Retirement and Deferred Compensation Plans - Schedule of Components of Net Periodic Benefit Cost and Other Amounts Recognized in Other Comprehensive Loss (Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Plan [Member]
Net Periodic Benefit Cost
Service cost	$ 15.5	$ 19.4	$ 22.0
Interest cost	21.1	8.7	6.1
Expected return on assets	(19.0)	(14.7)	(12.2)
Settlements	6.7	2.7	1.0
Net (gain) loss	(3.3)	1.8	4.6
Prior service cost	0.7	0.7	0.7
Net periodic benefit cost	21.7	18.6	22.2
Other Changes in Plan Assets and Benefit Obligation Recognized in Other Comprehensive Income/Loss
Net (gain) loss	31.9	(40.9)	(60.0)
Prior service credit	(1.2)	(0.2)
Amortization of net loss	(3.7)	(5.0)	(5.6)
Amortization of prior service cost	(0.7)	(0.7)	(0.7)
Total recognized in other comprehensive income/loss	26.3	(46.8)	(66.3)
Total recognized in net periodic benefit cost and other comprehensive income/loss	48.0	(28.2)	(44.1)
Postretirement Health Coverage [Member]
Net Periodic Benefit Cost
Interest cost	0.5	0.3	0.2
Net (gain) loss	0.0	0.2	0.2
Prior service cost	(0.8)	(0.8)	(0.8)
Net periodic benefit cost	(0.3)	(0.3)	(0.4)
Other Changes in Plan Assets and Benefit Obligation Recognized in Other Comprehensive Income/Loss
Net (gain) loss	(1.0)	(2.0)	0.2
Amortization of net loss	0.0	(0.2)	(0.2)
Amortization of prior service cost	(0.8)	(0.8)	(0.8)
Total recognized in other comprehensive income/loss	(0.2)	(1.4)	0.8
Total recognized in net periodic benefit cost and other comprehensive income/loss	$ (0.5)	$ (1.7)	$ 0.4