Summary of Significant Accounting Policies (Details) - Reconciliation of the warrant liability measured at fair value using Level 3 inputs (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Reconciliation of the warrant liability measured at fair value using Level 3 inputs [Abstract]
Balance at beginning of period	$ 939	$ 10
Issuance of common stock warrants	1,531	749
Exercise of common stock warrants	(2,505)
Remeasurement of common stock warrants	945	151
Balance at end of period	$ 910	$ 910