Provision for Taxes (Narratives) (Details) - USD ($) $ in Millions	12 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
Components of Deferred Tax Assets and Liabilities [Abstract]
Statutory federal income tax rate	21.00%	21.00%	21.00%
Tax adjustment settlements and unusual provisions	$ 66.0	$ 64.8
NOL and credit carryforwards, federal amount	129.0
NOL and credit carryfowards, state amount	816.8	628.9
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Unrecognized tax benefits, income tax penalties and interest accrued	19.0
Income Tax Examination, Interest Accrued	13.3	9.6
Unrecognized tax benefits, income tax penalties and interest expense	21.8	$ 20.2
Income Tax Examination, Penalties Accrued	$ 1.6

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards.

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

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

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

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Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

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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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Amount of expense 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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