Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 64,418	$ 157,480
Marketable securities	159,455	46,508
Accounts receivable, net of allowance for doubtful accounts of $43 and $67, respectively	441	29,873
Other receivables	9,558	3,698
Prepaid expenses and other assets	10,148	7,574
Discontinued operations, current assets (Note 12)	0	5,555
Total current assets	244,020	250,688
Property and equipment, net of accumulated depreciation	11,607	385
Other assets	4,000	7,188
Facility and equipment under lease	3,806
Discontinued operations, non-current assets	0	132,625
Total assets	263,433	390,886
Current liabilities:
Accounts payable and other accrued liabilities	54,284	81,312
Accrued payroll and benefits	7,686	9,853
Contract liabilities	0	4,850
Discontinued operations, current liabilities (Note 12)	0	2,311
Total current liabilities	61,970	98,326
Deferred tax liabilities, net	0	1,469
Other long-term liabilities	11,070	5,650
Discontinued operations, non-current liabilities	0	14,031
Total liabilities	73,040	119,476
Commitments and contingencies (Note 10)
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; 113,299,612 and 110,525,141 issued and outstanding at December 31, 2019 and 2018, respectively	113	110
Additional paid-in capital	918,205	886,740
Accumulated other comprehensive loss	(3,498)	(3,702)
Accumulated deficit	(724,427)	(611,738)
Total stockholders’ equity	190,393	271,410
Total liabilities and stockholders’ equity	$ 263,433	$ 390,886