Segments and Related Information (Schedule of Financial Information by Reportable Segment - Assets) (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets:
Assets		$ 2,940,197	$ 3,563,980	$ 2,923,200	[1]
Assets, discontinued operations				12,500
Continuing Operations [Member]
Assets:
Assets		2,940,200	3,564,000	2,910,700	[1]
Oil and Gas [Member]
Assets:
Assets, equity method investees, net amount of investments	[2]	1,700	2,700
Reportable Segments [Member] | Communications [Member]
Assets:
Assets		1,032,200	1,197,400	973,500	[1]
Reportable Segments [Member] | Oil and Gas [Member]
Assets:
Assets	[2]	1,131,400	1,389,500	1,060,800	[1]
Reportable Segments [Member] | Electrical Transmission [Member]
Assets:
Assets		409,100	489,500	449,300	[1]
Reportable Segments [Member] | Power Generation and Industrial [Member]
Assets:
Assets		252,500	340,100	324,500	[1]
Reportable Segments [Member] | Other [Member]
Assets:
Assets		34,300	24,600	22,800	[1]
Corporate [Member]
Assets:
Assets		$ 80,700	$ 122,900	$ 79,800	[1]

[1] Consolidated total assets were $2,923.2 million as of December 31, 2013, including assets of discontinued operations of $12.5 million.

[2] ncludes $1.7 million and $2.7 million, net, of investments in equity method investees as of December 31, 2015 and 2014, respectively.