CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 58,729	$ 78,297
Accounts receivable	3,584	4,500
Prepaid expenses and other current assets	1,411	2,105
Total current assets	63,724	84,902
Property, plant and equipment, net	59,671	61,257
Deferred engineering costs	110,626	110,499
Non-current restricted cash	3,443	3,440
Other non-current assets	32,806	32,897
Total assets	270,270	292,995
Current liabilities:
Accounts payable	25,247	23,573
Accounts payable due to related parties	450	910
Accrued and other liabilities	19,897	22,003
Borrowings	16,848	72,819
Total current liabilities	62,442	119,305
Borrowings	0	38,275
Other non-current liabilities	25,922	26,325
Total long-term liabilities	25,922	64,600
Stockholders’ equity:
Preferred stock, $0.01 par value, 100,000,000 authorized: 6,123,782 and 6,123,782 shares outstanding, respectively	61	61
Common stock, $0.01 par value, 800,000,000 authorized: 401,037,076 and 354,315,739 shares outstanding, respectively	3,779	3,309
Additional paid-in capital	1,021,373	922,042
Accumulated deficit	(843,307)	(816,322)
Total stockholders’ equity	181,906	109,090
Total liabilities and stockholders’ equity	$ 270,270	$ 292,995
Common stock, shares authorized (in shares)	800,000,000	800,000,000