Income Taxes - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Income Tax Contingency [Line Items]
Federal net operating loss carryforwards		$ 241,300,000
State net operating loss carryforwards		31,700,000
Alternative minimum tax credit		9,600,000
General business credits		14,500,000
Income tax expense (benefit) from continuing operations		2,696,000	$ 16,498,000	$ (324,569,000)
Valuation allowances and reserves, adjustments			8,600,000	335,200,000
Pre-tax income required to realize deferred tax assets prior to expiration		721,900,000
Deferred tax asset valuation allowance	$ 66,265,000	65,159,000	66,265,000	57,700,000
Unrecognized tax benefits	4,541,000	3,804,000	4,541,000	$ 4,721,000	$ 4,615,000
Accrued interest and penalties	339,500	0	339,500
Uncertain tax positions to be reserved within twelve months		17,000
State and Local Jurisdiction
Income Tax Contingency [Line Items]
Valuation allowances and reserves, adjustments	$ 8,600,000	$ 3,500,000	$ 8,600,000