Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
U.S. federal income taxes (including foreign withholding taxes):
Current federal income taxes	$ 97.6	$ 168.0	$ 105.4
Deferred federal income taxes	(16.2)	(34.9)	13.2
Total federal income taxes	81.4	133.1	118.6
State and local income taxes:
Current state and local income taxes	40.4	40.4	27.4
Deferred state and local income taxes	4.3	(5.3)	(0.9)
Total state and local income taxes	44.7	35.1	26.5
Foreign income taxes:
Current foreign income taxes	148.1	137.0	127.2
Deferred foreign income taxes	17.0	13.2	(20.5)
Total foreign income taxes	165.1	150.2	106.7
Provision for income taxes	$ 291.2	$ 318.4	$ 251.8