Equity and Noncontrolling Interests - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Mar. 31, 2016		Mar. 31, 2015		Mar. 31, 2016	Mar. 31, 2015		Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, end of period		$ (1,039)		$ (1,076)		$ (1,039)	$ (1,076)		$ (1,057)
Realized and unrealized gains (losses) on derivatives
Current period changes in fair value		5		7		2	(3)
Foreign Currency Translation Adjustments
Foreign currency translation adjustments
Balance at beginning of period		(1,207)		(599)		(1,047)	(248)
Aggregate adjustment for the period		175		(481)		15	(832)
Balance at end of period		(1,032)		(1,080)		(1,032)	(1,080)
Aggregate adjustment for period, tax		5		(4)		1	(2)
Realized and Unrealized Gains (Losses) on Derivatives
Realized and unrealized gains (losses) on derivatives
Balance at beginning of period		(8)		(6)		(7)	4
Current period changes in fair value		5		4		1	(5)
Reclassification to income		(1)		2		2	1
Balance at end of period		(4)		0		(4)	0
Current period changes in fair value, derivatives, tax		1		1		1	(4)
Reclassification to income, derivatives, tax		0	[1]	1	[1]	1	1	[1]
Pension And Postretirement Plans
Pension and postretirement plans
Balance at beginning of period		(3)		4		(3)	7
Reclassification to income		(1)		(1)		(1)	(4)
Pension and postretirement plans		(1)		(1)		(1)	(1)
Balance at end of period		(3)		4		(3)	4
Reclassification to income, pension and postretirement, tax	[2]	0		0		0	(1)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax, Portion Attributable to Parent		$ 0		$ 0		$ 0	$ 0

[1] Refer to Note 15, "Derivative Instruments and Hedging Activities," of the notes to consolidated financial statements for disclosure of the line items on the consolidated statements of income affected by reclassifications from AOCI into income related to derivatives

[2] Refer to Note 11, "Pension and Postretirement Plans," of the notes to consolidated financial statements for disclosure of the components of the Company's net periodic benefit costs associated with its defined benefit pension and postretirement plans. For the three and six months ended March 31, 2016, the amounts reclassified from AOCI into income for pension and postretirement plans were primarily recorded in selling, general and administrative expenses on the consolidated statements of income. For the three and six months ended March 31, 2015, the amounts reclassified from AOCI into income for pension and postretirement plans were primarily recorded in selling, general and administrative expenses and income from discontinued operations, net of tax on the consolidated statements of income.