Pension Benefits (Schedule Of Sensitivity To Changes In Weighted-Average Discount Rate For U.S. Pension Plans) (Details) (Defined Pension Benefit Plans [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2012
Defined Pension Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
One percentage point increase on projected benefit obligation	$ (38)
One percentage point decrease on projected benefit obligation	44
One percentage point increase on net periodic pension cost	(2)
One percentage point decrease on net periodic pension cost	$ 3