Capital Stock - Authorized Common Stock Repurchase Programs (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares Issued
Balance at January 1 (in shares)	1,996,537,778
Balance at December 31 (in shares)	1,996,537,778	1,996,537,778
Treasury Shares
Balance at January 1 (in shares)	(545,537,923)
Balance at December 31 (in shares)	(561,531,524)	(545,537,923)
Class A Common Stock, no par value
Shares Issued
Balance at January 1 (in shares)	1,996,537,778	1,996,537,778	1,996,537,778
Exercise of stock options and issuance of other stock awards (in shares)	0	0	0
Balance at December 31 (in shares)	1,996,537,778	1,996,537,778	1,996,537,778
Treasury Shares
Balance at January 1 (in shares)	(545,537,923)	(508,401,694)	(468,172,237)
Shares repurchased (in shares)	(30,902,465)	(47,258,884)	(50,598,902)
Exercise of stock options and issuance of other stock awards (in shares)	14,908,864	10,122,655	10,369,445
Balance at December 31 (in shares)	(561,531,524)	(545,537,923)	(508,401,694)
Shares Outstanding
Balance at January 1 (in shares)	1,450,999,855	1,488,136,084	1,528,365,541
Shares repurchased (in shares)	(30,902,465)	(47,258,884)	(50,598,902)
Exercise of stock options and issuance of other stock awards (in shares)	14,908,864	10,122,655	10,369,445
Balance at December 31 (in shares)	1,435,006,254	1,450,999,855	1,488,136,084