CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net loss	$ (3,610)	$ (2,163)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	625	820
Depreciation and amortization	331	320
Other	97	34
Changes in assets and liabilities:
Accounts receivable	3,091	2,027
Inventories	(634)	23
Other current assets and prepaid expenses	(792)	60
Other long-term assets	303	35
Accounts payable	663	54
Accrued liabilities	(1,534)	(2,504)
Other long-term liabilities	(70)	(56)
Deferred revenue	548	584
Income tax liability	10	(92)
Net cash used in operating activities	(972)	(858)
Cash flows from investing activities:
Acquisition of property, equipment and software	(239)	(174)
Proceeds from sales of marketable investments	3,200	500
Proceeds from maturities of marketable investments	7,240	11,050
Purchase of marketable investments	(16,791)	(20,473)
Net cash used in investing activities	(6,590)	(9,097)
Cash flows from financing activities:
Proceeds from exercise of stock options and employee stock purchase plan	2,096	3,717
Payments on capital lease obligations	(33)	(36)
Net cash provided by financing activities	2,063	3,681
Net decrease in cash and cash equivalents	(5,499)	(6,274)
Cash and cash equivalents at beginning of period	16,242	14,020
Cash and cash equivalents at end of period	$ 10,743	$ 24,334