Employee Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined contribution plan recognized expenses	$ 3.1	$ 3.2	$ 2.8
Deferred compensation, retirement age	65 years
Deferred compensation requisite service period	10 years
Deferred compensation recorded liability	$ 0.1
Cash surrender value of life insurance	$ 3.3
Maximum
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Age older but less than	65 years
Retiree medical plan
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred compensation requisite service period	10 years
Unfunded liability	$ 0.9	0.9
Retiree medical plan | Minimum
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Age older but less than	55 years
Retiree medical plan | Maximum
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Net periodic postretirement benefit cost (less than)	$ 0.1	$ 0.1	$ 0.1
Deferred compensation plan
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Percentage of employee based salary permitted for deferral under the plan	50.00%
Percentage of employee annual bonus permitted for deferral under the plan	100.00%
Deferred compensation expense adjustment	$ 0.1
Deferred compensation plan assets	7.4
Deferred compensation liability	6.6
Deferred compensation plan | Company owned life insurance policies
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred compensation plan assets	$ 7.2