CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
REVENUE:
Product Development and Licensing Agreements	$ 556	$ 453
Contracts and Grants	978	850
Total Revenue	1,534	1,303
OPERATING EXPENSE:
Research and Development	25,793	27,447
General and Administrative	7,229	9,307
Loss on Fair Value Remeasurement of Contingent Consideration	3,400
Amortization of Acquired Intangible Assets	224	253
Total Operating Expense	36,646	37,007
Operating Loss	(35,112)	(35,704)
Investment and Other Income, Net	851	1,031
Net Loss	$ (34,261)	$ (34,673)
Basic and Diluted Net Loss Per Common Share (in dollars per share)	$ (0.28)	$ (0.35)
Shares Used in Calculating Basic and Diluted Net Loss per Share (in shares)	122,648	98,689
COMPREHENSIVE LOSS:
Net Loss	$ (34,261)	$ (34,673)
Other Comprehensive Income:
Unrealized Gain on Marketable Securities	21	380
Comprehensive Loss	$ (34,240)	$ (34,293)