Stock Option Plans (Tables)

12 Months Ended

Dec. 31, 2014

Black-Scholes Option Pricing Model with Weighted Average

For purposes of expense recognition in 2014, 2013 and 2012, 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:


	Year Ended December 31,
	2014			2013			2012
Expected dividend yield		3.0	%		3.5	%		4.0	%
Expected risk-free interest rate		1.8	%		1.2	%		1.2	%
Volatility		28.9	%		29.6	%		26.9	%
Expected life (in years)		5.5			6.0			5.0

Stock Option Activity and Related Information

The following is a summary of our stock option activity and related information for 2014, 2013 and 2012 (in millions, except exercise price and year data):


Year Ended December 31, 2014	Shares Under Option			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Beginning balance		8.3		$	31.35
Granted		1.9			46.86
Exercised		(1.7	)		28.80
Forfeited or canceled		(0.1	)		28.36

Ending balance		8.4		$	35.49		3.96	$	97.2

Exercisable at end of year		2.6		$	26.91		1.87	$	52.8

Ending vested and expected to vest		8.3		$	35.38		3.93	$	96.6

Year Ended December 31, 2013
Beginning balance		9.0		$	28.80
Granted		1.7			39.17
Exercised		(2.3	)		27.11
Forfeited or canceled		(0.1	)		26.01

Ending balance		8.3		$	31.35		3.62	$	129.4

Exercisable at end of year		3.8		$	27.64		2.15	$	72.5

Ending vested and expected to vest		8.2		$	31.28		3.59	$	128.3

Year Ended December 31, 2012
Beginning balance		10.6		$	27.20
Granted		1.4			35.71
Exercised		(2.8	)		26.14
Forfeited or canceled		(0.2	)		29.46

Ending balance		9.0		$	28.80		3.41	$	53.9

Exercisable at end of year		5.1		$	27.50		2.52	$	36.3

Ending vested and expected to vest		8.9		$	28.76		3.39	$	53.8

Other Information Regarding Stock Options Outstanding and Exercisable

Other information regarding stock options outstanding and exercisable at December 31, 2014 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
$	21.28 - $ 27.25		2.3		1.59	$	25.78		1.9	$	25.76
	27.35 - 35.71		2.5		3.59		33.18		0.7		29.83
	35.95 - 46.16		1.7		5.20		39.19		—		—
	46.87 - 46.87		1.9		6.19		46.87		—		—

$	21.28 - $ 46.87		8.4		3.96	$	35.49		2.6	$	26.91