Income Taxes - Reconciliation of Amount Computed by Applying the Federal Statutory Income Tax Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Federal statutory tax on earnings before income taxes	$ 117.9	$ 127.9	$ 72.1
State income taxes, net of federal income tax benefit	21.6	32.6	15.8
Non-deductible officer's compensation	6.1	7.6	6.4
Other	(1.1)	1.3	0.2
Income tax provision	$ 144.5	$ 169.4	$ 94.5