Share-Based Compensation - 2009 Stock-Based Incentive Compensation Plan (Details) - USD ($)	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Options
Outstanding at the beginning of the period (in shares)	550,834	550,834
Outstanding at the end of the period (in shares)	104,500	550,834	550,834
2009 Plan
Share-Based compensation
Number of shares of common stock reserved for awards	1,200,000
2009 Plan | Options
Options
Outstanding at the beginning of the period (in shares)	550,834	550,834	556,834
Exercised (in shares)	(546,334)
Cancelled (in shares)		0	(6,000)
Outstanding at the end of the period (in shares)	4,500	550,834	550,834
Vested and expected to vest (in shares)	4,500
Options exercisable at the end of the period (in shares)	4,500
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 3.32	$ 3.32	$ 3.32
Exercised (in dollars per share)	3.31
Cancelled (in dollars per share)		0.00	3.78
Outstanding at the end of the period (in dollars per share)	3.78	$ 3.32	$ 3.32
Vested and expected to vest (in dollars per share)	3.78
Options exercisable at the end of the period (in dollars per share)	$ 3.78
Aggregate Intrinsic Value
Outstanding at the beginning of the period (in dollars)	$ 761,767	$ 15,000	$ 177,043
Exercised (in dollars)	1,926,782	0	0
Outstanding at the end of the period (in dollars)	13,770	$ 761,767	$ 15,000
Vested and expected to vest (in dollars)	13,770
Options exercisable at the end of the period (in dollars)	$ 13,770
2009 Plan | Performance-based Award | Employee
Share-Based compensation
Maximum award (in shares)	300,000