Summary of Significant Accounting Polices - EPS (Details) - shares shares in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Net income (loss) per share:
Weighted average shares - basic	31,299	30,495	27,229
Effect of dilutive securities		111	122
Weighted average shares - diluted	31,299	30,606	27,351
Number of anti-dilutive securities	1,064