Fair Value (Narrative) (Details) (USD $)	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of fair value hierarchy	3
Fair value of long-term debt, predominantly publicly held	$ 1,220,000,000	$ 1,240,000,000
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Plant, property and equipment		56,795,000
Fair value, inputs, level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Plant, property and equipment	9,000,000	56,795,000
Fair value measurements recognized loss [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Plant, property and equipment	$ 3,300,000	$ 89,448,000