Computation of Basic/Diluted Earnings Per Common Share - Computation EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Consolidated net income	$ 447	$ 500
Denominator:
Denominator for basic earnings per common share - weighted-average common shares outstanding (in shares)	764	759
Employee stock options and awards (in shares)	6	11
Denominator for diluted earnings per common share - weighted-average common shares outstanding plus dilutive common shares under treasury stock method (in shares)	770	770
Basic earnings per common share (in dollars per share)	$ 0.58	$ 0.66
Diluted earnings per common share (in dollars per share)	$ 0.58	$ 0.65