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Commitments and Contingencies (Collaborative Arrangements) (Details) - Jointly Owned Electricity Generation Plant - NSPI - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Utilities Operating Expense, Purchased Power	$ 19	$ 19
Utilities Operating Expense, Maintenance and Operations	$ 3	$ 2

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- Definition

Amount of operating expense for routine plant maintenance, repairs and operations of regulated operation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(b))
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Amount of operating expense for purchased power of regulated operation.

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-Topic 220
-SubTopic 10
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