Equity Awards - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($) $ / shares shares
Number of Shares
Outstanding, beginning balance (in shares) | shares	522,000
Granted (in shares) | shares	36,000
Exercised (in shares) | shares	(104,000)
Outstanding, ending balance (in shares) | shares	454,000
Vested and expected to vest (in shares) | shares	429,000
Vested and exercisable (in shares) | shares	298,000
Weighted- Average Exercise Price Per Share
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 107.14
Granted (in dollars per share) | $ / shares	587.91
Exercised (in dollars per share) | $ / shares	88.28
Outstanding, ending balance (in dollars per share) | $ / shares	149.23
Vested and expected to vest (in dollars per share) | $ / shares	137.40
Vested and exercisable (in dollars per share) | $ / shares	$ 50.86
Weighted-average remaining contractual term, outstanding	5 years
Weighted-average remaining contractual term, vested and expected to vest	4 years 8 months 12 days
Weighted-average remaining contractual term, vested and exercisable	2 years 10 months 24 days
Aggregate intrinsic value, exercised | $	$ 47
Aggregate intrinsic value, vested and expected to vest | $	158
Aggregate intrinsic value, vested and exercisable | $	$ 134