Share-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

A summary of stock option activity is as follows:

	Shares (000)	Wtd. Avg. Exercise Price Per Share	Wtd. Avg. Remaining Contractual Term (years)	Aggregate Intrinsic Value (in millions)
Outstanding, January 1, 2018	574	$77
Granted	122	123
Exercised	(24)	78		$1
Expired or cancelled	—	—
Outstanding, December 31, 2018	672	$85	5.9	$1
Exercisable, December 31, 2018	401	$76	4.5	$1
Outstanding, January 1, 2019	672	$85
Granted	174	84
Exercised	(79)	65		$2
Expired or cancelled	(44)	91
Outstanding, December 31, 2019	723	$87	6.1	$10
Exercisable, December 31, 2019	426	$82	4.5	$8
Outstanding, January 1, 2020	723	$87
Granted	156	93
Exercised	(90)	59		$3
Expired or cancelled	(1)	54
Outstanding, December 31, 2020	788	$91	6.2	$4
Exercisable, December 31, 2020	455	$90	4.5	$3

Schedule of Options Outstanding and Exercisable

Options outstanding and exercisable as of December 31, 2020 were as follows:

	Options Outstanding			Options Exercisable
Exercise Price	Shares (000)	Weighted- Average Remaining Contractual Life (years)	Weighted- Average Exercise Price	Shares (000)	Weighted- Average Exercise Price
$75-$79	208	4.3	$76	208	$76
$80-$89	180	7.5	84	65	84
$90-$99	287	7.1	95	108	97
$100-$123	113	5.2	123	74	123
	788	6.2	$91	455	$90

Assumptions Used to Estimate Fair Value of Share Awards

We estimated the fair value of each stock option on the date of grant using the Black-Scholes option pricing model and the following assumptions:

Year Ended December 31	2020			2019			2018
Average risk-free interest rate		1.5	%		2.5	%		2.6	%
Expected dividend yield		2.5	%		2.9	%		1.6	%
Expected volatility		27.0	%		27.0	%		27.0	%
Expected term (years)		6.0			6.0			6.0

Summary of Restricted Stock Activity

A summary of restricted stock activity is as follows:

	Shares (000)	Wtd. Avg. Price Per Share	Wtd. Avg. Remaining Contractual Term (years)	Aggregate Intrinsic Value (in millions)
Unvested, January 1, 2018	448	$77	1.2
Granted	145	119
Vested	(174)	77
Forfeited	(23)	89
Unvested, December 31, 2018	396	$92	1.3
Granted	236	$84
Vested	(150)	76
Forfeited	(36)	93
Unvested, December 31, 2019	446	$97	1.5
Granted	200	$92
Vested	(145)	95
Forfeited	(17)	93
Unvested, December 31, 2020	484	$94	1.4	$44

Performance Share Units

A summary of the performance share units detail by grant year is as follows:

	2017		2018		2019		2020
Grant Date(s)	February 9, 2017		February 15, 2018		February 15, 2019		February 14, 2020
Performance Period (years)	2017-2019		2018-2020		2019-2021		2020-2022
Vesting Date	February 2020(a)		February 2021(a)		February 2022(a)		February 2023(a)
Payout Levels (in units):
Threshold Award		57,563		42,361		61,381		59,698
Target Award		115,125		84,726		122,761		119,395
Outstanding Award		230,250		169,452		245,522		238,790
Shares Issued in 2020		88,807		—		—		—
Payout Achieved Over Performance Period		—		42,361		—		—

(a) 2018, 2019 and 2020 awards are scheduled to vest in February 2021, 2022 and 2023, respectively, when the Executive Compensation and Human Resources Committee of the Board of Directors determines the achievement of the performance criteria.