INVENTORY (Details) - CAD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Natural gas	$ 776,000,000	$ 695,000,000
Crude oil	482,000,000	744,000,000
Other commodities	81,000,000	89,000,000
Total	1,339,000,000	1,528,000,000
Inventory adjustments	$ 93,000,000	$ 0	$ 0

Carrying amount as of the balance sheet date of natural gas in storage, which is a mixture of gases (liquefied or otherwise), used for fuel and manufacturing purposes, which is ready for sale.

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Amount of inventory reserves for last-in first-out (LIFO) and other inventory valuation methods.

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Carrying amount as of the balance sheet date of finished goods inventories for petroleum products, crude oil, petrochemical products, and other oil and gas inventories.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Amount, after of valuation reserves and allowances, of inventory, classified as other, expected to be sold, or consumed within one year or operating cycle, if longer.

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