Income Taxes (Reconciliation Between Effective Tax Rate On Income From Continuing Operations And Statutory Tax Rate) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Income Tax Disclosure [Abstract]
Income tax provision at federal statutory rate	$ 734	$ 670	$ 670
State and local income taxes net of federal tax benefit	57	58	56
Foreign income taxed at various rates	(166)	(136)	(174)
Canadian litigation	122	0	0
Unrecognized tax benefits and settlements	(6)	1	(18)
Tax credits	(6)	(13)	(13)
Other, net	7	1	(7)
Income tax provision	$ 742	$ 581	$ 514