Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Second Installment Shares issuable
Net Loss Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding	5,000,000
Options to purchase common stock
Net Loss Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding	3,613,427	1,652,882
Settlement of short-term debt
Net Loss Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding	248,093	248,093
Nonvested restricted stock units
Net Loss Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding	124,442
Warrants to purchase common stock
Net Loss Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding	92,892	93,040
Employee Stock Purchase Plan
Net Loss Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding	2,871
Nonvested restricted stock awards | Common stock
Net Loss Per Share
Securities excluded from the computation of diluted weighted-average shares outstanding		13,259