STOCK PLANS (Tables)

12 Months Ended

Dec. 31, 2015

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

Summary of stock option activity

The following table summarizes stock option activity for the years ended December 31, 2015, 2014 and 2013, under all Plans:

	Year Ended December 31,
	2015				2014				2013
	Options		Weighted Average Exercise Price		Options		Weighted Average Exercise Price		Options		Weighted Average Exercise Price
Balance at beginning of year	2,087,193		$	37.80	2,452,648		$	36.52	3,060,944		$	30.98
Options granted	323,130		69.14		5,121		69.61		273,105		70.88
Options exercised	(197,582	)	30.35		(329,986	)	27.63		(774,783	)	26.20
Options canceled	(18,092	)	66.51		(40,590	)	47.21		(106,618	)	40.54
Balance at end of year	2,194,649		42.85		2,087,193		37.80		2,452,648		36.52
Exercisable at end of year	1,807,427		37.15		1,818,218		33.89		1,837,014		29.93

Weighted average assumptions used for estimating fair value of options granted

The weighted average assumptions for each of the three years ended December 31, 2015 were as follows:

	Year Ended December 31,
	2015			2014			2013
Expected volatility	30.73		%	32.21		%	32.97		%
Dividend yield	1.48		%	1.41		%	1.40		%
Risk-free interest rate	1.32		%	1.61		%	1.52		%
Expected option life (years)	4.5			4.4			4.4
Weighted average fair value per option granted during the year	$	16.35		$	17.52		$	18.14

Summary of nonvested stock options

The following table summarizes non-vested stock options for the year ended December 31, 2015:

	Year Ended December 31, 2015
	Number of Options		Weighted Average Fair Value at Grant Date
Balance at beginning of year	268,975		$	17.48
Granted	323,130		16.35
Vested	(189,681	)	17.26
Forfeited	(15,202	)	17.15
Balance at end of year	387,222		16.66

Summary of information about awards outstanding, by exercise price range

The following table summarizes information about awards outstanding as of December 31, 2015:

	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 $29.99	491,072	$	24.56	3.5	491,072	$	24.56	3.5
$30.00 - $39.99	825,161	33.18		4.4	825,161	33.18		4.4
Over $40.00	878,416	62.15		8.0	491,194	56.40		7.3
	2,194,649			5.7	1,807,427			5.0

Summary of restricted share award activity

The following table summarizes restricted share award activity for the years ended December 31, 2015, 2014 and 2013, under all Plans:

	Year Ended December 31,
	2015				2014				2013
	Shares		Weighted Average Grant Date Fair Value		Shares		Weighted Average Grant Date Fair Value		Shares		Weighted Average Grant Date Fair Value
Balance at beginning of year	49,490		$	60.14	115,316		$	39.55	336,808		$	28.49
Shares granted	20,476		53.94		14,927		66.32		14,464		70.88
Shares vested	(20,745	)	49.37		(80,753	)	31.88		(224,021	)	25.68
Shares forfeited	(4,592	)	64.61		—		—		(11,935	)	25.76
Balance at end of year	44,629		61.84		49,490		60.14		115,316		39.55

Summary of restricted stock unit activity

The following table summarizes restricted stock unit activity for the years ended December 31, 2015, 2014 and 2013, under all Plans:

	Year Ended December 31,
	2015				2014				2013
	Units		Weighted Average Grant Date Fair Value		Units		Weighted Average Grant Date Fair Value		Units		Weighted Average Grant Date Fair Value
Balance at beginning of year	241,496		$	49.34	283,944		$	47.38	288,669		$	40.83
Units granted	67,800		68.82		2,861		70.71		69,925		67.17
Units vested	(76,996	)	37.21		(40,035	)	36.59		(33,698	)	39.20
Units forfeited	(10,768	)	57.98		(5,274	)	52.19		(40,952	)	41.70
Balance at end of year	221,532		59.10		241,496		49.34		283,944		47.38