Commitments And Contingencies (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended	12 Months Ended
	Nov. 30, 2014	May. 31, 2015	May. 31, 2014	May. 31, 2014	Aug. 31, 2012	Aug. 31, 2014
Commitments And Contingencies [Abstract]
Environmental remediation expense		$ 0	$ 0	$ 0	$ 7,200
Environmental remediation, incremental costs	$ 1,500
Other current liabilities		1,119	1,444	1,444		$ 1,370
Other noncurrent liabilities		6,475	5,025	5,025		5,025
Total environmental remediation liabilities		$ 7,594	$ 6,469	$ 6,469		$ 6,395