Income Taxes - Reconciliations of the Statutory Federal Tax Rate to the Company's Effective Income Tax Rates (Details)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Reconciliations of the statutory federal tax rate to the Company's effective income tax rates
Statutory federal tax rate	35.00%	35.00%	35.00%
State tax rate, net of federal benefit	3.20%	2.70%	2.70%
Provision for uncertain income tax positions, net of federal benefit	2.10%	1.30%	2.40%
Settlements of uncertain income tax positions, net of federal effect	(13.00%)
Benefit of state net operating loss carryforwards, net of federal effect, recognized based on change in tax regulations		(3.30%)
Other	(1.70%)	(0.50%)	(0.90%)
Effective income tax rate	25.60%	35.20%	39.20%