Interest And Other Expense, Net (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Interest And Other Expense, Net [Abstract]
Interest income	$ 21.9	$ 14.0	$ 32.2
Interest expense	70.6	96.1	158.1
Gains on foreign exchange transactions	39.6	33.1
Loss on foreign exchange transactions			$ 11.9