Summary of Company's Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Number of Shares
Options Outstanding, Beginning Balance | shares	17,427,228
Granted | shares	1,937,006
Exercised | shares	(2,571,633)
Cancelled/forfeited | shares	(350,607)
Options Outstanding, Ending Balance | shares	16,441,994
Vested at December 31, 2020 | shares	9,691,855
Unvested at December 31, 2020 | shares	6,750,139
Exercisable | shares	9,691,855
Weighted Average Exercise Prices
Weighted Average Exercise Prices, Beginning Balance | $ / shares	$ 28.69
Weighted Average Exercise Prices, granted | $ / shares	43.78
Weighted Average Exercise Prices, exercised | $ / shares	28.71
Weighted Average Exercise Prices, Cancelled/forfeited | $ / shares	31.75
Weighted Average Exercise Prices, Ending Balance | $ / shares	30.40
Weighted Average Exercise Prices, Vested | $ / shares	29.71
Weighted Average Exercise Prices, Unvested | $ / shares	31.38
Weighted Average Exercise Prices, Exercisable | $ / shares	$ 29.71
Weighted average remaining contractual term, Outstanding	6 years 9 months 18 days
Weighted average remaining contractual term, Vested	6 years
Weighted average remaining contractual term, Unvested	8 years
Weighted average remaining contractual term, Exercisable	6 years
Aggregate Intrinsic Value, Outstanding | $	$ 379,233
Aggregate Intrinsic Value, Vested | $	230,156
Aggregate Intrinsic Value, Unvested | $	149,078
Aggregate Intrinsic Value, Exercisable | $	$ 230,156