Benefit Plans and Other Postretirement Benefits, Defined benefit plans (Details) - Pension Benefits - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Jan. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Components of net pension expense:
Service cost		$ 1.8	$ 1.9
Interest cost		5.4	4.9
Expected return on plan assets		(9.2)	(9.7)
Amortization of prior service cost		0.4	0.6
Amortization of net actuarial losses		4.6	5.9
Net pension expense		$ 3.0	$ 3.6
United States
Defined Benefit Plan Disclosure
Employer contributions	$ 81.0