Benefit Plans (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended
	Jun. 30, 2020	May 31, 2019	Mar. 31, 2021	Mar. 31, 2020
Components of net periodic benefit cost
Contributions to qualified and non qualified pension plans			$ 16.1	$ 13.7
Pension Plan [Member]
Components of net periodic benefit cost
Benefit Plan, Plan Assets, Reimbursement from CTA	$ 16.0	$ 13.5
Other Postretirement Benefits Plan [Member]
Components of net periodic benefit cost
Service cost			0.0	0.0
Interest cost			(0.2)	(0.1)
Expected return on plan assets			0.0	0.0
Recognized net actuarial loss			0.1	0.0
Other			0.0	0.0
Net periodic pension benefit cost			0.3	0.1
Domestic Plan [Member] | Pension Plan [Member]
Components of net periodic benefit cost
Service cost			0.8	1.0
Interest cost			(4.0)	(4.7)
Expected return on plan assets			(6.4)	(6.3)
Recognized net actuarial loss			2.2	1.9
Other			0.0	0.0
Net periodic pension benefit cost			0.6	1.3
Foreign Plan [Member] | Pension Plan [Member]
Components of net periodic benefit cost
Service cost			2.5	2.5
Interest cost			(0.8)	(1.0)
Expected return on plan assets			(3.8)	(3.3)
Recognized net actuarial loss			0.8	(0.1)
Other			0.0	0.1
Net periodic pension benefit cost			$ 0.3	$ 0.2