Common Stock and Stockholders' Equity (Deficit) - Warrants (Details) - Common stock warrants $ / shares in Units, $ in Millions	Dec. 22, 2015 $ / shares shares	Jul. 24, 2015 $ / shares shares	May 02, 2014 USD ($) item $ / shares shares	Jun. 30, 2016 shares	Dec. 31, 2015 shares
Warrants
Number of warrants issued			131,239
Number of shares that may be exercised from warrants			131,239
Number of shares issued upon exercise of warrants	54,830	59,281
Cashless exercise of warrants (in shares)	65,619	65,620
Exercise price of warrants (in dollars per share) | $ / shares	$ 2.95	$ 2.95	$ 2.95
Number of affiliates of lender granted warrants | item			2
Term of warrants			10 years
Fair value of common stock warrants | $			$ 0.2
Warrants outstanding (in shares)				0	0