Deerfield Loan (Details) $ / shares in Units, $ in Thousands, shares in Millions			3 Months Ended		6 Months Ended
	Jul. 29, 2015 USD ($)	Jul. 22, 2015 USD ($)	Jun. 30, 2015 USD ($) Installment $ / shares shares	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) Installment $ / shares shares	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Carrying value of Facility Agreement [Abstract]
Note payable			$ 30,000		$ 30,000		$ 30,000
Unamortized discount			(8,549)		(8,549)		(9,698)
Long-term debt, net of discount			$ 21,451		$ 21,451		$ 20,302
Number of loan installments | Installment			3		3
Principal amount of loan payable, installment amount					$ 10,000
Interest expense [Abstract]
Cash interest rate under loan facility (in hundredths)			8.75%		8.75%
Deerfield Debt Restructuring [Member]
Interest expense [Abstract]
Deferred period for loan payment					1 year
Subsequent Event [Member] | Deerfield Debt Restructuring [Member]
Carrying value of Facility Agreement [Abstract]
Principal amount of loan payable, installment amount	$ 12,500	$ 5,000
Principal amount of loan payable, future interest obligation		$ 5,000
Interest expense [Abstract]
Cash interest rate under loan facility (in hundredths)		8.25%
Deerfield Management Company [Member]
Interest expense [Abstract]
Cash interest expense			$ 654	$ 654	$ 1,301	$ 1,302
Non-cash amortization of debt discounts			594	470	1,149	909
Amortization of debt costs			5	5	10	10
Total interest expense			$ 1,253	$ 1,129	$ 2,460	$ 2,221
Number of shares under issued warrants (in shares) | shares			7.0		7.0
Exercise price of warrants (in dollars per share) | $ / shares			$ 2.81		$ 2.81
Deerfield Management Company [Member] | Subsequent Event [Member]
Carrying value of Facility Agreement [Abstract]
Principal amount of loan payable, installment amount		$ 5,000
Interest expense [Abstract]
Cash interest rate under loan facility after decreasing (in hundredths)		8.25%