Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Contingency [Line Items]
Income tax expense	$ (2,780)	$ 194	$ (1,540)	$ 284
Reversal of accrued taxes, interest and penalties	3,100		3,100
Unrecognized tax benefits that would impact effective tax rate	0		0			$ 4,200
Unrecognized tax benefits, income tax penalties and interest accrued	$ 600		$ 600			$ 2,600
Minimum
Income Tax Contingency [Line Items]
Number of years open for tax examinations			3 years
Maximum
Income Tax Contingency [Line Items]
Number of years open for tax examinations			5 years
Scenario, Forecast
Income Tax Contingency [Line Items]
Statutory tax rate					24.50%