Computation of Basic/Diluted Earnings Per Common Share - Computation EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Consolidated net income	$ 580	$ 505	$ 328	$ 447	$ 1,084	$ 774
Denominator:
Denominator for basic earnings per common share - weighted-average common shares outstanding (in shares)	771		766		770	765
Employee stock options and awards (in shares)	5		4		5	5
Denominator for diluted earnings per common share - weighted-average common shares outstanding plus dilutive common shares under treasury stock method (in shares)	776		770		775	770
Basic earnings per common share (in dollars per share)	$ 0.75		$ 0.43		$ 1.41	$ 1.01
Diluted earnings per common share (in dollars per share)	$ 0.75		$ 0.43		$ 1.40	$ 1.01