Derivative Instruments and Hedging Activities - Gains (Losses) Recorded In OCI For the Effective Portion of Our Designated Cash Flow Hedges (Details) - Designated derivatives - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Jun. 27, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recorded in OCI (Effective Portion)	$ 1.4	$ 9.4	$ (6.9)	$ (20.5)
Treasury locks
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recorded in OCI (Effective Portion)	0.0	0.0	0.0	(2.7)
Interest rate swap agreements
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recorded in OCI (Effective Portion)	(0.3)	0.0	(9.0)	(10.1)
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recorded in OCI (Effective Portion)	$ 1.7	$ 9.4	$ 2.1	$ (7.7)