Business Restructuring Charges (Details) $ in Millions	12 Months Ended
	Sep. 30, 2015 USD ($)
Restructuring Reserve [Roll Forward]
Balance at September 30, 2014	$ 0
Assumed liability	19
Charged to expense	271
Cash payments	(94)
Non-cash settlements	(44)
Other adjustments	(91)
Balance at September 30, 2015	62
Employee Termination
Restructuring Reserve [Roll Forward]
Balance at September 30, 2014	0
Assumed liability	19
Charged to expense	126
Cash payments	(74)
Non-cash settlements	0
Other adjustments	(9)
Balance at September 30, 2015	62
Share-Based Compensation
Restructuring Reserve [Roll Forward]
Balance at September 30, 2014	0
Assumed liability	0
Charged to expense	44
Cash payments	0
Non-cash settlements	(44)
Other adjustments	0
Balance at September 30, 2015	0
Other
Restructuring Reserve [Roll Forward]
Balance at September 30, 2014	0
Assumed liability	0
Charged to expense	102
Cash payments	(20)
Non-cash settlements	0
Other adjustments	(81)
Balance at September 30, 2015	$ 0