Financing Arrangement (Schedule Of Interest Expense Related To Notes) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Financing Arrangement [Line Items]
Amortization of debt discount	$ 0	$ 0	$ (1)
Amortization of debt issuance costs	(2)	(2)	(2)
Coupon interest expense	(43)	(42)	(41)
Interest Expense, Other	0	0	(1)
Total interest expense	$ (45)	$ (44)	$ (45)