PROPERTY, PLANT AND EQUIPMENT - Narrative (Details) - CAD ($) $ in Millions	12 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Disclosure of detailed information about property, plant and equipment [line items]
Depreciation	$ 182.8	$ 163.1
Cost of sales
Disclosure of detailed information about property, plant and equipment [line items]
Depreciation	180.9	160.7
Selling, general and administrative expenses
Disclosure of detailed information about property, plant and equipment [line items]
Depreciation	$ 0.5	$ 0.2

The amount of depreciation of property, plant and equipment. [Refer: Depreciation and amortisation expense; Property, plant and equipment]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 16
-IssueDate 2023-01-01
-Paragraph 73
-Subparagraph e
-Clause vii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=16&code=ifrs-tx-2023-en-r&anchor=para_73_e_vii&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 16
-IssueDate 2023-01-01
-Paragraph 75
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=16&code=ifrs-tx-2023-en-r&anchor=para_75_a&doctype=Standard
-URIDate 2023-03-23

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