Long-Term Debt - Summary of Long-Term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Sep. 30, 2014
Debt Instrument [Line Items]
Long-term Debt	$ 1,716,247	$ 1,742,122
Senior Notes | 6.5% Senior Notes
Debt Instrument [Line Items]
Stated interest rate	6.50%	6.50%
Long-term Debt	$ 656,247	$ 657,122
Revolving Credit Facility
Debt Instrument [Line Items]
Long-term Debt	$ 1,060,000	$ 1,085,000