Income Taxes - Income Taxes Reconciliation (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Statutory Federal Tax Rate	$ 491.3	$ 558.5	$ 307.6
Income Tax Expense (Benefit), Effective Income Tax Rate Reconciliation, Amount [Abstract]
Tax Credits	(7.2)	(8.9)	(4.4)
Investment Tax Credits, net	(15.5)	(17.9)	(37.5)
Nontaxable or Nondeductible Tax Benefits	1.0
Nontaxable or Nondeductible Tax Benefits		(7.0)	(3.0)
Effects of Cross-Border Tax Laws	13.6	10.1	10.9
Valuation Allowance	59.8	36.7	25.8
Other, net	0.8	(11.5)	(4.5)
Domestic State and Local Income Taxes, net	38.8	65.1	34.9
Foreign Tax Effects	21.1	5.5	7.7
Worldwide Changes in Unrecognized Tax Benefits	(1.1)	(2.2)	20.0
Grand Total	$ 602.6	$ 628.4	$ 357.5
Statutory Federal Tax Rate	21.00%	21.00%	21.00%
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Tax Credits	(0.30%)	(0.30%)	(0.30%)
Investment Tax Credits, net	(0.70%)	(0.70%)	(2.60%)
Nontaxable or Nondeductible Tax Benefits	0.00%
Nontaxable or Nondeductible Tax Benefits		(0.30%)	(0.20%)
Effects of Cross-Border Tax Laws	0.60%	0.40%	0.70%
Valuation Allowance	2.60%	1.40%	1.80%
Other, net	0.00%	(0.40%)	(0.30%)
Domestic State and Local Income Taxes, net	1.70%	2.40%	2.40%
Foreign Tax Effects	0.90%	0.20%	0.50%
Worldwide Changes in Unrecognized Tax Benefits	0.00%	(0.10%)	1.40%
Effective Income Tax Rate Reconciliation, Percent, Total	25.80%	23.60%	24.40%