Commitments and Contingent Liabilities (Narrative) (Details) gal in Millions, $ in Millions	3 Months Ended
Mar. 31, 2021 USD ($) gal	Mar. 31, 2020 USD ($)
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Budgeted construction cost for construction program, 2020 \| $	$ 121.0
Contractual construction agreements \| $	17.0
Rental expenses under operating leases \| $	$ 0.2	$ 0.2
Estimated incremental borrowing rate	4.03%
NJ Water Supply Authority [Member]
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Purchase commitment expiration date of contract	Nov. 30, 2023
Water purchase per commitment \| gal	27.0
Regulated Water Authority [Member]
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Purchase commitment expiration date of contract	Feb. 27, 2026
Water purchase per commitment \| gal	3.0
City of Dover [Member]
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Water purchase per commitment \| gal	15.0

Budgeted construction cost for construction program, next year.

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- Definition

Estimated incremental borrowing rate.

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- Definition

The expiration date of a long-term purchase commitment.

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- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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No definition available.

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- Definition

The minimum amount the entity agreed to spend under the long-term purchase commitment.

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No definition available.

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- Definition

Number of units of goods that must be purchased within the specified time period of the agreement to avoid penalties or unfavorable effects on pricing, among other adverse consequences.

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No definition available.

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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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No definition available.

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