Income Taxes (Details) (USD $)	3 Months Ended			12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes
Current Income Tax Expense (Benefit)	$ (61,000)	$ (299,000)	$ (494,000)		$ (854,000)	$ (1,170,000)
Reconciliation of statutory U.S. federal income tax rate to effective income tax rate
Statutory U.S. federal tax rate (as a percent)				(34.00%)	(34.00%)	(34.00%)
State taxes, net of federal benefit (as a percent)				2.40%	4.20%	(3.40%)
Equity-based compensation expense (as a percent)				9.40%	42.40%	2.40%
Permanent items, net (as a percent)				5.30%	1.20%	0.40%
Tax credits (as a percent)				0.50%	0.80%	(1.60%)
Valuation allowance (as a percent)				16.40%	(19.50%)	34.70%
Total tax (benefit) expense (as a percent)				0.00%	(4.90%)	(1.50%)
Assets
Net operating loss carryforwards	75,740,000			85,269,000	75,740,000
Tax credit carryforwards	12,403,000			12,396,000	12,403,000
Deferred revenue	22,315,000			20,368,000	22,315,000
Equity-based compensation expense	3,681,000			4,176,000	3,681,000
Capitalized research & development	45,137,000			39,214,000	45,137,000
Intangibles				680,000
Other	4,239,000			4,371,000	4,239,000
Property and Equipment Depreciation	1,393,000				1,393,000
Liabilities
Property, Plant, and Equipment Depreciation				(58,000)
Gross deferred taxes	164,908,000			166,416,000	164,908,000
Valuation allowance	(164,908,000)			(166,416,000)	(164,908,000)
Increase (Decrease) in valuation allowance				$ 1,500,000	$ (2,800,000)	$ 26,800,000