Notes Payable (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014
Debt obligations
Variable rate of interest (as a percent)	9.00%
Loan And Security Agreement [Member]
Debt obligations
Remainder of 2014	$ 3,154
2015	5,946
2016	5,910
Total minimum payments	15,010
Less amount representing interest	(1,632)
Notes payable, gross	13,378
Discount on notes payable	(82)
Accretion of the final exit fee payment	127
Carrying value of notes payable	$ 13,423