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Stock Options and Stock-Based Compensation (Details)	3 Months Ended
Stock Options and Stock-Based Compensation (Details)	Jun. 30, 2012	Jun. 30, 2011
Fair value of options granted
Risk-free interest rate	0.62%	1.88%
Expected volatility	47.00%	46.00%
Expected dividend yield	0.00%	0.00%
Expected forfeiture rate	11.70%	9.30%
Expected weighted average life of option in years	4 years 7 months 6 days	4 years 8 months 12 days

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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