Net Loss per Share - Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-Average Shares (Detail) - shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents outstanding excluded from diluted earnings per share calculation	16,777,801	11,066,008
Stock options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents outstanding excluded from diluted earnings per share calculation	14,204,662	8,956,961
ESPP [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents outstanding excluded from diluted earnings per share calculation	39,744
Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents outstanding excluded from diluted earnings per share calculation	486,812	486,812
Restricted stock units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents outstanding excluded from diluted earnings per share calculation	2,046,583	1,265,151
Performance Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents outstanding excluded from diluted earnings per share calculation		321,666
Deferred Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents outstanding excluded from diluted earnings per share calculation		35,418