Note 6 - Income Taxes (Details Textual) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
Income Taxes Receivable	$ 116.7	$ 90.5
Unrecognized Tax Benefits	78.0	80.9	$ 89.1	$ 78.5
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	63.4	65.6
Income Tax Examination, Penalties and Interest Accrued, Total	7.8	5.3	$ 4.3
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$ 13.1	$ 9.0
Domestic Tax Jurisdiction [Member]
Open Tax Year	2017 2018 2019 2020 2021 2022 2023 2024
State and Local Jurisdiction [Member]
Open Tax Year	2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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The amount of estimated penalties and interest accrued as of the balance sheet date arising from income tax examinations.

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Carrying amount as of the balance sheet date of income taxes previously overpaid to tax authorities (such as U.S. Federal, state and local tax authorities) representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes. Also called income tax refund receivable.

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Tax year that remains open to examination under enacted tax laws, in YYYY format.

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Amount of unrecognized tax benefits.

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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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