Goodwill and Other Intangible Assets (Schedule of Goodwill by Segment) (Details) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill, balance as of March 31, 2015	$ 1,070,294	$ 1,082,466
Communications [Member]
Goodwill [Line Items]
Goodwill, balance as of March 31, 2015	417,700
Oil and Gas [Member]
Goodwill [Line Items]
Goodwill, balance as of March 31, 2015	385,100
Electrical Transmission [Member]
Goodwill [Line Items]
Goodwill, balance as of March 31, 2015	149,900
Power Generation and Industrial [Member]
Goodwill [Line Items]
Goodwill, balance as of March 31, 2015	$ 117,600