Leases - Summary of Other Lease Information (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2020 USD ($)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows – operating leases	$ 183,808
Operating cash flows – finance leases	36
Financing cash flows – finance leases	34
Supplemental non-cash information on lease liabilities:
Lease assets obtained in exchange for new operating lease liabilities	204,245
Lease assets obtained in exchange for new finance lease liabilities	$ 4
Weighted-average remaining lease term (in years):
Operating leases	5 years 1 month 6 days
Finance leases	3 years 9 months 18 days
Weighted-average discount rate:
Operating leases	4.40%
Finance leases	0.30%