Employee Benefit Plan (Details) (Savings Plan [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Savings Plan [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Defined contribution plan, percentage of employee's contributions matched by employer	50.00%
Defined contribution plan, percentage of employer contribution on employee's earnings	6.00%
Defined contribution plan, employers contribution, rate of vesting, percentage	25.00%
Defined contribution plan, vesting period	4 years
Matching contributions by employer	$ 5.1	$ 5.0	$ 4.9