Stock-based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2018

Information on the Company’s stock options is summarized below.

YEARS ENDED DECEMBER 31	2018					2017					2016
(in whole shares and dollars)	Shares			Weighted Average Exercise Price		Shares			Weighted Average Exercise Price		Shares			Weighted Average Exercise Price
Outstanding, beginning of year		1,062,177		$	75.53		1,396,152		$	68.63		1,619,948		$	56.57
Granted		301,152			110.98		460,610			90.85		587,340			82.17
Exercised		(210,190	)		69.41		(464,726	)		63.12		(589,666	)		48.99
Forfeited or cancelled		(54,063	)		89.09		(329,859	)		85.22		(221,470	)		68.61
Outstanding, end of year		1,099,076		$	85.75		1,062,177		$	75.53		1,396,152		$	68.63
Exercisable, end of year		515,286		$	69.83		423,883		$	62.41		441,256		$	53.59

Additional information about employee options outstanding and exercisable at December 31, 2018 is included in the following table:

		Options Outstanding						Options Currently Exercisable
Range of Exercise Prices		Number		Weighted Average Remaining Contractual Lives		Weighted Average Exercise Price		Number		Weighted Average Exercise Price
$	36.81 to $46.47		64,367		3.44	$	41.61		64,367	$	41.61
$	57.99		93,778		5.14		57.99		93,778		57.99
$	70.24 to $72.66		165,924		6.16		70.27		165,924		70.27
$	74.88 to $82.74		190,120		7.30		80.75		112,847		80.49
$	87.50 to $91.19		285,280		8.20		90.66		78,370		90.89
$	110.57 to $124.14		299,607		9.18		110.98		—		—

The following significant assumptions were used to determine the fair value for options granted in the years indicated.

	2018		2017		2016
Dividend yield	1.740% to 1.954	%	2.193% to 2.286	%	2.04% to 2.46	%
Expected volatility	17.943% to 18.500	%	18.341% to 21.694	%	18.08% to 21.31	%
Weighted average expected volatility	18.20	%	19.52	%	19.57	%
Risk-free interest rate	2.365% to 2.969	%	1.324% to 2.201	%	0.77% to 1.97	%
Expected term, in years	2.5 to 6.0		2.5 to 6.0		2.5 to 5.5

The following table summarizes information about employee restricted stock units:

YEARS ENDED DECEMBER 31	2018					2017					2016
	Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value
Time-based restricted stock units:
Outstanding, beginning of year		298,528		$	83.45		269,063		$	73.91		301,897		$	54.54
Granted		152,529			111.66		130,075			90.40		143,107			83.43
Vested		(72,710	)		72.69		(70,590	)		59.29		(139,183	)		42.97
Forfeited ⁽¹⁾		(45,866	)		94.04		(30,020	)		84.88		(36,758	)		69.07
Outstanding, end of year		332,481		$	97.28		298,528		$	83.45		269,063		$	73.91
Performance and market-based restricted stock units:
Outstanding, beginning of year		102,586		$	81.21		115,057		$	78.82		196,142		$	47.89
Granted		35,063			118.60		60,101			79.48		126,796			73.42
Vested		(14,032	)		70.24		(17,642	)		56.45		(144,141	)		40.95
Forfeited ⁽¹⁾		(53,779	)		89.79		(54,930	)		82.27		(63,740	)		58.54
Outstanding, end of year ⁽²⁾		69,838		$	95.58		102,586		$	81.21		115,057		$	78.82

(1)	As a result of the sale of Chaucer and included in forfeitures in 2018 are 19,655 shares of time-based restricted stock units, 43,449 shares of performance-based restricted stock units and 2,705 shares of market-based restricted stock units that were awarded to Chaucer employees.

(2)	At December 31, 2018, only market-based awards were outstanding.