STOCK PLANS (Tables)

12 Months Ended

Dec. 31, 2018

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

Summary of stock option activity

The following table summarizes stock option activity for the year ended December 31, 2018 under all Plans:

	Number of Options		Weighted Average Exercise Price
Balance at beginning of year	1,362,448		$	58.45
Options granted	171,843		90.70
Options exercised	(101,272	)	46.20
Options canceled	(1,981	)	58.79
Balance at end of year	1,431,038		63.19
Exercisable at end of year	1,070,594		56.70

Weighted average assumptions used for estimating fair value of options granted

The weighted average assumptions for each of the three years ended December 31 were as follows:

	2018			2017			2016
Expected volatility	25.36		%	25.77		%	28.86		%
Dividend yield	1.92		%	1.62		%	1.70		%
Risk-free interest rate	2.69		%	1.90		%	1.27		%
Expected option life (years)	4.6			4.5			4.5
Weighted average fair value per option granted during the year	$	18.97		$	17.50		$	12.55

Summary of nonvested stock options

The following table summarizes non-vested stock options for the year ended December 31, 2018:

	Number of Options		Weighted Average Fair Value at Grant Date
Balance at beginning of year	409,559		$	15.47
Granted	171,843		18.97
Vested	(220,958	)	15.75
Balance at end of year	360,444		17.21

Summary of information about awards outstanding, by exercise price range

The following table summarizes information about awards outstanding as of December 31, 2018:

	Outstanding				Exercisable
Exercise Price Range	Number of Stock Options	Weighted Average Exercise Price		Weighted Average Remaining Life (years)	Number of Stock Options	Weighted Average Exercise Price		Weighted Average Remaining Life (years)
Under $49.99	447,315	$	39.78	3.0	447,315	$	39.79	3.0
$50.00 - $59.99	217,143	58.12		7.1	144,768	58.11		7.1
Over $60.00	766,580	78.28		7.0	478,511	72.09		5.9
	1,431,038			5.8	1,070,594			4.9

Summary of restricted share award activity

The following table summarizes restricted share award activity for the year ended December 31, 2018 under all Plans:

	Number of Shares		Weighted Average Grant Date Fair Value
Balance at beginning of year	47,856		$	71.54
Shares granted	1,662		91.02
Shares vested	(32,922	)	82.48
Shares forfeited	(4,158	)	78.65
Balance at end of year	12,438		80.98

Summary of restricted stock unit activity

The following table summarizes RSU and PSU activity for the year ended December 31, 2018 under all Plans:

	Number of Units		Weighted Average Grant Date Fair Value
Balance at beginning of year	418,966		$	69.98
Units granted	148,833		89.51
Units vested	(49,653	)	69.24
Units forfeited	(12,116	)	74.16
Balance at end of year	506,030		75.69