Summary of Consolidation and Significant Accounting Policy - Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2022 USD ($) mi²	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Puget LNG [Member]
Summary of Consolidation Policy
Operating Costs and Expenses	$ 7.8	$ 0.9
Subsidiaries [Member]
Summary of Consolidation Policy
Area of Service Territory (in sqmi) | mi²	6,000
Subsidiaries [Member] | Skookumchuck Wind Energy Project
Summary of Consolidation Policy
Contract Length, PPA	20 years
Variable Interest Entity, Measure of Activity, Expense	$ 10.0	$ 12.3
Variable Interest Entity, Payable	$ 1.3		$ 2.7
Subsidiaries [Member] | Golden Hills Wind Farm
Summary of Consolidation Policy
Contract Length, PPA	20 years
Variable Interest Entity, Measure of Activity, Expense	$ 10.6
Variable Interest Entity, Payable	2.5
Subsidiaries [Member] | Natural Gas, US Regulated [Member] | Tacoma LNG [Member]
Summary of Consolidation Policy
Construction in Progress, Gross			239.6
Public Utilities, Property, Plant and Equipment, Generation or Processing	$ 242.2
Subsidiaries [Member] | Tacoma LNG [Member]
Summary of Consolidation Policy
Jointly Owned Non-Utility Plant Share	43.00%
Puget LNG [Member]
Summary of Consolidation Policy
Jointly Owned Non-Utility Plant Share	57.00%
Puget LNG [Member] | Natural Gas, US Regulated [Member] | Tacoma LNG [Member]
Summary of Consolidation Policy
Jointly Owned Non-Utility Plant, Ownership Amount of Other Assets	$ 245.3
Construction in Progress, Gross			$ 244.7
Variable Interest Entity, Not Primary Beneficiary | Skookumchuck Wind Energy Project
Summary of Consolidation Policy
Equity Method Investments	0.0
Variable Interest Entity, Not Primary Beneficiary | Golden Hills Wind Farm
Summary of Consolidation Policy
Equity Method Investments	$ 0.0