Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 118,251	$ 157,480
Restricted cash	4,020	0
Marketable securities	160,134	46,508
Accounts receivable, net of allowance for doubtful accounts of $67 and $67, respectively	2,542	29,873
Other receivables	10,229	3,698
Prepaid expenses and other assets	10,839	7,574
Discontinued operations, current assets (Note 11)	0	5,555
Total current assets	306,015	250,688
Property and equipment, net of accumulated depreciation	4,534	385
Other assets	8,277	7,188
Facility and equipment under lease	3,842	0
Discontinued operations, non-current assets (Note 11)	0	132,625
Total assets	322,668	390,886
Current liabilities:
Accounts payable and other accrued liabilities	44,455	69,460
Accrued payroll and benefits	5,262	9,853
Contract liabilities	7,245	4,850
Discontinued operations, current liabilities (Note 11)	0	2,311
Total current liabilities	56,962	86,474
Deferred tax liabilities	0	1,469
Other long-term liabilities	10,923	5,650
Discontinued operations, non-current liabilities (Note 11)	0	14,031
Total liabilities	67,885	107,624
Commitments and contingencies (Note 9)
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; 112,684,387 and 110,525,141 issued and outstanding at June 30, 2019 and December 31, 2018, respectively	112	110
Additional paid-in capital	905,871	886,740
Accumulated other comprehensive loss	(3,764)	(3,702)
Accumulated deficit	(647,436)	(599,886)
Total stockholders’ equity	254,783	283,262
Total liabilities and stockholders’ equity	$ 322,668	$ 390,886