Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 56,088	$ 118,564
Restricted cash	55	55
Marketable securities	179,453	134,714
Accounts receivable, net	8,048	4,441
Inventory	5,438	4,366
Prepaid expenses	6,429	5,175
Other current assets	2,241	2,191
Total current assets	257,752	269,506
Investments	131,750	176,978
Property and equipment, net	5,762	6,195
Intangible assets	7,981	8,180
Other assets	756	799
Total assets	404,001	461,658
Current liabilities:
Accounts payable	4,525	3,915
Accrued expenses and other current liabilities	34,849	49,512
Total current liabilities	39,374	53,427
Other non-current liabilities	165	189
Notes payable	169,284	166,006
Total liabilities	208,823	219,622
Commitments and contingencies
Stockholders’ equity:
Common stock, $.0001 par value; 200,000,000 shares authorized, 45,214,387 shares and 44,616,586 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively	5	4
Additional paid-in-capital	1,140,495	1,124,630
Accumulated other comprehensive loss	(1,483)	(314)
Accumulated deficit	(943,839)	(882,284)
Total stockholders’ equity	195,178	242,036
Total liabilities and stockholders’ equity	$ 404,001	$ 461,658