Note 12 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended						9 Months Ended
	Jun. 24, 2019	Jan. 31, 2018	May 31, 2019	Feb. 28, 2019	[1]	Nov. 30, 2018	[2]	May 31, 2018	May 31, 2019	May 31, 2018	Aug. 31, 2018
Preferred Stock, Shares Authorized			10,000,000						10,000,000		10,000,000
Preferred Stock, Par or Stated Value Per Share			$ 0.01						$ 0.01		$ 0.01
Preferred Stock, Shares Outstanding, Ending Balance			0						0		0
Common Stock, Shares Authorized			150,000,000						150,000,000		150,000,000
Common Stock, Par or Stated Value Per Share			$ 0.01						$ 0.01		$ 0.01
Common Stock, Shares, Issued, Total			39,982,823						39,982,823		39,264,849
Treasury Stock, Shares, Retired		13,292,689
Treasury Stock, Retired, Cost Method, Amount
Treasury Stock, Shares, Ending Balance			1,765,060						1,765,060		1,072,263
Treasury Stock, Shares, Acquired			175,000					620,000	664,945	1,204,920
Treasury Stock, Value, Acquired, Cost Method			$ 47,555					$ 121,963	$ 152,139	$ 234,836
Stock Repurchase Program, Remaining Authorized Repurchase Amount			$ 89,600						$ 89,600
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation									27,852	5,563
Payment, Tax Withholding, Share-based Payment Arrangement									$ 6,200	$ 1,000
Preferred Stock, Shares Issued, Total			0						0		0
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period				23,000		52,000			75,530	15,063
Subsequent Event [Member]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 299,600
Stock Repurchase Program, Increase in Authorized Amount	$ 210,000
Treasury Stock [Member]
Treasury Stock, Shares, Retired										13,292,689
Treasury Stock, Retired, Cost Method, Amount		$ (1,700,000)								$ (1,697,205)
Treasury Stock, Shares, Acquired			175,000					620,000	664,945	1,204,920
Treasury Stock, Value, Acquired, Cost Method			$ 47,555					$ 121,963	$ 152,139	$ 234,836
Common Stock [Member]
Treasury Stock, Shares, Retired										13,292,689
Treasury Stock, Retired, Cost Method, Amount		100								$ 133
Treasury Stock, Shares, Acquired
Treasury Stock, Value, Acquired, Cost Method
Additional Paid-in Capital [Member]
Treasury Stock, Retired, Cost Method, Amount		186,700								186,717
Treasury Stock, Value, Acquired, Cost Method
Retained Earnings [Member]
Treasury Stock, Retired, Cost Method, Amount		$ 1,500,000								1,510,355
Treasury Stock, Value, Acquired, Cost Method

[1] The majority of the vested restricted stock awards related to the final vesting of awards granted on February 9, 2015, which vested 100% on the four year anniversary date of the grant.

[2] The majority of the vested restricted stock awards related to the final vesting of awards granted on November 1, 2013, which cliff vested 60% after three years on November 1, 2016 and 40% after five years on November 1, 2018.