Line of Credit (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Oct. 04, 2017
Letter of Credit
Line of Credit Facility [Line Items]
Line of credit, expiration date	Oct. 04, 2022
Letter of Credit | Minimum
Line of Credit Facility [Line Items]
Line of credit, expiration period	90 days
Line of Credit | Credit Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	$ 75.0		$ 75.0
Outstanding line of credit	0.0	$ 0.0
Deferred finance costs	0.3	$ 0.4
Line of credit, remaining borrowing capacity	$ 43.6
Line of Credit | Credit Agreement | Letter of Credit
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity			7.5
Secured Debt | Senior Secured Term Loan Facility
Line of Credit Facility [Line Items]
Face amount			$ 200.0