Inventories (Schedule Of Inventories) (Details) (USD $) In Thousands, unless otherwise specified	May 31, 2012	Aug. 31, 2011	May 31, 2011
Inventories [Abstract]
FIFO inventory	$ 29,296	$ 22,614	$ 25,720
LIFO reserves	(6,996)	(7,178)	(6,874)
LIFO inventory	22,300	15,436	18,846
Weighted average inventory	21,465	20,848	21,743
Other FIFO inventory	20,359	15,407	14,434
Obsolescence reserve	(2,005)	(2,167)	(2,190)
Total inventories	$ 62,119	$ 49,524	$ 52,833