Stockholders' Equity - Nonvested Restricted Stock Unit Activity (Details) - Restricted Stock Units - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 28, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Shares
Beginning balance (in shares)		2,207,242	1,250,000	0
Granted (in shares)		1,810,017	1,295,632	1,250,000
Vested (in shares)		(563,711)	(251,042)
Forfeited or expired (in shares)		(134,908)	(87,348)
Ending balance (in shares)		3,318,640	2,207,242	1,250,000
Weighted Average Grant Due Fair Value
Beginning balance		$ 7,302	$ 3,054	$ 0
Granted		5,400	5,250	3,054
Vested	$ (1,966)	(2,261)	(697)	(3,054)
Forfeited		(435)	(305)
Ending balance		$ 10,006	$ 7,302	$ 3,054