Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Taxes calculated at federal rate	$ 57.6	$ 68.4	$ 344.7
State taxes, net of federal benefit	(6.4)	(5.3)	48.0
Change in liability for tax positions	10.7	(0.8)	0.0
Foreign income taxed at different rates	9.5	2.1	1.8
Unremitted foreign earnings	1.2	0.0	1.0
Federal tax credits	17.3	0.0	0.0
Valuation allowance	7.7	0.0	0.0
Other items, net	(4.1)	(4.0)	(3.3)
Income tax	$ 58.9	$ 60.4	$ 392.2
Federal income tax rates	21.00%	21.00%	21.00%
State taxes, net of federal benefit	(2.30%)	(1.50%)	2.90%
Change in liability for tax positions	3.90%	(0.30%)	0.00%
Foreign income taxed at different rates	3.50%	0.60%	0.10%
Unremitted foreign earnings	0.40%	0.00%	0.10%
Federal tax credits	(6.30%)	0.00%	0.00%
Valuation allowance	2.80%	0.00%	0.00%
Other items, net	(1.50%)	(1.10%)	(0.20%)
Income tax	21.50%	18.70%	23.90%