Stock-Based Compensation And Employee Benefit Plans (Schedule of ESPP Activity) (Details) - Employee Stock [Member] - $ / shares shares in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, Employee Stock Purchase Plans	0.7	0.5	0.6
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 29.05	$ 31.88	$ 21.57
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
ESPP Exercise Price For Shares Issued	74.70	89.46	67.56
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
ESPP Exercise Price For Shares Issued	$ 74.89	$ 107.51	$ 99.82