Goodwill and Other Intangible Assets (Schedule of Goodwill by Segment) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill, balance as of September 30, 2015	$ 1,064,822	$ 1,082,466
Communications [Member]
Goodwill [Line Items]
Goodwill, balance as of September 30, 2015	418,500
Oil and Gas [Member]
Goodwill [Line Items]
Goodwill, balance as of September 30, 2015	378,800
Electrical Transmission [Member]
Goodwill [Line Items]
Goodwill, balance as of September 30, 2015	149,900
Power Generation and Industrial [Member]
Goodwill [Line Items]
Goodwill, balance as of September 30, 2015	$ 117,600