Summary of Significant Accounting Policies Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 134,833	$ 117,410
Total operating revenue	125,563	126,111
Total non-regulated revenue	3,827	4,901
Regulated Water and WasteWater Services
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	134,833	117,410
Regulatory balancing account revenue	(9,270)	8,701
Total operating revenue	125,563	126,111
Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	92,544	84,259
Business
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	27,693	25,481
Industrial
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	7,878	7,264
Public authorities
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5,897	4,471
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	821	(4,065)
Operating and maintenance revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,499	3,046
Other non-regulated revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	765	1,296
Non-Regulated Services
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,264	4,342
Lease Income	563	559
Total non-regulated revenue	$ 3,827	$ 4,901

Regulatory Balancing Account Revenue

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919372-209981

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The amount of regulated water operating revenues recognized during the period.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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The amount of unregulated operating revenues recognized during the period.

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