Stock Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2011

Stock Based Compensation Plans [Abstract]

Weighted average assumptions used to estimate fair value of stock options

The fair value of stock options was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions used for grants:

	2011			2010			2009
Stock price	$	131.87		$	107.21		$	66.05-$84.90
Risk-free interest rates		2.24	%		3.50	%		4.58	%
Expected lives	10 years			10 years			10 years
Volatility		19.63	%		22.00	%		20.00	%

Summary of stock options activity

A summary of the status of the Company's stock option plans as of December 31, 2011, 2010, and 2009 and changes during the years ended on those dates is presented below:

	2011					2010					2009
	Shares			Weighted- average exercise price		Shares			Weighted- average exercise price		Shares			Weighted- average exercise price
Outstanding at beginning of year		300,642		$	88.11		378,542		$	82.08		393,443		$	80.63
Granted		197,500			131.87		18,214			107.21		32,259			76.68
Exercised		(83,122	)		84.24		(78,381	)		63.97		(18,407	)		38.31
Forfeited and canceled		-			0.00		(17,733	)		105.40		(28,753	)		85.11
Outstanding at end of year		415,020			109.71		300,642			88.11		378,542			82.02
Options exercisable at year end		219,820			92.31		265,770			86.28		329,909			81.37

Summary information of stock options outstanding

The following table summarizes information about stock options outstanding as of December 31, 2011:

		Options outstanding					Options exercisable
Range of		Number outstanding as of December 31,		Weighted- average remaining contractual	Weighted- average exercise		Number exercisable as of December 31,		Weighted- average exercise
exercise prices		2011		life	price		2011		price
$	48.68 - 73.38		50,577	2.8 years	$	61.78		50,577	$	61.78
	79.05 - 125.84		167,693	5.0 years		97.70		148,193		97.15
	126.73 - 132.62		196,750	9.8 years		132.27		21,050		131.66
			415,020	6.8 years		109.71		219,820		92.31

Restricted stock activity

The following table summarizes information about restricted stock outstanding as of December 31, 2011, 2010 and 2009 and changes during the years ended:

	2011					2010					2009
	Shares			Weighted- average grant price		Shares			Weighted- average grant price		Shares			Weighted- average grant price
Unvested at beginning of year		44,877		$	102.46		37,727		$	99.43		30,304		$	119.31
Granted		1,540			134.44		14,415			109.62		18,954			75.77
Vested		(9,532	)		104.71		(6,126	)		102.27		(5,647	)		108.49
Forfeited and canceled		(1,666	)		94.35		(1,139	)		93.92		(5,884	)		116.89
Unvested at end of year		35,219			98.57		44,877			102.46		37,727			99.43