CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (15,213)	$ (24,407)	$ (31,790)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	21,826	29,959	39,235
Operating lease cost	1,201
Non-cash compensation	1,206	1,368	976
Deferred income tax (benefit) expense	(23)	(757)	763
Change in other accrued long-term liabilities			(1,489)
(Gain) loss on disposal of assets	(86)	16	(1,714)
Remeasurement and other	(139)		(91)
Change in operating assets and liabilities:
Decrease (increase) in accounts receivable	1,118	6,744	(16,465)
Decrease (increase) in prepaid expenses and other current assets	6,983	(2,664)	278
(Decrease) increase in accounts payable	(579)	(798)	1,207
Increase (decrease) in accrued liabilities	1,356	(777)	1,458
Decrease in operating lease liabilities	(1,150)
(Decrease) increase in deferred revenue	(7,020)	4,187	929
Net cash provided by (used in) operating activities	9,480	12,871	(6,703)
Cash flows from investing activities:
Capital expenditures, net of non-cash capital expenditures summarized below	(4,396)	(15,745)	(8,675)
Proceeds from maturity of short-term investments	33,075	55,000	61,250
Acquisition of short-term investments	(24,842)	(49,000)	(37,583)
Proceeds from disposal of assets	297	437	1,325
Proceeds from flood insurance claims		687	375
Proceeds from notes receivable	51	25	96
Net cash provided by (used in) investing activities	4,185	(8,596)	16,788
Cash flows from financing activities:
Proceeds from notes payable		6,518
Principal payments on notes payable	(8,165)	(1,180)	(2,186)
Principal payments on finance leases	(2,855)	(2,699)	(1,076)
Tax withholdings related to stock-based compensation awards	(236)	(121)	(158)
Cash in lieu of stock dividend paid		(1)
Net cash (used in) provided by financing activities	(11,256)	2,517	(3,420)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	133	(76)	724
Net increase in cash, cash equivalents and restricted cash	2,542	6,716	7,389
Cash, cash equivalents and restricted cash at beginning of period	28,729	22,013	14,624
Cash, cash equivalents and restricted cash at end of period	31,271	28,729	22,013
Supplemental cash flow information:
Cash paid for interest	440	408	143
Cash paid for income taxes	40	14
Cash received for income taxes	55		4,791
Non-cash operating, investing and financing activities:
(Decrease) increase in accrued purchases of property and equipment	(927)	353	(907)
Finance leases incurred	121		8,542
Increase in right-of-use assets and operating lease liabilities	8,252
Decrease in right-of-use assets for accrued rent	(497)
Increase in right-of-use assets for prepaid rent	14
Financed insurance premiums	$ 2,256	$ 2,317	248
Equipment sales financed for buyer			(1,500)
Sales tax on equipment sales financed for buyer			$ (132)