Stock-Based Compensation (ESPP Purchase Option Assumptions) (Details) (Employee Stock Purchase Plan [Member])	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Valuation Assumption [Line Items]
Expected volatility	23.20%	24.70%	41.80%
Expected dividend yield	2.19%	2.38%	1.01%
Risk-free interest rate	0.10%	0.10%	0.20%
Minimum [Member]
Valuation Assumption [Line Items]
Expected term, months	3 months	3 months	3 months
Maximum [Member]
Valuation Assumption [Line Items]
Expected term, months	6 months	6 months	9 months