Nature of Operations and Summary of Significant Accounting Policies - Calculation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Accounting Policies [Abstract]
Net income (loss)	$ 908	$ (716)	$ 1,468	$ (3,907)
Weighted-average shares outstanding - basic (in shares)	41,022	38,926	40,817	38,583
Common stock equivalents (in shares)	1,006	0	1,213	0
Weighted-average shares outstanding - diluted (in shares)	42,028	38,926	42,030	38,583
Net income (loss) per share:
Basic (in dollars per share)	$ 0.02	$ (0.02)	$ 0.04	$ (0.10)
Diluted (in dollars per share)	$ 0.02	$ (0.02)	$ 0.03	$ (0.10)