Earnings Per Share (EPS) And Dividends (Dividend Payments On Common Stock) (Detail) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Feb. 20, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share, Diluted [Line Items]
Dividend Payments on Common Stock, Per Share		$ 1.72	$ 1.64	$ 1.56
Dividend Payments on Common Stock		$ 870	$ 830	$ 789
Subsequent Event [Member]
Earnings Per Share, Diluted [Line Items]
Common stock dividends per share	$ 0.45