Note 12. Stock-Based Compensation Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

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

A summary of activity for the year ended December 31, 2017 is presented below (number of shares in millions):



	Restricted Stock Units			Weighted Average Grant Date Fair Value		Performance Share Units (a)			Weighted Average Grant Date Fair Value		Options (f)			Weighted Average Exercise Price
Outstanding at January 1, 2017	1.5			$	37.72	1.4			$	38.31	3.3			$	31.69
Granted	1.2			28.61		0.7			27.70		0.7			29.60
Distributed/Exercised	(0.6	)	(b)	39.64		(0.3	)	(c)	42.30		(0.3	)	(d)	23.29
Forfeited/Expired	(0.1	)		30.90		—			—		(0.1	)		50.24
Outstanding at December 31, 2017	2.0			$	31.71	1.8			$	33.16	3.6		(e)	$	31.75

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(a)	The PSU amounts in the table are shown at the target amount of the award.


(b)	The total fair value of RSUs which were distributed during the year ended December 31, 2017 was $26 million.

(c)

The total fair value of PSUs which were distributed during the year ended December 31, 2017 was $14 million, which includes the distribution of PSUs awarded in 2014, measuring performance over a three-year performance period ended December 31, 2016, at a fair value of $10 million. Amounts distributed do not include 0.2 million PSUs awarded in 2015, measuring performance over a three-year period ended and vested December 31, 2017, at a fair value of $9 million and at a weighted average grant date fair value of $46.46. These PSUs were distributed in early 2018.


(d)	The intrinsic value of options exercised during the year ended December 31, 2017 was $2 million. Cash received from options exercised during the year ended December 31, 2017 was $8 million.


(e)	Options outstanding at December 31, 2017 have an intrinsic value of $6 million and have a weighted average remaining contractual life of 5.8 years.

(f)The following table summarizes information regarding exercisable stock options as of December 31, 2017:



Range of Exercise Prices	Options Vested	Weighted Average Exercise Price		Aggregate Intrinsic Value		Weighted Average Remaining Contractual Life
$15.00 to $50.00	2.4	$	27.86	$	6.3	4.7 years
$50.01 and above	0.1	$	140.26	$	—	2.8 years

Summary of Exercisable Stock Options Activity

The following table summarizes information regarding exercisable stock options as of December 31, 2017:



Range of Exercise Prices	Options Vested	Weighted Average Exercise Price		Aggregate Intrinsic Value		Weighted Average Remaining Contractual Life
$15.00 to $50.00	2.4	$	27.86	$	6.3	4.7 years
$50.01 and above	0.1	$	140.26	$	—	2.8 years

Schedule of Market Performance Unit Award Valuation Assumptions

he fair value of the PSU RTSR award was estimated on the date of grant using the Monte Carlo Simulation method utilizing the following assumptions:



	2017 RTSR PSU			2016 RTSR PSU			2015 RTSR PSU
Weighted average grant date fair value	$	27.98		$	27.99		$	41.08
Weighted average expected volatility (a)	29.0		%	28.1		%	25.1		%
Weighted average volatility of XHB	18.4		%	19.4		%	21.1		%
Weighted average correlation coefficient	0.53			0.58			0.57
Weighted average risk-free interest rate	1.5		%	0.9		%	1.0		%
Weighted average dividend yield	—			—			—

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(a)	Expected volatility is based on historical volatilities of the Company and select comparable companies.

Summary of Stock Options Valuation Assumptions

The fair value of the options was estimated on the date of grant using the Black-Scholes option-pricing model utilizing the following assumptions:



	2017 Options			2016 Options			2015 Options
Weighted average grant date fair value	$	8.61		$	10.81		$	17.66
Weighted average expected volatility (a)	30.7		%	31.7		%	36.1		%
Weighted average expected term (years) (b)	6.25			6.25			6.25
Weighted average risk-free interest rate (c)	2.0		%	1.3		%	1.6		%
Weighted average dividend yield	1.2		%	0.1		%	—		%

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(a)	Expected volatility was based on historical volatilities of the Company and select comparable companies.


(b)	The expected term of the options granted represents the period of time that options are expected to be outstanding and is based on the simplified method.


(c)	The risk-free interest rate was based on the U.S. Treasury yield curve in effect at the time of the grant, which corresponds to the expected term of the options.