Earnings Per Share - Reconciliation of Shares Used in Computation of Basic and Diluted Earnings Per Common Share (Detail) - shares shares in Thousands		12 Months Ended
		Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Earnings Per Share Disclosure [Line Items]
Weighted average basic common shares outstanding	[1]	30,857	29,225	29,156
Dilutive effect of restricted stock units	[2]	157	42	98
Weighted average diluted common shares outstanding		32,835	32,562	32,468
2018 Senior Notes
Earnings Per Share Disclosure [Line Items]
Dilutive effect of convertible notes	[3]	1,821	3,295	3,214

[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. No restricted stock and restricted stock units were anti-dilutive for the years ended August 31, 2018, 2017 and 2016.

[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 as they were considered dilutive under the "if converted" method as further discussed below. The 2018 Convertible notes matured on April 1, 2018.