Supplemental Financial Information - Summary of Accounts Receivable (Details) - USD ($) $ in Millions	Mar. 31, 2020	Sep. 30, 2019
Supplemental Financial Information [Abstract]
Trade	$ 342	$ 392
Other	16	15
Accounts receivable, gross	358	407
Accounts Receivable, Allowance for Credit Loss, Current	6	6
Accounts receivable, net	352	401
Loan to Franchisee [Member]
Accounts Receivable, non current [Line Items]
Accounts Receivable, Noncurrent, Not Past Due	$ 15	$ 0

Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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Supplemental Financial Information

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