Segments and Related Information (Schedule of Financial Information by Reportable Segment - EBITDA - Continuing Operations) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
EBITDA - Continuing Operations:
EBITDA - Continuing operations		$ 150,000	$ 403,700	$ 427,600
Goodwill and intangible asset impairment		78,625	0	0
Oil and Gas [Member]
EBITDA - Continuing Operations:
Equity in losses from unconsolidated affiliates		3,600	300
Other [Member]
EBITDA - Continuing Operations:
Equity in losses from unconsolidated affiliates		4,400
Corporate [Member]
EBITDA - Continuing Operations:
Goodwill and intangible asset impairment		78,600
Reportable Segments [Member] | Communications [Member]
EBITDA - Continuing Operations:
EBITDA - Continuing operations		194,800	204,000	247,700
Reportable Segments [Member] | Oil and Gas [Member]
EBITDA - Continuing Operations:
EBITDA - Continuing operations	[1]	157,000	195,100	215,900
Reportable Segments [Member] | Electrical Transmission [Member]
EBITDA - Continuing Operations:
EBITDA - Continuing operations		(71,300)	45,000	41,200
Reportable Segments [Member] | Power Generation and Industrial [Member]
EBITDA - Continuing Operations:
EBITDA - Continuing operations		8,800	14,200	(16,300)
Reportable Segments [Member] | Other [Member]
EBITDA - Continuing Operations:
EBITDA - Continuing operations	[2]	(18,800)	(1,200)	500
Corporate [Member]
EBITDA - Continuing Operations:
EBITDA - Continuing operations	[3]	(120,500)	$ (53,400)	$ (61,400)
Goodwill and intangible asset impairment		$ 78,600

[1] Oil and Gas EBITDA includes equity in losses from unconsolidated affiliates of $3.6 million and $0.3 million for the years ended December 31, 2015 and 2014, respectively.

[2] Other EBITDA includes equity in losses from unconsolidated affiliates of $4.4 million for the year ended December 31, 2015.

[3] Corporate EBITDA includes goodwill and intangible asset impairment of $78.6 million for the year ended December 31, 2015.