CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Revenue	$ 34,288	$ 31,176	$ 15,353
Expenses:
Research and development	173,797	168,435	237,939
General and administrative	34,409	34,451	46,527
Total expenses	208,206	202,886	284,466
Loss from operations	(173,918)	(171,710)	(269,113)
Other income (expense):
Investment income	2,674	1,946	2,143
Interest expense	(13,612)	(14,072)	(12,965)
Other income (expense)	108	67	(31)
Net loss	$ (184,748)	$ (183,769)	$ (279,966)
Basic and diluted net loss per share	$ (0.50)	$ (0.63)	$ (1.03)
Basic and diluted weighted average number of common shares outstanding	369,757	292,669	270,802
Government contract [member]
Revenue:
Revenue	$ 0	$ 0	$ 2,184
Grant and other [Member]
Revenue:
Revenue	$ 34,288	$ 31,176	$ 13,169