Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period			$ 4,394
Other comprehensive income (loss) before reclassification adjustments	$ (6)	$ 30	16	$ 179
Amounts reclassified from AOCI	(9)	(11)	(29)	(21)
Other comprehensive (loss) income	(15)	19	(13)	158
Balance, end of period	4,690	4,373	4,690	4,373
Total
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(254)	(241)	(256)	(380)
Balance, end of period	(269)	(222)	(269)	(222)
Postretirement Benefit Plans
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	16	14	17	14
Other comprehensive income (loss) before reclassification adjustments	0	0	0	0
Amounts reclassified from AOCI	0	(1)	(1)	(1)
Other comprehensive (loss) income	0	(1)	(1)	(1)
Balance, end of period	16	13	16	13
Derivative Instruments
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	4	15	26	37
Other comprehensive income (loss) before reclassification adjustments	4	22	1	10
Amounts reclassified from AOCI	(9)	(10)	(28)	(20)
Other comprehensive (loss) income	(5)	12	(27)	(10)
Balance, end of period	(1)	27	(1)	27
Foreign Currency
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(274)	(270)	(299)	(431)
Other comprehensive income (loss) before reclassification adjustments	(10)	8	15	169
Amounts reclassified from AOCI	0	0	0	0
Other comprehensive (loss) income	(10)	8	15	169
Balance, end of period	$ (284)	$ (262)	$ (284)	$ (262)