Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of income tax benefit to Federal statutory rates [Abstract]
Income tax benefit, statutory rates	$ 12,687,000	$ 7,128,000	$ 6,519,000
State taxes on income, net of Federal benefit	2,288,000	1,633,000	1,206,000
Research and development tax credit	332,000	662,000	656,000
Employee Related	(988,000)	(1,758,000)	(4,746,000)
Warrant Valuation Related	189,000	1,210,000	2,184,000
Other	0	0	18,000
Income Tax Benefit	14,508,000	8,875,000	5,837,000
Valuation allowance	(14,508,000)	(8,875,000)	(5,837,000)
Income tax benefit	0	0	0
Long-term deferred tax assets [Abstract]
Net operating loss carryforwards(Federal and state)	160,522,000	147,045,000
Research and development tax credits	9,412,000	9,080,000
Compensation expense on stock	3,154,000	3,535,000
Charitable contribution carryforward	7,000	7,000
Other accrued	524,000	608,000
Depreciation	2,665,000	2,682,000
Capitalized research and development	1,516,000	1,740,000
Total long-term deferred tax assets	177,800,000	164,697,000
Long-term deferred tax liabilities	0	0
Net deferred tax assets	177,800,000	164,697,000
Less: valuation allowance	(177,800,000)	(164,697,000)
Deferred tax assets, net of valuation allowance	0	0
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits income tax penalties and interest accrued	0	0
Unrecognized tax benefits income tax penalties and interest expense	0	0	0
Research Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward amount	9,400,000	9,100,000
Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration dates	expire in 2008 and will continue through 2032
Amount of operating loss carryforwards expire before 2014	6,200,000
Operating loss carryforwards	396,700,000	363,300,000
Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward expiration date	expire in 2008 and will continue through 2032
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	392,600,000	360,100,000
Federal and State Net Operating Loss, Stock Based Compensation [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	5,200,000	400,000
PENNSYLVANIA
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 358,000,000