Capital Stock (Tables)

9 Months Ended

Sep. 30, 2018

Capital [Abstract]

Summary of Cash Dividend Activity

A summary of the cash dividend activity for the nine months ended September 30, 2018 and 2017 is as follows:

Declaration Date	Record Date	Payment Date	Cash Dividend per Share	Total
Nine Months Ended September 30, 2018
January 30, 2018	March 9, 2018	March 23, 2018	$0.75	$	192
April 24, 2018	June 8, 2018	June 25, 2018	$0.75	$	196
July 24, 2018	September 10, 2018	September 25, 2018	$0.75	$	195
Nine Months Ended September 30, 2017
February 22, 2017	March 10, 2017	March 24, 2017	$0.65	$	172
April 27, 2017	June 9, 2017	June 23, 2017	$0.65	$	172
July 25, 2017	September 8, 2017	September 25, 2017	$0.70	$	181

Summary of Share Repurchases

A summary of common stock repurchases from October 1, 2018 through October 18, 2018 (subsequent to September 30, 2018) and for the nine months ended September 30, 2018 and 2017 is as follows:

	October 1, 2018   Through   October 18, 2018		Nine Months Ended September 30
			2018		2017
Shares repurchased	0.3		5.0		8.7
Average price per share	$	274.32	$	240.15	$	186.80
Aggregate cost	$	95	$	1,192	$	1,635
Authorization remaining at the end of the period	$	5,891	$	5,986	$	2,541

Summary of Stock Option Activity

A summary of stock option activity for the nine months ended September 30, 2018 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, 2018	4.3		$	124.31
Granted	0.9		232.61
Exercised	(1.0	)	110.85
Forfeited or expired	(0.2	)	187.56
Outstanding at September 30, 2018	4.0		148.58		6.42	$	498
Exercisable at September 30, 2018	2.6		125.25		5.27	$	393

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, 2018 is as follows:

	Restricted Stock Shares and Units		Weighted- Average Grant Date Fair Value per Share
Nonvested at January 1, 2018	2.0		$	152.20
Granted	0.9		233.27
Vested	(1.0	)	147.92
Forfeited	(0.1	)	186.38
Nonvested at September 30, 2018	1.8		182.57

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, 2018 and 2017:

	Nine Months Ended September 30
	2018		2017
Risk-free interest rate	2.90	%	2.31	%
Volatility factor	30.00	%	32.00	%
Quarterly dividend yield	0.323	%	0.397	%
Weighted-average expected life (years)	3.70		4.00

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, 2018 and 2017:

	Nine Months Ended September 30
	2018		2017
Options granted during the period	$	55.44	$	40.84
Restricted stock awards granted during the period	233.27		173.62