Retirement Benefit Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2015	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]
Retiree medical liability	$ 463	$ 479
Pension liability	293	323
Other	16	16
Subtotal	772	818
Less: current portion (included in compensation and benefits, Note 14)	(43)	(43)
Retirement benefits	$ 729	$ 775