Canadian Natural Resources Limited (CNQ) 40-F 22 Mar 18 2017 FY Annual report (Canada) Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION	12 Months Ended
	Dec. 31, 2017shares
Document And Entity Information [Abstract]
Entity Registrant Name	CANADIAN NATURAL RESOURCES LTD
Entity Central Index Key	1,017,413
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Document Type	40-F
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding	1,222,769,000

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 137	$ 17
Accounts receivable	2,397	1,434
Current income taxes receivable	322	851
Inventory	894	689
Prepaids and other	175	149
Investments	893	913
Current portion of other long-term assets	79	283
Current assets	4,897	4,336
Non-current assets
Exploration and evaluation assets	2,632	2,382
Property, plant and equipment	65,170	50,910
Other long-term assets	1,168	1,020
Assets	73,867	58,648
Current liabilities
Accounts payable	775	595
Accrued liabilities	2,597	2,222
Current portion of long-term debt	1,877	1,812
Current portion of other long-term liabilities	1,012	463
Current liabilities	6,261	5,092
Non-current liabilities
Long-term debt	20,581	14,993
Other long-term liabilities	4,397	3,223
Deferred income tax liabilities	10,975	9,073
Liabilities	42,214	32,381
SHAREHOLDERS’ EQUITY
Share capital	9,109	4,671
Retained earnings	22,612	21,526
Accumulated other comprehensive income (loss)	(68)	70
Shareholders' equity	31,653	26,267
Liabilities and shareholders' equity	$ 73,867	$ 58,648

CONSOLIDATED STATEMENTS OF EARN

CONSOLIDATED STATEMENTS OF EARNINGS (LOSS) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue [abstract]
Product sales	$ 17,669	$ 11,098	$ 13,167
Less: royalties	(1,018)	(575)	(804)
Revenue	16,651	10,523	12,363
Expenses
Production	5,596	4,099	4,726
Transportation, blending and feedstock	2,917	2,003	2,379
Depletion, depreciation and amortization	5,186	4,858	5,483
Administration	319	345	390
Share-based compensation	134	355	(46)
Asset retirement obligation accretion	164	142	173
Interest and other financing expense	631	383	322
Risk management activities	35	33	(469)
Foreign exchange (gain) loss	(787)	(55)	761
Gain on acquisition, disposition and revaluation of properties	(379)	(250)	(739)
(Gain) loss from investments	(38)	(327)	50
Total Expenses	13,778	11,586	13,030
Earnings (loss) before taxes	2,873	(1,063)	(667)
Current income tax recovery	(164)	(618)	(261)
Deferred income tax expense (recovery)	640	(241)	231
Net earnings (loss)	$ 2,397	$ (204)	$ (637)
Net earnings (loss) per common share
Basic earnings (loss) per share	$ 2.04	$ (0.19)	$ (0.58)
Diluted earnings (loss) per share	$ 2.03	$ (0.19)	$ (0.58)

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of comprehensive income [abstract]
Net earnings (loss)	$ 2,397	$ (204)	$ (637)
Net change in derivative financial instruments designated as cash flow hedges
Unrealized income (loss), net of taxes of $9 million (2016 – $3 million, 2015 – $2 million)	53	(18)	(23)
Reclassification to net earnings (loss), net of taxes of $5 million (2016 – $2 million, 2015 – $2 million)	(33)	(13)	(13)
Net change in derivative financial instruments designated as cash flow hedges	20	(31)	(36)
Foreign currency translation adjustment
Translation of net investment	(158)	26	60
Other comprehensive income (loss), net of taxes	(138)	(5)	24
Comprehensive income (loss)	$ 2,259	$ (209)	$ (613)

CONSOLIDATED STATEMENTS OF COM5

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of comprehensive income [abstract]
Unrealized income (loss), tax	$ 9	$ 3	$ 2
Reclassification to net earnings (loss), tax	$ 5	$ 2	$ 2

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - CAD ($) $ in Millions		Total	AOSP	Share capital	Retained earnings	Accumulated other comprehensive income (loss)
Balance – beginning of year at Dec. 31, 2014				$ 4,432	$ 24,408	$ 51
Issued for the acquisition of AOSP and other assets	[1]			0
Issued upon exercise of stock options				91
Previously recognized liability on stock options exercised for common shares				18
Return of capital on PrairieSky Royalty Ltd. share distribution				0
Net earnings (loss)		$ (637)			(637)
Dividends on common shares					(1,006)
Other comprehensive income (loss), net of taxes		24				24
Balance – end of year at Dec. 31, 2015		27,381		4,541	22,765	75
Issued for the acquisition of AOSP and other assets	[1]			0
Issued upon exercise of stock options				559
Previously recognized liability on stock options exercised for common shares				117
Return of capital on PrairieSky Royalty Ltd. share distribution				(546)
Net earnings (loss)		(204)			(204)
Dividends on common shares					(1,035)
Other comprehensive income (loss), net of taxes		(5)				(5)
Balance – end of year at Dec. 31, 2016		26,267		4,671	21,526	70
Issued for the acquisition of AOSP and other assets	[1]			3,818
Issued upon exercise of stock options				466
Previously recognized liability on stock options exercised for common shares				154
Return of capital on PrairieSky Royalty Ltd. share distribution				0
Net earnings (loss)		2,397			2,397
Dividends on common shares					(1,311)
Other comprehensive income (loss), net of taxes		(138)				(138)
Balance – end of year at Dec. 31, 2017		$ 31,653		$ 9,109	$ 22,612	$ (68)
Non-cash share considerations issued on the acquisition of AOSP and other assets			$ 3,818
[1]	During 2017, in connection with the acquisition of direct and indirect interests in the Athabasca Oil Sands Project ("AOSP") and other assets, the Company issued non-cash share consideration of $3,818 million. See note 7.

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - CAD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net earnings (loss)		$ 2,397	$ (204)	$ (637)
Non-cash items
Depletion, depreciation and amortization		5,186	4,858	5,483
Share-based compensation		134	355	(46)
Asset retirement obligation accretion		164	142	173
Unrealized risk management loss		37	25	374
Unrealized foreign exchange (gain) loss		(821)	(93)	858
(Gain) loss from investments		(11)	(299)	55
Deferred income tax expense (recovery)		640	(241)	231
Gain on acquisition, disposition and revaluation of properties		(379)	(250)	(739)
Current income tax on disposition of properties		0	0	33
Other		(110)	(32)	(22)
Abandonment expenditures		(274)	(267)	(370)
Net change in non-cash working capital		299	(542)	239
Cash flows from operating activities		7,262	3,452	5,632
Financing activities
Issue of bank credit facilities and commercial paper, net		2,222	342	970
Issue of medium-term notes, net		1,791	998	107
Issue (repayment) of US dollar debt securities, net		2,733	(834)	0
Issue of common shares on exercise of stock options		466	559	91
Dividends on common shares		(1,252)	(758)	(1,251)
Net change in non-cash working capital		0	0	(40)
Cash flows from (used in) financing activities		5,960	307	(123)
Investing activities
Net (expenditures) proceeds on exploration and evaluation assets	[1]	(124)	6	236
Net expenditures on property, plant and equipment	[1],[2]	(4,574)	(3,803)	(4,704)
Acquisition of AOSP and other assets, net of cash acquired	[3]	(8,630)	0	0
Current income tax on disposition of properties		0	0	(33)
Investment in other long-term assets		(87)	(99)	(112)
Net change in non-cash working capital, investing activities		313	85	(852)
Cash flows used in investing activities		(13,102)	(3,811)	(5,465)
Increase (decrease) in cash and cash equivalents		120	(52)	44
Cash and cash equivalents – beginning of year		17	69	25
Cash and cash equivalents – end of year		137	17	69
Interest paid, net		725	617	541
Income taxes (received) paid		(792)	(444)	42
Investment in PrairieSky Royalty Ltd.
Investing activities
Non-cash share consideration received				$ 985
Disposal of Cold Lake Pipeline | Investment in Inter Pipeline Ltd.
Investing activities
Non-cash share consideration received			$ 190
AOSP
Investing activities
Other working capital		291
Fair value of share considerations issued		$ 3,818
[1]	Net proceeds on exploration and evaluation assets and net expenditures on property, plant and equipment in 2015 exclude non-cash share consideration of $985 million received from PrairieSky Royalty Ltd. ("PrairieSky") on the disposition of royalty income assets.
[2]	Net expenditures on property, plant and equipment in 2016 exclude non-cash share consideration of $190 million received from Inter Pipeline Ltd. ("Inter Pipeline") on the disposition of the Company's interest in the Cold Lake Pipeline.
[3]	The acquisition of AOSP in 2017 includes net working capital of $291 million and excludes non-cash share consideration of $3,818 million. See note 7.

ACCOUNTING POLICIES

ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2017
Corporate Information And Statement Of IFRS Compliance [Abstract]
ACCOUNTING POLICIES	ACCOUNTING POLICIES Canadian Natural Resources Limited (the “Company”) is a senior independent crude oil and natural gas exploration, development and production company. The Company’s exploration and production operations are focused in North America, largely in Western Canada; the United Kingdom (“UK”) portion of the North Sea; and Côte d’Ivoire, Gabon, and South Africa in Offshore Africa. The "Oil Sands Mining and Upgrading" segment produces synthetic crude oil through bitumen mining and upgrading operations at Horizon Oil Sands ("Horizon") and through the Company's direct and indirect interest in the Athabasca Oil Sands Project ("AOSP"). Within Western Canada, the Company maintains certain midstream activities that include pipeline operations, an electricity co-generation system and an investment in the North West Redwater Partnership ("Redwater Partnership"), a general partnership formed in the Province of Alberta. The Company was incorporated in Alberta, Canada. The address of its registered office is 2100, 855 - 2 Street S.W., Calgary, Alberta, Canada. The Company’s consolidated financial statements and the related notes have been prepared in accordance with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”). The accounting policies adopted by the Company under IFRS are set out below. The Company has consistently applied the same accounting policies throughout all periods presented, except where IFRS permits new accounting standards to be adopted prospectively. (A) PRINCIPLES OF CONSOLIDATION The consolidated financial statements have been prepared under the historical cost basis, unless otherwise required. The consolidated financial statements include the accounts of the Company and all of its subsidiary companies and wholly owned partnerships. Subsidiaries are all entities over which the Company has control. Subsidiaries are consolidated from the date on which the Company obtains control. They are deconsolidated from the date that control ceases. Certain of the Company’s activities are conducted through joint arrangements in which two or more parties have joint control. Where the Company has determined that it has a direct ownership interest in jointly controlled assets and obligations for the liabilities (a “joint operation”), the assets, liabilities, revenue and expenses related to the joint operation are included in the consolidated financial statements in proportion to the Company’s interest. Where the Company has determined that it has an interest in jointly controlled entities (a “joint venture”), it uses the equity method of accounting. Under the equity method, the Company’s initial and subsequent investments are recognized at cost and subsequently adjusted for the Company’s share of the joint venture’s income or loss, less distributions received. Joint ventures accounted for using the equity method of accounting are tested for impairment whenever objective evidence indicates that the carrying amount of the investment may not be recoverable. Indications of impairment include a history of losses, significant capital expenditure overruns, liquidity concerns, financial restructuring of the investee or significant adverse changes in the technological, economic or legal environment. The amount of the impairment is measured as the difference between the carrying amount of the investment and the higher of its fair value less costs of disposal and its value in use. Impairment losses are reversed in subsequent periods if the amount of the loss decreases and the decrease can be related objectively to an event occurring after the impairment was recognized. (B) SEGMENTED INFORMATION Operating segments have been determined based on the nature of the Company’s activities and the geographic locations in which the Company operates, and are consistent with the level of information regularly provided to and reviewed by the Company’s chief operating decision makers. (C) CASH AND CASH EQUIVALENTS Cash comprises cash on hand and demand deposits. Other investments (term deposits and certificates of deposit) with an original term to maturity at purchase of three months or less are reported as cash equivalents in the consolidated balance sheets. (D) INVENTORY Inventory is primarily comprised of product inventory and materials and supplies. Product inventory is comprised of crude oil held for sale, including pipeline linefill and crude oil stored in floating production, storage and offloading vessels. Inventories are carried at the lower of cost and net realizable value. Cost consists of purchase costs, direct production costs, directly attributable overhead and depletion, depreciation and amortization and is determined on a first-in, first-out basis. Net realizable value for product inventory is determined by reference to forward prices, and for materials and supplies is based on current market prices as at the date of the consolidated balance sheets. (E) EXPLORATION AND EVALUATION ASSETS Exploration and evaluation (“E&E”) assets consist of the Company’s crude oil and natural gas exploration projects that are pending the determination of proved reserves. E&E costs are initially capitalized and include costs directly associated with the acquisition of licenses, technical services and studies, seismic acquisition, exploration drilling and evaluation, overhead and administration expenses, and the estimate of any asset retirement costs. E&E costs do not include general prospecting or evaluation costs incurred prior to having obtained the legal rights to explore an area. These costs are recognized in net earnings. Once the technical feasibility and commercial viability of E&E assets are determined and a development decision is made by management, the E&E assets are tested for impairment upon reclassification to property, plant and equipment. The technical feasibility and commercial viability of extracting a mineral resource is considered to be determined when an assessment of proved reserves is made. An E&E asset is derecognized upon disposal or when no future economic benefits are expected to arise from its use. Any gain or loss arising on derecognition of the asset is recognized in net earnings within depletion, depreciation and amortization. E&E assets are also tested for impairment when facts and circumstances suggest that the carrying amount of E&E assets may exceed their recoverable amount, by comparing the relevant costs to the fair value of the related Cash Generating Units (“CGUs”), aggregated at a segment level. Indications of impairment include leases approaching expiry, the existence of low benchmark commodity prices for an extended period of time, significant downward revisions in estimated probable reserves volumes, significant increases in estimated future exploration or development expenditures, or significant adverse changes in the applicable legislative or regulatory frameworks. (F) PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment is measured at cost less accumulated depletion and depreciation and impairment provisions. Assets under construction are not depleted or depreciated until available for their intended use. The capitalized value of a finance lease is included in property, plant and equipment. Exploration and Production The cost of an asset comprises its acquisition costs, construction and development costs, costs directly attributable to bringing the asset into operation, the estimate of any asset retirement costs, and applicable borrowing costs. Property acquisition costs are comprised of the aggregate amount paid and the fair value of any other consideration given to acquire the asset. When significant components of an item of property, plant and equipment, including crude oil and natural gas interests, have different useful lives, they are accounted for separately. Crude oil and natural gas properties are depleted using the unit-of-production method over proved reserves, except for major components, which are depreciated using a straight-line method over their estimated useful lives. The unit-of-production depletion rate takes into account expenditures incurred to date, together with future development expenditures required to develop proved reserves. Oil Sands Mining and Upgrading Capitalized costs for the Oil Sands Mining and Upgrading segment are reported separately from the Company’s North America Exploration and Production segment. Capitalized costs include acquisition costs, construction and development costs, costs directly attributable to bringing the asset into operation, the estimate of any asset retirement costs, and applicable borrowing costs. Mine-related costs are depleted using the unit-of-production method based on proved reserves. Costs of the upgraders and related infrastructure located on the Horizon and AOSP sites are depreciated on the unit-of-production method based on the estimated productive capacity of the respective upgraders and related infrastructure. Other equipment is depreciated on a straight-line basis over its estimated useful life ranging from 2 to 18 years. Midstream and Head Office The Company capitalizes all costs that expand the capacity or extend the useful life of the midstream and head office assets. Midstream assets are depreciated on a straight-line basis over their estimated useful lives ranging from 5 to 30 years. Head office assets are depreciated on a declining balance basis. Useful lives The depletion rates and expected useful lives of property, plant and equipment are reviewed on an annual basis, with changes in depletion rates and useful lives accounted for prospectively. Derecognition A property, plant and equipment asset is derecognized upon disposal or when no future economic benefits are expected to arise from the continued use of the asset. Any gain or loss arising on derecognition of the asset (calculated as the difference between the net disposal proceeds and the carrying amount of the asset) is recognized in net earnings within depletion, depreciation and amortization. Major maintenance expenditures Inspection costs associated with major maintenance turnarounds are capitalized and depreciated over the period to the next major maintenance turnaround. All other maintenance costs are expensed as incurred. Impairment The Company assesses property, plant and equipment for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset or group of assets may not be recoverable. Indications of impairment include the existence of low benchmark commodity prices for an extended period of time, significant downward revisions of estimated reserves volumes, significant increases in estimated future development expenditures, or significant adverse changes in the applicable legislative or regulatory frameworks. If an indication of impairment exists, the Company performs an impairment test related to the assets. Individual assets are grouped for impairment assessment purposes into CGUs, which are the lowest level at which there are identifiable cash inflows that are largely independent of the cash inflows of other groups of assets. A CGUs recoverable amount is the higher of its fair value less costs of disposal and its value in use. Where the carrying amount of a CGU exceeds its recoverable amount, the CGU is considered impaired and is written down to its recoverable amount through depletion, depreciation and amortization expense. In subsequent periods, an assessment is made at each reporting date to determine whether there is any indication that previously recognized impairment losses may no longer exist or may have decreased. If such indication exists, the recoverable amount is re-estimated and the net carrying amount of the asset is increased to its revised recoverable amount. The revised recoverable amount cannot exceed the carrying amount that would have been determined, net of depletion, depreciation and amortization, had no impairment loss been recognized for the asset in prior periods. A reversal of impairment is recognized in net earnings. After a reversal, the depletion, depreciation and amortization charge is adjusted in future periods to allocate the asset’s revised carrying amount over its remaining useful life. (G) BUSINESS COMBINATIONS Business combinations are accounted for using the acquisition method. Assets acquired and liabilities assumed in a business combination are recognized at their fair value at the date of the acquisition. Any excess of the consideration paid over the fair value of the net assets acquired is recognized as an asset. Any excess of the fair value of the net assets acquired over the consideration paid is recognized in net earnings. (H) OVERBURDEN REMOVAL COSTS Overburden removal costs incurred during the initial development of a mine at Horizon and AOSP are capitalized to property, plant and equipment. Overburden removal costs incurred during the production of a mine are included in the cost of inventory, unless the overburden removal activity has resulted in a probable inflow of future economic benefits to the Company, in which case the costs are capitalized to property, plant and equipment. Capitalized overburden removal costs are depleted over the life of the mining reserves that directly benefit from the overburden removal activity. (I) CAPITALIZED BORROWING COSTS Borrowing costs attributable to the acquisition, construction or production of qualifying assets are capitalized to the cost of those assets until such time as the assets are substantially available for their intended use. Qualifying assets are comprised of those significant assets that require a period greater than one year to be available for their intended use. All other borrowing costs are recognized in net earnings. (J) LEASES Finance leases, which transfer substantially all of the risks and rewards incidental to ownership of the leased item to the Company, are capitalized at the commencement of the lease term at the fair value of the leased property or, if lower, at the present value of the minimum lease payments. Capitalized leased assets are depreciated over the shorter of the estimated useful life of the asset or the lease term. Operating lease payments are recognized in net earnings over the lease term. (K) ASSET RETIREMENT OBLIGATIONS The Company provides for asset retirement obligations on all of its property, plant and equipment based on current legislation and industry operating practices. Provisions for asset retirement obligations related to property, plant and equipment are recognized as a liability in the period in which they are incurred. Provisions are measured at the present value of management’s best estimate of expenditures required to settle the obligation as at the date of the balance sheets. Subsequent to the initial measurement, the obligation is adjusted to reflect the passage of time, changes in credit adjusted interest rates, and changes in the estimated future cash flows underlying the obligation. The increase in the provision due to the passage of time is recognized as asset retirement obligation accretion expense whereas changes due to discount rates or estimated future cash flows are capitalized to or derecognized from property, plant and equipment. Actual costs incurred upon settlement of the asset retirement obligation are charged against the provision. (L) FOREIGN CURRENCY TRANSLATION Functional and presentation currency Items included in the financial statements of the Company’s subsidiary companies and partnerships are measured using the currency of the primary economic environment in which the subsidiary operates (the “functional currency”). The consolidated financial statements are presented in Canadian dollars, which is the Company’s functional currency. The assets and liabilities of subsidiaries that have a functional currency different from that of the Company are translated into Canadian dollars at the closing rate at the date of the balance sheets, and revenue and expenses are translated at the average rate for the period. Cumulative foreign currency translation adjustments are recognized in other comprehensive income. When the Company disposes of its entire interest in a foreign operation, or loses control, joint control, or significant influence over a foreign operation, the foreign currency gains or losses accumulated in other comprehensive income related to the foreign operation are recognized in net earnings. Transactions and balances Foreign currency transactions are translated into the functional currency of the Company and its subsidiaries and partnerships using the exchange rates prevailing at the dates of the transactions. Foreign exchange gains and losses resulting from the settlement of foreign currency transactions and from the translation at balance sheet date exchange rates of monetary assets and liabilities denominated in currencies other than the functional currency are recognized in net earnings. (M) REVENUE RECOGNITION AND COSTS OF GOODS SOLD Revenue from the sale of crude oil and natural gas is recognized when title passes to the customer, delivery has taken place and collection is reasonably assured. The Company assesses customer creditworthiness, both before entering into contracts and throughout the revenue recognition process. Revenue represents the Company’s share net of royalty payments to governments and other mineral interest owners. Related costs of goods sold are comprised of production, transportation, blending and feedstock, and depletion, depreciation and amortization expenses. These amounts have been separately presented in the consolidated statements of earnings. (N) PRODUCTION SHARING CONTRACTS Production generated from Côte d’Ivoire and Gabon in Offshore Africa is shared under the terms of various Production Sharing Contracts (“PSCs”). Product sales are divided into cost recovery oil and profit oil. Cost recovery oil allows the Company to recover its capital and production costs and the costs carried by the Company on behalf of the respective government state oil companies (the “Governments”). Profit oil is allocated to the joint venture partners in accordance with their respective equity interests, after a portion has been allocated to the Governments. The Governments’ share of profit oil attributable to the Company’s equity interest is allocated to royalty expense and current income tax expense in accordance with the terms of the respective PSCs. (O) INCOME TAX The Company follows the liability method of accounting for income taxes. Under this method, deferred income tax assets and liabilities are recognized based on the estimated income tax effects of temporary differences in the carrying amount of assets and liabilities in the consolidated financial statements and their respective tax bases. Deferred income tax assets and liabilities are calculated using the substantively enacted income tax rates that are expected to apply when the asset or liability is recovered. Deferred income tax assets or liabilities are not recognized when they arise on the initial recognition of an asset or liability in a transaction (other than in a business combination) that, at the time of the transaction, affects neither accounting nor taxable profit. Deferred income tax assets or liabilities are also not recognized on possible future distributions of retained earnings of subsidiaries where the timing of the distribution can be controlled by the Company and it is probable that a distribution will not be made in the foreseeable future, or when distributions can be made without incurring income taxes. Deferred income tax assets for deductible temporary differences and tax loss carryforwards are recognized to the extent that it is probable that future taxable profits will be available against which the temporary differences or tax loss carryforwards can be utilized. The carrying amount of deferred income tax assets is reviewed at each reporting date, and is reduced if it is no longer probable that sufficient future taxable profits will be available against which the temporary differences or tax loss carryforwards can be utilized. Current income tax is calculated based on net earnings for the period, adjusted for items that are non-taxable or taxed in different periods, using income tax rates that are substantively enacted at each reporting date. Income taxes are recognized in net earnings or other comprehensive income, consistent with the items to which they relate. (P) SHARE-BASED COMPENSATION The Company’s Stock Option Plan (the “Option Plan”) provides current employees with the right to elect to receive common shares or a cash payment in exchange for stock options surrendered. The liability for awards granted to employees is initially measured based on the grant date fair value of the awards and the number of awards expected to vest. The awards are re-measured each reporting period for subsequent changes in the fair value of the liability. Fair value is determined using the Black-Scholes valuation model under a graded vesting method. Expected volatility is estimated based on historic results. When stock options are surrendered for cash, the cash settlement paid reduces the outstanding liability. When stock options are exercised for common shares under the Option Plan, consideration paid by the employee and any previously recognized liability associated with the stock options are recorded as share capital. The Company grants Performance Share Units ("PSUs") to certain executive employees. The PSUs are subject to certain performance conditions and vest three years from original grant date. The unamortized costs of employer contributions to the Company’s share bonus program are included in other long-term assets . (Q) FINANCIAL INSTRUMENTS The Company classifies its financial instruments into one of the following categories: financial assets at amortized cost; financial liabilities at amortized cost; and fair value through profit or loss. All financial instruments are measured at fair value on initial recognition. Measurement in subsequent periods is dependent on the classification of the respective financial instrument. Fair value through profit or loss financial instruments are subsequently measured at fair value with changes in fair value recognized in net earnings. All other categories of financial instruments are measured at amortized cost using the effective interest method. Cash and cash equivalents, accounts receivable and certain other long-term assets are classified as financial assets at amortized cost since it is the Company’s intention to hold these assets to maturity and the related cash flows are mainly comprised of payments of principal and interest. Investments in publicly traded shares are classified as fair value through profit or loss. Accounts payable, accrued liabilities, certain other long-term liabilities, and long-term debt are classified as financial liabilities at amortized cost. Risk management assets and liabilities are classified as fair value through profit or loss. Financial assets and liabilities are also categorized using a three-level hierarchy that reflects the significance of the inputs used in making fair value measurements for these assets and liabilities. The fair values of financial assets and liabilities included in Level 1 are determined by reference to quoted prices in active markets for identical assets and liabilities. Fair values of financial assets and liabilities in Level 2 are based on inputs other than Level 1 quoted prices that are observable for the asset or liability either directly (as prices) or indirectly (derived from prices). The fair values of Level 3 financial assets and liabilities are not based on observable market data. The disclosure of the fair value hierarchy excludes financial assets and liabilities where book value approximates fair value due to the liquid nature of the asset or liability. Transaction costs in respect of financial instruments at fair value through profit or loss are recognized in net earnings. Transaction costs in respect of other financial instruments are included in the initial measurement of the financial instrument. Impairment of financial assets At each reporting date, the Company assesses whether there is objective evidence that a financial asset is impaired. If such evidence exists, an impairment loss is recognized. Impairment losses on financial assets carried at amortized cost are calculated as the difference between the amortized cost of the financial asset and the present value of the estimated future cash flows, discounted using the instrument’s original effective interest rate. Impairment losses on financial assets carried at amortized cost are reversed in subsequent periods if the amount of the loss decreases and the decrease can be related objectively to an event occurring after the impairment was recognized. (R) RISK MANAGEMENT ACTIVITIES The Company periodically uses derivative financial instruments to manage its commodity price, foreign currency and interest rate exposures. These financial instruments are entered into solely for hedging purposes and are not used for speculative purposes. All derivative financial instruments are recognized in the consolidated balance sheets at their estimated fair value. The estimated fair value of derivative financial instruments has been determined based on appropriate internal valuation methodologies and/or third party indications. Fair values determined using valuation models require the use of assumptions concerning the amount and timing of future cash flows, discount rates and credit risk. In determining these assumptions, the Company primarily relied on external, readily-observable market inputs including quoted commodity prices and volatility, interest rate yield curves, and foreign exchange rates. The carrying amount of a risk management liability is adjusted for the Company’s own credit risk. The Company documents all derivative financial instruments that are formally designated as hedging transactions at the inception of the hedging relationship, in accordance with the Company’s risk management policies. The effectiveness of the hedging relationship is evaluated, both at inception of the hedge and on an ongoing basis. The Company periodically enters into commodity price contracts to manage anticipated sales and purchases of crude oil and natural gas in order to protect its cash flow for its capital expenditure programs. The effective portion of changes in the fair value of derivative commodity price contracts formally designated as cash flow hedges is initially recognized in other comprehensive income and is reclassified to risk management activities in net earnings in the same period or periods in which the commodity is sold or purchased. The ineffective portion of changes in the fair value of these designated contracts is recognized in risk management activities in net earnings. All changes in the fair value of non-designated crude oil and natural gas commodity price contracts are recognized in risk management activities in net earnings. The Company periodically enters into interest rate swap contracts to manage its fixed to floating interest rate mix on certain of its long-term debt. The interest rate swap contracts require the periodic exchange of payments without the exchange of the notional principal amounts on which the payments are based. Changes in the fair value of interest rate swap contracts designated as fair value hedges and corresponding changes in the fair value of the hedged long-term debt are recognized in interest expense in net earnings. Changes in the fair value of non-designated interest rate swap contracts are recognized in risk management activities in net earnings. Upon termination of an interest rate swap designated as a fair value hedge, the interest rate swap is derecognized in the consolidated balance sheets and the related long-term debt hedged is no longer revalued for subsequent changes in fair value due to interest rates changes. The fair value adjustment due to interest rates on the long-term debt at the date of termination of the interest rate swap is amortized to interest expense over the remaining term of the long-term debt. Cross currency swap contracts are periodically used to manage currency exposure on US dollar denominated long-term debt. The cross currency swap contracts require the periodic exchange of payments with the exchange at maturity of notional principal amounts on which the payments are based. Changes in the fair value of the foreign exchange component of cross currency swap contracts designated as cash flow hedges related to the notional principal amounts are recognized in foreign exchange gains and losses in net earnings. The effective portion of changes in the fair value of the interest rate component of cross currency swap contracts designated as cash flow hedges is initially recognized in other comprehensive income and is reclassified to interest expense when the hedged item is recognized in net earnings, with the ineffective portion recognized in risk management activities in net earnings. Changes in the fair value of non-designated cross currency swap contracts are recognized in risk management activities in net earnings. Realized gains or losses on the termination of financial instruments that have been designated as cash flow hedges are deferred under accumulated other comprehensive income and amortized into net earnings in the periods in which the underlying hedged items are recognized. In the event a designated hedged item is sold, extinguished or matures prior to the termination of the related derivative instrument, any unrealized derivative gain or loss is recognized in net earnings. Realized gains or losses on the termination of financial instruments that have not been designated as hedges are recognized in net earnings. Foreign currency forward contracts are periodically used to manage foreign currency cash requirements. The foreign currency forward contracts involve the purchase or sale of an agreed upon amount of US dollars at a specified future date at forward exchange rates. Changes in the fair value of foreign currency forward contracts designated as cash flow hedges are initially recorded in other comprehensive income and are reclassified to foreign exchange gains and losses when the hedged item is recognized in net earnings. Changes in the fair value of non-designated foreign currency forward contracts are recognized in risk management activities in net earnings. Embedded derivatives are derivatives that are included in a non-derivative host contract. Embedded derivatives are recorded at fair value separately from the host contract when their economic characteristics and risks are not clearly and closely related to the host contract, except when the host contract is an asset. (S) COMPREHENSIVE INCOME Comprehensive income is comprised of the Company’s net earnings and other comprehensive income. Other comprehensive income includes the effective portion of changes in the fair value of derivative financial instruments designated as cash flow hedges and foreign currency translation gains and losses arising from the net investment in foreign operations that do not have a Canadian dollar functional currency. Other comprehensive income is shown net of related income taxes. (T) PER COMMON SHARE AMOUNTS The Company calculates basic earnings per common share by dividing net earnings by the weighted average number of common shares outstanding during the period. As the Company’s Option Plan allows for the settlement of stock options in either cash or shares at the option of the holder, diluted earnings per common share is calculated using the more dilutive of cash settlement or share settlement under the treasury stock method. (U) SHARE CAPITAL Common shares are classified as equity. Costs directly attributable to the issue of new shares or options are included in equity as a deduction from proceeds, net of tax. When the Company acquires its own common shares, share capital is reduced by the average carrying value of the shares purchased. The excess of the purchase price over the average carrying value is recognized as a reduction of retained earnings. Shares are cancelled upon purchase. (V) DIVIDENDS Dividends on common shares are recognized in the Company’s financial statements in the period in which the dividends are declared by the Board of Directors.

ACCOUNTING STANDARDS ISSUED BUT

ACCOUNTING STANDARDS ISSUED BUT NOT YET APPLIED	12 Months Ended
	Dec. 31, 2017
Corporate Information And Statement Of IFRS Compliance [Abstract]
ACCOUNTING STANDARDS ISSUED BUT NOT YET APPLIED	ACCOUNTING STANDARDS ISSUED BUT NOT YET APPLIED In October 2017, the IASB issued amendments to IAS 28 “Investments in Associates and Joint Ventures” to clarify that the impairment provisions in IFRS 9 apply to financial instruments in an associate or joint venture that are not accounted for using the equity method, including long-term interests that form part of the net investment in the associate or joint venture. The amendments are effective January 1, 2019 with earlier adoption permitted. The amendments are required to be adopted retrospectively. The Company is assessing the impact of the amendments on its consolidated financial statements. In June 2017 , the IASB issued IFRIC 23 "Uncertainty over Income Tax Treatments". The interpretation provides guidance on how to reflect the effects of uncertainty in accounting for income taxes where IAS 12 is unclear. The interpretation is effective January 1, 2019 . The Company is assessing the impact of this interpretation on its consolidated financial statements. In January 2016, the IASB issued IFRS 16 “Leases”, which provides guidance on accounting for leases. The new standard replaces IAS 17 “Leases” and related interpretations. IFRS 16 eliminates the distinction between operating leases and financing leases for lessees. The new standard is effective January 1, 2019 with earlier adoption permitted providing that IFRS 15 has been adopted. The new standard is required to be applied retrospectively, with a policy alternative of restating comparative prior periods or recognizing the cumulative adjustment in opening retained earnings at the date of adoption. The Company is assessing the impact of this standard on its consolidated financial statements. IFRS 15 "Revenue from Contracts with Customers" In May 2014, the IASB issued IFRS 15 “Revenue from Contracts with Customers” to provide guidance on the recognition of revenue and cash flows arising from an entity’s contracts with customers, and related disclosures. The new standard replaces several existing standards related to recognition of revenue and states that revenue should be recognized as performance obligations related to the goods or services delivered are settled. IFRS 15 also provides revenue accounting guidance for contract modifications and multiple-element contracts and prescribes additional disclosure requirements. In 2015, the IASB deferred the effective date for the new standard to January 1, 2018. The new standard is required to be adopted retrospectively, with earlier adoption permitted. Effective January 1, 2018, the Company retrospectively adopted IFRS 15. Adoption of the new standard did not have a significant impact on the Company’s recognition and measurement of revenue; however, it will require certain additional disclosures. Upon adoption of IFRS 15, the Company applied the practical expedient such that contracts that were completed in the comparative periods have not been restated. IFRS 9 "Financial Instruments" Effective January 1, 2014, the Company adopted the version of IFRS 9 “Financial Instruments” issued November 2013. In July 2014, the IASB issued amendments to IFRS 9 to include accounting guidance to assess and recognize impairment losses on financial assets based on an expected loss model. The amendments are effective January 1, 2018 and are required to be adopted retrospectively. Effective January 1, 2018, the Company adopted the amendment to IFRS 9 and elected to apply the limited exemption in IFRS 9 relating to transition for impairment. Adoption of the amendment did not have a significant impact on the Company’s previous accounting for impairment of financial assets.

CRITICAL ACCOUNTING ESTIMATES A

CRITICAL ACCOUNTING ESTIMATES AND JUDGEMENTS	12 Months Ended
	Dec. 31, 2017
Corporate Information And Statement Of IFRS Compliance [Abstract]
CRITICAL ACCOUNTING ESTIMATES AND JUDGEMENTS	CRITICAL ACCOUNTING ESTIMATES AND JUDGEMENTS The Company has made estimates, assumptions and judgements regarding certain assets, liabilities, revenues and expenses in the preparation of the consolidated financial statements, primarily related to unsettled transactions and events as of the date of the consolidated financial statements. Accordingly, actual results may differ from estimated amounts. The estimates, assumptions and judgements that have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year are addressed below. (A) Crude Oil and Natural Gas Reserves Purchase price allocations, depletion, depreciation and amortization, asset retirement obligations, and amounts used in impairment calculations are based on estimates of crude oil and natural gas reserves. Reserves estimates are based on engineering data, estimated future prices and production costs, expected future rates of production, and the timing and amount of future development expenditures, all of which are subject to many uncertainties, interpretations and judgements. The Company expects that, over time, its reserves estimates will be revised upward or downward based on updated information. (B) Asset Retirement Obligations The Company provides for asset retirement obligations on its property, plant and equipment based on current legislation and operating practices. Estimated future costs include assumptions of dates of future abandonment and technological advances and estimates of future inflation rates and discount rates. Actual costs may vary from the estimated provision due to changes in environmental legislation, the impact of inflation, changes in technology, changes in operating practices, and changes in the date of abandonment due to changes in reserves life. These differences may have a material impact on the estimated provision. (C) Income Taxes The Company is subject to income taxes in numerous legal jurisdictions. Accounting for income taxes requires the Company to interpret frequently changing laws and regulations, including changing income tax rates, and make certain judgements with respect to the application of tax law, estimating the timing of temporary difference reversals, and estimating the realizability of tax assets. There are many transactions and calculations for which the ultimate tax determination is uncertain. The Company recognizes a liability for a tax filing position based on its assessment of the probability that additional taxes may ultimately be due. (D) Fair Value of Derivatives and Other Financial Instruments The fair value of financial instruments that are not traded in an active market is determined using valuation techniques. The Company uses its judgement to select a variety of methods and make assumptions that are primarily based on market conditions existing at the end of each reporting period. The Company uses directly and indirectly observable inputs in measuring the value of financial instruments that are not traded in active markets, including quoted commodity prices and volatility, interest rate yield curves and foreign exchange rates. (E) Purchase Price Allocations Purchase prices related to business combinations are allocated to the underlying acquired assets and liabilities based on their estimated fair value at the time of acquisition. The determination of fair value requires the Company to make estimates, assumptions and judgements regarding future events. The allocation process is inherently subjective and impacts the amounts assigned to individually identifiable assets and liabilities, including the fair value of crude oil and natural gas properties together with deferred income tax effects. As a result, the purchase price allocation impacts the Company’s reported assets and liabilities and future net earnings due to the impact on future depletion, depreciation, and amortization expense and impairment tests. (F) Share-Based Compensation The Company has made various assumptions in estimating the fair values of stock options granted under its Option Plan, including expected volatility, expected exercise timing and future forfeiture rates. At each period end, stock options outstanding are remeasured for changes in the fair value of the liability. (G) Identification of CGUs CGUs are defined as the lowest grouping of integrated assets that generate identifiable cash inflows that are largely independent of the cash inflows of other assets or groups of assets. The classification of assets into CGUs requires significant judgement and interpretations with respect to the integration between assets, the existence of active markets, shared infrastructures, and the way in which management monitors the Company’s operations. (H) Impairment of Assets The recoverable amount of a CGU or an individual asset has been determined as the higher of the CGUs' or the asset’s fair value less costs of disposal and its value in use. These calculations require the use of estimates and assumptions and are subject to change as new information becomes available, including information on future commodity prices, expected production volumes, quantity of reserves, asset retirement obligations, future development and operating costs, after-tax discount rates currently ranging from 10% to 12% , and income taxes. Changes in assumptions used in determining the recoverable amount could affect the carrying value of the related assets and CGUs. (I) Contingencies Contingencies are subject to measurement uncertainty as the related financial impact will only be confirmed by the outcome of a future event. The assessment of contingencies requires the application of judgements and estimates including the determination of whether a present obligation exists and the reliable estimation of the timing and amount of cash flows required to settle the contingency.

INVENTORY

INVENTORY	12 Months Ended
	Dec. 31, 2017
Inventories [Abstract]
INVENTORY	INVENTORY 2017 2016 Product inventory $ 285 $ 263 Materials and supplies 609 426 $ 894 $ 689 The Company recorded a write-down of its product inventory of $33 million from cost to net realizable value as at December 31, 2017 ( 2016 - $73 million ).

EXPLORATION AND EVALUATION ASSE

EXPLORATION AND EVALUATION ASSETS	12 Months Ended
	Dec. 31, 2017
Exploration For And Evaluation Of Mineral Resources [Abstract]
EXPLORATION AND EVALUATION ASSETS	EXPLORATION AND EVALUATION ASSETS Exploration and Production Oil Sands Mining and Upgrading Total North America North Sea Offshore Africa Cost At December 31, 2015 $ 2,500 $ — $ 86 $ — $ 2,586 Additions 20 — 9 — 29 Transfers to property, plant and equipment (211 ) — — — (211 ) Disposals/derecognitions (3 ) — (18 ) — (21 ) Foreign exchange adjustments — — (1 ) — (1 ) At December 31, 2016 2,306 — 76 — 2,382 Additions 144 — 15 — 159 Acquisition of AOSP and other assets (note 7) 31 — — 259 290 Transfers to property, plant and equipment (198 ) — — — (198 ) Disposals/derecognitions (1 ) — — — (1 ) At December 31, 2017 $ 2,282 $ — $ 91 $ 259 $ 2,632 On May 31, 2017, the Company completed the acquisition of AOSP and other assets in the Oil Sands Mining and Upgrading and North America Exploration and Production segments, including exploration and evaluation assets of $290 million . Refer to note 7 regarding the acquisition of AOSP and other assets. During 2017, the Company disposed of a number of North America exploration and evaluation assets with a net book value $1 million for consideration of $36 million , resulting in a pre-tax gain on sale of properties of $35 million . During 2016, the Company disposed of a number of North America exploration and evaluation assets totaling $3 million for consideration of $35 million , resulting in a pre-tax gain on sale of properties of $32 million . In addition, in connection with the Company's notice of withdrawal from Block CI-12 in Côte d'Ivoire, Offshore Africa, the Company derecognized $18 million of exploration and evaluation assets.

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Dec. 31, 2017
Property, plant and equipment [abstract]
PROPERTY, PLANT AND EQUIPMENT	PROPERTY, PLANT AND EQUIPMENT Exploration and Production Oil Sands Mining and Upgrading Midstream Head Office Total North America North Sea Offshore Africa Cost At December 31, 2015 $ 60,540 $ 7,414 $ 5,173 $ 24,343 $ 577 $ 378 $ 98,425 Additions 1,462 186 116 2,822 6 17 4,609 Transfers from E&E assets 211 — — — — — 211 Disposals/derecognitions (566 ) — — (127 ) (349 ) — (1,042 ) Foreign exchange adjustments and other — (220 ) (157 ) — — — (377 ) At December 31, 2016 61,647 7,380 5,132 27,038 234 395 101,826 Additions (1) 3,003 255 101 1,660 194 19 5,232 Acquisition of AOSP and other assets (note 7) 349 — — 13,832 — — 14,181 Transfers from E&E assets 198 — — — — — 198 Disposals/derecognitions (381 ) — — (446 ) — — (827 ) Foreign exchange adjustments and other — (509 ) (352 ) — — — (861 ) At December 31, 2017 $ 64,816 $ 7,126 $ 4,881 $ 42,084 $ 428 $ 414 $ 119,749 Accumulated depletion and depreciation At December 31, 2015 $ 35,347 $ 5,264 $ 3,659 $ 2,294 $ 132 $ 254 $ 46,950 Expense 3,440 457 243 662 11 27 4,840 Disposals/derecognitions (486 ) — — (127 ) (28 ) — (641 ) Foreign exchange adjustments and other 10 (137 ) (105 ) (1 ) — — (233 ) At December 31, 2016 38,311 5,584 3,797 2,828 115 281 50,916 Expense 3,220 509 205 1,220 9 23 5,186 Disposals/derecognitions (381 ) — — (446 ) — — (827 ) Foreign exchange adjustments and other 1 (440 ) (283 ) 26 — — (696 ) At December 31, 2017 $ 41,151 $ 5,653 $ 3,719 $ 3,628 $ 124 $ 304 $ 54,579 Net book value - at December 31, 2017 $ 23,665 $ 1,473 $ 1,162 $ 38,456 $ 304 $ 110 $ 65,170 - at December 31, 2016 $ 23,336 $ 1,796 $ 1,335 $ 24,210 $ 119 $ 114 $ 50,910 (1) Additions in Midstream include the revaluation of a previously held joint interest in certain pipeline system assets. Project costs not subject to depletion and depreciation 2017 2016 Kirby Thermal Oil Sands – North $ 944 $ 846 On May 31, 2017, the Company completed the acquisition of AOSP and other assets in the Oil Sands Mining and Upgrading and North America Exploration and Production segments, including property, plant and equipment of $14,181 million . Refer to note 7 regarding the acquisition of AOSP and other assets. During 2017 , the Company acquired a number of other producing crude oil and natural gas properties in the North America Exploration and Production segment, including exploration and evaluation assets of $27 million ( 2016 - $nil ; 2015 - $37 million ), along with the remaining interest in certain pipeline system assets in the Midstream segment, for net cash consideration of $1,013 million ( 2016 – $159 million ; 2015 – $406 million ). These transactions were accounted for using the acquisition method of accounting. In connection with these acquisitions, the Company assumed associated asset retirement obligations of $63 million ( 2016 – $30 million ; 2015 – $133 million ). No net deferred income tax liabilities were recognized on these acquisitions (2016 - $nil ; 2015 - $nil ). Further, in connection with the acquisition of pipeline system assets in the Midstream segment, the Company recognized a pre-tax revaluatio n gain o f $114 million ( $83 million after-tax) related to a previously held joint interest in the pipeline. During 2016, in the Midstream segment, the Company disposed of its interest in the Cold Lake Pipeline, comprising $321 million of property, plant and equipment for total net consideration of $539 million , resulting in a pre and after-tax gain of $218 million . Total net consideration was comprised of $349 million in cash, together with $190 million of non-cash share consideration of approximately 6.4 million common shares of Inter Pipeline Ltd. (“Inter Pipeline”) with a value of $29.57 per common share, determined as of the closing date. As at December 31, 2017 , the Company assessed the recoverability of its property, plant and equipment and its exploration and evaluation assets, and determined the carrying amounts to be recoverable. The Company capitalizes construction period interest for qualifying assets based on costs incurred and the Company’s cost of borrowing. Interest capitalization to a qualifying asset ceases once the asset is substantially available for its intended use. During 2017 , pre-tax interest of $82 million ( 2016 – $ 233 million ; 2015 – $244 million ) was capitalized to property, plant and equipment using a weighted average capitalization rate of 3.8% ( 2016 – 3.9% ; 2015 – 3.9% ).

ACQUISITION OF INTERESTS IN THE

ACQUISITION OF INTERESTS IN THE ATHABASCA OIL SANDS PROJECT AND OTHER ASSETS	12 Months Ended
	Dec. 31, 2017
Business Combinations1 [Abstract]
ACQUISITION OF INTERESTS IN THE ATHABASCA OIL SANDS PROJECT AND OTHER ASSETS	ACQUISITION OF INTERESTS IN THE ATHABASCA OIL SANDS PROJECT AND OTHER ASSETS On May 31, 2017, the Company completed the acquisition of a direct and indirect 70% interest in AOSP from Shell Canada Limited and certain subsidiaries (“Shell”) and an affiliate of Marathon Oil Corporation (“Marathon"), including a 70% interest in the mining and extraction operations north of Fort McMurray, Alberta, 70% of the Scotford Upgrader and Quest Carbon Capture and Storage ("CCS") project, and a 100% working interest in the Peace River thermal in situ operations and Cliffdale heavy oil field, as well as other oil sands leases. The Company also assumed certain pipeline and other commitments (see note 19). The Company consolidates its direct and indirect interest in the assets, liabilities, revenue and expenses of AOSP and other assets in proportion to the Company’s interests. Total purchase consideration of $12,541 million , subject to closing adjustments, was comprised of cash payments of $8,217 million , approximately 97.6 million common shares of the Company issued to Shell with a fair value of approximately $3,818 million , and deferred purchase consideration of $506 million (US $375 million ) payable to Marathon in March 2018. The fair value of the Company's common shares was determined using the market price of the shares as at the acquisition date. In connection with the acquisition of AOSP and other assets, the Company arranged acquisition financing of $1.8 billion of medium-term notes in Canada, US$3 billion of long-term notes in the United States and a $3 billion non-revolving term loan facility (see note 10). The acquisition has been accounted for as a business combination using the acquisition method of accounting. The allocation of the purchase price was based on management's best estimates of the fair value of the assets and liabilities acquired as at the acquisition date. Key assumptions used in the determination of estimated fair value were future commodity prices, expected production volumes, quantity of reserves, asset retirement obligations, future development and operating costs, discount rates, income taxes and foreign exchange rates. The fair value of accounts receivable, inventory, accounts payable and accrued liabilities approximated their carrying values due to the liquid nature of the assets and liabilities. The following provides a summary of the net assets acquired and (liabilities) assumed relating to the acquisition: Cash $ 93 Other working capital 291 Property, plant and equipment 14,181 Exploration and evaluation assets 290 Asset retirement obligations (721 ) Other long-term liabilities (73 ) Deferred income taxes (1,287 ) Net assets acquired $ 12,774 Total purchase consideration 12,541 Gain on acquisition before transaction costs $ 233 The Company recognized a gain of $230 million , net of transaction costs of $3 million , representing the excess of the fair value of the net assets acquired compared to total purchase consideration. The above amounts are estimates, and may be subject to change based on the receipt of new information. As a result of the acquisitions, revenue increased by $2,872 million to $16,651 million and net operating income (comprised of revenue less production, and transportation, blending, and feedstock expense) increased by $1,166 million to $8,138 million for the year ended December 31, 2017 . If the acquisitions had occurred on January 1, 2017, the Company estimates that pro forma revenue would have increased by $2,181 million to $18,832 million and pro forma net operating income would have increased by $735 million to $8,873 million for the year ended December 31, 2017 . Readers are cautioned that pro forma revenue and pro forma net operating income are not necessarily indicative of the results of operations that would have resulted had the acquisition actually occurred on January 1, 2017 , or of future results. Actual results would have been different and those differences may have been material in comparison to the pro forma information provided. Pro forma results are based on available historical information for the assets as provided to the Company and do not include any synergies that have arisen subsequent to the acquisition date.

INVESTMENTS

INVESTMENTS	12 Months Ended
	Dec. 31, 2017
Financial Instruments [Abstract]
INVESTMENTS	INVESTMENTS As at December 31, 2017 and 2016 , the Company had the following investments: 2017 2016 Investment in PrairieSky Royalty Ltd. $ 726 $ 723 Investment in Inter Pipeline Ltd. 167 190 $ 893 $ 913 Investment in PrairieSky Royalty Ltd. During 2015 , as partial consideration for the disposal of a number of North America royalty income assets, the Company received non-cash share consideration of $985 million , comprised of approximately 44.4 million common shares of PrairieSky Royalty Ltd. ("PrairieSky") at $22.16 per common share determined as of the closing date. PrairieSky is in the business of acquiring and managing oil and gas royalty income assets through indirect third-party oil and gas development. During 2016, the Company completed the net distribution of approximately 21.8 million PrairieSky common shares to the shareholders of record of the Company as at June 3, 2016, completing the previously announced Plan of Arrangement. The distribution was recognized as a return of capital of $546 million . Subsequent to the distribution, the Company’s ownership interest in PrairieSky was less than 10% of the issued and outstanding common shares of PrairieSky. The Company’s investment of 22.6 million common shares does not constitute significant influence, and is accounted for at fair value through profit or loss, remeasured at each reporting date. As at December 31, 2017 , the Company’s investment in PrairieSky was classified as a current asset. The (gain) loss from the investment in PrairieSky was comprised as follows: 2017 2016 2015 Fair value (gain) loss from PrairieSky $ (3 ) $ (292 ) $ 11 Dividend income from PrairieSky (17 ) (27 ) (5 ) $ (20 ) $ (319 ) $ 6 Investment in Inter Pipeline Ltd. During 2016, as partial consideration for the disposal of the Company's interest in the Cold Lake Pipeline, the Company received non-cash share consideration of $190 million , comprised of approximately 6.4 million common shares of Inter Pipeline Ltd. ("Inter Pipeline") at $29.57 per common share determined as of the closing date. Inter Pipeline is in the business of petroleum transportation, natural gas liquids processing, and bulk liquid storage in Western Canada and Europe. The Company's investment of 6.4 million common shares of Inter Pipeline does not constitute significant influence, and is accounted for at fair value through profit or loss, remeasured at each reporting date. As at December 31, 2017 , the Company's investment in Inter Pipeline was classified as a current asset. The loss (gain) from the investment in Inter Pipeline was comprised as follows: 2017 2016 2015 Fair value loss from Inter Pipeline $ 23 $ — $ — Dividend income from Inter Pipeline (10 ) (1 ) — $ 13 $ (1 ) $ —

OTHER LONG-TERM ASSETS

OTHER LONG-TERM ASSETS	12 Months Ended
	Dec. 31, 2017
Subclassifications of assets, liabilities and equities [abstract]
OTHER LONG-TERM ASSETS	OTHER LONG-TERM ASSETS 2017 2016 Investment in North West Redwater Partnership $ 292 $ 261 North West Redwater Partnership subordinated debt (1) 510 385 Risk Management (note 18) 204 489 Other 241 168 1,247 1,303 Less: current portion 79 283 $ 1,168 $ 1,020 (1) Includes accrued interest. Investment in North West Redwater Partnership The Company's 50% interest in Redwater Partnership is accounted for using the equity method based on Redwater Partnership’s voting and decision-making structure and legal form. Redwater Partnership has entered into agreements to construct and operate a 50,000 barrel per day bitumen upgrader and refinery (the "Project") under processing agreements that target to process 12,500 barrels per day of bitumen feedstock for the Company and 37,500 barrels per day of bitumen feedstock for the Alberta Petroleum Marketing Commission (“APMC”), an agent of the Government of Alberta, under a 30 year fee-for-service tolling agreement. The facility capital cost ("FCC") budget for the Project is currently estimated to be $9,500 million with project completion targeted for third quarter 2018 . Productivity challenges during construction have continued to result in upward budgetary pressures that may result in a further increase in FCC of up to 2% . During 2013 , the Company and APMC agreed, each with a 50% interest, to provide subordinated debt, bearing interest at prime plus 6% , as required for Project costs to reflect an agreed debt to equity ratio of 80/20. To December 31, 2017 , each party has provided $411 million of subordinated debt, together with accrued interest thereon of $99 million , for a Company total of $510 million . Any additional subordinated debt financing is not expected to be significant. Under its processing agreement, beginning on the earlier of the commercial operations date of the refinery and June 1, 2018 , the Company is unconditionally obligated to pay its 25% pro rata share of the debt portion of the monthly cost of service toll, including interest, fees and principal repayments, of the syndicated credit facility and bonds, over the tolling period of 30 years. During 2017 , Redwater Partnership issued $750 million of 2.80% series J senior secured bonds due June 2027 and $750 million of 3.65% series K senior secured bonds due June 2035 . During 2016 , Redwater Partnership issued $550 million of 4.25% series F senior secured bonds due June 2029 , $500 million of 4.75% series G senior secured bonds due June 2037 , $500 million of 4.15% series H senior secured bonds due June 2033 , and $500 million of 4.35% series I senior secured bonds due January 2039 . As at December 31, 2017 , Redwater Partnership had additional borrowings of $1,870 million under its secured $3,500 million syndicated credit facility, maturing June 2018. Subsequent to December 31, 2017, Redwater Partnership extended $2,000 million of the $3,500 revolving syndicated credit facility to June 2021. The remaining $1,500 million was extended on a fully drawn non-revolving basis maturing February 2020. The assets, liabilities, partners’ equity and equity income related to Redwater Partnership and the Company’s 50% interest at December 31, 2017 and 2016 were comprised as follows: 2017 2016 Redwater Partnership Company Redwater Partnership Company Current assets $ 330 $ 165 $ 96 $ 48 Non-current assets $ 10,540 $ 5,270 $ 8,258 $ 4,129 Current liabilities $ 2,476 $ 1,238 $ 572 $ 286 Non-current liabilities $ 7,810 $ 3,905 $ 7,260 $ 3,630 Partners’ equity $ 584 $ 292 $ 522 $ 261 Equity income $ (62 ) $ (31 ) $ (14 ) $ (7 )

LONG-TERM DEBT

LONG-TERM DEBT	12 Months Ended
	Dec. 31, 2017
Financial Instruments [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT 2017 2016 Canadian dollar denominated debt, unsecured Bank credit facilities $ 3,544 $ 2,758 Medium-term notes 3.05% debentures due June 19, 2019 500 500 2.60% debentures due December 3, 2019 500 500 2.05% debentures due June 1, 2020 900 — 2.89% debentures due August 14, 2020 1,000 1,000 3.31% debentures due February 11, 2022 1,000 1,000 3.55% debentures due June 3, 2024 500 500 3.42% debentures due December 1, 2026 600 — 4.85% debentures due May 30, 2047 300 — 8,844 6,258 US dollar denominated debt, unsecured Bank credit facilities (December 31, 2017 - US$1,839 million; 2,300 1,213 Commercial paper (December 31, 2017 - US$500 million; December 31, 2016 - US$250 million) 625 336 US dollar debt securities 5.70% due May 15, 2017 (US$1,100 million) — 1,477 1.75% due January 15, 2018 (US$600 million) 751 806 5.90% due February 1, 2018 (US$400 million) 501 537 3.45% due November 15, 2021 (US$500 million) 625 671 2.95% due January 15, 2023 (US$1,000 million) 1,252 — 3.80% due April 15, 2024 (US$500 million) 625 671 3.90% due February 1, 2025 (US$600 million) 751 806 3.85% due June 1, 2027 (US$1,250 million) 1,566 — 7.20% due January 15, 2032 (US$400 million) 501 537 6.45% due June 30, 2033 (US$350 million) 438 470 5.85% due February 1, 2035 (US$350 million) 438 470 6.50% due February 15, 2037 (US$450 million) 563 604 6.25% due March 15, 2038 (US$1,100 million) 1,377 1,477 6.75% due February 1, 2039 (US$400 million) 501 537 4.95% due June 1, 2047 (US$750 million) 939 — 13,753 10,612 Long-term debt before transaction costs and original issue discounts, net 22,597 16,870 Less: original issue discounts, net (1) 18 10 transaction costs (1) (2) 121 55 22,458 16,805 Less: current portion of commercial paper 625 336 current portion of other long-term debt (1) (2) 1,252 1,476 $ 20,581 $ 14,993 (1) The Company has included unamortized original issue discounts and premiums, and directly attributable transaction costs in the carrying amount of the outstanding debt. (2) Transaction costs primarily represent underwriting commissions charged as a percentage of the related debt offerings, as well as legal, rating agency and other professional fees. Bank Credit Facilities and Commercial Paper As at December 31, 2017 , the Company had in place bank credit facilities of $11,050 million , as described below, of which $4,112 million was available. This excludes certain other dedicated credit facilities supporting letters of credit. • a $100 million demand credit facility; • a $750 million non-revolving term credit facility maturing February 2019 ; • a $125 million non-revolving term credit facility maturing February 2019 ; • a $2,200 million non-revolving term credit facility maturing October 2019 ; • a $ 3,000 million non-revolving term credit facility maturing May 2020 ; • a $ 2,425 million revolving syndicated credit facility maturing June 2020 ; • a $ 2,425 million revolving syndicated credit facility with $330 million maturing in June 2019 and $2,095 million maturing June 2021 ; and • a £15 million demand credit facility related to the Company’s North Sea operations. During 2017 , the Company extended $2,095 million of the $2,425 million revolving syndicated credit facility originally due June 2019 to June 2021 . The remaining $330 million outstanding under this facility continues under the previous terms and matures in June 2019. The other $2,425 million revolving credit facility matures in June 2020 . The revolving credit facilities are extendible annually at the mutual agreement of the Company and the lenders. If the facilities are not extended, the full amount of the outstanding principal would be repayable on the maturity date. Borrowings under these facilities may be made by way of pricing referenced to Canadian dollar or US dollar bankers’ acceptances, or LIBOR, US base rate or Canadian prime loans. During 2017, the $1,500 million non-revolving term credit facility was increased to $2,200 million and the maturity date was extended to October 2019 from April 2018. Borrowings under the $2,200 million non-revolving credit facility may be made by way of pricing referenced to Canadian dollar or US dollar bankers’ acceptances, or LIBOR, US base rate or Canadian prime loans. As at December 31, 2017 , the $2,200 million facility was fully drawn. Borrowings under the $750 million and $125 million non-revolving term credit facilities may be made by way of pricing referenced to Canadian dollar bankers’ acceptances or Canadian prime loans. As at December 31, 2017 , the $750 million and $125 million facilities were each fully drawn. Subsequent to December 31, 2017, the Company extended the $750 million non-revolving term credit facility originally due February 2019 to February 2021 and fully repaid and cancelled the $125 million non-revolving term credit facility. In addition to the credit facilities described above, during 2017 the Company entered into a $3,000 million non-revolving term loan facility to finance the acquisition of AOSP and other assets. This facility matures in May 2020 and is subject to annual amortization of 5% of the original balance. Borrowings under the term loan facility may be made by way of pricing referenced to Canadian dollar or US dollar bankers’ acceptances, or LIBOR, US base rate or Canadian prime loans. The facility also supports a US$375 million letter of credit relating to the deferred purchase consideration payable to Marathon in March 2018. As at December 31, 2017 , the $3,000 million facility was fully drawn. Subsequent to December 31, 2017, the Company repaid and cancelled $150 million of the facility; $2,850 million remains outstanding. The Company’s borrowings under its US commercial paper program are authorized up to a maximum US$2,500 million . The Company reserves capacity under its bank credit facilities for amounts outstanding under this program. The Company’s weighted average interest rate on bank credit facilities and commercial paper outstanding as at December 31, 2017 was 2.2% ( December 31, 2016 – 1.9% ), and on total long-term debt outstanding for the year ended December 31, 2017 was 3.8% ( December 31, 2016 – 3.9% ). At December 31, 2017 , letters of credit and guarantees aggregating $866 million were outstanding, including letters of credit of $651 million related to AOSP (including the deferred purchase consideration payable to Marathon in March 2018), a $39 million financial guarantee related to Horizon and $63 million of letters of credit related to North Sea operations. Medium-Term Notes During 2017, the Company issued $900 million of 2.05% medium-term notes due June 2020 , $600 million of 3.42% medium-term notes due December 2026 and $300 million of 4.85% medium-term notes due May 2047 . Proceeds from the securities were used to finance the acquisition of AOSP and other assets. In July 2017 , the Company filed a new base shelf prospectus that allows for the offer for sale from time to time of up to $3,000 million of medium-term notes in Canada, which expires in August 2019 . If issued, these securities may be offered in amounts and at prices, including interest rates, to be determined based on market conditions at the time of issuance. During 2016, the Company issued $1,000 million of 3.31% medium-term notes due February 2022 . US Dollar Debt Securities During 2017, the Company repaid US$1,100 million of 5.70% notes, and issued US$1,000 million of 2.95% notes due January 2023 , US$1,250 million of 3.85% notes due June 2027 and US$750 million of 4.95% notes due June 2047 . Proceeds from the debt securities were used to finance the acquisition of AOSP and other assets. In July 2017 , the Company filed a new base shelf prospectus that allows for the offer for sale from time to time of up to US$3,000 million of debt securities in the United States, which expires in August 2019 . If issued, these securities may be offered in amounts and at prices, including interest rates, to be determined based on market conditions at the time of issuance. Subsequent to December 31, 2017, the Company repaid US$600 million of 1.75% notes and US$400 million of 5.90% notes. During 2016, the Company repaid US$500 million of three-month LIBOR plus 0.375% notes and US$250 million of 6.00% notes. Scheduled Debt Repayments Scheduled debt repayments are as follows: Year Repayment 2018 $ 2,027 2019 $ 4,228 2020 $ 4,231 2021 $ 760 2022 $ 1,000 Thereafter $ 10,351

OTHER LONG-TERM LIABILITIES

OTHER LONG-TERM LIABILITIES	12 Months Ended
	Dec. 31, 2017
Subclassifications of assets, liabilities and equities [abstract]
OTHER LONG-TERM LIABILITIES	OTHER LONG-TERM LIABILITIES 2017 2016 Asset retirement obligations $ 4,327 $ 3,243 Share-based compensation 414 426 Risk management (note 18) 103 — Other (1) 565 17 5,409 3,686 Less: current portion 1,012 463 $ 4,397 $ 3,223 (1) Included in Other at December 31, 2017 is $469 million ( US$375 million ) of deferred purchase consideration payable to Marathon in March 2018. Asset Retirement Obligations The Company’s asset retirement obligations are expected to be settled on an ongoing basis over a period of approximately 60 years and have been discounted using a weighted average discount rate of 4.7% ( 2016 – 5.2% ; 2015 – 5.9% ). Reconciliations of the discounted asset retirement obligations were as follows: 2017 2016 2015 Balance – beginning of year $ 3,243 $ 2,950 $ 4,221 Liabilities incurred 12 3 7 Liabilities acquired, net 784 30 129 Liabilities settled (274 ) (267 ) (370 ) Asset retirement obligation accretion 164 142 173 Revision of cost, inflation rates and timing estimates (40 ) (68 ) (313 ) Change in discount rate 509 493 (1,150 ) Foreign exchange adjustments (71 ) (40 ) 253 Balance – end of year 4,327 3,243 2,950 Less: current portion 92 95 101 $ 4,235 $ 3,148 $ 2,849 Segmented Asset Retirement Obligations 2017 2016 Exploration and Production North America $ 1,840 $ 1,444 North Sea 755 837 Offshore Africa 245 244 Oil Sands Mining and Upgrading 1,486 717 Midstream 1 1 $ 4,327 $ 3,243 Share-Based Compensation As the Company’s Option Plan provides current employees with the right to elect to receive common shares or a cash payment in exchange for stock options surrendered, a liability for potential cash settlements is recognized. The current portion represents the maximum amount of the liability payable within the next twelve month period if all vested stock options are surrendered for cash settlement. 2017 2016 2015 Balance – beginning of year $ 426 $ 128 $ 203 Share-based compensation expense (recovery) 134 355 (46 ) Cash payment for stock options surrendered (6 ) (7 ) (1 ) Transferred to common shares (154 ) (117 ) (18 ) Charged to (recovered from) Oil Sands Mining and Upgrading, net 14 67 (10 ) Balance – end of year 414 426 128 Less: current portion 348 368 105 $ 66 $ 58 $ 23 Included within share-based compensation expense for the year ended December 31, 2017 was $5 million (2016 – $nil ; 2015 – $nil ) related to PSUs granted to certain executive employees. The fair value of stock options outstanding was estimated using the Black-Scholes valuation model with the following weighted average assumptions: 2017 2016 2015 Fair value $ 11.82 $ 11.41 $ 3.06 Share price $ 44.92 $ 42.79 $ 30.22 Expected volatility 27.1% 30.7% 28.6% Expected dividend yield 2.5% 2.3% 3.0% Risk free interest rate 1.8% 0.9% 0.6% Expected forfeiture rate 5.0% 5.0% 4.8% Expected stock option life (1) 4.5 years 4.6 years 4.5 years (1) At original time of grant. The intrinsic value of vested stock options at December 31, 2017 was $195 million ( 2016 – $191 million ; 2015 – $10 million ).

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2017
Income Taxes [Abstract]
INCOME TAXES	INCOME TAXES The provision for income tax was as follows: Expense (recovery) 2017 2016 2015 Current corporate income tax – North America $ (145 ) $ (377 ) $ 86 Current corporate income tax – North Sea 57 (74 ) (117 ) Current corporate income tax – Offshore Africa 45 22 17 Current PRT (1) – North Sea (132 ) (198 ) (258 ) Other taxes 11 9 11 Current income tax (164 ) (618 ) (261 ) Deferred corporate income tax 586 (106 ) 216 Deferred PRT (1) – North Sea 54 (135 ) 15 Deferred income tax 640 (241 ) 231 Income tax $ 476 $ (859 ) $ (30 ) (1) Petroleum Revenue Tax. The provision for income tax is different from the amount computed by applying the combined statutory Canadian federal and provincial income tax rates to earnings (loss) before taxes. The reasons for the difference are as follows: 2017 2016 2015 Canadian statutory income tax rate 27.0% 27.0% 26.0% Income tax provision at statutory rate $ 776 $ (287 ) $ (173 ) Effect on income taxes of: UK PRT and other taxes (67 ) (324 ) (232 ) Impact of deductible UK PRT and other taxes on corporate income tax 28 131 119 Foreign and domestic tax rate differentials (43 ) (54 ) (157 ) Non-taxable portion of capital gains/losses (86 ) (80 ) 36 Stock options exercised for common shares 33 94 (12 ) Income tax rate and other legislative changes 10 (107 ) 362 Non-taxable gain on corporate acquisitions (63 ) — — Revisions arising from prior year tax filings (3 ) (120 ) 32 Change in unrecognized capital loss carryforward asset (86 ) (80 ) 36 Other (23 ) (32 ) (41 ) Income tax expense (recovery) $ 476 $ (859 ) $ (30 ) The following table summarizes the temporary differences that give rise to the net deferred income tax liability: 2017 2016 Deferred income tax liabilities Property, plant and equipment and exploration and evaluation assets $ 12,484 $ 10,259 Unrealized risk management activities 20 62 PRT deduction for corporate income tax 7 29 Investments 96 98 Investment in North West Redwater Partnership 252 222 12,859 10,670 Deferred income tax assets Asset retirement obligations (1,264 ) (983 ) Loss carryforwards (523 ) (390 ) Unrealized foreign exchange loss on long-term debt (29 ) (149 ) Deferred PRT (18 ) (73 ) Other (50 ) (2 ) (1,884 ) (1,597 ) Net deferred income tax liability $ 10,975 $ 9,073 Movements in deferred tax assets and liabilities recognized in net earnings during the year were as follows: 2017 2016 2015 Property, plant and equipment and exploration and evaluation assets $ 541 $ 37 $ (7 ) Timing of partnership items — (261 ) (176 ) Unrealized foreign exchange loss (gain) on long-term debt 120 63 (222 ) Unrealized risk management activities (46 ) (44 ) (5 ) Asset retirement obligations (88 ) (20 ) 522 Loss carryforwards 48 (221 ) (53 ) Investments (2 ) 38 60 Investment in North West Redwater Partnership 30 81 106 Deferred PRT 54 (135 ) 15 PRT deduction for corporate income tax (21 ) 61 (5 ) Other 4 160 (4 ) $ 640 $ (241 ) $ 231 The following table summarizes the movements of the net deferred income tax liability during the year: 2017 2016 2015 Balance – beginning of year $ 9,073 $ 9,344 $ 8,970 Deferred income tax expense (recovery) 640 (241 ) 231 Deferred income tax expense (recovery) included in other comprehensive income 4 (5 ) (4 ) Foreign exchange adjustments (29 ) (25 ) 147 Business combinations (note 7) 1,287 — — Balance – end of year $ 10,975 $ 9,073 $ 9,344 Current income taxes recognized in each operating segment will vary depending upon available income tax deductions related to the nature, timing and amount of capital expenditures incurred in any particular year. During 2017, the British Columbia government enacted legislation that increased the provincial corporate income tax rate from 11% to 12% effective January 1, 2018. As a result of this income tax rate increase, the Company's deferred corporate income tax liability was increased by $10 million . During 2016 , the UK government enacted legislation to reduce the supplementary charge on oil and gas profits from 20% to 10% effective January 1, 2016 , resulting in a decrease in the Company's deferred corporate income tax liability of $107 million . In addition, the UK government also enacted legislation to reduce the PRT rate from 35% to 0% effective January 1, 2016 . Allowable abandonment expenditures eligible for carryback to 2015 and prior taxation years for PRT purposes are still recoverable at a PRT rate of 50% . As a result of these tax changes, the Company’s deferred PRT liability was reduced by $228 million and the deferred corporate income tax liability was increased by $114 million . During 2015 , the Alberta government enacted legislation that increased the provincial corporate income tax rate from 10% to 12% effective July 1, 2015 . As a result of this income tax rate increase, the Company’s deferred corporate income tax liability was increased by $579 million . During 2015 , the UK government enacted legislation that reduced the supplementary charge on oil and gas profits from 32% to 20% effective January 1, 2015 . In addition, the legislation also reduced the PRT rate from 50% to 35% effective January 1, 2016 . Allowable abandonment expenditures eligible for carryback to prior taxation years for PRT purposes were still recoverable at the previous tax rate of 50% . The legislation also replaced the existing Brownfield Allowance with a new Investment Allowance on qualifying capital expenditures, effective April 1, 2015 . The new Investment Allowance is deductible for supplementary charge purposes, subject to certain restrictions. As a result of these tax changes, the Company’s deferred corporate income tax liability was reduced by $217 million and the deferred PRT liability was reduced by $11 million . The Company files income tax returns in the various jurisdictions in which it operates. These tax returns are subject to periodic examinations in the normal course by the applicable tax authorities. The tax returns as prepared may include filing positions that could be subject to differing interpretations of applicable tax laws and regulations, which may take several years to resolve. The Company does not believe the ultimate resolution of these matters will have a material impact upon the Company’s reported results of operations, financial position or liquidity. Deferred income tax assets are recognized for temporary differences to the extent that the realization of the related tax benefit through future taxable profits is probable. The Company has not recognized deferred income tax assets with respect to taxable capital loss carryforwards in excess of $1,000 million in North America, which can be carried forward indefinitely and only applied against future taxable capital gains. In addition, the Company has not recognized deferred income tax assets related to North American tax pools of approximately $650 million , which can only be claimed against income from certain oil and gas properties. Deferred income tax liabilities have not been recognized on the unremitted net earnings of wholly controlled subsidiaries. The Company is able to control the timing and amount of distributions and no taxes are payable on distributions from these subsidiaries provided that the distributions remain within certain limits.

SHARE CAPITAL

SHARE CAPITAL	12 Months Ended
	Dec. 31, 2017
Share Capital, Reserves And Other Equity Interest [Abstract]
SHARE CAPITAL	SHARE CAPITAL Authorized Preferred shares issuable in a series. Unlimited number of common shares without par value. 2017 2016 Issued Common shares Number of shares (thousands) Amount Number of shares Amount Balance – beginning of year 1,110,952 $ 4,671 1,094,668 $ 4,541 Issued for the acquisition of AOSP and other assets (note 7) 97,561 3,818 — — Issued upon exercise of stock options 14,256 466 16,284 559 Previously recognized liability on stock options exercised for common shares — 154 — 117 Return of capital on PrairieSky Royalty Ltd. share distribution (note 8) — — — (546 ) Balance – end of year 1,222,769 $ 9,109 1,110,952 $ 4,671 Preferred Shares Preferred shares are issuable in a series. If issued, the number of shares in each series, and the designation, rights, privileges, restrictions and conditions attached to the shares will be determined by the Board of Directors of the Company. Dividend Policy The Company has paid regular quarterly dividends in each year since 2001 . The dividend policy undergoes periodic review by the Board of Directors and is subject to change. On February 28, 2018, the Board of Directors declared a quarterly dividend of $0.335 per common share, an increase from the previous quarterly dividend of $0.275 per common share. The dividend is payable on April 1, 2018. On March 1, 2017 , the Board of Directors declared a quarterly dividend of $0.275 per common share, beginning with the dividend payable on April 1, 2017 . On November 2, 2016 , the Board of Directors declared a quarterly dividend of $0.25 per common share, beginning with the dividend payable on January 1, 2017 . On March 2, 2016 , the Board of Directors declared a quarterly dividend of $0.23 per common share, beginning with the dividend payable on April 1, 2016 . On March 4, 2015 , the Board of Directors declared a quarterly dividend of $0.23 per common share, beginning with the dividend payable on April 1, 2015 . Normal Course Issuer Bid On May 16, 2017, the Company's application was approved for a Normal Course Issuer Bid to purchase through the facilities of the Toronto Stock Exchange, alternative Canadian trading platforms, and the New York Stock Exchange, up to 27,931,135 common shares, over a 12 month period commencing May 23, 2017 and ending May 22, 2018. During 2017 , 2016 and 2015 , the Company did not purchase any common shares for cancellation. Stock Options The Company’s Option Plan provides for the granting of stock options to employees. Stock options granted under the Option Plan have terms ranging from five to six years to expiry and vest over a five -year period. The exercise price of each stock option granted is determined at the closing market price of the common shares on the Toronto Stock Exchange on the day prior to the grant. Each stock option granted provides the holder the choice to purchase one common share of the Company at the stated exercise price or receive a cash payment equal to the difference between the stated exercise price and the market price of the Company’s common shares on the date of surrender of the stock option. The Option Plan is a "rolling 9% " plan, whereby the aggregate number of common shares that may be reserved for issuance under the plan shall not exceed 9% of the common shares outstanding from time to time. The following table summarizes information relating to stock options outstanding at December 31, 2017 and 2016 : 2017 2016 Stock options (thousands) Weighted average exercise price Stock options (thousands) Weighted Outstanding – beginning of year 58,299 $ 34.22 74,615 $ 34.88 Granted 16,052 $ 42.07 11,002 $ 34.97 Surrendered for cash settlement (626 ) $ 33.18 (817 ) $ 34.47 Exercised for common shares (14,256 ) $ 32.66 (16,284 ) $ 34.31 Forfeited (3,433 ) $ 37.53 (10,217 ) $ 39.66 Outstanding – end of year 56,036 $ 36.67 58,299 $ 34.22 Exercisable – end of year 18,282 $ 34.25 20,747 $ 33.75 The range of exercise prices of stock options outstanding and exercisable at December 31, 2017 was as follows: Stock options outstanding Stock options exercisable Range of exercise prices Stock options outstanding (thousands) Weighted average remaining term (years) Weighted average exercise price Stock options exercisable (thousands) Weighted average exercise price $22.90 - $24.99 3,657 3.03 $ 22.90 1,116 $ 22.90 $25.00 - $29.99 8,390 2.34 $ 28.72 3,967 $ 28.57 $30.00 - $34.99 10,047 1.61 $ 33.31 5,557 $ 33.49 $35.00 - $39.99 13,523 3.29 $ 37.21 4,190 $ 35.88 $40.00 - $44.99 19,417 4.15 $ 43.60 3,118 $ 43.55 $45.00 - $46.74 1,002 3.63 $ 45.61 334 $ 45.09 56,036 3.13 $ 36.67 18,282 $ 34.25

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	12 Months Ended
	Dec. 31, 2017
Analysis Of Other Comprehensive Income By Item [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The components of accumulated other comprehensive income (loss), net of taxes, were as follows: 2017 2016 Derivative financial instruments designated as cash flow hedges $ 47 $ 27 Foreign currency translation adjustment (115 ) 43 $ (68 ) $ 70

CAPITAL DISCLOSURES

CAPITAL DISCLOSURES	12 Months Ended
	Dec. 31, 2017
Corporate Information And Statement Of IFRS Compliance [Abstract]
CAPITAL DISCLOSURES	CAPITAL DISCLOSURES The Company does not have any externally imposed regulatory capital requirements for managing capital. The Company has defined its capital to mean its long-term debt and consolidated shareholders’ equity, as determined at each reporting date. The Company’s objectives when managing its capital structure are to maintain financial flexibility and balance to enable the Company to access capital markets to sustain its on-going operations and to support its growth strategies. The Company primarily monitors capital on the basis of an internally derived financial measure referred to as its "debt to book capitalization ratio", which is the arithmetic ratio of net current and long-term debt divided by the sum of the carrying value of shareholders’ equity plus net current and long-term debt. The Company’s internal targeted range for its debt to book capitalization ratio is 25% to 45% . This range may be exceeded in periods when a combination of capital projects, acquisitions, or lower commodity prices occurs. The Company may be below the low end of the targeted range when cash flow from operating activities is greater than current investment activities. At December 31, 2017 , the ratio was within the target range at 41% . Readers are cautioned that the debt to book capitalization ratio is not defined by IFRS and this financial measure may not be comparable to similar measures presented by other companies. Further, there are no assurances that the Company will continue to use this measure to monitor capital or will not alter the method of calculation of this measure in the future. 2017 2016 Long-term debt, net (1) $ 22,321 $ 16,788 Total shareholders’ equity $ 31,653 $ 26,267 Debt to book capitalization 41% 39% (1) Includes the current portion of long-term debt, net of cash and cash equivalents.

NET EARNINGS (LOSS) PER COMMON

NET EARNINGS (LOSS) PER COMMON SHARE	12 Months Ended
	Dec. 31, 2017
Earnings per share [abstract]
NET EARNINGS (LOSS) PER COMMON SHARE	NET EARNINGS (LOSS) PER COMMON SHARE 2017 2016 2015 Weighted average common shares outstanding – basic (thousands of shares) 1,175,094 1,100,471 1,093,862 Effect of dilutive stock options (thousands of shares) 7,729 — — Weighted average common shares outstanding – diluted (thousands of shares) 1,182,823 1,100,471 1,093,862 Net earnings (loss) $ 2,397 $ (204 ) $ (637 ) Net earnings (loss) per common share – basic $ 2.04 $ (0.19 ) $ (0.58 ) – diluted $ 2.03 $ (0.19 ) $ (0.58 ) In 2017, the Company excluded 17,547,000 potentially anti-dilutive stock options from the calculation of diluted earnings per common share.

INTEREST AND OTHER FINANCING EX

INTEREST AND OTHER FINANCING EXPENSE	12 Months Ended
	Dec. 31, 2017
Borrowing costs [abstract]
INTEREST AND OTHER FINANCING EXPENSE	INTEREST AND OTHER FINANCING EXPENSE 2017 2016 2015 Interest and other financing expense: Long-term debt $ 810 $ 664 $ 618 Other (1) — — 1 810 664 619 Less: amounts capitalized on qualifying assets 82 233 244 Total interest and other financing expense 728 431 375 Total interest income (97 ) (48 ) (53 ) Net interest and other financing expense $ 631 $ 383 $ 322 (1) Includes the fair value impact of interest rate swaps on US dollar debt securities.

FINANCIAL INSTRUMENTS

FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2017
Financial Instruments [Abstract]
FINANCIAL INSTRUMENTS	FINANCIAL INSTRUMENTS The carrying amounts of the Company’s financial instruments by category were as follows: 2017 Asset (liability) Financial assets at amortized cost Fair value through profit or loss Derivatives used for hedging Financial liabilities at amortized cost Total Accounts receivable $ 2,397 $ — $ — $ — $ 2,397 Investments — 893 — — 893 Other long-term assets 510 — 204 — 714 Accounts payable — — — (775 ) (775 ) Accrued liabilities — — — (2,597 ) (2,597 ) Other long-term liabilities (1) — (38 ) (65 ) (469 ) (572 ) Long-term debt (2) — — — (22,458 ) (22,458 ) $ 2,907 $ 855 $ 139 $ (26,299 ) $ (22,398 ) 2016 Asset (liability) Financial assets at amortized cost Fair value through profit or loss Derivatives used for hedging Financial liabilities at amortized cost Total Accounts receivable $ 1,434 $ — $ — $ — $ 1,434 Investments — 913 — — 913 Other long-term assets 385 4 485 — 874 Accounts payable — — — (595 ) (595 ) Accrued liabilities — — — (2,222 ) (2,222 ) Long-term debt (2) — — — (16,805 ) (16,805 ) $ 1,819 $ 917 $ 485 $ (19,622 ) $ (16,401 ) (1) Includes $469 million ( US$375 million ) of deferred purchase consideration payable to Marathon in March 2018. (2) Includes the current portion of long-term debt. The carrying amounts of the Company’s financial instruments approximated their fair value, except for fixed rate long-term debt. The fair values of the Company’s investments, recurring other long-term assets (liabilities) and fixed rate long-term debt are outlined below: 2017 Carrying amount Fair value Asset (liability) (1) (2) Level 1 Level 2 Level 3 Investments (3) $ 893 $ 893 $ — $ — Other long-term assets (4) $ 714 $ — $ 204 $ 510 Other long-term liabilities $ (103 ) $ — $ (103 ) $ — Fixed rate long-term debt (5) (6) $ (15,989 ) $ (17,259 ) $ — $ — 2016 Carrying amount Fair value Asset (liability) (1) (2) Level 1 Level 2 Level 3 Investments (3) $ 913 $ 913 $ — $ — Other long-term assets (4) $ 874 $ — $ 489 $ 385 Fixed rate long-term debt (5) (6) $ (12,498 ) $ (13,217 ) $ — $ — (1) Excludes financial assets and liabilities where the carrying amount approximates fair value due to the liquid nature of the asset or liability (cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities, and deferred purchase consideration payable to Marathon in March 2018). (2) There were no transfers between Level 1, 2 and 3 financial instruments. (3) The fair value of the investments are based on quoted market prices. (4) The fair value of Redwater Partnership subordinated debt is based on the present value of future cash receipts. (5) The fair value of fixed rate long-term debt has been determined based on quoted market prices. (6) Includes the current portion of fixed rate long-term debt. The following provides a summary of the carrying amounts of derivative financial instruments held and a reconciliation to the Company’s consolidated balance sheets. Asset (liability) 2017 2016 Derivatives held for trading Foreign currency forward contracts $ (38 ) $ 10 Natural gas AECO swaps — (6 ) Cash flow hedges Foreign currency forward contracts (71 ) 16 Cross currency swaps 210 469 $ 101 $ 489 Included within: Current portion of other long-term (liabilities) assets $ (103 ) $ 222 Other long-term assets 204 267 $ 101 $ 489 During 2017 , the Company recognized a gain of $5 million ( 2016 – gain of $7 million , 2015 – gain of $5 million ) related to ineffectiveness arising from cash flow hedges. The estimated fair value of derivative financial instruments in Level 2 at each measurement date have been determined based on appropriate internal valuation methodologies and/or third party indications. Level 2 fair values determined using valuation models require the use of assumptions concerning the amount and timing of future cash flows and discount rates. In determining these assumptions, the Company primarily relied on external, readily-observable quoted market inputs as applicable, including crude oil and natural gas forward benchmark commodity prices and volatility, Canadian and United States forward interest rate yield curves, and Canadian and United States foreign exchange rates, discounted to present value as appropriate . The resulting fair value estimates may not necessarily be indicative of the amounts that could be realized or settled in a current market transaction and these differences may be material. Risk Management The Company periodically uses derivative financial instruments to manage its commodity price, interest rate and foreign currency exposures. These financial instruments are entered into solely for hedging purposes and are not used for speculative purposes. The changes in estimated fair values of derivative financial instruments included in the risk management asset were recognized in the financial statements as follows: Asset (liability) 2017 2016 Balance – beginning of year $ 489 $ 854 Net change in fair value of outstanding derivative financial instruments recognized in: Risk management activities (37 ) (25 ) Foreign exchange (375 ) (304 ) Other comprehensive income (loss) 24 (36 ) Balance – end of year 101 489 Less: current portion (103 ) 222 $ 204 $ 267 Net loss (gain) from risk management activities for the years ended December 31 were as follows: 2017 2016 2015 Net realized risk management (gain) loss $ (2 ) $ 8 $ (843 ) Net unrealized risk management loss 37 25 374 $ 35 $ 33 $ (469 ) Financial Risk Factors a) Market risk Market risk is the risk that the fair value or future cash flows of a financial instrument will fluctuate because of changes in market prices. The Company’s market risk is comprised of commodity price risk, interest rate risk, and foreign currency exchange risk. Commodity price risk management The Company periodically uses commodity derivative financial instruments to manage its exposure to commodity price risk associated with the sale of its future crude oil and natural gas production and with natural gas purchases. At December 31, 2017 , the Company had no derivative financial instruments outstanding. Interest rate risk management The Company is exposed to interest rate price risk on its fixed rate long-term debt and to interest rate cash flow risk on its floating rate long-term debt. The Company periodically enters into interest rate swap contracts to manage its fixed to floating interest rate mix on long-term debt. Interest rate swap contracts require the periodic exchange of payments without the exchange of the notional principal amounts on which the payments are based. At December 31, 2017 , the Company had no interest rate swap contracts outstanding. Foreign currency exchange rate risk management The Company is exposed to foreign currency exchange rate risk in Canada primarily related to its US dollar denominated long-term debt and working capital. The Company is also exposed to foreign currency exchange rate risk on transactions conducted in other currencies and in the carrying value of its foreign subsidiaries. The Company periodically enters into cross currency swap contracts and foreign currency forward contracts to manage known currency exposure on US dollar denominated long-term debt and working capital. The cross currency swap contracts require the periodic exchange of payments with the exchange at maturity of notional principal amounts on which the payments are based. At December 31, 2017 the Company had the following cross currency swap contracts outstanding: Remaining term Amount Exchange rate (US$/C$) Interest rate (US$) Interest rate (C$) Cross currency Swaps Jan 2018 — Nov 2021 US$500 1.022 3.45 % 3.96 % Jan 2018 — Mar 2038 US$550 1.170 6.25 % 5.76 % All cross currency swap derivative financial instruments were designated as hedges at December 31, 2017 and were classified as cash flow hedges. In addition to the cross currency swap contracts noted above, at December 31, 2017 the Company had US$3,705 million of foreign currency forward contracts outstanding, with terms of up to 90 days, including US$2,339 million designated as cash flow hedges. Financial instrument sensitivities The following table summarizes the annualized sensitivities of the Company’s 2017 net earnings and other comprehensive income (loss) to changes in the fair value of financial instruments outstanding as at December 31, 2017 , resulting from changes in the specified variable, with all other variables held constant. These sensitivities are prepared on a different basis than those sensitivities disclosed in the Company’s other continuous disclosure documents, are limited to the impact of changes in a specified variable applied to financial instruments only and do not represent the impact of a change in the variable on the operating results of the Company taken as a whole. Further, these sensitivities are theoretical, as changes in one variable may contribute to changes in another variable, which may magnify or counteract the sensitivities. In addition, changes in fair value generally cannot be extrapolated because the relationship of a change in an assumption to the change in fair value may not be linear. Increase (decrease) to net earnings (Increase) decrease to other comprehensive loss Interest rate risk Increase interest rate 1% $ (42 ) $ (16 ) Decrease interest rate 1% $ 42 $ 19 Foreign currency exchange rate risk Increase exchange rate by US$0.01 $ (105 ) $ — Decrease exchange rate by US$0.01 $ 101 $ — b) Credit Risk Credit risk is the risk that a party to a financial instrument will cause a financial loss to the Company by failing to discharge an obligation. Counterparty credit risk management The Company’s accounts receivable are mainly with customers in the crude oil and natural gas industry and are subject to normal industry credit risks. The Company manages these risks by reviewing its exposure to individual companies on a regular basis and where appropriate, ensures that parental guarantees or letters of credit are in place to minimize the impact in the event of default. At December 31, 2017 , substantially all of the Company’s accounts receivable were due within normal trade terms. The Company is also exposed to possible losses in the event of nonperformance by counterparties to derivative financial instruments; however, the Company manages this credit risk by entering into agreements with counterparties that are substantially all investment grade financial institutions. At December 31, 2017 , the Company had net risk management assets of $187 million with specific counterparties related to derivative financial instruments ( December 31, 2016 – $489 million ). The carrying amount of financial assets approximates the maximum credit exposure. c) Liquidity risk Liquidity risk is the risk that the Company will encounter difficulty in meeting obligations associated with financial liabilities. Management of liquidity risk requires the Company to maintain sufficient cash and cash equivalents, along with other sources of capital, consisting primarily of cash flow from operating activities, available credit facilities, commercial paper and access to debt capital markets, to meet obligations as they become due. The Company believes it has adequate bank credit facilities to provide liquidity to manage fluctuations in the timing of the receipt and/or disbursement of operating cash flows. The maturity dates for financial liabilities were as follows: Less than 1 year 1 to less than 2 years 2 to less than 5 years Thereafter Accounts payable $ 775 $ — $ — $ — Accrued liabilities $ 2,597 $ — $ — $ — Other long-term liabilities (1) $ 572 $ — $ — $ — Long-term debt (2) (3) $ 2,027 $ 4,228 $ 5,991 $ 10,351 (1) Includes $469 million ( US$375 million ) of deferred purchase consideration payable to Marathon in March 2018. (2) Long-term debt represents principal repayments only and does not reflect interest, original issue discounts and premiums or transaction costs. (3) In addition to the financial liabilities disclosed above, estimated interest and other financing payments related to long-term debt are as follows: less than one year, $842 million ; one to less than two years, $755 million ; two to less than five years, $1,712 million ; and thereafter, $5,384 million . Interest payments were estimated based upon applicable interest and foreign exchange rates as at December 31, 2017 .

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2017
Other Provisions, Contingent Liabilities And Contingent Assets [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES The Company has committed to certain payments as follows: 2018 2019 2020 2021 2022 Thereafter Product transportation and pipeline $ 680 $ 584 $ 526 $ 482 $ 422 $ 3,868 Offshore equipment operating leases $ 181 $ 92 $ 70 $ 68 $ 8 $ — Office leases $ 43 $ 42 $ 42 $ 39 $ 30 $ 118 Other (1) $ 87 $ 41 $ 40 $ 39 $ 43 $ 333 (1) In addition to the amounts disclosed above, beginning on the earlier of the commercial operations date of the Redwater refinery and June 1, 2018, the Company is unconditionally obligated to pay its 25% pro rata share of the debt portion of the monthly cost of service toll, including interest, fees and principal repayments, of the syndicated credit facility and bonds, over the tolling period of 30 years . See Note 9. In addition to the commitments disclosed above, the Company has entered into various agreements related to the engineering, procurement and construction of its various development projects. These contracts can be cancelled by the Company upon notice without penalty, subject to the costs incurred up to and in respect of the cancellation. The Company is defendant and plaintiff in a number of legal actions arising in the normal course of business. In addition, the Company is subject to certain contractor construction claims. The Company believes that any liabilities that might arise pertaining to any such matters would not have a material effect on its consolidated financial position.

SUPPLEMENTAL DISCLOSURE OF CASH

SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION	12 Months Ended
	Dec. 31, 2017
Statement Of Cash Flows, Additional Disclosures [Abstract]
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION	SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION 2017 2016 2015 Changes in non-cash working capital Accounts receivable $ (977 ) $ (142 ) $ 615 Current income tax assets 527 (165 ) (447 ) Inventory 81 (79 ) 142 Prepaids and other (28 ) 14 11 Accounts payable 175 31 7 Accrued liabilities 365 (116 ) (981 ) Other long-term liabilities (1) 469 — — Net changes in non-cash working capital $ 612 $ (457 ) $ (653 ) Relating to: Operating activities $ 299 $ (542 ) $ 239 Financing activities — — (40 ) Investing activities 313 85 (852 ) $ 612 $ (457 ) $ (653 ) 2017 2016 2015 Expenditures on exploration and evaluation assets $ 159 $ 29 $ 180 Net proceeds on sale of exploration and evaluation assets (2) (35 ) (35 ) (416 ) Net expenditures (proceeds) on exploration and evaluation assets $ 124 $ (6 ) $ (236 ) Expenditures on property, plant and equipment $ 4,574 $ 4,152 $ 5,118 Net proceeds on sale of property, plant and equipment (2) (3) — (349 ) (414 ) Net expenditures on property, plant and equipment $ 4,574 $ 3,803 $ 4,704 (1) Included in other long-term liabilities at December 31, 2017 is $469 million ( US$375 million ) of deferred purchase consideration payable to Marathon in March 2018. (2) Net proceeds on exploration and evaluation assets and net expenditures on property, plant and equipment in 2015 exclude non-cash share consideration of $985 million received from PrairieSky on the disposition of royalty income assets. (3) Net expenditures on property, plant and equipment in 2016 exclude non-cash share consideration of $190 million received from Inter Pipeline on the disposition of the Company's interest in the Cold Lake Pipeline. The following table summarizes movements in the Company's liabilities arising from financing activities for the year ended December 31, 2017: Long-term debt Cash flow hedges on US dollar debt securities Liabilities from financing activities At December 31, 2016 $ 16,805 $ (485 ) $ 16,320 Changes from financing cash flows: Issue of long-term debt, net (1) 6,622 — 6,622 Settlement of hedge instruments, net — 124 124 Changes in foreign exchange and fair value (2) (969 ) 222 (747 ) At December 31, 2017 $ 22,458 $ (139 ) $ 22,319 (1) Includes original issue discounts and premiums, and directly attributable transaction costs. (2) Includes foreign exchange (gain) loss, changes in the fair value of cash flow hedges on US dollar debt and the amortization of original issue discounts and premiums and directly attributable transaction costs.

SEGMENTED INFORMATION

SEGMENTED INFORMATION	12 Months Ended
	Dec. 31, 2017
Operating Segments [Abstract]
SEGMENTED INFORMATION	SEGMENTED INFORMATION The Company’s exploration and production activities are conducted in three geographic segments: North America, North Sea and Offshore Africa. These activities include the exploration, development, production and marketing of crude oil, natural gas liquids and natural gas. The Company’s Oil Sands Mining and Upgrading activities are reported in a separate segment from exploration and production activities. North America North Sea Offshore Africa (millions of Canadian dollars) 2017 2016 2015 2017 2016 2015 2017 2016 2015 Segmented product sales $ 9,161 $ 7,209 $ 9,222 $ 784 $ 570 $ 638 $ 632 $ 603 $ 482 Less: royalties (809 ) (524 ) (732 ) (1 ) (1 ) (1 ) (41 ) (26 ) (22 ) Segmented revenue 8,352 6,685 8,490 783 569 637 591 577 460 Segmented expenses Production 2,362 2,186 2,603 400 403 544 226 200 223 Transportation, blending and feedstock 2,291 1,941 2,309 31 48 61 1 2 2 Depletion, depreciation and amortization 3,243 3,465 4,248 509 458 388 205 262 273 Asset retirement obligation accretion 80 66 93 27 35 39 9 12 10 Realized risk management activities (2 ) 8 (843 ) — — — — — — Gain on acquisition, disposition and revaluation of properties (35 ) (32 ) (739 ) — — — — — — (Gain) loss from investments (7 ) (320 ) 6 — — — — — — Total segmented expenses 7,932 7,314 7,677 967 944 1,032 441 476 508 Segmented earnings (loss) before the following $ 420 $ (629 ) $ 813 $ (184 ) $ (375 ) $ (395 ) $ 150 $ 101 $ (48 ) Non–segmented expenses Administration Share-based compensation Interest and other financing expense Unrealized risk management activities Foreign exchange (gain) loss Total non–segmented expenses Earnings (loss) before taxes Current income tax recovery Deferred income tax expense (recovery) Net earnings (loss) Midstream activities include the Company’s pipeline operations, an electricity co-generation system and Redwater Partnership. Production activities that are not included in the above segments are reported in the segmented information as other. Inter-segment eliminations include internal transportation and electricity charges. Segmented revenue and segmented results include transactions between business segments. Sales between segments are made at prices that approximate market prices, taking into account the volumes involved. These transactions and any unrealized profits and losses are eliminated on consolidation, unless unrealized losses provide evidence of an impairment of the asset transferred. Sales to external customers are based on the location of the seller. Operating segments are reported in a manner consistent with the internal reporting provided to the Company’s chief operating decision makers. Oil Sands Mining and Upgrading Midstream Inter–segment elimination and other Total 2017 2016 2015 2017 2016 2015 2017 2016 2015 2017 2016 2015 $ 7,072 $ 2,657 $ 2,764 $ 102 $ 114 $ 136 $ (82 ) $ (55 ) $ (75 ) $ 17,669 $ 11,098 $ 13,167 (167 ) (24 ) (49 ) — — — — — — (1,018 ) (575 ) (804 ) 6,905 2,633 2,715 102 114 136 (82 ) (55 ) (75 ) 16,651 10,523 12,363 2,600 1,292 1,332 16 25 32 (8 ) (7 ) (8 ) 5,596 4,099 4,726 679 80 82 — — — (85 ) (68 ) (75 ) 2,917 2,003 2,379 1,220 662 562 9 11 12 — — — 5,186 4,858 5,483 48 29 31 — — — — — — 164 142 173 — — — — — — — — — (2 ) 8 (843 ) (230 ) — — (114 ) (218 ) — — — — (379 ) (250 ) (739 ) — — — (31 ) (7 ) 44 — — — (38 ) (327 ) 50 4,317 2,063 2,007 (120 ) (189 ) 88 (93 ) (75 ) (83 ) 13,444 10,533 11,229 $ 2,588 $ 570 $ 708 $ 222 $ 303 $ 48 $ 11 $ 20 $ 8 3,207 (10 ) 1,134 319 345 390 134 355 (46 ) 631 383 322 37 25 374 (787 ) (55 ) 761 334 1,053 1,801 2,873 (1,063 ) (667 ) (164 ) (618 ) (261 ) 640 (241 ) 231 $ 2,397 $ (204 ) $ (637 ) Capital Expenditures (1) 2017 2016 Net (2) expenditures Non-cash and fair value changes (2) (3) Capitalized costs Net expenditures (proceeds) Non-cash and fair value changes (3) Capitalized costs Exploration and evaluation assets Exploration and Production North America (4) $ 160 $ (184 ) $ (24 ) $ 17 $ (211 ) $ (194 ) North Sea — — — — — — Offshore Africa 15 — 15 9 (18 ) (9 ) Oil Sands Mining and Upgrading 142 117 259 — — — $ 317 $ (67 ) $ 250 $ 26 $ (229 ) $ (203 ) Property, plant and equipment Exploration and Production North America $ 2,815 $ 354 $ 3,169 $ 1,143 $ (36 ) $ 1,107 North Sea 160 95 255 126 60 186 Offshore Africa 89 12 101 142 (26 ) 116 3,064 461 3,525 1,411 (2 ) 1,409 Oil Sands Mining and Upgrading (5) 9,592 5,454 15,046 2,718 (23 ) 2,695 Midstream (6) (7) 80 114 194 (315 ) (28 ) (343 ) Head office 19 — 19 17 — 17 $ 12,755 $ 6,029 $ 18,784 $ 3,831 $ (53 ) $ 3,778 (1) This table provides a reconciliation of capitalized costs including derecognitions and does not include the impact of foreign exchange adjustments. (2) Net expenditures on exploration and evaluation assets and property, plant and equipment for the year ended December 31, 2017 exclude non-cash share consideration of $3,818 million issued on the acquisition of AOSP and other assets. This non-cash consideration is included in non-cash and other fair value changes. (3) Asset retirement obligations, transfers of exploration and evaluation assets, transfers of property, plant and equipment to inventory due to change in use, and other fair value adjustments. (4) The above noted figures for 2017 do not include the impact of a pre-tax cash gain of $35 million (2016 - $32 million pre-tax cash gain) on the disposition of exploration and evaluation assets. (5) Net expenditures for Oil Sands Mining and Upgrading include capitalized interest and share-based compensation. (6) The above noted figures for 2016 do not include a pre-tax cash and non-cash gain of $218 million on the disposition of certain Midstream assets to Inter Pipeline. (7) The above noted figures for 2017 include the impact of a pre-tax non-cash revaluation gain of $114 million ( $83 million after-tax) related to a previously held joint interest in a pipeline system. Segmented Assets 2017 2016 Exploration and Production North America $ 28,705 $ 28,892 North Sea 1,854 2,269 Offshore Africa 1,331 1,580 Other 29 29 Oil Sands Mining and Upgrading 40,559 24,852 Midstream 1,279 912 Head office 110 114 $ 73,867 $ 58,648

REMUNERATION OF DIRECTORS AND S

REMUNERATION OF DIRECTORS AND SENIOR MANAGEMENT	12 Months Ended
	Dec. 31, 2017
Related Party [Abstract]
REMUNERATION OF DIRECTORS AND SENIOR MANAGEMENT	REMUNERATION OF DIRECTORS AND SENIOR MANAGEMENT Remuneration of Non-Management Directors 2017 2016 2015 Fees earned $ 3 $ 2 $ 2 Remuneration of Senior Management (1) 2017 2016 2015 Salary $ 3 $ 3 $ 3 Common stock option based awards 10 9 7 Annual incentive plans 5 5 2 Long-term incentive plans 17 15 6 $ 35 $ 32 $ 18 (1) Senior management identified above are consistent with the disclosure on Named Executive Officers provided in the Company’s Information Circular to shareholders for the respective years.

ACCOUNTING POLICIES (Policies)

ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2017
Corporate Information And Statement Of IFRS Compliance [Abstract]
IFRS compliance	The Company’s consolidated financial statements and the related notes have been prepared in accordance with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”). The accounting policies adopted by the Company under IFRS are set out below. The Company has consistently applied the same accounting policies throughout all periods presented, except where IFRS permits new accounting standards to be adopted prospectively.
Principles of consolidation	PRINCIPLES OF CONSOLIDATION The consolidated financial statements have been prepared under the historical cost basis, unless otherwise required. The consolidated financial statements include the accounts of the Company and all of its subsidiary companies and wholly owned partnerships. Subsidiaries are all entities over which the Company has control. Subsidiaries are consolidated from the date on which the Company obtains control. They are deconsolidated from the date that control ceases. Certain of the Company’s activities are conducted through joint arrangements in which two or more parties have joint control. Where the Company has determined that it has a direct ownership interest in jointly controlled assets and obligations for the liabilities (a “joint operation”), the assets, liabilities, revenue and expenses related to the joint operation are included in the consolidated financial statements in proportion to the Company’s interest. Where the Company has determined that it has an interest in jointly controlled entities (a “joint venture”), it uses the equity method of accounting. Under the equity method, the Company’s initial and subsequent investments are recognized at cost and subsequently adjusted for the Company’s share of the joint venture’s income or loss, less distributions received. Joint ventures accounted for using the equity method of accounting are tested for impairment whenever objective evidence indicates that the carrying amount of the investment may not be recoverable. Indications of impairment include a history of losses, significant capital expenditure overruns, liquidity concerns, financial restructuring of the investee or significant adverse changes in the technological, economic or legal environment. The amount of the impairment is measured as the difference between the carrying amount of the investment and the higher of its fair value less costs of disposal and its value in use. Impairment losses are reversed in subsequent periods if the amount of the loss decreases and the decrease can be related objectively to an event occurring after the impairment was recognized.
Segmented information	SEGMENTED INFORMATION Operating segments have been determined based on the nature of the Company’s activities and the geographic locations in which the Company operates, and are consistent with the level of information regularly provided to and reviewed by the Company’s chief operating decision makers.
Cash and cash equivalents	CASH AND CASH EQUIVALENTS Cash comprises cash on hand and demand deposits. Other investments (term deposits and certificates of deposit) with an original term to maturity at purchase of three months or less are reported as cash equivalents in the consolidated balance sheets.
Inventory	INVENTORY Inventory is primarily comprised of product inventory and materials and supplies. Product inventory is comprised of crude oil held for sale, including pipeline linefill and crude oil stored in floating production, storage and offloading vessels. Inventories are carried at the lower of cost and net realizable value. Cost consists of purchase costs, direct production costs, directly attributable overhead and depletion, depreciation and amortization and is determined on a first-in, first-out basis. Net realizable value for product inventory is determined by reference to forward prices, and for materials and supplies is based on current market prices as at the date of the consolidated balance sheets.
Exploration and evaluation assets	EXPLORATION AND EVALUATION ASSETS Exploration and evaluation (“E&E”) assets consist of the Company’s crude oil and natural gas exploration projects that are pending the determination of proved reserves. E&E costs are initially capitalized and include costs directly associated with the acquisition of licenses, technical services and studies, seismic acquisition, exploration drilling and evaluation, overhead and administration expenses, and the estimate of any asset retirement costs. E&E costs do not include general prospecting or evaluation costs incurred prior to having obtained the legal rights to explore an area. These costs are recognized in net earnings. Once the technical feasibility and commercial viability of E&E assets are determined and a development decision is made by management, the E&E assets are tested for impairment upon reclassification to property, plant and equipment. The technical feasibility and commercial viability of extracting a mineral resource is considered to be determined when an assessment of proved reserves is made. An E&E asset is derecognized upon disposal or when no future economic benefits are expected to arise from its use. Any gain or loss arising on derecognition of the asset is recognized in net earnings within depletion, depreciation and amortization. E&E assets are also tested for impairment when facts and circumstances suggest that the carrying amount of E&E assets may exceed their recoverable amount, by comparing the relevant costs to the fair value of the related Cash Generating Units (“CGUs”), aggregated at a segment level. Indications of impairment include leases approaching expiry, the existence of low benchmark commodity prices for an extended period of time, significant downward revisions in estimated probable reserves volumes, significant increases in estimated future exploration or development expenditures, or significant adverse changes in the applicable legislative or regulatory frameworks.
Property, plant and equipment	PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment is measured at cost less accumulated depletion and depreciation and impairment provisions. Assets under construction are not depleted or depreciated until available for their intended use. The capitalized value of a finance lease is included in property, plant and equipment. Exploration and Production The cost of an asset comprises its acquisition costs, construction and development costs, costs directly attributable to bringing the asset into operation, the estimate of any asset retirement costs, and applicable borrowing costs. Property acquisition costs are comprised of the aggregate amount paid and the fair value of any other consideration given to acquire the asset. When significant components of an item of property, plant and equipment, including crude oil and natural gas interests, have different useful lives, they are accounted for separately. Crude oil and natural gas properties are depleted using the unit-of-production method over proved reserves, except for major components, which are depreciated using a straight-line method over their estimated useful lives. The unit-of-production depletion rate takes into account expenditures incurred to date, together with future development expenditures required to develop proved reserves. Oil Sands Mining and Upgrading Capitalized costs for the Oil Sands Mining and Upgrading segment are reported separately from the Company’s North America Exploration and Production segment. Capitalized costs include acquisition costs, construction and development costs, costs directly attributable to bringing the asset into operation, the estimate of any asset retirement costs, and applicable borrowing costs. Mine-related costs are depleted using the unit-of-production method based on proved reserves. Costs of the upgraders and related infrastructure located on the Horizon and AOSP sites are depreciated on the unit-of-production method based on the estimated productive capacity of the respective upgraders and related infrastructure. Other equipment is depreciated on a straight-line basis over its estimated useful life ranging from 2 to 18 years. Midstream and Head Office The Company capitalizes all costs that expand the capacity or extend the useful life of the midstream and head office assets. Midstream assets are depreciated on a straight-line basis over their estimated useful lives ranging from 5 to 30 years. Head office assets are depreciated on a declining balance basis. Useful lives The depletion rates and expected useful lives of property, plant and equipment are reviewed on an annual basis, with changes in depletion rates and useful lives accounted for prospectively. Derecognition A property, plant and equipment asset is derecognized upon disposal or when no future economic benefits are expected to arise from the continued use of the asset. Any gain or loss arising on derecognition of the asset (calculated as the difference between the net disposal proceeds and the carrying amount of the asset) is recognized in net earnings within depletion, depreciation and amortization. Major maintenance expenditures Inspection costs associated with major maintenance turnarounds are capitalized and depreciated over the period to the next major maintenance turnaround. All other maintenance costs are expensed as incurred. Impairment The Company assesses property, plant and equipment for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset or group of assets may not be recoverable. Indications of impairment include the existence of low benchmark commodity prices for an extended period of time, significant downward revisions of estimated reserves volumes, significant increases in estimated future development expenditures, or significant adverse changes in the applicable legislative or regulatory frameworks. If an indication of impairment exists, the Company performs an impairment test related to the assets. Individual assets are grouped for impairment assessment purposes into CGUs, which are the lowest level at which there are identifiable cash inflows that are largely independent of the cash inflows of other groups of assets. A CGUs recoverable amount is the higher of its fair value less costs of disposal and its value in use. Where the carrying amount of a CGU exceeds its recoverable amount, the CGU is considered impaired and is written down to its recoverable amount through depletion, depreciation and amortization expense. In subsequent periods, an assessment is made at each reporting date to determine whether there is any indication that previously recognized impairment losses may no longer exist or may have decreased. If such indication exists, the recoverable amount is re-estimated and the net carrying amount of the asset is increased to its revised recoverable amount. The revised recoverable amount cannot exceed the carrying amount that would have been determined, net of depletion, depreciation and amortization, had no impairment loss been recognized for the asset in prior periods. A reversal of impairment is recognized in net earnings. After a reversal, the depletion, depreciation and amortization charge is adjusted in future periods to allocate the asset’s revised carrying amount over its remaining useful life.
Business combinations	BUSINESS COMBINATIONS Business combinations are accounted for using the acquisition method. Assets acquired and liabilities assumed in a business combination are recognized at their fair value at the date of the acquisition. Any excess of the consideration paid over the fair value of the net assets acquired is recognized as an asset. Any excess of the fair value of the net assets acquired over the consideration paid is recognized in net earnings.
Overburden removal costs	OVERBURDEN REMOVAL COSTS Overburden removal costs incurred during the initial development of a mine at Horizon and AOSP are capitalized to property, plant and equipment. Overburden removal costs incurred during the production of a mine are included in the cost of inventory, unless the overburden removal activity has resulted in a probable inflow of future economic benefits to the Company, in which case the costs are capitalized to property, plant and equipment. Capitalized overburden removal costs are depleted over the life of the mining reserves that directly benefit from the overburden removal activity.
Capitalized borrowing costs	CAPITALIZED BORROWING COSTS Borrowing costs attributable to the acquisition, construction or production of qualifying assets are capitalized to the cost of those assets until such time as the assets are substantially available for their intended use. Qualifying assets are comprised of those significant assets that require a period greater than one year to be available for their intended use. All other borrowing costs are recognized in net earnings.
Leases	LEASES Finance leases, which transfer substantially all of the risks and rewards incidental to ownership of the leased item to the Company, are capitalized at the commencement of the lease term at the fair value of the leased property or, if lower, at the present value of the minimum lease payments. Capitalized leased assets are depreciated over the shorter of the estimated useful life of the asset or the lease term. Operating lease payments are recognized in net earnings over the lease term.
Asset retirement obligations	ASSET RETIREMENT OBLIGATIONS The Company provides for asset retirement obligations on all of its property, plant and equipment based on current legislation and industry operating practices. Provisions for asset retirement obligations related to property, plant and equipment are recognized as a liability in the period in which they are incurred. Provisions are measured at the present value of management’s best estimate of expenditures required to settle the obligation as at the date of the balance sheets. Subsequent to the initial measurement, the obligation is adjusted to reflect the passage of time, changes in credit adjusted interest rates, and changes in the estimated future cash flows underlying the obligation. The increase in the provision due to the passage of time is recognized as asset retirement obligation accretion expense whereas changes due to discount rates or estimated future cash flows are capitalized to or derecognized from property, plant and equipment. Actual costs incurred upon settlement of the asset retirement obligation are charged against the provision.
Foreign currency translation	FOREIGN CURRENCY TRANSLATION Functional and presentation currency Items included in the financial statements of the Company’s subsidiary companies and partnerships are measured using the currency of the primary economic environment in which the subsidiary operates (the “functional currency”). The consolidated financial statements are presented in Canadian dollars, which is the Company’s functional currency. The assets and liabilities of subsidiaries that have a functional currency different from that of the Company are translated into Canadian dollars at the closing rate at the date of the balance sheets, and revenue and expenses are translated at the average rate for the period. Cumulative foreign currency translation adjustments are recognized in other comprehensive income. When the Company disposes of its entire interest in a foreign operation, or loses control, joint control, or significant influence over a foreign operation, the foreign currency gains or losses accumulated in other comprehensive income related to the foreign operation are recognized in net earnings. Transactions and balances Foreign currency transactions are translated into the functional currency of the Company and its subsidiaries and partnerships using the exchange rates prevailing at the dates of the transactions. Foreign exchange gains and losses resulting from the settlement of foreign currency transactions and from the translation at balance sheet date exchange rates of monetary assets and liabilities denominated in currencies other than the functional currency are recognized in net earnings.
Revenue recognition	REVENUE RECOGNITION AND COSTS OF GOODS SOLD Revenue from the sale of crude oil and natural gas is recognized when title passes to the customer, delivery has taken place and collection is reasonably assured. The Company assesses customer creditworthiness, both before entering into contracts and throughout the revenue recognition process. Revenue represents the Company’s share net of royalty payments to governments and other mineral interest owners.
Costs of goods sold	Related costs of goods sold are comprised of production, transportation, blending and feedstock, and depletion, depreciation and amortization expenses. These amounts have been separately presented in the consolidated statements of earnings.
Production sharing contracts	PRODUCTION SHARING CONTRACTS Production generated from Côte d’Ivoire and Gabon in Offshore Africa is shared under the terms of various Production Sharing Contracts (“PSCs”). Product sales are divided into cost recovery oil and profit oil. Cost recovery oil allows the Company to recover its capital and production costs and the costs carried by the Company on behalf of the respective government state oil companies (the “Governments”). Profit oil is allocated to the joint venture partners in accordance with their respective equity interests, after a portion has been allocated to the Governments. The Governments’ share of profit oil attributable to the Company’s equity interest is allocated to royalty expense and current income tax expense in accordance with the terms of the respective PSCs.
Income tax	INCOME TAX The Company follows the liability method of accounting for income taxes. Under this method, deferred income tax assets and liabilities are recognized based on the estimated income tax effects of temporary differences in the carrying amount of assets and liabilities in the consolidated financial statements and their respective tax bases. Deferred income tax assets and liabilities are calculated using the substantively enacted income tax rates that are expected to apply when the asset or liability is recovered. Deferred income tax assets or liabilities are not recognized when they arise on the initial recognition of an asset or liability in a transaction (other than in a business combination) that, at the time of the transaction, affects neither accounting nor taxable profit. Deferred income tax assets or liabilities are also not recognized on possible future distributions of retained earnings of subsidiaries where the timing of the distribution can be controlled by the Company and it is probable that a distribution will not be made in the foreseeable future, or when distributions can be made without incurring income taxes. Deferred income tax assets for deductible temporary differences and tax loss carryforwards are recognized to the extent that it is probable that future taxable profits will be available against which the temporary differences or tax loss carryforwards can be utilized. The carrying amount of deferred income tax assets is reviewed at each reporting date, and is reduced if it is no longer probable that sufficient future taxable profits will be available against which the temporary differences or tax loss carryforwards can be utilized. Current income tax is calculated based on net earnings for the period, adjusted for items that are non-taxable or taxed in different periods, using income tax rates that are substantively enacted at each reporting date. Income taxes are recognized in net earnings or other comprehensive income, consistent with the items to which they relate.
Share-based compensation	SHARE-BASED COMPENSATION The Company’s Stock Option Plan (the “Option Plan”) provides current employees with the right to elect to receive common shares or a cash payment in exchange for stock options surrendered. The liability for awards granted to employees is initially measured based on the grant date fair value of the awards and the number of awards expected to vest. The awards are re-measured each reporting period for subsequent changes in the fair value of the liability. Fair value is determined using the Black-Scholes valuation model under a graded vesting method. Expected volatility is estimated based on historic results. When stock options are surrendered for cash, the cash settlement paid reduces the outstanding liability. When stock options are exercised for common shares under the Option Plan, consideration paid by the employee and any previously recognized liability associated with the stock options are recorded as share capital. The Company grants Performance Share Units ("PSUs") to certain executive employees. The PSUs are subject to certain performance conditions and vest three years from original grant date. The unamortized costs of employer contributions to the Company’s share bonus program are included in other long-term assets .
Financial instruments	FINANCIAL INSTRUMENTS The Company classifies its financial instruments into one of the following categories: financial assets at amortized cost; financial liabilities at amortized cost; and fair value through profit or loss. All financial instruments are measured at fair value on initial recognition. Measurement in subsequent periods is dependent on the classification of the respective financial instrument. Fair value through profit or loss financial instruments are subsequently measured at fair value with changes in fair value recognized in net earnings. All other categories of financial instruments are measured at amortized cost using the effective interest method. Cash and cash equivalents, accounts receivable and certain other long-term assets are classified as financial assets at amortized cost since it is the Company’s intention to hold these assets to maturity and the related cash flows are mainly comprised of payments of principal and interest. Investments in publicly traded shares are classified as fair value through profit or loss. Accounts payable, accrued liabilities, certain other long-term liabilities, and long-term debt are classified as financial liabilities at amortized cost. Risk management assets and liabilities are classified as fair value through profit or loss. Financial assets and liabilities are also categorized using a three-level hierarchy that reflects the significance of the inputs used in making fair value measurements for these assets and liabilities. The fair values of financial assets and liabilities included in Level 1 are determined by reference to quoted prices in active markets for identical assets and liabilities. Fair values of financial assets and liabilities in Level 2 are based on inputs other than Level 1 quoted prices that are observable for the asset or liability either directly (as prices) or indirectly (derived from prices). The fair values of Level 3 financial assets and liabilities are not based on observable market data. The disclosure of the fair value hierarchy excludes financial assets and liabilities where book value approximates fair value due to the liquid nature of the asset or liability. Transaction costs in respect of financial instruments at fair value through profit or loss are recognized in net earnings. Transaction costs in respect of other financial instruments are included in the initial measurement of the financial instrument. Impairment of financial assets At each reporting date, the Company assesses whether there is objective evidence that a financial asset is impaired. If such evidence exists, an impairment loss is recognized. Impairment losses on financial assets carried at amortized cost are calculated as the difference between the amortized cost of the financial asset and the present value of the estimated future cash flows, discounted using the instrument’s original effective interest rate. Impairment losses on financial assets carried at amortized cost are reversed in subsequent periods if the amount of the loss decreases and the decrease can be related objectively to an event occurring after the impairment was recognized.
Risk management activities	RISK MANAGEMENT ACTIVITIES The Company periodically uses derivative financial instruments to manage its commodity price, foreign currency and interest rate exposures. These financial instruments are entered into solely for hedging purposes and are not used for speculative purposes. All derivative financial instruments are recognized in the consolidated balance sheets at their estimated fair value. The estimated fair value of derivative financial instruments has been determined based on appropriate internal valuation methodologies and/or third party indications. Fair values determined using valuation models require the use of assumptions concerning the amount and timing of future cash flows, discount rates and credit risk. In determining these assumptions, the Company primarily relied on external, readily-observable market inputs including quoted commodity prices and volatility, interest rate yield curves, and foreign exchange rates. The carrying amount of a risk management liability is adjusted for the Company’s own credit risk. The Company documents all derivative financial instruments that are formally designated as hedging transactions at the inception of the hedging relationship, in accordance with the Company’s risk management policies. The effectiveness of the hedging relationship is evaluated, both at inception of the hedge and on an ongoing basis. The Company periodically enters into commodity price contracts to manage anticipated sales and purchases of crude oil and natural gas in order to protect its cash flow for its capital expenditure programs. The effective portion of changes in the fair value of derivative commodity price contracts formally designated as cash flow hedges is initially recognized in other comprehensive income and is reclassified to risk management activities in net earnings in the same period or periods in which the commodity is sold or purchased. The ineffective portion of changes in the fair value of these designated contracts is recognized in risk management activities in net earnings. All changes in the fair value of non-designated crude oil and natural gas commodity price contracts are recognized in risk management activities in net earnings. The Company periodically enters into interest rate swap contracts to manage its fixed to floating interest rate mix on certain of its long-term debt. The interest rate swap contracts require the periodic exchange of payments without the exchange of the notional principal amounts on which the payments are based. Changes in the fair value of interest rate swap contracts designated as fair value hedges and corresponding changes in the fair value of the hedged long-term debt are recognized in interest expense in net earnings. Changes in the fair value of non-designated interest rate swap contracts are recognized in risk management activities in net earnings. Upon termination of an interest rate swap designated as a fair value hedge, the interest rate swap is derecognized in the consolidated balance sheets and the related long-term debt hedged is no longer revalued for subsequent changes in fair value due to interest rates changes. The fair value adjustment due to interest rates on the long-term debt at the date of termination of the interest rate swap is amortized to interest expense over the remaining term of the long-term debt. Cross currency swap contracts are periodically used to manage currency exposure on US dollar denominated long-term debt. The cross currency swap contracts require the periodic exchange of payments with the exchange at maturity of notional principal amounts on which the payments are based. Changes in the fair value of the foreign exchange component of cross currency swap contracts designated as cash flow hedges related to the notional principal amounts are recognized in foreign exchange gains and losses in net earnings. The effective portion of changes in the fair value of the interest rate component of cross currency swap contracts designated as cash flow hedges is initially recognized in other comprehensive income and is reclassified to interest expense when the hedged item is recognized in net earnings, with the ineffective portion recognized in risk management activities in net earnings. Changes in the fair value of non-designated cross currency swap contracts are recognized in risk management activities in net earnings. Realized gains or losses on the termination of financial instruments that have been designated as cash flow hedges are deferred under accumulated other comprehensive income and amortized into net earnings in the periods in which the underlying hedged items are recognized. In the event a designated hedged item is sold, extinguished or matures prior to the termination of the related derivative instrument, any unrealized derivative gain or loss is recognized in net earnings. Realized gains or losses on the termination of financial instruments that have not been designated as hedges are recognized in net earnings. Foreign currency forward contracts are periodically used to manage foreign currency cash requirements. The foreign currency forward contracts involve the purchase or sale of an agreed upon amount of US dollars at a specified future date at forward exchange rates. Changes in the fair value of foreign currency forward contracts designated as cash flow hedges are initially recorded in other comprehensive income and are reclassified to foreign exchange gains and losses when the hedged item is recognized in net earnings. Changes in the fair value of non-designated foreign currency forward contracts are recognized in risk management activities in net earnings. Embedded derivatives are derivatives that are included in a non-derivative host contract. Embedded derivatives are recorded at fair value separately from the host contract when their economic characteristics and risks are not clearly and closely related to the host contract, except when the host contract is an asset.
Comprehensive income	COMPREHENSIVE INCOME Comprehensive income is comprised of the Company’s net earnings and other comprehensive income. Other comprehensive income includes the effective portion of changes in the fair value of derivative financial instruments designated as cash flow hedges and foreign currency translation gains and losses arising from the net investment in foreign operations that do not have a Canadian dollar functional currency. Other comprehensive income is shown net of related income taxes.
Per common share amounts	PER COMMON SHARE AMOUNTS The Company calculates basic earnings per common share by dividing net earnings by the weighted average number of common shares outstanding during the period. As the Company’s Option Plan allows for the settlement of stock options in either cash or shares at the option of the holder, diluted earnings per common share is calculated using the more dilutive of cash settlement or share settlement under the treasury stock method.
Share capital	SHARE CAPITAL Common shares are classified as equity. Costs directly attributable to the issue of new shares or options are included in equity as a deduction from proceeds, net of tax. When the Company acquires its own common shares, share capital is reduced by the average carrying value of the shares purchased. The excess of the purchase price over the average carrying value is recognized as a reduction of retained earnings. Shares are cancelled upon purchase.
Dividends	DIVIDENDS Dividends on common shares are recognized in the Company’s financial statements in the period in which the dividends are declared by the Board of Directors.
Accounting standards issued but not yet applied	In October 2017, the IASB issued amendments to IAS 28 “Investments in Associates and Joint Ventures” to clarify that the impairment provisions in IFRS 9 apply to financial instruments in an associate or joint venture that are not accounted for using the equity method, including long-term interests that form part of the net investment in the associate or joint venture. The amendments are effective January 1, 2019 with earlier adoption permitted. The amendments are required to be adopted retrospectively. The Company is assessing the impact of the amendments on its consolidated financial statements. In June 2017 , the IASB issued IFRIC 23 "Uncertainty over Income Tax Treatments". The interpretation provides guidance on how to reflect the effects of uncertainty in accounting for income taxes where IAS 12 is unclear. The interpretation is effective January 1, 2019 . The Company is assessing the impact of this interpretation on its consolidated financial statements. In January 2016, the IASB issued IFRS 16 “Leases”, which provides guidance on accounting for leases. The new standard replaces IAS 17 “Leases” and related interpretations. IFRS 16 eliminates the distinction between operating leases and financing leases for lessees. The new standard is effective January 1, 2019 with earlier adoption permitted providing that IFRS 15 has been adopted. The new standard is required to be applied retrospectively, with a policy alternative of restating comparative prior periods or recognizing the cumulative adjustment in opening retained earnings at the date of adoption. The Company is assessing the impact of this standard on its consolidated financial statements. IFRS 15 "Revenue from Contracts with Customers" In May 2014, the IASB issued IFRS 15 “Revenue from Contracts with Customers” to provide guidance on the recognition of revenue and cash flows arising from an entity’s contracts with customers, and related disclosures. The new standard replaces several existing standards related to recognition of revenue and states that revenue should be recognized as performance obligations related to the goods or services delivered are settled. IFRS 15 also provides revenue accounting guidance for contract modifications and multiple-element contracts and prescribes additional disclosure requirements. In 2015, the IASB deferred the effective date for the new standard to January 1, 2018. The new standard is required to be adopted retrospectively, with earlier adoption permitted. Effective January 1, 2018, the Company retrospectively adopted IFRS 15. Adoption of the new standard did not have a significant impact on the Company’s recognition and measurement of revenue; however, it will require certain additional disclosures. Upon adoption of IFRS 15, the Company applied the practical expedient such that contracts that were completed in the comparative periods have not been restated. IFRS 9 "Financial Instruments" Effective January 1, 2014, the Company adopted the version of IFRS 9 “Financial Instruments” issued November 2013. In July 2014, the IASB issued amendments to IFRS 9 to include accounting guidance to assess and recognize impairment losses on financial assets based on an expected loss model. The amendments are effective January 1, 2018 and are required to be adopted retrospectively. Effective January 1, 2018, the Company adopted the amendment to IFRS 9 and elected to apply the limited exemption in IFRS 9 relating to transition for impairment. Adoption of the amendment did not have a significant impact on the Company’s previous accounting for impairment of financial assets.
Critical accounting estimates and judgements	The Company has made estimates, assumptions and judgements regarding certain assets, liabilities, revenues and expenses in the preparation of the consolidated financial statements, primarily related to unsettled transactions and events as of the date of the consolidated financial statements. Accordingly, actual results may differ from estimated amounts. The estimates, assumptions and judgements that have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year are addressed below. (A) Crude Oil and Natural Gas Reserves Purchase price allocations, depletion, depreciation and amortization, asset retirement obligations, and amounts used in impairment calculations are based on estimates of crude oil and natural gas reserves. Reserves estimates are based on engineering data, estimated future prices and production costs, expected future rates of production, and the timing and amount of future development expenditures, all of which are subject to many uncertainties, interpretations and judgements. The Company expects that, over time, its reserves estimates will be revised upward or downward based on updated information. (B) Asset Retirement Obligations The Company provides for asset retirement obligations on its property, plant and equipment based on current legislation and operating practices. Estimated future costs include assumptions of dates of future abandonment and technological advances and estimates of future inflation rates and discount rates. Actual costs may vary from the estimated provision due to changes in environmental legislation, the impact of inflation, changes in technology, changes in operating practices, and changes in the date of abandonment due to changes in reserves life. These differences may have a material impact on the estimated provision. (C) Income Taxes The Company is subject to income taxes in numerous legal jurisdictions. Accounting for income taxes requires the Company to interpret frequently changing laws and regulations, including changing income tax rates, and make certain judgements with respect to the application of tax law, estimating the timing of temporary difference reversals, and estimating the realizability of tax assets. There are many transactions and calculations for which the ultimate tax determination is uncertain. The Company recognizes a liability for a tax filing position based on its assessment of the probability that additional taxes may ultimately be due. (D) Fair Value of Derivatives and Other Financial Instruments The fair value of financial instruments that are not traded in an active market is determined using valuation techniques. The Company uses its judgement to select a variety of methods and make assumptions that are primarily based on market conditions existing at the end of each reporting period. The Company uses directly and indirectly observable inputs in measuring the value of financial instruments that are not traded in active markets, including quoted commodity prices and volatility, interest rate yield curves and foreign exchange rates. (E) Purchase Price Allocations Purchase prices related to business combinations are allocated to the underlying acquired assets and liabilities based on their estimated fair value at the time of acquisition. The determination of fair value requires the Company to make estimates, assumptions and judgements regarding future events. The allocation process is inherently subjective and impacts the amounts assigned to individually identifiable assets and liabilities, including the fair value of crude oil and natural gas properties together with deferred income tax effects. As a result, the purchase price allocation impacts the Company’s reported assets and liabilities and future net earnings due to the impact on future depletion, depreciation, and amortization expense and impairment tests. (F) Share-Based Compensation The Company has made various assumptions in estimating the fair values of stock options granted under its Option Plan, including expected volatility, expected exercise timing and future forfeiture rates. At each period end, stock options outstanding are remeasured for changes in the fair value of the liability. (G) Identification of CGUs CGUs are defined as the lowest grouping of integrated assets that generate identifiable cash inflows that are largely independent of the cash inflows of other assets or groups of assets. The classification of assets into CGUs requires significant judgement and interpretations with respect to the integration between assets, the existence of active markets, shared infrastructures, and the way in which management monitors the Company’s operations. (H) Impairment of Assets The recoverable amount of a CGU or an individual asset has been determined as the higher of the CGUs' or the asset’s fair value less costs of disposal and its value in use. These calculations require the use of estimates and assumptions and are subject to change as new information becomes available, including information on future commodity prices, expected production volumes, quantity of reserves, asset retirement obligations, future development and operating costs, after-tax discount rates currently ranging from 10% to 12% , and income taxes. Changes in assumptions used in determining the recoverable amount could affect the carrying value of the related assets and CGUs. (I) Contingencies Contingencies are subject to measurement uncertainty as the related financial impact will only be confirmed by the outcome of a future event. The assessment of contingencies requires the application of judgements and estimates including the determination of whether a present obligation exists and the reliable estimation of the timing and amount of cash flows required to settle the contingency.

INVENTORY (Tables)

INVENTORY (Tables)	12 Months Ended
	Dec. 31, 2017
Inventories [Abstract]
Schedule of Inventory	2017 2016 Product inventory $ 285 $ 263 Materials and supplies 609 426 $ 894 $ 689

EXPLORATION AND EVALUATION AS32

EXPLORATION AND EVALUATION ASSETS (Tables)	12 Months Ended
	Dec. 31, 2017
Exploration For And Evaluation Of Mineral Resources [Abstract]
Detailed information about exploration and evaluation assets	Exploration and Production Oil Sands Mining and Upgrading Total North America North Sea Offshore Africa Cost At December 31, 2015 $ 2,500 $ — $ 86 $ — $ 2,586 Additions 20 — 9 — 29 Transfers to property, plant and equipment (211 ) — — — (211 ) Disposals/derecognitions (3 ) — (18 ) — (21 ) Foreign exchange adjustments — — (1 ) — (1 ) At December 31, 2016 2,306 — 76 — 2,382 Additions 144 — 15 — 159 Acquisition of AOSP and other assets (note 7) 31 — — 259 290 Transfers to property, plant and equipment (198 ) — — — (198 ) Disposals/derecognitions (1 ) — — — (1 ) At December 31, 2017 $ 2,282 $ — $ 91 $ 259 $ 2,632

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2017
Property, plant and equipment [abstract]
Detailed information about property, plant and equipment	Exploration and Production Oil Sands Mining and Upgrading Midstream Head Office Total North America North Sea Offshore Africa Cost At December 31, 2015 $ 60,540 $ 7,414 $ 5,173 $ 24,343 $ 577 $ 378 $ 98,425 Additions 1,462 186 116 2,822 6 17 4,609 Transfers from E&E assets 211 — — — — — 211 Disposals/derecognitions (566 ) — — (127 ) (349 ) — (1,042 ) Foreign exchange adjustments and other — (220 ) (157 ) — — — (377 ) At December 31, 2016 61,647 7,380 5,132 27,038 234 395 101,826 Additions (1) 3,003 255 101 1,660 194 19 5,232 Acquisition of AOSP and other assets (note 7) 349 — — 13,832 — — 14,181 Transfers from E&E assets 198 — — — — — 198 Disposals/derecognitions (381 ) — — (446 ) — — (827 ) Foreign exchange adjustments and other — (509 ) (352 ) — — — (861 ) At December 31, 2017 $ 64,816 $ 7,126 $ 4,881 $ 42,084 $ 428 $ 414 $ 119,749 Accumulated depletion and depreciation At December 31, 2015 $ 35,347 $ 5,264 $ 3,659 $ 2,294 $ 132 $ 254 $ 46,950 Expense 3,440 457 243 662 11 27 4,840 Disposals/derecognitions (486 ) — — (127 ) (28 ) — (641 ) Foreign exchange adjustments and other 10 (137 ) (105 ) (1 ) — — (233 ) At December 31, 2016 38,311 5,584 3,797 2,828 115 281 50,916 Expense 3,220 509 205 1,220 9 23 5,186 Disposals/derecognitions (381 ) — — (446 ) — — (827 ) Foreign exchange adjustments and other 1 (440 ) (283 ) 26 — — (696 ) At December 31, 2017 $ 41,151 $ 5,653 $ 3,719 $ 3,628 $ 124 $ 304 $ 54,579 Net book value - at December 31, 2017 $ 23,665 $ 1,473 $ 1,162 $ 38,456 $ 304 $ 110 $ 65,170 - at December 31, 2016 $ 23,336 $ 1,796 $ 1,335 $ 24,210 $ 119 $ 114 $ 50,910 (1) Additions in Midstream include the revaluation of a previously held joint interest in certain pipeline system assets. Project costs not subject to depletion and depreciation 2017 2016 Kirby Thermal Oil Sands – North $ 944 $ 846

ACQUISITION OF INTERESTS IN T34

ACQUISITION OF INTERESTS IN THE ATHABASCA OIL SANDS PROJECT AND OTHER ASSETS (Tables)	12 Months Ended
	Dec. 31, 2017
Business Combinations1 [Abstract]
Summary of net assets acquired and liabilities assumed	The following provides a summary of the net assets acquired and (liabilities) assumed relating to the acquisition: Cash $ 93 Other working capital 291 Property, plant and equipment 14,181 Exploration and evaluation assets 290 Asset retirement obligations (721 ) Other long-term liabilities (73 ) Deferred income taxes (1,287 ) Net assets acquired $ 12,774 Total purchase consideration 12,541 Gain on acquisition before transaction costs $ 233

INVESTMENTS (Tables)

INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2017
Financial Instruments [Abstract]
Summary of investments	The loss (gain) from the investment in Inter Pipeline was comprised as follows: 2017 2016 2015 Fair value loss from Inter Pipeline $ 23 $ — $ — Dividend income from Inter Pipeline (10 ) (1 ) — $ 13 $ (1 ) $ — The (gain) loss from the investment in PrairieSky was comprised as follows: 2017 2016 2015 Fair value (gain) loss from PrairieSky $ (3 ) $ (292 ) $ 11 Dividend income from PrairieSky (17 ) (27 ) (5 ) $ (20 ) $ (319 ) $ 6 As at December 31, 2017 and 2016 , the Company had the following investments: 2017 2016 Investment in PrairieSky Royalty Ltd. $ 726 $ 723 Investment in Inter Pipeline Ltd. 167 190 $ 893 $ 913

OTHER LONG-TERM ASSETS (Tables)

OTHER LONG-TERM ASSETS (Tables)	12 Months Ended
	Dec. 31, 2017
Subclassifications of assets, liabilities and equities [abstract]
Disclosure of other long-term assets	2017 2016 Investment in North West Redwater Partnership $ 292 $ 261 North West Redwater Partnership subordinated debt (1) 510 385 Risk Management (note 18) 204 489 Other 241 168 1,247 1,303 Less: current portion 79 283 $ 1,168 $ 1,020
Summary of assets, liabilities, partners' equity and equity (income) loss related to joint venture	The assets, liabilities, partners’ equity and equity income related to Redwater Partnership and the Company’s 50% interest at December 31, 2017 and 2016 were comprised as follows: 2017 2016 Redwater Partnership Company Redwater Partnership Company Current assets $ 330 $ 165 $ 96 $ 48 Non-current assets $ 10,540 $ 5,270 $ 8,258 $ 4,129 Current liabilities $ 2,476 $ 1,238 $ 572 $ 286 Non-current liabilities $ 7,810 $ 3,905 $ 7,260 $ 3,630 Partners’ equity $ 584 $ 292 $ 522 $ 261 Equity income $ (62 ) $ (31 ) $ (14 ) $ (7 )

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2017
Financial Instruments [Abstract]
Summary of long-term debt	2017 2016 Canadian dollar denominated debt, unsecured Bank credit facilities $ 3,544 $ 2,758 Medium-term notes 3.05% debentures due June 19, 2019 500 500 2.60% debentures due December 3, 2019 500 500 2.05% debentures due June 1, 2020 900 — 2.89% debentures due August 14, 2020 1,000 1,000 3.31% debentures due February 11, 2022 1,000 1,000 3.55% debentures due June 3, 2024 500 500 3.42% debentures due December 1, 2026 600 — 4.85% debentures due May 30, 2047 300 — 8,844 6,258 US dollar denominated debt, unsecured Bank credit facilities (December 31, 2017 - US$1,839 million; 2,300 1,213 Commercial paper (December 31, 2017 - US$500 million; December 31, 2016 - US$250 million) 625 336 US dollar debt securities 5.70% due May 15, 2017 (US$1,100 million) — 1,477 1.75% due January 15, 2018 (US$600 million) 751 806 5.90% due February 1, 2018 (US$400 million) 501 537 3.45% due November 15, 2021 (US$500 million) 625 671 2.95% due January 15, 2023 (US$1,000 million) 1,252 — 3.80% due April 15, 2024 (US$500 million) 625 671 3.90% due February 1, 2025 (US$600 million) 751 806 3.85% due June 1, 2027 (US$1,250 million) 1,566 — 7.20% due January 15, 2032 (US$400 million) 501 537 6.45% due June 30, 2033 (US$350 million) 438 470 5.85% due February 1, 2035 (US$350 million) 438 470 6.50% due February 15, 2037 (US$450 million) 563 604 6.25% due March 15, 2038 (US$1,100 million) 1,377 1,477 6.75% due February 1, 2039 (US$400 million) 501 537 4.95% due June 1, 2047 (US$750 million) 939 — 13,753 10,612 Long-term debt before transaction costs and original issue discounts, net 22,597 16,870 Less: original issue discounts, net (1) 18 10 transaction costs (1) (2) 121 55 22,458 16,805 Less: current portion of commercial paper 625 336 current portion of other long-term debt (1) (2) 1,252 1,476 $ 20,581 $ 14,993 (1) The Company has included unamortized original issue discounts and premiums, and directly attributable transaction costs in the carrying amount of the outstanding debt. (2) Transaction costs primarily represent underwriting commissions charged as a percentage of the related debt offerings, as well as legal, rating agency and other professional fees.
Schedule of debt repayments	Scheduled debt repayments are as follows: Year Repayment 2018 $ 2,027 2019 $ 4,228 2020 $ 4,231 2021 $ 760 2022 $ 1,000 Thereafter $ 10,351 The maturity dates for financial liabilities were as follows: Less than 1 year 1 to less than 2 years 2 to less than 5 years Thereafter Accounts payable $ 775 $ — $ — $ — Accrued liabilities $ 2,597 $ — $ — $ — Other long-term liabilities (1) $ 572 $ — $ — $ — Long-term debt (2) (3) $ 2,027 $ 4,228 $ 5,991 $ 10,351 (1) Includes $469 million ( US$375 million ) of deferred purchase consideration payable to Marathon in March 2018. (2) Long-term debt represents principal repayments only and does not reflect interest, original issue discounts and premiums or transaction costs. (3) In addition to the financial liabilities disclosed above, estimated interest and other financing payments related to long-term debt are as follows: less than one year, $842 million ; one to less than two years, $755 million ; two to less than five years, $1,712 million ; and thereafter, $5,384 million . Interest payments were estimated based upon applicable interest and foreign exchange rates as at December 31, 2017 .

OTHER LONG-TERM LIABILITIES (Ta

OTHER LONG-TERM LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2017
Subclassifications of assets, liabilities and equities [abstract]
Disclosure of other long-term liabilities	2017 2016 Asset retirement obligations $ 4,327 $ 3,243 Share-based compensation 414 426 Risk management (note 18) 103 — Other (1) 565 17 5,409 3,686 Less: current portion 1,012 463 $ 4,397 $ 3,223 (1) Included in Other at December 31, 2017 is $469 million ( US$375 million ) of deferred purchase consideration payable to Marathon in March 2018.
Summary of asset retirement obligations	Reconciliations of the discounted asset retirement obligations were as follows: 2017 2016 2015 Balance – beginning of year $ 3,243 $ 2,950 $ 4,221 Liabilities incurred 12 3 7 Liabilities acquired, net 784 30 129 Liabilities settled (274 ) (267 ) (370 ) Asset retirement obligation accretion 164 142 173 Revision of cost, inflation rates and timing estimates (40 ) (68 ) (313 ) Change in discount rate 509 493 (1,150 ) Foreign exchange adjustments (71 ) (40 ) 253 Balance – end of year 4,327 3,243 2,950 Less: current portion 92 95 101 $ 4,235 $ 3,148 $ 2,849 Segmented Asset Retirement Obligations 2017 2016 Exploration and Production North America $ 1,840 $ 1,444 North Sea 755 837 Offshore Africa 245 244 Oil Sands Mining and Upgrading 1,486 717 Midstream 1 1 $ 4,327 $ 3,243
Summary of share-based compensation liability	2017 2016 2015 Balance – beginning of year $ 426 $ 128 $ 203 Share-based compensation expense (recovery) 134 355 (46 ) Cash payment for stock options surrendered (6 ) (7 ) (1 ) Transferred to common shares (154 ) (117 ) (18 ) Charged to (recovered from) Oil Sands Mining and Upgrading, net 14 67 (10 ) Balance – end of year 414 426 128 Less: current portion 348 368 105 $ 66 $ 58 $ 23
Disclosure of weighted average assumptions used	The fair value of stock options outstanding was estimated using the Black-Scholes valuation model with the following weighted average assumptions: 2017 2016 2015 Fair value $ 11.82 $ 11.41 $ 3.06 Share price $ 44.92 $ 42.79 $ 30.22 Expected volatility 27.1% 30.7% 28.6% Expected dividend yield 2.5% 2.3% 3.0% Risk free interest rate 1.8% 0.9% 0.6% Expected forfeiture rate 5.0% 5.0% 4.8% Expected stock option life (1) 4.5 years 4.6 years 4.5 years (1) At original time of grant.

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2017
Income Taxes [Abstract]
Schedule of provision for income tax	The provision for income tax was as follows: Expense (recovery) 2017 2016 2015 Current corporate income tax – North America $ (145 ) $ (377 ) $ 86 Current corporate income tax – North Sea 57 (74 ) (117 ) Current corporate income tax – Offshore Africa 45 22 17 Current PRT (1) – North Sea (132 ) (198 ) (258 ) Other taxes 11 9 11 Current income tax (164 ) (618 ) (261 ) Deferred corporate income tax 586 (106 ) 216 Deferred PRT (1) – North Sea 54 (135 ) 15 Deferred income tax 640 (241 ) 231 Income tax $ 476 $ (859 ) $ (30 ) (1) Petroleum Revenue Tax.
Schedule of provision for income tax reconciliation	The provision for income tax is different from the amount computed by applying the combined statutory Canadian federal and provincial income tax rates to earnings (loss) before taxes. The reasons for the difference are as follows: 2017 2016 2015 Canadian statutory income tax rate 27.0% 27.0% 26.0% Income tax provision at statutory rate $ 776 $ (287 ) $ (173 ) Effect on income taxes of: UK PRT and other taxes (67 ) (324 ) (232 ) Impact of deductible UK PRT and other taxes on corporate income tax 28 131 119 Foreign and domestic tax rate differentials (43 ) (54 ) (157 ) Non-taxable portion of capital gains/losses (86 ) (80 ) 36 Stock options exercised for common shares 33 94 (12 ) Income tax rate and other legislative changes 10 (107 ) 362 Non-taxable gain on corporate acquisitions (63 ) — — Revisions arising from prior year tax filings (3 ) (120 ) 32 Change in unrecognized capital loss carryforward asset (86 ) (80 ) 36 Other (23 ) (32 ) (41 ) Income tax expense (recovery) $ 476 $ (859 ) $ (30 )
Summary of major temporary differences, movements in deferred tax assets and liabilities, and net deferred income tax liability	The following table summarizes the temporary differences that give rise to the net deferred income tax liability: 2017 2016 Deferred income tax liabilities Property, plant and equipment and exploration and evaluation assets $ 12,484 $ 10,259 Unrealized risk management activities 20 62 PRT deduction for corporate income tax 7 29 Investments 96 98 Investment in North West Redwater Partnership 252 222 12,859 10,670 Deferred income tax assets Asset retirement obligations (1,264 ) (983 ) Loss carryforwards (523 ) (390 ) Unrealized foreign exchange loss on long-term debt (29 ) (149 ) Deferred PRT (18 ) (73 ) Other (50 ) (2 ) (1,884 ) (1,597 ) Net deferred income tax liability $ 10,975 $ 9,073 Movements in deferred tax assets and liabilities recognized in net earnings during the year were as follows: 2017 2016 2015 Property, plant and equipment and exploration and evaluation assets $ 541 $ 37 $ (7 ) Timing of partnership items — (261 ) (176 ) Unrealized foreign exchange loss (gain) on long-term debt 120 63 (222 ) Unrealized risk management activities (46 ) (44 ) (5 ) Asset retirement obligations (88 ) (20 ) 522 Loss carryforwards 48 (221 ) (53 ) Investments (2 ) 38 60 Investment in North West Redwater Partnership 30 81 106 Deferred PRT 54 (135 ) 15 PRT deduction for corporate income tax (21 ) 61 (5 ) Other 4 160 (4 ) $ 640 $ (241 ) $ 231 The following table summarizes the movements of the net deferred income tax liability during the year: 2017 2016 2015 Balance – beginning of year $ 9,073 $ 9,344 $ 8,970 Deferred income tax expense (recovery) 640 (241 ) 231 Deferred income tax expense (recovery) included in other comprehensive income 4 (5 ) (4 ) Foreign exchange adjustments (29 ) (25 ) 147 Business combinations (note 7) 1,287 — — Balance – end of year $ 10,975 $ 9,073 $ 9,344

SHARE CAPITAL (Tables)

SHARE CAPITAL (Tables)	12 Months Ended
	Dec. 31, 2017
Share Capital, Reserves And Other Equity Interest [Abstract]
Summary of outstanding common stock	2017 2016 Issued Common shares Number of shares (thousands) Amount Number of shares Amount Balance – beginning of year 1,110,952 $ 4,671 1,094,668 $ 4,541 Issued for the acquisition of AOSP and other assets (note 7) 97,561 3,818 — — Issued upon exercise of stock options 14,256 466 16,284 559 Previously recognized liability on stock options exercised for common shares — 154 — 117 Return of capital on PrairieSky Royalty Ltd. share distribution (note 8) — — — (546 ) Balance – end of year 1,222,769 $ 9,109 1,110,952 $ 4,671
Summary of stock option activity	The following table summarizes information relating to stock options outstanding at December 31, 2017 and 2016 : 2017 2016 Stock options (thousands) Weighted average exercise price Stock options (thousands) Weighted Outstanding – beginning of year 58,299 $ 34.22 74,615 $ 34.88 Granted 16,052 $ 42.07 11,002 $ 34.97 Surrendered for cash settlement (626 ) $ 33.18 (817 ) $ 34.47 Exercised for common shares (14,256 ) $ 32.66 (16,284 ) $ 34.31 Forfeited (3,433 ) $ 37.53 (10,217 ) $ 39.66 Outstanding – end of year 56,036 $ 36.67 58,299 $ 34.22 Exercisable – end of year 18,282 $ 34.25 20,747 $ 33.75
Summary of range of exercise prices of stock options outstanding	The range of exercise prices of stock options outstanding and exercisable at December 31, 2017 was as follows: Stock options outstanding Stock options exercisable Range of exercise prices Stock options outstanding (thousands) Weighted average remaining term (years) Weighted average exercise price Stock options exercisable (thousands) Weighted average exercise price $22.90 - $24.99 3,657 3.03 $ 22.90 1,116 $ 22.90 $25.00 - $29.99 8,390 2.34 $ 28.72 3,967 $ 28.57 $30.00 - $34.99 10,047 1.61 $ 33.31 5,557 $ 33.49 $35.00 - $39.99 13,523 3.29 $ 37.21 4,190 $ 35.88 $40.00 - $44.99 19,417 4.15 $ 43.60 3,118 $ 43.55 $45.00 - $46.74 1,002 3.63 $ 45.61 334 $ 45.09 56,036 3.13 $ 36.67 18,282 $ 34.25

ACCUMULATED OTHER COMPREHENSI41

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	12 Months Ended
	Dec. 31, 2017
Analysis Of Other Comprehensive Income By Item [Abstract]
Components of Accumulated Other Comprehensive Income (Loss), Net of Taxes	The components of accumulated other comprehensive income (loss), net of taxes, were as follows: 2017 2016 Derivative financial instruments designated as cash flow hedges $ 47 $ 27 Foreign currency translation adjustment (115 ) 43 $ (68 ) $ 70

CAPITAL DISCLOSURES (Tables)

CAPITAL DISCLOSURES (Tables)	12 Months Ended
	Dec. 31, 2017
Corporate Information And Statement Of IFRS Compliance [Abstract]
Disclosure of detailed information about capital	2017 2016 Long-term debt, net (1) $ 22,321 $ 16,788 Total shareholders’ equity $ 31,653 $ 26,267 Debt to book capitalization 41% 39% (1) Includes the current portion of long-term debt, net of cash and cash equivalents.

NET EARNINGS (LOSS) PER COMMO43

NET EARNINGS (LOSS) PER COMMON SHARE (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings per share [abstract]
Net earnings (loss) per common share	2017 2016 2015 Weighted average common shares outstanding – basic (thousands of shares) 1,175,094 1,100,471 1,093,862 Effect of dilutive stock options (thousands of shares) 7,729 — — Weighted average common shares outstanding – diluted (thousands of shares) 1,182,823 1,100,471 1,093,862 Net earnings (loss) $ 2,397 $ (204 ) $ (637 ) Net earnings (loss) per common share – basic $ 2.04 $ (0.19 ) $ (0.58 ) – diluted $ 2.03 $ (0.19 ) $ (0.58 )

INTEREST AND OTHER FINANCING 44

INTEREST AND OTHER FINANCING EXPENSE (Tables)	12 Months Ended
	Dec. 31, 2017
Borrowing costs [abstract]
Disclosure of interest and other financing expense	2017 2016 2015 Interest and other financing expense: Long-term debt $ 810 $ 664 $ 618 Other (1) — — 1 810 664 619 Less: amounts capitalized on qualifying assets 82 233 244 Total interest and other financing expense 728 431 375 Total interest income (97 ) (48 ) (53 ) Net interest and other financing expense $ 631 $ 383 $ 322 (1) Includes the fair value impact of interest rate swaps on US dollar debt securities.

FINANCIAL INSTRUMENTS (Tables)

FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2017
Financial Instruments [Abstract]
Schedule of financial assets	The carrying amounts of the Company’s financial instruments by category were as follows: 2017 Asset (liability) Financial assets at amortized cost Fair value through profit or loss Derivatives used for hedging Financial liabilities at amortized cost Total Accounts receivable $ 2,397 $ — $ — $ — $ 2,397 Investments — 893 — — 893 Other long-term assets 510 — 204 — 714 Accounts payable — — — (775 ) (775 ) Accrued liabilities — — — (2,597 ) (2,597 ) Other long-term liabilities (1) — (38 ) (65 ) (469 ) (572 ) Long-term debt (2) — — — (22,458 ) (22,458 ) $ 2,907 $ 855 $ 139 $ (26,299 ) $ (22,398 ) 2016 Asset (liability) Financial assets at amortized cost Fair value through profit or loss Derivatives used for hedging Financial liabilities at amortized cost Total Accounts receivable $ 1,434 $ — $ — $ — $ 1,434 Investments — 913 — — 913 Other long-term assets 385 4 485 — 874 Accounts payable — — — (595 ) (595 ) Accrued liabilities — — — (2,222 ) (2,222 ) Long-term debt (2) — — — (16,805 ) (16,805 ) $ 1,819 $ 917 $ 485 $ (19,622 ) $ (16,401 ) (1) Includes $469 million ( US$375 million ) of deferred purchase consideration payable to Marathon in March 2018. (2) Includes the current portion of long-term debt. The fair values of the Company’s investments, recurring other long-term assets (liabilities) and fixed rate long-term debt are outlined below: 2017 Carrying amount Fair value Asset (liability) (1) (2) Level 1 Level 2 Level 3 Investments (3) $ 893 $ 893 $ — $ — Other long-term assets (4) $ 714 $ — $ 204 $ 510 Other long-term liabilities $ (103 ) $ — $ (103 ) $ — Fixed rate long-term debt (5) (6) $ (15,989 ) $ (17,259 ) $ — $ — 2016 Carrying amount Fair value Asset (liability) (1) (2) Level 1 Level 2 Level 3 Investments (3) $ 913 $ 913 $ — $ — Other long-term assets (4) $ 874 $ — $ 489 $ 385 Fixed rate long-term debt (5) (6) $ (12,498 ) $ (13,217 ) $ — $ — (1) Excludes financial assets and liabilities where the carrying amount approximates fair value due to the liquid nature of the asset or liability (cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities, and deferred purchase consideration payable to Marathon in March 2018). (2) There were no transfers between Level 1, 2 and 3 financial instruments. (3) The fair value of the investments are based on quoted market prices. (4) The fair value of Redwater Partnership subordinated debt is based on the present value of future cash receipts. (5) The fair value of fixed rate long-term debt has been determined based on quoted market prices. (6) Includes the current portion of fixed rate long-term debt.
Schedule of financial liabilities	The carrying amounts of the Company’s financial instruments by category were as follows: 2017 Asset (liability) Financial assets at amortized cost Fair value through profit or loss Derivatives used for hedging Financial liabilities at amortized cost Total Accounts receivable $ 2,397 $ — $ — $ — $ 2,397 Investments — 893 — — 893 Other long-term assets 510 — 204 — 714 Accounts payable — — — (775 ) (775 ) Accrued liabilities — — — (2,597 ) (2,597 ) Other long-term liabilities (1) — (38 ) (65 ) (469 ) (572 ) Long-term debt (2) — — — (22,458 ) (22,458 ) $ 2,907 $ 855 $ 139 $ (26,299 ) $ (22,398 ) 2016 Asset (liability) Financial assets at amortized cost Fair value through profit or loss Derivatives used for hedging Financial liabilities at amortized cost Total Accounts receivable $ 1,434 $ — $ — $ — $ 1,434 Investments — 913 — — 913 Other long-term assets 385 4 485 — 874 Accounts payable — — — (595 ) (595 ) Accrued liabilities — — — (2,222 ) (2,222 ) Long-term debt (2) — — — (16,805 ) (16,805 ) $ 1,819 $ 917 $ 485 $ (19,622 ) $ (16,401 ) (1) Includes $469 million ( US$375 million ) of deferred purchase consideration payable to Marathon in March 2018. (2) Includes the current portion of long-term debt. The fair values of the Company’s investments, recurring other long-term assets (liabilities) and fixed rate long-term debt are outlined below: 2017 Carrying amount Fair value Asset (liability) (1) (2) Level 1 Level 2 Level 3 Investments (3) $ 893 $ 893 $ — $ — Other long-term assets (4) $ 714 $ — $ 204 $ 510 Other long-term liabilities $ (103 ) $ — $ (103 ) $ — Fixed rate long-term debt (5) (6) $ (15,989 ) $ (17,259 ) $ — $ — 2016 Carrying amount Fair value Asset (liability) (1) (2) Level 1 Level 2 Level 3 Investments (3) $ 913 $ 913 $ — $ — Other long-term assets (4) $ 874 $ — $ 489 $ 385 Fixed rate long-term debt (5) (6) $ (12,498 ) $ (13,217 ) $ — $ — (1) Excludes financial assets and liabilities where the carrying amount approximates fair value due to the liquid nature of the asset or liability (cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities, and deferred purchase consideration payable to Marathon in March 2018). (2) There were no transfers between Level 1, 2 and 3 financial instruments. (3) The fair value of the investments are based on quoted market prices. (4) The fair value of Redwater Partnership subordinated debt is based on the present value of future cash receipts. (5) The fair value of fixed rate long-term debt has been determined based on quoted market prices. (6) Includes the current portion of fixed rate long-term debt.
Schedule of derivative financial instruments	At December 31, 2017 the Company had the following cross currency swap contracts outstanding: Remaining term Amount Exchange rate (US$/C$) Interest rate (US$) Interest rate (C$) Cross currency Swaps Jan 2018 — Nov 2021 US$500 1.022 3.45 % 3.96 % Jan 2018 — Mar 2038 US$550 1.170 6.25 % 5.76 %
Schedule of information about financial instruments	The following provides a summary of the carrying amounts of derivative financial instruments held and a reconciliation to the Company’s consolidated balance sheets. Asset (liability) 2017 2016 Derivatives held for trading Foreign currency forward contracts $ (38 ) $ 10 Natural gas AECO swaps — (6 ) Cash flow hedges Foreign currency forward contracts (71 ) 16 Cross currency swaps 210 469 $ 101 $ 489 Included within: Current portion of other long-term (liabilities) assets $ (103 ) $ 222 Other long-term assets 204 267 $ 101 $ 489 Net loss (gain) from risk management activities for the years ended December 31 were as follows: 2017 2016 2015 Net realized risk management (gain) loss $ (2 ) $ 8 $ (843 ) Net unrealized risk management loss 37 25 374 $ 35 $ 33 $ (469 ) The changes in estimated fair values of derivative financial instruments included in the risk management asset were recognized in the financial statements as follows: Asset (liability) 2017 2016 Balance – beginning of year $ 489 $ 854 Net change in fair value of outstanding derivative financial instruments recognized in: Risk management activities (37 ) (25 ) Foreign exchange (375 ) (304 ) Other comprehensive income (loss) 24 (36 ) Balance – end of year 101 489 Less: current portion (103 ) 222 $ 204 $ 267
Disclosure of financial instrument sensitivities	In addition, changes in fair value generally cannot be extrapolated because the relationship of a change in an assumption to the change in fair value may not be linear. Increase (decrease) to net earnings (Increase) decrease to other comprehensive loss Interest rate risk Increase interest rate 1% $ (42 ) $ (16 ) Decrease interest rate 1% $ 42 $ 19 Foreign currency exchange rate risk Increase exchange rate by US$0.01 $ (105 ) $ — Decrease exchange rate by US$0.01 $ 101 $ —
Schedule of maturity dates for financial liabilities	Scheduled debt repayments are as follows: Year Repayment 2018 $ 2,027 2019 $ 4,228 2020 $ 4,231 2021 $ 760 2022 $ 1,000 Thereafter $ 10,351 The maturity dates for financial liabilities were as follows: Less than 1 year 1 to less than 2 years 2 to less than 5 years Thereafter Accounts payable $ 775 $ — $ — $ — Accrued liabilities $ 2,597 $ — $ — $ — Other long-term liabilities (1) $ 572 $ — $ — $ — Long-term debt (2) (3) $ 2,027 $ 4,228 $ 5,991 $ 10,351 (1) Includes $469 million ( US$375 million ) of deferred purchase consideration payable to Marathon in March 2018. (2) Long-term debt represents principal repayments only and does not reflect interest, original issue discounts and premiums or transaction costs. (3) In addition to the financial liabilities disclosed above, estimated interest and other financing payments related to long-term debt are as follows: less than one year, $842 million ; one to less than two years, $755 million ; two to less than five years, $1,712 million ; and thereafter, $5,384 million . Interest payments were estimated based upon applicable interest and foreign exchange rates as at December 31, 2017 .

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2017
Other Provisions, Contingent Liabilities And Contingent Assets [Abstract]
Disclosure of future payments	The Company has committed to certain payments as follows: 2018 2019 2020 2021 2022 Thereafter Product transportation and pipeline $ 680 $ 584 $ 526 $ 482 $ 422 $ 3,868 Offshore equipment operating leases $ 181 $ 92 $ 70 $ 68 $ 8 $ — Office leases $ 43 $ 42 $ 42 $ 39 $ 30 $ 118 Other (1) $ 87 $ 41 $ 40 $ 39 $ 43 $ 333 (1) In addition to the amounts disclosed above, beginning on the earlier of the commercial operations date of the Redwater refinery and June 1, 2018, the Company is unconditionally obligated to pay its 25% pro rata share of the debt portion of the monthly cost of service toll, including interest, fees and principal repayments, of the syndicated credit facility and bonds, over the tolling period of 30 years . See Note 9.

SUPPLEMENTAL DISCLOSURE OF CA47

SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2017
Statement Of Cash Flows, Additional Disclosures [Abstract]
Schedule Of Cash Flow Supplemental Disclosures	2017 2016 2015 Changes in non-cash working capital Accounts receivable $ (977 ) $ (142 ) $ 615 Current income tax assets 527 (165 ) (447 ) Inventory 81 (79 ) 142 Prepaids and other (28 ) 14 11 Accounts payable 175 31 7 Accrued liabilities 365 (116 ) (981 ) Other long-term liabilities (1) 469 — — Net changes in non-cash working capital $ 612 $ (457 ) $ (653 ) Relating to: Operating activities $ 299 $ (542 ) $ 239 Financing activities — — (40 ) Investing activities 313 85 (852 ) $ 612 $ (457 ) $ (653 ) 2017 2016 2015 Expenditures on exploration and evaluation assets $ 159 $ 29 $ 180 Net proceeds on sale of exploration and evaluation assets (2) (35 ) (35 ) (416 ) Net expenditures (proceeds) on exploration and evaluation assets $ 124 $ (6 ) $ (236 ) Expenditures on property, plant and equipment $ 4,574 $ 4,152 $ 5,118 Net proceeds on sale of property, plant and equipment (2) (3) — (349 ) (414 ) Net expenditures on property, plant and equipment $ 4,574 $ 3,803 $ 4,704 (1) Included in other long-term liabilities at December 31, 2017 is $469 million ( US$375 million ) of deferred purchase consideration payable to Marathon in March 2018. (2) Net proceeds on exploration and evaluation assets and net expenditures on property, plant and equipment in 2015 exclude non-cash share consideration of $985 million received from PrairieSky on the disposition of royalty income assets. (3) Net expenditures on property, plant and equipment in 2016 exclude non-cash share consideration of $190 million received from Inter Pipeline on the disposition of the Company's interest in the Cold Lake Pipeline.
Reconciliation of liabilities arising from financing activities	The following table summarizes movements in the Company's liabilities arising from financing activities for the year ended December 31, 2017: Long-term debt Cash flow hedges on US dollar debt securities Liabilities from financing activities At December 31, 2016 $ 16,805 $ (485 ) $ 16,320 Changes from financing cash flows: Issue of long-term debt, net (1) 6,622 — 6,622 Settlement of hedge instruments, net — 124 124 Changes in foreign exchange and fair value (2) (969 ) 222 (747 ) At December 31, 2017 $ 22,458 $ (139 ) $ 22,319 (1) Includes original issue discounts and premiums, and directly attributable transaction costs. (2) Includes foreign exchange (gain) loss, changes in the fair value of cash flow hedges on US dollar debt and the amortization of original issue discounts and premiums and directly attributable transaction costs.

SEGMENTED INFORMATION (Tables)

SEGMENTED INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2017
Operating Segments [Abstract]
Disclosure of operating segments	Oil Sands Mining and Upgrading Midstream Inter–segment elimination and other Total 2017 2016 2015 2017 2016 2015 2017 2016 2015 2017 2016 2015 $ 7,072 $ 2,657 $ 2,764 $ 102 $ 114 $ 136 $ (82 ) $ (55 ) $ (75 ) $ 17,669 $ 11,098 $ 13,167 (167 ) (24 ) (49 ) — — — — — — (1,018 ) (575 ) (804 ) 6,905 2,633 2,715 102 114 136 (82 ) (55 ) (75 ) 16,651 10,523 12,363 2,600 1,292 1,332 16 25 32 (8 ) (7 ) (8 ) 5,596 4,099 4,726 679 80 82 — — — (85 ) (68 ) (75 ) 2,917 2,003 2,379 1,220 662 562 9 11 12 — — — 5,186 4,858 5,483 48 29 31 — — — — — — 164 142 173 — — — — — — — — — (2 ) 8 (843 ) (230 ) — — (114 ) (218 ) — — — — (379 ) (250 ) (739 ) — — — (31 ) (7 ) 44 — — — (38 ) (327 ) 50 4,317 2,063 2,007 (120 ) (189 ) 88 (93 ) (75 ) (83 ) 13,444 10,533 11,229 $ 2,588 $ 570 $ 708 $ 222 $ 303 $ 48 $ 11 $ 20 $ 8 3,207 (10 ) 1,134 319 345 390 134 355 (46 ) 631 383 322 37 25 374 (787 ) (55 ) 761 334 1,053 1,801 2,873 (1,063 ) (667 ) (164 ) (618 ) (261 ) 640 (241 ) 231 $ 2,397 $ (204 ) $ (637 ) North America North Sea Offshore Africa (millions of Canadian dollars) 2017 2016 2015 2017 2016 2015 2017 2016 2015 Segmented product sales $ 9,161 $ 7,209 $ 9,222 $ 784 $ 570 $ 638 $ 632 $ 603 $ 482 Less: royalties (809 ) (524 ) (732 ) (1 ) (1 ) (1 ) (41 ) (26 ) (22 ) Segmented revenue 8,352 6,685 8,490 783 569 637 591 577 460 Segmented expenses Production 2,362 2,186 2,603 400 403 544 226 200 223 Transportation, blending and feedstock 2,291 1,941 2,309 31 48 61 1 2 2 Depletion, depreciation and amortization 3,243 3,465 4,248 509 458 388 205 262 273 Asset retirement obligation accretion 80 66 93 27 35 39 9 12 10 Realized risk management activities (2 ) 8 (843 ) — — — — — — Gain on acquisition, disposition and revaluation of properties (35 ) (32 ) (739 ) — — — — — — (Gain) loss from investments (7 ) (320 ) 6 — — — — — — Total segmented expenses 7,932 7,314 7,677 967 944 1,032 441 476 508 Segmented earnings (loss) before the following $ 420 $ (629 ) $ 813 $ (184 ) $ (375 ) $ (395 ) $ 150 $ 101 $ (48 ) Non–segmented expenses Administration Share-based compensation Interest and other financing expense Unrealized risk management activities Foreign exchange (gain) loss Total non–segmented expenses Earnings (loss) before taxes Current income tax recovery Deferred income tax expense (recovery) Net earnings (loss) 2017 2016 Net (2) expenditures Non-cash and fair value changes (2) (3) Capitalized costs Net expenditures (proceeds) Non-cash and fair value changes (3) Capitalized costs Exploration and evaluation assets Exploration and Production North America (4) $ 160 $ (184 ) $ (24 ) $ 17 $ (211 ) $ (194 ) North Sea — — — — — — Offshore Africa 15 — 15 9 (18 ) (9 ) Oil Sands Mining and Upgrading 142 117 259 — — — $ 317 $ (67 ) $ 250 $ 26 $ (229 ) $ (203 ) Property, plant and equipment Exploration and Production North America $ 2,815 $ 354 $ 3,169 $ 1,143 $ (36 ) $ 1,107 North Sea 160 95 255 126 60 186 Offshore Africa 89 12 101 142 (26 ) 116 3,064 461 3,525 1,411 (2 ) 1,409 Oil Sands Mining and Upgrading (5) 9,592 5,454 15,046 2,718 (23 ) 2,695 Midstream (6) (7) 80 114 194 (315 ) (28 ) (343 ) Head office 19 — 19 17 — 17 $ 12,755 $ 6,029 $ 18,784 $ 3,831 $ (53 ) $ 3,778 (1) This table provides a reconciliation of capitalized costs including derecognitions and does not include the impact of foreign exchange adjustments. (2) Net expenditures on exploration and evaluation assets and property, plant and equipment for the year ended December 31, 2017 exclude non-cash share consideration of $3,818 million issued on the acquisition of AOSP and other assets. This non-cash consideration is included in non-cash and other fair value changes. (3) Asset retirement obligations, transfers of exploration and evaluation assets, transfers of property, plant and equipment to inventory due to change in use, and other fair value adjustments. (4) The above noted figures for 2017 do not include the impact of a pre-tax cash gain of $35 million (2016 - $32 million pre-tax cash gain) on the disposition of exploration and evaluation assets. (5) Net expenditures for Oil Sands Mining and Upgrading include capitalized interest and share-based compensation. (6) The above noted figures for 2016 do not include a pre-tax cash and non-cash gain of $218 million on the disposition of certain Midstream assets to Inter Pipeline. (7) The above noted figures for 2017 include the impact of a pre-tax non-cash revaluation gain of $114 million ( $83 million after-tax) related to a previously held joint interest in a pipeline system. 2017 2016 Exploration and Production North America $ 28,705 $ 28,892 North Sea 1,854 2,269 Offshore Africa 1,331 1,580 Other 29 29 Oil Sands Mining and Upgrading 40,559 24,852 Midstream 1,279 912 Head office 110 114 $ 73,867 $ 58,648

REMUNERATION OF DIRECTORS AND49

REMUNERATION OF DIRECTORS AND SENIOR MANAGEMENT (Tables)	12 Months Ended
	Dec. 31, 2017
Related Party [Abstract]
Remuneration of non-management directors and senior management	Remuneration of Non-Management Directors 2017 2016 2015 Fees earned $ 3 $ 2 $ 2 Remuneration of Senior Management (1) 2017 2016 2015 Salary $ 3 $ 3 $ 3 Common stock option based awards 10 9 7 Annual incentive plans 5 5 2 Long-term incentive plans 17 15 6 $ 35 $ 32 $ 18 (1) Senior management identified above are consistent with the disclosure on Named Executive Officers provided in the Company’s Information Circular to shareholders for the respective years.

ACCOUNTING POLICIES (Details)

ACCOUNTING POLICIES (Details)	12 Months Ended
	Dec. 31, 2017
Bottom of range | Midstream
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful life	5 years
Bottom of range | Other equipment | Oil Sands Mining and Upgrading
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful life	2 years
Top of range | Midstream
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful life	30 years
Top of range | Other equipment | Oil Sands Mining and Upgrading
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful life	18 years
Performance Share Units
Disclosure of detailed information about property, plant and equipment [line items]
Vesting term	3 years

CRITICAL ACCOUNTING ESTIMATES51

CRITICAL ACCOUNTING ESTIMATES AND JUDGEMENTS (Details)	Dec. 31, 2017
Bottom of range
Disclosure of fair value measurement of assets [line items]
Discount Rate Used In Current Measurement Of Higher Of Fair Value Less Costs Of Disposal Or Previous Estimate Of Value In Use	10.00%
Top of range
Disclosure of fair value measurement of assets [line items]
Discount Rate Used In Current Measurement Of Higher Of Fair Value Less Costs Of Disposal Or Previous Estimate Of Value In Use	12.00%

INVENTORY - Schedule of Invento

INVENTORY - Schedule of Inventory (Details) - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Inventories [Abstract]
Product inventory	$ 285	$ 263
Materials and supplies	609	426
Total inventory	$ 894	$ 689

INVENTORY - Narrative (Details)

INVENTORY - Narrative (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Inventories [Abstract]
Write-down of product inventory	$ 33	$ 73

EXPLORATION AND EVALUATION AS54

EXPLORATION AND EVALUATION ASSETS - Detailed information about exploration and evaluation assets (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Detailed Information About Exploration For And Evaluation Of Mineral Resources [Line Items]
Beginning balance	$ 2,382	$ 2,586
Additions	159	29
Acquisition of AOSP and other assets (note 7)	290
Transfers to property, plant and equipment	(198)	(211)
Disposals/derecognitions	(1)	(21)
Foreign exchange adjustments		(1)
Ending balance	2,632	2,382
North America
Disclosure Of Detailed Information About Exploration For And Evaluation Of Mineral Resources [Line Items]
Beginning balance	2,306	2,500
Additions	144	20
Acquisition of AOSP and other assets (note 7)	31
Transfers to property, plant and equipment	(198)	(211)
Disposals/derecognitions	(1)	(3)
Foreign exchange adjustments		0
Ending balance	2,282	2,306
North Sea
Disclosure Of Detailed Information About Exploration For And Evaluation Of Mineral Resources [Line Items]
Beginning balance	0	0
Additions	0	0
Acquisition of AOSP and other assets (note 7)	0
Transfers to property, plant and equipment	0	0
Disposals/derecognitions	0	0
Foreign exchange adjustments		0
Ending balance	0	0
Offshore Africa
Disclosure Of Detailed Information About Exploration For And Evaluation Of Mineral Resources [Line Items]
Beginning balance	76	86
Additions	15	9
Acquisition of AOSP and other assets (note 7)	0
Transfers to property, plant and equipment	0	0
Disposals/derecognitions	0	(18)
Foreign exchange adjustments		(1)
Ending balance	91	76
Oil Sands Mining and Upgrading
Disclosure Of Detailed Information About Exploration For And Evaluation Of Mineral Resources [Line Items]
Beginning balance	0	0
Additions	0	0
Acquisition of AOSP and other assets (note 7)	259
Transfers to property, plant and equipment	0	0
Disposals/derecognitions	0	0
Foreign exchange adjustments		0
Ending balance	$ 259	$ 0

EXPLORATION AND EVALUATION AS55

EXPLORATION AND EVALUATION ASSETS - Narrative (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Detailed Information About Exploration For And Evaluation Of Mineral Resources [Line Items]
Acquisition of exploration and evaluation assets	$ 290
Disposals of exploration and evaluation assets	1	$ 21
Proceeds from disposal of exploration and evaluation assets	35	35	$ 416
North America
Disclosure Of Detailed Information About Exploration For And Evaluation Of Mineral Resources [Line Items]
Acquisition of exploration and evaluation assets	31
Disposals of exploration and evaluation assets	1	3
Proceeds from disposal of exploration and evaluation assets	36	35
Gain on sale of exploration and evaluation assets	35	32
Offshore Africa
Disclosure Of Detailed Information About Exploration For And Evaluation Of Mineral Resources [Line Items]
Acquisition of exploration and evaluation assets	0
Disposals of exploration and evaluation assets	$ 0	$ 18

PROPERTY, PLANT AND EQUIPMENT -

PROPERTY, PLANT AND EQUIPMENT - Detailed information about property, plant and equipment (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	$ 50,910
Ending Balance	65,170	$ 50,910
Project costs not subject to depletion and depreciation	944	846
Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	101,826	98,425
Additions	5,232	4,609
Transfers from E&E assets	198	211
Disposals/derecognitions	(827)	(1,042)
Foreign exchange adjustments and other	(861)	(377)
Ending Balance	119,749	101,826
Accumulated depletion and depreciation
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	(50,916)	(46,950)
Expense	(5,186)	(4,840)
Disposals/derecognitions	827	641
Foreign exchange adjustments and other	696	233
Ending Balance	(54,579)	(50,916)
Operating segments | North America
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	23,336
Ending Balance	23,665	23,336
Operating segments | North America | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	61,647	60,540
Additions	3,003	1,462
Transfers from E&E assets	198	211
Disposals/derecognitions	(381)	(566)
Foreign exchange adjustments and other	0	0
Ending Balance	64,816	61,647
Operating segments | North America | Accumulated depletion and depreciation
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	(38,311)	(35,347)
Expense	(3,220)	(3,440)
Disposals/derecognitions	381	486
Foreign exchange adjustments and other	(1)	(10)
Ending Balance	(41,151)	(38,311)
Operating segments | North Sea
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	1,796
Ending Balance	1,473	1,796
Operating segments | North Sea | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	7,380	7,414
Additions	255	186
Transfers from E&E assets	0	0
Disposals/derecognitions	0	0
Foreign exchange adjustments and other	(509)	(220)
Ending Balance	7,126	7,380
Operating segments | North Sea | Accumulated depletion and depreciation
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	(5,584)	(5,264)
Expense	(509)	(457)
Disposals/derecognitions	0	0
Foreign exchange adjustments and other	440	137
Ending Balance	(5,653)	(5,584)
Operating segments | Offshore Africa
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	1,335
Ending Balance	1,162	1,335
Operating segments | Offshore Africa | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	5,132	5,173
Additions	101	116
Transfers from E&E assets	0	0
Disposals/derecognitions	0	0
Foreign exchange adjustments and other	(352)	(157)
Ending Balance	4,881	5,132
Operating segments | Offshore Africa | Accumulated depletion and depreciation
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	(3,797)	(3,659)
Expense	(205)	(243)
Disposals/derecognitions	0	0
Foreign exchange adjustments and other	283	105
Ending Balance	(3,719)	(3,797)
Operating segments | Oil Sands Mining and Upgrading
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	24,210
Ending Balance	38,456	24,210
Operating segments | Oil Sands Mining and Upgrading | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	27,038	24,343
Additions	1,660	2,822
Transfers from E&E assets	0	0
Disposals/derecognitions	(446)	(127)
Foreign exchange adjustments and other	0	0
Ending Balance	42,084	27,038
Operating segments | Oil Sands Mining and Upgrading | Accumulated depletion and depreciation
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	(2,828)	(2,294)
Expense	(1,220)	(662)
Disposals/derecognitions	446	127
Foreign exchange adjustments and other	(26)	1
Ending Balance	(3,628)	(2,828)
Operating segments | Midstream
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	119
Ending Balance	304	119
Operating segments | Midstream | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	234	577
Additions	194	6
Transfers from E&E assets	0	0
Disposals/derecognitions	0	(349)
Foreign exchange adjustments and other	0	0
Ending Balance	428	234
Operating segments | Midstream | Accumulated depletion and depreciation
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	(115)	(132)
Expense	(9)	(11)
Disposals/derecognitions	0	28
Foreign exchange adjustments and other	0	0
Ending Balance	(124)	(115)
Head office
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	114
Ending Balance	110	114
Head office | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	395	378
Additions	19	17
Transfers from E&E assets	0	0
Disposals/derecognitions	0	0
Foreign exchange adjustments and other	0	0
Ending Balance	414	395
Head office | Accumulated depletion and depreciation
Reconciliation of changes in property, plant and equipment [abstract]
Beginning Balance	(281)	(254)
Expense	(23)	(27)
Disposals/derecognitions	0	0
Foreign exchange adjustments and other	0	0
Ending Balance	(304)	$ (281)
AOSP | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Acquisition of AOSP and other assets (note 7)	14,181
AOSP | Operating segments | North America | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Acquisition of AOSP and other assets (note 7)	349
AOSP | Operating segments | North Sea | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Acquisition of AOSP and other assets (note 7)	0
AOSP | Operating segments | Offshore Africa | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Acquisition of AOSP and other assets (note 7)	0
AOSP | Operating segments | Oil Sands Mining and Upgrading | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Acquisition of AOSP and other assets (note 7)	13,832
AOSP | Operating segments | Midstream | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Acquisition of AOSP and other assets (note 7)	0
AOSP | Head office | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Acquisition of AOSP and other assets (note 7)	$ 0

PROPERTY, PLANT AND EQUIPMENT57

PROPERTY, PLANT AND EQUIPMENT - Narrative (Details) - CAD ($) $ / shares in Units, shares in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 31, 2017
Disclosure of detailed information about property, plant and equipment [line items]
Interest costs capitalized	$ 82,000,000	$ 233,000,000	$ 244,000,000
Weighted average capitalization rate	3.80%	3.90%	3.90%
North America, Exploration and Production segment and Midstream segment
Disclosure of detailed information about property, plant and equipment [line items]
Net cash consideration for acquisition of exploration and evaluation assets	$ 1,013,000,000	$ 159,000,000	$ 406,000,000
Asset retirement obligations	63,000,000	30,000,000	133,000,000
Deferred tax liabilities	0	0	0
North America
Disclosure of detailed information about property, plant and equipment [line items]
Acquired exploration and evaluation assets	27,000,000	0	$ 37,000,000
Midstream
Disclosure of detailed information about property, plant and equipment [line items]
Revaluation pre-tax gain	114,000,000
Revaluation after-tax gain	$ 83,000,000
Pre-tax and after-tax gain on disposal of property, plant and equipment		218,000,000
AOSP
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment				$ 14,181,000,000
Asset retirement obligations				721,000,000
Deferred tax liabilities				1,287,000,000
AOSP | Oil Sands Mining and Upgrading segment and North America Exploration and Production segment
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment				$ 14,181,000,000
Disposal of Cold Lake Pipeline
Disclosure of detailed information about property, plant and equipment [line items]
Net proceeds on sale of property, plant and equipment		349,000,000
Disposal of Cold Lake Pipeline | Inter Pipeline
Disclosure of detailed information about property, plant and equipment [line items]
Non-cash share consideration received		$ 190,000,000
Non-cash share consideration received (in shares)		6.4
Non-cash share consideration received, price per share (in CAD per share)		$ 29.57
Disposal of Cold Lake Pipeline | Midstream
Disclosure of detailed information about property, plant and equipment [line items]
Disposals of property, plant and equipment		$ 321,000,000
Net consideration received, property, plant and equipment		539,000,000
Pre-tax and after-tax gain on disposal of property, plant and equipment		$ 218,000,000

ACQUISITION OF INTERESTS IN T58

ACQUISITION OF INTERESTS IN THE ATHABASCA OIL SANDS PROJECT AND OTHER ASSETS - Narrative (Details) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017CAD ($)	Dec. 31, 2016CAD ($)	Dec. 31, 2015CAD ($)	May 31, 2017USD ($)shares	May 31, 2017CAD ($)shares
Disclosure of detailed information about business combination [line items]
Borrowings	$ 22,458,000,000	$ 16,805,000,000
Revenue	16,651,000,000	$ 10,523,000,000	$ 12,363,000,000
Non-revolving term credit facility maturing May 2020
Disclosure of detailed information about business combination [line items]
Borrowings	3,000,000,000
Non-revolving term loan facility	3,000,000,000
AOSP
Disclosure of detailed information about business combination [line items]
Interest acquired				70.00%	70.00%
Total purchase consideration					$ 12,541,000,000
Cash transferred					$ 8,217,000,000
Common shares issued (in shares) | shares				97.6	97.6
Fair value of share considerations issued	3,818,000,000				$ 3,818,000,000
Deferred purchase consideration payable				$ 375	506,000,000
Gain on acquisition, net of transaction costs	230,000,000
Acquisition related transaction costs	3,000,000
Revenue attributable to acquisition	2,872,000,000
Revenue	16,651,000,000
Net operating income attributable to acquisition	1,166,000,000
Net operating income	8,138,000,000
Pro forma revenue attributable to acquiree	2,181,000,000
Pro forma revenue as if combination occurred at beginning of period	18,832,000,000
Pro forma net operating income attributable to acquiree	735,000,000
Pro forma net operating income as if combination occurred at beginning of period	$ 8,873,000,000
AOSP | Medium-term notes
Disclosure of detailed information about business combination [line items]
Borrowings					1,800,000,000
AOSP | Long-term debt
Disclosure of detailed information about business combination [line items]
Borrowings				$ 3,000
AOSP | Non-revolving term credit facility maturing May 2020
Disclosure of detailed information about business combination [line items]
Non-revolving term loan facility					$ 3,000,000,000
AOSP, Mining And Extraction Operations
Disclosure of detailed information about business combination [line items]
Interest acquired				70.00%	70.00%
AOSP, Scotford Upgrader And Quest Carbon Capture And Storage Project
Disclosure of detailed information about business combination [line items]
Interest acquired				70.00%	70.00%
AOSP, Peace River Thermal In Situ Operations And Cliffdale Heavy Oil Field
Disclosure of detailed information about business combination [line items]
Interest acquired				100.00%	100.00%

ACQUISITION OF INTERESTS IN T59

ACQUISITION OF INTERESTS IN THE ATHABASCA OIL SANDS PROJECT AND OTHER ASSETS - Summary of Net Assets Acquired and Liabilities Assumed (Details) - AOSP - CAD ($) $ in Millions	May 31, 2017	Dec. 31, 2017
Disclosure of detailed information about business combination [line items]
Cash	$ 93
Other working capital	291	$ 291
Property, plant and equipment	14,181
Exploration and evaluation assets	290
Asset retirement obligations	(721)
Other long-term liabilities	(73)
Deferred income taxes	(1,287)
Net assets acquired	12,774
Total purchase consideration	12,541
Gain on acquisition before transaction costs	$ 233

INVESTMENTS - Summary of Invest

INVESTMENTS - Summary of Investments (Details) - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about financial instruments [line items]
Investments	$ 893	$ 913
Investment in PrairieSky Royalty Ltd.
Disclosure of detailed information about financial instruments [line items]
Investments	726	723
Investment in Inter Pipeline Ltd.
Disclosure of detailed information about financial instruments [line items]
Investments	$ 167	$ 190

INVESTMENTS - Narrative (Detail

INVESTMENTS - Narrative (Details) - CAD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
Investment in PrairieSky Royalty Ltd.
Disclosure of detailed information about financial instruments [line items]
Non-cash share consideration received		$ 985
Non-cash share consideration received (in shares)		44.4
Non-cash share consideration received, price per share (in CAD per share)		$ 22.16
Ownership interest in investment (less than)			10.00%
Number of shares held as investment (in shares)			22.6
Investment in Inter Pipeline Ltd.
Disclosure of detailed information about financial instruments [line items]
Number of shares held as investment (in shares)			6.4
Partial disposal of PrairieSky Royalty Ltd.
Disclosure of detailed information about financial instruments [line items]
Non-cash shares distributed (in shares)	21.8
Return of capital on PrairieSky Royalty Ltd. share distribution	$ 546
Disposal of Cold Lake Pipeline | Investment in Inter Pipeline Ltd.
Disclosure of detailed information about financial instruments [line items]
Non-cash share consideration received	$ 190
Non-cash share consideration received (in shares)	6.4
Non-cash share consideration received, price per share (in CAD per share)	$ 29.57

INVESTMENTS - PrairieSky (Detai

INVESTMENTS - PrairieSky (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about financial instruments [line items]
(Gain) loss from investment	$ (38)	$ (327)	$ 50
Investment in PrairieSky Royalty Ltd.
Disclosure of detailed information about financial instruments [line items]
(Gain) loss from investments	(3)	(292)	11
Dividend income	(17)	(27)	(5)
(Gain) loss from investment	$ (20)	$ (319)	$ 6

INVESTMENTS - Inter Pipeline (D

INVESTMENTS - Inter Pipeline (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of financial assets [line items]
(Gain) loss from investment	$ (38)	$ (327)	$ 50
Investment in Inter Pipeline Ltd.
Disclosure of financial assets [line items]
(Gain) loss from investments	23	0	0
Dividend income	(10)	(1)	0
(Gain) loss from investment	$ 13	$ (1)	$ 0

OTHER LONG-TERM ASSETS - Schedu

OTHER LONG-TERM ASSETS - Schedule of other long-term assets (Details) - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Subclassifications of assets, liabilities and equities [abstract]
Investment in North West Redwater Partnership	$ 292	$ 261
North West Redwater Partnership subordinated debt	510	385
Risk Management (note 18)	204	489
Other	241	168
Other assets	1,247	1,303
Current portion of other long-term assets	79	283
Other long-term assets	$ 1,168	$ 1,020

OTHER LONG-TERM ASSETS - Narrat

OTHER LONG-TERM ASSETS - Narrative (Details)	12 Months Ended
	Dec. 31, 2017CAD ($)bbl	Dec. 31, 2013	Mar. 21, 2018CAD ($)	Dec. 31, 2016CAD ($)
Disclosure of joint ventures [line items]
North West Redwater Partnership subordinated debt	$ 510,000,000			$ 385,000,000
Borrowings	$ 22,458,000,000			16,805,000,000
North West Redwater Partnership
Disclosure of joint ventures [line items]
Company's voting percent interest in joint venture	50.00%
Processing agreement, barrels of bitumen feedstock per day | bbl	50,000
Processing agreement, barrels of bitumen feedstock per date for the Company | bbl	12,500
Processing agreement, barrels of bitumen feedstock per date for others | bbl	37,500
Company's ownership interest in joint venture	50.00%	50.00%
Subordinated debt interest rate variable		6.00%
Subordinated debt contributed before accrued interest	$ 411,000,000
Accrued interest	99,000,000
North West Redwater Partnership subordinated debt	$ 510,000,000
Percent of pro rata share of debt company has committed paying to joint venture	25.00%
Term of commitment to joint venture	30 years
North West Redwater Partnership
Disclosure of joint ventures [line items]
Processing agreement, barrels of bitumen feedstock per day | bbl	50,000
Processing agreement term	30 years
Facility capital cost budget for the Project	$ 9,500,000,000
Possible percentage increase in the facility capital cost budget	2.00%
North West Redwater Partnership | 2.80% Series J Senior Secured Bonds Due June 2027
Disclosure of joint ventures [line items]
Bonds issued	$ 750,000,000
Bonds issued, interest rate	2.80%
North West Redwater Partnership | 3.65% Series K Senior Secured Bonds Due June 2035
Disclosure of joint ventures [line items]
Bonds issued	$ 750,000,000
Bonds issued, interest rate	3.65%
North West Redwater Partnership | 4.25% Series F Senior Secured Bonds Due June 2029
Disclosure of joint ventures [line items]
Bonds issued				$ 550,000,000
Bonds issued, interest rate				4.25%
North West Redwater Partnership | 4.75% Percent Series G Senior Secured Bonds Due June 2037
Disclosure of joint ventures [line items]
Bonds issued				$ 500,000,000
Bonds issued, interest rate				4.75%
North West Redwater Partnership | 4.15% Series H Senior Secured Bonds Due June 2033
Disclosure of joint ventures [line items]
Bonds issued				$ 500,000,000
Bonds issued, interest rate				4.15%
North West Redwater Partnership | 4.35% Series I Senior Secured Bonds Due January 2039
Disclosure of joint ventures [line items]
Bonds issued				$ 500,000,000
Bonds issued, interest rate				4.35%
North West Redwater Partnership | Syndicated credit facility
Disclosure of joint ventures [line items]
Borrowings	$ 1,870,000,000
Maximum credit facility	$ 3,500,000,000
Major debt transactions | North West Redwater Partnership | Syndicated credit facility
Disclosure of joint ventures [line items]
Maximum credit facility			$ 2,000,000,000
Major debt transactions | North West Redwater Partnership | Non-Revolving Term Credit Facility Maturing February 2020
Disclosure of joint ventures [line items]
Maximum credit facility			$ 1,500,000,000

OTHER LONG-TERM ASSETS - Summar

OTHER LONG-TERM ASSETS - Summary of Assets, Liabilities, Partners' Equity and Equity (Income) Loss (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of joint ventures [line items]
Current assets	$ 4,897	$ 4,336
Current liabilities	6,261	5,092
Equity	31,653	26,267	$ 27,381
Equity income	(2,397)	204	$ 637
North West Redwater Partnership
Disclosure of joint ventures [line items]
Current assets	165	48
Non-current assets	5,270	4,129
Current liabilities	1,238	286
Non-current liabilities	3,905	3,630
Equity	292	261
Equity income	(31)	(7)
North West Redwater Partnership
Disclosure of joint ventures [line items]
Current assets	330	96
Non-current assets	10,540	8,258
Current liabilities	2,476	572
Non-current liabilities	7,810	7,260
Equity	584	522
Equity income	$ (62)	$ (14)

LONG-TERM DEBT - Summary of Lon

LONG-TERM DEBT - Summary of Long-term Debt (Details)	Dec. 31, 2017USD ($)	Dec. 31, 2017CAD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2016CAD ($)
Disclosure of detailed information about borrowings [line items]
Borrowings		$ 22,458,000,000		$ 16,805,000,000
Less: current portion of commercial paper		625,000,000		336,000,000
Current portion of other long-term debt		1,252,000,000		1,476,000,000
Long-term debt		$ 20,581,000,000		14,993,000,000
3.05% debentures due June 19, 2019
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate	3.05%	3.05%
2.60% debentures due December 3, 2019
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate	2.60%	2.60%
2.05% debentures due June 1, 2020
Disclosure of detailed information about borrowings [line items]
Notional amount		$ 900,000,000
Borrowings, interest rate	2.05%	2.05%
2.89% debentures due August 14, 2020
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate	2.89%	2.89%
3.31% debentures due February 11, 2022
Disclosure of detailed information about borrowings [line items]
Notional amount		$ 1,000,000,000
Borrowings, interest rate	3.31%	3.31%
3.55% debentures due June 3, 2024
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate	3.55%	3.55%
3.42% debentures due December 1, 2026
Disclosure of detailed information about borrowings [line items]
Notional amount		$ 600,000,000
Borrowings, interest rate	3.42%	3.42%
4.85% debentures due May 30, 2047
Disclosure of detailed information about borrowings [line items]
Notional amount		$ 300,000,000
Borrowings, interest rate	4.85%	4.85%
Bank credit facilities (December 31, 2017 - US$1,839 million; December 31, 2016 - US$905 million)
Disclosure of detailed information about borrowings [line items]
Borrowings	$ 1,839,000,000		$ 905,000,000
Commercial paper (December 31, 2017 - US$500 million; December 31, 2016 - US$250 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	500,000,000		$ 250,000,000
5.70% due May 15, 2017 (US$1,100 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 1,100,000,000
Borrowings, interest rate	5.70%	5.70%
1.75% due January 15, 2018 (US$600 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 600,000,000
Borrowings, interest rate	1.75%	1.75%
5.90% due February 1, 2018 (US$400 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 400,000,000
Borrowings, interest rate	5.90%	5.90%
3.45% due November 15, 2021 (US$500 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 500,000,000
Borrowings, interest rate	3.45%	3.45%
2.95% due January 15, 2023 (US$1,000 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 1,000,000,000
Borrowings, interest rate	2.95%	2.95%
3.80% due April 15, 2024 (US$500 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 500,000,000
Borrowings, interest rate	3.80%	3.80%
3.90% due February 1, 2025 (US$600 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 600,000,000
Borrowings, interest rate	3.90%	3.90%
3.85% due June 1, 2027 (US$1,250 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 1,250,000,000
Borrowings, interest rate	3.85%	3.85%
7.20% due January 15, 2032 (US$400 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 400,000,000
Borrowings, interest rate	7.20%	7.20%
6.45% due June 30, 2033 (US$350 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 350,000,000
Borrowings, interest rate	6.45%	6.45%
5.85% due February 1, 2035 (US$350 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 350,000,000
Borrowings, interest rate	5.85%	5.85%
6.50% due February 15, 2037 (US$450 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 450,000,000
Borrowings, interest rate	6.50%	6.50%
6.25% due March 15, 2038 (US$1,100 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 1,100,000,000
Borrowings, interest rate	6.25%	6.25%
6.75% due February 1, 2039 (US$400 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 400,000,000
Borrowings, interest rate	6.75%	6.75%
4.95% due June 1, 2047 (US$750 million)
Disclosure of detailed information about borrowings [line items]
Notional amount	$ 750,000,000
Borrowings, interest rate	4.95%	4.95%
Gross carrying amount
Disclosure of detailed information about borrowings [line items]
Borrowings		$ 22,597,000,000		16,870,000,000
Gross carrying amount | Bank credit facilities
Disclosure of detailed information about borrowings [line items]
Borrowings		3,544,000,000		2,758,000,000
Gross carrying amount | 3.05% debentures due June 19, 2019
Disclosure of detailed information about borrowings [line items]
Borrowings		500,000,000		500,000,000
Gross carrying amount | 2.60% debentures due December 3, 2019
Disclosure of detailed information about borrowings [line items]
Borrowings		500,000,000		500,000,000
Gross carrying amount | 2.05% debentures due June 1, 2020
Disclosure of detailed information about borrowings [line items]
Borrowings		900,000,000		0
Gross carrying amount | 2.89% debentures due August 14, 2020
Disclosure of detailed information about borrowings [line items]
Borrowings		1,000,000,000		1,000,000,000
Gross carrying amount | 3.31% debentures due February 11, 2022
Disclosure of detailed information about borrowings [line items]
Borrowings		1,000,000,000		1,000,000,000
Gross carrying amount | 3.55% debentures due June 3, 2024
Disclosure of detailed information about borrowings [line items]
Borrowings		500,000,000		500,000,000
Gross carrying amount | 3.42% debentures due December 1, 2026
Disclosure of detailed information about borrowings [line items]
Borrowings		600,000,000		0
Gross carrying amount | 4.85% debentures due May 30, 2047
Disclosure of detailed information about borrowings [line items]
Borrowings		300,000,000		0
Gross carrying amount | Medium-term notes
Disclosure of detailed information about borrowings [line items]
Borrowings		8,844,000,000		6,258,000,000
Gross carrying amount | Bank credit facilities (December 31, 2017 - US$1,839 million; December 31, 2016 - US$905 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		2,300,000,000		1,213,000,000
Gross carrying amount | Commercial paper (December 31, 2017 - US$500 million; December 31, 2016 - US$250 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		625,000,000		336,000,000
Gross carrying amount | 5.70% due May 15, 2017 (US$1,100 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		0		1,477,000,000
Gross carrying amount | 1.75% due January 15, 2018 (US$600 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		751,000,000		806,000,000
Gross carrying amount | 5.90% due February 1, 2018 (US$400 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		501,000,000		537,000,000
Gross carrying amount | 3.45% due November 15, 2021 (US$500 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		625,000,000		671,000,000
Gross carrying amount | 2.95% due January 15, 2023 (US$1,000 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		1,252,000,000		0
Gross carrying amount | 3.80% due April 15, 2024 (US$500 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		625,000,000		671,000,000
Gross carrying amount | 3.90% due February 1, 2025 (US$600 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		751,000,000		806,000,000
Gross carrying amount | 3.85% due June 1, 2027 (US$1,250 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		1,566,000,000		0
Gross carrying amount | 7.20% due January 15, 2032 (US$400 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		501,000,000		537,000,000
Gross carrying amount | 6.45% due June 30, 2033 (US$350 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		438,000,000		470,000,000
Gross carrying amount | 5.85% due February 1, 2035 (US$350 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		438,000,000		470,000,000
Gross carrying amount | 6.50% due February 15, 2037 (US$450 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		563,000,000		604,000,000
Gross carrying amount | 6.25% due March 15, 2038 (US$1,100 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		1,377,000,000		1,477,000,000
Gross carrying amount | 6.75% due February 1, 2039 (US$400 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		501,000,000		537,000,000
Gross carrying amount | 4.95% due June 1, 2047 (US$750 million)
Disclosure of detailed information about borrowings [line items]
Borrowings		939,000,000		0
Gross carrying amount | Long-term debt
Disclosure of detailed information about borrowings [line items]
Borrowings		13,753,000,000		10,612,000,000
Original issue discounts, net
Disclosure of detailed information about borrowings [line items]
Borrowings		18,000,000		10,000,000
Transaction costs
Disclosure of detailed information about borrowings [line items]
Borrowings		$ 121,000,000		$ 55,000,000

LONG-TERM DEBT - Narrative (Det

LONG-TERM DEBT - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 21, 2018USD ($)	Mar. 21, 2018CAD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2017CAD ($)	Dec. 31, 2017EUR (€)	May 31, 2017USD ($)	May 31, 2017CAD ($)	Dec. 31, 2016CAD ($)
Disclosure of detailed information about borrowings [line items]
Borrowings					$ 22,458,000,000				$ 16,805,000,000
Letters of credit and guarantees outstanding					866,000,000
Financial guarantees outstanding					39,000,000
Bank credit facilities
Disclosure of detailed information about borrowings [line items]
Maximum credit facility					11,050,000,000
Undrawn borrowing facilities					4,112,000,000
Demand credit facility
Disclosure of detailed information about borrowings [line items]
Maximum credit facility					100,000,000	€ 15,000,000
Non-revolving term credit facility maturing February 2019
Disclosure of detailed information about borrowings [line items]
Maximum credit facility					750,000,000
125 million non-revolving term credit facility maturing February 2019
Disclosure of detailed information about borrowings [line items]
Maximum credit facility					125,000,000
Non-revolving term credit facility maturing October 2019
Disclosure of detailed information about borrowings [line items]
Maximum credit facility					2,200,000,000				$ 1,500,000,000
Borrowings					2,200,000,000
Non-revolving term credit facility maturing May 2020
Disclosure of detailed information about borrowings [line items]
Maximum credit facility					3,000,000,000
Borrowings					$ 3,000,000,000
Amortisation rate			5.00%		5.00%	5.00%
Letter of credit
Disclosure of detailed information about borrowings [line items]
Maximum credit facility			$ 375,000,000
Revolving syndicated credit facility maturing June 2020
Disclosure of detailed information about borrowings [line items]
Maximum credit facility					$ 2,425,000,000
Revolving syndicated credit facility
Disclosure of detailed information about borrowings [line items]
Maximum credit facility					2,425,000,000
Revolving syndicated credit facility maturing June 2019
Disclosure of detailed information about borrowings [line items]
Maximum credit facility					330,000,000
Undrawn borrowing facilities					330,000,000
Revolving syndicated credit facility maturing June 2021
Disclosure of detailed information about borrowings [line items]
Maximum credit facility					$ 2,095,000,000
Commercial paper (December 31, 2017 - US$500 million; December 31, 2016 - US$250 million)
Disclosure of detailed information about borrowings [line items]
Maximum credit facility			2,500,000,000
Notional amount			$ 500,000,000	$ 250,000,000
Credit facilities and commercial paper | Weighted average
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate			2.20%	1.90%	2.20%	2.20%			1.90%
Long-term debt | Weighted average
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate			3.80%	3.90%	3.80%	3.80%			3.90%
2.05% debentures due June 1, 2020
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate			2.05%		2.05%	2.05%
Notional amount					$ 900,000,000
3.42% debentures due December 1, 2026
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate			3.42%		3.42%	3.42%
Notional amount					$ 600,000,000
4.85% debentures due May 30, 2047
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate			4.85%		4.85%	4.85%
Notional amount					$ 300,000,000
Medium-Term Borrowings Expiring August 2019 [Member]
Disclosure of detailed information about borrowings [line items]
Base shell prospectus borrowings					$ 3,000,000,000
3.31% debentures due February 11, 2022
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate			3.31%		3.31%	3.31%
Notional amount					$ 1,000,000,000
5.70% due May 15, 2017 (US$1,100 million)
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate			5.70%		5.70%	5.70%
Notional amount			$ 1,100,000,000
Repayment of borrowings			$ 1,100,000,000
2.95% due January 15, 2023 (US$1,000 million)
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate			2.95%		2.95%	2.95%
Notional amount			$ 1,000,000,000
3.85% due June 1, 2027 (US$1,250 million)
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate			3.85%		3.85%	3.85%
Notional amount			$ 1,250,000,000
4.95% due June 1, 2047 (US$750 million)
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate			4.95%		4.95%	4.95%
Notional amount			$ 750,000,000
US dollar denominated debt, unsecured
Disclosure of detailed information about borrowings [line items]
Base shell prospectus borrowings			$ 3,000,000,000
Three-month LIBOR plus 0.375%
Disclosure of detailed information about borrowings [line items]
Repayment of borrowings				$ 500,000,000
Three-month LIBOR plus 0.375% | LIBOR
Disclosure of detailed information about borrowings [line items]
Interest rate				0.375%					0.375%
6% Notes
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate				6.00%					6.00%
Repayment of borrowings				$ 250,000,000
1.75% due January 15, 2018 (US$600 million)
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate			1.75%		1.75%	1.75%
Notional amount			$ 600,000,000
5.90% due February 1, 2018 (US$400 million)
Disclosure of detailed information about borrowings [line items]
Borrowings, interest rate			5.90%		5.90%	5.90%
Notional amount			$ 400,000,000
North Sea
Disclosure of detailed information about borrowings [line items]
Letters of credit outstanding					$ 63,000,000
AOSP
Disclosure of detailed information about borrowings [line items]
Letters of credit outstanding					$ 651,000,000
AOSP | Non-revolving term credit facility maturing May 2020
Disclosure of detailed information about borrowings [line items]
Maximum credit facility								$ 3,000,000,000
AOSP | Long-term debt
Disclosure of detailed information about borrowings [line items]
Borrowings							$ 3,000,000,000
AOSP | Medium-term notes
Disclosure of detailed information about borrowings [line items]
Borrowings								$ 1,800,000,000
Major debt transactions | 125 million non-revolving term credit facility maturing February 2019
Disclosure of detailed information about borrowings [line items]
Repayment of borrowings		$ 125,000,000
Major debt transactions | Non-revolving term credit facility maturing February 2021
Disclosure of detailed information about borrowings [line items]
Maximum credit facility		750,000,000
Major debt transactions | Non-revolving term credit facility maturing May 2020
Disclosure of detailed information about borrowings [line items]
Borrowings		2,850,000,000
Repayment of borrowings		$ 150,000,000
Major debt transactions | 1.75% due January 15, 2018 (US$600 million)
Disclosure of detailed information about borrowings [line items]
Repayment of borrowings	$ 600,000,000
Major debt transactions | 5.90% due February 1, 2018 (US$400 million)
Disclosure of detailed information about borrowings [line items]
Repayment of borrowings	$ 400,000,000

LONG-TERM DEBT - Schedule of De

LONG-TERM DEBT - Schedule of Debt Repayments (Details) - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Borrowings	$ 22,458	$ 16,805
Gross carrying amount
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Borrowings	22,597	$ 16,870
Gross carrying amount | 2018
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Borrowings	2,027
Gross carrying amount | 2019
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Borrowings	4,228
Gross carrying amount | 2020
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Borrowings	4,231
Gross carrying amount | 2021
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Borrowings	760
Gross carrying amount | 2022
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Borrowings	1,000
Gross carrying amount | Thereafter
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Borrowings	$ 10,351

OTHER LONG-TERM LIABILITIES - S

OTHER LONG-TERM LIABILITIES - Schedule of other long-term liabilities (Details) $ in Millions, $ in Millions	Dec. 31, 2017USD ($)	Dec. 31, 2017CAD ($)	Dec. 31, 2016CAD ($)	Dec. 31, 2015CAD ($)	Dec. 31, 2014CAD ($)
Disclosure Of Other Non-Current Liabilities [Line Items]
Asset retirement obligations		$ 4,327	$ 3,243	$ 2,950	$ 4,221
Share-based compensation		414	426	$ 128	$ 203
Risk management (note 18)		103	0
Other		565	17
Other liabilities		5,409	3,686
Current portion of other long-term liabilities		1,012	463
Other long-term liabilities		4,397	$ 3,223
AOSP
Disclosure Of Other Non-Current Liabilities [Line Items]
Deferred purchase consideration payable	$ 375	$ 469

OTHER LONG-TERM LIABILITIES - A

OTHER LONG-TERM LIABILITIES - Asset Retirement Obligations (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of other provisions [line items]
Asset retirement obligations settlement period	60 years
Reconciliation Of Changes In Provision For Decommissioning Restoration And Rehabilitation Costs [Roll Forward]
Balance – beginning of year	$ 3,243	$ 2,950	$ 4,221
Balance – end of year	4,327	3,243	2,950
Less: current portion	92	95	101
Non-current asset retirement obligation	$ 4,235	$ 3,148	$ 2,849
Provision for decommissioning, restoration and rehabilitation costs [member]
Disclosure of other provisions [line items]
Weighted average discount rate	4.70%	5.20%	5.90%
Reconciliation Of Changes In Provision For Decommissioning Restoration And Rehabilitation Costs [Roll Forward]
Liabilities incurred	$ 12	$ 3	$ 7
Liabilities acquired, net	784	30	129
Liabilities settled	(274)	(267)	(370)
Asset retirement obligation accretion	164	142	173
Revision of cost, inflation rates and timing estimates	(40)	(68)	(313)
Change in discount rate	509	493	(1,150)
Foreign exchange adjustments	$ (71)	$ (40)	$ 253

OTHER LONG-TERM LIABILITIES -72

OTHER LONG-TERM LIABILITIES - Segmented Asset Retirement Obligations (Details) - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of operating segments [line items]
Asset retirement obligations	$ 4,327	$ 3,243	$ 2,950	$ 4,221
North America
Disclosure of operating segments [line items]
Asset retirement obligations	1,840	1,444
North Sea
Disclosure of operating segments [line items]
Asset retirement obligations	755	837
Offshore Africa
Disclosure of operating segments [line items]
Asset retirement obligations	245	244
Oil Sands Mining and Upgrading
Disclosure of operating segments [line items]
Asset retirement obligations	1,486	717
Midstream
Disclosure of operating segments [line items]
Asset retirement obligations	$ 1	$ 1

OTHER LONG-TERM LIABILITIES -73

OTHER LONG-TERM LIABILITIES - Share-Based Compensation (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation Of Changes In Liabilities From Share-Based Payment Transactions [Roll Forward]
Balance – beginning of year	$ 426	$ 128	$ 203
Share-based compensation expense (recovery)	134	355	(46)
Cash payment for stock options surrendered	(6)	(7)	(1)
Transferred to common shares	(154)	(117)	(18)
Charged to (recovered from) Oil Sands Mining and Upgrading, net	14	67	(10)
Balance – end of year	414	426	128
Less: current portion	348	368	105
Non-current liabilities from share-based payment arrangements	66	58	23
Performance Share Units
Reconciliation Of Changes In Liabilities From Share-Based Payment Transactions [Roll Forward]
Share-based compensation expense (recovery)	$ 5	$ 0	$ 0

OTHER LONG-TERM LIABILITIES - W

OTHER LONG-TERM LIABILITIES - Weighted Average Assumptions Used to Calculate Share-Based Compensation Liability (Details)	12 Months Ended
	Dec. 31, 2017CAD ($)year	Dec. 31, 2016CAD ($)year	Dec. 31, 2015CAD ($)year
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value	$ 11.82	$ 11.41	$ 3.06
Share price	$ 44.92	$ 42.79	$ 30.22
Expected volatility	27.10%	30.70%	28.60%
Expected dividend yield	2.50%	2.30%	3.00%
Risk free interest rate	1.80%	0.90%	0.60%
Expected forfeiture rate	5.00%	5.00%	4.80%
Expected stock option life | year	4.5	4.6	4.5
Stock options
Disclosure of terms and conditions of share-based payment arrangement [line items]
Intrinsic value of vested stock options	$ 195,000,000	$ 191,000,000	$ 10,000,000

INCOME TAXES - Schedule Of Prov

INCOME TAXES - Schedule Of Provision For Income Tax (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current
Other taxes	$ 11	$ 9	$ 11
Current income tax	(164)	(618)	(261)
Deferred
Deferred corporate income tax	586	(106)	216
Deferred income tax	640	(241)	231
Income tax expense (recovery)	476	(859)	(30)
North America
Current
Current corporate income tax	(145)	(377)	86
North Sea
Current
Current corporate income tax	57	(74)	(117)
Current PRT - North Sea	(132)	(198)	(258)
Deferred
Deferred PRT - North Sea	54	(135)	15
Offshore Africa
Current
Current corporate income tax	$ 45	$ 22	$ 17

INCOME TAXES - Schedule of Pr76

INCOME TAXES - Schedule of Provision For Income Tax Reconciliation (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of accounting profit multiplied by applicable tax rates [abstract]
Canadian statutory income tax rate	27.00%	27.00%	26.00%
Income tax provision at statutory rate	$ 776	$ (287)	$ (173)
UK PRT and other taxes	(67)	(324)	(232)
Impact of deductible UK PRT and other taxes on corporate income tax	28	131	119
Foreign and domestic tax rate differentials	(43)	(54)	(157)
Non-taxable portion of capital gains/losses	(86)	(80)	36
Stock options exercised for common shares	33	94	(12)
Income tax rate and other legislative changes	10	(107)	362
Non-taxable gain on corporate acquisitions	(63)	0	0
Revisions arising from prior year tax filings	(3)	(120)	32
Change in unrecognized capital loss carryforward asset	(86)	(80)	36
Other	(23)	(32)	(41)
Income tax expense (recovery)	$ 476	$ (859)	$ (30)

INCOME TAXES - Summary of Major

INCOME TAXES - Summary of Major Temporary Differences (Details) - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax liabilities	$ 12,859	$ 10,670
Deferred income tax assets	(1,884)	(1,597)
Net deferred income tax liability	10,975	9,073	$ 9,344	$ 8,970
Property, plant and equipment and exploration and evaluation assets
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax liabilities	12,484	10,259
Unrealized risk management activities
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax liabilities	20	62
PRT deduction for corporate income tax
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax liabilities	7	29
Investments
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax liabilities	96	98
Investment in North West Redwater Partnership
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax liabilities	252	222
Asset retirement obligations
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax assets	(1,264)	(983)
Loss carryforwards
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax assets	(523)	(390)
Unrealized foreign exchange loss (gain) on long-term debt
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax assets	(29)	(149)
Deferred PRT
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax assets	(18)	(73)
Other
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax assets	$ (50)	$ (2)

INCOME TAXES - Summary of Movem

INCOME TAXES - Summary of Movements in Deferred Tax Assets and Liabilities (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax expense (recovery)	$ 640	$ (241)	$ 231
Property, plant and equipment and exploration and evaluation assets
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax expense (recovery)	541	37	(7)
Timing of partnership items
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax expense (recovery)	0	(261)	(176)
Unrealized foreign exchange loss (gain) on long-term debt
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax expense (recovery)	120	63	(222)
Unrealized risk management activities
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax expense (recovery)	(46)	(44)	(5)
Asset retirement obligations
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax expense (recovery)	(88)	(20)	522
Loss carryforwards
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax expense (recovery)	48	(221)	(53)
Investments
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax expense (recovery)	(2)	38	60
Investment in North West Redwater Partnership
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax expense (recovery)	30	81	106
Deferred PRT
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax expense (recovery)	54	(135)	15
PRT deduction for corporate income tax
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax expense (recovery)	(21)	61	(5)
Other
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax expense (recovery)	$ 4	$ 160	$ (4)

INCOME TAXES - Summary of Net D

INCOME TAXES - Summary of Net Deferred Income Tax Liability (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of changes in deferred tax liability (asset) [abstract]
Balance – beginning of year	$ 9,073	$ 9,344	$ 8,970
Deferred income tax expense (recovery)	640	(241)	231
Deferred income tax expense (recovery) included in other comprehensive income	4	(5)	(4)
Foreign exchange adjustments	(29)	(25)	147
Business combinations (note 7)	1,287	0	0
Balance – end of year	$ 10,975	$ 9,073	$ 9,344

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - CAD ($) $ in Millions	6 Months Ended		12 Months Ended
	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Supplementary charge tax rate					10.00%	20.00%	32.00%
Decrease in deferred corporate tax liability					$ 107
Petroleum revenue tax rate					0.00%	35.00%	50.00%
Recovery PRT rate for prior taxation years					50.00%	50.00%
Decrease in deferred PRT liability					$ 228	$ 11
Increase in deferred corporate income tax liability due to change in PRT rate					$ 114
Provincial corporate income tax rate	12.00%	10.00%		11.00%
Increase in deferred income tax liability due to change in provincial corporate income tax rate				$ 10		579
Decrease in deferred income tax liability due to change in PRT and supplementary charge on oil and gas profits						$ (217)
Unused tax losses
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deductible temporary differences for which no deferred tax asset is recognised				1,000
Unused tax credits
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deductible temporary differences for which no deferred tax asset is recognised				$ 650
Changes in tax rate
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Provincial corporate income tax rate			12.00%

SHARE CAPITAL - Outstanding Com

SHARE CAPITAL - Outstanding Common Shares (Details) - CAD ($) shares in Thousands, $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of number of shares outstanding [abstract]
Balance – beginning of year		$ 26,267	$ 27,381
Issued upon exercise of stock options (in shares)		14,256	16,284
Balance – end of year		$ 31,653	$ 26,267	$ 27,381
Share capital
Reconciliation of number of shares outstanding [abstract]
Balance – beginning of year		4,671	4,541	4,432
Issued for the acquisition of AOSP and other assets (note 7)	[1]	3,818	0	0
Issued upon exercise of stock options		466	559	91
Previously recognized liability on stock options exercised for common shares		154	117	18
Return of capital on PrairieSky Royalty Ltd. share distribution		0	(546)	0
Balance – end of year		$ 9,109	$ 4,671	$ 4,541
Ordinary shares | Share capital
Reconciliation of number of shares outstanding [abstract]
Balance - beginning of year (in shares)		1,110,952	1,094,668
Balance – beginning of year		$ 4,671	$ 4,541
Issued for the acquisition of AOSP and other assets (note 7) (in shares)		97,561	0
Issued for the acquisition of AOSP and other assets (note 7)		$ 3,818	$ 0
Issued upon exercise of stock options (in shares)		14,256	16,284
Issued upon exercise of stock options		$ 466	$ 559
Previously recognized liability on stock options exercised for common shares		154	117
Return of capital on PrairieSky Royalty Ltd. share distribution		$ 0	$ (546)
Balance - end of year (in shares)		1,222,769	1,110,952	1,094,668
Balance – end of year		$ 9,109	$ 4,671	$ 4,541
[1]	During 2017, in connection with the acquisition of direct and indirect interests in the Athabasca Oil Sands Project ("AOSP") and other assets, the Company issued non-cash share consideration of $3,818 million. See note 7.

SHARE CAPITAL - Narrative (Deta

SHARE CAPITAL - Narrative (Details) - $ / shares	May 16, 2017	Mar. 01, 2017	Nov. 02, 2016	Mar. 02, 2016	Mar. 04, 2015	Dec. 31, 2017
Disclosure of terms and conditions of share-based payment arrangement [line items]
Quarterly dividend declared subsequent to year end (in CAD per share)						$ 0.335
Quarterly dividend declared (in CAD per share)		$ 0.275	$ 0.25	$ 0.23	$ 0.23
Shares authorized to be repurchased through Normal Course Issuer Bid (in shares)	27,931,135
Share repurchase term	12 months
Stock options
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting term						5 years
Shares that may be reserved for issuance as a percentage of common shares outstanding						9.00%
Stock options | Bottom of range
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiration term						5 years
Stock options | Top of range
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiration term						6 years

SHARE CAPITAL - Stock Option Ac

SHARE CAPITAL - Stock Option Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2017CAD ($)shares	Dec. 31, 2016CAD ($)shares
Share Capital, Reserves And Other Equity Interest [Abstract]
Stock options outstanding - beginning of year (in shares) | shares	58,299	74,615
Stock options granted (in shares) | shares	16,052	11,002
Stock options surrendered for cash settlement (in shares) | shares	(626)	(817)
Stock options exercised for common shares (in shares) | shares	(14,256)	(16,284)
Stock options forfeited (in shares) | shares	(3,433)	(10,217)
Stock options outstanding - end of year (in shares) | shares	56,036	58,299
Stock options exercisable (in shares) | shares	18,282	20,747
Weighted average exercise price, options outstanding - beginning of year (in CAD per share) | $	$ 34.22	$ 34.88
Weighted average exercise price, options granted (in CAD per share) | $	42.07	34.97
Weighted average exercise price, options surrendered for cash settlement (in CAD per share) | $	33.18	34.47
Weighted average exercise price, options exercised (in CAD per share) | $	32.66	34.31
Weighted average exercise price, options forfeited (in CAD per share) | $	37.53	39.66
Weighted average exercise price, options outstanding - end of year (in CAD per share) | $	36.67	34.22
Weighted average exercise price, options exercisable (in CAD per share) | $	$ 34.25	$ 33.75

SHARE CAPITAL - Range of Exerci

SHARE CAPITAL - Range of Exercise Prices of Stock Options (Details) shares in Thousands	Dec. 31, 2017CAD ($)sharesyear	Dec. 31, 2016CAD ($)shares	Dec. 31, 2015CAD ($)shares
Disclosure of range of exercise prices of outstanding share options [line items]
Stock options outstanding (in shares) | shares	56,036	58,299	74,615
Weighted average remaining term (years) | year	3.13
Weighted average exercise price, options outstanding (in CAD per share)	$ 36.67	$ 34.22	$ 34.88
Stock options exercisable (in shares) | shares	18,282	20,747
Weighted average exercise price, options exercisable (in CAD per share)	$ 34.25	$ 33.75
$22.90 - $24.99
Disclosure of range of exercise prices of outstanding share options [line items]
Stock options outstanding (in shares) | shares	3,657
Weighted average remaining term (years) | year	3.03
Weighted average exercise price, options outstanding (in CAD per share)	$ 22.90
Stock options exercisable (in shares) | shares	1,116
Weighted average exercise price, options exercisable (in CAD per share)	$ 22.90
$22.90 - $24.99 | Bottom of range
Disclosure of range of exercise prices of outstanding share options [line items]
Range of exercise prices	22.90
$22.90 - $24.99 | Top of range
Disclosure of range of exercise prices of outstanding share options [line items]
Range of exercise prices	$ 24.99
$25.00 - $29.99
Disclosure of range of exercise prices of outstanding share options [line items]
Stock options outstanding (in shares) | shares	8,390
Weighted average remaining term (years) | year	2.34
Weighted average exercise price, options outstanding (in CAD per share)	$ 28.72
Stock options exercisable (in shares) | shares	3,967
Weighted average exercise price, options exercisable (in CAD per share)	$ 28.57
$25.00 - $29.99 | Bottom of range
Disclosure of range of exercise prices of outstanding share options [line items]
Range of exercise prices	25
$25.00 - $29.99 | Top of range
Disclosure of range of exercise prices of outstanding share options [line items]
Range of exercise prices	$ 29.99
$30.00 - $34.99
Disclosure of range of exercise prices of outstanding share options [line items]
Stock options outstanding (in shares) | shares	10,047
Weighted average remaining term (years) | year	1.61
Weighted average exercise price, options outstanding (in CAD per share)	$ 33.31
Stock options exercisable (in shares) | shares	5,557
Weighted average exercise price, options exercisable (in CAD per share)	$ 33.49
$30.00 - $34.99 | Bottom of range
Disclosure of range of exercise prices of outstanding share options [line items]
Range of exercise prices	30
$30.00 - $34.99 | Top of range
Disclosure of range of exercise prices of outstanding share options [line items]
Range of exercise prices	$ 34.99
$35.00 - $39.99
Disclosure of range of exercise prices of outstanding share options [line items]
Stock options outstanding (in shares) | shares	13,523
Weighted average remaining term (years) | year	3.29
Weighted average exercise price, options outstanding (in CAD per share)	$ 37.21
Stock options exercisable (in shares) | shares	4,190
Weighted average exercise price, options exercisable (in CAD per share)	$ 35.88
$35.00 - $39.99 | Bottom of range
Disclosure of range of exercise prices of outstanding share options [line items]
Range of exercise prices	35
$35.00 - $39.99 | Top of range
Disclosure of range of exercise prices of outstanding share options [line items]
Range of exercise prices	$ 39.99
$40.00 - $44.99
Disclosure of range of exercise prices of outstanding share options [line items]
Stock options outstanding (in shares) | shares	19,417
Weighted average remaining term (years) | year	4.15
Weighted average exercise price, options outstanding (in CAD per share)	$ 43.60
Stock options exercisable (in shares) | shares	3,118
Weighted average exercise price, options exercisable (in CAD per share)	$ 43.55
$40.00 - $44.99 | Bottom of range
Disclosure of range of exercise prices of outstanding share options [line items]
Range of exercise prices	40
$40.00 - $44.99 | Top of range
Disclosure of range of exercise prices of outstanding share options [line items]
Range of exercise prices	$ 44.99
$45.00 - $46.74
Disclosure of range of exercise prices of outstanding share options [line items]
Stock options outstanding (in shares) | shares	1,002
Weighted average remaining term (years) | year	3.63
Weighted average exercise price, options outstanding (in CAD per share)	$ 45.61
Stock options exercisable (in shares) | shares	334
Weighted average exercise price, options exercisable (in CAD per share)	$ 45.09
$45.00 - $46.74 | Bottom of range
Disclosure of range of exercise prices of outstanding share options [line items]
Range of exercise prices	45
$45.00 - $46.74 | Top of range
Disclosure of range of exercise prices of outstanding share options [line items]
Range of exercise prices	$ 46.74

ACCUMULATED OTHER COMPREHENSI85

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Analysis Of Other Comprehensive Income By Item [Abstract]
Derivative financial instruments designated as cash flow hedges	$ 47	$ 27
Foreign currency translation adjustment	(115)	43
Accumulated other comprehensive income (loss)	$ (68)	$ 70

CAPITAL DISCLOSURES (Details)

CAPITAL DISCLOSURES (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of objectives, policies and processes for managing capital [line items]
Long-term debt, net	$ 22,321	$ 16,788
Equity	$ 31,653	$ 26,267	$ 27,381
Debt to book capitalization	41.00%	39.00%
Bottom of range
Disclosure of objectives, policies and processes for managing capital [line items]
Debt to book capitalization	25.00%
Top of range
Disclosure of objectives, policies and processes for managing capital [line items]
Debt to book capitalization	45.00%

NET EARNINGS (LOSS) PER COMMO87

NET EARNINGS (LOSS) PER COMMON SHARE - Schedule of Basic and Diluted Net Earnings (Loss) per Common Share(Details) - CAD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Weighted average ordinary shares and adjusted weighted average ordinary shares [abstract]
Effect of dilutive stock options (thousands of shares)	7,729	0	0
Weighted average common shares outstanding – basic (thousands of shares)	1,175,094	1,100,471	1,093,862
Weighted average common shares outstanding – diluted (thousands of shares)	1,182,823	1,100,471	1,093,862
Net earnings (loss)	$ 2,397	$ (204)	$ (637)
Net earnings (loss) per common share - basic (in CAD per share)	$ 2.04	$ (0.19)	$ (0.58)
Net earnings (loss) per common share - diluted (in CAD per share)	$ 2.03	$ (0.19)	$ (0.58)

NET EARNINGS (LOSS) PER COMMO88

NET EARNINGS (LOSS) PER COMMON SHARE - Narrative (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2017shares
Earnings per share [abstract]
Potentially anti-dilutive securities	17,547

INTEREST AND OTHER FINANCING 89

INTEREST AND OTHER FINANCING EXPENSE (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Borrowing costs [abstract]
Long-term debt	$ 810	$ 664	$ 618
Other	0	0	1
Interest and other financing expense	810	664	619
Less: amounts capitalized on qualifying assets	82	233	244
Total interest and other financing expense	728	431	375
Total interest income	(97)	(48)	(53)
Net interest and other financing expense	$ 631	$ 383	$ 322

FINANCIAL INSTRUMENTS - Carryin

FINANCIAL INSTRUMENTS - Carrying amounts of financial instruments by category (Details) $ in Millions, $ in Millions	Dec. 31, 2017USD ($)	Dec. 31, 2017CAD ($)	Dec. 31, 2016CAD ($)
Disclosure of detailed information about financial instruments [line items]
Financial assets at amortized cost		$ 2,907	$ 1,819
Fair value through profit or loss		855	917
Derivatives used for hedging		139	485
Financial liabilities at amortized cost		(26,299)	(19,622)
Total		(22,398)	(16,401)
Accounts payable
Disclosure of detailed information about financial instruments [line items]
Financial liabilities at amortized cost		(775)	(595)
Financial liabilities		(775)	(595)
Accrued liabilities
Disclosure of detailed information about financial instruments [line items]
Financial liabilities at amortized cost		(2,597)	(2,222)
Financial liabilities		(2,597)	(2,222)
Other long-term liabilities
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, fair value through profit or loss		(38)
Financial liabilities, derivatives used for hedging		(65)
Financial liabilities at amortized cost		(469)
Financial liabilities		(572)
Long-term debt
Disclosure of detailed information about financial instruments [line items]
Financial liabilities at amortized cost		(22,458)	(16,805)
Financial liabilities		(22,458)	(16,805)
Accounts receivable
Disclosure of detailed information about financial instruments [line items]
Financial assets at amortized cost		2,397	1,434
Financial assets		2,397	1,434
Investments
Disclosure of detailed information about financial instruments [line items]
Financial assets at amortized cost		0	0
Financial assets, fair value through profit or loss		893	913
Financial assets		893	913
Other long-term assets
Disclosure of detailed information about financial instruments [line items]
Financial assets at amortized cost		510	385
Financial assets, fair value through profit or loss		0	4
Financial assets, derivatives used for hedging		204	485
Financial assets		714	$ 874
AOSP
Disclosure of detailed information about financial instruments [line items]
Deferred purchase consideration payable	$ 375	$ 469

FINANCIAL INSTRUMENTS - Carry91

FINANCIAL INSTRUMENTS - Carrying amounts and fair values of financial instruments (Details) - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other long-term liabilities
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, carrying amount	$ (103)
Other long-term liabilities | Level 1
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, at fair value	0
Other long-term liabilities | Level 2
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, at fair value	103
Other long-term liabilities | Level 3
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, at fair value	0
Fixed rate long-term debt
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, carrying amount	(22,458)	$ (16,805)
Fixed rate long-term debt | Fixed interest rate
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, carrying amount	(15,989)	(12,498)
Fixed rate long-term debt | Fixed interest rate | Level 1
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, at fair value	(17,259)	(13,217)
Fixed rate long-term debt | Fixed interest rate | Level 2
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, at fair value	0	0
Fixed rate long-term debt | Fixed interest rate | Level 3
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, at fair value	0	0
Investments
Disclosure of detailed information about financial instruments [line items]
Financial assets, carrying amount	893	913
Investments | Level 1
Disclosure of detailed information about financial instruments [line items]
Financial assets, at fair value	893	913
Investments | Level 2
Disclosure of detailed information about financial instruments [line items]
Financial assets, at fair value	0	0
Investments | Level 3
Disclosure of detailed information about financial instruments [line items]
Financial assets, at fair value	0	0
Other long-term assets
Disclosure of detailed information about financial instruments [line items]
Financial assets, carrying amount	714	874
Other long-term assets | Level 1
Disclosure of detailed information about financial instruments [line items]
Financial assets, at fair value	0	0
Other long-term assets | Level 2
Disclosure of detailed information about financial instruments [line items]
Financial assets, at fair value	204	489
Other long-term assets | Level 3
Disclosure of detailed information about financial instruments [line items]
Financial assets, at fair value	$ 510	$ 385

FINANCIAL INSTRUMENTS - Carry92

FINANCIAL INSTRUMENTS - Carrying amounts and reconciliation of derivative financial instruments (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about hedging instruments [line items]
Derivative financial asset (liability), net	$ 101	$ 489	$ 854
Current portion of other long-term (liabilities) assets	(103)	222
Other long-term assets	204	267
Cash flow hedges
Disclosure of detailed information about hedging instruments [line items]
Gain (loss) on hedge ineffectiveness	5	7	$ 5
Forward contracts
Disclosure of detailed information about hedging instruments [line items]
Derivatives held for trading, asset (liability)	(38)	10
Forward contracts | Cash flow hedges
Disclosure of detailed information about hedging instruments [line items]
Cash flow hedges, asset (liability)	(71)	16
AECO swaps
Disclosure of detailed information about hedging instruments [line items]
Derivatives held for trading, asset (liability)	0	(6)
Cross currency swaps | Cash flow hedges
Disclosure of detailed information about hedging instruments [line items]
Cash flow hedges, asset (liability)	$ 210	$ 469

FINANCIAL INSTRUMENTS - Estimat

FINANCIAL INSTRUMENTS - Estimated fair values of derivative financial instruments included in risk management asset (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation Of Changes In Derivative Financial Assets (Liabilities), Net [Roll Forward]
Derivative financial asset (liability), net	$ 489	$ 854
Net change in fair value of outstanding derivatives financial instruments recognized in: Risk management activities	(37)	(25)	$ (374)
Net change in fair value of outstanding derivatives financial instruments recognized in: Foreign exchange	(375)	(304)
Net change in fair value of outstanding derivatives financial instruments recognized in: Other comprehensive income (loss)	24	(36)
Derivative financial asset (liability), net	101	489	$ 854
Asset (liability), included in current portion of other long-term (liabilities) assets	(103)	222
Asset (liability), included in other long-term assets	$ 204	$ 267

FINANCIAL INSTRUMENTS - Net (ga

FINANCIAL INSTRUMENTS - Net (gains) losses from risk management activities (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financial Instruments [Abstract]
Net realized risk management (gain) loss	$ (2)	$ 8	$ (843)
Net unrealized risk management loss	37	25	374
Gains (losses) on change in fair value of derivatives	$ (35)	(33)	469
Gains (losses) on change in fair value of derivatives		$ (33)	$ 469

FINANCIAL INSTRUMENTS - Foreign

FINANCIAL INSTRUMENTS - Foreign currency exchange rate risk management (Details) - Foreign currency exchange rate risk	12 Months Ended
	Dec. 31, 2017USD ($)$ / $
Cash flow hedges | Forward contracts
Disclosure of detailed information about hedging instruments [line items]
Notional amount	$ 2,339,000,000
Cross currency swaps | Cash flow hedges | Currency swap contract, term through November 2021
Disclosure of detailed information about hedging instruments [line items]
Amount	500
Exchange rate (US$/C$) | $ / $	1.022
Cross currency swaps | Cash flow hedges | Currency swap contract, term through March 2038
Disclosure of detailed information about hedging instruments [line items]
Amount	550
Exchange rate (US$/C$) | $ / $	1.170
Cross currency swaps | US | Cash flow hedges | Currency swap contract, term through November 2021
Disclosure of detailed information about hedging instruments [line items]
Interest rate	3.45%
Cross currency swaps | US | Cash flow hedges | Currency swap contract, term through March 2038
Disclosure of detailed information about hedging instruments [line items]
Interest rate	6.25%
Cross currency swaps | CAD | Cash flow hedges | Currency swap contract, term through November 2021
Disclosure of detailed information about hedging instruments [line items]
Interest rate	3.96%
Cross currency swaps | CAD | Cash flow hedges | Currency swap contract, term through March 2038
Disclosure of detailed information about hedging instruments [line items]
Interest rate	5.76%
Forward contracts
Disclosure of detailed information about hedging instruments [line items]
Notional amount	$ 3,705,000,000
Derivative, term of contract	90 days

FINANCIAL INSTRUMENTS - Financi

FINANCIAL INSTRUMENTS - Financial instrument sensitivities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017CAD ($)
Interest rate risk
Disclosure of detailed information about financial instruments [line items]
Increase (decrease) to net earnings		$ (42)
Increase (decrease) to net earnings		42
(Increase) decrease to other comprehensive loss		(16)
(Increase) decrease to other comprehensive loss		$ 19
Increase interest rate 1%	1.00%	1.00%
Decrease interest rate 1%	1.00%	1.00%
Foreign currency exchange rate risk
Disclosure of detailed information about financial instruments [line items]
Increase (decrease) to net earnings		$ (105)
Increase (decrease) to net earnings		101
(Increase) decrease to other comprehensive loss		0
(Increase) decrease to other comprehensive loss		$ 0
Increase exchange rate by US$0.01	$ 0.01
Decrease exchange rate by US$0.01	$ 0.01

FINANCIAL INSTRUMENTS - Counter

FINANCIAL INSTRUMENTS - Counterparty credit risk management (Details) - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about financial instruments [line items]
Derivative financial asset (liability), net	$ 101	$ 489	$ 854
Credit risk
Disclosure of detailed information about financial instruments [line items]
Derivative financial asset (liability), net	$ 187	$ 489

FINANCIAL INSTRUMENTS - Maturit

FINANCIAL INSTRUMENTS - Maturity dates for financial liabilities (Details) $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017CAD ($)	Dec. 31, 2016CAD ($)	Dec. 31, 2015CAD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017CAD ($)
Disclosure of detailed information about financial instruments [line items]
Accounts payable		$ 595			$ 775
Accrued liabilities		2,222			2,597
Other long-term liabilities		3,223			4,397
Long-term debt		16,805			22,458
Interest and other financing expense	$ 728	431	$ 375
AOSP
Disclosure of detailed information about financial instruments [line items]
Deferred purchase consideration payable				$ 375	469
Gross carrying amount
Disclosure of detailed information about financial instruments [line items]
Long-term debt		$ 16,870			22,597
Less than 1 year | Gross carrying amount
Disclosure of detailed information about financial instruments [line items]
Long-term debt					2,027
1 to less than 2 years | Gross carrying amount
Disclosure of detailed information about financial instruments [line items]
Long-term debt					4,228
Thereafter | Gross carrying amount
Disclosure of detailed information about financial instruments [line items]
Long-term debt					10,351
Liquidity risk | Less than 1 year
Disclosure of detailed information about financial instruments [line items]
Accounts payable					775
Accrued liabilities					2,597
Other long-term liabilities					572
Interest and other financing expense	842
Liquidity risk | Less than 1 year | Gross carrying amount
Disclosure of detailed information about financial instruments [line items]
Long-term debt					2,027
Liquidity risk | 1 to less than 2 years
Disclosure of detailed information about financial instruments [line items]
Accounts payable					0
Accrued liabilities					0
Other long-term liabilities					0
Interest and other financing expense	755
Liquidity risk | 1 to less than 2 years | Gross carrying amount
Disclosure of detailed information about financial instruments [line items]
Long-term debt					4,228
Liquidity risk | 2 to less than 5 years
Disclosure of detailed information about financial instruments [line items]
Accounts payable					0
Accrued liabilities					0
Other long-term liabilities					0
Interest and other financing expense	1,712
Liquidity risk | 2 to less than 5 years | Gross carrying amount
Disclosure of detailed information about financial instruments [line items]
Long-term debt					5,991
Liquidity risk | Thereafter
Disclosure of detailed information about financial instruments [line items]
Accounts payable					0
Accrued liabilities					0
Other long-term liabilities					0
Interest and other financing expense	$ 5,384
Liquidity risk | Thereafter | Gross carrying amount
Disclosure of detailed information about financial instruments [line items]
Long-term debt					$ 10,351

COMMITMENTS AND CONTINGENCIES99

COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017CAD ($)
2,018
Disclosure Of Commitments [Line Items]
Product transportation and pipeline	$ 680
Other	87
2,019
Disclosure Of Commitments [Line Items]
Product transportation and pipeline	584
Other	41
2,020
Disclosure Of Commitments [Line Items]
Product transportation and pipeline	526
Other	40
2,021
Disclosure Of Commitments [Line Items]
Product transportation and pipeline	482
Other	39
2,022
Disclosure Of Commitments [Line Items]
Product transportation and pipeline	422
Other	43
Thereafter
Disclosure Of Commitments [Line Items]
Product transportation and pipeline	3,868
Other	$ 333
North West Redwater Partnership
Disclosure Of Commitments [Line Items]
Percent of pro rata share of debt company has committed paying to joint venture	25.00%
Term of commitment to joint venture	30 years
Offshore equipment operating leases | 2018
Disclosure Of Commitments [Line Items]
Office leases	$ 181
Offshore equipment operating leases | 2019
Disclosure Of Commitments [Line Items]
Office leases	92
Offshore equipment operating leases | 2020
Disclosure Of Commitments [Line Items]
Office leases	70
Offshore equipment operating leases | 2021
Disclosure Of Commitments [Line Items]
Office leases	68
Offshore equipment operating leases | 2022
Disclosure Of Commitments [Line Items]
Office leases	8
Offshore equipment operating leases | Thereafter
Disclosure Of Commitments [Line Items]
Office leases	0
Office leases | 2018
Disclosure Of Commitments [Line Items]
Office leases	43
Office leases | 2019
Disclosure Of Commitments [Line Items]
Office leases	42
Office leases | 2020
Disclosure Of Commitments [Line Items]
Office leases	42
Office leases | 2021
Disclosure Of Commitments [Line Items]
Office leases	39
Office leases | 2022
Disclosure Of Commitments [Line Items]
Office leases	30
Office leases | Thereafter
Disclosure Of Commitments [Line Items]
Office leases	$ 118

SUPPLEMENTAL DISCLOSURE OF C100

SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION - Supplemental Schedule Of Cash Flow Information (Details) $ in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2017CAD ($)	Dec. 31, 2016CAD ($)	Dec. 31, 2015CAD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017CAD ($)
Disclosure Of Detailed Information About Cash Flows [Line Items]
Accounts receivable		$ (977)	$ (142)	$ 615
Current income tax assets		527	(165)	(447)
Inventory		81	(79)	142
Prepaids and other		(28)	14	11
Accounts payable		175	31	7
Accrued liabilities		365	(116)	(981)
Other long-term liabilities		469	0	0
Net changes in non-cash working capital		612	(457)	(653)
Net change in non-cash working capital		299	(542)	239
Net change in non-cash working capital		0	0	(40)
Net change in non-cash working capital, investing activities		313	85	(852)
Exploration and evaluation assets
Expenditures on exploration and evaluation assets		159	29	180
Net proceeds on sale of exploration and evaluation assets		(35)	(35)	(416)
Net expenditures (proceeds) on exploration and evaluation assets	[1]	124	(6)	(236)
Property, plant and equipment
Expenditures on property, plant and equipment		4,574	4,152	5,118
Net proceeds on sale of property, plant and equipment		0	(349)	(414)
Net expenditures on property, plant and equipment	[1],[2]	$ 4,574	3,803	4,704
Investment in PrairieSky Royalty Ltd.
Property, plant and equipment
Non-cash share consideration received				$ 985
Disposal of Cold Lake Pipeline | Investment in Inter Pipeline Ltd.
Property, plant and equipment
Non-cash share consideration received			$ 190
AOSP
Property, plant and equipment
Deferred purchase consideration payable					$ 375	$ 469
[1]	Net proceeds on exploration and evaluation assets and net expenditures on property, plant and equipment in 2015 exclude non-cash share consideration of $985 million received from PrairieSky Royalty Ltd. ("PrairieSky") on the disposition of royalty income assets.
[2]	Net expenditures on property, plant and equipment in 2016 exclude non-cash share consideration of $190 million received from Inter Pipeline Ltd. ("Inter Pipeline") on the disposition of the Company's interest in the Cold Lake Pipeline.

SUPPLEMENTAL DISCLOSURE OF C101

SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION - Liabilities Arising From Financing Activities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017CAD ($)
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Liabilities arising from financing activities, beginning balance	$ 16,320
Changes in liabilities arising from financing activities [abstract]
Issue of long-term debt	6,622
Settlement of hedge instruments, net	124
Non-cash changes	(747)
Liabilities arising from financing activities, ending balance	22,319
Cash flow hedges on US dollar debt securities
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Liabilities arising from financing activities, beginning balance	(485)
Changes in liabilities arising from financing activities [abstract]
Settlement of hedge instruments, net	124
Non-cash changes	222
Liabilities arising from financing activities, ending balance	(139)
Long-term debt
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Liabilities arising from financing activities, beginning balance	16,805
Changes in liabilities arising from financing activities [abstract]
Issue of long-term debt	6,622
Non-cash changes	(969)
Liabilities arising from financing activities, ending balance	$ 22,458

SEGMENTED INFORMATION - Narrati

SEGMENTED INFORMATION - Narrative (Details)	12 Months Ended
	Dec. 31, 2017segment
Operating Segments [Abstract]
Number of geographic segments	3

SEGMENTED INFORMATION - Operati

SEGMENTED INFORMATION - Operating Segments Earnings (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue [abstract]
Product sales	$ 17,669	$ 11,098	$ 13,167
Less: royalties	(1,018)	(575)	(804)
Revenue	16,651	10,523	12,363
Expenses
Production	5,596	4,099	4,726
Transportation, blending and feedstock	2,917	2,003	2,379
Depletion, depreciation and amortization	5,186	4,858	5,483
Asset retirement obligation accretion	164	142	173
Realized risk management activities	(2)	8	(843)
Gain on acquisition, disposition and revaluation of properties	(379)	(250)	(739)
(Gain) loss from investments	(38)	(327)	50
Administration	319	345	390
Share-based compensation	134	355	(46)
Interest and other financing expense	631	383	322
Net unrealized risk management loss	37	25	374
Foreign exchange (gain) loss	(787)	(55)	761
Total Expenses	13,778	11,586	13,030
Earnings (loss) before taxes	2,873	(1,063)	(667)
Current income tax recovery	(164)	(618)	(261)
Deferred income tax expense (recovery)	640	(241)	231
Net earnings (loss)	2,397	(204)	(637)
Inter–segment elimination and other
Revenue [abstract]
Product sales	(82)	(55)	(75)
Less: royalties	0	0	0
Revenue	(82)	(55)	(75)
Expenses
Production	(8)	(7)	(8)
Transportation, blending and feedstock	(85)	(68)	(75)
Depletion, depreciation and amortization	0	0	0
Asset retirement obligation accretion	0	0	0
Realized risk management activities	0	0	0
Gain on acquisition, disposition and revaluation of properties	0	0	0
(Gain) loss from investments	0	0	0
Total Expenses	(93)	(75)	(83)
Earnings (loss) before taxes	11	20	8
Non-segmented
Expenses
Administration	319	345	390
Share-based compensation	134	355	(46)
Interest and other financing expense	631	383	322
Net unrealized risk management loss	37	25	374
Foreign exchange (gain) loss	(787)	(55)	761
Total Expenses	334	1,053	1,801
Total Segments
Revenue [abstract]
Product sales	17,669	11,098	13,167
Less: royalties	(1,018)	(575)	(804)
Revenue	16,651	10,523	12,363
Expenses
Production	5,596	4,099	4,726
Transportation, blending and feedstock	2,917	2,003	2,379
Depletion, depreciation and amortization	5,186	4,858	5,483
Asset retirement obligation accretion	164	142	173
Realized risk management activities	(2)	8	(843)
Gain on acquisition, disposition and revaluation of properties	(379)	(250)	(739)
(Gain) loss from investments	(38)	(327)	50
Total Expenses	13,444	10,533	11,229
Earnings (loss) before taxes	3,207	(10)	1,134
North America | Operating segments
Revenue [abstract]
Product sales	9,161	7,209	9,222
Less: royalties	(809)	(524)	(732)
Revenue	8,352	6,685	8,490
Expenses
Production	2,362	2,186	2,603
Transportation, blending and feedstock	2,291	1,941	2,309
Depletion, depreciation and amortization	3,243	3,465	4,248
Asset retirement obligation accretion	80	66	93
Realized risk management activities	(2)	8	(843)
Gain on acquisition, disposition and revaluation of properties	(35)	(32)	(739)
(Gain) loss from investments	(7)	(320)	6
Total Expenses	7,932	7,314	7,677
Earnings (loss) before taxes	420	(629)	813
North Sea | Operating segments
Revenue [abstract]
Product sales	784	570	638
Less: royalties	(1)	(1)	(1)
Revenue	783	569	637
Expenses
Production	400	403	544
Transportation, blending and feedstock	31	48	61
Depletion, depreciation and amortization	509	458	388
Asset retirement obligation accretion	27	35	39
Realized risk management activities	0	0	0
Gain on acquisition, disposition and revaluation of properties	0	0	0
(Gain) loss from investments	0	0	0
Total Expenses	967	944	1,032
Earnings (loss) before taxes	(184)	(375)	(395)
Offshore Africa | Operating segments
Revenue [abstract]
Product sales	632	603	482
Less: royalties	(41)	(26)	(22)
Revenue	591	577	460
Expenses
Production	226	200	223
Transportation, blending and feedstock	1	2	2
Depletion, depreciation and amortization	205	262	273
Asset retirement obligation accretion	9	12	10
Realized risk management activities	0	0	0
Gain on acquisition, disposition and revaluation of properties	0	0	0
(Gain) loss from investments	0	0	0
Total Expenses	441	476	508
Earnings (loss) before taxes	150	101	(48)
Oil Sands Mining and Upgrading | Operating segments
Revenue [abstract]
Product sales	7,072	2,657	2,764
Less: royalties	(167)	(24)	(49)
Revenue	6,905	2,633	2,715
Expenses
Production	2,600	1,292	1,332
Transportation, blending and feedstock	679	80	82
Depletion, depreciation and amortization	1,220	662	562
Asset retirement obligation accretion	48	29	31
Realized risk management activities	0	0	0
Gain on acquisition, disposition and revaluation of properties	(230)	0	0
(Gain) loss from investments	0	0	0
Total Expenses	4,317	2,063	2,007
Earnings (loss) before taxes	2,588	570	708
Midstream | Operating segments
Revenue [abstract]
Product sales	102	114	136
Less: royalties	0	0	0
Revenue	102	114	136
Expenses
Production	16	25	32
Transportation, blending and feedstock	0	0	0
Depletion, depreciation and amortization	9	11	12
Asset retirement obligation accretion	0	0	0
Realized risk management activities	0	0	0
Gain on acquisition, disposition and revaluation of properties	(114)	(218)	0
(Gain) loss from investments	(31)	(7)	44
Total Expenses	(120)	(189)	88
Earnings (loss) before taxes	$ 222	$ 303	$ 48

SEGMENTED INFORMATION - Capital

SEGMENTED INFORMATION - Capital Expenditures (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	May 31, 2017
Exploration and evaluation assets
Net expenditures (proceeds)	$ 317	$ 26
Non-cash and fair value changes	(67)	(229)
Capitalized costs	250	(203)
Property, plant and equipment
Net expenditures (proceeds)	12,755	3,831
Non-cash and fair value changes	6,029	(53)
Capitalized costs	18,784	3,778
Non-segmented
Property, plant and equipment
Net expenditures (proceeds)	19	17
Non-cash and fair value changes	0	0
Capitalized costs	19	17
North America
Property, plant and equipment
Gain on sale of exploration and evaluation assets	35	32
North America | Operating segments
Exploration and evaluation assets
Net expenditures (proceeds)	160	17
Non-cash and fair value changes	(184)	(211)
Capitalized costs	(24)	(194)
Property, plant and equipment
Net expenditures (proceeds)	2,815	1,143
Non-cash and fair value changes	354	(36)
Capitalized costs	3,169	1,107
North Sea | Operating segments
Exploration and evaluation assets
Net expenditures (proceeds)	0	0
Non-cash and fair value changes	0	0
Capitalized costs	0	0
Property, plant and equipment
Net expenditures (proceeds)	160	126
Non-cash and fair value changes	95	60
Capitalized costs	255	186
Offshore Africa | Operating segments
Exploration and evaluation assets
Net expenditures (proceeds)	15	9
Non-cash and fair value changes	0	(18)
Capitalized costs	15	(9)
Property, plant and equipment
Net expenditures (proceeds)	89	142
Non-cash and fair value changes	12	(26)
Capitalized costs	101	116
Exploration and Production | Operating segments
Property, plant and equipment
Net expenditures (proceeds)	3,064	1,411
Non-cash and fair value changes	461	(2)
Capitalized costs	3,525	1,409
Oil Sands Mining and Upgrading | Operating segments
Exploration and evaluation assets
Net expenditures (proceeds)	142	0
Non-cash and fair value changes	117	0
Capitalized costs	259	0
Property, plant and equipment
Net expenditures (proceeds)	9,592	2,718
Non-cash and fair value changes	5,454	(23)
Capitalized costs	15,046	2,695
Midstream
Property, plant and equipment
Pre-tax gain on sale of properties		218
Pre-tax non-cash revaluation gain	114
After-tax non-cash revaluation gain	83
Midstream | Operating segments
Property, plant and equipment
Net expenditures (proceeds)	80	(315)
Non-cash and fair value changes	114	(28)
Capitalized costs	194	$ (343)
AOSP
Property, plant and equipment
Non-cash share considerations issued on the acquisition of AOSP and other assets	$ 3,818		$ 3,818

SEGMENTED INFORMATION - Segment

SEGMENTED INFORMATION - Segmented Assets (Details) - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of operating segments [line items]
Assets	$ 73,867	$ 58,648
Non-segmented
Disclosure of operating segments [line items]
Assets	110	114
North America | Operating segments
Disclosure of operating segments [line items]
Assets	28,705	28,892
North Sea | Operating segments
Disclosure of operating segments [line items]
Assets	1,854	2,269
Offshore Africa | Operating segments
Disclosure of operating segments [line items]
Assets	1,331	1,580
Other | Operating segments
Disclosure of operating segments [line items]
Assets	29	29
Oil Sands Mining and Upgrading | Operating segments
Disclosure of operating segments [line items]
Assets	40,559	24,852
Midstream | Operating segments
Disclosure of operating segments [line items]
Assets	$ 1,279	$ 912

REMUNERATION OF DIRECTORS AN106

REMUNERATION OF DIRECTORS AND SENIOR MANAGEMENT (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Non-management directors
Disclosure of transactions between related parties [line items]
Fees earned and salary	$ 3	$ 2	$ 2
Senior management
Disclosure of transactions between related parties [line items]
Fees earned and salary	3	3	3
Common stock option based awards	10	9	7
Annual incentive plans	5	5	2
Long-term incentive plans	17	15	6
Total	$ 35	$ 32	$ 18