Equity Awards - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2021
Number of Shares
Outstanding, beginning balance (in shares)	484,000	454,000	522,000	522,000
Granted (in shares)		54,000	36,000
Exercised (in shares)	(98,000)	(24,000)	(104,000)
Outstanding, ending balance (in shares)	386,000	484,000	454,000	386,000
Vested and expected to vest (in shares)	352,000			352,000
Vested and exercisable (in shares)	205,000			205,000
Weighted- Average Exercise Price Per Share
Outstanding, beginning balance (in dollars per share)	$ 147.70	$ 149.23	$ 107.14	$ 107.14
Granted (in dollars per share)		77.96	587.91
Exercised (in dollars per share)	48.26	16.46	88.28
Outstanding, ending balance (in dollars per share)	172.85	$ 147.70	$ 149.23	172.85
Vested and expected to vest (in dollars per share)	165.12			165.12
Vested and exercisable (in dollars per share)	$ 74.71			$ 74.71
Weighted-average remaining contractual term, outstanding				5 years 8 months 12 days
Weighted-average remaining contractual term, vested and expected to vest				5 years 6 months
Weighted-average remaining contractual term, vested and exercisable				3 years 3 months 18 days
Aggregate intrinsic value, exercised	$ 55	$ 11	$ 47
Aggregate intrinsic value, outstanding	174			$ 174
Aggregate intrinsic value, vested and expected to vest	161			161
Aggregate intrinsic value, vested and exercisable	$ 112			$ 112