Note 15 - Employee Stock Option and Retirement Plans - Summary of Share-based Awards Available for Grant (Details) - shares			12 Months Ended
		Dec. 19, 2017	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
LTIP [Member]
Balance (in shares)			897,000	1,491,000	2,441,000
Share-based awards canceled/forfeited (in shares)	[1]		252,000	566,000	466,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized		5,750,000	5,750,000
Balance (in shares)			6,298,000	897,000	1,491,000
LTIP [Member] | Non Performance Based [Member]
Granted (in shares)			(575,000)	(713,000)	(622,000)
LTIP [Member] | Performance Shares [Member]
Granted (in shares)			(17,000)	(291,000)	(551,000)
LTIP [Member] | Non-Employee Director Grant [Member]
Granted (in shares)
LTIP [Member] | Restricted Stock [Member]
Granted (in shares)	[2]		(9,000)	(156,000)	(243,000)
Director Plan [Member]
Balance (in shares)			42,000	66,000	88,000
Share-based awards canceled/forfeited (in shares)	[1]		9,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized			250,000
Balance (in shares)			282,398	42,000	66,000
Director Plan [Member] | Non Performance Based [Member]
Granted (in shares)
Director Plan [Member] | Performance Shares [Member]
Granted (in shares)
Director Plan [Member] | Non-Employee Director Grant [Member]
Granted (in shares)			(19,000)	(24,000)	(22,000)
Director Plan [Member] | Restricted Stock [Member]
Granted (in shares)	[2]

[1] Under the Company's Option Plan, for each restricted stock award canceled/forfeited, an equivalent of 2.5 shares is added back to the available share-based awards balance.

[2] Each restricted stock award granted is equivalent to 2.5 shares granted under the Company's Option Plan.