Earnings Per Share (EPS) And Dividends (Basic And Diluted Earnings Per Share Computation) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net Income	$ 648	$ 448
Weighted Average Common Shares Outstanding, Basic (shares)	504	504
Effect of Stock Based Compensation Awards, Basic (shares)	0	0
Total Shares, Basic (shares)	504	504
Net Income, Basic (dollars per share)	$ 1.29	$ 0.89
Weighted Average Common Shares Outstanding, Diluted (shares)	504	504
Effect of Stock Based Compensation Awards, Diluted (shares)	3	3
Total Shares, Diluted (shares)	507	507
Net Income, Diluted (dollars per share)	$ 1.28	$ 0.88