STOCKHOLDERS’ EQUITY AND EARNINGS PER SHARE ATTRIBUTABLE TO CMC (Narrative) (Details) - USD ($)	3 Months Ended
	Nov. 30, 2015	Nov. 30, 2014
Earnings Per Share [Abstract]
Stock repurchase program, authorized amount		$ 100,000,000.0
Stock repurchase program, shares purchased (shares)	316,086	560,493
Stock repurchase program, average purchase price per share (in USD per share)	$ 14.41	$ 16.67
Stock repurchase program, remaining authorized repurchase amount	$ 53,600,000