Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2011

Summary Of Significant Accounting Policies [Abstract]

Revenue by segment

	Percentage of Net Sales
	2011		2010		2009
Minerals and materials		51%		51%		49%
Environmental		26%		26%		29%
Oilfield services		21%		18%		17%
Transportation		6%		6%		7%
Intersegment sales		-4%		-1%		-2%
		100%		100%		100%

Reconciliation between basic and diluted earnings per share

	2011		2010		2009
Weighted average common shares outstanding for the year		31,708,949		31,178,813		30,764,282
Dilutive impact of stock equivalents		436,824		368,778		269,432
Weighted average common and common equivalent shares for the year		32,145,773		31,547,591		31,033,714
Common shares outstanding at December 31		31,728,969		31,032,791		30,773,908
Weighted average anti-dilutive shares excluded from the computation of diluted earnings per share		189,768		470,097		938,546