Fair Value (Tables)

6 Months Ended

Feb. 28, 2013

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The following tables summarize information regarding the Company's financial assets and financial liabilities that were measured at fair value on a recurring basis:

			Fair Value Measurements at Reporting Date Using
(in thousands)	February 28, 2013		Quoted Prices in Active Markets  for Identical Assets (Level 1)		Significant  Other Observable Inputs (Level 2)		Significant Unobservable  Inputs (Level 3)
Assets:
Money market investments (1)	$	82,885	$	82,885	$	—	$	—
Commodity derivative assets (2)	1,923		1,923		—		—
Foreign exchange derivative assets (2)	1,104		—		1,104
Liabilities:
Commodity derivative liabilities (2)	1,060		1,052		8		—
Foreign exchange derivative liabilities (2)	429		—		429		—
Other derivative liabilities (2)	4		—		4		—

			Fair Value Measurements at Reporting Date Using
(in thousands)	August 31, 2012		Quoted Prices in Active Markets  for Identical Assets (Level 1)		Significant  Other Observable  Inputs (Level 2)		Significant Unobservable  Inputs (Level 3)
Assets:
Money market investments (1)	$	172,462	$	172,462	$	—	$	—
Commodity derivative assets (2)	407		407		—		—
Foreign exchange derivative assets (2)	1,468		—		1,468		—
Liabilities:
Commodity derivative liabilities (2)	995		993		2		—
Foreign exchange derivative liabilities (2)	2,520		—		2,520		—
Other derivative liabilities (2)	32		—		32		—

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(1) Money market investments are short-term in nature, and the value is determined by broker quoted prices in active markets. The investment portfolio mix can change each period based on the Company's assessment of investment options.

(2) Derivative assets and liabilities classified as Level 1 are commodity futures contracts valued based on quoted market prices in the London Metal Exchange or the New York Mercantile Exchange. Amounts in Level 2 are based on broker quotes in the over-the-counter market. Further discussion regarding the Company's use of derivatives and the classification of the assets and liabilities is included in Note 9. Derivatives and Risk Management.

Fair Value, by Balance Sheet Grouping [Table Text Block]

The carrying values and estimated fair values of the Company's financial assets and liabilities that are not required to be measured at fair value are as follows:

		February 28, 2013		August 31, 2012
(in thousands)	Fair Value Hierarchy	Carrying Value	Fair Value	Carrying Value	Fair Value
$200 million notes at 5.625% due November 2013 (1)	Level 2	202,857	208,607	204,873	212,413
$400 million notes at 6.50% due July 2017 (1)	Level 2	413,005	444,341	414,491	434,991
$500 million notes at 7.35% due August 2018 (1)	Level 2	525,241	569,791	527,554	559,894

(1) The fair value of the notes is calculated based on indicated market values.