Goodwill by Segment Rollforward (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Goodwill [Line Items]
Goodwill, beginning balance	$ 714,760,000		$ 525,600,000
Additions from new business combinations, goodwill	80,200,000		177,400,000
Accruals of acquisition-related contingent consideration	25,500,000	[1]	11,800,000	[1]
Currency translation, goodwill	(200,000)
Goodwill, ending balance	820,341,000		714,760,000
Reportable Segment [Member] | Communications [Member]
Goodwill [Line Items]
Goodwill, beginning balance	258,000,000		227,900,000
Additions from new business combinations, goodwill	36,500,000		28,600,000
Currency translation, goodwill	0
Goodwill, ending balance	302,200,000		258,000,000
Reportable Segment [Member] | Electrical Transmission [Member]
Goodwill [Line Items]
Goodwill, beginning balance	129,500,000		8,800,000
Additions from new business combinations, goodwill	0		120,700,000
Currency translation, goodwill	0
Goodwill, ending balance	129,500,000		129,500,000
Reportable Segment [Member] | Oil and Gas [Member]
Goodwill [Line Items]
Goodwill, beginning balance	209,800,000		171,400,000
Additions from new business combinations, goodwill	43,700,000		28,100,000
Currency translation, goodwill	(200,000)
Goodwill, ending balance	271,100,000		209,800,000
Reportable Segment [Member] | Power Generation and Industrial [Member]
Goodwill [Line Items]
Goodwill, beginning balance	117,500,000		117,500,000
Additions from new business combinations, goodwill	0		0
Currency translation, goodwill	0
Goodwill, ending balance	117,500,000		117,500,000
Earn-out Arrangements [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration	25,500,000	[1]	11,800,000	[1]
Earn-out Arrangements [Member] | Reportable Segment [Member] | Communications [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration	7,700,000	[1]	1,500,000	[1]
Earn-out Arrangements [Member] | Reportable Segment [Member] | Electrical Transmission [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration	0	[1]	0	[1]
Earn-out Arrangements [Member] | Reportable Segment [Member] | Oil and Gas [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration	17,800,000	[1]	10,300,000	[1]
Earn-out Arrangements [Member] | Reportable Segment [Member] | Power Generation and Industrial [Member]
Goodwill [Line Items]
Accruals of acquisition-related contingent consideration	$ 0	[1]	$ 0	[1]

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