Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2023
Related Party Transaction [Line Items]
Net sales to related parties	$ 3,750	$ 3,912	$ 7,410	$ 7,611
Purchases from related parties	3,520	3,662	6,934	7,130
Accounts receivable due from related parties	1,896		1,896		$ 1,874
Accounts payable due to related parties	2,512		2,512		2,526
Related Party
Related Party Transaction [Line Items]
Net sales to related parties	65	71	131	129
Purchases from related parties	110	$ 102	213	$ 216
Accounts receivable due from related parties	36		36		26
Accounts payable due to related parties	$ 67		$ 67		$ 67