BUSINESS SEGMENT INFORMATION (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended					9 Months Ended		12 Months Ended
	Sep. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment disclosure
Net sales	$ 253.3	$ 235.6	$ 248.1	$ 243.1	$ 218.6	$ 746.3	$ 709.8	$ 943.8	$ 826.2	$ 688.2
Operating profit (loss)	27.6	21.3	26.6	21.0	19.3	79.9	66.9	87.1	69.2	50.0
Assets	912.8					912.8		850.6	807.8
Depreciation, depletion, and amortization	11.5		11.3			33.3	31.2
Capital expenditures	22.0		19.0			54.2	43.8
Research and development (income) expense	2.6		2.4			7.7	6.6
Minerals and materials [Member]
Segment disclosure
Net sales	121.0		122.3			377.3	356.4
Operating profit (loss)	18.0		19.6			62.0	49.1
Assets	450.3					450.3		431.1
Depreciation, depletion, and amortization	5.0		5.5			14.5	15.5
Capital expenditures	9.9		8.7			20.7	17.8
Research and development (income) expense	1.8		1.6			5.4	4.7
Environmental [Member]
Segment disclosure
Net sales	60.4		71.1			172.8	197.6
Operating profit (loss)	6.6		7.8			13.6	17.9
Assets	173.8					173.8		160.0
Depreciation, depletion, and amortization	1.3		1.5			4.0	4.1
Capital expenditures	1.6		4.6			7.9	6.4
Research and development (income) expense	0.6		0.5			1.8	1.6
Oilfield services [Member]
Segment disclosure
Net sales	69.1		50.2			185.5	140.9
Operating profit (loss)	7.9		5.7			20.4	15.2
Assets	211.5					211.5		194.7
Depreciation, depletion, and amortization	4.4		3.4			12.6	9.5
Capital expenditures	7.8		4.9			20.8	17.8
Research and development (income) expense	0.2		0			0.6	0.2
Transportation [Member]
Segment disclosure
Net sales	10.7		14.8			33.5	42.3
Operating profit (loss)	0.2		0.7			0.7	1.9
Assets	3.1					3.1		3.9
Depreciation, depletion, and amortization	0.1		0.1			0.1	0.1
Capital expenditures	0		0			0	0.2
Intersegment sales [Member]
Segment disclosure
Net sales	(7.9)		(10.3)			(22.8)	(27.4)
Corporate [Member]
Segment disclosure
Operating profit (loss)	(5.1)		(7.2)			(16.8)	(17.2)
Assets	74.1					74.1		60.9
Depreciation, depletion, and amortization	0.7		0.8			2.1	2.0
Capital expenditures	2.7		0.8			4.8	1.6
Research and development (income) expense	$ 0		$ 0.3			$ (0.1)	$ 0.1