Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012
Assets
Cash and cash equivalents	$ 17,130	$ 38,284
Short-term investments	40,932	8,813
Accounts receivable – trade, net of allowance for doubtful accounts of $972 in 2013 and $595 in 2012	123,075	119,069
Accounts receivable – other	2,607	7,636
Inventories	96,821	90,183
Deferred income taxes	4,556	9,040
Prepaid expenses and other	3,399	16,657
Total current assets	288,520	289,682
Property, plant and equipment, net	551,234	492,109
Deferred income taxes	44,421	42,427
Intellectual property and other, net	11,146	13,193
Total assets	895,321	837,411
Trade accounts payable	38,269	40,600
Accrued expenses	43,664	43,135
Total current liabilities	81,933	83,735
Long-term debt	41,172	58,578
Accrued postretirement benefits	29,443	30,602
Deferred income taxes	4,399	4,930
Payable related to exchange of alternative fuel mixture credits	49,353	49,741
Other liabilities	6,328	6,789
Stockholders’ equity:
Preferred stock, $.01 par value; 10,000,000 shares authorized; none issued or outstanding	0	0
Common stock, $.01 par value; 100,000,000 shares authorized; 43,142,770 shares issued; 38,903,102 and 38,823,455 shares outstanding at June 30, 2013 and 2012, respectively	431	431
Additional paid-in capital	48,932	47,206
Accumulated other comprehensive income	30,085	24,968
Retained earnings	674,199	599,339
Treasury shares, 3,614,754 and 3,690,682 shares at June 30, 2013 and 2012, respectively	(70,954)	(68,908)
Total stockholders’ equity	682,693	603,036
Total liabilities and stockholders’ equity	$ 895,321	$ 837,411