Stockholders' Equity (Details) (USD $)	0 Months Ended	3 Months Ended						12 Months Ended
	Aug. 01, 2013	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common stock, shares issued		330,143,689		328,092,047				330,143,689	328,092,047
Common stock, shares outstanding		322,943,618		320,891,976				322,943,618	320,891,976
Amount of stock repurchase authorization	$ 100,000,000
Amount remaining under stock repurchase authorization		100,000,000
Dividends, Common Stock [Abstract]
Cash dividends declared per common share			$ 0.0375	$ 0.0375	$ 0.0375	$ 0.0375	$ 0.0375	$ 0.1875	$ 0.15	$ 0.15
Debt Conversion, Converted Instrument, Shares Issued								77.18004	76.5697
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities								38,600,000	38,300,000	0
Stock Compensation Plan [Member]
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common Stock reserved for issuance		26,500,000						26,500,000
Employee Stock Purchase Plan [Member]
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common Stock reserved for issuance		3,600,000						3,600,000
Accelerated Dividend [Member]
Dividends, Common Stock [Abstract]
Cash dividends declared per common share								$ 0.15
Convertible Senior Note One [Member]
Dividends, Common Stock [Abstract]
Debt Instrument, Face Amount		$ 1,000						$ 1,000
Debt Instrument, Convertible, Conversion Price		$ 12.96		$ 13.06				$ 12.96	$ 13.06