Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 202,818	$ 197,569
Short-term investments	0	52,086
Accounts receivable, net	2,715	0
Inventory	10,112	0
Prepaid expenses and other current assets	4,530	4,487
Total current assets	220,175	254,142
Property, plant and equipment, net	60,525	31,932
Other assets	4,344	4,202
Total assets	285,044	290,276
Current liabilities
Accounts payable	12,403	6,245
Accrued expenses and other current liabilities	38,381	18,939
Total current liabilities	50,784	25,184
Convertible notes, net	0	123,845
Other non-current liabilities	6,454	5,648
Total liabilities	57,238	154,677
Commitments and contingencies (Note 13)
Stockholders’ equity
Preferred stock, $0.001 par value; 15,000,000 shares authorized as of December 31, 2018 and December 31, 2017; None issued and outstanding	0	0
Common stock, $0.001 par value; 150,000,000 shares authorized as of December 31, 2018 and December 31, 2017; 45,478,883 and 36,947,637 shares issued and outstanding as of December 31, 2018 and December 31, 2017, respectively	45	37
Additional paid-in capital	924,180	597,318
Accumulated other comprehensive loss	0	(28)
Accumulated deficit	(696,419)	(461,728)
Total stockholders’ equity	227,806	135,599
Total liabilities and stockholders’ equity	$ 285,044	$ 290,276