Goodwill and Other Intangible Assets - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of other intangible assets	$ 20	$ 11	$ 38	$ 25
Future amortization expense, 2014	89		89
Future amortization expense, 2015	81		81
Future amortization expense, 2016	76		76
Future amortization expense, 2017	67		67
Future amortization expense, 2018	$ 58		$ 58