Goodwill and Other Intangible Assets (Rollforward of Goodwill by Segment) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2014	Dec. 31, 2013
Goodwill [Line Items]
Goodwill, beginning balance		$ 902,044	$ 826,600
Additions from new business combinations		184,800	65,300
Currency translation adjustments		(10,800)	(3,500)
Goodwill, ending balance		1,082,466	902,044
Earn-Out Arrangements [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration, net	[1]	6,500	13,600
Communications [Member]
Goodwill [Line Items]
Goodwill, beginning balance		326,800	306,100
Additions from new business combinations		84,400	7,100
Currency translation adjustments		0	0
Goodwill, ending balance		417,700	326,800
Communications [Member] | Earn-Out Arrangements [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration, net	[1]	6,500	13,600
Oil and Gas [Member]
Goodwill [Line Items]
Goodwill, beginning balance		307,700	273,400
Additions from new business combinations		100,400	37,800
Currency translation adjustments		(10,800)	(3,500)
Goodwill, ending balance		397,300	307,700
Oil and Gas [Member] | Earn-Out Arrangements [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration, net	[1]	0	0
Electrical Transmission [Member]
Goodwill [Line Items]
Goodwill, beginning balance		149,900	129,500
Additions from new business combinations		0	20,400
Currency translation adjustments		0	0
Goodwill, ending balance		149,900	149,900
Electrical Transmission [Member] | Earn-Out Arrangements [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration, net	[1]	0	0
Power Generation and Industrial [Member]
Goodwill [Line Items]
Goodwill, beginning balance		117,600	117,600
Additions from new business combinations		0	0
Currency translation adjustments		0	0
Goodwill, ending balance		117,600	117,600
Power Generation and Industrial [Member] | Earn-Out Arrangements [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration, net	[1]	$ 0	$ 0

[1] Represents contingent consideration for acquisitions prior to January 1, 2009, which is accrued as earned, in accordance with U.S. GAAP.