Acquisitions and Divestitures (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Acquisitions:
Net cash paid			$ 4.9	$ 42.5
Construction Products Group
Acquisitions:
Total cost	5.5	32.8	7.5	56.4
Net cash paid	4.9	27.2	4.9	42.5
Goodwill recorded	3.2	22.3	4.0	29.3
Divestitures:
Proceeds	0	0	2.1	8.3
Gain recognized	0	0	1.5	0.7
Goodwill charged off	$ 0	$ 0	$ 0.1	$ 1.0