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Share-Based Payment (Weighted Average Assumptions for Fair Value of Stock Options) (Details)	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Weighted average assumptions for stock option awards
Risk free interest rate	1.06%	0.97%
Expected dividend yield	0.00%	0.00%
Expected stock price volatility	65.70%	62.30%
Average expected life (in years)	5 years 11 months 27 days	6 years 0 months 7 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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