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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net Income	$ 187	$ 345	$ 658	$ 931
Weighted Average Common Shares Outstanding, Basic (shares)	505	506	505	506
Effect of Stock Based Compensation Awards, Basic (shares)	0	0	0	0
Total Shares, Basic (shares)	505	506	505	506
Net Income, Basic (in dollars per share)	$ 0.37	$ 0.68	$ 1.30	$ 1.84
Weighted Average Common Shares Outstanding, Diluted (shares)	505	506	505	506
Effect of Stock Based Compensation Awards, Diluted (shares)	3	2	3	2
Total Shares, Diluted (shares)	508	508	508	508
Net Income, Diluted (in dollars per share)	$ 0.37	$ 0.68	$ 1.30	$ 1.83