Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021
Operating Leases
Operating lease right-of-use assets	$ 258	$ 268
Operating lease liabilities, current	43	43
Operating lease liabilities, noncurrent	275	287
Total operating lease liabilities	$ 318	$ 330
Weighted Average Remaining Lease Term
Operating leases	7 years	8 years
Weighted Average Discount Rate
Operating leases	4.70%	4.69%