Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Liabilities:
Liability	$ 0
Recurring | Measured at fair value
Assets:
Money market funds	72,005	$ 13,506
Total assets at fair value	72,005	13,506
Liabilities:
Total liabilities at fair value		108
Recurring | Measured at fair value | Warrant Liability
Liabilities:
Liability		108
Recurring | Measured at fair value | Level 1
Assets:
Money market funds	72,005	13,506
Total assets at fair value	$ 72,005	13,506
Recurring | Measured at fair value | Level 3 | Warrant Liability
Liabilities:
Liability		$ 108