Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2015	Feb. 28, 2014	Aug. 31, 2014
Corporate Joint Venture
Related Party Transaction [Line Items]
Purchases from joint ventures	$ 6	$ 7	$ 13	$ 14
Accounts Receivable, Related Parties	0		0		1
Auto Parts Business Segment President | Partnership Interest
Related Party Transaction [Line Items]
Related Party Noncontrolling Ownership Percentage By Noncontrolling Owners	25.00%		25.00%
Related Party Noncontrolling Ownership Percentage By Parent	75.00%		75.00%
Related Party Number Of Stores	5		5
Related Party Transaction Related Party Share Of Profit (Less Than $1 Million For The Three Month Periods Ended February 28, 2015 and 2014)	1	1	1	1
Lease Expiration Date			Mar. 31, 2016
Related Party Transaction Rent Expense (Less Than $1 Million For the Three and Six Month Periods Ended February 28, 2015 and 2014)	$ 1	$ 1	$ 1	$ 1