Debt - Term Debt Narrative (Details) (USD $)	0 Months Ended						0 Months Ended	1 Months Ended		0 Months Ended		1 Months Ended
	Jul. 27, 2012	Jul. 18, 2011	Dec. 31, 2013	Dec. 31, 2012	Jul. 31, 2012	Dec. 31, 2009	Jul. 30, 2012 Oxford/SVB [Member]	Jun. 30, 2011 Oxford/SVB [Member]	Dec. 31, 2011 Oxford/SVB [Member]	Jul. 30, 2012 Oxford/SVB [Member] Revolving Credit Facility [Member]	Jun. 30, 2008 Oxford/SVB [Member] Loan And Security Agreement [Member]	Jun. 30, 2011 Minimum [Member] Oxford/SVB [Member]	Jun. 30, 2011 Maximum [Member] Oxford/SVB [Member]
Debt Instrument [Line Items]
Debt instrument, outstanding											$ 18,000,000
Warrant exercisable to Healthcare Royalty, shares		225,000						26,455
Warrants exercise price (in usd per share)	$ 2.50							$ 3.78
Term of common stock warrant exercisable	5 years	10 years						7 years
Debt discount									76,000
Fair value of warrant liabilities			30,849,000	9,308,000
Long term debt under loan and security agreement					25,000,000			25,000,000	25,000,000
Revolving credit facility						200,000		10,000,000
Interest rate								12.06%
Revolving credit facility, interest rate description								equal to the greater of 3.29% above SVB's prime rate or 7.29%
Revolving credit facility, interest rate												3.29%	7.29%
Percentage paid for unused portion of revolving credit facility								0.50%
Amount outstanding under revolving credit facility									5,151,000
Principal and interest repaid							19,492,000
Final payment to terminate debt							1,200,000
Percentage of principal as perpayment premium							2.00%
Prepayment Premium To Terminate Debt							$ 400,000			$ 100,000