Shareowners' Equity - Equity and Equity-Linked Repurchase Authorization (Details) - USD ($) shares in Millions		3 Months Ended		9 Months Ended
	Jun. 11, 2015	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2015	Jun. 30, 2014	May. 18, 2015	Feb. 28, 2015	Sep. 30, 2014
Class of Stock [Line Items]
Shares of common stock repurchased		1.1		2.3
Repurchase of common stock		$ 14,000,000		$ 30,000,000
Principal amount of convertible notes repurchased				159,000,000	$ 308,000,000
Equity and Equity-Linked Securities (Including Convertible Debt Securities) | M2016 Strategy
Class of Stock [Line Items]
Authorized repurchase of securities					$ 210,000,000
Authorized repurchase of securities, regardless of performance								$ 40,000,000
Convertible Notes Payable | 4.0 percent convertible notes due 2027
Class of Stock [Line Items]
Principal amount of convertible notes repurchased		$ 4,000,000	$ 15,000,000	$ 19,000,000
Interest rate		4.00%		4.00%			4.00%	4.00%
Repurchase of convertible notes				$ 4,000,000
Remaining authorized repurchase amount available		$ 161,000,000		$ 161,000,000
Convertible Notes Payable | 7.875% Convertible Notes Due 2026
Class of Stock [Line Items]
Interest rate		7.875%		7.875%				7.875%
Principal amount of convertible notes repurchased	$ 85,000,000
Repurchase of convertible notes	$ 139,000,000			$ 139,000,000
Remaining authorized repurchase amount available		$ 90,000,000		$ 90,000,000
Debt repurchase program, authorized amount						$ 175,000,000