Equity and Noncontrolling Interests Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated other comprehensive loss, end of period		$ (434)	$ (776)	$ (795)
Realized and unrealized gains (losses) on derivatives
Divestiture of Power Solutions		(18)	8	6
Foreign Currency Translation
Foreign currency translation adjustments
Balance at beginning of period		(778)	(785)	(939)
Aggregate adjustment for the period		357	7	(325)
Balance at end of period		(421)	(778)	(785)
Aggregate adjustment for the period, tax		0	1	0
Realized And Unrealized Gains Losses On Derivatives
Realized and unrealized gains (losses) on derivatives
Balance at beginning of period		2	(2)	(13)
Current period changes in fair value		(8)	3	(1)
Reclassification to income	[1]	(11)	1	8
Balance at end of period		(17)	2	(2)
Reclassification to income, tax		(3)	0	2
Changes in fair value, tax		5	1	(1)
Unrealized Gain Loss On Marketable Securities
Realized and unrealized gains (losses) on marketable securities
Balance at beginning of period		0	0	8
Adoption of ASU		0	0	0
Balance at end of period		0	0	0
Pension And Other Postretirement Benefit Plans Assets
Pension and postretirement plans
Balance at beginning of period		0	(8)	(2)
Balance at end of period		4	0	(8)
Reclassification to income		3	1	0
Other changes		7	9	6
Reclassification to income, tax		0	(1)	0
Other changes (tax)		(1)	4	0
Power Solutions
Foreign currency translation adjustments
Divestiture of Power Solutions		0	0	479
Realized and unrealized gains (losses) on derivatives
Divestiture of Power Solutions		0	0	4
Power Solutions | Realized And Unrealized Gains Losses On Derivatives
Realized and unrealized gains (losses) on derivatives
Reclassification to income, tax		0	0	1
Accounting Standards Update 2016-01 [Member]
Realized and unrealized gains (losses) on marketable securities
Balance at beginning of period			8
Adoption of ASU				8
Balance at end of period				8
Accumulated Other Comprehensive Income (Loss) | Accounting Standards Update 2016-01 [Member]
Realized and unrealized gains (losses) on marketable securities
Balance at beginning of period	[2]	$ 0	0	(8)
Adoption of ASU	[2]		0	0
Balance at end of period	[2]		$ 0	$ 0

[1] Refer to Note 11, "Derivative Instruments and Hedging Activities," of the notes to consolidated financial statements for disclosure of the line items in the consolidated statements of income affected by reclassifications from AOCI into income related to derivatives.

[2] The Company adopted ASU 2016-01, "Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities" effective October 1, 2018 and, as a result, reclassified $8 million of unrealized gains on marketable securities to retained earnings.