Stock-Based Compensation Plans (Tables)

9 Months Ended

Sep. 30, 2018

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

Schedule of Stock Valuation Assumptions

The following assumptions were used in the valuation of stock options granted in 2018:

	2018
Expected volatility	31.0%
Risk-free interest rate range	1.99% to 2.58%
Expected life in years	6.8
Expected dividend yield	—

Stock Option Transactions for Employee Stock Option Plans

Stock option transactions for the third quarter and nine months ended September 30, 2018 are summarized as follows:

	2018
	Third Quarter				Nine Months
	Shares		Weighted Average Exercise Price		Shares		Weighted Average Exercise Price
Beginning balance	2,290,893		$	103.11	2,285,703		$	83.73
Granted	2,580		$	231.98	377,472		$	192.28
Exercised	(163,702	)	$	75.13	(504,674	)	$	71.63
Canceled	(51,467	)	$	139.87	(80,197	)	$	130.87
Ending balance	2,078,304		$	104.57	2,078,304		$	104.57
Options exercisable at end of period	1,270,019		$	78.32	1,270,019		$	78.32

Schedule of Restricted Stock Activity

The following table shows the restricted stock activity for the first nine months of 2018:

	Shares		Weighted average fair value per share
Balance, December 31, 2017	88,436		$	90.63
Granted	16,733		$	171.80
Vested	(28,855	)	$	92.74
Forfeited/Canceled	(2,994	)	$	118.55
Balance, September 30, 2018	73,320		$	107.19