Derivative Financial Instruments - Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location (Details) - Interest Rate Contract [Member] - Cash Flow Hedging [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of (Gain) Loss Recognized in OCI on Derivatives (Effective Portion)	$ 3.5	$ (4.0)	$ 8.0	$ 1.0
Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of (Gain) Loss Reclassified from Accumulated OCI to Income (Effective Portion)	1.7	1.7	4.9	4.9
Amount of (Gain) Loss Recognized in Income on Derivatives (Ineffective Portion)	$ 1.0	$ (0.9)	$ 2.4	$ (0.2)