Stock Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Option pricing valuation model for options granted

The assumptions used in the Black-Scholes option pricing valuation model for options granted by the Company in 2019, 2018 and 2017 are as follows:

	2019		2018		2017
Risk-free interest rate	2.51	%	2.73	%	2.09	%
Expected life (in years)	6.0		6.0		6.0
Expected volatility	20.93	%	23.23	%	23.23	%
Expected dividend yield	1.82	%	1.81	%	1.86	%

Summary of the status of MMC's stock option awards

A summary of the status of the Company’s stock option awards as of December 31, 2019 and changes during the year then ended is presented below:

	Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value ($000)
Balance at January 1, 2019	9,968,038		$	53.94
Granted	1,661,590		$	91.15
Exercised	(2,655,288	)	$	40.10
Forfeited	(115,212	)	$	82.96
Balance at December 31, 2019	8,859,128		$	64.69	6.2 years	$	414,756
Options vested or expected to vest at December 31, 2019	8,714,264		$	64.43	6.1 years	$	410,231
Options exercisable at December 31, 2019	5,133,064		$	52.36	4.7 Years	$	303,612

Summary of restricted stock units and performance stock units

A summary of the status of the Company's restricted stock units and performance stock units as of December 31, 2019 and changes during the period then ended is presented below:

	Restricted Stock Units				Performance Stock Units
	Shares		Weighted Average Grant Date Fair Value		Shares		Weighted Average Grant Date Fair Value
Non-vested balance at January 1, 2019	4,330,231		$	76.49	698,798		$	70.33
Granted	4,266,983		$	92.50	245,065		$	91.17
Vested	(2,023,355	)	$	72.96	(262,820	)	$	57.50
Forfeited	(616,122	)	$	89.55	(30,496	)	$	83.30
Non-vested balance at December 31, 2019	5,957,737		$	87.80	650,547		$	82.75