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
		Nov. 30, 2018	Nov. 30, 2017
Earnings Per Share Disclosure [Line Items]
Weighted average basic common shares outstanding	[1]	32,640	29,332
Dilutive effect of restricted stock units	[2]	453	33
Weighted average diluted common shares outstanding		33,093	32,696
2018 Senior Notes
Earnings Per Share Disclosure [Line Items]
Dilutive effect of convertible notes	[3]		3,331

[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 2018 Convertible notes was included for the three months ended November 30, 2017 as they were considered dilutive under the "if converted" method as further discussed below. The 2018 Convertible notes matured on April 1, 2018.