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Stock-Based Compensation (Schedule Of Assumptions Used In The Black-Scholes Valuation Model) (Details)
3 Months Ended 9 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2011
Dec. 31, 2010
Employee Stock Option [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Risk-free interest rate, minimum 0.40% 1.20% 0.40% 0.80%
Risk-free interest rate, maximum 1.20% 2.60% 1.80% 2.60%
Expected volatility, minimum 42.00% 41.00% 40.00% 41.00%
Expected volatility, maximum 46.00% 43.00% 46.00% 45.00%
Weighted-average volatility 45.00% 42.00% 43.00% 43.00%
Expected term (in years) 4.1 4.2 4.4 4.4
Expected dividends 0.00% 0.00% 0.00% 0.00%
Employee Stock Purchase Plan [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Risk-free interest rate, minimum       0.20%
Risk-free interest rate, maximum       0.30%
Risk-free interest rate     0.10%  
Expected volatility, minimum     39.00%  
Expected volatility, maximum     40.00%  
Expected volatility       38.00%
Weighted-average volatility     39.00% 38.00%
Expected term, minimum months     6 6
Expected term, maximum months     12 12
Expected dividends     0.00% 0.00%