Fourth Quarter Financial Data (Unaudited) - Basic and Diluted Net Income (Loss) Per Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income	$ 10,808	$ 17,000	$ 15,566	$ (34,382)	$ (24,753)
Less: change in fair value of common stock warrants	32	(2,819)
Net income - diluted	$ 10,840	$ 14,181	$ 15,566
Weighted average shares outstanding - basic (in shares)	63,650	62,249	63,000	60,990	58,507
Dilutive common share equivalents:
Common stock (in shares)			157
Weighted average shares outstanding - diluted (in shares)	65,927	65,678	64,349	60,990	58,507
Options to purchase common stock
Dilutive common share equivalents:
Common stock (in shares)	1,877	2,984
Unvested restricted stock units
Dilutive common share equivalents:
Common stock (in shares)	227	133
Warrants to purchase common stock
Dilutive common share equivalents:
Common stock (in shares)	170	308
Awards to be granted under the ESPP
Dilutive common share equivalents:
Unvested and granted (in shares)	3	4
Convertible senior notes (if-converted)
Dilutive common share equivalents:
Convertible senior notes (if-converted) (in shares)	0	0