Stock-based Compensation - Stock Option and Restricted Stock Unit Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Shares
Beginning Balance (in shares)	10,098,929
Granted (in shares)	3,367,777
Exercised (in shares)	(34,608)
Forfeited or expired (in shares)	(365,942)
Expired (in shares)	(842,519)
Ending Balance (in shares)	12,223,637	10,098,929
Exercisable (in shares)	7,892,753
Vested and expected to vest (in shares)	11,346,207
Weighted-Average Exercise Price
Beginning Balance (in dollars per share)	$ 18.58
Granted (in dollars per share)	4.97
Exercised (in dollars per share)	3.73
Forfeited or expired (in dollars per share)	9.49
Expired (in dollars per share)	19.12
Ending Balance (in dollars per share)	15.11	$ 18.58
Exercisable (in dollars per share)	18.92
Vested and expected to vest (in dollars per share)	$ 15.59
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-average remaining contractual term, Outstanding	6 years 8 months 12 days	6 years 6 months
Weighted-average remaining contractual term, Exercisable	5 years 7 months 6 days
Weighted-average remaining contractual term, Vested and expected to vest	6 years 6 months
Aggregate intrinsic value, Outstanding	$ 16,974
Aggregate intrinsic value, Exercisable	4,509
Aggregate intrinsic value, Vested and expected to vest	$ 14,692
Weighted-Average Grant Date Fair Value
Common stock, shares issued (in shares)	34,608	120,900	332,767
Cash proceeds from exercise of stock options	$ 100	$ 200	$ 5,800
Weighted-average grant-date fair value of options granted (in dollars per share)	$ 3.83	$ 6.84	$ 15.20
Share-based compensation arrangement by share-based payment award, options, exercises in period, intrinsic value	$ 100	$ 600	$ 3,300
Fair value of shares vested	16,400	$ 19,600	$ 20,200
Unrecognized compensation cost related to non-vested stock-based compensation arrangements	$ 19,500
Unrecognized compensation expense recognition period	1 year 2 months 12 days
Stock Incentive Plan 2013
Shares
Ending Balance (in shares)	11,805,515
Weighted-Average Exercise Price
Ending Balance (in dollars per share)	$ 15.45
Restricted Stock Units
Shares
Beginning Balance (in shares)	415,084
Granted (in shares)	707,635
Exercised (in shares)	(135,396)
Forfeited (in shares)	(81,709)
Ending Balance (in shares)	905,614	415,084
Weighted-Average Grant Date Fair Value
Beginning Balance (in dollars per share)	$ 8.83
Granted (in dollars per share)	4.88
Exercised (in dollars per share)	8.32
Forfeited or expired (in dollars per share)	7.17
Ending Balance (in dollars per share)	$ 5.97	$ 8.83
Unrecognized compensation expense recognition period	1 year 2 months 12 days
Awards granted in period (in shares)	707,635
Total unrecognized compensation cost	$ 2,300
Restricted Stock Units | Stock Incentive Plan 2013
Shares
Ending Balance (in shares)	854,114