Indebtedness (Commercial Paper Narrative) (Details) (USD $)	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Debt Instrument [Line Items]
Short-term debt	$ 387,866,000	$ 0
Credit Facility [Member]
Debt Instrument [Line Items]
Revolving line of credit, maximum borrowing capacity	750,000,000
Commercial Paper [Member]
Debt Instrument [Line Items]
Revolving line of credit, maximum borrowing capacity	750,000,000
Short-term debt, terms	maturities that vary, but will generally not exceed 90 days from the date of issue
Short-term debt	$ 387,866,000	$ 0
Debt instrument, interest rate, effective percentage		0.35%
Maximum [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term debt maturity period	90 days