Interest Expense (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Interest Expense [Abstract]
Interest on borrowings	$ 238.3	$ 150.6	$ 112.2
Fees on financing agreements	10.6	15.4	32.1
Interest on tax liabilities	3.5	12.9	1.4
Interest Costs Capitalized	(74.2)	(26.7)	(10.4)
Interest expense	178.2	152.2	135.3
Accelerated amortization of debt issuance costs			$ 15.2