Leases - Schedule of Balance Sheet and Supplemental Operating Lease Information (Details) $ in Millions	3 Months Ended
	Dec. 31, 2019 USD ($)
Balance Sheet Information:
Operating lease right-of-use assets, net	$ 340
Operating lease liabilities	$ 373
Supplemental Information:
Weighted-average remaining lease term	8 years 3 months 18 days
Weighted-average discount rate	2.49%
Supplemental Cash Flow Information:
Cash paid for amounts included in the measurement of lease liabilities	$ 17
Lease liabilities arising from obtaining right-of-use assets	8
Operating Lease Expense
Operating lease costs, net	$ 18