Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 139,534	$ 197,945
Short-term investments	68,330	35,717
Prepaid expenses and other current assets	2,351	4,028
Total current assets	210,215	237,690
Property, plant and equipment, net	12,532	7,857
Other assets, net	2,661	2,707
Total assets	225,408	248,254
Current liabilities
Accounts payable and other current liabilities	13,023	18,820
Interest payable	539	551
Total current liabilities	13,562	19,371
Convertible notes, net of discounts	123,615	123,539
Other non-current liabilities	4,115	0
Total liabilities	141,292	142,910
Commitments and contingencies (Note 11)
Stockholders’ equity
Preferred stock, $0.001 par value; 15,000,000 shares authorized as of March 31, 2017 and December 31, 2016; None issued and outstanding	0	0
Common stock, $0.001 par value; 150,000,000 shares authorized as of March 31, 2017 and December 31, 2016; 33,634,673 and 33,458,607 shares issued and outstanding as of March 31, 2017 and December 31, 2016, respectively	34	33
Additional paid-in capital	426,597	422,002
Accumulated other comprehensive loss	(105)	(68)
Accumulated deficit	(342,410)	(316,623)
Total stockholders’ equity	84,116	105,344
Total liabilities and stockholders’ equity	$ 225,408	$ 248,254