Stock-based Compensation Expense - Summary of Restricted Stock Activity outside of 2019 and 2016 Plan (Details) - Grants Outside of 2016 Stock Incentive Plan and 2019 Stock Incentive Plan - Restricted Stock	3 Months Ended
	Mar. 31, 2021 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Unvested, Beginning balance | shares	42,858
Number of Shares, Vested | shares	(14,286)
Number of Shares, Unvested, Ending balance | shares	28,572
Weighted Average Grant Date Fair Value, Unvested, Beginning balance	$ 2.93
Weighted Average Grant Date Fair Value, Granted	0
Weighted Average Grant Date Fair Value, Vested	2.93
Weighted Average Grant Date Fair Value, Unvested, Ending balance	$ 2.93