Subsequent Events (Details) - USD ($)	Jul. 25, 2016	Jun. 24, 2016	Jun. 30, 2016	Sep. 30, 2015
Subsequent Event [Line Items]
Long-term debt			$ 1,374,780,000	$ 1,678,268,000
6.5% Senior Notes | Senior Notes
Subsequent Event [Line Items]
Authorized repurchase amount		$ 150,000,000
Principal amount repurchased			159,300,000
Long-term debt			$ 489,780,000	$ 648,268,000
Subsequent Event | 6.5% Senior Notes | Senior Notes
Subsequent Event [Line Items]
Principal amount repurchased	$ 42,000,000
Principle amount repurchased, purchase price	31,500,000
Principle amount repurchased, total cost	33,000,000
Long-term debt	$ 448,700,000
Discount	25.00%