Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	May 31, 2012	Aug. 31, 2011
Accounts receivable, allowance for doubtful accounts	$ 6,755	$ 6,148
Property, plant and equipment, accumulated depreciation	518,903	471,305
Intangibles, accumulated amortization	$ 17,804	$ 20,846
Preferred stock, shares authorized	20,000	20,000
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares issued	0	0
Common Class A [Member]
Common stock, shares authorized	75,000	75,000
Common stock, par value	$ 1.00	$ 1.00
Common stock, shares issued	25,095	24,241
Common stock, shares outstanding	25,095	24,241
Common Class B [Member]
Common stock, shares authorized	25,000	25,000
Common stock, par value	$ 1.00	$ 1.00
Common stock, shares issued	1,790	3,060
Common stock, shares outstanding	1,790	3,060