Equity Incentive Awards - Narrative (Details) - USD ($)	12 Months Ended			84 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for future grants (in shares)	24,047,212			24,047,212
Options outstanding (in shares)	23,719,712			23,719,712
Stock-based compensation costs	$ 14,300,000	$ 11,500,000	$ 10,600,000
Future stock-based compensation cost for outstanding unvested awards	$ 26,800,000			$ 26,800,000
Future stock-based compensation cost for outstanding unvested awards, weighted-average recognition period	1 year 2 months 12 days
Issuance of treasury stock		0
Treasury Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of treasury stock		$ 6,321,000
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate value	$ 400,000			$ 400,000
Common stock reserved for issuance, exercisable (in shares)	8,280,000			8,280,000
Options outstanding (in shares)	18,705,000	12,349,000		18,705,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	0
Weighted average estimated grant date fair value (in dollars per share)	$ 1.78	$ 2.30	$ 4.85
Weighted average remaining contractual term of stock options outstanding	7 years 6 months
Weighted average remaining contractual term of stock options exercisable	5 years 7 months 6 days
Aggregate intrinsic value of exercisable stock options	$ 0			$ 0
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units outstanding (in shares)	5,015,000	2,748,000		5,015,000
Fair value of shares vested	$ 2,900,000	$ 2,900,000	$ 8,700,000
Granted (in shares)	4,199,000
Weighted average grant date fair value (in dollars per share)	$ 2.43
Restricted Stock Units (RSUs) | Officers and non-employee directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	64,256	74,416	32,192
Weighted average grant date fair value (in dollars per share)	$ 2.36	$ 1.77	$ 5.04
2017 Equity Incentive Plan and 2017 Non-Employee Directors' Equity Incentive Plan | Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	18,705,022			18,705,022
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period				2,285,702
2017 Equity Incentive Plan and 2017 Non-Employee Directors' Equity Incentive Plan | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units outstanding (in shares)	5,014,690			5,014,690
Common stock issued (in shares)				6,730,226
2017 Equity Incentive Plan and 2017 Non-Employee Directors' Equity Incentive Plan | Restricted Stock Award (RSAs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued (in shares)				217,148
2017 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options exercise price, percent of fair market value on date of grant	100.00%
Vesting period	4 years
Award term	10 years
Common stock authorized (in shares)	55,000,000			55,000,000
2017 Equity Incentive Plan | Restricted Stock Units (RSUs) | Share-Based Payment Arrangement, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	33.33%
2017 Equity Incentive Plan | Restricted Stock Units (RSUs) | Share-Based Payment Arrangement, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	33.33%
2017 Equity Incentive Plan | Restricted Stock Units (RSUs) | Share-Based Payment Arrangement, Tranche Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	33.33%
2017 Non-Employee Directors' Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award term	10 years
Common stock authorized (in shares)	2,000,000			2,000,000
2017 Non-Employee Directors' Equity Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate value	$ 500,000			$ 500,000
2017 Non-Employee Directors' Equity Incentive Plan | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year