Employee Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of net periodic benefit cost
Pension settlement	$ 99.2	$ 0.4	$ 0.0
Pension Benefits [Member]
Components of net periodic benefit cost
Service cost	4.9	5.3	5.0
Interest cost	10.2	12.3	12.6
Expected return on plan assets	(13.4)	(18.8)	(21.3)
Amortization of prior service cost	0.1	0.1	0.2
Amortization of net loss	5.6	9.2	8.1
Settlements or curtailments	99.2	0.4	0.0
Other	(0.5)	0.3	0.7
Total net periodic benefit cost	$ 106.1	$ 8.8	$ 5.3