Trade Accounts Receivable Securitization and Sale Programs - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Feb. 28, 2013	Feb. 29, 2012	Feb. 28, 2013	Feb. 29, 2012
Trade Accounts Receivable Factoring Agreement
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Trade accounts receivable sold	$ 8,500,000	$ 22,000,000	$ 22,700,000	$ 43,400,000
Cash proceeds for sale of trade accounts receivable	8,500,000	22,000,000	22,700,000	43,400,000
Trade Accounts Receivable Sale Programs
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Trade accounts receivable sold	700,000,000	600,000,000	1,300,000,000	1,100,000,000
Cash proceeds for sale of trade accounts receivable	700,000,000	600,000,000	1,300,000,000	1,100,000,000
Asset-Backed Securitization Programs
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Percentage of trade accounts receivable sold to conduits by special purpose entities			100.00%
Trade accounts receivable sold	2,100,000,000	2,000,000,000	4,300,000,000	4,100,000,000
Cash proceeds for sale of trade accounts receivable	1,600,000,000	1,500,000,000	3,800,000,000	3,600,000,000
Deferred purchases price receivable	492,700,000	463,200,000	492,700,000	463,200,000
Pretax losses on sale of trade accounts receivable	1,000,000	1,200,000	2,100,000	3,000,000
North American Asset-Backed Securitization Program
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Maximum net cash proceeds available at any one time under asset-backed securitization program and sales program	300,000,000		300,000,000
Foreign Asset-Backed Securitization Program
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Maximum net cash proceeds available at any one time under asset-backed securitization program and sales program	200,000,000		200,000,000
200.0 Million Dollar Trade Accounts Receivable Sale Program | Trade Accounts Receivable Sale Programs
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Maximum net cash proceeds available at any one time under asset-backed securitization program and sales program	200,000,000		200,000,000
Trade accounts receivable sale agreement expiration date			May 28, 2013
200.0 Million Dollar Trade Accounts Receivable Sale Program | Trade Accounts Receivable Sale Programs | Before amendment
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Maximum net cash proceeds available at any one time under asset-backed securitization program and sales program	250,000,000		250,000,000
150.0 Million Dollar Trade Accounts Receivable Sale Program | Trade Accounts Receivable Sale Programs
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Maximum net cash proceeds available at any one time under asset-backed securitization program and sales program	150,000,000		150,000,000
Trade accounts receivable sale agreement expiration date			Nov. 28, 2013
40.0 Million Dollar Trade Accounts Receivable Sale Program | Trade Accounts Receivable Sale Programs
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Maximum net cash proceeds available at any one time under asset-backed securitization program and sales program	$ 40,000,000		$ 40,000,000
Trade accounts receivable sale agreement expiration date			Jun. 01, 2015
Minimum number of days notice required to cancel receivable sale agreements			30 days