Risk Management and Derivatives: Derivatives by Balance Sheet Classification (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ (0.3)	$ (2.8)
Commodity Contract \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(1.2)	(3.0)
Location, Statement of Financial Position, Balance [Axis]: us-gaap:DerivativeLiabilitiesCurrent \| Commodity Contract \| Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	(0.3)	(2.8)
Location, Statement of Financial Position, Balance [Axis]: us-gaap:DerivativeLiabilitiesCurrent \| Commodity Contract \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	(1.1)	(3.0)
Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesNoncurrent \| Commodity Contract \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ (0.1)	$ 0.0