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- Definition

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- Definition

Balancing and Memorandum Account, Refunds (Collections)

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- Definition

Balancing and Memorandum Cost Recovery Account, Increase (Decrease)

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- Definition

Balancing and Memorandum Cost Recovery Account, Refunds (Collections)

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- Definition

Balancing and Memorandum Revenue Account, Increase (Decrease)

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- Definition

Regulatory Balancing and Memorandum Accounts,, Net Under-Collected

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- Definition

Threshold balance of regulatory balancing or memorandum accounts as a percentage of authorized revenue to trigger an account review.

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- Definition

Regulatory Rate Case Filings, Requested Authorization For Equity Issuance, Amount

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- Definition

Regulatory Rate Filings, Balancing And Memorandum Account, Requested Recovery (Refund)

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- Definition

Regulatory Rate Filings, Proposed Rate Increase, Percent of Authorized Revenue, Year Two

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- Definition

Regulatory Rate Filings, Requested Authorization For Capital Budget, Amount

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- Definition

Regulatory Rate Filings, Requested Authorization For Debt Issuance, Amount

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- Definition

Regulatory Rate Filings, Requested Deferment Period

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- Definition

Regulatory Rate Filings, Requested Increase In Revenues

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- Definition

Regulatory Rate Filings, Requested Increase In Revenues, Completed Infrastructure Investments Not Currently In Approved Rates And Surcharges

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- Definition

Regulatory Rate Filings, Requested Rate Increase as Percentage of Total Revenue at Time of Request, Year Three

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- Definition

Regulatory Rate Filings, Requested Rate Increase, Year One

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- Definition

Regulatory Rate Filings, Requested Rate Increase, Year Three

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- Definition

Regulatory Rate Filings, Requested Rate Increase, Year Two

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- Definition

Regulatory Rate Filings, Requested Rate Increase as Percentage of Total Revenue at Time of Request, Year One

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- Definition

Requested WICA Surcharge Increase (Decrease), Percentage

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- Definition

Requested WICA Surcharge Increase, Increase In Revenues

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- Definition

Requested WICA Surcharge, Percentage

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- Definition

Requested WISC Surcharge Increase (Decrease), Percentage

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Amount of public utility's requested rate increase (decrease) with regulatory agency.

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Summary of Significant Accounting Policies - Regulatory Rate Filings (Details)								12 Months Ended
	Jan. 15, 2021 USD ($)	Jan. 05, 2021	Nov. 23, 2020 USD ($)	Oct. 28, 2020 USD ($)	Jan. 22, 2020	Jan. 20, 2020 USD ($)	Jan. 01, 2019 USD ($) ft³	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jan. 04, 2021 USD ($)	Apr. 10, 2020 USD ($)	Feb. 07, 2020	Jan. 28, 2020
Public Utilities, General Disclosures [Line Items]
Regulatory Asset Increase (Decrease)								$ 8,324,000	$ 962,000
Regulatory Asset Increase (Decrease)								2,516,000	(4,984,000)
Regulatory Balancing and Memorandum Accounts, Net Under-Collected								1,586,000
Refunds (Collections) Adjustments								(127,000)	(2,603,000)
Balancing and Memorandum Account, Refunds (Collections)								$ (9,340,000)	25,108,000
Regulatory Balancing and Memorandum Accounts Review, Authorized Revenue, Threshold Percentage								2.00%
PRVMA
Public Utilities, General Disclosures [Line Items]
Regulatory Asset Increase (Decrease)								$ 1,219,000
Refunds (Collections) Adjustments								(111,000)
CEMA
Public Utilities, General Disclosures [Line Items]
Regulatory Asset Increase (Decrease)								2,266,000
Refunds (Collections) Adjustments								0
2018 WCMA
Public Utilities, General Disclosures [Line Items]
Regulatory Asset Increase (Decrease)									(9,386,000)
2017 WCMA
Public Utilities, General Disclosures [Line Items]
Regulatory Asset Increase (Decrease)									1,182,000
2017 WCMA Reserve Recorded
Public Utilities, General Disclosures [Line Items]
Regulatory Asset Increase (Decrease)									1,169,000
Cost of capital memorandum accounts
Public Utilities, General Disclosures [Line Items]
Regulatory Asset Increase (Decrease)								(8,000)	(30,000)	$ (1,379,000)
Tax memorandum account
Public Utilities, General Disclosures [Line Items]
Regulatory Asset Increase (Decrease)								(2,000)	(139,000)	$ (6,504,000)
San Jose Water Company \| Application No. 20-04-009
Public Utilities, General Disclosures [Line Items]
Regulatory Rate Filings, Requested Authorization For Debt Issuance, Amount												$ 300,000,000
Regulatory Rate Case Filings, Requested Authorization For Equity Issuance, Amount												$ 50,000,000
San Jose Water Company \| Cost Of Capital Filings
Public Utilities, General Disclosures [Line Items]
Regulatory Rate Filings, Requested Deferment Period					1 year
San Jose Water Company \| General Rate Case No. 21-01-003 \| Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase, Year One											$ 51,585,000
Requested Rate Increase, Year One, Percentage											13.35%
Requested Rate Increase, Year Two											$ 16,932,000
Requested Rate Increase, Year Two, Percentage											3.88%
Requested Rate Increase, Year Three											$ 19,195,000
Requested Rate Increase, Year Three, Percentage											4.24%
Balancing And Memorandum Account, Requested Recovery (Refund)											$ 18,499,000
Regulatory Rate Filings, Requested Authorization For Capital Budget, Amount											$ 435,000,000
San Jose Water Company \| Advice Letter No. 532 \| 2018 WCMA
Public Utilities, General Disclosures [Line Items]
Regulatory Asset Increase (Decrease)									(9,386,000)
San Jose Water Company \| Advice Letter No. 532 \| 2019 WCMA
Public Utilities, General Disclosures [Line Items]
Regulatory Asset Increase (Decrease)									(639,000)
San Jose Water Company \| Advice Letter No. 528/528A
Public Utilities, General Disclosures [Line Items]
Refunds (Collections) Adjustments							$ 27,045,000
Balancing And Memorandum Account, Approved Recovery Period							12 months
Balancing and Memorandum Account, Refunds (Collections)								$ 151,000	$ 25,108,000
Balancing And Memorandum Account, Approved Recovery, Surcharge Per Cubic Foot \| ft³							0.005894
San Jose Water Company And Three Other California Water Utilities \| Cost Of Capital Filings \| Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Rate Filings, Requested Deferment Period		1 year
Connecticut Water Company
Public Utilities, General Disclosures [Line Items]
Authorized WICA Surcharge, Percentage								5.75%
Requested WICA Surcharge Increase (Decrease), Percentage				1.11%									(0.09%)	2.60%
Requested WICA Surcharge, Percentage				6.94%									5.75%	5.84%
Regulatory Rate Filings, Requested Rate Increase, Increase In Revenues				$ 956,000
Connecticut Water Company \| Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Rate Filings, Requested Increase In Revenues	$ 20,206,000
Regulatory Rate Filings, Requested Increase In Revenues, Completed Infrastructure Investments Not Currently In Approved Rates And Surcharges	$ 265,514,000
Avon Water Company
Public Utilities, General Disclosures [Line Items]
Authorized WICA Surcharge, Percentage								9.31%
Requested WICA Surcharge Increase (Decrease), Percentage													(0.05%)
Requested WICA Surcharge, Percentage													9.26%
Maine Water Company
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 304,000			$ 371,000
Maine Water Company \| Minimum
Public Utilities, General Disclosures [Line Items]
Requested WISC Surcharge Increase (Decrease), Percentage			1.10%			1.76%
Maine Water Company \| Maximum
Public Utilities, General Disclosures [Line Items]
Requested WISC Surcharge Increase (Decrease), Percentage			5.00%			3.00%