Fair Value Measurements: Schedule of Fair Values (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Derivative Liability, Current	Derivative Liability, Current
Contract Subject to Master Netting
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 0.7	$ 1.9
Derivative Liability, Fair Value, Gross Liability	0.1	3.3
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	(0.7)	(1.9)
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	(0.1)	(3.3)
Fair Value, Measurements, Recurring | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value Disclosure	0.0	0.0
Derivative, Liabilities, Fair Value Disclosure	1.8	6.8
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value Disclosure	0.0	0.0
Derivative, Liabilities, Fair Value Disclosure	0.0	0.0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value Disclosure	0.7	1.9
Derivative, Liabilities, Fair Value Disclosure	1.9	10.1
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value Disclosure	0.0	0.0
Derivative, Liabilities, Fair Value Disclosure	0.0	0.0
Fair Value, Measurements, Recurring | Gas Utilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	(0.7)	(1.9)
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	(0.1)	(3.3)
Fair Value, Measurements, Recurring | Gas Utilities | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value Disclosure	0.0	0.0
Derivative, Liabilities, Fair Value Disclosure	1.8	6.8
Fair Value, Measurements, Recurring | Gas Utilities | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value Disclosure	0.0	0.0
Derivative, Liabilities, Fair Value Disclosure	0.0	0.0
Fair Value, Measurements, Recurring | Gas Utilities | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value Disclosure	0.7	1.9
Derivative, Liabilities, Fair Value Disclosure	1.9	10.1
Fair Value, Measurements, Recurring | Gas Utilities | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value Disclosure	0.0	0.0
Derivative, Liabilities, Fair Value Disclosure	$ 0.0	$ 0.0