Unusual Items - Narrative (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2022
Debt Instrument [Line Items]
Gain (loss) on extinguishment of debt	$ (22.7)	$ (0.9)	$ (22.7)	$ (10.5)
2 1/4% Notes \| Convertible Debt
Debt Instrument [Line Items]
Gain (loss) on extinguishment of debt	$ (22.6)		$ (0.1)	(10.5)
Extinguishment of debt				$ 154.1
Converted instrument, shares settled (in shares)				2.9
Debt instrument interest rate stated percentage	2.25%	2.25%	2.25%	2.25%	2.25%
Unusual Items
Debt Instrument [Line Items]
Legal matters (component of other expense, net)	$ (0.4)	$ 0.0	$ 15.7	$ 0.0
Proxy contest and related litigation costs (component of other expense, net)	16.3	0.0	28.3	0.0
Terminated merger costs (component of other expense, net)	0.0	7.2	2.5	20.8
Gain (loss) on extinguishment of debt	$ (22.7)	$ (0.9)	$ (22.7)	$ (10.5)

The number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period.

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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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Gross amount of debt extinguished.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings.

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Amount of litigation expense, including but not limited to legal, forensic, accounting, and investigative fees.

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The amount of loss pertaining to the specified contingency that was charged against earnings in the period, including the effects of revisions in previously reported estimates.

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