Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net loss	$ (25,618)	$ (51,464)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	2,887	4,132
Depreciation and amortization expense	925	3,742
Change in fair value of warrant and private placement option liabilities	(2,125)	0
Gain on dispositions, net	(3,761)	0
Amortization of discount on investment securities, net	0	(28)
Amortization of right-of-use assets	173	636
Accretion of lease liability	(535)	355
Amortization of deferred issuance costs	388	439
Changes in operating assets and liabilities:
Accounts receivable, interest and other receivables	176	372
Prepaid expenses and other assets	(160)	(2,336)
Accounts payable	(157)	(1,735)
Accrued liabilities and other	(2,662)	1,747
Deferred revenue	0	(1,907)
Net cash used in operating activities	(30,469)	(46,047)
Cash flows from investing activities:
Proceeds from sale of investment securities	0	35,679
Proceeds from sale of property and equipment, net	14,909	0
Purchases of property and equipment	(229)	(551)
Net cash provided by investing activities	14,680	35,128
Cash flows from financing activities:
Payment on debt	(10,000)	0
Proceeds from issuance of common stock in a public offering, net	0	8,977
Proceeds from issuance of stock from employee stock purchase plan	65	71
Proceeds from exercise of stock options	0	76
Payment on financing lease obligations	(35)	(14)
Net cash (used in) provided by financing activities	(9,970)	9,110
Effect of exchange rate changes on cash	(62)	(18)
Net change in cash, cash equivalents, and restricted cash	(25,821)	(1,827)
Cash, cash equivalents and restricted cash at beginning of period	93,816	48,668
Cash, cash equivalents and restricted cash at end of period	67,995	46,841
Supplemental cash flow information:
Cash paid during the period for interest	1,413	1,722
Non-cash investing and financing activities:
Purchases of property and equipment in accounts payables and accrued liabilities	60	0
Conversion of redeemable preferred stock into common stock	160	0
Reclassification of property and equipment, net to assets held for sale	$ 199	$ 0