Segments and Related Information (Schedule of Financial Information by Reportable Segment - EBITDA) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
EBITDA:
EBITDA	$ 188.7	$ 198.9	$ 293.2	$ 322.4
Reportable Segments [Member] | Communications [Member]
EBITDA:
EBITDA	73.7	59.5	155.8	107.8
Reportable Segments [Member] | Oil and Gas [Member]
EBITDA:
EBITDA	122.7	154.0	155.7	247.9
Reportable Segments [Member] | Electrical Transmission [Member]
EBITDA:
EBITDA	(2.7)	3.5	1.9	6.7
Reportable Segments [Member] | Power Generation and Industrial [Member]
EBITDA:
EBITDA	9.8	4.7	14.6	5.6
Reportable Segments [Member] | Other [Member]
EBITDA:
EBITDA	6.8	6.8	12.7	1.5
Corporate [Member]
EBITDA:
EBITDA	$ (21.6)	$ (29.6)	$ (47.5)	$ (47.1)