Goodwill and Other Intangible Assets (Prior Year Acquisitions) (Pacer) (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended				12 Months Ended
	Jun. 01, 2014	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Combinations [Line Items]
Goodwill and intangible asset impairment						$ 0	$ 78,625	$ 0
Pacer [Member]
Business Combinations [Line Items]
Business combinations, effective date						Jun. 01, 2014
Business combinations, percentage of voting interests acquired						100.00%
Business combinations, name of acquired entity						Pacer Construction Holdings Corporation and its affiliated operating companies (collectively, “Pacer”)
Business combinations, description of acquired entity						Pacer, a western Canadian civil construction services company that provides infrastructure construction services in support of oil and gas production, processing, mining and transportation
Pacer [Member] | Joint Venture [Member] | Performance Guarantees [Member]
Business Combinations [Line Items]
Construction projects, percentage complete						80.00%
Pacer [Member] | Other [Member] | Joint Venture [Member] | Performance Guarantees [Member]
Business Combinations [Line Items]
Construction projects, percentage complete						80.00%
Pacer [Member] | Canadian Dollars [Member]
Business Combinations [Line Items]
Business combinations, payments in cash (in dollars)	$ 126,500
Goodwill and intangible asset impairment			$ 78,600
Pacer [Member] | Canadian Dollars [Member] | Other [Member] | Joint Venture [Member] | Contracts Accounted for under Percentage-of-Completion [Member]
Business Combinations [Line Items]
Project losses (in dollars)		$ 5,100	$ 8,000	$ 2,800	$ 5,500	$ 5,100	$ 16,300