Segment Geographic and Market Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net sales by product line
Sales Revenue, Net	$ 233,661	$ 248,044	$ 242,876	$ 217,788	$ 219,387	$ 228,822	$ 218,825	$ 174,003	$ 942,369	$ 841,037	$ 691,864
Metalcasting [Member]
Net sales by product line
Sales Revenue, Net									251,467	204,577	139,849
Oilfield Services [Member]
Net sales by product line
Sales Revenue, Net									193,632	154,621	119,821
Specialty Materials [Member]
Net sales by product line
Sales Revenue, Net									105,788	107,287	98,097
Lining Technologies [Member]
Net sales by product line
Sales Revenue, Net									104,220	110,614	103,046
Building Materials [Member]
Net sales by product line
Sales Revenue, Net									80,686	58,860	55,823
Pet Products [Member]
Net sales by product line
Sales Revenue, Net									55,924	61,971	66,441
Basic Minerals [Member]
Net sales by product line
Sales Revenue, Net									55,088	49,199	27,901
Contracting Minerals [Member]
Net sales by product line
Sales Revenue, Net									35,992	31,075	25,519
Drilling Products [Member]
Net sales by product line
Sales Revenue, Net									31,385	26,285	22,727
Transportation [Member]
Net sales by product line
Sales Revenue, Net									54,113	52,225	46,642
Intersegment Shipping Revenue [Member]
Net sales by product line
Sales Revenue, Net									$ (25,926)	$ (15,677)	$ (14,002)