Fair Value Measurements - Series A Preferred Stock - (Details) - Series A Preferred Stock Tranche Liability - Probability Weighted Present Value Model $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2014 USD ($) $ / shares
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Probability of closing tranche	67.00%
Estimated future value at closing | $ / shares	$ 1.51
Investment required | $	$ 20
Discount Rate	(16.20%)