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, 2020 CAD ($) km	Dec. 31, 2019 CAD ($)
Jointly Owned Pipleline lateral
Jointly Owned Utility Plant, Proportionate Ownership Share	50.00%
Jointly Owned Utility Plant, Name	Pipeline lateral
Length of pipeline, in miles \| km	26
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service	$ 34
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation	0
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	$ 0	$ 8

The length of pipeline lateral.

No definition available.

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 10.C)
-URI http://asc.fasb.org/extlink&oid=115995737&loc=d3e659983-123033

+ Details

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Balance Type:	debit
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- Definition

Identifies the name or location used by the utility of a jointly owned utility plant.

+ References

+ Details

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- References

No definition available.

+ Details

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- Definition

The period end amount of construction work in progress at a jointly owned electricity generation plant.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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- Definition

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

+ References

+ Details

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- Definition

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

+ References

+ Details

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- Details

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- Details

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- Details

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