Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating activities:
Net loss	$ (6,158)	$ (9,682)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	1,073	1,115
Provision for doubtful accounts and other adjustments to accounts receivable	145	419
Provision for excess and obsolete inventory	35	19
Non-cash compensation related to stock options and restricted stock	905	1,178
Change in operating accounts:
Accounts receivable	(996)	(425)
Income tax receivable		352
Inventories	8	34
Prepaid expenses and other assets	171	357
Accounts payable and accrued liabilities	931	(1,477)
Net cash used in operating activities	(3,886)	(8,110)
Investing activities:
Capital expenditures	(90)	(55)
Proceeds from (purchase of) short-term investments	(2,167)	17,121
Net cash provided by (used in) investing activities	(2,257)	17,066
Financing activities:
Cash received from stock sale for employee stock purchase plan	21	55
Cash received from exercise of stock options		10
Repurchase of common stock		(329)
Net cash provided by (used in) financing activities	21	(264)
Net increase (decrease) in cash and cash equivalents	(6,122)	8,692
Cash and cash equivalents, beginning of period	18,873	7,475
Cash and cash equivalents, end of period	12,751	16,167
Supplemental disclosures of cash flow information:
Cash paid for income taxes	$ 71	$ 91