DECOMMISSIONING AND RESTORATION LIABILITY (Details) - Provision for decommissioning, restoration and rehabilitation costs [member] - CAD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Decommissioning And Restoration Liability [Line Items]
Expected undiscounted cash flows	$ 30,045	$ 24,937
Discount rate	2.26%	2.31%
Inflation rate	1.99%	2.08%
Periods	2028	2028

The expected rate of inflation that is used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit plans [member]; Defined benefit obligation, at present value; Actuarial assumptions [member]]

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The discount rate applied to cash flow projections for a cash-generating unit (group of units). [Refer: Cash-generating units [member]]

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The description of periods when cash flows are expected to occur for cash flow hedges. [Refer: Cash flow hedges [member]]

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The amount of contractual undiscounted cash flows in relation to non-derivative financial liabilities.

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