STOCK PLANS (Tables)

12 Months Ended

Dec. 31, 2019

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, 2019 under all Plans:

	Number of Options		Weighted Average Exercise Price
Balance at beginning of year	1,431,038		$	63.19
Options granted	201,881		88.44
Options exercised	(314,629	)	45.60
Balance at end of year	1,318,290		71.25
Exercisable at end of year	943,715		64.34

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:

	2019			2018			2017
Expected volatility	25.98		%	25.36		%	25.77		%
Dividend yield	2.42		%	1.92		%	1.62		%
Risk-free interest rate	2.49		%	2.69		%	1.90		%
Expected option life (years)	4.6			4.6			4.5
Weighted average fair value per option granted during the year	$	17.46		$	18.97		$	17.50

Summary of nonvested stock options

The following table summarizes non-vested stock options for the year ended December 31, 2019:

	Number of Options		Weighted Average Fair Value at Grant Date
Balance at beginning of year	360,444		$	17.21
Granted	201,881		17.46
Vested	(187,750	)	16.04
Balance at end of year	374,575		17.93

Summary of information about awards outstanding, by exercise price range

The following table summarizes information about awards outstanding as of December 31, 2019:

	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	219,050	$	42.31	2.3	219,050	$	42.31	2.3
$50.00 - $59.99	192,609	58.11		6.1	192,609	58.11		6.1
Over $60.00	906,631	81.04		6.8	532,056	75.67		5.5
	1,318,290			5.9	943,715			4.9

Summary of restricted share award activity

The following table summarizes restricted share award activity for the year ended December 31, 2019 under all Plans:

	Number of Shares		Weighted Average Grant Date Fair Value
Balance at beginning of year	12,438		$	80.98
Shares vested	(12,438	)	94.71
Balance at end of year	—		—

Summary of restricted stock unit activity

The following table summarizes RSU and PSU activity for the year ended December 31, 2019 under all Plans:

	Number of Units		Weighted Average Grant Date Fair Value
Balance at beginning of year	506,030		$	75.69
Units granted	170,857		87.55
Units vested	(186,224	)	60.69
Units forfeited	(9,534	)	82.30
Balance at end of year	481,129		85.58