Long-term Employee Benefits - Schedule of Net Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net periodic benefit cost:
Service cost	$ 1.8	$ 2.2	$ 5.4	$ 6.7
Interest cost	3.2	3.2	9.8	10.0
Expected return on plan assets	(3.4)	(3.9)	(10.4)	(12.2)
Amortization of actuarial loss, net	0.5	0.3	1.4	0.9
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0.0	0.0	0.0	(0.1)
Net periodic benefit (gain) cost	$ 2.1	$ 1.8	$ 6.2	$ 5.3