Capital Stock (Tables)

9 Months Ended

Sep. 30, 2020

Capital [Abstract]

Summary of Cash Dividend Activity

A summary of our cash dividend activity for the nine months ended September 30, 2020 and 2019 is as follows: 

Declaration Date	Record Date	Payment Date	Cash Dividend per Share	Total
Nine Months Ended September 30, 2020
January 28, 2020	March 16, 2020	March 27, 2020	$0.95	$	240
April 28, 2020	June 10, 2020	June 25, 2020	$0.95	$	242
July 28, 2020	September 10, 2020	September 25, 2020	$0.95	$	238
Nine Months Ended September 30, 2019
January 29, 2019	March 18, 2019	March 29, 2019	$0.80	$	206
April 23, 2019	June 10, 2019	June 25, 2019	$0.80	$	206
July 23, 2019	September 10, 2019	September 25, 2019	$0.80	$	204

Summary of Share Repurchases

A summary of common stock repurchases for the nine months ended September 30, 2020 and 2019 is as follows:

	Nine Months Ended September 30
	2020		2019
Shares repurchased	5.0		5.2
Average price per share	$	269.15	$	270.42
Aggregate cost	$	1,342	$	1,396
Authorization remaining at the end of the period	$	2,450	$	4,098

Summary of Stock Option Activity

A summary of stock option activity for the nine months ended September 30, 2020 is as follows:

	Number of Shares	Weighted- Average Option Price per Share		Weighted- Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
Outstanding at January 1, 2020	3.1	$	190.31
Granted	1.0	271.32
Exercised	(0.6)	123.36
Forfeited or expired	(0.1)	271.54
Outstanding at September 30, 2020	3.4	223.68		6.84	$	180
Exercisable at September 30, 2020	1.9	181.32		5.41	$	176

Summary of Nonvested Restricted Stock Activity Including Restricted Stock Units

A summary of the nonvested restricted stock activity, including restricted stock units, for the nine months ended September 30, 2020 is as follows:

	Restricted Stock Shares and Units	Weighted- Average Grant Date Fair Value per Share
Nonvested at January 1, 2020	1.4	$	242.47
Granted	1.3	272.11
Vested	(1.2)	194.30
Forfeited	(0.1)	271.24
Nonvested at September 30, 2020	1.4	272.04

Summary of Weighted-Average Assumptions Used to Estimate the Fair Value of Options Granted During the Periods

The following weighted-average assumptions were used to estimate the fair values of options granted during the nine months ended September 30, 2020 and 2019:

	Nine Months Ended September 30
	2020		2019
Risk-free interest rate	1.30	%	2.69	%
Volatility factor	26.00	%	25.00	%
Quarterly dividend yield	0.350	%	0.260	%
Weighted-average expected life (years)	4.30		4.40

Schedule of Weighted-Average Fair Values Determined for the Periods

The following weighted-average fair values per option or share were determined for the nine months ended September 30, 2020 and 2019: 

	Nine Months Ended September 30
	2020		2019
Options granted during the period	$	54.02	$	68.69
Restricted stock awards granted during the period	272.11		306.13