Significant Accounting Policies - Schedule of Computation of Diluted EPS (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss (in shares)	9,505,323	9,226,277	7,662,325
Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss (in shares)	8,588,614	8,425,551	6,935,119
Stock purchase warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss (in shares)	0	4,500	154,500
Nonvested restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss (in shares)	809,527	754,415	572,706
Nonvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss (in shares)	107,182	41,811	0