Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 234,954	$ 197,569
Short-term investments	1,000	52,086
Accounts receivable, net	1,961	0
Inventory	5,612	0
Prepaid expenses and other current assets	3,290	4,487
Total current assets	246,817	254,142
Property, plant and equipment, net	58,360	31,932
Other assets	4,017	4,202
Total assets	309,194	290,276
Current liabilities
Accounts payable	7,066	6,245
Accrued expenses and other current liabilities	27,948	18,939
Total current liabilities	35,014	25,184
Convertible notes, net	0	123,845
Other non-current liabilities	5,598	5,648
Total liabilities	40,612	154,677
Commitments and contingencies (Note 12)
Stockholders’ equity
Preferred stock, $0.001 par value; 15,000,000 shares authorized as of September 30, 2018 and December 31, 2017; None issued and outstanding	0	0
Common stock, $0.001 par value; 150,000,000 shares authorized as of September 30, 2018 and December 31, 2017; 45,451,227 and 36,947,637 shares issued and outstanding as of September 30, 2018 and December 31, 2017, respectively	45	37
Additional paid-in capital	913,499	597,318
Accumulated other comprehensive loss	(1)	(28)
Accumulated deficit	(644,961)	(461,728)
Total stockholders’ equity	268,582	135,599
Total liabilities and stockholders’ equity	$ 309,194	$ 290,276