Segments and Related Information (Schedule of Financial Information by Reportable Segment- EBITDA and Depreciation) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
EBITDA:
EBITDA	$ 224.1	$ 159.9	$ 422.5	$ 273.8
Depreciation and amortization	107.4	67.5	197.9	128.0
Reportable Segments | Communications
EBITDA:
EBITDA	72.7	76.4	121.5	127.2
Depreciation and amortization	23.8	21.4	45.6	41.0
Reportable Segments | Clean Energy and Infrastructure
EBITDA:
EBITDA	15.6	30.1	26.4	35.0
Depreciation and amortization	10.5	4.7	18.1	8.7
Reportable Segments | Oil and Gas
EBITDA:
EBITDA	138.1	80.1	305.7	154.5
Depreciation and amortization	56.2	32.1	108.3	60.2
Reportable Segments | Electrical Transmission
EBITDA:
EBITDA	9.3	(3.2)	12.9	5.1
Depreciation and amortization	14.1	6.6	20.2	12.4
Reportable Segments | Other
EBITDA:
EBITDA	8.3	7.5	15.8	14.9
Depreciation and amortization	0.0	0.0	0.0	0.0
Corporate
EBITDA:
EBITDA	(19.9)	(31.0)	(59.8)	(62.9)
Depreciation and amortization	$ 2.8	$ 2.7	$ 5.7	$ 5.7