Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (12,236)	$ (26,505)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	2,577	4,493
Depreciation and amortization expense	90	1,229
Change in fair value of warrant and private placement option liabilities	(7,506)	(14,256)
(Gain) loss on dispositions, net	478	(3,761)
Amortization of right-of-use assets	33	297
Accretion of lease liability	23	371
Amortization of deferred issuance costs	0	550
Changes in operating assets and liabilities:
Accounts receivable, interest and other receivables	(181)	178
Prepaid expenses and other assets	(216)	103
Accounts payable	(370)	(1,345)
Accrued liabilities and other	230	(4,629)
Net cash used in operating activities	(17,078)	(43,275)
Cash flows from investing activities:
Proceeds from sale of property and equipment, net	900	14,909
Purchases of property and equipment	(7)	(807)
Net cash provided by investing activities	893	14,102
Cash flows from financing activities:
Payment on debt	0	(10,000)
Proceeds from issuance of stock from employee stock purchase plan	0	65
Payment on financing lease obligations	(35)	(56)
Net cash used in financing activities	(35)	(9,991)
Effect of exchange rate changes on cash	(9)	(26)
Net change in cash, cash equivalents, and restricted cash	(16,229)	(39,190)
Cash, cash equivalents and restricted cash at beginning of period	36,996	93,816
Cash, cash equivalents and restricted cash at end of period	20,767	54,626
Supplemental cash flow information:
Cash paid during the period for interest	0	1,973
Non-cash investing and financing activities:
Purchases of property and equipment in accounts payables and accrued liabilities	0	859
Leasehold improvements paid by landlord	0	113
Conversion of redeemable preferred stock into common stock	0	160
Reclassification of property and equipment, net to assets held for sale	$ 0	$ 199