STOCK-BASED COMPENSATION (Tables)

Presented below is a summary of the stock-based compensation expense and associated tax benefit in the accompanying Consolidated Statements of Operations:


	Year Ended December 31,
	2019		2018		2017
Stock-based compensation expense	$	136	$	130	$	123
Tax benefit	$	29	$	32	$	13	^'(1)

⁽¹⁾The 2017 Amount includes a decrease in deferred tax assets resulting from a future reduction in the U.S. federal corporate income tax rate in accordance with the Tax Act.

The following weighted average assumptions were used for options granted:


	Year Ended December 31,
	2019			2018			2017
Expected dividend yield	1.14		%	1.05		%	1.34		%
Expected stock volatility	24		%	26		%	27		%
Risk-free interest rate	2.56		%	2.82		%	2.19		%
Expected holding period -in years	6.2			6.2			6.5
Grant date fair value	$	43.29		$	45.73		$	30.00

A summary of option activity as of December 31, 2019 and changes during the year then ended is presented below:


Options	Shares	Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding, December 31, 2018	2.2	$	69.86
Granted	0.2	175.30
Exercised	(0.8)	44.59
Outstanding, December 31, 2019	1.6	93.51		5.2 years	$	227
Vested and expected to vest, December 31, 2019	1.5	92.14		5.1 years	$	224
Exercisable, December 31, 2019	1.1	$	71.64	4.0 years	$	176

The following table summarizes information relating to stock option exercises:


	Year Ended December 31,
	2019	2018	2017
Proceeds from stock option exercises	36	38	49
Aggregate intrinsic value	114	99	88
Tax benefit realized upon exercise	27	24	31

A summary of nonvested restricted stock activity for the year ended December 31, 2019 is presented below:


Nonvested Restricted Stock	Shares	Weighted Average Grant Date Fair Value Per Share
Balance, December 31, 2018	2.0	$	123.13
Granted	0.8	174.07
Vested	(0.9)	113.21
Forfeited	(0.1)	144.18
Balance, December 31, 2019	1.8	$	124.63

The following table summarizes information relating to the vesting of restricted stock awards:


	Year Ended December 31,
	2019	2018	2017
Fair value of shares vested	156	151	111
Tax benefit realized upon vesting	36	35	35

A summary of performance-based restricted stock activity for the year ended December 31, 2019 is presented below:


Performance-based restricted stock	Shares	Weighted Average Grant Date Fair Value Per Share
Balance, December 31, 2018	0.7	$	103.74
Granted	0.1	169.68
Vested	(0.3)	76.68
Balance, December 31, 2019	0.5	$	134.35

The following table summarizes information relating to the vesting of the Company’s performance-based restricted stock awards:


	Year Ended December 31,
	2019	2018	2017
Fair value of shares vested	47	23	20
Tax benefit realized upon vesting	11	6	7