CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net loss	$ (4,747)	$ (6,548)	$ (10,061)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	3,110	3,160	3,907
Tax benefit (deficit) from stock-based compensation	0	6	29
Excess tax benefit related to stock-based compensation	0	(6)	(22)
Depreciation and amortization	1,304	1,606	637
Other	243	(87)	107
Changes in assets and liabilities:
Accounts receivable	(857)	(3,690)	(1,000)
Inventories	2,108	1,167	(4,281)
Other current assets and prepaid expenses	345	859	2,604
Other long-term assets	73	89	(486)
Accounts payable	(287)	(466)	1,277
Accrued liabilities	(371)	(177)	2,970
Other long-term liabilities	(218)	(62)	45
Deferred revenue	3,114	1,915	(895)
Income tax liability	(304)	(66)	1
Net cash provided by (used in) operating activities	3,513	(2,300)	(5,168)
Cash flows from investing activities:
Acquisition of property, equipment and software	(517)	(516)	(751)
Acquisition of intangible asset	(155)	0	0
Business acquisition	0	(5,091)	0
Disposal of property and equipment	63	0	36
Proceeds from sales of marketable and long-term investments	15,578	31,564	21,198
Proceeds from maturities of marketable investments	36,030	43,009	47,935
Purchase of marketable investments	(56,847)	(58,813)	(63,131)
Net cash (used in) provided by investing activities	(5,848)	10,153	5,287
Cash flows from financing activities:
Repurchase of common stock	(10,031)	0	0
Proceeds from exercise of stock options and employee stock purchase plan	5,189	1,667	1,360
Payments on capital lease obligation	(127)	0	0
Excess tax benefit related to stock-based compensation	0	6	22
Net cash provided by financing activities	(4,969)	1,673	1,382
Net (decrease) increase in cash and cash equivalents	(7,304)	9,526	1,501
Cash and cash equivalents at beginning of year	23,546	14,020	12,519
Cash and cash equivalents at end of year	16,242	23,546	14,020
Supplemental cash flow information:
Cash paid for interest	19	0	0
Cash paid (received) for income taxes	337	307	(1,345)
Supplemental non-cash investing and financing activites:
Assets acquired under capital lease	$ 577	$ 0	$ 0