Share-Based Compensation (Schedule Of Weighted-Average Assumptions Used To Estimate The Fair Value Of Employee Stock Options) (Details)	12 Months Ended
Mar. 31, 2012 Y	Mar. 31, 2011 Y	Mar. 31, 2010 Y
Share-Based Compensation [Abstract]
Expected stock price volatility	27.00%	29.00%	33.00%
Expected dividend yield	1.00%	1.10%	0.70%
Risk-free interest rate	2.00%	3.00%	2.00%
Expected life (in years)	5	5	5

The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

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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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