Note 12 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Millions			6 Months Ended
	Mar. 26, 2018	Jan. 31, 2018	Feb. 28, 2018	Feb. 28, 2017	Mar. 27, 2018	Aug. 31, 2017
Preferred Stock, Shares Authorized			10,000,000			10,000,000
Preferred Stock, Par or Stated Value Per Share			$ 0.01			$ 0.01
Preferred Stock, Shares Issued			0			0
Common Stock, Shares Authorized			150,000,000			150,000,000
Common Stock, Par or Stated Value Per Share			$ 0.01			$ 0.01
Common Stock, Shares, Issued			39,047,153			51,845,132
Treasury Stock, Shares, Retired		13,292,689
Treasury Stock, Retired, Cost Method, Amount		$ 1,700.0
Treasury Stock, Shares			120,000			12,822,100
Treasury Stock, Shares, Acquired			584,920	984,822
Treasury Stock, Value, Acquired, Cost Method			$ 112.9	$ 160.4
Stock Repurchase Program, Remaining Authorized Repurchase Amount				$ 131.2
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period			14,839	101,234
Shares Paid for Tax Withholding for Share Based Compensation			5,563	37,042
Preferred Stock, Shares Outstanding			0			0
Subsequent Event [Member]
Stock Repurchase Program, Remaining Authorized Repurchase Amount					$ 431.2
Stock Repurchase Program, Increase in Authorized Amount	$ 300.0
Common Stock [Member]
Treasury Stock, Retired, Cost Method, Amount		0.1
Additional Paid-in Capital [Member]
Treasury Stock, Retired, Cost Method, Amount		186.7
Retained Earnings [Member]
Treasury Stock, Retired, Cost Method, Amount		$ 1,500.0