Derivative Financial Instruments - Schedule of Gain or Loss on the Hedged Items (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on hedged items	$ (9.0)	$ 0.0	$ 0.0
Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on hedged items	8.7	0.0	0.0
Interest rate swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on hedged items	(9.0)	0.0	0.0
Interest rate swap contracts | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on hedged items	$ 8.7	$ 0.0	$ 0.0