Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities:
Net income (loss)	$ 772	$ (1,441)
Reconciliation of net loss to net cash used in operating activities:
Depreciation and amortization	590	484
Stock-based compensation expense	566	341
Changes in operating assets and liabilities:
Accounts receivable	(3,799)	2,107
Inventories	8	(72)
Prepaid expenses and other current assets	1,145	48
Accounts payable	1,117	(1,363)
Accrued expenses and other	(1,675)	(1,039)
Deferred rent	(11)	(9)
Deferred revenue	186	806
Net cash used in operating activities	(1,101)	(138)
Investing activities:
Purchases of property and equipment	(875)	(520)
Net cash used in investing activities	(875)	(520)
Financing activities:
Proceeds from sale of common stock / exercise of options	1,387
Proceeds from equipment loans		1,501
Principal payments on debt	(138)	(79)
Payments to satisfy employee taxes due on vesting of restricted awards	(60)
Dividends paid		(7)
Net cash provided by financing activities	1,189	1,415
Effect of exchange rate changes on cash and cash equivalents	26	8
Net (decrease) increase in cash and cash equivalents	(761)	765
Cash and cash equivalents, beginning of period	21,446	20,994
Cash and cash equivalents, end of period	20,685	21,759
Supplemental cash flow information
Cash paid for interest	46	23
Supplemental noncash information
Purchases of equipment through accounts payable and accrued expenses	$ 98	$ 215