Note 17 - Income Taxes (Details Textual) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended		6 Months Ended	9 Months Ended	12 Months Ended
	Feb. 08, 2018	Feb. 28, 2018	Nov. 30, 2017	Feb. 28, 2018	May 31, 2018	Dec. 31, 2018	Aug. 31, 2018	Aug. 31, 2018	Dec. 31, 2017	Aug. 31, 2017	Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2016	Aug. 31, 2016		Aug. 31, 2015
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount			$ 9,500		$ 9,500
Income Tax Expense (Benefit), Continuing Operations, Transition Tax	$ 23,200	$ 23,200		$ 23,200
Effective Income Tax Rate Reconciliation, Operational Realignment, Basis Point										2.00%
Effective Income Tax Rate Reconciliation, Percent, Total							24.10%	24.10%		25.00%	25.00%	26.50%		26.50%	[1]
Effective Income Tax Rate Reconciliation, Tax Credit, Research, Amount													$ 10,500
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent							25.70%	25.70%	35.00%		35.00%			35.00%
Undistributed Earnings of Foreign Subsidiaries									$ 250,000
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability		$ 2,300		$ 2,300
Unrecognized Tax Benefits, Ending Balance							$ 9,223	$ 9,223		$ 11,484	$ 11,484	$ 8,782	$ 8,782	$ 8,782		$ 6,776
Unrecognized Tax Benefits, Interest on Income Taxes Accrued							$ 1,100	$ 1,100
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent						21.00%

[1] The fiscal 2016 effective tax rate of 26.5% includes income tax benefits of $10.5 million primarily from the permanent reenactment of the U.S. Federal R&D Tax Credit ("R&D tax credit") in December 2015, finalizing the fiscal 2015 tax returns and other discrete items. The reenactment of the R&D tax credit was retroactive to January 1, 2015, and eliminates the yearly uncertainty surrounding the extension of the credit.