Summary of Significant Accounting Policies - Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share Due to Anti-Dilutive Effect (Detail) - shares	3 Months Ended				12 Months Ended
	Mar. 31, 2022		Mar. 31, 2021		Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	7,698,000		8,072,000
Options to Purchase Common Stock, Including Purchases from Contributions to ESPP [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	7,123,000		7,483,000
Unvested Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	560,000		425,000
Restricted Stock Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	15,000		14,000
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	0	[1]	150,000	[1]	150,000

[1] In 2012, the Company issued a warrant with a ten-year term to purchase 150,000 shares of its common stock at an exercise price of $20.00 per share. The warrant was exercised in January 2022.