Stock Plans (Tables)

12 Months Ended

Dec. 31, 2017

Table Text Block [Abstract]

Summary of Stock Option and RSA Activity

A summary of stock option and RSA/RSU activity as of December 31, 2017, and changes during the year, is presented below:

	Stock Options			RSAs/RSUs
(Shares in thousands)	Shares	Weighted-Average Exercise Price		Shares	Weighted-AverageGrantPrice
Outstanding as of December 31, 2016	10,272	$	47.68	7,500	$	69.22
Granted	869		87.19	2,670		77.80
Exercised/vested	(3,766)		34.48	(2,335)		75.85
Forfeited	(102)		67.57	(620)		68.80
Expired	(11)		86.11	―		―
Outstanding as of December 31, 2017	7,262		58.92	7,215	$	70.29
Options vested and expected to vest as of December 31, 2017	7,194		58.86
Options exercisable as of December 31, 2017	3,399	$	45.93

Weighted-average remaining contractual life and aggregate intrinsic value of the Company's stock options outstanding, exerciseable, and vested and expected to vest

The weighted-average remaining contractual life and the aggregate intrinsic value (the amount by which the fair value of the Company’s stock exceeds the exercise price of the option) of the stock options outstanding, exercisable, vested, and expected to vest as of December 31, 2017, were as follows:

	Outstanding		Exercisable		Vested and Expected to Vest
Weighted-average remaining contractual life (in years)		5.8		3.1		5.7
Aggregate intrinsic value (millions)	$	293	$	181	$	291

Weighted Average Assumptions Used

The fair value of each option is estimated on the date of grant using a Black-Scholes-Merton option-pricing model. The following weighted-average assumptions were used for options granted in 2017, 2016 and 2015:

	2017			2016			2015
Dividend yield		1.8	%		1.9	%		1.1	%
Expected volatility(a)		24	%		25	%		37	%
Risk-free interest rate		2.3	%		1.5	%		1.7	%
Expected life of stock option (in years)(b)		6.9			6.3			6.7
Weighted-average fair value per option	$	18.18		$	13.67		$	29.20

• The expected volatility is based on both weighted historical and implied volatilities of the Company’s common stock price.
• The expected life of stock options was determined using both historical data and expectations of option exercise behavior.

Special Stock Option Assumptions [Text Block]

On October 31, 2017, certain senior executives were awarded stock options with a term of seven years, and include a three-year service condition, as well as performance and market conditions. Therefore, the fair values of these options were estimated at the grant date using a Monte Carlo Valuation model with the following assumptions:

	October 31, 2017
Dividend yield		1.58	%
Expected volatility(a)		21.41	%
Risk-free interest rate		2.26	%
Expected life of stock option (in years)		7
Fair value per option	$	19.18

The expected volatility is based on both weighted historical and implied volatilities of the Company’s common stock price.

Summary of Stock Plan Expenses

The components of the Company’s total stock-based compensation expense (net of forfeitures) for the years ended December 31 are as follows:

(Millions)	2017		2016		2015
Restricted stock awards(a)	$	170	$	178	$	190
Stock options(a)		21		14		12
Liability-based awards		92		60		32
Total stock-based compensation expense (b)	$	283	$	252	$	234

• As of December 31, 2017, the total unrecognized compensation cost related to unvested RSAs/RSUs and options of $178 million and $21 million, respectively, will be recognized ratably over the weighted-average remaining vesting period of 2.1 years.
• The total income tax benefit recognized in the Consolidated Statements of Income for stock-based compensation arrangements for the years ended December 31, 2017, 2016 and 2015 was $102 million, $89 million and $83 million, respectively.