Summary of Significant Accounting Policies - Anti-dilutive securities (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share
Anti-dilutive securities	2,062,195	2,036,070	4,826,558
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Anti-dilutive securities			3,704,126
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share
Anti-dilutive securities	1,808,493	1,637,399	542,550
Restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Anti-dilutive securities	253,702	398,671	579,882