CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (10,161)	$ (13,287)
Adjustments to reconcile net loss to net cash flows used in operating activities:
Share-based compensation	7,304	7,783
Depreciation	2,467	2,928
Amortization of intangible assets	454	542
Amortization of deferred financing costs	833	1,441
Non-cash lease expenses	480	486
Accretion of asset retirement obligation	37	0
Loss on fixed asset disposal	236	1
Increase (decrease) in cash resulting from changes in:
Accounts receivable	(1,820)	2,230
Inventory	224	(1,460)
Prepaid expenses	2,254	3,819
Income taxes	(93)	(10,682)
Other assets	1,387	821
Accounts payable	2,794	3,236
Accrued compensation	2,790	(518)
Accrued expenses	(13,752)	(12,109)
Other liabilities	(514)	(609)
Net cash flows used in operating activities	(5,080)	(15,378)
Cash flows from investing activities:
Purchases of equipment	(2,346)	(1,421)
Principal payments from note receivable	45	0
Patent application costs	(200)	(151)
Net cash flows used in investing activities	(2,501)	(1,572)
Cash flows from financing activities:
Proceeds from exercise of stock options	1,359	298
Stock repurchased for tax withholdings on vesting of restricted stock	(4,563)	(2,330)
Principal payments on finance lease	(20)	0
Deferred financing cost	0	(23)
Repayment of term loans	0	(11,875)
Proceeds from term loans	0	10,000
Net cash flows used in financing activities	(3,224)	(3,930)
Net change in cash	(10,805)	(20,880)
Cash and cash equivalents, beginning of period	95,812	69,069
Cash and cash equivalents, end of period	$ 85,007	$ 48,189