INCOME TAXES - Cash paid for income taxes (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Tax Paid, by Individual Jurisdiction [Line Items]
Federal	$ 284.1	$ 276.4	$ 211.0
State	81.2	72.8	60.5
Foreign	26.3	13.2	14.9
Total cash paid for income taxes, net	391.6	362.4	286.4
Illinois
Income Tax Paid, by Individual Jurisdiction [Line Items]
State	45.0	$ 40.9	$ 36.1
United Kingdom
Income Tax Paid, by Individual Jurisdiction [Line Items]
Foreign	$ 23.7

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Amount, after income tax refund received, of cash paid to federal (national) tax jurisdiction for tax on income.

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Amount, after refund, of cash paid to foreign, federal, state, and local jurisdictions as income tax.

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