Summary of Significant Accounting Policies New Accounting Pronouncements (Details) - USD ($) $ in Thousands	Aug. 31, 2021	Aug. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	$ 51,589	$ 48,733
Retained Earnings (Accumulated Deficit) [Abstract]
Retained earnings	$ 953,339	917,671
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset		60,800
Accounting Standards Update 2016-02 [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Retained Earnings (Accumulated Deficit) [Abstract]
Retained earnings		$ 200