Business, Basis of Presentation and Significant Accounting Policies (Restatement of Previously Reported Condensed Unaudited Consolidated Financial Statements) (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue	$ 1,003,268	$ 957,818
Costs of revenue, excluding depreciation and amortization	886,414	841,324
Other income, net	7	2,083
Provision for income taxes	(4,352)	$ 7,489
Other current liabilities	43,373		$ 66,527
Costs and earnings in excess of billings	436,300		485,600
Acquisition-related contingent consideration, net of current portion	99,516		103,515
Acquisition-related contingent consideration, current	$ 49,177		$ 49,798
Basic earnings per share, continuing operations (in dollars per share)	$ (0.08)	$ 0.16
Diluted earnings per share, continuing operations (in dollars per share)	$ (0.08)	$ 0.14
Restatement Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Costs of revenue, excluding depreciation and amortization		$ 300
Other income, net		100
Provision for income taxes		$ (2,400)
Basic earnings per share, continuing operations (in dollars per share)		$ (0.05)
Diluted earnings per share, continuing operations (in dollars per share)		$ (0.05)
Restatement Adjustment [Member] | Reclassification Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Acquisition-related contingent consideration, net of current portion		$ (6,800)
Acquisition-related contingent consideration, current		6,800
Restatement Adjustment [Member] | Contracts Accounted for under Percentage-of-Completion [Member] | Reclassification Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Other current liabilities		(4,200)
Costs and earnings in excess of billings		(4,200)
Restatement Adjustment [Member] | Electrical Transmission [Member] | Contracts Accounted for under Percentage-of-Completion [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue		$ (6,200)