Employee Benefits (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010	Oct. 01, 2011	Sep. 30, 2011
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
Defined Contribution Plan, Period Contributions	$ 3	$ 3	$ 1
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	17	17
Defined Benefit Plan, Benefit Obligation	18	15
Defined Benefit Plan, Funded Status of Plan	(1)	2
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.67%	4.97%
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	16	16
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1	1
Multiemployer Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of Multiemployer Plans	13
Multiemployer Plan, Period Contributions	4	3	3
Steelworkers Western Independent Shops Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plans, Collective-Bargaining Arrangement, Expiration Date	Mar. 31, 2016
Multiemployer Plans, Funding Status, Percentage					77.40%
Multiemployer Plans, Annual Contribution Rate Increase	6.00%
IRC 412(e) Funded Ratio				65.20%
Multiemployer Plan, Period Contributions	2	2	2
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2	2
Defined Benefit Plan, Benefit Obligation	4	3
Defined Benefit Plan, Funded Status of Plan	(4)	(3)
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Estimated Future Benefit Payments	4
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Estimated Future Benefit Payments	$ 1
Minimum [Member] | Steelworkers Western Independent Shops Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Rehabilitation Plan Contributions As A Percent Of Total Contributions	5.00%	5.00%	5.00%