Computation of Basic/Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Consolidated net income	$ 2,197	$ 1,503	$ 1,848
Denominator:
Denominator for basic earnings per common share - weighted-average common shares outstanding (in shares)	771	767	762
Effect of dilutive stock options and awards under the treasury stock method (in shares)	7	4	9
Denominator for diluted earnings per common share—weighted-average common shares outstanding plus dilutive common shares under the treasury stock method (in shares)	778	771	771
Basic earnings per common share (in dollars per share)	$ 2.85	$ 1.96	$ 2.43
Diluted earnings per common share (in dollars per share)	$ 2.82	$ 1.95	$ 2.40