Income Taxes (Tables)

12 Months Ended

Dec. 31, 2012

Income Taxes

Schedule of reconciliation of income taxes at the U.S. federal statutory rate to the provision for income taxes

	Year Ended December 31,
	2012			2011			2010
Benefit at U.S. federal statutory rate	$	(15,451	)	$	(65,289	)	$	(11,146	)
Unbenefitted net operating losses and tax credits		6,492			57,102			(1,451	)
Non-deductible amortization of debt discount		8,347			7,612			6,937
Expiring capital loss carryforward		—			—			5,371
Other		786			575			289
Provision for income taxes	$	174		$	—		$	—

Schedule of significant components of deferred tax assets

	December 31,
	2012			2011
Deferred tax assets:
Federal and state net operating loss carryforwards	$	493,000		$	484,000
Federal and state research credits		96,000			91,000
Capitalized research and development		14,000			20,000
Deferred revenue and accruals		44,000			72,000
Non-cash compensation		22,000			17,000
Investments		6,000			6,000
Other, net		2,000			3,000
Total gross deferred tax assets		677,000			693,000
Less valuation allowance for deferred tax assets		(677,000	)		(693,000	)
Net deferred tax assets	$	—		$	—