Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities
Net income (loss)	$ 249	$ (10,458)
Adjustments to reconcile net income (loss) to net cash used in operating activities
Non-cash interest expense		121
Depreciation and amortization expense		1,219
Gain on sale of property and equipment		(574)
Gain on sale of in progress research and development	(2,139)
Amortization and accretion on marketable securities		(216)
Stock-based compensation expense	484	594
Loss on equity method investment		301
Changes in operating assets and liabilities:
Prepaid expenses and other assets	186	(183)
Accounts payable, accrued expenses and other	215	(4,456)
Net cash used in operating activities	(1,005)	(13,652)
Cash flows from investing activities
Proceeds on sale of property and equipment		615
Proceeds from sale of in progress research and development	2,450
Proceeds from maturities and sales of marketable securities		29,500
Net cash provided by investing activities	2,450	30,115
Net increase in cash, cash equivalents and restricted cash	1,445	16,463
Cash, cash equivalents and restricted cash, beginning of period	16,580	20,663
Cash, cash equivalents and restricted cash, end of period	$ 18,025	37,126
Supplemental disclosure of cash flows
Cash paid for income taxes		10
Cash paid for interest		$ 361