Capital Stock (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2018	May 31, 2017
Earnings Per Share [Abstract]
Net earnings	$ 29,012	$ 22,511	$ 16,017	$ 32,551
Weighted average common shares outstanding - basic	60,683	59,675	60,291	59,339
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	381	727	559	716
Diluted	61,064	60,402	60,850	60,055
Basic	$ 0.48	$ 0.38	$ 0.27	$ 0.55
Diluted	$ 0.48	$ 0.37	$ 0.26	$ 0.54
Anti-dilutive securities from stock based compensation plans (excluded from earnings per share calculation)	1,788	1,969	2,338	1,981