Segments and Related Information (Schedule of Financial Information by Reportable Segment - EBITDA) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
EBITDA:
EBITDA	$ 175.3	$ 151.0	$ 497.7	$ 292.6
Reportable Segments [Member] | Communications [Member]
EBITDA:
EBITDA	65.3	62.8	173.2	190.9
Reportable Segments [Member] | Oil and Gas [Member]
EBITDA:
EBITDA	108.1	117.8	356.1	187.6
Reportable Segments [Member] | Electrical Transmission [Member]
EBITDA:
EBITDA	4.5	(8.3)	11.2	(42.0)
Reportable Segments [Member] | Power Generation and Industrial [Member]
EBITDA:
EBITDA	9.3	6.1	14.8	13.8
Reportable Segments [Member] | Other [Member]
EBITDA:
EBITDA	10.1	(3.1)	11.6	(2.6)
Corporate [Member]
EBITDA:
EBITDA	$ (22.0)	$ (24.3)	$ (69.2)	$ (55.1)