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, 2018	Mar. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		0
Net Income (Loss)	$ 558	$ 114
Weighted Average Common Shares Outstanding, Basic (shares)	504	505
Effect of Stock Based Compensation Awards, Basic (shares)	0	0
Total Shares, Basic (shares)	504	505
Net Income, Basic (dollars per share)	$ 1.11	$ 0.23
Weighted Average Common Shares Outstanding, Diluted (shares)	504	505
Effect of Stock Based Compensation Awards, Diluted (shares)	3	3
Total Shares, Diluted (shares)	507	508
Net Income, Diluted (dollars per share)	$ 1.10	$ 0.22