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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount				0
Net Income (Loss)	$ 412	$ 395	$ 1,239	$ 618
Weighted Average Common Shares Outstanding, Basic (shares)	504	505	504	505
Effect of Stock Based Compensation Awards, Basic (shares)	0	0	0	0
Total Shares, Basic (shares)	504	505	504	505
Net Income, Basic (dollars per share)	$ 0.82	$ 0.78	$ 2.46	$ 1.22
Weighted Average Common Shares Outstanding, Diluted (shares)	504	505	504	505
Effect of Stock Based Compensation Awards, Diluted (shares)	3	2	3	2
Total Shares, Diluted (shares)	507	507	507	507
Net Income, Diluted (dollars per share)	$ 0.81	$ 0.78	$ 2.44	$ 1.22