Post Employment Plans - Net periodic pension cost (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Dec. 31, 2015		Dec. 31, 2017	Dec. 31, 2016	Jun. 27, 2015	[1]
Pension plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs	$ 2.2		$ 4.5	$ 4.1	$ 0.9
Interest cost	1.7		3.3	3.6	2.4
Expected return on assets	(1.8)		(4.3)	(3.9)	(2.7)
Curtailment	0.0		(0.7)	0.0	0.0
Net actuarial loss	0.4		0.8	0.5	1.0
Net periodic pension cost	2.5		3.6	4.3	1.6
Other Postretirement Benefits Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs	0.3	[1]	0.6	0.6	0.3
Interest cost	0.1	[1]	0.2	0.2	0.2
Expected return on assets	0.0		0.0	0.0	0.0
Curtailment	0.0		0.0	0.0	0.0
Net actuarial loss	0.0		(0.1)	0.0	0.1
Net periodic pension cost	$ 0.4		$ 0.7	$ 0.8	$ 0.6

[1] Includes Omega activity from March 30, 2015 to June 27, 2015