Segments and Related Information (Schedule of Financial Information by Reportable Segment - EBITDA) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
EBITDA:
EBITDA	$ 253.6	$ 247.9	$ 527.4	$ 620.8
Reportable Segments [Member] | Communications [Member]
EBITDA:
EBITDA	79.6	57.1	206.8	154.8
Reportable Segments [Member] | Oil and Gas [Member]
EBITDA:
EBITDA	160.4	212.9	315.0	499.6
Reportable Segments [Member] | Electrical Transmission [Member]
EBITDA:
EBITDA	9.1	7.8	14.2	20.3
Reportable Segments [Member] | Clean Energy and Infrastructure [Member]
EBITDA:
EBITDA	34.4	2.3	69.5	14.4
Reportable Segments [Member] | Other [Member]
EBITDA:
EBITDA	7.6	6.7	22.5	19.4
Corporate [Member]
EBITDA:
EBITDA	$ (37.5)	$ (38.9)	$ (100.6)	$ (87.7)