Summary of Significant Accounting Policies - Stock-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Summary of Significant Accounting Policies
Expected term	4 years	4 years
Expected volatility (as a percent)	69.08%	78.31%
Risk free rate (as a percent)	1.40%	1.26%