Retirement and Deferred Compensation Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	50.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	6.00%
Deferred Compensation Plan, Annual Vesting Percent	100.00%
Deferred Compensation Arrangement with Individual, Requisite Service Period	5 years
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 2.4	$ 2.0	$ 1.1
Total matching contributions forfeited by plan participants during period	$ 0.5	$ 0.4	$ 0.5
Minimum
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employee Deferral Rate	1.00%
Maximum
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employee Deferral Rate	80.00%