Capital Stock (Tables)

6 Months Ended

Jun. 30, 2020

Capital [Abstract]

Summary of Cash Dividend Activity

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

Declaration Date	Record Date	Payment Date	Cash Dividend per Share	Total
Six Months Ended June 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
Six Months Ended June 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

Summary of Share Repurchases

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

	Six Months Ended June 30
	2020		2019
Shares repurchased	2.1		2.8
Average price per share	$	273.72	$	273.84
Aggregate cost	$	584	$	752
Authorization remaining at the end of the period	$	3,208	$	4,741

Summary of Stock Option Activity

A summary of stock option activity for the six months ended June 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		271.33
Exercised	(0.5	)	118.84
Forfeited or expired	(0.1	)	267.09
Outstanding at June 30, 2020	3.5		221.84		7.08	$	182
Exercisable at June 30, 2020	1.9		176.59		5.51	$	175

Summary of Nonvested Restricted Stock Activity Including Restricted Stock Units

A summary of the nonvested restricted stock activity, including restricted stock units, for the six months ended June 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		272.14
Vested	(1.2	)	193.36
Forfeited	(0.1	)	269.70
Nonvested at June 30, 2020	1.4		271.77

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 six months ended June 30, 2020 and 2019:

	Six Months Ended June 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 six months ended June 30, 2020 and 2019: 

	Six Months Ended June 30
	2020		2019
Options granted during the period	$	54.04	$	68.80
Restricted stock awards granted during the period	272.14		307.08