Derivatives - Interest Rate Swaps (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2024		Sep. 30, 2023		Sep. 30, 2024		Sep. 30, 2023		Dec. 31, 2023
Derivatives
Tax benefit (expense)		$ 1.7		$ (0.5)		$ 0.6		$ (1.9)
Unrealized gain (loss) on designated cash flow hedge	[1]	(4.9)	[2]	1.7	[3]	(1.8)	[4]	6.2	[5]
Fair value of derivative assets—current		40.3				40.3				$ 76.9
Fair value of derivative assets—long-term		13.9				13.9				27.0
Fair value of derivative liabilities—current		(32.5)				(32.5)				(62.7)
Fair value of derivative liabilities—long-term		(13.7)				(13.7)				(26.7)
Interest income		1.5		1.4		4.5		3.0
Interest rate swap
Derivatives
Change in fair value of interest rate swap		(6.6)		2.2		(2.4)		8.1
Tax benefit (expense)		1.7		(0.5)		0.6		(1.9)
Unrealized gain (loss) on designated cash flow hedge		(4.9)		$ 1.7		(1.8)		$ 6.2
Fair value of derivative assets—current		0.0				0.0				3.3
Fair value of derivative liabilities—current		(0.2)				(0.2)				0.0
Fair value of derivative liabilities—long-term		(1.3)				(1.3)				(2.4)
Net fair value of commodity derivatives		(1.5)				(1.5)				0.9
Commodity swaps
Derivatives
Fair value of derivative assets—current		40.3				40.3				73.6
Fair value of derivative assets—long-term		13.9				13.9				27.0
Fair value of derivative liabilities—current		(32.3)				(32.3)				(62.7)
Fair value of derivative liabilities—long-term		(12.4)				(12.4)				(24.3)
Net fair value of commodity derivatives		$ 9.5				$ 9.5				$ 13.6

[1] Includes tax benefit of $1.7 million and $0.6 million for the three and nine months ended September 30, 2024, respectively, and tax expense of $0.5 million and $1.9 million for the three and nine months ended September 30, 2023, respectively.

[2] Includes tax benefit of $1.7 million for the three months ended September 30, 2024.

[3] Includes tax expense of $0.5 million for the three months ended September 30, 2023.

[4] (1)Includes tax benefit of $0.6 million for the nine months ended September 30, 2024.

[5] Includes tax expense of $1.9 million for the nine months ended September 30, 2023.