Long-Term Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of transactions involving stock option awards

Transactions involving stock option awards during 2020 under the Company's Incentive Plans are summarized in the table below.

		Number of Shares	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Intrinsic Value
Outstanding as of December 31, 2019		28,609,277	$	337.24
2020:	Granted	2,850,590	$	492.60
	Forfeited	(562,629)	$	379.02
	Expired	(56,282)	$	473.77
	Exercised	(9,139,287)	$	281.90
Outstanding as of December 31, 2020		21,701,669	$	379.51	6.34	$	2,347.4
Vested and expected to vest as of December 31, 2020		20,764,534	$	377.23	6.22	$	2,294.1
Exercisable as of December 31, 2020		13,648,899	$	357.65	4.96	$	1,799.1

Schedule of weighted-average exercise prices and weighted-average grant-date fair values of options issued

The table below summarizes the weighted-average exercise prices and weighted-average grant-date fair values of options issued during the years ended December 31, 2020, 2019, and 2018.

	Number of Options Granted	Weighted-Average Exercise Price		Weighted-Average Fair Value
2020:
Exercise price equal to Market Price	2,850,590	$	492.60	$	126.50
2019:
Exercise price equal to Market Price	3,271,222	$	366.65	$	100.80
2018:
Exercise price equal to Market Price	4,665,320	$	378.51	$	114.39

Schedule of weighted-average values of assumptions used in computing fair value of option grants

The following table summarizes the weighted average values of the assumptions used in computing the fair value of option grants during 2020, 2019, and 2018.

	2020		2019		2018
Expected volatility	28	%	28	%	29	%
Expected lives from grant date	5.0 years		5.0 years		4.9 years
Expected dividend yield	0	%	0	%	0	%
Risk-free interest rate	0.47	%	1.74	%	2.69	%

The following table summarizes the weighted average values of the assumptions used in computing the fair value of PSUs during 2020 and 2019.

	2020	2019
Expected volatility	35%	33%
Expected dividend yield	0%	0%
Risk-free interest rate	0.36%	1.63%

Schedule of activity related to restricted stock awards

A summary of the Company's activity related to restricted stock awards and time-based restricted stock units (excluding performance-based restricted stock units, which are detailed further below) (collectively, "restricted stock") during 2020 is summarized below.

		Number of Shares/Units	Weighted-Average Grant Date Fair Value
Balance as of December 31, 2019		1,102,390	$	377.32
2020:	Granted	646,844	$	496.44
	Vested	(15,630)	$	526.62
	Forfeited/Cancelled	(46,061)	$	377.85
Balance as of December 31, 2020		1,687,543	$	421.58

Schedule of activity related to performance-based awards

A summary of the Company's activity related to PSUs during 2020 is summarized below.

		Number of Shares/Units	Weighted-Average Grant Date Fair Value
Balance as of December 31, 2019		59,396	$	198.10
2020:	Granted	1,240,540	$	209.59
	Vested	—	—
	Forfeited/Cancelled	—	—
Balance as of December 31, 2020		1,299,936	$	209.06