Summary of Significant Accounting Policies Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 146,528	$ 134,833
Total operating revenue	147,737	125,563
Total non-regulated revenue	5,572	3,827
Regulated Water and WasteWater Services
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	146,528	134,833
Regulatory balancing account revenue	1,209	(9,270)
Total operating revenue	147,737	125,563
Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	101,371	92,544
Business
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	27,721	27,693
Industrial
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,043	7,878
Public authorities
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,403	5,897
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,990	821
Operating and maintenance revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,087	2,499
Other non-regulated revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	860	765
Non-Regulated Services
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,947	3,264
Lease Income	625	563
Total non-regulated revenue	$ 5,572	$ 3,827

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Amount of lease income from operating, direct financing, and sales-type leases. Includes, but is not limited to, variable lease payments, interest income, profit (loss) recognized at commencement, and lease payments paid and payable to lessor.

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