Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net income (loss)	$ (914)	$ (19,888)
Adjustments to reconcile net loss to net cash used in operating activities
Non-cash interest expense		141
Loss on extinguishment of debt		971
Depreciation and amortization expense		2,228
Gain on sale of equipment		(1,984)
Gain on sale of in progress research and development	(2,139)
Amortization and accretion on marketable securities		(279)
Stock-based compensation expense	948	1,081
Gain on equity method investment		(372)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(444)	2,432
Accounts payable, accrued expenses and other	(435)	(9,855)
Net cash used in operating activities	(2,984)	(25,525)
Cash flows from investing activities
Proceeds from sale of property and equipment		2,025
Proceeds from sale of in progress research and development	2,139
Proceeds from sale of equity method investment		7,800
Proceeds from maturities and sales of marketable securities		48,500
Net cash provided by investing activities	2,139	58,325
Cash flows from financing activities
Proceeds from exercise of stock options		23
Repayment of debt		(15,000)
Payment of debt extinguishment costs		(985)
Net cash used in financing activities		(15,962)
Net (decrease) increase in cash, cash equivalents and restricted cash	(845)	16,838
Cash, cash equivalents and restricted cash, beginning of period	16,580	20,663
Cash, cash equivalents and restricted cash, end of period	$ 15,735	37,501
Supplemental disclosure of cash flows
Cash paid for interest		$ 1,399