Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 70,352	$ 64,418
Marketable securities	107,441	159,455
Accounts receivable, net of allowance for credit losses of $43 and $43, respectively	435	441
Other receivables	8,789	9,558
Prepaid expenses and other assets	10,263	10,148
Total current assets	197,280	244,020
Property and equipment, net of accumulated depreciation	12,058	11,607
Other assets	3,187	4,000
Facility and equipment under lease	3,467	3,806
Total assets	215,992	263,433
Current liabilities:
Accounts payable and other accrued liabilities	49,130	54,284
Accrued payroll and benefits	4,568	7,686
Total current liabilities	53,698	61,970
Other long-term liabilities	8,526	11,070
Total liabilities	62,224	73,040
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.001 par value; 300,000,000 shares authorized; 114,774,079 and 113,299,612 issued and outstanding at March 31, 2020 and December 31, 2019, respectively	114	113
Additional paid-in capital	923,480	918,205
Accumulated other comprehensive loss	(4,827)	(3,498)
Accumulated deficit	(764,999)	(724,427)
Total stockholders’ equity	153,768	190,393
Total liabilities and stockholders’ equity	$ 215,992	$ 263,433