Summary of Stock Option Activity (Detail) - Stock Option Awards $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($) $ / shares shares
Options outstanding, shares
Beginning Balance | shares	1,157
Granted | shares	280
Exercised | shares	(159)
Forfeited/Expired | shares	(5)
Ending Balance | shares	1,273
Exercisable as of March 31, 2021 | shares	564
Expected to vest as of March 31, 2021 | shares	709
Total | shares	1,273
Weighted Average Exercise Price Per Share
Beginning Balance | $ / shares	$ 139.48
Granted | $ / shares	691.93
Exercised | $ / shares	150.43
Forfeited/Expired | $ / shares	138.82
Ending Balance | $ / shares	259.39
Exercisable as of March 31, 2021 | $ / shares	132.02
Expected to vest as of March 31, 2021 | $ / shares	360.60
Total | $ / shares	$ 259.39
Aggregate Intrinsic Value
Exercised | $	$ 98,332
Exercisable as of March 31, 2021 | $	308,274
Expected to vest as of March 31, 2021 | $	229,435
Total | $	$ 537,709
Weighted Average Remaining Contractual Term (Years)
Exercisable as of March 31, 2021	3 years 10 months 24 days
Expected to vest as of March 31, 2021	9 years
Total	6 years 8 months 12 days