Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 1,108,094	$ 1,017,104
Regulated Operating Revenue, Other	8,588	6,009
Revenues	1,160,086	1,046,130
Electricity, US Regulated [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	664,102	607,693
Natural Gas, US Regulated [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	387,863	365,637
Other Revenue From Contracts with Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	56,129	43,774
Decoupling over-collection [Domain]
Disaggregation of Revenue [Line Items]
Regulated Operating Revenue, Other	(1,928)	1,150
Other Non-606 Revenue [Member]
Disaggregation of Revenue [Line Items]
Regulated Operating Revenue, Other	53,920	27,876
Subsidiaries [Member]
Disaggregation of Revenue [Line Items]
Regulated Operating Revenue, Other	8,588	6,009
Revenues	$ 1,160,086	$ 1,046,130
Puget LNG [Member]
Disaggregation of Revenue [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, 2026			$ 19,454
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction			19,454
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction			19,454
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction			102,135
Revenue, Remaining Performance Obligation, Amount			195,566
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, 2025			19,710
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, 2025			$ 15,359
Remaining Contract Term, PLNG			10 years