Debt and Credit Arrangements Debt Transactions (Details) - 4.75% Notes Due 2030 (less unamortized discount and issuance costs of $3.7 and $6.0, respectively) $ in Millions	Jun. 30, 2020 USD ($)
Debt Instrument [Line Items]
Par Value	$ 650.0
Debt Instrument, Interest Rate, Stated Percentage	4.75%
Unsecured Debt	$ 640.0
Debt Instrument, Unamortized Discount	3.8
Debt Issuance Costs, Gross	$ 6.2

Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after accumulated amortization, of debt discount.

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Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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