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		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share Reconciliation [Abstract]
Net income (loss)	$ 185	$ 854	$ 550	$ 2,275
Weighted Average Number of Shares Outstanding, Basic	289	295	289	296
Dilutive potential common shares related to stock award plans and from assumed exercise of stock options	4	1	3	1
Weighted Average Number of Shares Outstanding, Diluted	293	296	292	297
Earnings Per Share, Basic	$ 0.64	$ 2.89	$ 1.90	$ 7.69
Earnings Per Share, Diluted	$ 0.63	$ 2.89	$ 1.88	$ 7.66