,130
Chemtec Energy Services, LLC [Member] | Trade name [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets			3,149
Chemtec Energy Services, LLC [Member] | Customer relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets			23,934
Chemtec Energy Services, LLC [Member] | Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets			4,930
Chemtec Energy Services, LLC [Member] | Non-compete agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets			$ 1,117
FWO [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets				$ 419
FWO [Member] | Trade name [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets				0
FWO [Member] | Customer relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets				34
FWO [Member] | Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets				341
FWO [Member] | Non-compete agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets				$ 44
Carr Concrete [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets					$ 1,348
Carr Concrete [Member] | Trade name [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets					613
Carr Concrete [Member] | Customer relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets					524
Carr Concrete [Member] | Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets					87
Carr Concrete [Member] | Non-compete agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value estimate of acquired identifiable intangible assets					$ 124