Activity Under Equity Incentive Plans Related to RSUs (Detail) - 2008 Equity Incentive Plan - Restricted Stock Units shares in Thousands	3 Months Ended
	Mar. 31, 2023 $ / shares shares
Activity under the Company's equity incentive plans related to restricted stock units
Number of Restricted Stock Units Unvested, Beginning Balance | shares	8,497
Granted, Number of Restricted Stock Units Unvested | shares	5,409	[1]
Vested, Number of Restricted Stock Units Unvested | shares	(2,688)	[1]
Forfeited, Number of Restricted Stock Units Unvested | shares	(245)	[1]
Number of Restricted Stock Units Unvested, Ending Balance | shares	10,973
Weighted Average Exercise Price per Share
Weighted Average Exercise Price per Share, Beginning Balance | $ / shares	$ 5.76
Granted, Weighted Average Exercise Price per Share | $ / shares	2.66	[1]
Vested, Weighted Average Exercise Price per Share | $ / shares	5.77	[1]
Forfeited, Weighted Average Exercise Price per Share | $ / shares	5.32	[1]
Weighted Average Exercise Price per Share, Ending Balance | $ / shares	$ 4.24

[1] Includes shares issuable under performance-based restricted stock unit awards.