Note 11 - Common Stock and Earnings Per Share - Shares of Common Stock Outstanding (Details) - shares		6 Months Ended
		Feb. 28, 2018	Feb. 28, 2017
Balance (in shares)		39,023,032	40,038,000
Common stock issued for employee stock plans (in shares)		495,000	506,000
Repurchase of common stock (in shares)		(584,920)	(984,822)
Balance (in shares)		38,927,153	39,419,000
Repurchase of Common Stock from Employees [Member]
Repurchase of common stock (in shares)	[1]	(6,000)	(37,000)
Share Repurchase Program [Member]
Repurchase of common stock (in shares)		(585,000)	(985,000)
ASR Agreement [Member]
Repurchase of common stock (in shares)			(103,000)

[1] For the six months ended February 28, 2018 and 2017, the Company repurchased 5,563 and 37,042 shares, or $1.0 million and $5.7 million, of common stock, respectively, in settlement of employee tax withholding obligations due upon the vesting of restricted stock.