Segments and Operations by Geographic Area (Schedule of Segment Reporting Information, by Segment) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting Information [Line Items]
Revenue	$ 918,648,000	$ 738,257,000
Depreciation	31,753,000	20,954,000
Amortization	4,200,000	2,800,000
Segment, Continuing Operations [Member]
Segment Reporting Information [Line Items]
Revenue	918,600,000	738,300,000
EBITDA	73,500,000	49,200,000
Depreciation	31,753,000	20,717,000
Amortization	4,200,000	2,800,000
Segment, Continuing Operations [Member] | Property and Equipment [Member]
Segment Reporting Information [Line Items]
Depreciation	27,600,000	17,900,000
Intersegment Elimination [Member] | Segment, Continuing Operations [Member]
Segment Reporting Information [Line Items]
Revenue	(800,000)	(700,000)
EBITDA	0	(100,000)
Amortization	0	0
Intersegment Elimination [Member] | Segment, Continuing Operations [Member] | Property and Equipment [Member]
Segment Reporting Information [Line Items]
Depreciation	0	0
Communications [Member] | Reportable Segment [Member] | Segment, Continuing Operations [Member]
Segment Reporting Information [Line Items]
Revenue	424,900,000	389,100,000
EBITDA	46,400,000	32,800,000
Amortization	1,100,000	400,000
Communications [Member] | Reportable Segment [Member] | Segment, Continuing Operations [Member] | Property and Equipment [Member]
Segment Reporting Information [Line Items]
Depreciation	7,100,000	6,200,000
Oil and Gas [Member] | Reportable Segment [Member] | Segment, Continuing Operations [Member]
Segment Reporting Information [Line Items]
Revenue	318,800,000	167,700,000
EBITDA	42,400,000	12,600,000
Amortization	2,200,000	500,000
Oil and Gas [Member] | Reportable Segment [Member] | Segment, Continuing Operations [Member] | Property and Equipment [Member]
Segment Reporting Information [Line Items]
Depreciation	16,400,000	8,700,000
Electrical Transmission [Member] | Reportable Segment [Member] | Segment, Continuing Operations [Member]
Segment Reporting Information [Line Items]
Revenue	84,600,000	64,400,000
EBITDA	3,400,000	8,400,000
Amortization	300,000	1,200,000
Electrical Transmission [Member] | Reportable Segment [Member] | Segment, Continuing Operations [Member] | Property and Equipment [Member]
Segment Reporting Information [Line Items]
Depreciation	2,000,000	1,400,000
Power Generation and Industrial [Member] | Reportable Segment [Member] | Segment, Continuing Operations [Member]
Segment Reporting Information [Line Items]
Revenue	88,900,000	117,400,000
EBITDA	(200,000)	5,000,000
Amortization	500,000	700,000
Power Generation and Industrial [Member] | Reportable Segment [Member] | Segment, Continuing Operations [Member] | Property and Equipment [Member]
Segment Reporting Information [Line Items]
Depreciation	1,200,000	1,000,000
All Other Segments [Member] | Reportable Segment [Member] | Segment, Continuing Operations [Member]
Segment Reporting Information [Line Items]
Revenue	2,300,000	400,000
EBITDA	100,000	(200,000)
Amortization	0	0
All Other Segments [Member] | Reportable Segment [Member] | Segment, Continuing Operations [Member] | Property and Equipment [Member]
Segment Reporting Information [Line Items]
Depreciation	0	0
Corporate [Member] | Reportable Segment [Member] | Segment, Continuing Operations [Member]
Segment Reporting Information [Line Items]
Revenue	0	0
EBITDA	(18,600,000)	(9,300,000)
Amortization	0	0
Corporate [Member] | Reportable Segment [Member] | Segment, Continuing Operations [Member] | Property and Equipment [Member]
Segment Reporting Information [Line Items]
Depreciation	$ 900,000	$ 700,000