Subsequent Event - Additional Information (Detail) (USD $)	3 Months Ended		1 Months Ended	3 Months Ended
	Oct. 31, 2012	Sep. 30, 2012	Nov. 30, 2012 Subsequent Event [Member]	Oct. 31, 2012 SDG [Member]	Oct. 31, 2012 SDG [Member] Subsequent Event [Member]
Subsequent Event [Line Items]
Business acquisition cost					$ 365,000,000
Senior notes, face value	350,000,000	350,000,000
Third-party sales for previous fiscal year				1,750,000,000
Sale commitment period			5 years
Estimated increment in sale			500,000,000
Purchase price allocated to cash	143,000,000
Acquired intangible assets	104,000,000
Estimated useful life	10 years
Acquired goodwill	78,000,000
Purchase price premium acquired	$ 40,000,000