STOCKHOLDERS’ EQUITY AND EARNINGS PER SHARE ATTRIBUTABLE TO CMC (Narrative) (Details) - USD ($)	6 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Nov. 30, 2014
Earnings Per Share [Abstract]
Stock repurchase program, authorized amount			$ 100,000,000.0
Stock repurchase program, shares purchased (shares)	0	0
Stock repurchase program, remaining authorized repurchase amount	$ 27,600,000