Summary of Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 198,660	$ 212,457	$ 357,592	$ 358,985
Regulatory balancing account revenue	7,534	666	21,595	1,875
Operating revenue	206,194	213,123	379,187	360,860
Total non-regulated revenue	7,002	5,374	12,199	10,946
Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	132,831	134,971	239,390	236,342
Business
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	39,278	35,730	71,441	63,452
Industrial
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,314	6,019	12,087	12,062
Public authorities
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	10,884	10,358	17,869	16,760
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9,353	25,379	16,805	30,369
Operating and maintenance revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,233	3,925	6,638	8,013
Other non-regulated revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,081	796	4,231	1,655
Non-regulated revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,314	4,721	10,869	9,668
Lease revenue	688	653	1,330	1,278
Total non-regulated revenue	$ 7,002	$ 5,374	12,199	$ 10,946
Insurance Programs
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers			$ 2,700