EMPLOYEE BENEFIT PLANS (Tables)

12 Months Ended

Dec. 31, 2018

Retirement Benefits [Abstract]

Stock-Based Compensation Expense

The compensation expense that has been charged against income for these plans was as follows for the years ended December 31,2018, 2017, and 2016:

	2018			2017			2016
	(in millions)
Stock-based compensation expense by type:
Restricted stock	$	124		$	145		$	106
Stock options	13			12			9
Total stock-based compensation expense	137			157			115
Tax benefit recognized	(21		)	(32		)	(20		)
Stock-based compensation expense, net of tax	$	116		$	125		$	95

Activity for Restricted Stock Awards

Activity for our restricted stock was as follows for the year ended December 31, 2018:

	Shares		Weighted- Average Grant-Date Fair Value
	(shares in thousands)
Nonvested restricted stock at December 31, 2017	1,653		$	171.68
Granted	576		276.62
Vested	(1,045	)	185.82
Forfeited	(220	)	180.83
Nonvested restricted stock at December 31, 2018	964		$	213.99

Weighted-Average Fair Value of Stock Options

The fair value was estimated on the date of grant using the Black-Scholes pricing model with the weighted-average assumptions indicated below:

	2018			2017			2016
Weighted-average fair value at grant date	$	63.67		$	49.81		$	37.12
Expected option life (years)	4.1 years			4.1 years			4.2 years
Expected volatility	26.1		%	27.1		%	27.6		%
Risk-free interest rate at grant date	2.5		%	2.0		%	1.1		%
Dividend yield	0.7		%	0.7		%	0.7		%

Activity for Option Plans

Activity for our option plans was as follows for the year ended December 31, 2018:

	Shares  Under Option		Weighted-Average Exercise Price
	(shares in thousands)
Options outstanding at December 31, 2017	863		$	181.44
Granted	143		276.01
Exercised	(320	)	157.44
Forfeited	(9	)	150.59
Options outstanding at December 31, 2018	677		$	213.17
Options exercisable at December 31, 2018	178		$	180.76