Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 01, 2014	Aug. 05, 2014	Mar. 20, 2014
Related Party Transaction [Line Items]
Management Fee	$ 0	$ 2.5	$ 5.0
Net proceeds used for termination of Management Services Agreement		24.4
Senior notes due 2019 [Member]
Related Party Transaction [Line Items]
Debt Instrument, Repurchased Face Amount				$ 541.4	$ 234.7	$ 25.0