Share-based Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2017

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

Weighted Average Black-Scholes Assumptions

Based on the results of the model, the weighted-average grant date fair value of stock options granted for 2017, 2016, and 2015 were $44.01, $31.21 and $63.40, respectively, using the following assumptions:

Weighted Average Black-Scholes Assumptions	2017		2016		2015
Risk-free interest rate	1.9	%	1.2	%	1.5	%
Expected volatility	32.0	%	33.5	%	35.5	%
Expected dividend yield	2.3	%	2.8	%	1.4	%
Expected option life, in years	5		5		5

Summary of Stock Option Activity

The following table summarizes stock option activity during 2017:

In thousands, except per share data	Number of Options		Weighted- Average Exercise Price
Outstanding at January 1	2,216		$	112.00
Granted	427		177.15
Exercised	(311	)	108.80
Canceled or expired	(67	)	160.68
Outstanding at December 31	2,265		$	123.27
Exercisable at December 31	1,463		$	102.01

Summary of Additional Information Related to Stock Options Outstanding

The table below summarizes additional information related to stock options outstanding at December 31, 2017:

Options in thousands / dollars in millions, except share data	Outstanding Net of Expected Forfeitures		Options Exercisable
Number of options	2,163		1,463
Weighted-average exercise price per share	$	123.19	$	102.01
Aggregate intrinsic value	$	112	$	106
Weighted-average remaining contractual term, in years	6		4

Summary of Stock Unity Activity

The following table summarizes stock unit activity during 2017:

Stock units in thousands, except per-share data	Number of Stock Units		Weighted- Average Grant Date Fair Value
Non-vested, at January 1	815		$	134.21
Granted	307		164.26
Canceled	(57	)	158.94
Vested and transferred to unrestricted	(286	)	123.95
Non-vested, at December 31	779		$	155.17