Stock-Based Compensation - Narrative (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended						9 Months Ended		69 Months Ended
	Oct. 31, 2020 USD ($) shares	Sep. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2020 USD ($) shares	Mar. 31, 2020 USD ($) shares	Sep. 30, 2019 USD ($) $ / shares shares	Jun. 30, 2019 USD ($) shares	Mar. 31, 2019 USD ($) shares	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2020 shares	Apr. 29, 2020 shares	Apr. 28, 2020
Stock-Based Compensation
Shares issued under the Employee Stock Purchase Plan (in shares) | $		$ 309	$ 257	$ 224	$ 275	$ 211	$ 218
Employee stock
Stock-Based Compensation
Common stock available for issuance (in shares)		1,000,000						1,000,000		1,000,000
Common stock granted since inception (in shares)										693,498
Employee stock | Subsequent event
Stock-Based Compensation
Shares purchased during period (in shares)	20,591
Shares issued under the Employee Stock Purchase Plan (in shares) | $	$ 300
Service-based stock options
Stock-Based Compensation
Expiration period								10 years
Vesting period								4 years
Granted (in shares)		28,000			111,600			1,324,890	1,750,110
Weighted average grant-date fair value (in dollars per share) | $ / shares		$ 10.81			$ 13.28			$ 8.70	$ 12.77
Service-based stock options | Nonemployee directors
Stock-Based Compensation
Expiration period								10 years
Vesting period								1 year
Restricted Stock Units (RSUs)
Stock-Based Compensation
Vesting period								4 years
Restricted stock units granted (shares)								196,836	186,922
Weighted-average grant date fair value (in usd per share) | $ / shares								$ 11.41	$ 17.71
Grant-date fair value of restricted stock units granted | $								$ 2,200	$ 3,300
Shares vested in period (shares)								32,840
Restricted stock withheld for employee tax remittance (in shares)								13,872
Restricted Stock Units (RSUs) | Nonemployee directors
Stock-Based Compensation
Vesting period								1 year
Common Stock
Stock-Based Compensation
Shares purchased during period (in shares)		44,000	32,000	20,000	18,000	14,000	19,000
Shares issued under the Employee Stock Purchase Plan (in shares) | $		$ 309	$ 257	$ 224	$ 275	$ 211	$ 218
Restricted stock withheld for employee tax remittance (in shares)				14,000
Prior Plans
Stock-Based Compensation
Awards available for future grant under the Plan (in shares)		0						0		0
Omnibus Incentive Plan 2019
Stock-Based Compensation
Awards available for future grant under the Plan (in shares)		4,553,487						4,553,487		4,553,487
Ratio of full value awards against share reserve											1.4	1.25
Omnibus Incentive Plan 2019 | Common Stock
Stock-Based Compensation
Increase in number of shares available for issuance (shares)											2,400,000