Interest Paid in Cash Including Payments Related to Derivative Contracts (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract]
Interest paid in cash including payments related to derivative contracts	$ 22.9	$ 21.3	$ 44.9	$ 42.5