Earnings Per Share - Reconciliation of Shares Used in Computation of Basic and Diluted Earnings Per Common Share (Detail) - shares shares in Thousands		3 Months Ended		9 Months Ended
		May 31, 2020	May 31, 2019	May 31, 2020	May 31, 2019
Earnings Per Share Disclosure [Line Items]
Weighted average basic common shares outstanding	[1]	32,690	32,603	32,660	32,623
Dilutive effect of restricted stock units	[2]	788	580	754	538
Weighted average diluted common shares outstanding		33,478	33,183	33,414	33,161
2.875% Convertible Senior Notes
Earnings Per Share Disclosure [Line Items]
Dilutive effect of convertible notes	[3]	0	0	0	0
2.25% Convertible Senior Notes
Earnings Per Share Disclosure [Line Items]
Dilutive effect of convertible notes	[4]	0		0

[1] Restricted stock grants and restricted stock units that are considered participating securities, including some grants subject to certain performance criteria, are included in weighted average basic common shares outstanding when the Company is in a net earnings position.

[2] Restricted stock units that are not considered participating securities and restricted stock units subject to performance criteria, for which actual levels of performance above target have been achieved, are included in weighted average diluted common shares outstanding when the Company is in a net earnings position.

[3] The dilutive effect of the 2.875% Convertible notes was excluded for the three and nine months ended May 31, 2020 and 2019 as the average stock price was less than the applicable conversion price and therefore was considered anti-dilutive.

[4] The 2.25% Convertible notes were issued in July 2019. The dilutive effect of the 2.25% Convertible notes was excluded for the three and nine months ended May 31, 2020 as the average stock price was less than the applicable conversion price and therefore was considered anti-dilutive.