Long-Term Debt Senior Notes due 2015 (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			3 Months Ended		9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Mar. 31, 2014	Sep. 30, 2014	Dec. 01, 2014	Aug. 05, 2014	Mar. 20, 2014
Debt Instrument [Line Items]
Debt, long-term and short-term	$ 3,192.4			$ 3,192.4
Proceeds from issuance of long-term debt	1,175.0	1,535.2	135.7
Gains (Losses) on Extinguishment of Debt	90.7	64.0	17.2
Write off of Deferred Debt Issuance Cost	12.6	20.1
Deferred financing costs, net	33.0	30.1	53.2	33.0
Senior notes due 2019 [Member]
Debt Instrument [Line Items]
Long-term debt, stated interest rate	8.50%			8.50%
Debt, long-term and short-term	503.9	1,305.0		503.9
Senior Notes, Amount Repurchased							541.4	234.7	25.0
Extinguishment of Debt, Fees Paid to Lenders	23.0			10.0	2.4
Extinguishment of Debt, Accrued Interest Paid to Lenders									1.0
Gains (Losses) on Extinguishment of Debt	(36.9)			(22.1)		(2.7)
Write off of Deferred Debt Issuance Cost	$ 4.7			$ 2.2	$ 0.3