STOCKHOLDERS’ EQUITY AND EARNINGS PER SHARE ATTRIBUTABLE TO CMC (Calculations of the Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Earnings Per Share [Abstract]
Earnings from continuing operations attributable to CMC	$ 10,849	$ 13,465	$ 36,482	$ 47,730
Basic earnings per share:
Shares outstanding for basic earnings per share (shares)	115,429,550	116,688,162	115,725,896	117,244,406
Basic earnings per share attributable to CMC: (in USD per share)	$ 0.09	$ 0.12	$ 0.32	$ 0.41
Diluted earnings per share:
Shares outstanding for basic earnings per share (shares)	115,429,550	116,688,162	115,725,896	117,244,406
Effect of dilutive securities:
Stock-based incentive/purchase plans (shares)	1,078,041	995,314	1,276,926	1,151,438
Shares outstanding for diluted earnings per share (shares)	116,507,591	117,683,476	117,002,822	118,395,844
Diluted earnings per share attributable to CMC: (in USD per share)	$ 0.09	$ 0.11	$ 0.31	$ 0.40
Anti-dilutive shares not included above (shares)	714,342	854,703	714,342	623,042

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Amount of income (loss) from continuing operations attributable to the parent. Also defined as revenue less expenses and taxes from ongoing operations before extraordinary items but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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