COMMITMENTS (Details) - CAD ($) $ in Millions	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Disclosure of finance lease and operating lease by lessee [line items]
Expected future minimum lease payments payable under non-cancellable operating lease	$ 274.1	$ 240.0
Rental expense	65.1	68.2
Contractual capital commitments	291.7	223.2
No later than 1 year
Disclosure of finance lease and operating lease by lessee [line items]
Expected future minimum lease payments payable under non-cancellable operating lease	50.7	44.4
Contractual capital commitments	240.2	132.0
Later than 1 year and no later than 5 years
Disclosure of finance lease and operating lease by lessee [line items]
Expected future minimum lease payments payable under non-cancellable operating lease	136.9	118.9
Contractual capital commitments	51.5	90.7
Later than 5 years
Disclosure of finance lease and operating lease by lessee [line items]
Expected future minimum lease payments payable under non-cancellable operating lease	86.5	76.7
Contractual capital commitments	$ 0.0	$ 0.5

The amount of capital commitments for which the entity has entered into a contract. [Refer: Capital commitments]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 112
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_112_c&doctype=Standard
-URIDate 2018-03-16

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- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

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- Definition

The amount of future minimum lease payments payable under non-cancellable operating leases. Minimum lease payments are payments over the lease term that the lessee is or can be required to make, excluding contingent rent, costs for services and taxes to be paid by, and reimbursed to, the lessor, together with: (a) for a lessee, any amounts guaranteed by the lessee or by a party related to the lessee; or (b) for a lessor, any residual value guaranteed to the lessor by: (i) the lessee; (ii) a party related to the lessee; or (iii) a third party unrelated to the lessor that is financially capable of discharging the obligations under the guarantee.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2019-01-01
-Name IAS
-Number 17
-IssueDate 2018-01-01
-Paragraph 35
-Subparagraph a
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- Definition

The amount of expense recognised on rental activities.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Number 1
-IssueDate 2018-01-01
-Paragraph 85
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_85&doctype=Standard
-URIDate 2018-03-16

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