Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2016

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

The following table summarizes the Company’s stock option activity and related information for the 2011 Plan, the 2000 Plan and the Directors Plan for the six months ended June 30, 2016:



	Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life	Aggregate Intrinsic value (in thousands)
Outstanding at December 31, 2015	1,097,323		$	32.70	4.8	$	42,154
Granted	94,115		61.39			828
Exercised	(26,150	)	26.89			1,132
Canceled	(5,321	)	69.37			4
Outstanding at June 30, 2016	1,159,967		35.00		4.7	40,825
Exercisable at June 30, 2016	941,442		27.17		3.9	40,501

Share-Based Fair Value of Each Option Grant Weighted-Average Assumptions

The fair value of each option grant is estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions:



	Six Months Ended June 30,
	2016		2015
Dividend yield	0.26	%	0.14	%
Risk-free interest rate	1.47	%	1.82	%
Stock price volatility	26.9	%	27.3	%
Expected life (years)	5.0		5.0

Restricted Stock Activity and Incentive Stock Awards Activity

The following table summarizes the restricted stock activity and related information for the 2011 Plan, the 2000 Plan and the Directors Plan, and incentive stock units activity for the 2011 Plan and the 2000 Plan with related information for the six months ended June 30, 2016:



	Restricted Stock and Units		Incentive Stock Awards		Weighted Average Grant Date Fair Value
Outstanding at December 31, 2015	356,885		541,638		$	65.89
Granted	142,891		167,850		62.20
Vested	(148,753	)	(236,591	)	52.12
Adjustment for incentive stock awards expected to vest	—		(27,784	)	73.28
Canceled	(7,519	)	(5,283	)	70.48
Outstanding at June 30, 2016	343,504		439,830		70.85