Net Income (Loss) Per Share - Antidilutive Shares Excluded from Computation of Diluted Net Income (Loss) Per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Totals	20,505,086	20,089,927
Common stock issuable under outstanding convertible notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Totals	10,377,361	10,377,361
Shares subject to outstanding options to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Totals	2,163,682	2,155,199
Unvested restricted stock units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Totals	7,071,933	6,471,549
Shares subject to warrants to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Totals	432,240	479,002
Shares issuable under employee stock purchase plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Totals	459,870	606,816