Benefit Plans (Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Contributions by employer			$ 7.5	$ 7.5
Pension [Member]
Service cost	$ 0.5	$ 0.6	1.1	1.2
Interest cost	3.7	3.7	7.3	7.4
Expected return on assets	(4.0)	(3.7)	(7.9)	(7.4)
Prior service cost	0.3	0.2	0.5	0.5
Actuarial loss / (gain)	0.8	0.6	1.6	1.1
Net periodic benefit cost	$ 1.3	$ 1.4	$ 2.6	$ 2.8