Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Share data	3 Months Ended		9 Months Ended
	May 31, 2011	May 31, 2010	May 31, 2011	May 31, 2010
Consolidated Statements of Operations [Abstract]
Net sales	$ 2,076,564	$ 1,765,154	$ 5,650,810	$ 4,489,855
Costs and expenses:
Cost of goods sold	1,861,125	1,645,250	5,205,197	4,253,574
Selling, general and administrative expenses	145,597	108,509	390,772	389,182
Interest expense	18,254	18,184	54,857	57,871
Total cost and expense	2,024,976	1,771,943	5,650,826	4,700,627
Earnings (loss) from continuing operations before income taxes	51,588	(6,789)	(16)	(210,772)
Income taxes (benefit)	14,493	3,952	8,688	(36,101)
Earnings (loss) from continuing operations	37,095	(10,741)	(8,704)	(174,671)
Earnings (loss) from discontinued operations before taxes	(1,429)	4,001	(782)	(62,513)
Income taxes (benefit)	(554)	1,723	(303)	(24,117)
Earnings (loss) from discontinued operations	(875)	2,278	(479)	(38,396)
Net earnings (loss)	36,220	(8,463)	(9,183)	(213,067)
Less net earnings attributable to noncontrolling interests	55	363	163	278
Net earnings loss attributable to CMC	$ 36,165	$ (8,826)	$ (9,346)	$ (213,345)
Basic earnings (loss) per share attributable to CMC:
Earnings (loss) from continuing operations	$ 0.32	$ (0.1)	$ (0.08)	$ (1.54)
Earnings (loss) from discontinued operations	$ (0.01)	$ 0.02		$ (0.34)
Net earnings (loss)	$ 0.31	$ (0.08)	$ (0.08)	$ (1.88)
Diluted earnings (loss) per share attributable to CMC:
Earnings (loss) from continuing operations	$ 0.32	$ (0.1)	$ (0.08)	$ (1.54)
Earnings (loss) from discontinued operations	$ (0.01)	$ 0.02		$ (0.34)
Net earnings (loss)	$ 0.31	$ (0.08)	$ (0.08)	$ (1.88)
Cash dividends per share	$ 0.12	$ 0.12	$ 0.36	$ 0.36
Average basic shares outstanding	115,403,374	114,067,149	114,819,792	113,279,301
Average diluted shares outstanding	116,360,755	114,067,149	114,819,792	113,279,301