Goodwill and Other Intangible Assets (Rollforward of Goodwill by Segment) (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill, beginning balance			$ 1,082,466	$ 902,000
Additions from new business combinations				184,800
Currency translation adjustments			(22,700)	(10,800)
Measurement period adjustments	[1]		(3,600)
Goodwill impairment		$ 68,500	68,500
Goodwill, ending balance		988,511	988,511	1,082,466
Goodwill, accumulated impairment loss		(68,500)	(68,500)
Earn-Out Arrangements [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration, net	[2]		800	6,500
Communications [Member]
Goodwill [Line Items]
Goodwill, beginning balance			417,700	326,800
Additions from new business combinations				84,400
Currency translation adjustments			0	0
Measurement period adjustments	[1]		(3,600)
Goodwill impairment			0
Goodwill, ending balance		414,900	414,900	417,700
Goodwill, accumulated impairment loss		0	0
Communications [Member] | Earn-Out Arrangements [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration, net	[2]		800	6,500
Oil and Gas [Member]
Goodwill [Line Items]
Goodwill, beginning balance			397,300	307,700
Additions from new business combinations				100,400
Currency translation adjustments			(22,700)	(10,800)
Measurement period adjustments	[1]		0
Goodwill impairment		68,500	68,500
Goodwill, ending balance		306,100	306,100	397,300
Goodwill, accumulated impairment loss		(68,500)	(68,500)
Oil and Gas [Member] | Earn-Out Arrangements [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration, net	[2]		0	0
Electrical Transmission [Member]
Goodwill [Line Items]
Goodwill, beginning balance			149,900	149,900
Additions from new business combinations				0
Currency translation adjustments			0	0
Measurement period adjustments	[1]		0
Goodwill impairment			0
Goodwill, ending balance		149,900	149,900	149,900
Goodwill, accumulated impairment loss		0	0
Electrical Transmission [Member] | Earn-Out Arrangements [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration, net	[2]		0	0
Power Generation and Industrial [Member]
Goodwill [Line Items]
Goodwill, beginning balance			117,600	117,600
Additions from new business combinations				0
Currency translation adjustments			0	0
Measurement period adjustments	[1]		0
Goodwill impairment			0
Goodwill, ending balance		117,600	117,600	117,600
Goodwill, accumulated impairment loss		$ 0	0
Power Generation and Industrial [Member] | Earn-Out Arrangements [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration, net	[2]		$ 0	$ 0

[1] Represent adjustments to preliminary estimates of the fair values of net assets acquired within the measurement period. See Note 3 - Acquisitions for discussion of ASU 2015-16, which was adopted in the fourth quarter of 2015.

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