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Equity and Stock-Based Compensation - Additional Information (Details) - USD ($)				3 Months Ended	12 Months Ended				13 Months Ended	84 Months Ended	120 Months Ended
	Feb. 16, 2021	Feb. 10, 2020	Nov. 29, 2018	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2000	Dec. 31, 2019	Dec. 31, 2015	Dec. 31, 2014	Apr. 30, 2007
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, par value					$ 0.01	$ 0.01
Total cost of shares repurchased and retired						$ 2,000,000
Stock-based compensation expense					$ 401,000	$ 326,000	$ 573,000
Compensation cost on non-vested stock options not yet recognized					$ 400,000
Compensation cost, expected weighted-average recognition period					1 year 5 months 26 days
Shares available to grant					1,014,754
2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available to grant					929,820
2007 Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available to grant												500,000
Number of additional shares authorized										2,500,000
Non-Employee Directors Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available to grant					84,934
Non-Employee Directors Stock Option Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized											400,000
Share-based compensation, shares issued								100,000
2019 Stock Repurchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program period			1 year
Authorized stock repurchase amount			$ 4,000,000
Shares repurchased and retired during the period									0
2020 Stock Repurchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program period		1 year
Authorized stock repurchase amount		$ 4,000,000
Shares repurchased and retired during the period				366,000
Total cost of shares repurchased and retired				$ 2,000,000.0
Average price per share of shares repurchased				$ 5.46
2021 Stock Repurchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program period	1 year
Authorized stock repurchase amount	$ 4,000,000
Shares repurchased and retired during the period					0