Acquisitions Cash Paid for Acquisitions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash Paid for Acquisitions [Abstract]
Cost of investment: current-year acquisitions	$ 5.8	$ 235.4	$ 0.0
Cost of investment: prior-year acquisitions	16.6	9.3	28.0
Less: net cash acquired	3.2	3.2	0.0
Total cost of investment	19.2	241.5	28.0
Operating payments	2.7	9.6	39.1
Total cash paid for acquisitions	21.9	251.1	67.1
Acquisitions, net of cash acquired	(2.6)
Payments for previous acquisition, financing cash flows	12.9	9.3	$ 28.0
Acquired finite-lived intangible assets related to acquisitions	$ 8.5	$ 62.0