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Property, plant and equipment (Regulated and Non-regulated Assets) (Narrative) (Details) - Pipleline lateral - SeaCoast Gas Transmission, LLC - General plant and other $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) mi	Dec. 31, 2021 USD ($)
Jointly Owned Pipleline lateral
Jointly Owned Utility Plant, Proportionate Ownership Share	50.00%	50.00%
Length of pipeline, in miles | mi	26
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 27	$ 27
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	$ 1	$ 1

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- Definition

The length of pipeline lateral.

+ References

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- Definition

The period end amount owned by the reporting utility of a jointly owned utility plant in service.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 360
-Section S99
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- Definition

The period end amount of accumulated depreciation in a jointly owned electricity generation plant.

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- Definition

The proportionate share of interest (percent) in a jointly owned utility plant.

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-SubTopic 360
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