Segments and Related Information (Schedule of Financial Information by Reportable Segment - Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue:
Revenue (in dollars)	$ 1,775,424	$ 1,416,604
Communications [Member] | Customer Concentration Risk [Member] | Revenue [Member] | Utilities [Member]
Revenue:
Utilities customers, percentage of Communications segment revenue	20.10%	15.20%
Reportable Segments [Member] | Communications [Member]
Revenue:
Revenue (in dollars)	$ 568,600	$ 644,100
Reportable Segments [Member] | Clean Energy and Infrastructure [Member]
Revenue:
Revenue (in dollars)	350,400	286,300
Reportable Segments [Member] | Oil and Gas [Member]
Revenue:
Revenue (in dollars)	725,500	359,100
Reportable Segments [Member] | Electrical Transmission [Member]
Revenue:
Revenue (in dollars)	133,500	128,100
Reportable Segments [Member] | Other [Member]
Revenue:
Revenue (in dollars)	0	0
Eliminations [Member]
Revenue:
Revenue (in dollars)	$ (2,600)	$ (1,000)