CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)
$ in Thousands
Sep. 30, 2019
Dec. 31, 2018
Current assets:    
Cash and cash equivalents $ 109,611 $ 307,064
Investments 215,078 96,987
Prepaid expenses and other current assets 5,073 9,737
Restricted cash   622
Total current assets 329,762 414,410
Operating lease, right-of-use-asset 47,911  
Property, plant and equipment, net 52,478 62,796
Restricted cash 1,735 1,735
Other assets 386 168
Total assets 432,272 479,109
Current liabilities:    
Accounts payable 11,679 7,886
Accrued expenses and other current liabilities 14,866 7,616
Operating lease liabilities 6,998 4,502
Total current liabilities 33,543 20,004
Long-term debt, net of discount 49,509 24,347
Other long-term liabilities 438 309
Operating lease liabilities, net of current portion 41,439 41,441
Total liabilities 124,929 86,101
Commitments and contingencies (see Note 11)
Stockholders' equity:    
Preferred stock, $0.001 par value; 10,000,000 shares authorized at September 30, 2019 and December 31, 2018; no shares issued or outstanding at September 30, 2019 and December 31, 2018
Common stock, $0.001 par value; 150,000,000 shares authorized at September 30, 2019 and December 31, 2018; 79,777,733 and 79,234,853 shares issued and outstanding at September 30, 2019 and December 31, 2018, respectively 80 79
Additional paid-in capital 575,365 543,040
Accumulated other comprehensive income (loss) 166 (29)
Accumulated deficit (268,268) (150,082)
Total stockholders' equity 307,343 393,008
Total liabilities and stockholders' equity $ 432,272 $ 479,109