Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Income Tax Contingency [Line Items]
Federal net operating loss carryforwards	$ 252,500,000
State net operating loss carryforwards	31,600,000
Alternative minimum tax credit	9,800,000
General business credits	7,100,000
Income tax expense (benefit) from continuing operations	16,498,000	$ (324,569,000)	$ (41,797,000)
Adjustment from settlement with tax authority		26,800,000
Recognition of unrecognized tax benefits		14,300,000
Pre-tax income required to realize deferred tax assets prior to expiration	760,000,000
Valuation allowances and reserves, adjustments		335,200,000
Deferred tax asset valuation allowance	66,265,000	57,659,000
Unrecognized tax benefits	4,541,000	4,721,000	$ 4,616,000	$ 17,464,000
Accrued interest and penalties	300,000	$ 400,000
Uncertain tax positions to be reserved within twelve months	0
State and Local Jurisdiction
Income Tax Contingency [Line Items]
Valuation allowances and reserves, adjustments	$ 8,600,000