CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 16,286	$ 53,372
Trade receivables, net	17,118	15,595
Inventories	10,969	10,764
Prepaid expenses and other current assets	1,170	1,207
Total current assets	45,543	80,938
Property, plant and equipment, at cost	238,360	236,740
Less accumulated depreciation and depletion	(118,662)	(115,422)
Property, plant and equipment, net	119,698	121,318
Other assets, net	284	302
Total assets	165,525	202,558
Current liabilities:
Current installments of debt	6,250	6,250
Accounts payable	4,799	5,392
Accrued expenses	4,596	4,376
Total current liabilities	15,645	16,018
Debt, excluding current installments	25,417	26,667
Deferred tax liabilities, net	13,080	12,497
Other liabilities	3,999	4,363
Total liabilities	58,141	59,545
Stockholders' equity:
Common stock	647	645
Additional paid-in capital	17,532	17,199
Accumulated other comprehensive loss	(2,856)	(3,001)
Retained earnings	141,534	136,910
Less treasury stock, at cost	(49,473)	(8,740)
Total stockholders' equity	107,384	143,013
Total liabilities and stockholders' equity	$ 165,525	$ 202,558