Segments and Related Information (Schedule of Segment Reporting Information, by Segment - Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Assets	$ 2,919,638	$ 2,416,308	$ 2,094,700
Continuing Operations [Member]
Segment Reporting Information [Line Items]
Assets	2,907,200	2,390,100	1,942,400
Continuing Operations [Member] | Operating Segments [Member] | Communications [Member]
Segment Reporting Information [Line Items]
Assets	973,600	843,500	827,500
Continuing Operations [Member] | Operating Segments [Member] | Oil and Gas [Member]
Segment Reporting Information [Line Items]
Assets	1,058,400	809,200	497,700
Continuing Operations [Member] | Operating Segments [Member] | Electrical Transmission [Member]
Segment Reporting Information [Line Items]
Assets	448,100	311,200	254,800
Continuing Operations [Member] | Operating Segments [Member] | Power Generation and Industrial [Member]
Segment Reporting Information [Line Items]
Assets	324,500	323,800	269,400
Continuing Operations [Member] | Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Assets	22,800	6,900	3,900
Continuing Operations [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Assets	$ 79,800	$ 95,500	$ 89,100