Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Tax benefit at federal statutory rate	$ (18,573,000)	$ (3,384,000)	$ (1,367,000)
State taxes	(2,748,000)	(232,000)	(90,000)
Research tax credits	(475,000)	(427,000)	(165,000)
Change in valuation allowance	15,062,000	3,958,000	1,694,000
Change in fair value of convertible notes	5,756,000	0	0
Other	978,000	85,000	(72,000)
Expense/(Benefit) for income taxes	$ 0	$ 0	$ 0