Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of income taxes at the U.S. federal statutory rate to the provision for income taxes
Benefit at U.S. federal statutory rate	$ (15,451,000)	$ (65,289,000)	$ (11,146,000)
Unbenefitted net operating losses and tax credits	6,492,000	57,102,000	(1,451,000)
Non-deductible amortization of debt discount	8,347,000	7,612,000	6,937,000
Expiring capital loss carryforward			5,371,000
Other	786,000	575,000	289,000
Provision for income taxes	174,000
Deferred tax assets:
Federal and state net operating loss carryforwards	493,000,000	484,000,000
Federal and state research credits	96,000,000	91,000,000
Capitalized research and development	14,000,000	20,000,000
Deferred revenue and accruals	44,000,000	72,000,000
Non-cash compensation	22,000,000	17,000,000
Investments	6,000,000	6,000,000
Other, net	2,000,000	3,000,000
Total gross deferred tax assets	677,000,000	693,000,000
Less valuation allowance for deferred tax assets	(677,000,000)	(693,000,000)
Valuation allowance
Increase (decrease) in valuation allowance	$ (16,000,000)	$ 72,000,000	$ 11,000,000