Profit Sharing Plan (Details) - Multiple employer 401(k) profit sharing plan $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2020 USD ($) year	Mar. 31, 2019 USD ($)
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, requisite service period			1 year
Defined contribution plan, minimum age requirement (years of age) | year			21
Contributions by the Company | $	$ 1.6	$ 1.1	$ 3.3	$ 2.9