Stock-based Compensation and Employee Benefit Plans (Schedule of Assumptions Used in the Black-Scholes Valuation Model) (Details)	12 Months Ended
	Mar. 31, 2011	Mar. 31, 2010	Mar. 31, 2009
Employee Stock Option [Member]
Risk-free interest rate, minimum	0.30%	1.40%	1.00%
Risk-free interest rate, maximum	2.60%	3.10%	3.80%
Expected volatility, minimum	39.00%	40.00%	32.00%
Expected volatility, maximum	45.00%	48.00%	53.00%
Weighted-average volatility	42.00%	45.00%	42.00%
Expected term in years	4.2	4.2	4.3
Expected dividends	0.00%	0.00%	0.00%
Employee Stock Purchase Plan [Member]
Risk-free interest rate, minimum	0.20%	0.20%	0.50%
Risk-free interest rate, maximum	0.30%	0.40%	2.10%
Expected volatility, minimum	34.00%	35.00%	35.00%
Expected volatility, maximum	38.00%	57.00%	75.00%
Weighted-average volatility	36.00%	39.00%	66.00%
Expected term, minimum months	6	6	6
Expected term, maximum months	12	12	12
Expected dividends	0.00%	0.00%	0.00%