CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED) - USD ($) shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues:
Total revenues	$ 13,287,000	$ 8,584,000
Operating expenses:
Research and development	27,408,000	38,893,000
General and administrative	8,864,000	10,778,000
Restructuring charge	825,000	559,000
Total operating expenses	37,097,000	50,230,000
Loss from operations	(23,810,000)	(41,646,000)
Investment income, net	646,000	1,422,000
Non-cash interest expense on liability related to the sale of future royalties and convertible senior notes	(5,702,000)	(3,432,000)
Interest expense on convertible senior notes	(24,000)	(24,000)
Other expense, net	(198,000)	(71,000)
Net loss	$ (29,088,000)	$ (43,751,000)
Basic and diluted net loss per common share (in dollar per share)	$ (0.17)	$ (0.30)
Basic and diluted weighted average common shares outstanding (in shares)	166,947	147,813
Total comprehensive loss	$ (29,088,000)	$ (43,751,000)
License and milestone fees
Revenues:
Total revenues	283,000	79,000
Non-cash royalty revenue related to the sale of future royalties
Revenues:
Total revenues	12,997,000	8,488,000
Research and development support
Revenues:
Total revenues	$ 7,000	$ 17,000