Leases - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2021
Lessee, Lease, Description [Line Items]
Operating leases, rent expense	$ 119.0
Lessee, operating lease, lease not yet commenced, liability		$ 24.0
Lessee, finance lease, lease not yet commenced, liability		$ 10.0
Minimum
Lessee, Lease, Description [Line Items]
Lease term		1 year
Maximum
Lessee, Lease, Description [Line Items]
Lease term		16 years