Nature of Operations and Significant Accounting Policies (Reclassified Out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax impact	$ (161.9)	$ (67.4)	$ (43.4)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total before tax	14.0	22.2	17.7
Tax impact	3.5	4.2	3.9
Total reclassifications for the period	10.5	18.0	13.8
Pension Plan
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service costs	(0.1)	(0.1)	(0.3)
Net loss	15.2	23.4	19.1
Postretirement Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service costs	(1.1)	(1.1)	(1.1)
Net loss	$ 0.0	$ 0.0	$ 0.0