Employee Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Defined contribution plan recognized expenses	$ 2.8	$ 3.9	$ 5.9
Deferred compensation, retirement age	65 years
Deferred compensation requisite service period	10 years
Deferred compensation recorded liability	$ 0.3
Cash surrender value of life insurance	$ 4.7
Minimum
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Age older but less than	55 years
Maximum
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Age older but less than	65 years
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	6.4
Deferred compensation liabilities	5.0
Retiree medical plan
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Unfunded liability	1.1	1.4
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
Company owned life insurance policies | Deferred compensation plan
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred compensation plan assets	$ 5.6