Fair Value Measurements - Changes in Fair Value of Level 3 (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Summary of net changes in fair value of the company's level 3 financial assets and liabilities
Realized loss on derivative instruments	$ (54.3)	$ 16.5	$ (14.5)	$ (73.2)
Unrealized gain (loss) on derivative instruments	(36.3)	28.1	18.8	(47.5)
Level 3
Summary of net changes in fair value of the company's level 3 financial assets and liabilities
Beginning Balance at January 1,			(73.8)	(27.9)
Realized loss on derivative instruments			(33.3)	(25.7)
Unrealized gain (loss) on derivative instruments			18.8	(47.5)
Settlements			33.3	25.7
Ending Balance at September 30,	$ (55.0)	$ (75.4)	$ (55.0)	$ (75.4)

Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Fair value of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

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