Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenues	$ 0	$ 0	$ 0	$ 0
Operating costs and expenses:
Selling, general and administrative	15,116	13,126	44,654	46,308
Research and development	24,453	17,167	62,192	56,035
Total operating costs and expenses	39,569	30,293	106,846	102,343
Loss from continuing operations before other income (expense) and income taxes	(39,569)	(30,293)	(106,846)	(102,343)
Other income (expense):
Interest income, net	188	1,521	1,217	4,076
Other income (expense), net	(9,131)	2,015	(15,720)	(5,547)
Total other income (expense)	(8,943)	3,536	(14,503)	(1,471)
Loss from continuing operations before income taxes	(48,512)	(26,757)	(121,349)	(103,814)
(Provision) benefit for income taxes from continuing operations	(6)	200	(15)	8,628
Loss from continuing operations	(48,518)	(26,557)	(121,364)	(95,186)
Income from discontinued operations, net of income taxes	66	572	255	21,547
Net loss	$ (48,452)	$ (25,985)	$ (121,109)	$ (73,639)
Basic and diluted loss per share:
Loss per common share from continuing operations ($ per share)	$ (0.37)	$ (0.24)	$ (1.02)	$ (0.86)
Income per common share from discontinued operations ($ per share)	0.00	0.01	0.00	0.20
Net loss per common share ($ per share)	$ (0.37)	$ (0.23)	$ (1.02)	$ (0.67)
Weighted average shares outstanding, basic and diluted	131,455,727	111,178,880	118,664,914	110,291,090