Commitments and Contingencies Narrative (Details) - USD ($)	Dec. 31, 2018	Sep. 30, 2018
Loss Contingencies [Line Items]
Special Assessment Bond	$ 82,900,000
Restricted cash	16,100,000	$ 16,200,000
Standby Letters of Credit [Member] | Keybank National Association [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	$ 15,300,000