Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Intangible Assets
Intangible assets not subject to amortization	$ 54.5	$ 55.6
Cost of additions reduced by recognition of tax credits	1.1	2.2	$ 2.6
Capitalized cost of software under development	$ 0.4	$ 0.3	$ 0.3
Interest costs, weighted average rate	4.82%	2.48%	3.04%
Weighted average amortization period	8 years 7 months 6 days	9 years	9 years 1 month 6 days