Earnings Per Share (Computation Of Basic Earnings And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share Reconciliation [Abstract]
Net income (loss)	$ 204	$ 365
Weighted Average Number of Shares Outstanding, Basic	286	288
Dilutive potential common shares related to stock award plans and from assumed exercise of stock options	3	4
Weighted Average Number of Shares Outstanding, Diluted	289	292
Earnings Per Share, Basic	$ 0.71	$ 1.27
Earnings Per Share, Diluted	$ 0.71	$ 1.25