Significant Non-Cash Investing Activities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Receivables from outside parties for the funding of capital expenditures	$ 34.1	$ 16.4
Purchases of property and equipment accrued in accounts payable but not yet paid	$ 26.7	$ 18.1