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Commitments and Contingent Liabilities - Narrative (Details) gal in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) gal	Sep. 30, 2024 USD ($)
Other Commitments [Line Items]
Estimated incremental borrowing rate	4.03%		4.03%
Expenditures for operating leases | $	$ 0.2	$ 0.2	$ 0.6	$ 0.6
NJWSA Untreated Water Agreement
Other Commitments [Line Items]
Average purchase of gallons a day under agreement (in mgd)			27.0
NJWSA Untreated Water Agreement | Maximum
Other Commitments [Line Items]
Average purchase of gallons a day under agreement (in mgd)			47.0
NJBPU Treated Water Agreement | Minimum
Other Commitments [Line Items]
Average purchase of gallons a day under agreement (in mgd)			3.0
City Of Dover Treated Water Contract | Maximum | Tidewater
Other Commitments [Line Items]
Average purchase of gallons annually under agreement (in gallons)			75.0
Construction Agreement
Other Commitments [Line Items]
Estimated future expenditure obligation | $	$ 18.9		$ 18.9

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- Definition

Estimated incremental borrowing rate.

+ References

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- Definition

The average purchase of gallons.

+ References

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- Definition

Purchase Obligation, Volume Per Year

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- Definition

Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 53
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479589/842-20-55-53

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-4

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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.

+ References

No definition available.

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- Definition

Minimum amount of purchase arrangement in which the entity has agreed to expend funds to procure goods or services from a supplier.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477314/942-235-S99-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-4

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-3

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