Leases - Assets and Liabilities Lease (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Operating lease right-of-use assets, net	$ 268	$ 273
Operating lease liabilities, current	43	39
Operating lease liabilities, noncurrent	287	299
Operating lease liabilities	$ 330	$ 338
Operating lease, weighted average remaining lease term	8 years	8 years
Operating lease, weighted average discount rate, percent	4.69%	4.58%