Segments and Related Information (Schedule of Segment Reporting Information by Segment - Revenue) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Revenue	$ 1,104,556	$ 977,624	$ 2,068,585	$ 1,896,272
Reportable Segments [Member] | Communications [Member]
Segment Reporting Information [Line Items]
Revenue	528,100	496,600	975,200	921,600
Reportable Segments [Member] | Oil and Gas [Member]
Segment Reporting Information [Line Items]
Revenue	365,700	296,900	745,500	615,700
Reportable Segments [Member] | Electrical Transmission [Member]
Segment Reporting Information [Line Items]
Revenue	114,500	118,600	194,600	203,100
Reportable Segments [Member] | Power Generation and Industrial [Member]
Segment Reporting Information [Line Items]
Revenue	94,500	63,300	148,800	152,200
Reportable Segments [Member] | Other [Member]
Segment Reporting Information [Line Items]
Revenue	2,700	3,400	5,400	5,700
Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	$ (900)	$ (1,200)	$ (900)	$ (2,000)