Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Annual activity related to stock units consisted of (in thousands of shares):



			Number of Shares		Weighted Average Grant Date Fair Value		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value (in millions)
Time-based RSUs
	Outstanding at January 1, 2019		838		$	38.67
		Granted ^(a)	608		34.14
		Vested ^(b)	(502	)	36.00
		Forfeited	(97	)	38.73
	Outstanding and expected to vest at December 31, 2019 ^(c)		847		$	36.99	1.0	$	27
Performance-based and market-based RSUs
	Outstanding at January 1, 2019		1,169		$	35.14
		Granted ^(a)	570		34.56
		Vested ^(b)	—		—
		Forfeited	(678	)	28.79
	Outstanding at December 31, 2019		1,061		$	38.89	1.1	$	34
	Outstanding and expected to vest at December 31, 2019 ^(c)		412		$	40.61	1.5	$	13

__________

^(a)

Reflects the maximum number of stock units assuming achievement of all performance-, market- and time-vesting criteria and does not include those for non-employee directors, which are discussed separately below. The weighted-average fair value of time-based RSUs and performance-based RSUs granted in 2018 was $48.41 and $48.52, respectively, and the weighted-average fair value of time-based RSUs and performance-based and market-based RSUs granted in 2017 was $35.32 and $35.21, respectively.


^(b)	The total fair value of RSUs vested during 2019, 2018 and 2017 was $18 million, $20 million and $23 million, respectively.


^(c)	Aggregate unrecognized compensation expense related to time-based RSUs and performance-based and market-based RSUs amounted to $25 million and will be recognized over a weighted average vesting period of 1.2 years.

Summary of Share Based Compensation Shares Authorized Under Stock Option Plans by Exercise Price Range

Stock options exercised during 2019, 2018 and 2017 had intrinsic values of $1 million, $8 million and $21 million, respectively.