RELATED PARTY TRANSACTIONS - Subsidiary Transactions (Details) - Subsidiaries - CAD CAD in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Disclosure of transactions between related parties [line items]
Revenue	CAD 74	CAD 50
Purchases	198	189
Accounts receivable	80	70
Accounts payable and accrued liabilities	CAD 26	CAD 32

The amounts payable resulting from related party transactions. [Refer: Related parties [member]]

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- Definition

The amounts receivable resulting from related party transactions. [Refer: Related parties [member]]

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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.

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- Definition

The amount of goods purchased by the entity in related party transactions. [Refer: Related parties [member]]

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- Definition

The amount of revenue arising from the sale of goods in related party transactions. [Refer: Revenue; Related parties [member]]

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