Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Cash flows from operating activities
Net loss	$ (6,218)		$ (5,833)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	30		189
Stock-based compensation	413		375
Amortization of investment premium/discount	(79)		151
Other	(9)
Changes in operating assets and liabilities:
Prepaid expenses, receivables and other current assets	438		(113)
Other assets	4		26
Accounts payable	(926)		(602)
Accrued expenses	1,189		1,026
Deferred revenue	(72)		(303)
Other long-term liabilities			(23)
Net cash used in operating activities	(5,230)		(5,107)
Cash flows from investing activities
Purchases of investment securities	(4,050)		(24,347)
Maturities of investment securities	7,918		15,612
Proceeds from sales of property and equipment	9
Net cash provided by (used in) investing activities	3,877		(8,735)
Cash flows from financing activities
Proceeds from issuance of common stock and warrants, net of issuance costs	31		13,853
Repayments of long-term debt	(9)		(43)
Net cash provided by financing activities	22		13,810
Effect of exchange rate changes on cash			12
Net decrease in cash and cash equivalents	(1,331)		(20)
Cash and cash equivalents
Beginning of period	6,889	[1]	6,849
End of period	$ 5,558		$ 6,829

[1] The condensed consolidated balance sheet at December 31, 2011 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.