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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net Income	$ 153	$ 269	$ 853	$ 827
Weighted Average Common Shares Outstanding, Basic (shares)	504	504	504	504
Effect of Stock Based Compensation Awards, Basic (shares)	0	0	0	0
Total Shares, Basic (shares)	504	504	504	504
Net Income, Basic (dollars per share)	$ 0.30	$ 0.53	$ 1.69	$ 1.64
Weighted Average Common Shares Outstanding, Diluted (shares)	504	504	504	504
Effect of Stock Based Compensation Awards, Diluted (shares)	3	3	3	3
Total Shares, Diluted (shares)	507	507	507	507
Net Income, Diluted (dollars per share)	$ 0.30	$ 0.53	$ 1.68	$ 1.63