Earnings (Loss) Per Share Earnings (Loss) 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, 2018	Jun. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings (Loss) Per Share
Net income (loss)	$ 293	$ 644
Weighted Average Number of Shares Outstanding, Basic	306	309
Dilutive potential common shares related to stock award plans and from assumed exercise of stock options	4	4
Weighted Average Number of Shares Outstanding, Diluted	310	313
Earnings Per Share, Basic	$ 0.96	$ 2.08
Earnings Per Share, Diluted	$ 0.95	$ 2.06