Debt - Summary (Details) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Mar. 11, 2020	Feb. 29, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt
Minimum amount to be maintained in cash and cash equivalents	$ 3,000
Loan origination costs			$ 1,300
Initial fee paid to lender			700
Loss on extinguishment of debt			(2,757)
Term loan
Debt
End of term fee			$ 5,000	$ 35,000
Loan Agreement | Term loan
Debt
Maximum borrowing capacity					$ 75,000
Principal amount of advances outstanding	35,000
Interest rate (as a percent)			9.80%
Fee due at maturity, as a percentage of aggregate advances			6.95%
The amount in excess of which prepayments may be made			$ 5,000
Repayment of debt	$ 30,000		30,000
Percent of net product revenue sales target	70.00%	80.00%
Minimum liquidity requirement		$ 40,000
Maximum value of lender option to purchase equity securities			2,000
End of term loan charge payment	$ 2,100
End of term loan charge	$ 300,000	$ 600,000
Loss on extinguishment of debt			2,700
End of term fee			$ 5,000
Loan Agreement | Term loan | Prime rate
Debt
Variable rate basis			interest minus 5.50%
Variable interest rate margin (as a percent)			9.80%
Variable rate adjustment (as a percent)			5.50%
Loan Agreement | Term loan | Initial Advance
Debt
Principal amount of advances outstanding					25,000
Loan Agreement | Term loan | Tranche 7 Advance
Debt
Maximum borrowing capacity					$ 5,000
Additional tranches			$ 5,000
Loan Agreement | Term loan | Prepayment during the first 12 months following initial closing
Debt
Prepayment penalty as a percentage of the amount being repaid			3.00%
Loan Agreement | Term loan | Prepayment after the first 12 months following initial closing but before 24 months
Debt
Prepayment penalty as a percentage of the amount being repaid			2.00%
Loan Agreement | Term loan | Prepayment after the first 24 months following initial closing but before maturity
Debt
Prepayment penalty as a percentage of the amount being repaid			1.00%