CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating activities
Net loss	$ (5,937)	$ (3,260)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization expense	126	502
Stock-based compensation	823	959
Gain on reduction of lease liability	0	1,317
Other	105	139
Change in operating assets and liabilities:
Contracts and other receivables	466	(2,766)
Prepaid materials	0	368
Prepaid expenses and other assets	313	532
Accounts payable	(291)	936
Accrued liabilities	(57)	120
Accrued compensation	(1,144)	314
Contract liabilities	(6)	(2,518)
Other liabilities	(400)	(1,076)
Net cash used in operating activities	(6,002)	(4,433)
Investing activities
Sales of property and equipment	0	161
Net cash provided by investing activities	0	161
Financing activities
Proceeds from issuance of common stock, net	1	2,086
Principal payments on term loan	0	(1,364)
Payments on financing leases	(68)	(65)
Net cash (used in) provided by financing activities	(67)	657
Net decrease in cash and cash equivalents	(6,069)	(3,615)
Cash and cash equivalents at beginning of period	34,121	13,935
Cash and cash equivalents at end of period	28,052	10,320
Supplemental disclosure of cash flow information
Interest paid	$ (384)	$ (437)