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		9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings (Loss) Per Share
Net income (loss)	$ (45)	$ 142	$ 257	$ 480
Weighted Average Number of Shares Outstanding, Basic	311	311	311	312
Dilutive potential common shares related to stock award plans and from assumed exercise of stock options	0	8	7	8
Weighted Average Number of Shares Outstanding, Diluted	311	323	333	322
Basic	$ (0.14)	$ 0.46	$ 0.83	$ 1.54
Diluted	$ (0.14)	$ 0.44	$ 0.77	$ 1.49
Convertible Debt
Antidilutive Securities Excluded from Computation of Earnings (Loss) Per Share
Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants	0	4	8	2
Warrants
Antidilutive Securities Excluded from Computation of Earnings (Loss) Per Share
Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants	0	0	7	0