Debt and Other Financing Activities - U.S. Accounts Receivable Sales Program - Additional Information (Details) - U.S. Accounts Receivable Sales Program [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2025
Disclosure Of Sales Program Of Receivable [Line Items]
Loss on sale of receivables		$ 1	$ 1	$ 2
Sales against the buyers limit			60		$ 59
Maximum limit of receivables can transfer			60		59
Amount transferred in accounts receivable			72		75
Gross cash proceeds received for accounts receivable transferred			77	189
Cash proceeds collected			76	200
Increase (decrease) in account receivable sales volume			1	$ (11)
Maximum [Member]
Disclosure Of Sales Program Of Receivable [Line Items]
Loss on sale of receivables	$ 1
Recorded liabilities related to service obligations and limited guarantee	$ 1		$ 1		$ 1