Capital Stock and Stock-Based Compensation Plans - Summary of Common Stock and Treasury Stock Activity (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary Of Common Stock Activity [Roll Forward]
Common stock balance, January 1 (in shares)	862,912,792	874,701,118	883,108,963
Common stock acquired (in shares)	(17,219,642)	(18,786,897)	(19,185,828)
Shares issued for stock options (in shares)	8,145,777	6,040,920	9,670,988
Shares issued for restricted stock and other (in shares)	862,852	957,651	1,106,995
Common stock balance, December 31 (in shares)	854,701,779	862,912,792	874,701,118
Summary Of Treasury Stock Activity [Roll Forward]
Treasury stock balance, January 1 (in shares)	602,793,568	591,005,242	582,597,397
Common stock acquired (in shares)	17,219,642	18,786,897	19,185,828
Shares issued for stock options (in shares)	(8,145,777)	(6,040,920)	(9,670,988)
Shares issued for restricted stock and other (in shares)	(862,852)	(957,651)	(1,106,995)
Treasury stock balance, December 31 (in shares)	611,004,581	602,793,568	591,005,242