Goodwill and Other Intangible Assets (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Jun. 30, 2012	Sep. 30, 2011
Goodwill And Other Intangible Assets [Line Items]
Finite-lived intangible assets	$ 3	$ 3
Useful life of intangible assets	12 years
Minimum
Goodwill And Other Intangible Assets [Line Items]
Useful life of intangible assets	6 years
Maximum
Goodwill And Other Intangible Assets [Line Items]
Useful life of intangible assets	14 years
Amortization of intangible assets, year one	1
Amortization of intangible assets, year two	1
Amortization of intangible assets, year three	1
Amortization of intangible assets, year four	1
Amortization of intangible assets, year five	$ 1