CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Total revenues	$ 7,418	$ 3,573	$ 9,538
Operating expenses:
Research and development	42,534	42,672	66,449
General and administrative	14,456	15,426	19,269
Goodwill impairment			90,976
Intangible asset impairment	18,000		18,677
Other asset impairment		1,800
Gain on fair value remeasurement of contingent consideration	(4,218)	(1,294)	(29,621)
Amortization of acquired intangible assets	0	0	224
Total operating expenses	70,772	58,604	165,974
Operating loss	(63,354)	(55,031)	(156,436)
Investment and other income, net	2,407	4,153	4,487
Net loss before income tax benefit	(60,947)	(50,878)	(151,949)
Income tax benefit	1,167		765
Net loss	$ (59,780)	$ (50,878)	$ (151,184)
Basic and diluted net loss per common share	$ (2.02)	$ (3.51)	$ (14.48)
Shares used in calculating basic and diluted net loss per share	29,640	14,507	10,442
Comprehensive loss:
Net loss	$ (59,780)	$ (50,878)	$ (151,184)
Other comprehensive income (loss):
Unrealized (loss) gain on marketable securities	(30)	36	19
Comprehensive loss	(59,810)	(50,842)	(151,165)
Product development and licensing agreements
Revenues:
Total revenues	2,301	473	3,341
Contracts and grants
Revenues:
Total revenues	$ 5,117	$ 3,100	$ 6,197