CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net loss	$ (6,548)	$ (10,061)	$ (10,518)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	3,160	3,907	4,650
Tax benefit (deficit) from stock-based compensation	6	29	8
Excess tax benefit related to stock-based compensation	(6)	(22)	(8)
Depreciation and amortization	1,606	637	717
Other	(87)	107	(77)
Changes in assets and liabilities:
Accounts receivable	(3,690)	(1,000)	(759)
Inventories	1,167	(4,281)	(275)
Other current assets and prepaid expenses	859	2,604	2,314
Other long-term assets	89	(486)	0
Accounts payable	(466)	1,277	215
Accrued liabilities	(177)	2,970	(2,646)
Deferred rent	(62)	45	(200)
Deferred revenue	1,915	(895)	(1,208)
Income tax liability	(66)	1	(272)
Net cash used in operating activities	(2,300)	(5,168)	(8,059)
Cash flows from investing activities:
Acquisition of property and equipment	(516)	(751)	(275)
Business acquisition	(5,091)	0	0
Disposal of property and equipment	0	36	0
Proceeds from sales of marketable and long-term investments	31,564	21,198	42,830
Proceeds from maturities of marketable investments	43,009	47,935	42,505
Purchase of marketable investments	(58,813)	(63,131)	(87,837)
Net cash provided by (used in) investing activities	10,153	5,287	(2,777)
Cash flows from financing activities:
Proceeds from exercise of stock options and employee stock purchase plan	1,667	1,360	518
Excess tax benefit related to stock-based compensation	6	22	8
Net cash provided by financing activities	1,673	1,382	526
Net increase (decrease) in cash and cash equivalents	9,526	1,501	(10,310)
Cash and cash equivalents at beginning of year	14,020	12,519	22,829
Cash and cash equivalents at end of year	23,546	14,020	12,519
Supplemental and non-cash disclosure of cash flow information:
Cash paid (received) for income taxes	$ 307	$ (1,345)	$ 272