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 income (loss)	$ (24,794)	$ (27,614)	$ 11,256
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	679	952	1,110
Amortization of intangible assets	999	1,746	2,618
Stock-based compensation	3,698	3,811	3,766
Gain on sale of assets	(630)	(3,291)	(35,611)
Recovery of doubtful accounts			(125)
Other non-cash items	7		19
Changes in assets and liabilities, net of effects of acquisition:
Accounts receivable	139	682	235
Prepaid expenses and other assets	(314)	371	2,375
Deferred revenue	(311)	(439)	(881)
Accounts payable	(125)	(84)	(763)
Accrued expenses and other liabilities	(1,993)	1,850	305
Net cash used in operating activities	(22,645)	(22,016)	(15,696)
Cash flows from investing activities:
Purchases of property and equipment	(154)	(738)	(349)
Net cash paid for purchase of businesses			(1,500)
Net proceeds from sale of assets	630	3,437	34,831
Proceeds from sales and maturities of marketable securities	49,267	34,371	36,836
Purchases of marketable securities	(57,202)	(54,592)	(31,587)
Net cash (used in) provided by investing activities	(7,459)	(17,522)	38,231
Cash flows from financing activities:
Proceeds from the sale of common stock, net of issuance costs	27,746
Proceeds from issuance of common stock	4,193	3,636	3,336
Repurchase of common stock		(1,444)
Payments on capital lease obligations		(150)	(186)
Net cash provided by financing activities	31,939	2,042	3,150
Net increase (decrease) in cash and cash equivalents	1,835	(37,496)	25,685
Cash and cash equivalents at beginning of year	2,529	40,025	14,340
Cash and cash equivalents at end of year	4,364	2,529	40,025
Supplemental disclosure:
Cash paid for income taxes	92	345	53
Patent license recorded in connection with patent sale			$ 780