Contingencies - 2023 Business Interruption Insurance Settlement (Details) $ in Millions	Sep. 30, 2023 CAD ($)
Lytton B.C wildfire & B.C Fraser canyon flooding
Gain Contingencies [Line Items]
Former Gain Contingency, Recognized in Current Period	$ 51

Amount of gain recognized in the period that had been disclosed in prior periods as a contingent gain.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 30
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=6397426&loc=d3e17499-108355

Name:	us-gaap_FormerGainContingencyRecognizedInCurrentPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant