CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating activities:
Net loss	$ (17,846)	$ (21,914)
Non-cash adjustments reconciling net loss to operating cash flows:
Depreciation	45	58
Amortization of premium on investments	(71)	14
Share-based compensation expense	1,766	3,038
Changes in operating assets and liabilities:
Other current assets	704	843
Other long-term assets	(710)	0
Accounts payable, accrued liabilities and other long-term liabilities	(3,540)	1,009
Cash flows used for operating activities	(18,232)	(16,952)
Investing activities:
Purchases of short-term investments	(63,310)	(21,797)
Disposal and maturities of short-term investments	22,100	21,530
Purchases of property and equipment	0	(45)
Cash flows used in investing activities	(41,210)	(312)
Financing activities:
Proceeds from sale of common stock, net	66,816	0
Proceeds from exercise of common stock options and warrants	0	2,326
Cash flows provided by financing activities	66,816	2,326
Increase (decrease) in cash and cash equivalents	7,374	(14,938)
Cash and cash equivalents, beginning of period	22,383	49,493
Cash and cash equivalents, end of period	29,757	34,555
Supplemental disclosures of non-cash investing activities:
Fixed asset additions included within accounts payable	$ 54	$ 0