Equity and Noncontrolling Interests - Changes in Redeemable Noncontrolling Interests (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Stockholders' Equity Attributable to Redeemable Noncontrolling Interest [Roll Forward]
Beginning balance			$ 212
Ending balance	$ 251	$ 220	251	$ 220
Parent [Member]
Stockholders' Equity Attributable to Redeemable Noncontrolling Interest [Roll Forward]
Realized and unrealized gains (losses) on derivatives	6	(3)	9	(7)
Other	(31)	(114)	(78)	(341)
Redeemable Noncontrolling Interests [Member]
Stockholders' Equity Attributable to Redeemable Noncontrolling Interest [Roll Forward]
Beginning balance	237	202	212	194
Net income	17	12	48	43
Foreign currency translation adjustments	(3)	4	(1)	(16)
Realized and unrealized gains (losses) on derivatives	0	2	(2)	3
Dividends			(6)	(4)
Ending balance	251	220	251	220
Noncontrolling Interest [Member]
Stockholders' Equity Attributable to Redeemable Noncontrolling Interest [Roll Forward]
Other	$ 0	$ 0	$ 0	$ 0