Income Taxes (Summary Of Tax Credit Carryforwards) (Details) $ in Thousands	12 Months Ended
	Aug. 31, 2020 USD ($)
Tax Credit Carryforward [Line Items]
Credits Generated	$ 19,311
Credits Used in Prior Years	(10,161)
Credits Used in Current Year
Credits Carried Forward	$ 9,150
2011 [Member]
Tax Credit Carryforward [Line Items]
Credit Generated in Fiscal Year Ended August 31,	Aug. 31, 2011
Credit Expires August 31,	Aug. 31, 2021
Credits Generated	$ 3,445
Credits Used in Prior Years	(414)
Credits Used in Current Year
Credits Carried Forward	$ 3,031
2012 [Member]
Tax Credit Carryforward [Line Items]
Credit Generated in Fiscal Year Ended August 31,	Aug. 31, 2012
Credit Expires August 31,	Aug. 31, 2022
Credits Generated	$ 2,563
Credits Used in Prior Years	(2,563)
Credits Used in Current Year
Credits Carried Forward
2013 [Member]
Tax Credit Carryforward [Line Items]
Credit Generated in Fiscal Year Ended August 31,	Aug. 31, 2013
Credit Expires August 31,	Aug. 31, 2023
Credits Generated	$ 2,815
Credits Used in Prior Years	(2,815)
Credits Used in Current Year
Credits Carried Forward
2014 [Member]
Tax Credit Carryforward [Line Items]
Credit Generated in Fiscal Year Ended August 31,	Aug. 31, 2014
Credit Expires August 31,	Aug. 31, 2024
Credits Generated	$ 1,378
Credits Used in Prior Years	(1,378)
Credits Used in Current Year
Credits Carried Forward
2015 [Member]
Tax Credit Carryforward [Line Items]
Credit Generated in Fiscal Year Ended August 31,	Aug. 31, 2015
Credit Expires August 31,	Aug. 31, 2025
Credits Generated	$ 1,422
Credits Used in Prior Years	(1,422)
Credits Used in Current Year
Credits Carried Forward
2016 [Member]
Tax Credit Carryforward [Line Items]
Credit Generated in Fiscal Year Ended August 31,	Aug. 31, 2016
Credit Expires August 31,	Aug. 31, 2026
Credits Generated	$ 1,569
Credits Used in Prior Years	(1,569)
Credits Used in Current Year
Credits Carried Forward
2017 [Member]
Tax Credit Carryforward [Line Items]
Credit Generated in Fiscal Year Ended August 31,	Aug. 31, 2017
Credit Expires August 31,	Aug. 31, 2027
Credits Generated	$ 1,804
Credits Used in Prior Years
Credits Used in Current Year
Credits Carried Forward	$ 1,804
2018 [Member]
Tax Credit Carryforward [Line Items]
Credit Generated in Fiscal Year Ended August 31,	Aug. 31, 2018
Credit Expires August 31,	Aug. 31, 2028
Credits Generated	$ 1,727
Credits Used in Prior Years
Credits Used in Current Year
Credits Carried Forward	$ 1,727
2019 [Member]
Tax Credit Carryforward [Line Items]
Credit Generated in Fiscal Year Ended August 31,	Aug. 31, 2019
Credit Expires August 31,	Aug. 31, 2029
Credits Generated	$ 1,578
Credits Used in Prior Years
Credits Used in Current Year
Credits Carried Forward	$ 1,578
2020 [Member]
Tax Credit Carryforward [Line Items]
Credit Generated in Fiscal Year Ended August 31,	Aug. 31, 2020
Credit Expires August 31,	Aug. 31, 2030
Credits Generated	$ 1,010
Credits Used in Prior Years
Credits Used in Current Year
Credits Carried Forward	$ 1,010