Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities:
Net loss	$ (6,351)	$ (2,801)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Stock-based compensation	1,318	1,622
Depreciation and amortization	660	646
Other	93	50
Changes in assets and liabilities:
Accounts receivable	2,079	1,299
Inventories	(1,024)	596
Other current assets and prepaid expenses	(99)	242
Other long-term assets	309	49
Accounts payable	208	323
Accrued liabilities	(1,885)	(1,952)
Other long-term liabilities	(141)	(112)
Deferred revenue	1,305	1,117
Income tax liability	36	(87)
Net cash provided by (used in) operating activities	(3,492)	992
Cash flows from investing activities:
Acquisition of property, equipment and software	(283)	(306)
Proceeds from sales of marketable investments	4,681	4,975
Proceeds from maturities of marketable investments	19,165	16,200
Purchase of marketable investments	(27,850)	(37,243)
Net cash used in investing activities	(4,287)	(16,374)
Cash flows from financing activities:
Proceeds from exercise of stock options and employee stock purchase plan	2,511	3,781
Payments on capital lease obligations	(72)	(60)
Net cash provided by financing activities	2,439	3,721
Net decrease in cash and cash equivalents	(5,340)	(11,661)
Cash and cash equivalents at beginning of period	16,242	23,546
Cash and cash equivalents at end of period	$ 10,902	$ 11,885