Long-Term Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of transactions involving stock option awards

Transactions involving stock option awards during 2018 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, 2017		26,205,373		$	295.98
2018:	Granted	4,665,320		$	378.51
	Forfeited	(668,550	)	$	422.56
	Expired	(205,030	)	$	467.40
	Exercised	(1,717,417	)	$	66.87
Outstanding as of December 31, 2018		28,279,696		$	319.28	6.43	$	2,290.5
Vested and expected to vest as of December 31, 2018		27,192,461		$	316.51	6.32	$	2,289.1
Exercisable as of December 31, 2018		17,893,976		$	275.10	4.98	$	2,276.2

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

The fair value of each option granted under the Company's Incentive Plans during these periods was estimated on the date of grant using the Black-Scholes option-pricing model.

	Number of Options Granted	Weighted-Average Exercise Price		Weighted-Average Fair Value
2018:
Exercise price equal to Market Price	4,665,320	$	378.51	$	114.39
2017:
Exercise price equal to Market Price	4,235,015	$	383.56	$	118.70
2016:
Exercise price equal to Market Price	4,201,978	$	386.44	$	126.68

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 2018, 2017, and 2016.

	2018		2017		2016
Expected volatility	29	%	31	%	34	%
Expected lives from grant date	4.9 years		5.1 years		5.1 years
Expected dividend yield	0	%	0	%	0	%
Risk-free interest rate	2.69	%	2.16	%	1.84	%

Schedule of activity related to restricted stock awards

A summary of the Company's activity related to restricted stock awards and restricted stock units (collectively, "restricted stock") during 2018 is summarized below:

		Number of Shares/Units		Weighted-Average Grant Date Fair Value
Balance as of December 31, 2017		106,260		$	404.72
2018:	Granted	380,980		$	381.21
	Vested	(6,090	)	$	276.46
	Forfeited/Cancelled	(8,520	)	$	478.19
Balance as of December 31, 2018		472,630		$	386.10