Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Revenue from External Customer [Line Items]
Marketing expense	$ (18.1)	$ (19.6)
Property, office, and technology expense	(117.6)	(110.5)
General and administrative expense	138.5	105.0
Reclassification Adjustments [Member]
Revenue from External Customer [Line Items]
Marketing expense	6.7	5.4
Property, office, and technology expense	23.6	23.9
General and administrative expense	$ 30.3	$ 29.3