Stockholder's Equity (Narrative) (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2007
Repurchase authorization, shares	1.1	1.6	0	10.0
Repurchase authorization, amount	$ 36	$ 50
Shares remaining available for repurchase under the current authorization	1.6
Cash dividends paid	$ 0.76	$ 0.72	$ 0.72