Income Taxes, Unrecognized tax benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Taxes
Unrecognized tax benefits, anticipated adjustment for changing facts and circumstances, over the next twelve month period	$ 35.4
Amount for unrecognized tax benefits, including penalties and interest, which if recognized would impact the effective tax rate	208.6	$ 194.4
Reconciliation of the gross amounts of unrecognized tax benefits
Unrecognized tax benefits as of January 1	164.1	147.7	$ 135.3
Gross increases for tax positions in prior periods	3.8	12.8	6.5
Gross increases for tax positions in current period	8.4	4.9	8.2
Settlements	(1.0)	(0.4)	0.0
Lapse of statute of limitations	(1.1)	(0.9)	(2.3)
Unrecognized tax benefits at the end of the period	174.2	164.1	147.7
Estimated interest and penalties included in provision for income taxes	5.8	0.8	(4.6)
Tax-related interest and penalties liability for unrecognized tax benefits	$ 41.8	$ 35.8	$ 34.5