Stock-based Compensation Summary of Stock Appreciation Rights Activity (Details) (Stock Appreciation Rights (SARs), USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2013
Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted Average SAR Price, Outstanding beginning balance	$ 26.93
Weighted Average SAR Price, Granted	$ 27.85
Weighted Average SAR Price, Exercised	$ 23.67
Weighted Average SAR Price, Forfeited or expired	$ 28.42
Weighted Average SAR Price, Outstanding ending balance	$ 27.94
Weighted Average SAR Price, Exercisable	$ 27.44
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding Roll Forward]
Shares Subject to SAR, Outstanding beginning balance	3,775,878
Shares Subject to SAR, Granted	1,018,650
Shares Subject to SAR, Exercised	(923,570)
Shares Subject to SAR, Forfeited or expired	(126,167)
Shares Subject to SAR, Outstanding ending balance	3,744,791
Shares Subject to SAR, Exercisable	1,884,356
Weighted Average Remaining Contractual Life (years), Outstanding	6 years 3 months 19 days
Weighted Average Remaining Contractual Life (years), Exercisable	4 years 3 months 19 days
Aggregate Intrinsic Value SAR, Outstanding	$ 51
Aggregate Intrinsic Value SAR, Exercisable	$ 27