Income Taxes (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Taxes
Income tax provision (benefit)		$ 10,535	$ (10,478)	$ (494,028)	$ (50,537)
Effective income tax rate (as a percent)		446.20%	31.20%	15472.20%	32.30%
U.S. federal statutory rate (as a percent)							35.00%
Income tax benefit related to new tax act	$ (700)	$ 10,400		$ (491,400)
Forecast
Income Taxes
U.S. federal statutory rate (as a percent)						24.50%