Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 127,789	$ 30,915
Marketable securities	264,589	174,688
Accounts receivable, net	410
Inventories	1,799
Prepaid expenses and other current assets	3,403	3,790
Total current assets	397,990	209,393
Property and equipment, net	11,189	11,664
Long-term investments	31,538	4,725
Restricted cash	600	480
Total assets	441,317	226,262
Current liabilities:
Accounts payable	6,222	2,161
Accrued expenses and other current liabilities	14,383	6,245
Current portion of long-term debt	9,967	9,134
Total current liabilities	30,572	17,540
Long-term debt, net	12,936	21,399
2024 convertible notes, net	137,107
Other long-term liabilities	428	291
Total liabilities	181,043	39,230
Commitments and contingencies
Preferred Stock, $0.001 par value; 10,000,000 shares authorized at December 31, 2017 and December 31, 2016 and 0 shares issued and outstanding at December 31, 2017 and December 31, 2016	0	0
Stockholders’ equity:
Common stock, $0.001 par value; 100,000,000 shares authorized; 37,610,897 and 31,667,469 shares issued and outstanding, at December 31, 2017 and December 31, 2016, respectively	38	32
Additional paid-in capital	609,810	398,757
Accumulated other comprehensive loss	(407)	(71)
Accumulated deficit	(349,167)	(211,686)
Total stockholders’ equity	260,274	187,032
Total liabilities and stockholders’ equity	$ 441,317	$ 226,262