Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss (Detail) (USD $)
In Thousands, unless otherwise specified
Aug. 31, 2012
Aug. 31, 2011
Amounts Reclassified Out Of Accumulated Other Comprehensive Income Loss [Abstract]    
Net unrealized loss on derivatives, net of tax $ 1,638 $ 731
Postretirement obligations, net of tax (17,231) (8,290)
Accumulated Other Comprehensive Income (Loss), Net of Tax $ (15,593) $ (7,559)