Condensed Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash Flows from Operating Activities:
Net loss	$ (15,442)	$ (18,616)
Adjustments to reconcile net loss to net cash used in operating activities:
Loss from disposition of assets	4	1
Non-employee stock option expense	2	1
Stock-based compensation	1,628	2,094
Decrease in fair value of warrant liability	(106)
Issuance of common stock for services rendered	1	38
Amortization of investment premiums		59
Depreciation expense	201	373
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	111	424
Accounts payable, accrued expenses, and other liabilities	(2,194)	16
Net cash used in operating activities	(15,795)	(15,610)
Cash Flows from Investing Activities:
Purchases of available-for-sale securities		(1,025)
Proceeds from maturity of available-for-sale securities		17,585
Decrease in restricted cash		102
Purchases of property and equipment		(21)
Net cash provided by investing activities		16,641
Cash Flows from Financing Activities:
Dividends paid	(423)
Proceeds from employee stock purchases	3	47
Payments on capital lease	(4)	(8)
Net cash (used in) provided by financing activities	(424)	39
Net (decrease) increase in cash and cash equivalents	(16,219)	1,070
Cash and cash equivalents, beginning of period	24,571	17,008
Cash and cash equivalents, end of period	$ 8,352	$ 18,078