Stockholders' Equity (Details) (USD $) In Millions, except Share data	3 Months Ended									12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2009	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009	Sep. 30, 2008
Stockholders' Equity (Textuals) [Abstract]
Common stock, shares issued		323,243,170				322,478,467				323,243,170	322,478,467
Common stock, shares outstanding		316,043,099				318,823,234				316,043,099	318,823,234	317,480,886	316,660,275
Preferred stock, shares issued
Preferred stock, shares outstanding
Amount remaining under stock repurchase authorization										$ 100
Cash dividends declared per common share	$ 0.0375	$ 0.0375	$ 0.0375	$ 0.0375	$ 0.0375	$ 0.0375	$ 0.0375	$ 0.0375	$ 0.0375	$ 0.15	$ 0.15	$ 0.15
Common stock repurchased			3,544,838							3,544,838
Total cost of shares repurchased			$ 38.6							$ 38.6
Stock Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock reserved for issuance		34,800,000								34,800,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock reserved for issuance		3,700,000								3,700,000