Income Taxes (Schedule Of Differences Between Statutory Tax Rate And Effective Tax Rate) (Details)	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Income Tax Expense Reconciliation [Line Items]
Statutory federal tax expense (benefit) rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	1.00%	0.50%	0.10%
Differences between statutory rate and foreign effective tax rate	(19.30%)	(22.10%)	(22.30%)
Valuation allowance	0.00%	(51.70%)	(9.20%)
Research and development credits	(0.70%)	(0.60%)	(1.10%)
Unremitted earnings of foreign subsidiaries	2.20%	4.90%
Non-deductible stock-based compensation	2.30%	3.10%	3.50%
Other	(0.40%)	(0.90%)	(0.60%)
Effective tax expense (benefit) rate	20.10%	(31.80%)	5.40%