Segments and Related Information (Schedule of Financial Information by Reportable Segment - EBITDA) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
EBITDA:
EBITDA	$ 198.4	$ 114.0
Reportable Segments [Member] | Communications [Member]
EBITDA:
EBITDA	48.9	50.8
Reportable Segments [Member] | Clean Energy and Infrastructure [Member]
EBITDA:
EBITDA	10.9	5.0
Reportable Segments [Member] | Oil and Gas [Member]
EBITDA:
EBITDA	167.6	74.4
Reportable Segments [Member] | Electrical Transmission [Member]
EBITDA:
EBITDA	3.6	8.3
Reportable Segments [Member] | Other [Member]
EBITDA:
EBITDA	7.4	7.4
Corporate [Member]
EBITDA:
EBITDA	$ (40.0)	$ (31.9)