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		9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share Reconciliation [Abstract]
Net income (loss)	$ 211	$ 346	$ 761	$ 2,621
Weighted Average Number of Shares Outstanding, Basic	290	292	289	294
Dilutive potential common shares related to stock award plans and from assumed exercise of stock options	2	2	3	2
Weighted Average Number of Shares Outstanding, Diluted	292	294	292	296
Earnings Per Share, Basic	$ 0.73	$ 1.18	$ 2.63	$ 8.91
Earnings Per Share, Diluted	$ 0.72	$ 1.18	$ 2.61	$ 8.85