Fair Value (Narrative) (Details) (USD $)	3 Months Ended				3 Months Ended
	Nov. 30, 2012 levels	Nov. 30, 2012 Fair value, inputs, level 2 [Member] Fair value, measurements, recurring [Member]	Aug. 31, 2012 Fair value, inputs, level 2 [Member] Fair value, measurements, recurring [Member]	Nov. 30, 2012 Fair value, inputs, level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Nov. 30, 2012 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				$ 3,800,000
Impairment charges for plant, property and equipment					3,000,000
Fair value of long-term debt, predominantly publicly held		$ 1,230,000,000	$ 1,220,000,000
Number of fair value hierarchy	3