Income Taxes (Schedule Of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits, beginning balance	$ 389	$ 331	$ 254
Increases in unrecognized tax benefits related to prior year tax positions	10	3	33
Decreases in unrecognized tax benefits related to prior year tax positions	(12)	(3)	(4)
Increases in unrecognized tax benefits related to current year tax positions	75	64	63
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(7)	0	(10)
Reductions in unrecognized tax benefits due to lapse of applicable statute of limitations	(2)	(3)	(4)
Changes in unrecognized tax benefits due to foreign currency translation	4	(3)	(1)
Unrecognized tax benefits, ending balance	$ 457	$ 389	$ 331