Stock-Based Compensation - Stock Option Activity Under Equity Incentive Plans (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Share-based Payment Arrangement [Abstract]
Number of shares, outstanding, beginning balance (in shares) | shares	14,885
Number of shares, options granted (in shares) | shares	1,654
Number of shares, options exercised (in shares) | shares	(1,669)
Number of shares, options forfeited and canceled (in shares) | shares	(1,233)
Number of shares, outstanding, ending balance (in shares) | shares	13,637
Number of shares, exercisable (in shares) | shares	9,523
Weighted-Average Exercise Price per Share, outstanding, beginning balance (in dollars per share) | $ / shares	$ 25.23
Weighted-Average Exercise Price per Share, options granted (in dollars per share) | $ / shares	19.15
Weighted-Average Exercise Price per Share, options exercised (in dollars per share) | $ / shares	11.69
Weighted-Average Exercise Price per Share, options forfeited and canceled (in dollars per share) | $ / shares	45.70
Weighted-Average Exercise Price per Share, outstanding, ending balance (in dollars per share) | $ / shares	24.30
Weighted-Average Exercise Price per Share, exercisable (in dollars per share) | $ / shares	$ 22.99
Weighted-Average Remaining Contractual Life, outstanding	3 years 11 months 15 days
Weighted-Average Remaining Contractual Life, exercisable	2 years 8 months 15 days
Aggregate Intrinsic Value, outstanding | $	$ 23,478
Aggregate Intrinsic Value, exercisable | $	$ 23,468