Summary of Significant Accounting Policies Equity Incentive Awards (Tables)

3 Months Ended

Mar. 31, 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 March 31,		As of December 31,
	2021		2020
	(in thousands)
Accrued research and development services	$	16,505	$	21,962
Accrued compensation and benefits	3,552		6,200
Short term lease liability	1,026		553
Other	1,326		976
Accrued liabilities	$	22,409	$	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
March 31, 2021:
Employees	105	%	0.4	%	4	—	%
Officers and non-employee directors	90	%	1.0	%	7	—	%
March 31, 2020:
Employees	89	%	1.3	%	4	—	%
Officers and non-employee directors	77	%	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	957	8.37
Exercised	(109)	5.03
Expired	(178)	12.55
Forfeited	(31)	10.12
Outstanding at March 31, 2021	9,036	7.16
Exercisable at March 31, 2021	5,183	$	8.63

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	631	8.38
Vested	(1,154)	5.27
Forfeited	(33)	4.67
Outstanding at March 31, 2021	2,213	$	5.02