Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities:
Net income (loss)	$ 5,951	$ (1,496)	$ 4,656
Reconciliation of net income to net cash provided by (used in) operating activities:
Depreciation and amortization	1,899	1,911	1,992
Change in fair value of common stock warrants	0	0	(379)
Share-based compensation expense	1,201	1,750	607
Deferred income taxes			542
Changes in operating assets and liabilities:
Accounts receivable	192	(2,499)	1,705
Due from related party			900
Inventories	(1,998)	(424)	(619)
Prepaid expenses and other current assets	64	259	(331)
Other non-current assets	18	(89)	(5)
Accounts payable	1,585	(925)	91
Accrued expenses	1,214	1,591	(896)
Deferred revenue	1,033	(1,038)	(1,334)
Deferred rent	27	69
Net cash provided by (used in) operating activities	11,186	(891)	6,929
Investing activities:
Purchase of property and equipment	(3,564)	(1,708)	(2,048)
Net cash used in investing activities	(3,564)	(1,708)	(2,048)
Financing activities:
Proceeds from exercise of stock options		82	33
Principal payments on notes payable	(226)	(238)	(245)
Payments for the purchase of treasury stock		(22)	(8,509)
Dividends paid	(28)	(28)	(28)
Net cash used in financing activities	(254)	(206)	(8,749)
Effect of exchange rate changes on cash and cash equivalents	(275)	(56)	(85)
Net increase (decrease) in cash and cash equivalents	7,093	(2,861)	(3,953)
Cash and cash equivalents, beginning of period	13,901	16,762	20,715
Cash and cash equivalents, end of period	20,994	13,901	16,762
Supplemental cash flow information
Cash paid for interest	85	101	120
Cash paid for income taxes		2	$ 3
Supplemental noncash investing
Purchases of equipment through accounts payable and accrued expenses	$ 460	$ 95