Acquisitions and Divestitures (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended			1 Months Ended			12 Months Ended
	Dec. 31, 2012 acquisition	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010 acquisition	Feb. 28, 2010 Quixote Corporation	Feb. 28, 2010 Quixote Corporation Minimum	Feb. 28, 2010 Quixote Corporation Maximum	Dec. 31, 2012 Construction Products Group acquisition divestiture	Dec. 31, 2011 Construction Products Group acquisition divestiture	Dec. 31, 2010 Construction Products Group divestiture acquisition	Dec. 31, 2010 Energy Equipment Group acquisition	Dec. 31, 2012 Energy Equipment Group	Dec. 31, 2011 Energy Equipment Group
Business Acquisition [Line Items]
Number of acquisitions	1			3				3	4	2	1
Number of divestitures								1	1	2
Total cost					$ 58.1
Debt assumed					40.0
Goodwill	240.4	240.4	219.5		22.7			105.2	84.3			10.9	10.9
Intangible assets					24.2
Estimated economic life of acquired intangible assets						4 years	20 years
Transaction-related expenses					4.6
Write-down of pre-aquisition investment to fair value					1.5
Reclassification from AOCL of previously recognized impairment on investment in Quixote					1.8
Acquisitions:
Total cost		48.8	56.4	70.5
Net cash paid		46.2	42.5	49.9
Goodwill recorded		20.9	29.3	33.3
Divestitures:
Proceeds		2.1	8.3	30.8
Gain recognized		1.5	0.7	3.8
Goodwill charged off		$ 0.1	$ 1.0	$ 16.5