Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Collaboration revenue	$ 1,069	$ 0	$ 1,069	$ 0
Operating expenses:
Research and development	27,096	26,741	51,448	49,721
Selling, general and administrative	15,459	8,577	26,377	16,647
Change in fair value of contingent purchase consideration	(700)	(2,500)	2,300	(2,500)
Total operating expenses	41,855	32,818	80,125	63,868
Loss from operations	(40,786)	(32,818)	(79,056)	(63,868)
Other income (expense):
Interest income	2,983	1,029	6,139	1,862
Other income (expense)	40	2,950	(48)	2,987
Total other income (expense)	3,023	3,979	6,091	4,849
Net loss from continuing operations	(37,763)	(28,839)	(72,965)	(59,019)
Loss from discontinued operations, net of taxes	0	(198)	0	(198)
Net loss	$ (37,763)	$ (29,037)	$ (72,965)	$ (59,217)
Net loss per share, basic and diluted:
Continuing operations (in dollars per share)	$ (0.89)	$ (0.82)	$ (1.72)	$ (1.68)
Discontinued operations (in dollars per share)	0	(0.01)	0	(0.01)
Net loss per share, basic and diluted (in dollars per share)	$ (0.89)	$ (0.83)	$ (1.72)	$ (1.69)
Weighted average common shares used in the calculation of basic and diluted net loss per common share (shares)	42,458	35,355	42,348	35,099