Share-Based Compensation - Summary of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding stock options, Beginning balance | shares	7,285
Options granted | shares	1,370
Options exercised | shares	(1,028)
Options forfeited | shares	(175)
Options expired | shares	(29)
Outstanding stock options, Ending Balance | shares	7,423
Number of outstanding options, Vested or expected to vest | shares	7,205
Exercisable, Stock options | shares	4,581
Outstanding Weighted average exercise price, Beginning Balance | $ / shares	$ 107.53
Options granted, Weighted average exercise price | $ / shares	155.68
Options exercised, Weighted average exercise price | $ / shares	100.69
Options forfeited, Weighted average exercise price | $ / shares	135.54
Options expired, Weighted average exercise price | $ / shares	113.53
Outstanding Weighted average exercise price, ending Balance | $ / shares	116.67
Outstanding Weighted average exercise price, Vested or expected to vest | $ / shares	115.92
Exercisable, Weighted average exercise price | $ / shares	$ 104.20
Weighted Average Remaining Contractual Life, Outstanding at December 31, 2020	6 years 3 months 18 days
Weighted Average Remaining Contractual Life, Vested or expected to vest as of December 31, 2020	6 years 2 months 12 days
Weighted Average Remaining Contractual Life, Exercisable at December 31, 2020	5 years
Intrinsic Value, Outstanding at December 31, 2020 | $	$ 282.0
Intrinsic Value, Vested or expected to vest as of December 31, 2020 | $	278.8
Intrinsic Value, Exercisable at December 31, 2020 | $	$ 228.5