Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net loss	$ (5,533)	$ (6,351)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Stock-based compensation	1,943	1,318
Depreciation and amortization	622	660
Other	245	93
Changes in assets and liabilities:
Accounts receivable	2,218	2,079
Inventories	(2,533)	(1,024)
Other current assets and prepaid expenses	154	(99)
Other long-term assets	10	309
Accounts payable	514	208
Accrued liabilities	(686)	(1,885)
Other long-term liabilities	(145)	(141)
Deferred revenue	(1,478)	1,305
Income tax liability	35	36
Net cash used in operating activities	(4,634)	(3,492)
Cash flows from investing activities:
Acquisition of property, equipment and software	(678)	(283)
Proceeds from sales of marketable investments	7,379	4,681
Proceeds from maturities of marketable investments	21,350	19,165
Purchase of marketable investments	(12,262)	(27,850)
Net cash provided by (used in) investing activities	15,789	$ (4,287)
Cash flows from financing activities:
Repurchase of common stock	(17,744)
Proceeds from exercise of stock options and employee stock purchase plan	8,508	$ 2,511
Payments on capital lease obligations	(95)	(72)
Net cash provided by (used in) financing activities	(9,331)	2,439
Net increase (decrease) in cash and cash equivalents	1,824	(5,340)
Cash and cash equivalents at beginning of period	9,803	16,242
Cash and cash equivalents at end of period	$ 11,627	$ 10,902