Inventory (Details) $ in Millions	12 Months Ended
Dec. 31, 2021 CAD ($) emissionCredit	Dec. 31, 2020 CAD ($) emissionCredit
Analysis of income and expenses [Line Items]
Additions to emission credits \| emissionCredit	2,033,752	1,434,761
Purchased emission credits	$ 55	$ 38
Inventory, emission credits \| emissionCredit	1,922,973	1,211,230
Inventory write-down	$ 65	$ 37
Increased depreciation from the accelerated closure	48
Write-downs	28	$ 0
OM&A
Analysis of income and expenses [Line Items]
Write-downs	$ 28

The amount of expense recognised related to the write-down of inventories to net realisable value. [Refer: Inventories]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 2
-IssueDate 2021-01-01
-Paragraph 36
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=2&code=ifrs-tx-2021-en-r&anchor=para_36_e&doctype=Standard
-URIDate 2021-03-24

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2021-01-01
-Paragraph 98
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2021-en-r&anchor=para_98_a&doctype=Standard
-URIDate 2021-03-24

Name:	ifrs-full_InventoryWritedown2011
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration