Summary of Significant Accounting Policies - Antidilutive Securities (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities	11,736,603	12,789,661	11,804,131	13,057,390
Common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities	2,112,690	2,371,908	2,145,789	2,347,335
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities	9,623,913	10,417,753	9,658,342	10,710,055