Derivative Instruments and Hedging Activities - Pro Forma Impact Of Offsetting Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Derivative Asset [Abstract]
Derivative assets	$ 145.2	$ 204.4
Pro forma net presentation, asset, current	$ 69.4	$ 44.9
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]	Derivative Asset Before Effects Of Master Netting Arrangements Current	Derivative Asset Before Effects Of Master Netting Arrangements Current
Pro forma net presentation, asset, noncurrent	$ 18.6	$ 7.3
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Derivative Asset Before Effects Of Master Netting Arrangements Noncurrent	Derivative Asset Before Effects Of Master Netting Arrangements Noncurrent
Pro forma net presentation, asset, total	$ 88.0	$ 52.2
Counterparties with Offsetting Positions or Collateral [Member]
Derivative Asset [Abstract]
Derivative assets	143.4	186.7
Pro forma net presentation, asset, total	86.2	34.5
Counterparties without Offsetting Position [Member]
Derivative Asset [Abstract]
Derivative assets	1.8	17.7
Pro forma net presentation, asset, current	0.2	17.7
Pro forma net presentation, asset, noncurrent	1.6
Pro forma net presentation, asset, total	1.8	17.7
Current Assets from Risk Management Activities [Member]
Derivative Asset [Abstract]
Derivative assets	111.9	179.9
Current Assets from Risk Management Activities [Member] | Counterparties with Offsetting Positions or Collateral [Member]
Derivative Asset [Abstract]
Derivative assets	111.7	162.2
Pro forma net presentation, asset	69.2	27.2
Current Assets from Risk Management Activities [Member] | Counterparties without Offsetting Position [Member]
Derivative Asset [Abstract]
Derivative assets	0.2	17.7
Other Long-term Assets [Member]
Derivative Asset [Abstract]
Derivative assets	33.3	24.5
Other Long-term Assets [Member] | Counterparties with Offsetting Positions or Collateral [Member]
Derivative Asset [Abstract]
Derivative assets	31.7	24.5
Pro forma net presentation, asset	17.0	$ 7.3
Other Long-term Assets [Member] | Counterparties without Offsetting Position [Member]
Derivative Asset [Abstract]
Derivative assets	$ 1.6