Summary of Significant Accounting Policies Equity Incentive Awards (Tables)

6 Months Ended

Jun. 30, 2021

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Abstract]

Schedule of Accrued Liabilities

Accrued liabilities: Accrued liabilities consisted of the following:

	As of June 30,		As of December 31,
	2021		2020
	(in thousands)
Accrued research and development services	$	6,869	$	21,962
Accrued compensation and benefits	3,544		6,200
Short term lease liability	1,027		553
Other	1,155		976
Total accrued liabilities	$	12,595	$	29,691

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Expected Volatility		Risk-free Interest Rate		Expected Term	Dividend Rate
June 30, 2021:
Employees	101	%	0.6	%	4	—	%
Officers and non-employee directors	90	%	1.1	%	7	—	%
June 30, 2020:
Employees	90	%	1.3	%	4	—	%
Officers and non-employee directors	78	%	1.4	%	8	—	%

Share-based Payment Arrangement, Option, Activity [Table Text Block]

	Options	Weighted Average Exercise Price
	(in thousands)
Outstanding at December 31, 2020	8,397	$	7.12
Granted	1,109	7.87
Exercised	(111)	5.01
Expired	(191)	12.50
Forfeited	(56)	8.52
Outstanding at June 30, 2021	9,148	7.12
Exercisable at June 30, 2021	5,527	$	8.36

Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]

	Shares	Weighted Average Grant Date Fair Value
	(in thousands)
Outstanding at December 31, 2020	2,769	$	4.35
Granted	663	8.22
Vested	(1,239)	5.04
Forfeited	(134)	5.16
Outstanding at June 30, 2021	2,059	$	5.13