Stock Option Plans (Tables)

3 Months Ended

Mar. 31, 2017

Black-Scholes Option Pricing Model with Weighted Average

For purposes of expense recognition, the estimated fair values of the stock option grants are amortized to expense over the options’ vesting period. We estimated the fair value of stock options at the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions:


	2017			2016
Expected dividend yield		2.8	%		3.0	%
Expected risk-free interest rate		2.3	%		1.6	%
Volatility		27.2	%		27.7	%
Expected life (in years)		5.0			5.5

Stock Option Activity and Related Information

The following is a summary of our stock option activity and related information for 2017 (in millions, except exercise price and year data):


	Three-month period ended March 31, 2017
	Shares Under Option			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value





Beginning balance		10.3		$	41.40
Granted		1.6			56.86
Exercised		(0.7	)		30.98
Forfeited or canceled		—			—

Ending balance		11.2		$	44.35		4.53	$	137.4

Exercisable at end of period		3.2		$	37.28		2.38	$	61.5

Ending vested and expected to vest		11.0		$	44.26		4.50	$	135.6

Other Information Regarding Stock Options Outstanding and Exercisable

Other information regarding stock options outstanding and exercisable at March 31, 2017 is summarized as follows (in millions, except exercise price and year data):


					Options Outstanding						Options Exercisable
Range of Exercise Prices					Number Outstanding		Weighted Average Remaining Contractual Term (in years)		Weighted Average Exercise Price		Number Exercisable		Weighted Average Exercise Price
$	23.76	-	$	39.17		3.2		2.17	$	35.68		2.6	$	35.01
	43.71	-		46.17		4.5		5.53		44.77		—		—
	46.87	-		49.55		1.9		3.97		46.89		0.6		46.87
	56.86	-		56.86		1.6		6.96		56.86		—		—

$	23.76	-	$	56.86		11.2		4.53	$	44.35		3.2	$	37.28