Commitments And Contingencies (Summary Of Undiscounted Environmental Remediation Liability Classifications) (Details) - USD ($) $ in Thousands	May 31, 2018	Aug. 31, 2017	May 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Other current liabilities	$ 1,281	$ 2,095	$ 2,134
Other noncurrent liabilities	15,513	15,937	16,161
Total environmental remediation liabilities	$ 16,794	$ 18,032	$ 18,295