Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 148,868	$ 202,818
Accounts receivable, net	14,758	2,715
Inventory	10,192	10,112
Prepaid expenses and other current assets	6,499	4,530
Total current assets	180,317	220,175
Property, plant and equipment, net	62,982	60,525
Operating lease right-of-use assets	16,394	0
Other assets	3,357	4,344
Total assets	263,050	285,044
Current liabilities
Accounts payable	11,121	12,403
Accrued expenses and other current liabilities	35,810	38,381
Operating lease liabilities	5,032	0
Total current liabilities	51,963	50,784
Long-term operating lease liabilities	12,044	0
Other non-current liabilities	6,893	6,454
Total liabilities	70,900	57,238
Commitments and contingencies (Note 11)
Stockholders’ equity
Preferred stock, $0.001 par value; 15,000,000 shares authorized as of March 31, 2019 and December 31, 2018; None issued and outstanding	0	0
Common stock, $0.001 par value; 150,000,000 shares authorized as of March 31, 2019 and December 31, 2018; 45,921,976 and 45,478,883 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	46	45
Additional paid-in capital	936,474	924,180
Accumulated deficit	(744,370)	(696,419)
Total stockholders’ equity	192,150	227,806
Total liabilities and stockholders’ equity	$ 263,050	$ 285,044