Long-Term Debt and Commitments (Details)	12 Months Ended					12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)	Dec. 31, 2011 Series 2006A Senior Notes Due 2013 [Member] USD ($)	Dec. 31, 2010 Series 2006A Senior Notes Due 2013 [Member] USD ($)	Dec. 31, 2011 Floating Rate Series 2006A Senior Notes Due 2013 [Member] USD ($)	Dec. 31, 2010 Floating Rate Series 2006A Senior Notes Due 2013 [Member] USD ($)	Dec. 31, 2011 Variable/Fixed Rate Industrial Development Revenue Bonds Due 2012 [Member] USD ($)	Dec. 31, 2010 Variable/Fixed Rate Industrial Development Revenue Bonds Due 2012 [Member] USD ($)	Dec. 31, 2011 Variable/Fixed Rate Industrial Development Revenue Bonds Series 1999 Due 2014 [Member] USD ($)	Dec. 31, 2010 Variable/Fixed Rate Industrial Development Revenue Bonds Series 1999 Due 2014 [Member] USD ($)	Dec. 31, 2011 Installment Obligations [Member] USD ($)	Dec. 31, 2010 Installment Obligations [Member] USD ($)	Dec. 31, 2011 Other Borrowings [Member] USD ($)	Apr. 03, 2011 Other Borrowings [Member] USD ($)	Apr. 03, 2011 Other Borrowings [Member] CNY
Debt Instrument [Line Items]
Long-term debt, gross				$ 50,000,000	$ 50,000,000	$ 25,000,000	$ 25,000,000	$ 8,000,000	$ 8,000,000	$ 8,200,000	$ 8,200,000	$ 1,421,000	$ 1,421,000	$ 1,380,000	$ 1,600,000	10,600,000
Less: Current maturities	8,552,000	0
Long-term debt	85,449,000	92,621,000
Interest rate on debt instrument (in hundredths)				5.53%										6.50%
Maturity date				Oct. 05, 2013		Oct. 05, 2013		Aug. 01, 2012		Nov. 01, 2014
Average interest rates (in hundredths)						0.77%	0.79%	0.31%	0.45%	0.31%	0.45%	4.25%
Term of debt instrument (in years)								15		15				3
Cost of land and limestone ore reserves acquired												17,500,000
Cash paid on closing of land and limestone ore reserves acquisition												6,100,000
Principal amount of debt at issuance												11,400,000
Long-term debt maturities [Abstract]
2012	8,600,000
2013	77,200,000
2014	8,200,000
2015	0
2016	0
Thereafter	0
Short-term Borrowings [Abstract]
Uncommitted short-term bank credit lines, maximum borrowing capacity	185,600,000
Uncommitted short-term bank credit lines, amount outstanding	5,800,000
Short-term debt	5,846,000	4,611,000
Weighted average interest rate on short-term borrowings (in hundredths)	5.30%	3.27%
Interest costs [Abstract]
Interest costs	3,500,000	3,500,000	3,700,000
Capitalized interest cost	$ 300,000	$ 200,000	$ 200,000