Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income (loss)	$ 56,201	$ (2,027)	$ (6,515)
Adjustments to reconcile net income (loss) to cash provided by (used in) operating activities:
Income tax benefit	(46,982)
Share-based compensation expense	7,948	6,470	4,927
Depreciation and amortization	2,627	2,557	2,724
Non-cash interest expense	504	405	268
Increase in inventory reserve	511	325	592
Loss (gain) on sale or disposal of assets	22		(12,500)
Other	20	12	(7)
Changes in operating assets and liabilities:
Accounts receivable	(7,128)	(16,095)	(7,099)
Inventories	(2,728)	(4,975)	(2,667)
Contract assets	53	(2,793)	(4,937)
Prepaid expenses and other current assets	(1,460)	(655)	(324)
Other assets	(221)	(371)
Accounts payable	2,594	926	5,164
Accrued expenses and other liabilities	7,157	4,888	5,029
Deferred revenue	2,202	718	(1,977)
Net cash provided by (used in) operating activities	21,320	(10,615)	(17,322)
Cash flows from investing activities:
Proceeds from maturities of investment securities	22,500		5,000
Purchases of investment securities		(22,645)
Purchases of property and equipment	(9,615)	(2,350)	(854)
Proceeds from sale of assets	282	5,000	7,500
Purchase of intangibles	(5,000)		(40)
Net cash provided by (used in) investing activities	8,167	(19,995)	11,606
Cash flows from financing activities:
Proceeds from issuance of long-term debt		15,000
Payment of debt issuance costs		(136)
Proceeds from issuance of common stock, net		7,781	7,114
Proceeds from exercise of stock options	1,814	4,405	474
Taxes paid related to net share settlement of equity awards	(1,367)	(1,131)	(543)
Net cash provided by financing activities	447	25,919	7,045
Effect of exchange rate changes on cash	2		1
Net increase (decrease) in cash and cash equivalents	29,936	(4,691)	1,330
Cash and cash equivalents:
Beginning of year	23,201	27,892	26,562
End of year	53,137	23,201	27,892
Supplemental disclosure of cash flow information:
Cash paid for interest	3,538	3,025	2,353
Supplemental disclosure of non-cash investing activities:
Purchase of intangible assets included in accrued liabilities	2,500
Purchases of property and equipment included in accounts payable and accrued liabilities	$ 2,017	$ 970	49
Gain on sales of assets recognized in excess of cash received			$ 5,000