CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues:
Total revenues	$ 15,542,000	$ 9,287,000	$ 24,126,000	$ 29,102,000
Operating expenses:
Research and development	28,559,000	38,701,000	67,452,000	83,532,000
General and administrative	8,700,000	8,652,000	19,478,000	18,647,000
Restructuring charge	19,342,000	686,000	19,901,000	2,417,000
Total operating expenses	56,601,000	48,039,000	106,831,000	104,596,000
Loss from operations	(41,059,000)	(38,752,000)	(82,705,000)	(75,494,000)
Investment income, net	1,287,000	814,000	2,709,000	1,476,000
Non-cash interest expense on liability related to the sale of future royalties and convertible senior notes	(3,818,000)	(2,611,000)	(7,250,000)	(5,657,000)
Interest expense on convertible senior notes	(23,000)	(23,000)	(47,000)	(47,000)
Other income (expense), net	167,000	(1,052,000)	96,000	(515,000)
Net loss	$ (43,446,000)	$ (41,624,000)	$ (87,197,000)	$ (80,237,000)
Basic and diluted net loss per common share (in dollar per share)	$ (0.29)	$ (0.31)	$ (0.59)	$ (0.61)
Basic and diluted weighted average common shares outstanding (in shares)	148,129	134,384	147,972	132,512
Total comprehensive loss	$ (43,446,000)	$ (41,624,000)	$ (87,197,000)	$ (80,237,000)
License and milestone fees
Revenues:
Total revenues	5,079,000	1,321,000	5,158,000	12,861,000
Non-cash royalty revenue related to the sale of future royalties
Revenues:
Total revenues	10,412,000	7,242,000	18,900,000	14,432,000
Research and development support
Revenues:
Total revenues	$ 51,000	388,000	$ 68,000	771,000
Clinical materials revenue
Revenues:
Total revenues		$ 336,000		$ 1,038,000