Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 109,363	$ 202,818
Accounts receivable, net	25,650	2,715
Inventory	10,419	10,112
Prepaid expenses and other current assets	8,678	4,530
Total current assets	154,110	220,175
Property, plant and equipment, net	58,595	60,525
Operating lease right-of-use assets	17,882	0
Other assets	3,554	4,344
Total assets	234,141	285,044
Current liabilities
Accounts payable	9,098	12,403
Accrued expenses and other current liabilities	46,523	38,381
Operating lease liabilities	5,494	0
Total current liabilities	61,115	50,784
Long-term operating lease liabilities	13,238	0
Other non-current liabilities	4,030	6,454
Total liabilities	78,383	57,238
Commitments and contingencies (Note 11)
Stockholders’ equity
Preferred stock, $0.001 par value; 15,000,000 shares authorized as of June 30, 2019 and December 31, 2018; None issued and outstanding	0	0
Common stock, $0.001 par value; 150,000,000 shares authorized as of June 30, 2019 and December 31, 2018; 45,949,418 and 45,478,883 shares issued and outstanding as of June 30, 2019 and December 31, 2018, respectively	46	45
Additional paid-in capital	947,246	924,180
Accumulated deficit	(791,534)	(696,419)
Total stockholders’ equity	155,758	227,806
Total liabilities and stockholders’ equity	$ 234,141	$ 285,044