Husky Energy (CVE+A) 40-F 9 Feb 21 2020 FY Annual report (Canada) Financial data

DEI Document

DEI Document	12 Months Ended
	Dec. 31, 2020shares
Document Information [Abstract]
Document Type	40-F
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	Husky Energy Inc.
Entity Central Index Key	0000049279
Amendment Flag	false
Entity Emerging Growth Company	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding	1,005,120,012

Consolidated Balance Sheets

Consolidated Balance Sheets $ in Millions, $ in Millions	Dec. 31, 2020CAD ($)	Dec. 31, 2019CAD ($)
Current assets
Cash and cash equivalents (note 4)	$ 735	$ 1,775
Accounts receivable (notes 5, 25)	1,119	1,499
Income taxes receivable	0	30
Inventories (note 6)	1,115	1,486
Prepaid expenses	161	148
Current assets	3,130	4,938
Non-current assets
Restricted cash (notes 7, 18)	164	142
Exploration and evaluation assets (note 8)	46	643
Property, plant and equipment, net (note 9)	13,496	23,623
Right-of-use assets	698	1,202
Goodwill (note 11)	0	656
Investment in joint ventures (note 12)	457	1,182
Long-term income taxes receivable	202	212
Deferred tax assets (note 13)	1,328	0
Deferred tax liability	990	(2,170)
Other assets (note 14)	166	524
Total Assets	19,687	33,122
Current liabilities
Accounts payable and accrued liabilities (note 16)	2,129	3,465
Current tax liabilities, current	27	0
Short-term debt (notes 15, 17)	40
Long-term debt due within one year (note 17)	0	400
Current lease liabilities	102	109
Asset retirement obligations (note 16)	94	112
Current liabilities	2,392	4,636
Non-current liabilities
Long-term debt (note 15)	6,117	4,570
Other long-term liabilities (note 17)	410	454
Asset retirement obligations (note 16)	2,068	2,643
Non-current lease liabilities	1,298	1,353
Non-current lease liabilities	(1,298)	(1,353)
Deferred tax liabilities	338	2,170
Total Liabilities	12,623	15,826
Shareholders’ equity
Common shares (note 20)	7,293	7,293
Preferred shares (note 20)	874	874
Contributed surplus	2	2
Retained earnings (deficit)	(1,855)	8,365
Accumulated other comprehensive income	735	748
Non-controlling interest	15	14
Total Shareholders’ Equity	7,064	17,296
Total Liabilities and Shareholders’ Equity	$ 19,687	$ 33,122

Consolidated Statements of Inco

Consolidated Statements of Income - CAD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Profit or loss [abstract]
Revenue from sale of goods	$ 13,463	$ 20,047
Royalties	(191)	(323)
Marketing and Other Contra Revenue Items	29	178
Revenues, net of royalties	13,301	19,902
Purchases of crude oil and products(1)	9,281	12,826
Production, operating and transportation expenses(1) (note 21)	2,560	3,030
Selling, general and administrative expenses (note 21)	745	693
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	12,920	5,496
Exploration and evaluation expenses (note 8)	733	547
Gain on sale of assets	(25)	(8)
Other – net(1) (notes 14, 25, 26)	(262)	(687)
Operating expense	25,952	21,897
Loss from operating activities	(12,651)	(1,995)
Share of equity investment income (note 12)	7	59
Net foreign exchange gain	14	44
Finance income	25	74
Finance expenses	(399)	(351)
Financial Items	(360)	(233)
Loss before income taxes	(13,004)	(2,169)
Provisions for (recovery of) income taxes. current	202	175
Provisions for (recovery of) income taxes, deferred	(3,190)	(974)
Provisions for (recovery of) income taxes	(2,988)	(799)
Net loss	$ (10,016)	$ (1,370)
Loss per share (note 20)
Loss per share – basic ($/share)	$ (10)	$ (1.40)
Loss per share – diluted ($/share)	$ (10)	$ (1.41)
Weighted average number of common shares outstanding (note 20)
Weighted average number of common shares outstanding, basic	1,005.1	1,005.1
Weighted average number of common shares outstanding, diluted	1,005.1	1,005.1

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) Statement - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statement of comprehensive income [abstract]
Net loss	$ (10,016)	$ (1,370)
Items that will not be reclassified into earnings, net of tax:
Remeasurements of pension plans (note 23)	(6)	0
Items that may be reclassified into earnings, net of tax:
Derivatives designated as cash flow hedge	0	(6)
Equity investment – share of other comprehensive loss	(8)	(2)
Exchange differences on translation of foreign operations	(49)	(550)
Hedge of net investment (note 25)	44	146
Other comprehensive loss	(19)	(412)
Comprehensive loss	$ (10,035)	$ (1,782)

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders Equity - CAD ($) $ in Millions	Total	Common Shares	Preferred Shares	Total Shareholders’ Equity	Total Shareholders’ EquityCommon Shares	Total Shareholders’ EquityPreferred Shares	Non-Controlling Interest	Issued capitalCommon Shares	Issued capitalPreferred Shares	Contributed Surplus	Retained Earnings (deficit)	Retained Earnings (deficit)Common Shares	Retained Earnings (deficit)Preferred Shares	Foreign Currency Translation	Hedging
Equity, beginning at Dec. 31, 2018				$ 19,614			$ 12	$ 7,293	$ 874	$ 2	$ 10,273			$ 1,154	$ 6
Net loss	$ (1,370)			(1,370)							(1,370)
Remeasurements of pension plans	0			0							0
Derivatives designated as cash flow hedges	(6)			(6)											(6)
Equity investment - share of other comprehensive income	(2)			(2)											(2)
Exchange differences on translation of foreign operations	(550)			(550)										(550)
Other comprehensive income, net of tax, gains (losses) on hedging instruments that hedge investments in equity instruments				146										146
Comprehensive income	(1,782)			(1,782)							(1,370)			(404)	(8)
Dividends declared on common and preferred shares (note 19)		$ 503	$ 35		$ (503)	$ (35)						$ (503)	$ (35)
Equity, ending at Dec. 31, 2019	17,296			17,296			14	7,293	874	2	8,365			750	(2)
Net loss	(10,016)			(10,016)							(10,016)
Remeasurements of pension plans	(6)			(6)
Derivatives designated as cash flow hedges	0			0											0
Equity investment - share of other comprehensive income	(8)			(8)											(8)
Exchange differences on translation of foreign operations	(49)			(49)										(49)
Other comprehensive income, net of tax, gains (losses) on hedging instruments that hedge investments in equity instruments				44										44
Comprehensive income	(10,035)			(10,035)							(10,022)			(5)	(8)
Dividends declared on common and preferred shares (note 19)		$ 163	$ 35		$ (163)	$ (35)						$ (163)	$ (35)
Non-controlling interests				1			1				0
Equity, ending at Dec. 31, 2020	$ 7,064			$ 7,064			$ 15	$ 7,293	$ 874	$ 2	$ (1,855)			$ 745	$ (10)

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Shareholders Equity (Parenthetical) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statement of changes in equity [abstract]
Remeasurement of pension plans	$ 2	$ (1)
Derivatives designated as cash flow hedges	3	3
Exchange differences on translation of foreign operations	(29)	58
Hedge of net investment	$ (6)	$ (30)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net loss	$ (10,016)	$ (1,370)
Accretion (notes 18, 22)	104	106
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	12,920	5,496
Inventory write-down to net realizable value (note 6)	7	15
Exploration and evaluation expenses (note 8)	594	355
Deferred income taxes (note 13)	(3,190)	(974)
Foreign exchange	(3)	(26)
Stock-based compensation (notes 20, 21)	16	(2)
Gain on sale of assets	(25)	(8)
Unrealized mark to market loss (note 25)	10	44
Share of equity investment income (note 12)	(7)	(59)
Income from reimbursements under insurance policies	(19)	(207)
Other	67	12
Settlement of asset retirement obligations (note 18)	(39)	(276)
Deferred revenue (notes 17, 19)	(115)	(42)
Distribution from joint ventures (note 12)	190	187
Change in non-cash working capital (note 24)	347	(280)
Cash flow – operating activities	841	2,971
Financing activities
Long-term debt issuance (repayment) (note 17)	1,200	(389)
Proceeds from current borrowings	(510)	350
Debt issue costs (note 17)	(7)	(9)
Payments of finance lease liabilities, classified as financing activities	(111)	(233)
Other	2	(1)
Change in non-cash working capital (note 24)	11	3
Cash flow – financing activities	274	(817)
Investing activities
Capital expenditures	(1,587)	(3,432)
Capitalized interest (note 22)	(60)	(177)
Proceeds from asset sales (note 9)	30	277
Investment in joint ventures (note 12)	(91)	(40)
Other	2	2
Change in non-cash working capital (note 24)	(423)	173
Cash flow – investing activities	(2,129)	(3,197)
Decrease in cash and cash equivalents	(1,014)	(1,043)
Effect of exchange rates on cash and cash equivalents	(26)	(48)
Cash and cash equivalents at beginning of year	1,775	2,866
Cash and cash equivalents at end of year	735	1,775
Net interest paid	(302)	(330)
Net Income taxes paid	(135)	(41)
Ordinary shares [member]
Financing activities
Dividends paid, classified as financing activities	(276)	(503)
Preference shares [member]
Financing activities
Dividends paid, classified as financing activities	$ (35)	$ (35)

Description of Business and Seg

Description of Business and Segmented Disclosures	12 Months Ended
	Dec. 31, 2020
Corporate Information And Statement Of IFRS Compliance [Abstract]
Description of Business and Segment Disclosures	Description of Business and Segmented Disclosures Husky Energy Inc. (“Husky” or “the Company”) is an international integrated energy company incorporated under the Business Corporations Act (Alberta). The Company’s common shares were listed on the Toronto Stock Exchange (“TSX”) under the symbol “HSE” and the Cumulative Redeemable Preferred Shares, Series 1, Cumulative Redeemable Preferred Shares, Series 2, Cumulative Redeemable Preferred Shares, Series 3, Cumulative Redeemable Preferred Shares, Series 5 and Cumulative Redeemable Preferred Shares, Series 7 were listed under the symbols, ”HSE.PR.A”, “HSE.PR.B”, ”HSE.PR.C”, ”HSE.PR.E” and ”HSE.PR.G”, respectively. The registered office is located at 39th Flr, 707 - 8th Avenue SW, Calgary, Alberta, T2P 3G7. On January 4, 2021, Husky announced the transaction to strategically combine with Cenovus Energy Inc. ("Cenovus") had closed. Husky's common shares and preferred shares were delisted by the TSX at the close of market on January 5, 2021. The combined company operates as Cenovus Energy Inc. These consolidated financial statements and notes are presented for Husky Energy Inc. and its consolidated entities without giving effect to the combination with Cenovus. Management has identified segments for the Company’s business based on differences in products, services and management responsibility. The Company’s business is conducted predominantly through two major business segments – Integrated Corridor and Offshore. Integrated Corridor The Company’s business in the Integrated Corridor includes: The Lloydminster Heavy Oil Value Chain includes the exploration for, and development and production of, heavy crude oil and bitumen, and production of ethanol. Blended heavy crude oil and bitumen are either sold directly to the Canadian market or transported utilizing the Husky Midstream Limited Partnership ("HMLP") pipeline systems to the Keystone pipeline and other pipelines to be sold in the U.S. downstream market. Heavy crude oil can be upgraded at the Company’s Lloydminster upgrading and asphalt refining complex into synthetic crude oil, diesel fuel and asphalt. This business also includes the marketing and transportation of both the Company’s own production and third-party commodity trading volumes of heavy crude oil, synthetic crude oil, asphalt and ancillary products. The sale and transportation of the Company’s production and third-party commodity trading volumes are managed through access to capacity on third-party pipelines and storage facilities in both Canada and the U.S. The Company is able to capture price differences between the two markets by utilizing infrastructure capacity to deliver production and/or third-party commodity trading volumes from Canada to the U.S. market. The Oil Sands business includes the exploration for, and development and production of, bitumen within the Sunrise Energy Project. It also includes the marketing and transportation of the Company’s and third-party production of bitumen through access to capacity on third-party pipelines and storage facilities in both Canada and the U.S. The Western Canada Production business includes the exploration for, and development and production of, light crude oil, conventional natural gas and natural gas liquids ("NGL") in Western Canada. The Company’s conventional natural gas and NGL production is marketed and transported with other third-party commodity trading volumes through access to capacity on third-party pipelines, export terminals and storage facilities which provides flexibility for market access. The U.S. Refining business includes the refining of crude oil at the Lima Refinery, the BP-Husky Toledo Refinery and the Superior Refinery in the U.S. Midwest to produce diesel fuel, gasoline, jet fuel, asphalt and other products. The Company also markets its own and third-party volumes of refined petroleum products including gasoline and diesel fuel. The Canadian Refined Products business includes the marketing of its own and third-party volumes of refined petroleum products, including gasoline and diesel, through petroleum outlets. Offshore The Company’s Offshore business includes operations, development and exploration in Asia Pacific and Atlantic. The price received for Asia Pacific production is largely based on long-term contracts and crude oil production from Atlantic is primarily driven by the price of Brent.
Disclosure of entity's operating segments [text block]	Segmented Financial Information Integrated Corridor ($ millions) Lloydminster Heavy Oil Value Chain (1) Oil Sands Western Canada Production U.S. Refining Years ended December 31, 2020 2019 2020 2019 2020 2019 2020 2019 Gross revenues (3) 3,753 5,601 306 649 367 514 6,636 10,253 Royalties (92) (160) (2) (13) (10) (41) — — Marketing and other (3) 22 52 (48) 4 15 99 40 23 Revenues, net of royalties 3,683 5,493 256 640 372 572 6,676 10,276 Expenses Purchases of crude oil and products (3) 1,827 2,395 153 246 22 40 6,500 8,934 Production, operating and transportation expenses (3) 1,059 1,212 114 140 250 313 797 872 Selling, general and administrative expenses 204 155 24 27 64 106 72 51 Depletion, depreciation, amortization and impairment 2,058 941 1,749 938 802 1,034 4,419 735 Exploration and evaluation expenses 182 54 (1) 2 1 111 — — Loss (gain) on sale of assets (4) — — — (20) (2) — 1 Other – net (3) 21 9 (26) (28) (7) 1 (84) (654) 5,347 4,766 2,013 1,325 1,112 1,603 11,704 9,939 Earnings (loss) from operating activities (1,664) 727 (1,757) (685) (740) (1,031) (5,028) 337 Share of equity investment income (loss) (32) 9 — — — — — — Financial items Net foreign exchange gain — — — — — — — — Finance income — — — — — — — — Finance expenses (47) (48) (57) (59) (19) (24) (18) (18) (47) (48) (57) (59) (19) (24) (18) (18) Earnings (loss) before income taxes (1,743) 688 (1,814) (744) (759) (1,055) (5,046) 319 Provisions for (recovery of) income taxes Current — (2) — 10 — — — 17 Deferred (434) 186 (452) (209) (189) (283) (1,121) 54 (434) 184 (452) (199) (189) (283) (1,121) 71 Net earnings (loss) (1,309) 504 (1,362) (545) (570) (772) (3,925) 248 (1) Includes $110 million of revenue (2019 - $201 million) and $99 million of associated costs (2019 - $269 million) for construction contracts in progress with revenue recognized as performance obligations are met. (2) Eliminations relate to sales and operating revenues between segments recorded at transfer prices based on current market prices. Segment results include transactions between business segments. (3) Results for certain items in the consolidated statements of loss reported for 2019 have been recast to reflect various reclassifications due to a change in presentation of the Integrated Corridor and Offshore business units. Segmented Financial Information Con’t Integrated Corridor Offshore Corporate Total Canadian Refined Products Eliminations (2) Total 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 1,488 2,425 (602) (948) 11,948 18,494 1,515 1,553 — — 13,463 20,047 — — — — (104) (214) (87) (109) — — (191) (323) — — — — 29 178 — — — — 29 178 1,488 2,425 (602) (948) 11,873 18,458 1,428 1,444 — — 13,301 19,902 1,349 2,175 (602) (948) 9,249 12,842 32 (16) — — 9,281 12,826 65 153 — — 2,285 2,690 275 340 — — 2,560 3,030 44 9 — — 408 348 75 55 262 290 745 693 62 83 — — 9,090 3,731 3,738 1,661 92 104 12,920 5,496 — — — — 182 167 551 380 — — 733 547 — (6) — — (24) (7) (1) (1) — — (25) (8) (4) — — — (100) (672) (5) 1 (157) (16) (262) (687) 1,516 2,414 (602) (948) 21,090 19,099 4,665 2,420 197 378 25,952 21,897 (28) 11 — — (9,217) (641) (3,237) (976) (197) (378) (12,651) (1,995) — — — — (32) 9 39 50 — — 7 59 — — — — — — — — 14 44 14 44 — — — — — — 7 3 18 71 25 74 (11) (13) — — (152) (162) (41) (38) (206) (151) (399) (351) (11) (13) — — (152) (162) (34) (35) (174) (36) (360) (233) (39) (2) — — (9,401) (794) (3,232) (961) (371) (414) (13,004) (2,169) — — — — — 25 150 125 52 25 202 175 (10) — — — (2,206) (252) (963) (393) (21) (329) (3,190) (974) (10) — — — (2,206) (227) (813) (268) 31 (304) (2,988) (799) (29) (2) — — (7,195) (567) (2,419) (693) (402) (110) (10,016) (1,370) Segmented Financial Information Integrated Corridor ($ millions) Lloydminster Heavy Oil Value Chain Oil Sands Western Canada Production Years ended December 31, 2020 2019 2020 2019 2020 2019 Expenditures on exploration and evaluation assets (1) — 17 — — — 3 Expenditures on property, plant and equipment (1) 594 939 9 38 57 191 As at December 31, Exploration and evaluation assets — 154 — — — 2 Developing and producing assets at cost 15,212 15,453 3,021 3,104 12,849 13,300 Accumulated depletion, depreciation, amortization and impairment (11,411) (10,345) (2,498) (1,020) (12,207) (11,764) Other property, plant and equipment at cost 4,189 3,820 76 3 55 62 Accumulated depletion, depreciation and amortization (2,752) (2,410) (9) — (30) (40) Total exploration and evaluation assets and property, plant and equipment, net 5,238 6,672 590 2,087 667 1,560 Total right-of-use assets, net 68 54 167 430 4 9 Total assets 6,650 8,312 993 2,757 707 1,709 (1) Excludes capitalized costs related to asset retirement obligations and capitalized interest incurred during the year. Includes assets acquired through acquisition, but excludes assets acquired through corporate acquisition. Geographical Financial Information ($ millions) Canada United States Years ended December 31, 2020 2019 2020 2019 Gross revenues (1)(2) 5,648 8,734 6,636 10,253 Royalties (122) (263) — — Marketing and other (2) (11) 155 40 23 Revenue, net of royalties 5,515 8,626 6,676 10,276 As at December 31, Restricted cash – non-current — — — — Exploration and evaluation assets — 599 — — Property, plant and equipment, net 7,893 14,630 2,868 6,053 Right-of-use assets, net 616 1,044 81 156 Goodwill — — — 656 Investment in joint ventures — 666 — — Long-term income tax receivable 202 212 — — Deferred tax assets 1,127 — 187 — Other assets (3) 30 47 119 458 Total non-current assets 9,868 17,198 3,255 7,323 (1) Sales to external customers are based on the location of the seller. (2) Results reported for 2019 have been recast to reflect various reclassifications due to a change in presentation of the Integrated Corridor and Offshore business units. (3) Includes insurance proceeds of $98 million (2019 - $435 million), related to the Superior Refinery incident. Segmented Financial Information Con’t Integrated Corridor Offshore Corporate Total U.S. Refining Canadian Refined Products Eliminations Total 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 — — — — — — — 20 1 26 — — 1 46 489 768 5 73 — — 1,154 2,009 367 1,246 65 131 1,586 3,386 — — — — — — — 156 46 487 — — 46 643 — — — — — — 31,082 31,857 15,102 14,730 — — 46,184 46,587 — — — — — — (26,116) (23,129) (11,773) (8,219) — — (37,889) (31,348) 10,057 9,540 1,287 1,284 — — 15,664 14,709 7 7 1,388 1,377 17,059 16,093 (7,190) (3,488) (794) (743) — — (10,775) (6,681) — — (1,083) (1,028) (11,858) (7,709) 2,867 6,052 493 541 — — 9,855 16,912 3,382 7,005 305 349 13,542 24,266 82 157 102 122 — — 423 772 3 138 272 292 698 1,202 4,469 8,645 625 838 — — 13,444 22,261 4,570 8,077 1,673 2,784 19,687 33,122 Geographical Financial Information Con’t China Other International Total 2020 2019 2020 2019 2020 2019 1,179 1,060 — — 13,463 20,047 (69) (60) — — (191) (323) — — — — 29 178 1,110 1,000 — — 13,301 19,902 164 142 — — 164 142 41 39 5 5 46 643 2,735 2,938 — 2 13,496 23,623 1 2 — — 698 1,202 — — — — — 656 — — 457 516 457 1,182 — — — — 202 212 — — 14 — 1,328 — — — 17 19 166 524 2,941 3,121 493 542 16,557 28,184 Disaggregation of Revenue Integrated Corridor ($ millions) Lloydminster Heavy Oil Value Chain Oil Sands Western Canada Production U.S. Refining Years ended December 31, 2020 2019 2020 2019 2020 2019 2020 2019 Primary Geographical Markets Canada 3,753 5,601 306 649 367 514 — — United States — — — — — — 6,636 10,253 China — — — — — — — — Total revenue 3,753 5,601 306 649 367 514 6,636 10,253 Major Product Lines (1) Synthetic crude oil 981 1,495 — — — — — — Gasoline — — — — — — 3,453 5,414 Diesel & distillates 170 260 — — — — 2,282 3,644 Asphalt 475 609 — — — — 85 136 Total upgraded and refined products 1,626 2,364 — — — — 5,820 9,194 Diluted bitumen — — 308 640 — — — — Blended crude oil 1,500 2,197 — — — — — — Light & medium crude oil — — — — 82 167 — — NGL — — — — 101 168 — — Natural gas — — — — 153 162 — — Total unrefined products 1,500 2,197 308 640 336 497 — — Other 627 1,040 (2) 9 31 17 816 1,059 Total revenue 3,753 5,601 306 649 367 514 6,636 10,253 (1) Results reported for 2019 have been recast to reflect a change in reclassification of intersegment sales eliminations and a change in presentation of the Integrated Corridor and Offshore business units. Disaggregation of Revenue Con’t Integrated Corridor Offshore Corporate Total Canadian Refined Products Eliminations Total 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 1,488 2,425 (602) (948) 5,312 8,241 336 493 — — 5,648 8,734 — — — — 6,636 10,253 — — — — 6,636 10,253 — — — — — — 1,179 1,060 — — 1,179 1,060 1,488 2,425 (602) (948) 11,948 18,494 1,515 1,553 — — 13,463 20,047 — — — — 981 1,495 — — — — 981 1,495 620 904 — — 4,073 6,318 — — — — 4,073 6,318 793 1,152 — — 3,245 5,056 — — — — 3,245 5,056 — — — — 560 745 — — — — 560 745 1,413 2,056 — — 8,859 13,614 — — — — 8,859 13,614 — — — — 308 640 — — — — 308 640 — — — — 1,500 2,197 — — — — 1,500 2,197 — — — — 82 167 336 493 — — 418 660 — — — — 101 168 152 182 — — 253 350 — — — — 153 162 1,026 875 — — 1,179 1,037 — — — — 2,144 3,334 1,514 1,550 — — 3,658 4,884 75 369 — — 1,547 2,494 1 3 — — 1,548 2,497 1,488 2,425 (602) (948) 11,948 18,494 1,515 1,553 — — 13,463 20,047

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2020
Disclosure of changes in accounting policies, accounting estimates and errors [Abstract]
Basis of Presentation	Basis of Presentation a) Basis of Measurement and Statement of Compliance The consolidated financial statements have been prepared by management on a historical cost basis with some exceptions, as detailed in the accounting policies set out below in accordance with International Financial Reporting Standards (“IFRS”), as issued by the International Accounting Standards Board (“IASB”). These accounting policies have been applied consistently for all periods presented in these consolidated financial statements. These consolidated financial statements were approved by the Board of Directors on February 8, 2021. Certain prior years’ amounts have been reclassified to conform with current presentation. b) Principles of Consolidation The consolidated financial statements include the accounts of Husky Energy Inc. and its subsidiaries. Subsidiaries are defined as any entities, including unincorporated entities such as partnerships, for which the Company has the power to govern their financial and operating policies to obtain benefits from their activities. The Company’s accounts reflect the proportionate share of the assets, liabilities, revenues, expenses and cash flows from the Company’s activities that are conducted jointly with third parties. Intercompany balances, net earnings and unrealized gains and losses arising from intercompany transactions are eliminated in preparing the consolidated financial statements. A portion of the Company’s activities relate to joint ventures (see Note 12), which are accounted for using the equity method. c) Use of Estimates, Judgments and Assumptions The timely preparation of the consolidated financial statements requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingencies, if any, as at the date of the financial statements and the reported amounts of revenue and expenses during the period. Actual results may differ from these estimates, judgments and assumptions. Estimates and underlying assumptions are reviewed on an ongoing basis. Revisions to accounting estimates are recognized in the period in which the estimates are revised and on a prospective basis. By their nature, estimates are subject to measurement uncertainty and changes in such estimates in future years could require a material change in the consolidated financial statements. These underlying assumptions are based on historical experience and other factors that management believes to be reasonable under the circumstances, and are subject to change as new events occur, as more industry experience is acquired, as additional information is obtained, and as the Company’s operating environment changes. Specifically, amounts recorded for depletion, depreciation, amortization and impairment, recoveries from insurance claims, asset retirement obligations, assets and liabilities measured at fair value, employee future benefits, income taxes and reserves and contingencies are based on estimates. Management makes judgments regarding the application of IFRS for each accounting policy. Critical judgments that have the most significant effect on the amounts recognized in the consolidated financial statements include determination of technical feasibility and commercial viability, impairment assessments, the determination of cash generating units (“CGUs”), changes in reserves estimates, the determination of a joint arrangement, the designation of the Company’s functional currency and the fair value of related party transactions. In early March 2020, the World Health Organization declared the COVID-19 coronavirus outbreak to be a pandemic. Responses to the spread of COVID-19 have resulted in significant disruption to business operations and a significant increase in economic uncertainty, with more volatile commodity prices and currency exchange rates, and a marked decline in long-term interest rates. Although economies are beginning to re-open, these events are resulting in a challenging economic climate in which it is difficult to reliably estimate the length or severity of these developments and their financial impact. The results of the potential economic downturn and any potential resulting direct and indirect impact to the Company has been considered in management’s estimates described above at the period end; however there could be a further prospective material impact in future periods. Significant estimates, judgments and assumptions made by management in the preparation of these consolidated financial statements are outlined in detail in Note 3. d) Functional and Presentation Currency The consolidated financial statements are presented in Canadian dollars, which is the Company’s functional currency. All financial information is presented in millions of Canadian dollars, except per share amounts and unless otherwise stated. The designation of the Company’s functional currency is a management judgment based on the currency of the primary economic environment in which the Company operates.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Disclosure of changes in accounting policies, accounting estimates and errors [Abstract]
Significant Account Policies	Significant Accounting Policies a) Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand less outstanding cheques and deposits with an original maturity of less than three months at the time of purchase. When outstanding cheques are in excess of cash on hand and short-term deposits, and the Company has the ability to net settle, the excess is reported in bank operating loans. Cash and cash equivalents held that are not available for use are classified as restricted cash. When restricted cash is not expected to be used within 12 months, it is classified as a non-current asset. b) Inventories Crude oil, natural gas, refined petroleum products and sulphur inventories are valued at the lower of cost or net realizable value. Cost is determined using average cost or on a first-in, first-out basis, as appropriate. Materials, parts and supplies are valued at the lower of average cost or net realizable value. Cost consists of raw material, labour, direct overhead, operating costs, transportation and depreciation, depletion and amortization. Commodity inventories held for trading purposes are carried at fair value and measured at fair value less costs to sell based on Level 2 observable inputs, refer to policy Note 3 (l). Any changes in commodity trading inventory fair value are included as gains or losses in Marketing and Other in the consolidated statements of loss during the period of change. Previous inventory impairment provisions are reversed when there is a change in the condition that caused the impairment and the inventory remains on hand. Unrealized intersegment net earnings on inventory sales are eliminated. c) Precious Metals The Company uses precious metals in conjunction with a catalyst as part of the downstream upgrading and refining processes. These precious metals remain intact; however, there is a loss during the reclamation process. The estimated loss is amortized to production and operating expenses over the period that the precious metal is in use, which is approximately two to five years. After the reclamation process, the actual loss is compared to the estimated loss and any difference is recognized in net loss. Precious metals are included in other assets on the balance sheet. d) Exploration and Evaluation Assets and Property, Plant and Equipment i) Cost Oil and gas properties and other property, plant and equipment are recorded at cost, including expenditures that are directly attributable to the purchase or development of an asset. Borrowing costs directly attributable to the acquisition, construction or production of a qualifying asset are included in the asset cost. Capitalization ceases when substantially all activities necessary to prepare the qualifying asset for its intended use are complete or when the construction and development of a project is suspended. ii) Exploration and Evaluation Costs The accounting treatment of costs incurred for oil and natural gas exploration, evaluation and development is determined by the classification of the underlying activities as either exploratory or developmental. The results from an exploration drilling program can take considerable time to analyze, and the determination that commercial reserves have been discovered requires determination of technical feasibility, commercial viability and industry experience. Exploration activities can fluctuate from year to year, due to such factors as the level of exploratory spending, the level of risk sharing with third parties participating in exploratory drilling and the degree of risk associated with drilling in particular areas. Properties that are assumed to be productive may, over a period of time, actually deliver oil and gas in quantities different than originally estimated because of changes in reservoir performance. Costs incurred after the legal right to explore an area has been obtained and before technical feasibility and commercial viability of the area have been established are capitalized as exploration and evaluation assets. These costs include costs to acquire acreage and exploration rights, legal and other professional fees and land brokerage fees. Pre-license costs and geological and geophysical costs associated with exploration activities are expensed in the period incurred. Costs directly associated with an exploration well are initially capitalized as an exploration and evaluation asset until the drilling of the well is complete and the results have been evaluated. If extractable hydrocarbons are found and are likely to be developed commercially, but are subject to further appraisal activity, which may include the drilling of wells, the costs continue to be carried as an exploration and evaluation asset while sufficient and continued progress is made in assessing the commercial viability of the hydrocarbons. Capitalized exploration and evaluation costs or assets are not depreciated and are carried forward until technical feasibility and commercial viability of the area is determined or the assets are determined to be impaired. Management determines technical feasibility and commercial viability when exploration and evaluation assets are reclassified to property, plant and equipment. This decision considers several factors, including the existence of reserves, establishing commercial and technical feasibility and whether the asset can be developed using a proved development concept and has received internal approval. Upon the determination of technical feasibility and commercial viability, capitalized exploration and evaluation assets are then transferred to property, plant and equipment. All such carried costs are subject to technical, commercial and management review, as well as review for impairment indicators, at least every reporting period to confirm the continued intent to develop or otherwise extract value from the discovery. These costs are also tested for impairment when transferred to property, plant and equipment. Capitalized exploration and evaluation expenditures related to wells that do not find reserves, or where no future activity is planned, are expensed as exploration and evaluation expenses. The application of the Company’s accounting policy for exploration and evaluation costs requires judgment in determining whether it is likely that future economic benefit exists when activities have not reached a stage where technical feasibility and commercial viability can be reasonably determined. Judgments may change as new information becomes available. iii) Development Costs Expenditures, including borrowing costs, on the construction, installation and completion of infrastructure facilities, such as platforms, pipelines and the drilling of development wells, are capitalized as oil and gas properties. Costs incurred to operate and maintain wells and equipment to lift oil and gas to the surface are expensed as production and operating expenses. iv) Other Property, Plant and Equipment Repair and maintenance costs, other than major turnaround costs, are expensed as incurred. Major turnaround costs are capitalized as part of property, plant and equipment when incurred and are amortized over the estimated period of time to the anticipated date of the next turnaround. v) Depletion, Depreciation and Amortization Oil and gas properties are depleted on a unit-of-production basis over the proved developed producing reserves of the particular field, except in the case of assets whose useful life is shorter or longer than the lifetime of the proved developed producing reserves of that field, in which case the straight-line method or a unit-of-production method based on total proved plus probable reserves is applied. The unit-of-production rate for the depletion of oil and gas properties related to total proved plus probable reserves takes into account expenditures incurred to date together with sanctioned future development expenditures required to develop the field. Oil and gas reserves are evaluated internally and audited by independent qualified reserve engineers. The estimation of reserves is an inherently complex process and involves the exercise of professional judgment. Estimates are based on projected future rates of production, estimated commodity prices, operating and royalty costs, engineering data and the estimated amount and timing of future expenditures, all of which are subject to uncertainty. Changes in reserve estimates can have an impact on reported net loss through revisions to depletion, depreciation and amortization expense, in addition to determining possible impairments and reversal of impairments of property, plant and equipment. Net reserves represent the Company's undivided gross working interest in total reserves after deducting crown, freehold and overriding royalty interests. Assumptions reflect market and regulatory conditions, as applicable, as at the balance sheet date and could differ significantly from other points in time throughout the year or future periods. Changes in market and regulatory conditions and assumptions can materially impact the estimation of net reserves. Depreciation for substantially all other property, plant and equipment is provided using the straight-line method based on the estimated useful lives of assets, which range from five to forty-five years. The useful lives of assets are estimated based upon the period the asset is expected to be available for use by the Company. Depletion, depreciation and amortization rates for all capitalized costs associated with the Company's activities are reviewed at least annually, or when events or conditions occur that impact capitalized costs, reserves and estimated service lives. e) Joint Arrangements Joint arrangements represent activities where the Company has joint control established by a contractual agreement. Joint control requires unanimous consent for financial and operational decisions. A joint arrangement is either a joint operation, whereby the parties have rights to the assets and obligations for the liabilities, or a joint venture, whereby the parties have rights to the net assets. For a joint operation, the consolidated financial statements include the Company’s proportionate share of the assets, liabilities, revenues, expenses and cash flows of the joint arrangement. The Company reports items of a similar nature to those on the financial statements of the joint arrangement, on a line-by-line basis, from the date that joint control commences until the date that joint control ceases. Joint ventures are accounted for using the equity method of accounting and recognized at cost and adjusted thereafter for the post-acquisition change in the Company’s share of the joint venture’s net assets. The Company’s consolidated financial statements include its share of the joint venture’s profit or loss and other comprehensive income (“OCI”) included in investment in joint ventures, until the date that joint control ceases. Classification of a joint arrangement as either joint operation or joint venture requires judgment. Management’s considerations include, but are not limited to, determining if the arrangement is structured through a separate vehicle and whether the legal form and contractual arrangements give the entity direct rights to the assets and obligations for the liabilities within the normal course of business. Other facts and circumstances are also assessed by management, including the entity’s rights to the economic benefits of assets and its involvement and responsibility for settling liabilities associated with the arrangement. f) Business Combinations Business combinations are accounted for using the acquisition method. Determining whether an acquisition meets the definition of a business combination or represents an asset purchase requires judgment on a case-by-case basis. If the acquisition meets the definition of a business combination, the assets and liabilities are recognized based on the contractual terms, economic conditions, the Company’s operating and accounting policies and other factors that exist on the acquisition date, which is the date on which control is transferred to the Company. The identifiable assets and liabilities are measured at their fair values on the acquisition date with limited exceptions. Any additional consideration payable, contingent upon the occurrence of a future event, is recognized at fair value on the acquisition date; subsequent changes in the fair value of the liability are recognized in net loss. Acquisition costs incurred are expensed and included in selling, general and administrative expenses in the consolidated statements of loss. g) Goodwill Goodwill is the excess of the purchase price paid over the recognized amount of net assets acquired through business combinations, which is inherently imprecise as judgment is required in the determination of the fair value of assets and liabilities. Goodwill, which is not amortized, is assigned to appropriate CGUs or groups of CGUs. Goodwill is tested for impairment annually and when circumstances indicate that the carrying value may be impaired. Impairment losses are recognized in net loss and are not subject to reversal. On the disposal or termination of a previously acquired business, any remaining balance of associated goodwill is included in the determination of the gain or loss on disposal. h) Impairment and Reversals of Impairment on Non-Financial Assets The carrying amounts of the Company’s non-financial assets, other than inventories and deferred tax assets but including right-of-use assets, are reviewed at the end of each reporting period to determine whether there is an indication of impairment or reversal of previously recorded impairment. If such indication exists, the recoverable amount is estimated. Determining whether there are any indications of impairment or impairment reversals requires significant judgment of external factors, such as an extended change in prices or margins for oil and gas commodities or refined products, a significant change in an asset’s market value, a significant revision of estimated volumes, revision of future development costs, a change in the entity’s market capitalization or significant changes in the technological, market, economic or legal environment that would have an impact on the Company’s CGUs. If any indication of impairment or impairment reversals exist, an estimate of the asset’s recoverable amount is calculated as the higher of the fair value less costs to sell (“FVLCS”) and the asset’s value in use (“VIU”) for an individual asset or CGU. If the asset does not generate cash inflows that are largely independent of those from other assets or groups of assets, the asset is tested as part of a CGU, which is the smallest identifiable group of assets, liabilities and associated goodwill that generates cash inflows that are largely independent of the cash inflows from other assets or groups of assets. Determination of the Company’s CGUs is subject to management’s judgment. FVLCS is the amount that would be obtained from the sale of a CGU in an arm’s length transaction between knowledgeable and willing parties. The FVLCS is generally determined as the net present value of the estimated future cash flows expected to arise from a CGU, including any expansion prospects, and its eventual disposal, using assumptions that an independent market participant may take into account. These cash flows are discounted using a rate that would be applied by a market participant to arrive at a net present value of the CGU, less cost to dispose. VIU is the net present value of the estimated future cash flows expected to arise from the continued use of the asset in its present form and its eventual disposal. VIU is determined by applying assumptions specific to the Company’s continued use and can only take into account sanctioned future development costs. Estimates of future cash flows used in the evaluation of impairment of assets are made using management’s forecasts of commodity prices, royalty rates, operating costs and future capital expenditures, forecasted crack spreads, growth rate, discount rate and, in the case of oil and gas properties, expected production volumes. Expected production volumes take into account assessments of field reservoir performance and include expectations about proved and probable volumes and where applicable economically recoverable resources associated with interests in certain Husky properties which are risk-weighted utilizing geological, production, recovery, market price and economic projections. Either the cash flow estimates or the discount rate is risk-adjusted to reflect local conditions as appropriate. Given that the calculations for recoverable amounts require the use of estimates and assumptions, including forecasts of commodity prices, marketing supply and demand, product margins and in the case of oil and gas properties, expected production volumes, it is possible that the assumptions may change, which may impact the estimated life of the CGU and may require a material adjustment to the carrying value of goodwill and non-financial assets. An impairment loss is recognized if the carrying amount of an asset or its CGU exceeds its estimated recoverable amount. Impairment losses recognized with respect to CGUs are allocated first to reduce the carrying amount of any goodwill allocated to the units and then to reduce the carrying amounts of the other assets in the CGU or group of CGUs on a pro rata basis. Impairment losses are recognized in depletion, depreciation, amortization and impairment in the consolidated statements of loss. Impairment losses recognized in prior years are assessed at the end of each reporting period for indications that the impairment has decreased or no longer exists. An impairment loss is reversed only to the extent that the carrying amount of the asset or CGU does not exceed the carrying amount that would have been determined, net of depletion, depreciation and amortization, if no impairment loss had been recognized. i) Asset Retirement Obligations (“ARO”) A liability is recognized for future legal or constructive retirement obligations associated with the Company’s assets. The Company has significant obligations to remove tangible assets and restore land after operations cease and the Company retires or relinquishes the asset. The retirement of Upstream and Downstream assets consists primarily of plugging and abandoning wells, abandoning surface and subsea plant and equipment and facilities and restoring land to a state required by regulation or contract. The amount recognized is the net present value of the estimated future expenditures determined in accordance with local conditions, current technology and current regulatory requirements. The obligation is calculated using the current estimated costs to retire the asset inflated to the estimated retirement date and then discounted using a credit-adjusted risk-free discount rate. The liability is recorded in the period in which an obligation arises with a corresponding increase to the carrying value of the related asset. The liability is progressively accreted over time as the effect of discounting unwinds, creating an expense recognized in finance expenses. The costs capitalized to the related assets are amortized in a manner consistent with the depletion, depreciation and amortization of the underlying assets. Actual retirement expenditures are charged against the accumulated liability as incurred. Liabilities for ARO are adjusted every reporting period for changes in estimates. These adjustments are accounted for as a change in the corresponding capitalized cost, except where a reduction in the provision is greater than the undepreciated capitalized cost of the related assets, in which case the capitalized cost is reduced to nil and the remaining adjustment is recognized in net loss. Changes to the amount of capitalized costs will result in an adjustment to future depletion, depreciation and amortization, and to finance expenses. Estimating the ARO requires significant judgment as restoration technologies and costs are constantly changing, as are regulatory, political, environmental and safety considerations. Inherent in the calculation of the ARO are numerous assumptions including the ultimate settlement amounts, future third-party pricing, inflation factors, risk-free discount rates, credit risk, timing of settlement and changes in the legal, regulatory, environmental and political environments. Future revisions to these assumptions may result in material changes to the ARO liability. Adjustments to the estimated amounts and timing of future ARO cash flows are a regular occurrence in light of the significant judgments and estimates involved. j) Legal and Other Contingent Matters Provisions and liabilities for legal and other contingent matters are recognized in the period when the circumstance becomes probable that a future cash outflow resulting from past operations or events will occur and the amount of the cash outflow can be reasonably estimated. The timing of recognition and measurement of the provision requires the application of judgment to existing facts and circumstances, which can be subject to change, and the carrying amounts of provisions and liabilities are reviewed regularly and adjusted accordingly. The Company is required to both determine whether a loss is probable based on judgment and interpretation of laws and regulations, and determine that the loss can be reasonably estimated. When a loss is recognized, it is charged to net loss. The Company continually monitors known and potential contingent matters and makes appropriate disclosure and provisions when warranted by the circumstances present. k) Share Capital Preferred shares are classified as equity since they are cancellable and redeemable only at the Company’s option and dividends are discretionary and payable only if declared by the Board of Directors. Incremental costs directly attributable to the issuance of shares and stock options are recognized as a deduction from equity, net of tax. Common share dividends are paid out in common shares, or in cash, and preferred share dividends are paid in cash. Both common and preferred share dividends are recognized as distributions within equity. l) Financial Instruments Financial instruments are any contracts that give rise to a financial asset of one entity and a financial liability or equity instrument of another entity. Financial assets are classified in one of the following categories: subsequently measured at amortized cost, fair value through other comprehensive income (“FVTOCI”), or fair value through profit or loss (“FVTPL”). Financial liabilities are initially recognized at fair value, and subsequently measured based on classification in one of the following categories: subsequently measured at amortized cost and FVTPL. Financial assets and liabilities are not offset unless there is a currently enforceable legal right to offset the recognized amounts and there is an intention to settle on a net basis, to realize the assets and settle the liabilities simultaneously. Financial assets and liabilities subsequently measured at amortized costs are measured using the effective interest method. The effective interest method is a method of calculating the amortized costs of a financial liability and of allocating interest expense over the relevant period. Transaction costs that are directly attributable to the acquisition or issue of a financial instrument are measured at amortized cost and added to the fair value initially recognized. Financial instruments at FVTPL are stated at fair value, with any gains or losses arising on remeasurement recognized in profit or loss. Unrealized gains and losses on FVTPL financial instruments related to trading activities are recognized in marketing and other in the consolidated statements of loss, and unrealized gains and losses on all other FVTPL financial instruments are recognized in other - net. Transaction costs directly attributable to the acquisition of financial assets or liabilities at FVTPL are recognized immediately in net loss. Financial instruments at FVTOCI are stated at fair value, with any gains or losses arising on remeasurement recognized in OCI except for impairment gains or losses and foreign exchange gains and losses. Financial instruments subsequently revalued at fair value are further categorized using a three-level hierarchy that reflects the significance of the inputs used in determining fair value. Level 1 fair value is determined by reference to quoted prices in active markets for identical assets and liabilities. Level 2 fair value is based on inputs that are independently observable for similar assets or liabilities. Level 3 fair value is not based on independently observable market data. The disclosure of the fair value hierarchy excludes financial assets and liabilities where book value approximates fair value. A financial asset is derecognized when the contractual rights to the cash flows from the financial asset have expired, or it transfers the contractual rights to receive the cash flows of the financial assets and the Company has transferred substantially all the risks and rewards of ownership of the financial asset. A financial liability is derecognized when the liability is extinguished, discharged, cancelled or expires. m) Derivative Instruments and Hedging Activities Derivatives are financial instruments for which the fair value changes in response to market risks, require little or no initial investment and are settled at a future date. Derivative instruments are utilized by the Company to manage various market risks including volatility in commodity prices, foreign exchange rates and interest rate exposures. The Company’s policy is not to utilize derivative instruments for speculative purposes. The Company may enter into swap and other derivative transactions to hedge or mitigate the Company’s commercial risk, including derivatives that reduce risks that arise in the ordinary course of the Company’s business. The Company may choose to apply hedge accounting to derivative instruments. The fair values of derivatives are determined using valuation models that require assumptions concerning the amount and timing of future cash flows and discount rates. These estimates are also subject to change with fluctuations in commodity prices, interest rates, foreign currency exchange rates and estimates of non-performance. When able, the Company will determine fair value by incorporating forward market prices and rates that are compared to quotes received from financial institutions to ensure reasonability. The actual settlement of a derivative instrument could differ materially from the fair value recorded and could impact future results. i) Derivative Instruments All derivative instruments, other than those designated as effective hedging instruments or certain non-financial derivative contracts that meet the Company’s own use requirements, are classified as FVTPL and are recorded at fair value. Gains and losses on these instruments are recorded in the consolidated statements of loss in the period they occur. The Company may enter into commodity price contracts in order to offset fixed or floating prices with market rates to manage exposures to fluctuations in commodity prices. The estimation of the fair value of commodity derivatives incorporates forward prices and adjustments for quality or location. The related inventory is measured at fair value based on exit prices. Gains and losses from these derivative contracts, which are not designated as effective hedging instruments, are recognized in revenues or purchases of crude oil and products and are initially recorded at settlement date. Derivative instruments that have been designated as effective hedging instruments are further classified as either fair value or cash flow hedges (see “Hedging Activities”). ii) Embedded Derivatives Derivatives embedded within a hybrid contract containing a financial asset host are not accounted for separately, rather the whole instrument is classified as FVTPL. Derivatives embedded in other hybrid contracts are recorded separately when the economic characteristics and risks of the embedded derivative are not clearly and closely related to those of the host contract and the host contract is not measured at FVTPL. The definition of an embedded derivative is the same as freestanding derivatives. Embedded derivatives are measured at fair value with gains and losses recognized in net loss. iii) Hedging Activities At the inception of a derivative transaction, if the Company elects to use hedge accounting, formal designation and documentation is required. The documentation must include: identification of the hedged item or transaction, the hedging instrument, the nature of the risk being hedged, the Company’s risk management objective and strategy for undertaking the hedge and how the Company will assess the hedging instrument’s effectiveness in offsetting the exposure to changes in the hedged item. A hedge is assessed at inception and at the end of each reporting period to ensure that it is highly effective in offsetting changes in fair values or cash flows of the hedged item. For a fair value hedge, the gain or loss from remeasuring the hedging instrument at fair value is recognized immediately in net loss with the offsetting gain or loss on the hedged item. When fair value hedge accounting is discontinued, the carrying amount of the hedging instrument is deferred and amortized to net loss over the remaining maturity of the hedged item. For a cash flow hedge, the effective portion of the gain or loss is recorded in OCI. Any hedge or portion of a hedge that is ineffective is immediately recognized in net loss. Hedge accounting is discontinued on a prospective basis when the hedging relationship no longer qualifies for hedge accounting. Any gain or loss on the hedging instrument resulting from the discontinuation of a cash flow hedge is deferred in OCI until the forecasted transaction date. If the forecasted transaction date is no longer expected to occur, the gain or loss is recognized in net loss in the period of discontinuation. A net investment hedge of a foreign operation is accounted for similarly to a cash flow hedge. The Company may designate certain U.S. dollar denominated debt as a hedge of its net investment in foreign operations for which the U.S. dollar is the functional currency. The unrealized foreign exchange gains and losses arising from the translation of the debt are recorded in OCI, net of tax, and are limited to the translation gain or loss on the net investment. n) Comprehensive Loss Comprehensive loss consists of net loss and OCI. OCI is comprised of the change in the fair value of the effective portion of the derivatives used as hedging items in a cash flow hedge or net investment hedge, the exchange gains and losses arising from the translation of foreign operations with a functional currency that is not Canadian dollars and the actuarial gains and losses on defined benefit pension plans. Amounts included in OCI are shown net of tax. Other reserves is an equity category comprised of the cumulative amounts of OCI, relating to foreign currency translation and hedging. o) Impairment of Financial Assets A financial asset is assessed at the end of each reporting period to determine whether it is impaired, based on objective evidence indicating that one or more events have had a negative effect on the estimated future cash flows of that asset. Objective evidence used by the Company to assess impairment of financial assets includes quoted market prices for similar financial assets and historical collection rates. An impairment loss with respect to a financial asset measured at amortized cost is calculated as the difference between its carrying amount and the net present value of the estimated future cash flows discounted at the original effective interest rate, according to the expected credit loss model. Significant financial assets are tested for impairment on an individual basis. The remaining financial assets are assessed for lifetime expected credit losses collectively in groups that share similar credit risk characteristics. All impairment losses are recognized in net loss. An impairment loss is reversed if the reversal can be related objectively to an event occurring after the impairment loss was recognized. Given that the calculations for the net present value of estimated future cash flows related to derivative financial assets require the use of estimate
Description of accounting policy for dividends [text block]	Share CapitalPreferred shares are classified as equity since they are cancellable and redeemable only at the Company’s option and dividends are discretionary and payable only if declared by the Board of Directors. Incremental costs directly attributable to the issuance of shares and stock options are recognized as a deduction from equity, net of tax. Common share dividends are paid out in common shares, or in cash, and preferred share dividends are paid in cash. Both common and preferred share dividends are recognized as distributions within equity.
Description of accounting policy for leases [text block]	Leases Contractual arrangements, which signify a right to control the use of an identified asset for a period of time are considered leases. Each contractual arrangement is assessed to determine if the Company obtains substantially all the economic benefit from use of the identified asset. Leases for which the Company is a lessee are capitalized at the earlier of commencement of the lease term or when the asset becomes available for use, at the present value of the lease payments applying the implicit interest rate, if readily determined, or the Company’s incremental borrowing rate. Adjustments to the lease asset are made if the contractual arrangement includes costs to dismantle the asset or any incentives received. Generally, lease components are considered in the present value calculation, with non-lease components expensed as incurred. Leased assets are depreciated over the shorter of the estimated useful life of the asset or the lease term. The lease liability is remeasured when there is a change in future lease payments arising from a change in rate, if there is a change to the Company’s expected residual value guarantee payable, or if there are changes in the assessment for exercising a purchase, termination or extension option. If this occurs, a corresponding adjustment to the carrying value of the right-of-use asset is completed. If the carrying amount of the right-of-use asset has already been reduced to zero, the adjustment is recognized in net loss. The Company applies the recognition exemption for short-term leases 12 months or less in length, and leases for which the underlying asset is of low value. The expenses for these leases are recognized systematically over the lease term in either production, operating and transportation expense, purchases of crude oil and products or selling, general and administrative expenses. i) Nature of Leasing Activities Oil and Gas Properties The Company leases offshore vessels and associated equipment for use in developing reserves on oil and gas properties. These leases vary in length and, in certain cases, expenses incurred are allocated to the carrying value of other assets in property, plant and equipment. Additionally, the Company leases land, buildings and equipment for sustainment of the Company’s upstream oil and gas operations. Processing Transportation and Storage The Company leases tanks with dedicated storage capacity at terminals or facilities while transporting various oil and gas products. The Company also records leases for any pipelines where the Company has a right to substantially all the economic benefits. The terms of these leases vary depending on capacity constraints by third parties and negotiations of take-or-pay arrangements. The Company also employs rail transportation, where the Company leases dedicated rail cars. Upgrading The Company does not have any significant leasing arrangements in the upgrading asset class. Refining The Company leases supply facilities and pipelines for products used in the refining process when the Company has the right to substantially all the capacity of the asset. The Company also uses rail transportation, where it enters into arrangements for dedicated rail cars. Retail and Other

Cash and Cash Equivalents

Cash and Cash Equivalents	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents at December 31, 2020 included $709 million of cash (December 31, 2019 – $327 million) and $26 million of short-term investments with original maturities less than three months at the time of purchase (December 31, 2019 – $1,448 million).

Accounts Receivable

Accounts Receivable	12 Months Ended
	Dec. 31, 2020
Term Classification [Table]
Accounts Receivable	Accounts Receivable Accounts Receivable ($ millions) December 31, 2020 December 31, 2019 Trade receivables 773 1,327 Provision for expected credit losses (36) (34) Derivatives due within one year 33 38 Other (1) 349 168 End of year 1,119 1,499 (1) Includes insurance proceeds of $312 million (2019 - $114 million), related to the Superior Refinery incident.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Inventories	Inventories Inventories ($ millions) December 31, 2020 December 31, 2019 Crude oil, natural gas and NGL 409 627 Refined petroleum products 411 553 Trading inventories measured at fair value less costs to sell 121 155 Materials, supplies and other 174 151 End of year 1,115 1,486 Impairment of inventory to net realizable value for the year ended December 31, 2020 was $7 million (December 31, 2019 – $15 million), as a result of declining market benchmark prices.

Restricted Cash

Restricted Cash	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Restricted Cash	Restricted Cash In accordance with the provisions of the regulations of the People’s Republic of China, the Company is required to deposit funds into separate accounts restricted to the funding of future asset retirement obligations in offshore China. As at December 31, 2020, the Company had deposited funds of $164 million

Exploration and Evaluation Cost

Exploration and Evaluation Costs	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Exploration and Evaluation Costs	Exploration and Evaluation Assets Exploration and Evaluation Assets ($ millions) 2020 2019 Beginning of year 643 997 Additions 1 46 Transfers to property, plant and equipment ( note 9 ) (3) (44) Expensed exploration expenditures previously capitalized (594) (355) Exchange adjustments (1) (1) End of year 46 643 During 2020, $439 million and $150 million (2019 - $331 million due primarily to Offshore and Western Canada Production) of the expensed exploration expenditures previously capitalized related to write-downs within the Offshore and Lloydminster Heavy Oil Value Chain business segments, respectively. The write-downs were primarily due to changes in management's future development plans resulting from the sustained decline in forecasted crude oil prices. The following exploration and evaluation expenses for the years ended December 31, 2020 and 2019 relate to activities associated with the exploration for and evaluation of crude oil and natural gas resources and were recorded in the Integrated Corridor and Offshore business segments. Exploration and Evaluation Expense Summary (1) ($ millions) 2020 2019 Seismic, geological and geophysical 117 131 Expensed drilling 612 409 Expensed land 4 7 733 547 (1) Includes expensed exploration expenditures previously capitalized.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Property, Plant and Equipment	Property, Plant and Equipment Property, Plant and Equipment Oil and Gas Properties Processing, Upgrading Refining Retail and Other Total ($ millions) Cost December 31, 2018 44,196 101 2,659 10,691 3,095 60,742 Transfers to right-of-use assets (1) (note 10) (336) — — (180) — (516) Additions 2,340 2 58 899 160 3,459 Acquisitions 10 — — — — 10 Transfers from exploration and evaluation (note 8) 44 — — — — 44 Transfers from right-of-use assets (2) (note 10) 101 — — — — 101 Intersegment transfers 2 — — 27 (29) — Changes in asset retirement obligations (note 18) 469 1 5 19 23 517 Disposals and derecognition (16) (2) (1) (943) (2) (964) Exchange adjustments (223) (1) — (496) (2) (722) December 31, 2019 46,587 101 2,721 10,017 3,245 62,671 Additions 852 — 216 502 70 1,640 Acquisitions 1 — — — — 1 Transfers from exploration and evaluation (note 8) 3 — — — — 3 Transfers from right-of-use assets (2) (note 10) 4 — — — — 4 Intersegment transfers 18 41 — — (59) — Changes in asset retirement obligations (note 18) (530) — (13) (51) (33) (627) Disposals and derecognition (419) (2) — (12) (2) (435) Exchange adjustments (80) (3) — 64 (1) (20) December 31, 2020 46,436 137 2,924 10,520 3,220 63,237 Accumulated depletion, depreciation, amortization and impairment December 31, 2018 (27,379) (50) (1,585) (3,933) (1,995) (34,942) Transfers to right-of-use assets (1) (note 10) 12 — — 40 — 52 Depletion, depreciation, amortization and impairment (4,082) (2) (115) (736) (239) (5,174) Intersegment transfers — — — (17) 17 — Disposals and derecognition 8 — — 724 2 734 Exchange adjustments 93 1 — 187 1 282 December 31, 2019 (31,348) (51) (1,700) (3,735) (2,214) (39,048) Depletion, depreciation, amortization and impairment (7,083) (46) (90) (3,644) (228) (11,091) Intersegment transfers (9) — — — 9 — Disposals and derecognition 380 12 — — 1 393 Exchange adjustments 47 1 — (44) 1 5 December 31, 2020 (38,013) (84) (1,790) (7,423) (2,431) (49,741) Net book value December 31, 2019 15,239 50 1,021 6,282 1,031 23,623 December 31, 2020 8,423 53 1,134 3,097 789 13,496 (1) Transfer to right-of-use assets due to the adoption of IFRS 16 on January 1, 2019. (2) Includes capitalized depreciation from right-of-use assets. Costs of property, plant and equipment, including major development projects, not subject to depletion, depreciation and amortization as at December 31, 2020 were $2.0 billion (December 31, 2019 – $6.8 billion) including undeveloped land assets of $118 million as at December 31, 2020 (December 31, 2019 – $127 million). Included in depletion, depreciation, amortization and impairment expenses for the year ended December 31, 2020 is a pre-tax impairment charge of $8,945 million on Oil and Gas Properties located at Lloydminster Heavy Oil Value Chain, Oil Sands and Western Canada within the Integrated Corridor business segment, the White Rose and Terra Nova CGUs within the Offshore business segment and Refining assets located in the U.S. Refining CGUs within the Integrated Corridor business segment (year ended December 31, 2019 - $2,584 million on CGUs located at Oil Sands, Western Canada, and US Refining within the Integrated Corridor business segment and the White Rose CGU within the Offshore business segment). The impairment charge was primarily the result of the market impact from the COVID-19 pandemic, which has resulted in declines in forecasted long-term commodity prices, refinery crack spread, reduced capital investment, management’s decision to delay capital investment in the White Rose CGU and considered market indicators including the strategic combination with Cenovus Energy Inc. The recoverable amount of the impaired CGUs was estimated based on fair value less costs to sell methodology using estimated after-tax discounted cash flows on proved plus probable reserves for the Lloydminster Heavy Oil Value Chain, Sunrise, Western Canada and Offshore CGUs and after-tax discounted cash flows based on forecasted crack spreads for refining CGUs (Level 3). The Company used an after-tax discount rate of 12% (2019 - 10%) (Level 3). The following table summarizes impairment for each CGU within the Integrated Corridor business segment for the year ended December 31, 2020: CGU ($ millions) Allocated to PP&E Allocated to right-of-use assets (note 10) Allocated to Goodwill (note 11) Allocated to Joint Arrangements (note 12) Total impairment recorded Lloydminster Heavy Oil & Gas 270 1 — — 271 Tucker 271 — — — 271 Minnedosa Ethanol Plant 42 — — — 42 Lloydminster Ethanol Plant 57 3 — — 60 Husky Midstream Limited Partnership — — — 606 606 Lloyd Heavy Oil Value Chain CGUs total 640 4 — 606 1,250 Northern 517 2 — — 519 Rainbow 119 — — — 119 Western Canada CGUs total 636 2 — — 638 Lima Refinery 1,203 50 669 — 1,922 BP-Husky Toledo Refinery 1,662 6 — — 1,668 Superior Refinery 366 — — — 366 U.S. Refining CGUs total 3,231 56 669 — 3,956 Sunrise CGU 1,428 255 — — 1,683 Total 5,935 317 669 606 7,527 The following table summarizes impairment for each CGU within the Offshore business segment for the year ended December 31, 2020: CGU ($ millions) Allocated to PP&E Allocated to right-of-use assets (note 10) Total impairment recorded White Rose 2,760 94 2,854 Terra Nova 250 — 250 Total 3,010 94 3,104 The recoverable amount of the impaired CGUs with Oil and Gas Properties, at December 31, 2020, and U.S. Refining CGUs, at September 30, 2020, was $6,204 million. The recoverable amounts are sensitive to commodity prices, crack spreads, discount rate, production volumes, royalties, operating costs and future capital expenditures. Commodity prices and crack spreads are based on market indicators at the end of the period. Management’s long-term assumptions are benchmarked against forward price curves and pricing forecasts prepared by external firms. The table below summarizes the forecasted prices used in determining the recoverable amounts: WTI Brent Edmonton Light AECO Chicago 3:2:1 Crack Spread ($US/bbl) (1) Foreign Exchange 2021 47.17 49.42 55.76 2.78 12.00 0.77 2022 50.17 52.85 59.89 2.70 14.00 0.77 2023 53.17 56.04 63.48 2.61 14.00 0.76 2024 54.97 57.87 65.76 2.65 16.00 0.76 2025 ( 2) 56.07 59.00 67.13 2.70 16.00 0.76 (1) Prices are based on September 30, 2020 assessment of U.S. Refining CGUs. (2) Prices are escalated at 2% thereafter. The discount rate for FVLCS represents the rate a market participant would apply to the cash flows in a market transaction. The discount rate is derived from the Company's post-tax weighted average cost of capital with appropriate adjustments made to reflect the risks specific to the CGUs. Production volumes, throughput, operating costs, royalties and future capital expenditures are based on management’s best estimates. A change in the discount rate or forward price curve over the life of the reserves and refineries will result in the following impact on the impaired CGUs: Discount Rate Commodity Price ($ millions) 1% Increase in Discount Rate 1% Decrease in Discount Rate 5% Increase in Forward Price 5% Decrease in Forward Price Total impairment - Increase (Decrease) 599 (687) (1,511) 1,530
Sensitivity analysis for types of market risk [text block]	Discount Rate Commodity Price ($ millions) 1% Increase in Discount Rate 1% Decrease in Discount Rate 5% Increase in Forward Price 5% Decrease in Forward Price Total impairment - Increase (Decrease) 599 (687) (1,511) 1,530

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Disclosure of leases [text block]	Note 10 Right-of-use Assets and Lease Liabilities Right-of-use Assets Oil and Gas Properties Processing, Upgrading Refining Retail and Other Total ($ millions) January 1, 2019 Transfers from property, plant and equipment (note 9) 324 — — 140 — 464 Initial recognition 721 100 — 70 412 1,303 1,045 100 — 210 412 1,767 Additions 1 — — 80 5 86 Transfers to property, plant and equipment (note 9) (101) — — — — (101) Disposals and derecognition (11) — — (31) 2 (40) Revaluation (194) 1 — (1) 8 (186) Depreciation and impairment (222) (11) — (50) (39) (322) Other 2 — — (4) — (2) December 31, 2019 520 90 — 204 388 1,202 Additions 5 6 — 15 4 30 Transfers to property, plant and equipment (note 9) (4) — — — — (4) Disposals and derecognition (3) — — — — (3) Revaluation — 16 — 11 — 27 Depreciation and impairment (399) (11) — (91) (53) (554) Other 1 (1) — — — — December 31, 2020 120 100 — 139 339 698 During the year ended December 31, 2020, a pre-tax impairment charge of $411 million (year ended December 31, 2019 - $165 million) on right-of-use assets was recorded on the Lloydminster Heavy Oil Value Chain, Sunrise, Western Canada and U.S. Refining CGUs within the Integrated Corridor and White Rose CGU within Offshore business segments. Refer to Note 9. Lease Liabilities Balance Sheets ($ millions) December 31, 2020 December 31, 2019 Current lease liabilities 102 109 Non-current lease liabilities 1,298 1,353 Maturity Analysis Within 1 year After 1 year but no more than 5 years More than 5 years Total ($ millions) 2020 2019 2020 2019 2020 2019 2020 2019 Future lease payments 195 205 643 653 2,031 2,174 2,869 3,032 Interest 93 96 337 352 1,039 1,122 1,469 1,570 Present value of lease payments 102 109 306 301 992 1,052 1,400 1,462 Results of Operations ($ millions) December 31, 2020 December 31, 2019 Interest expense on lease liabilities (note 22) 97 106 Expenses relating to short-term leases 13 18 Cash Flow Summary ($ millions) December 31, 2020 December 31, 2019 Total cash flow used for leases 208 339

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Goodwill	Goodwill Goodwill ($ millions) December 31, 2020 December 31, 2019 Beginning of year (1) 656 690 Exchange adjustments 13 (34) Impairment (note 9) (669) — End of year — 656 (1) Goodwill relates to the Lima Refinery. During the year ended December 31, 2020, the Company determined the carrying amount of the Lima Refinery CGU in the U.S. Refining segment exceeded its recoverable amount and the impairment was attributable to goodwill and physical refining assets. A pre-tax goodwill impairment charge of $669 million was included in depletion, depreciation, amortization and impairment expense for the year ended December 31, 2020. The recoverable amount of goodwill was $nil as at September 30, 2020 and estimated using the FVLCS methodology based on cash flows expected over a 50-year period and an after-tax discount rate of 12% (2019 - 9%). Management used the FVLCS calculation for the Lima Refinery CGU, which is sensitive to changes in discount rate, forecasted crack spread and future capital expenditures. The discount rate is derived from the after-tax weighted average cost of capital, with appropriate adjustments made to reflect the risks specific to the Lima refinery.

Joint Arrangements

Joint Arrangements	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Joint Arrangements	Joint Arrangements Joint Operations BP-Husky Refining LLC The Company holds a 50% ownership interest in BP-Husky Refining LLC, which owns and operates the BP-Husky Toledo Refinery in Ohio. Sunrise Oil Sands Partnership The Company holds a 50% interest in the Sunrise Oil Sands Partnership, which is engaged in operating an oil sands project in Northern Alberta. Joint Venture Husky-CNOOC Madura Ltd. The Company holds 40% joint control in Husky-CNOOC Madura Ltd., which is engaged in the exploration for and production of oil and gas resources in Indonesia. Results of the joint venture are included in the consolidated statements of loss in the Offshore business segment. Summarized below is the financial information for Husky-CNOOC Madura Ltd. accounted for using the equity method: Results of Operations ($ millions, except share of equity investment) 2020 2019 Revenues 386 424 Expenses (280) (267) Net earnings 106 157 Share of equity investment 40 % 40 % Proportionate share of equity investment 39 50 Balance Sheets ($ millions, except share of equity investment) December 31, 2020 December 31, 2019 Current assets (1) 215 208 Non-current assets 1,657 1,840 Current liabilities (77) (70) Non-current liabilities (2) (1,160) (1,427) Net assets 635 551 Share of net assets 40 % 40 % Carrying amount in balance sheet 457 516 (1) Includes cash and cash equivalents of $48 million (2019 – $42 million). (2) Includes deferred revenue of $8 million (2019 - $nil) related to take-or-pay commitments, with respect to natural gas production volumes from the BD Project, not taken by the purchaser. As per the terms of the agreement, the purchaser has until the end of the agreement to take these volumes. The Company’s share of equity investment and carrying amount of share of net assets does not equal the 40% joint control of the expenses and net assets of Husky-CNOOC Madura Ltd. due to differences in the accounting policies of the joint venture and the Company and non-current liabilities of the joint venture which are not included in the Company’s carrying amount of net assets due to equity accounting. Husky Midstream Limited Partnership The Company holds a 35% interest in HMLP, which owns midstream assets in Alberta and Saskatchewan. The assets are held by HMLP, of which Husky owns 35%, Power Assets Holdings Ltd. (“PAH”) owns 48.75% and CK Infrastructure Holdings Ltd. (“CKI”) owns 16.25%. Results of the joint venture are included in the consolidated statements of loss in Lloydminster Heavy Oil Value Chain in the Integrated Corridor business segment. Summarized below is the financial information for HMLP accounted for using the equity method: Results of Operations ($ millions, except share of equity investment) 2020 2019 Revenues 322 316 Expenses (206) (228) Net earnings 116 88 Share of equity investment 35 % 35 % Proportionate share of equity investment (1) (32) 9 (1) As at December 31, 2020, the Company’s share of pre-tax losses relating to its investment in HMLP were $7 million (2019 – $nil) which were unrecognized as a result of the investment being fully written off in the third quarter of 2020. Balance Sheet ($ millions, except share of net assets) December 31, 2020 December 31, 2019 Current assets (1) 108 171 Non-current assets 3,075 3,031 Current liabilities (30) (163) Non-current liabilities (1,175) (1,059) Net assets 1,978 1,980 Share of net assets 35 % 35 % Carrying amount in balance sheet — 666 (1) Current assets include cash and cash equivalents of $30 million (2019 – $86 million). The Company’s share of equity investment and carrying amount of share of net assets does not equal the 35% joint control of the net income and net assets of HMLP due to the potential fluctuation in the partnership profit structure. During the year ended December 31, 2020, the Company determined the carrying amount of the investment in the HMLP joint venture in the Integrated Corridor segment exceeded its recoverable amount and the amount of impairment was attributable to the Company’s carrying amount of the investment. A pre-tax impairment charge of $606 million was included in depletion, depreciation, amortization and impairment expense for the year ended December 31, 2020. The recoverable amount was $nil as at September 30, 2020, the date of the impairment test, and was estimated using the FVLCS methodology based on cash flows expected over a 40-year period and an after-tax discount rate of 12% (Level 3). The impairment charge was a result of sustained declines in forecasted short and long-term cash distributions. Management used the FVLCS calculation for the investment in HMLP, which is sensitive to changes in the Company’s share of net income and net assets in HMLP as a result of the partnership profit structure, future capital expenditures from the investment and discount rate. The discount rate is derived from the Company’s post-tax weighted average cost of capital, with appropriate adjustments made to reflect the risks specific to the investment. Throughput volumes, cash distributions and future capital expenditures are based on management’s best estimates.

Other Assets

Other Assets	12 Months Ended
	Dec. 31, 2020
Miscellaneous non-current assets [abstract]
Other Assets	Other Assets Other Assets ($ millions) December 31, 2020 December 31, 2019 Long-term receivables (1) 130 489 Precious metals 21 22 Other 15 13 End of year 166 524 (1) Includes insurance proceeds o f $98 million ( 2019 – $435 million), related to the Superior Refinery incident. For the year ended December 31, 2020, the Company accrued pre-tax recoveries for rebuild costs, incident costs and business interruption associated with the Superior Refinery incident of $85 million (December 31, 2019 - $630 million), which is included in other-net in the consolidated statements of loss.

Bank Operating Loans

Bank Operating Loans	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Bank Operating Loans	Bank Operating Loans At December 31, 2020, the Company had unsecured short-term borrowing lines of credit with banks totaling $975 million (1) (December 31, 2019 – $900 million) and letters of credit under these lines of credit totaling $427 million (December 31, 2019 – $436 million). As at December 31, 2020, bank operating loans were $40 million (December 31, 2019 – $nil). Interest payable is based on Bankers’ Acceptance, CAD Prime Rate, U.S. LIBOR, or U.S. Base Rates. Sunrise Oil Sands Partnership has an unsecured demand credit facility of $10 million (December 31, 2019 – $10 million) available for general purposes. The Company’s proportionate share of the credit facility is $5 million (December 31, 2019 – $5 million). As at December 31, 2020, there was no balance outstanding under this credit facility (December 31, 2019 – no balance). (1) Includes $125 million demand facilities available specifically for letters of credit only. The Company had the following available credit facilities as at December 31, 2020: Credit Facilities ($ millions) Available Unused Operating facilities (1) (note 15) 975 508 Syndicated bank facilities (2) (note 17) 4,000 3,650 End of year 4,975 4,158 (1) Consists of demand credit facilities. (2) Commercial paper outstanding is supported by the Company’s Syndicated credit facilities.

Accounts Payable and Accrued Li

Accounts Payable and Accrued Liabilities	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Accounts Payable and Accrued Liabilities	Accounts Payable and Accrued Liabilities Accounts Payable and Accrued Liabilities ($ millions) December 31, 2020 December 31, 2019 Trade payables 772 1,178 Accrued liabilities 1,115 1,954 Dividend payable (note 20) 13 126 Stock-based compensation 22 19 Derivatives due within one year 31 21 Other 176 167 End of year 2,129 3,465

Debt and Credit Facilities

Debt and Credit Facilities	12 Months Ended
	Dec. 31, 2020
Disclosure of borrowing costs [Abstract]
Debt and Credit Facilities	Debt and Credit Facilities Short-term Debt December 31, 2020 December 31, 2019 ($ millions) Commercial paper (1) — 550 Bankers' Acceptances 40 — (1) The weighted average interest rate as at December 31, 2019 was 1.98% per annum. Canadian $ Amount U.S. $ Denominated Long-term Debt Maturity December 31, 2020 December 31, 2019 December 31, 2020 December 31, 2019 ($ millions) Long-term debt Syndicated Credit Facility 2022 350 — — — 3.95% notes (1)(3) 2022 637 648 500 500 4.00% notes (1)(3) 2024 957 973 750 750 3.55% notes (4) 2025 750 750 — — 3.60% notes (4) 2027 750 750 — — 3.50% notes (4) 2028 1,250 — — — 4.40% notes (1)(3) 2029 957 973 750 750 6.80% notes (1)(3) 2037 493 501 387 387 Debt issue costs (2) (27) (25) — — Long-term debt 6,117 4,570 2,387 2,387 Long-term debt due within one year 5.00% notes (4) 2020 — 400 — — Long-term debt due within one year — 400 — — (1) The U.S. dollar denominated debt is designated as a hedge of the Company’s net investment in selected foreign operations with a U.S. dollar functional currency. Refer to Note 25 for Foreign Currency Risk Management. (2) Calculated using the effective interest rate method. (3) The 3.95%, the 4.00%, the 4.40% and the 6.80% notes represent unsecured securities under a trust indenture dated September 11, 2007. (4) The 5.00%, the 3.55%, the 3.60% and the 3.50% notes represent unsecured securities under a trust indenture dated December 21, 2009. Credit Facilities On April 7, 2020 the Company entered into a $500 million unsecured non-revolving term credit facility. Interest payable is based on pricing referenced to CAD Bankers’ Acceptance or CAD Prime Rates. The facility was repaid on October 5, 2020. As at December 31, 2020 the covenant under the Company’s credit facilities was a debt to capital ratio, calculated as total debt (long-term debt including long-term debt due within one year and short-term debt) and certain adjusting items specified in the credit agreements divided by total debt and shareholders’ equity. This covenant is used to assess the Company’s financial strength. If the Company does not comply with the covenant under the credit facilities, there is risk that repayment could be accelerated. The Company was in compliance with this covenant under its credit facilities at December 31, 2020, and assessed the risk of non-compliance to be low. As at December 31, 2020, the Company had $350 million outstanding under its $2.0 billion committed syndicated credit facility expiring June 19, 2022 (December 31, 2019 – no direct borrowings), and no direct borrowings under its $2.0 billion committed syndicated credit facility expiring March 9, 2024 (December 31, 2019 – no direct borrowings). Interest payable is based on Bankers’ Acceptance, CAD Prime Rate, U.S. LIBOR, or U.S. Base Rates, depending on the borrowing option selected and credit ratings assigned by certain credit rating agencies to the Company. Notes On March 15, 2019, the Company issued US$750 million in senior unsecured notes. The notes bear an annual interest rate of 4.40% and are due on April 15, 2029. The Company raised the net proceeds of the offering for general corporate purposes, which included the repayment of certain outstanding debt securities that matured in 2019. On May 1, 2019, the Company filed a universal short form base shelf prospectus (the “2019 Canadian Shelf Prospectus”) with applicable securities regulators in each of the provinces of Canada that enabled the Company to offer up to $3.0 billion of common shares, preferred shares, debt securities, subscription receipts, warrants and other units in Canada. As a result of the delisting of Husky's shares from the TSX, the Company is unable to sell securities under the 2019 Canadian Shelf Prospectus. On June 17, 2019, the Company repaid the maturing 6.15% notes. The amount paid to note holders was $402 million. On December 16, 2019, the Company repaid the maturing 7.25% notes. The amount paid to note holders was $987 million. On March 3, 2020, the Company filed a universal short form base shelf prospectus (the "2020 U.S. Shelf Prospectus”) with the Alberta Securities Commission. On March 4, 2020, the Company’s related U.S. registration statement filed with the SEC containing the 2020 U.S. Shelf Prospectus became effective which enabled the Company to offer up to US$3.0 billion of debt securities, common shares, preferred shares, subscription receipts, warrants and units of the Company in the U.S. During the period that the 2020 U.S. Shelf Prospectus and the related U.S registration statement were effective, securities could be offered in amounts, at prices and on terms set forth in a prospectus supplement. On January 26, 2021, the Company terminated the effectiveness of the U.S. registration statement. On March 12, 2020, the Company repaid the maturing 5.00% notes. The principal paid to note holders was $400 million. On August 7, 2020, the Company issued $1.25 billion of notes. The notes have a coupon of 3.50% and are due on February 7, 2028. Proceeds were for general corporate purposes, which included the repayment of Husky’s $500 million unsecured non-revolving term loan credit facility on October 5, 2020. At December 31, 2020, the Company had unused capacity of $1.75 billion under the 2019 Canadian Shelf Prospectus and US$3.0 billion under the 2020 U.S. Shelf Prospectus and related U.S. registration statement. The Company’s notes, credit facilities and short-term lines of credit rank equally in right of payment. Reconciliation of Changes of Liabilities to Cash Flows from Financing Activities Liabilities ($ millions) Short-term debt Long-term debt due within one year Long-term debt Other long-term liabilities Lease liabilities due within one year Lease liabilities December 31, 2019 550 400 4,570 454 109 1,353 Changes from financing cash flows Long-term debt issuance, net — (1,400) 2,600 — — — Short-term debt issuance, net (510) — — — — — Debt issue costs — — (7) — — — Finance lease payments — — — — (111) — Total change from financing cash flows (510) (1,400) 2,593 — (111) — Other changes – liability-related Foreign exchange — — — (1) — — Fair value changes — — — 8 — 32 Net additions of lease liabilities — — — — — 23 Reclassification — 1,000 (1,000) — 107 (107) Deferred revenue — — — (115) — — Amortization of debt issuance costs — — 4 — — — Foreign exchange recognized in OCI — — (50) — (1) (2) Other — — — 64 (2) (1) Total other changes – liability related — 1,000 (1,046) (44) 104 (55) December 31, 2020 40 — 6,117 410 102 1,298

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Asset Retirement Obligations	Asset Retirement Obligations At December 31, 2020, the estimated total undiscounted inflation-adjusted amount required to settle the Company’s ARO was $9.5 billion (December 31, 2019 – $10.0 billion). These obligations will be settled based on the useful lives of the underlying assets, which currently extend an average of 45 years (December 31, 2019 – 45 years) into the future. This amount has been discounted using credit-adjusted risk-free rates of 3.6% to 6.2% (December 31, 2019 – 3.9% to 4.4%) and an inflation rate of 2% (December 31, 2019 – 2%). Obligations related to future environmental remediation and cleanup of oil and gas assets are included in the estimated ARO. While the provision is based on management’s best estimates of future costs, discount rates and the economic lives of the assets, there is uncertainty regarding the amount and timing of incurring these costs. A reconciliation of the carrying amount of asset retirement obligations at December 31, 2020 and 2019 is set out below: Asset Retirement Obligations ($ millions) 2020 2019 Beginning of year 2,755 2,424 Additions 63 76 Liabilities settled (39) (276) Liabilities disposed (39) (6) Change in discount rate (544) 285 Change in estimates (146) 156 Exchange adjustment 8 (10) Accretion (note 22) 104 106 End of year 2,162 2,755 Expected to be incurred within 1 year 94 112 Expected to be incurred beyond 1 year 2,068 2,643

Other Long-term Liabilities

Other Long-term Liabilities	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Other Long-term Liabilities	Other Long-term Liabilities Other Long-term Liabilities ($ millions) December 31, 2020 December 31, 2019 Employee future benefits (note 23) 233 214 Stock-based compensation 19 19 Deferred revenue 37 152 Other 121 69 End of year 410 454 Deferred revenue Deferred revenue relates to take-or-pay commitments, with respect to natural gas production volumes from the Liwan 3-1 field in Asia Pacific, not taken by the purchaser. As per the terms of the agreement, the purchaser has until the end of the agreement to take these volumes. ($ millions) December 31, 2020 December 31, 2019 Beginning of year 152 205 Revenue recognized (115) (42) Exchange adjustment — (11) End of year 37 152

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Disclosure of income tax [Abstract]
Income Taxes	Income Taxes The major components of income tax expense (recovery) for the years ended December 31, 2020 and 2019 were as follows: Income Tax Expense (Recovery) ($ millions) 2020 2019 Current income tax Current income tax charge 183 174 Adjustments to current income tax estimates 19 1 202 175 Deferred income tax Relating to origination and reversal of temporary differences (3,248) (723) Adjustments to deferred income tax estimates 58 (251) (3,190) (974) Included in recovery of income taxes for the year-ended December 31, 2020, was a $2,654 million deferred income tax recovery associated with the recognition of pre-tax impairment and exploration asset write-down charges of $11,220 million on Oil and Gas Properties, Refining assets, Goodwill and the investment in the HMLP joint venture. Deferred Tax Items in OCI ($ millions) 2020 2019 Deferred tax items expensed (recovered) directly in OCI Derivatives designated as cash flow hedges (3) (3) Remeasurement of pension plans (2) 1 Exchange differences on translation of foreign operations 29 (58) Hedge of net investment 6 30 30 (30) The provision for income taxes in the consolidated statements of loss reflects an effective tax rate which differs from the expected statutory tax rate. Differences for the years ended December 31, 2020 and 2019 were as follows: Reconciliation of Effective Tax Rate ($ millions, except tax rate) 2020 2019 Earnings (loss) before income taxes Canada (8,799) (3,170) United States (4,969) 337 Other foreign jurisdictions 764 664 (13,004) (2,169) Statutory Canadian income tax rate 24.9 % 26.8 % Expected income tax (3,238) (582) Effect on income tax resulting from: Capital gains and losses 1 — Foreign jurisdictions 202 61 Non-taxable items (16) (25) Adjustments with respect to previous year 77 (250) Revaluation of foreign tax pools (12) (4) Other – net (2) 1 Income tax recovery (2,988) (799) The statutory tax rate is 24.9% in 2020 (2019 – 26.8%). The 2020 and 2019 tax rates changed due to a previously announced 2% decrease to the Alberta Provincial Tax rate (from 10% to 8%) that was accelerated to July 1, 2020. The following reconciles the movements in the deferred income tax liabilities and assets: Deferred Tax Liabilities and Assets ($ millions) January 1, 2020 Recognized in Loss Recognized in OCI December 31, 2020 Deferred tax liabilities Exploration and evaluation assets and property, plant and equipment (3,053) 2,578 (14) (489) Foreign exchange gains taxable on realization (150) 151 (4) (3) Debt issue costs (5) — — (5) Financial assets at fair value (9) 2 — (7) Other temporary differences (152) 51 — (101) Deferred tax assets Pension plans 16 10 2 28 Asset retirement obligations 666 (138) (2) 526 Loss carry-forwards 517 536 (12) 1,041 (2,170) 3,190 (30) 990 Deferred Tax Liabilities and Assets ($ millions) January 1, 2019 Recognized in Loss Recognized in OCI December 31, 2019 Deferred tax liabilities Exploration and evaluation assets and property, plant and equipment (4,089) 967 69 (3,053) Foreign exchange gains taxable on realization (174) 51 (27) (150) Debt issue costs (4) (1) — (5) Other temporary differences (28) (124) — (152) Financial assets at fair value (9) — — (9) Deferred tax assets Pension plans 8 9 (1) 16 Asset retirement obligations 654 16 (4) 666 Loss carry-forwards 468 56 (7) 517 (3,174) 974 30 (2,170) The Company has temporary differences associated with its investments in its foreign subsidiaries, branches, and interests in joint ventures. At December 31, 2020, the Company had $nil deferred tax liabilities in respect to these investments (December 31, 2019 – $nil).

Share Capital

Share Capital	12 Months Ended
	Dec. 31, 2020
Disclosure of share capital, reserves and other equity interest [Abstract]
Share Capital	Share Capital Common Shares The Company is authorized to issue an unlimited number of no par value common shares. Common Shares Number of Shares Amount ($ millions) December 31, 2018, 2019 and 2020 1,005,121,738 7,293 Quarterly dividends may be declared in an amount expressed in dollars per common share or could be paid by way of issuance of a fraction of a common share per outstanding common share determined by dividing the dollar amount of the dividend by the volume-weighted average trading price of the Common Shares on the principal stock exchange on which the common shares are traded. The volume-weighted average trading price of the common shares is calculated by dividing the total value by the total volume of common shares traded over the five trading day period immediately prior to the payment date of the dividend on the common shares. Common Share Dividends ($ millions) 2020 2019 Declared Paid Declared Paid 163 276 503 503 At December 31, 2020, Common Share dividends payable were $13 million (December 31, 2019 – $126 million). Preferred Shares The Company is authorized to issue an unlimited number of no par value preferred shares. Cumulative Redeemable Preferred Shares Number of Shares Amount ($ millions) December 31, 2018, 2019 and 2020 36,000,000 874 Cumulative Redeemable Preferred Shares Dividends ($ millions) 2020 2019 Declared Paid Declared Paid Series 1 Preferred Shares 6 6 6 6 Series 2 Preferred Shares 1 1 1 1 Series 3 Preferred Shares 12 12 12 12 Series 5 Preferred Shares 9 9 9 9 Series 7 Preferred Shares 7 7 7 7 35 35 35 35 At December 31, 2020, Preferred Share dividends payable were $nil (December 31, 2019 - $nil). Holders of the Cumulative Redeemable Preferred Shares, Series 1 (the ”Series 1 Preferred Shares”) are entitled to receive a cumulative quarterly fixed dividend yielding 2.404% annually for a five five five five Holders of the Series 2 Preferred Shares are entitled to receive a cumulative quarterly floating rate dividend that is reset every quarter for a five three five Holders of the Cumulative Redeemable Preferred Shares, Series 3 (the ”Series 3 Preferred Shares”) are entitled to receive a cumulative quarterly fixed dividend yielding 4.689% annually for the initial period ending December 31, 2024 as and when declared by the Company’s Board of Directors. Thereafter, the dividend rate will be reset every five five five On March 2, 2020, the Company announced that it did not intend to exercise its right to redeem its Cumulative Redeemable Preferred Shares, Series 5 (the "Series 5 Preferred Shares") on March 31, 2020. As a result, subject to certain conditions, the holders of Series 5 Preferred Shares were notified of their right to choose one of the following options with regard to their shares: retain any or all of their Series 5 Preferred Shares and continue to receive an annual fixed-rate dividend paid quarterly; or convert, on a one-for-one basis, any or all of their Series 5 Preferred Shares into Cumulative Redeemable Preferred Shares, Series 6 (the "Series 6 Preferred Shares") of Husky Energy and receive a floating rate quarterly dividend. In March 2020, 40,800 Series 5 Preferred Shares were tendered for conversion, which is less than the one million shares required to give effect to conversions into Series 6 Preferred Shares. As a result, none of the Series 5 Preferred Shares were converted into Series 6 Preferred Shares on March 31, 2020. The new annual fixed-rate dividend applicable to the Series 5 Preferred Shares for the five-year period commencing March 31, 2020, to, but excluding, March 31, 2025 is 4.591%, being equal to the sum of the Government of Canada five-year bond yield of 1.021% plus 3.57% in accordance with the terms of the Series 5 Preferred Shares. On June 1, 2020, the Company announced that it did not intend to exercise its right to redeem its Cumulative Redeemable Preferred Shares, Series 7 (the "Series 7 Preferred Shares") on June 30, 2020. As a result, subject to certain conditions, the holders of Series 7 Preferred Shares were notified of their right to choose one of the following options with regard to their shares: retain any or all of their Series 7 Preferred Shares and continue to receive an annual fixed-rate dividend paid quarterly; or convert, on a one-for-one basis, any or all of their Series 7 Preferred Shares into Cumulative Redeemable Preferred Shares, Series 8 (the "Series 8 Preferred Shares") of Husky Energy and receive a floating rate quarterly dividend. In June 2020, 212,461 Series 7 Preferred Shares were tendered for conversion, which is less than the one million shares required to give effect to conversions into Series 8 Preferred Shares. As a result, none of the Series 7 Preferred Shares were converted into Series 8 Preferred Shares on June 30, 2020. The new annual fixed-rate dividend applicable to the Series 7 Preferred Shares for the five-year period commencing June 30, 2020, to, but excluding, June 30, 2025 is 3.935%, being equal to the sum of the Government of Canada five-year bond yield of 0.415% plus 3.52% in accordance with the terms of the Series 7 Preferred Shares. Stock Option Plan Pursuant to the Incentive Stock Option Plan (the “Option Plan”), the Company may grant from time to time to executive officers and certain employees of the Company options to purchase common shares of the Company. The term of each option is five years, and vests one-third on each of the first three anniversary dates from the grant date. The Option Plan provides the option holder with the right to exercise the option to acquire one common share at the exercise price or surrender the option for a cash payment. The exercise price of the option is equal to the weighted average trading price of the Company’s common shares during the five trading days prior to the grant date. When the stock option is surrendered to the Company, the cash payment is equal to the excess of the aggregate fair market value of the common shares able to be purchased pursuant to the vested and exercisable portion of such stock options on the date of surrender over the aggregate exercise price for those common shares pursuant to those stock options. The fair market value of common shares is calculated as the closing price of the common shares on the date on which board lots of common shares have traded immediately preceding the date a holder of the stock options provides notice to the Company that they wish to surrender their stock options to the Company in lieu of exercise. Included in accounts payable and accrued liabilities and other long-term liabilities in the consolidated balance sheets at December 31, 2020 was $13 million (December 31, 2019 – $4 million) representing the estimated fair value of options outstanding. The total expense recognized in selling, general and administrative expenses in the consolidated statements of loss for the Option Plan for the year ended December 31, 2020 was $9 million (December 31, 2019 – recovery of $6 million). At December 31, 2020, the intrinsic value of stock options exercisable for cash was $9 million (December 31, 2019 – less than one million). The following options to purchase common shares have been awarded to officers and certain other employees: Outstanding and Exercisable Options 2020 2019 Number of Options (thousands) Weighted Average ($) Number of Options (thousands) Weighted Average ($) Outstanding, beginning of year 18,498 17.75 19,967 21.48 Granted (1) 6,113 2.86 4,241 14.31 Surrendered for cash — — (4) 15.67 Expired or forfeited (5,728) 20.78 (5,706) 28.27 Outstanding, end of year 18,883 12.01 18,498 17.75 Exercisable, end of year 9,651 16.11 10,596 19.27 (1) Options granted during the year ended December 31, 2020 were attributed a fair value of $0.36 per option (December 31, 2019 – $2.34) at grant date. Outstanding and Exercisable Options Outstanding Options Exercisable Options Range of Exercise Price Number of Options (thousands) Weighted Average Exercise Prices ($) Weighted Average (years) Number of Options (thousands) Weighted Average Exercise Prices ($) $2.77 - $8.00 5,650 2.85 4.17 — — $8.01 - $15.92 6,085 14.88 1.92 3,802 15.22 $15.93 - $21.87 7,148 16.80 1.69 5,849 16.70 December 31, 2020 18,883 12.01 2.51 9,651 16.11 The fair value of the share options is estimated at each reporting date using the Black-Scholes option pricing model, taking into account the terms and conditions upon which the share options are granted and for the performance options, the current likelihood of achieving the specified target. The following table lists the assumptions used in the Black-Scholes option pricing model for the share options and performance options: Black-Scholes Assumptions December 31, 2020 December 31, 2019 Tandem Tandem Dividend per option 0.21 0.42 Range of expected volatilities used (percent) 47.2 - 90.2 27.5 - 35.5 Range of risk-free interest rates used (percent) 0.06 - 0.39 1.66 - 1.74 Expected life of share options from vesting date (years) 1.99 1.97 Expected forfeiture rate (percent) 8.6 8.8 Weighted average exercise price 13.71 18.19 Weighted average fair value 0.87 0.25 The expected life of the share options is based on historical data and current expectations and is not necessarily indicative of exercise patterns that may occur. The expected volatility reflects the assumption that the historical volatility over a period similar to the expected life of the options is indicative of future trends, which may also not necessarily be the actual outcome. Performance Share Units The Company has a Performance Share Unit Plan for executive officers and certain employees of the Company. The term of each PSU is three years, and the PSU vests on the second and third anniversary dates of the grant date in percentages determined by the Compensation Committee based on the Company’s total shareholder return relative to a peer group of companies and achieving a ROCIU target set by the Company. ROCIU equals net loss plus after-tax interest expense divided by the two-year average capital employed, less any capital invested in assets that are not in use. Net loss is adjusted for the difference between actual realized and budgeted commodity prices and foreign exchange rates and other actual and budgeted exceptional items. Upon vesting, PSU holders receive a cash payment equal to the number of vested PSUs multiplied by the weighted average trading price of the Company’s common shares for the five preceding trading days. As at December 31, 2020, the carrying amount of the liability relating to PSUs was $29 million (December 31, 2019 – $34 million). The total expense recognized in selling, general and administrative expenses in the consolidated statements of loss for the PSUs for the year ended December 31, 2020 was $7 million (2019 – $4 million). The Company paid out $12 million (2019 – $34 million) for performance share units which vested in the year. The weighted average contractual life of the PSUs at December 31, 2020 was two years (December 31, 2019 – two years). The number of PSUs outstanding was as follows: Performance Share Units 2020 2019 Beginning of year 14,318,642 11,606,644 Granted 10,828,280 7,673,960 Exercised (2,111,552) (2,429,816) Forfeited (3,735,485) (2,532,146) Outstanding, end of year 19,299,885 14,318,642 Vested, end of year 4,621,999 3,264,840 Loss per Share Loss per Share ($ millions) 2020 2019 Net loss (10,016) (1,370) Effect of dividends declared on preferred shares in the year (35) (35) Net loss – basic (10,051) (1,405) Dilutive effect of accounting for stock options 4 (15) Net loss – diluted (10,047) (1,420) (millions) Weighted average common shares outstanding – basic 1,005.1 1,005.1 Weighted average common shares outstanding – diluted 1,005.1 1,005.1 Loss per share – basic ($/share) (10.00) (1.40) Loss per share – diluted ($/share) (10.00) (1.41) For the year ended December 31, 2020, 13 million tandem options (2019 – 18 million) were excluded from the calculation of diluted loss per share as these options were anti-dilutive.

Production, Operating and Trans

Production, Operating and Transportation and Selling, General, and Administrative Expenses	12 Months Ended
	Dec. 31, 2020
Analysis of income and expense [abstract]
Production, Operating and Transportation and Selling, General and Administrative Expenses	Production, Operating and Transportation and Selling, General and Administrative Expenses The following table summarizes production, operating and transportation expenses in the consolidated statements of loss for the years ended December 31, 2020 and 2019: Production, Operating and Transportation Expenses ($ millions) 2020 2019 Services and support costs 1,119 1,255 Salaries and benefits 576 773 Materials, equipment rentals and leases 191 250 Energy and utility 476 482 Licensing fees 160 204 Transportation 18 17 Other 20 49 Total production, operating and transportation expenses (1) 2,560 3,030 (1) Results reported for 2019 have been recast to reflect various reclassifications due to a change in presentation of the Integrated Corridor and Offshore business units. The following table summarizes selling, general and administrative expenses in the consolidated statements of loss for the years ended December 31, 2020 and 2019: Selling, General and Administrative Expenses ($ millions) 2020 2019 Employee costs (1) 443 450 Stock-based compensation expense (recovery) (2) 16 (2) Contract services 128 133 Equipment rentals and leases 16 11 Maintenance and other 142 101 Total selling, general and administrative expenses 745 693 (1) Employee costs are comprised of salary and benefits earned during the year, plus cash bonuses awarded during the year. Annual bonus awards settled in shares are included in stock-based compensation expense.

Financial Items

Financial Items	12 Months Ended
	Dec. 31, 2020
Disclosure of additional information [Abstract]
Financial Items	Financial Items Financial Items ($ millions) 2020 2019 Foreign exchange gain Non-cash working capital 7 17 Other foreign exchange 7 27 Net foreign exchange gain 14 44 Finance income 25 74 Finance expenses Long-term debt (251) (310) Lease liabilities (note 10) (97) (106) Other (7) (6) (355) (422) Interest capitalized (1) 60 177 (295) (245) Accretion of asset retirement obligations (note 18) (104) (106) Finance expenses (399) (351) Total Financial Items (360) (233) (1) Interest capitalized on project costs is calculated using the Company’s annualized effective interest rate of 3% (2019 – 5%).

Pensions and Other Post-employm

Pensions and Other Post-employment Benefits	12 Months Ended
	Dec. 31, 2020
Disclosure of employee benefits [Abstract]
Pensions and Other Post-employment Benefits	Pensions and Other Post-employment Benefits The Company currently provides defined contribution pension plans for all qualified employees and other post-employment benefit plans to its retirees. The other post-employment benefit plans provide certain retired employees with health care and dental benefits. The Company also maintains one defined benefit pension plan, which is closed to new entrants. The defined benefit pension plan provides pension benefits to certain employees based on years of service and final average earnings. The amount and timing of funding of this plan is subject to the funding policy as approved by the Board of Directors. The measurement date of all plan assets and the accrued benefit obligations was December 31, 2020. The Company is required to file an actuarial valuation of its defined benefit pension with the provincial or state regulator at least every three years. The most recent actuarial valuation was December 31, 2019 for the U.S defined benefit plan. The most recent actuarial valuation was April 30, 2018 for the Canadian Other Post-employment benefit plan. The most recent actuarial valuation of the U.S. Other Post-employment benefit plan was January 18, 2019. Defined Contribution Pension Plan During the year ended December 31, 2020, the Company recognized a $56 million expense (2019 – $59 million) for the defined contribution and U.S. 401(k) plans in net loss. Defined Benefit Pension Plans (“DB Pension Plan”) and Other Post-employment Benefit Plans (“OPEB Plans”) Defined Benefit Obligations DB Pension Plans OPEB Plans ($ millions) 2020 2019 2020 2019 Beginning of year 39 79 201 199 Current service cost — — 9 10 Interest cost 1 2 6 7 Benefits paid (2) (3) (5) (4) Past service cost — 3 — (29) Settlements — (49) — — Remeasurements Actuarial gain – experience — — (1) (1) Actuarial loss – financial assumptions 4 9 14 20 Effect of changes in foreign exchange rates (1) (2) — (1) End of year 41 39 224 201 Fair Value of Plan Assets DB Pension Plans OPEB Plans ($ millions) 2020 2019 2020 2019 Beginning of year 31 71 — — Contributions by employer — (1) 3 2 Benefits paid (2) (3) (3) (2) Interest income 1 2 — — Return on plan assets greater than discount rate 3 16 — — Settlements — (52) — — Effect of changes in foreign exchange rates (1) (2) — — End of year 32 31 — — Funded status DB Pension Plans OPEB Plans ($ millions) 2020 2019 2020 2019 Net liability (9) (8) (224) (201) The Company has accrued the total net liability for the DB Pension Plan and the OPEB Plans in the consolidated balance sheets in other long-term liabilities. On July 25, 2019, the Company completed the transaction related to the Canadian DB Pension Plan initiated on July 25, 2017. The transaction settled the remaining service costs for active plan members, thereby settling the defined benefit obligation related to active plan members. This resulted in the Company recognizing a $5 million actuarial gain (net of tax of $1 million) in other comprehensive loss in 2019. The composition of the DB Pension Plan assets at December 31, 2020 and 2019 was as follows: DB Pension Plan Assets (percent) Target allocation 2020 2019 Money market type funds — — — Equity securities 35 35 35 Debt securities 65 65 65 The following table summarizes amounts recognized in net loss and OCI for the DB Pension Plans and the OPEB Plans for the years ended December 31, 2020 and 2019: DB Pension Plans OPEB Plans ($ millions) 2020 2019 2020 2019 Amounts recognized in net loss Current service cost — — 9 10 Past service cost — 3 — (29) Net Interest cost — — 6 7 Benefit cost — 3 15 (12) Remeasurements Actuarial gain due to liability experience — — (1) (1) Actuarial loss due to liability assumption changes 4 9 14 20 Gain on plan assets (3) (16) — — Remeasurement effects recognized in OCI 1 (7) 13 19 The following long-term assumptions were used to estimate the value of the defined benefit obligations, the plan assets and the OPEB Plans: Assumptions DB Pension Plans OPEB Plans (percent) 2020 2019 2020 2019 Discount rate for benefit expense and obligation 0.8 - 3.2 2.3 - 4.2 2.5 - 3.2 3.0 -3.7 Rate of compensation expense 3.5 3.5 N/A N/A The average health care cost trend rate used for the benefit expense for the Canadian OPEB Plan was 6.0% for 2018, 2019 and 2020, grading 0.5% per year for 2 years to 5.0% in 2022 and thereafter. The average health care cost trend rate used for the obligation related to the Canadian OPEB Plan was 6.0% for 2018, 2019 and 2020, grading 0.5% per year for 2 years to 5.0% in 2022 and thereafter. The average health care cost trend rate used for the benefit expense for the U.S. OPEB Plan was 6.5% for 2018, grading 0.25% per year for 6 years to 5.0% per year in 2026 and thereafter. The average health care cost trend rate used for the obligation related to the U.S. OPEB Plan was 6.5% for 2019 and 2020, grading 0.25% per year for 6 years to 5.0% in 2026 and thereafter. The sensitivity of the defined benefit and OPEB obligations to changes in relevant actuarial assumption is shown below: Sensitivity Analysis DB Pension Plans OPEB Plans ($ millions) 1% increase 1% decrease 1% increase 1% decrease Discount rate (5) 6 (25) 31 Health care cost trend rate N/A N/A 25 (22)

Cash Flows - Change in Non-cash

Cash Flows - Change in Non-cash Working Capital	12 Months Ended
	Dec. 31, 2020
Disclosure of cash flow statement [Abstract]
Cash Flows - Change in Non-cash Working Capital	Cash Flows – Change in Non-cash Working Capital Non-cash Working Capital ($ millions) 2020 2019 Decrease (increase) in non-cash working capital Accounts receivable 724 (176) Inventories 377 (502) Prepaid expenses (14) (30) Accounts payable and accrued liabilities (1,152) 604 Change in non-cash working capital (65) (104) Relating to: Operating activities 347 (280) Financing activities 11 3 Investing activities (423) 173

Financial Instruments and Risk

Financial Instruments and Risk Management	12 Months Ended
	Dec. 31, 2020
Disclosure of detailed information about financial instruments [abstract]
Financial Instruments and Risk Management	Financial Instruments and Risk Management Financial Instruments The Company’s financial instruments include cash and cash equivalents, accounts receivable, restricted cash, accounts payable and accrued liabilities, short-term debt, long-term debt, derivatives , portions of other assets, lease liabilities and other long-term liabilities. Derivative instruments are measured at fair value through profit or loss (”FVTPL”). The Company’s remaining financial instruments are measured at amortized cost. For financial instruments measured at amortized cost, the carrying values approximate their fair value with the exception of long-term debt. The following table summarizes the Company’s financial instruments that are carried at fair value in the consolidated balance sheets: Financial Instruments at Fair Value ($ millions) December 31, 2020 December 31, 2019 Commodity contracts – FVTPL Natural gas (1) 33 31 Crude oil (2) 8 11 Crude oil call options (3) (23) (2) Crude oil put options (3) 8 (4) Foreign currency contracts – FVTPL Foreign currency forwards — 2 Other assets – FVTPL 1 1 End of year 27 39 (1) Natural gas contracts includes a $25 million increase at December 31, 2020 (December 31, 2019 – $4 million decrease) to the fair value of held-for-trading inventory, recognized in the consolidated balance sheets, related to third party physical purchase and sale contracts for natural gas held in storage. Total fair value of the related natural gas storage inventory was $37 million at December 31, 2020 (December 31, 2019 – $19 million). (2) Crude oil contracts includes a $5 million increase at December 31, 2020 (December 31, 2019 – $12 million increase) to the fair value of held-for-trading inventory, recognized in the consolidated balance sheets, related to third party crude oil physical purchase and sale contracts. Total fair value of the related crude oil inventory wa s $84 million at December 31, 2020 (December 31, 2019 – $136 million). (3) Excludes net unsettled premiums of $12 million. The fair value of long-term debt represents the present value of future cash flows associated with the debt. Market information, such as treasury rates and credit spreads, are used to determine the appropriate discount rates. These fair value determinations are compared to quotes received from financial institutions to ensure reasonability. At December 31, 2020, the carrying value of the Company’s long-term debt was $6.1 billion and the estimated fair value was $6.6 billion (December 31, 2019 – carrying value of $5.0 billion, estimated fair value of $5.3 billion). All financial assets and liabilities are classified as Level 2 fair value measurements, except commodity put and call options under a short-term hedging program, which are classified as Level 1 fair value measurements as they are determined using quoted market prices. During the year ended December 31, 2020, there were no transfers between Level 1 and Level 2 fair value measurements, and no transfers into or out of Level 3 fair value measurements. Risk Management Overview The Company is exposed to risks related to the volatility of commodity prices, foreign exchange rates and interest rates. It is also exposed to financial risks related to liquidity, credit and contract risks. The current challenging economic climate has significantly increased the Company’s exposure to these risks. Governments and central banks have reacted with significant monetary and fiscal interventions designed to stabilize economic conditions; however, the success of these interventions is not currently determinable. Risk management strategies and policies are employed to ensure that any exposures to risk are in compliance with the Company’s business objectives and risk tolerance levels. Responsibility for the oversight of risk management is held by the Company’s Board of Directors and is implemented and monitored by senior management within the Company. a) Market Risk i) Commodity Price Risk Management The Company uses derivative commodity instruments to manage exposure to price volatility on a portion of its crude oil and natural gas production, and it also uses firm commitments for the purchase or sale of crude oil and natural gas. These contracts meet the definition of a derivative instrument and have been recorded at their fair value in accounts receivable, inventory, other assets, accounts payable and accrued liabilities and other long-term liabilities. All derivatives are measured at fair value through profit or loss other than non-financial derivative contracts that meet the Company’s own use requirements. At December 31, 2020, the Company was party to crude oil purchase and sale derivative contracts to mitigate its exposure to fluctuations in the benchmark price between the time a sales agreement is entered into and the time inventory is delivered. The Company was also party to third party physical natural gas purchase and sale derivative contracts in order to mitigate commodity price fluctuations. For the year ended December 31, 2020, the net unrealized loss recognized on the derivative contracts was $1 million (2019 - net unrealized loss of $38 million). During the year ended December 31, 2020, the Company continued a commodity short-term hedging program using put and call options to manage risks related to volatility of commodity prices. Western Texas Intermediate Crude Oil Call and Put Option Contracts Type Transaction Term Volume (bbls/day) Price (US/$bbl) (1) Call options Sold January - March 2021 82,337 48.11 Put options Bought January - March 2021 95,380 41.25 Put options Sold January - March 2021 6,522 37.00 (1) Prices reported are the weighted average prices for the period. For the year ended December 31, 2020, the Company incurred an unrealized loss of $9 million (December 31, 2019 – $6 million). For the year ended December 31, 2020, the Company incurred a realized gain of $88 million (December 31, 2019 – $16 million). These amounts are recorded in other - net in the consolidated statements of loss. II) Foreign Exchange Risk Management The Company’s results are affected by the exchange rates between various currencies and the Company’s functional currency in Canadian dollars. As the majority of the Company’s revenues are denominated in U.S. dollars or based upon a U.S. benchmark price, fluctuations in the value of the Canadian dollar relative to the U.S. dollar may affect revenues significantly. To limit the exposure to foreign exchange risk, the Company hedges against these fluctuations by entering into short-dated foreign exchange contracts to fix the exchange rate for conversion of U.S. revenue dollars. Foreign exchange fluctuations will result in a change in value of the U.S. dollar denominated debt and related finance expense when expressed in Canadian dollars. At December 31, 2020, the Company had designated US $2.4 billion denominated debt as a hedge of the Company’s selected net investments in its foreign operations with a U.S. dollar functional currency (December 31, 2019 – US$2.4 billion). For the year ended December 31, 2020, the unrealized gain arising from the translation of the debt was $44 million (December 31, 2019 – unrealized gain of $146 million), net of tax expense of $6 million (December 31, 2019 – expense of $30 million), which was recorded in hedge of net investment within OCI . III) Interest Rate Risk Management The Company is exposed to fluctuations in short-term interest rates as the Company maintains a portion of its debt capacity in revolving and floating rate bank facilities and invests surplus cash in short-term debt instruments and money market instruments. The Company is also exposed to interest rate risk when fixed rate debt instruments are maturing and require refinancing or when new debt capital needs to be raised. By maintaining a mix of both fixed and floating rate debt, the Company mitigates some of its exposure to interest rate changes. The optimal mix maintained will depend on market conditions. The Company may also enter into fair value or cash flow hedges using interest rate swaps. IV) Offsetting Financial Assets and Liabilities The tables below outline the financial assets and financial liabilities that are subject to set-off rights and related arrangements, and the effect of those rights and arrangements on the consolidated balance sheets: As at December 31, 2020 Offsetting Financial Assets and Liabilities ($ millions) Gross Amount Amount Offset Net Amount Financial Assets Financial derivatives 69 (51) 18 Normal purchase and sale agreements 391 (311) 80 End of year 460 (362) 98 Financial Liabilities Financial derivatives (116) 87 (29) Normal purchase and sale agreements (540) 307 (233) End of year (656) 394 (262) As at December 31, 2019 Offsetting Financial Assets and Liabilities ($ millions) Gross Amount Amount Offset Net Amount Financial Assets Financial derivatives 79 (26) 53 Normal purchase and sale agreements 817 (274) 543 End of year 896 (300) 596 Financial Liabilities Financial derivatives (48) 25 (23) Normal purchase and sale agreements (843) 281 (562) End of year (891) 306 (585) V) Market Risk Sensitivity Analysis A sensitivity analysis for commodities and foreign currency exchange risks has been calculated by increasing or decreasing commodity prices or foreign currency exchange rates, as appropriate. These sensitivities represent the increase or decrease in loss before income taxes resulting from changing the relevant rates, with all other variables held constant. These sensitivities have only been applied to financial instruments held at fair value. The Company’s process for determining these sensitivities has not changed during the year. Commodity Price Risk (1) ($ millions) 10% price increase 10% price decrease Crude oil price (8) 8 Natural gas price (2) 2 (1) Based on average crude oil and natural gas market prices as at December 31, 2020. b) Financial Risk i) Liquidity Risk Management Liquidity risk is the risk that the Company will not be able to meet its financial obligations as they become due. Liquidity risk also includes the risk of not being able to liquidate assets in a timely manner at a reasonable price. The Company’s processes for managing liquidity risk include ensuring, to the extent possible, that it has access to multiple sources of capital including cash and cash equivalents, cash from operating activities, undrawn credit facilities and capacity to raise capital from various debt and equity capital markets under its shelf prospectuses. The Company prepares annual capital expenditure budgets, which are monitored and updated as required. In addition, the Company requires authorizations for expenditures on projects, which assists with the management of capital. Since the Company operates in the oil and gas industry, it requires significant cash to fund capital programs necessary to maintain or increase production, develop reserves, acquire strategic oil and gas assets and repay maturing debt. The Company’s capital programs have been funded principally by cash provided from operating activities and issuances of debt and equity. During times of low oil and gas prices, a portion of capital programs can generally be deferred. However, due to the long cycle times and the importance to future cash flow of maintaining the Company’s production, it may be necessary to utilize alternative sources of capital to continue the Company’s strategic investment plan during periods of low commodity prices. As a result, the Company frequently evaluates the options available with respect to sources of short and long-term capital resources. Occasionally, the Company will economically hedge a portion of its production to protect cash flow in the event of commodity price declines. The Company had the following available credit facilities as at December 31, 2020: Credit Facilities ($ millions) Available Unused Operating facilities (1) (note 15) 975 508 Syndicated bank facilities (2) (note 17) 4,000 3,650 End of year 4,975 4,158 (1) Consists of demand credit facilities. (2) Commercial paper outstanding is supported by the Company’s Syndicated credit facilities. In addition to the credit facilities listed above, the Company had unused capacity under the Canadian Shelf Prospectus of $1.75 billion and unused capacity under the U.S Shelf Prospectus and related U.S registration statement of US$3.0 billion. The ability of the Company to raise additional capital utilizing these Shelf Prospectuses is dependent on market conditions. The Company believes it has sufficient funding through the use of these facilities and access to the capital markets to meet its future capital requirements. ii) Credit and Contract Risk Management Credit and contract risk represent the financial loss that the Company would suffer if a counterparty in a transaction fails to meet its obligations in accordance with the agreed terms. The Company actively manages its exposure to credit and contract execution risk from both a customer and a supplier perspective. The Company’s accounts receivables are broad based with customers in the energy industry and midstream and end user segments and are subject to normal industry risks. The Company’s policy to mitigate credit risk includes granting credit limits consistent with the financial strength of the counterparties and customers, requiring financial assurances as deemed necessary, reducing the amount and duration of credit exposures and close monitoring of all accounts. The Company is closely monitoring counterparty and customer risk in the current economic climate. The Company had one external customer that constituted more than 10% of gross revenues during the years ended December 31, 2020 and December 31, 2019. Sales to this customer were approximately $2.3 billion for the year ended December 31, 2020 (December 31, 2019 – $3.9 billion). Cash and cash equivalents include cash bank balances and short-term deposits maturing in less than three months. The Company manages the credit exposure related to short-term investments by monitoring exposures daily on a per issuer basis relative to predefined investment limits. The carrying amounts of cash and cash equivalents, accounts receivable and restricted cash represent the Company’s maximum credit exposure. The Company’s accounts receivable was aged as follows at December 31, 2020: Accounts Receivable Aging ($ millions) December 31, 2020 Current 1,076 Past due (1 – 30 days) 63 Past due (31 – 60 days) 4 Past due (61 – 90 days) 3 Past due (more than 90 days) 9 Provision for expected credit losses (36) 1,119 The Company recognizes a valuation provision when collection of accounts receivable is in doubt. Accounts receivable are impaired directly when collection is no longer expected. For the year ended December 31, 2020, the Company wrote off $1 million (December 31, 2019 – $4 million) of uncollectible receivables.
Disclosure of detailed information about hedged items [text block]	Western Texas Intermediate Crude Oil Call and Put Option Contracts Type Transaction Term Volume (bbls/day) Price (US/$bbl) (1) Call options Sold January - March 2021 82,337 48.11 Put options Bought January - March 2021 95,380 41.25 Put options Sold January - March 2021 6,522 37.00 (1) Prices reported are the weighted average prices for the period.

Government grants

Government grants	12 Months Ended
	Dec. 31, 2020
Government Grants [Abstract]
Disclosure of government grants [text block]	Government GrantsFor year ended December 31, 2020, the Company recorded pre-tax recoveries for the Canadian Emergency Wage Subsidy of $82 million (December 31, 2019 – $nil), which is included in other-net in the consolidated statements of loss.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2020
Disclosure of related party [Abstract]
Related Party Transactions	Related Party Transactions The following table lists the Company’s significant subsidiaries and jointly-controlled entities and their respective places of incorporation, continuance or organization, as the case may be, and the Company’s percentage equity interest (to the nearest whole number) as at December 31, 2020. All of the entities listed below, except as otherwise indicated, are 100% beneficially owned, or controlled or directed, directly or indirectly, by the Company. Significant Subsidiaries and Joint Operations % Jurisdiction Husky Oil Operations Limited 100 Alberta Husky Energy International Corporation 100 Alberta Lima Refining Company 100 Delaware Husky Marketing and Supply Company 100 Delaware Husky Oil Limited Partnership 100 Alberta Husky Canadian Petroleum Marketing Partnership 100 Alberta Husky Energy Marketing Partnership 100 Alberta Sunrise Oil Sands Partnership 50 Alberta BP-Husky Refining LLC 50 Delaware The Company performs management services as the operator of the assets held by HMLP for which it recovers shared service costs. The Company is also the contractor for HMLP and constructs its assets on a cost recovery basis with certain restrictions. HMLP charges an access fee to the Company for the use of its pipeline systems in performing the Company’s blending business, and the Company also pays for transportation and storage services. These transactions were related party transactions as of December 31, 2020, as the Company has a 35% ownership interest in HMLP and the remaining ownership interests in HMLP belong to PAH and CKI, which are affiliates of one of the Company’s principal shareholders prior to the completion of the business combination with Cenovus. For the year ended December 31, 2020, the Company charged HMLP $250 million (December 31, 2019 – $424 million) related to construction costs and management services. For the year ended December 31, 2020, the Company had purchases from HMLP of $239 million (December 31, 2019 – $219 million) related to the use of the pipeline for the Company’s blending activities, transportation and storage activities, received distributions of $144 million (December 31, 2019 – $94 million) and paid capital contributions of $83 million (December 31, 2019 – $37 million). At December 31, 2020, the Company had $23 million due from HMLP, of which $10 million relates to unbilled revenue from construction contracts (December 31, 2019 – $143 million and $nil, respectively). At December 31, 2020, the Company had $20 million due to HMLP (December 31, 2019 - $16 million). Key management includes Directors (executive and non-executive), Executive Officers and Senior Vice Presidents of the Company. The amounts disclosed in the table below are the amounts recognized as an expense during the reporting period related to key management personnel: Compensation of Key Management Personnel ($ millions) 2020 2019 Short-term employee benefits (1) 15 18 Stock-based compensation (2) 15 26 30 44 (1) Short-term employee benefits are comprised of salary and benefits earned during the year, plus cash bonuses awarded during the year. Annual bonus awards settled in shares are included in stock-based compensation expense. (2) Stock-based compensation expense represents the cost to the Company for participation in share-based payment plans.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies [Abstract]
Commitments and Contingencies	Commitments and Contingencies At December 31, 2020, the Company had commitments that require the following minimum future payments, which are not accrued in the consolidated balance sheets: Minimum Future Payments for Commitments ($ millions) Within 1 year After 1 year but not more than 5 years More than 5 years Total Operating agreements (1) 97 381 525 1,003 Firm transportation agreements (1)(4) 552 2,396 4,473 7,421 Unconditional purchase obligations (2) 1,766 3,327 3,324 8,417 Lease rentals and exploration work agreements 74 244 838 1,156 Obligations to fund equity investee (3) 54 319 280 653 2,543 6,667 9,440 18,650 (1) Included in operating agreements and firm transportation agreements are blending and storage agreements and transportation commitments of $1.2 billion and $1.7 billion respectively with HMLP. (2) Includes processing services, distribution services, insurance premiums, drilling services, natural gas purchases and the purchase of refined petroleum products. (3) Equity investee refers to the Company’s investment in Husky-CNOOC Madura Ltd. joint venture, which is accounted for under the equity method for consolidated financial statement purposes . (4) Includes transportation commitments of $1.7 billion (2019 – $1.6 billion) that are subject to regulatory approval or have been approved, but are not yet in service. Terms are up to 20 years subsequent to the date of commencement. The Company has income tax and royalty filings that are subject to audit and potential reassessment. The findings may impact the liabilities of the Company. The final results are not reasonably determinable at this time, and management believes that it has adequately provided for current and deferred income taxes.

Capital Disclosures

Capital Disclosures	12 Months Ended
	Dec. 31, 2020
Disclosure of additional information [Abstract]
Capital Disclosures	Capital Disclosures The Company’s objectives when managing capital are to maintain a flexible capital structure, which optimizes the cost of capital at acceptable risk, and to maintain investor, creditor and market confidence to sustain the future development of the business. The Company manages its capital structure and makes adjustments as economic conditions and the risk characteristics of its underlying assets change. The Company considers its capital structure to include shareholders’ equity and debt which was $13.2 billion as at December 31, 2020 (December 31, 2019 – $22.8 billion). To maintain or adjust the capital structure, the Company may, from time to time, issue shares, raise or paydown debt and/or adjust its capital spending to manage its current and projected debt levels. The Company monitors its financing requirements and capital structure using, among other things, non-GAAP financial metrics consisting of debt to capital employed and debt to funds from operations. Debt to capital employed is defined as long-term debt, long-term debt due within one year, and short-term debt divided by capital employed which is equal to long-term debt, long-term debt due within one year, short-term debt and shareholders’ equity. Debt to funds from operations is defined as long-term debt, long-term debt due within one year and short-term debt divided by funds from operations which is equal to cash flow – operating activities excluding change in non-cash working capital. At December 31, 2020, debt to capital employed was 46.6% (December 31, 2019 – 24.2%) and debt to funds from operations was 12.5 times (December 31, 2019 – 1.7 times). The Company is subject to a leverage covenant in its credit facilities that limits debt to capital (subject to specific definitions in the credit agreements) to less than 65%, temporarily increased to 75% until the intended amalgamation of the Company and Cenovus is completed. The Company is in compliance with this covenant and considers the risk of non-compliance low. The Company also targets a debt to funds from operations ratio of less than 2.0 times over the longer term. To facilitate the management of these ratios, the Company prepared annual budgets, which are updated depending on varying factors such as general market conditions and successful capital deployment. There were no changes in the Company’s approach to capital management from the previous year.

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events	12 Months Ended
	Dec. 31, 2020
Disclosure of events after reporting period [Abstract]
Subsequent Events	Subsequent Event On January 4, 2021 the Company announced the transaction to strategically combine with Cenovus had closed on January 1, 2021. The transaction was completed through a definitive arrangement agreement announced on October 25, 2020 under which Cenovus and Husky agreed to combine in an all-stock transaction. Pursuant to the transaction agreement, Husky common shareholders received 0.7845 of a Cenovus common share and 0.0651 of a Cenovus common share purchase warrant in exchange for each Husky common share. In addition, Husky preferred shareholders exchanged each Husky preferred share for one Cenovus preferred share with substantially identical terms. Husky common shares and preferred shares were delisted by the TSX at the close of market on January 5, 2021. In accordance with the terms of the Husky PSU plan, all PSUs as at January 1, 2021 were fully vested and paid out. The amount paid out in January 2021 was $122 million.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Disclosure of changes in accounting policies, accounting estimates and errors [Abstract]
Measurement Bases	Basis of Measurement and Statement of Compliance The consolidated financial statements have been prepared by management on a historical cost basis with some exceptions, as detailed in the accounting policies set out below in accordance with International Financial Reporting Standards (“IFRS”), as issued by the International Accounting Standards Board (“IASB”). These accounting policies have been applied consistently for all periods presented in these consolidated financial statements. These consolidated financial statements were approved by the Board of Directors on February 8, 2021. Certain prior years’ amounts have been reclassified to conform with current presentation.
Principles of Consolidation	Principles of ConsolidationThe consolidated financial statements include the accounts of Husky Energy Inc. and its subsidiaries. Subsidiaries are defined as any entities, including unincorporated entities such as partnerships, for which the Company has the power to govern their financial and operating policies to obtain benefits from their activities. The Company’s accounts reflect the proportionate share of the assets, liabilities, revenues, expenses and cash flows from the Company’s activities that are conducted jointly with third parties. Intercompany balances, net earnings and unrealized gains and losses arising from intercompany transactions are eliminated in preparing the consolidated financial statements. A portion of the Company’s activities relate to joint ventures (see Note 12), which are accounted for using the equity method.
Use of Estimates, Judgments and Assumptions	Use of Estimates, Judgments and Assumptions The timely preparation of the consolidated financial statements requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingencies, if any, as at the date of the financial statements and the reported amounts of revenue and expenses during the period. Actual results may differ from these estimates, judgments and assumptions. Estimates and underlying assumptions are reviewed on an ongoing basis. Revisions to accounting estimates are recognized in the period in which the estimates are revised and on a prospective basis. By their nature, estimates are subject to measurement uncertainty and changes in such estimates in future years could require a material change in the consolidated financial statements. These underlying assumptions are based on historical experience and other factors that management believes to be reasonable under the circumstances, and are subject to change as new events occur, as more industry experience is acquired, as additional information is obtained, and as the Company’s operating environment changes. Specifically, amounts recorded for depletion, depreciation, amortization and impairment, recoveries from insurance claims, asset retirement obligations, assets and liabilities measured at fair value, employee future benefits, income taxes and reserves and contingencies are based on estimates. Management makes judgments regarding the application of IFRS for each accounting policy. Critical judgments that have the most significant effect on the amounts recognized in the consolidated financial statements include determination of technical feasibility and commercial viability, impairment assessments, the determination of cash generating units (“CGUs”), changes in reserves estimates, the determination of a joint arrangement, the designation of the Company’s functional currency and the fair value of related party transactions. In early March 2020, the World Health Organization declared the COVID-19 coronavirus outbreak to be a pandemic. Responses to the spread of COVID-19 have resulted in significant disruption to business operations and a significant increase in economic uncertainty, with more volatile commodity prices and currency exchange rates, and a marked decline in long-term interest rates. Although economies are beginning to re-open, these events are resulting in a challenging economic climate in which it is difficult to reliably estimate the length or severity of these developments and their financial impact. The results of the potential economic downturn and any potential resulting direct and indirect impact to the Company has been considered in management’s estimates described above at the period end; however there could be a further prospective material impact in future periods.
Functional and Presentation Currency	Functional and Presentation Currency The consolidated financial statements are presented in Canadian dollars, which is the Company’s functional currency. All financial information is presented in millions of Canadian dollars, except per share amounts and unless otherwise stated. The designation of the Company’s functional currency is a management judgment based on the currency of the primary economic environment in which the Company operates.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand less outstanding cheques and deposits with an original maturity of less than three months at the time of purchase. When outstanding cheques are in excess of cash on hand and short-term deposits, and the Company has the ability to net settle, the excess is reported in bank operating loans. Cash and cash equivalents held that are not available for use are classified as restricted cash. When restricted cash is not expected to be used within 12 months, it is classified as a non-current asset.
Inventories	InventoriesCrude oil, natural gas, refined petroleum products and sulphur inventories are valued at the lower of cost or net realizable value. Cost is determined using average cost or on a first-in, first-out basis, as appropriate. Materials, parts and supplies are valued at the lower of average cost or net realizable value. Cost consists of raw material, labour, direct overhead, operating costs, transportation and depreciation, depletion and amortization. Commodity inventories held for trading purposes are carried at fair value and measured at fair value less costs to sell based on Level 2 observable inputs, refer to policy Note 3 (l). Any changes in commodity trading inventory fair value are included as gains or losses in Marketing and Other in the consolidated statements of loss during the period of change. Previous inventory impairment provisions are reversed when there is a change in the condition that caused the impairment and the inventory remains on hand. Unrealized intersegment net earnings on inventory sales are eliminated.
Precious Metals	Precious MetalsThe Company uses precious metals in conjunction with a catalyst as part of the downstream upgrading and refining processes. These precious metals remain intact; however, there is a loss during the reclamation process. The estimated loss is amortized to production and operating expenses over the period that the precious metal is in use, which is approximately two to five years. After the reclamation process, the actual loss is compared to the estimated loss and any difference is recognized in net loss. Precious metals are included in other assets on the balance sheet.
Exploration and Evaluation Assets and Property, Plant and Equipment	Exploration and Evaluation Assets and Property, Plant and Equipment i) Cost Oil and gas properties and other property, plant and equipment are recorded at cost, including expenditures that are directly attributable to the purchase or development of an asset. Borrowing costs directly attributable to the acquisition, construction or production of a qualifying asset are included in the asset cost. Capitalization ceases when substantially all activities necessary to prepare the qualifying asset for its intended use are complete or when the construction and development of a project is suspended. ii) Exploration and Evaluation Costs The accounting treatment of costs incurred for oil and natural gas exploration, evaluation and development is determined by the classification of the underlying activities as either exploratory or developmental. The results from an exploration drilling program can take considerable time to analyze, and the determination that commercial reserves have been discovered requires determination of technical feasibility, commercial viability and industry experience. Exploration activities can fluctuate from year to year, due to such factors as the level of exploratory spending, the level of risk sharing with third parties participating in exploratory drilling and the degree of risk associated with drilling in particular areas. Properties that are assumed to be productive may, over a period of time, actually deliver oil and gas in quantities different than originally estimated because of changes in reservoir performance. Costs incurred after the legal right to explore an area has been obtained and before technical feasibility and commercial viability of the area have been established are capitalized as exploration and evaluation assets. These costs include costs to acquire acreage and exploration rights, legal and other professional fees and land brokerage fees. Pre-license costs and geological and geophysical costs associated with exploration activities are expensed in the period incurred. Costs directly associated with an exploration well are initially capitalized as an exploration and evaluation asset until the drilling of the well is complete and the results have been evaluated. If extractable hydrocarbons are found and are likely to be developed commercially, but are subject to further appraisal activity, which may include the drilling of wells, the costs continue to be carried as an exploration and evaluation asset while sufficient and continued progress is made in assessing the commercial viability of the hydrocarbons. Capitalized exploration and evaluation costs or assets are not depreciated and are carried forward until technical feasibility and commercial viability of the area is determined or the assets are determined to be impaired. Management determines technical feasibility and commercial viability when exploration and evaluation assets are reclassified to property, plant and equipment. This decision considers several factors, including the existence of reserves, establishing commercial and technical feasibility and whether the asset can be developed using a proved development concept and has received internal approval. Upon the determination of technical feasibility and commercial viability, capitalized exploration and evaluation assets are then transferred to property, plant and equipment. All such carried costs are subject to technical, commercial and management review, as well as review for impairment indicators, at least every reporting period to confirm the continued intent to develop or otherwise extract value from the discovery. These costs are also tested for impairment when transferred to property, plant and equipment. Capitalized exploration and evaluation expenditures related to wells that do not find reserves, or where no future activity is planned, are expensed as exploration and evaluation expenses. The application of the Company’s accounting policy for exploration and evaluation costs requires judgment in determining whether it is likely that future economic benefit exists when activities have not reached a stage where technical feasibility and commercial viability can be reasonably determined. Judgments may change as new information becomes available. iii) Development Costs Expenditures, including borrowing costs, on the construction, installation and completion of infrastructure facilities, such as platforms, pipelines and the drilling of development wells, are capitalized as oil and gas properties. Costs incurred to operate and maintain wells and equipment to lift oil and gas to the surface are expensed as production and operating expenses. iv) Other Property, Plant and Equipment Repair and maintenance costs, other than major turnaround costs, are expensed as incurred. Major turnaround costs are capitalized as part of property, plant and equipment when incurred and are amortized over the estimated period of time to the anticipated date of the next turnaround. v) Depletion, Depreciation and Amortization Oil and gas properties are depleted on a unit-of-production basis over the proved developed producing reserves of the particular field, except in the case of assets whose useful life is shorter or longer than the lifetime of the proved developed producing reserves of that field, in which case the straight-line method or a unit-of-production method based on total proved plus probable reserves is applied. The unit-of-production rate for the depletion of oil and gas properties related to total proved plus probable reserves takes into account expenditures incurred to date together with sanctioned future development expenditures required to develop the field. Oil and gas reserves are evaluated internally and audited by independent qualified reserve engineers. The estimation of reserves is an inherently complex process and involves the exercise of professional judgment. Estimates are based on projected future rates of production, estimated commodity prices, operating and royalty costs, engineering data and the estimated amount and timing of future expenditures, all of which are subject to uncertainty. Changes in reserve estimates can have an impact on reported net loss through revisions to depletion, depreciation and amortization expense, in addition to determining possible impairments and reversal of impairments of property, plant and equipment. Net reserves represent the Company's undivided gross working interest in total reserves after deducting crown, freehold and overriding royalty interests. Assumptions reflect market and regulatory conditions, as applicable, as at the balance sheet date and could differ significantly from other points in time throughout the year or future periods. Changes in market and regulatory conditions and assumptions can materially impact the estimation of net reserves. Depreciation for substantially all other property, plant and equipment is provided using the straight-line method based on the estimated useful lives of assets, which range from five to forty-five years. The useful lives of assets are estimated based upon the period the asset is expected to be available for use by the Company. Depletion, depreciation and amortization rates for all capitalized costs associated with the Company's activities are reviewed at least annually, or when events or conditions occur that impact capitalized costs, reserves and estimated service lives.
Joint Arrangements	Joint Arrangements Joint arrangements represent activities where the Company has joint control established by a contractual agreement. Joint control requires unanimous consent for financial and operational decisions. A joint arrangement is either a joint operation, whereby the parties have rights to the assets and obligations for the liabilities, or a joint venture, whereby the parties have rights to the net assets. For a joint operation, the consolidated financial statements include the Company’s proportionate share of the assets, liabilities, revenues, expenses and cash flows of the joint arrangement. The Company reports items of a similar nature to those on the financial statements of the joint arrangement, on a line-by-line basis, from the date that joint control commences until the date that joint control ceases. Joint ventures are accounted for using the equity method of accounting and recognized at cost and adjusted thereafter for the post-acquisition change in the Company’s share of the joint venture’s net assets. The Company’s consolidated financial statements include its share of the joint venture’s profit or loss and other comprehensive income (“OCI”) included in investment in joint ventures, until the date that joint control ceases. Classification of a joint arrangement as either joint operation or joint venture requires judgment. Management’s considerations include, but are not limited to, determining if the arrangement is structured through a separate vehicle and whether the legal form and contractual arrangements give the entity direct rights to the assets and obligations for the liabilities within the normal course of business. Other facts and circumstances are also assessed by management, including the entity’s rights to the economic benefits of assets and its involvement and responsibility for settling liabilities associated with the arrangement.
Business Combinations	Business CombinationsBusiness combinations are accounted for using the acquisition method. Determining whether an acquisition meets the definition of a business combination or represents an asset purchase requires judgment on a case-by-case basis. If the acquisition meets the definition of a business combination, the assets and liabilities are recognized based on the contractual terms, economic conditions, the Company’s operating and accounting policies and other factors that exist on the acquisition date, which is the date on which control is transferred to the Company. The identifiable assets and liabilities are measured at their fair values on the acquisition date with limited exceptions. Any additional consideration payable, contingent upon the occurrence of a future event, is recognized at fair value on the acquisition date; subsequent changes in the fair value of the liability are recognized in net loss. Acquisition costs incurred are expensed and included in selling, general and administrative expenses in the consolidated statements of loss.
Goodwill	GoodwillGoodwill is the excess of the purchase price paid over the recognized amount of net assets acquired through business combinations, which is inherently imprecise as judgment is required in the determination of the fair value of assets and liabilities. Goodwill, which is not amortized, is assigned to appropriate CGUs or groups of CGUs. Goodwill is tested for impairment annually and when circumstances indicate that the carrying value may be impaired. Impairment losses are recognized in net loss and are not subject to reversal. On the disposal or termination of a previously acquired business, any remaining balance of associated goodwill is included in the determination of the gain or loss on disposal.
Impairment and Reversals of Impairment on Non-Financial Assets	Impairment and Reversals of Impairment on Non-Financial Assets The carrying amounts of the Company’s non-financial assets, other than inventories and deferred tax assets but including right-of-use assets, are reviewed at the end of each reporting period to determine whether there is an indication of impairment or reversal of previously recorded impairment. If such indication exists, the recoverable amount is estimated. Determining whether there are any indications of impairment or impairment reversals requires significant judgment of external factors, such as an extended change in prices or margins for oil and gas commodities or refined products, a significant change in an asset’s market value, a significant revision of estimated volumes, revision of future development costs, a change in the entity’s market capitalization or significant changes in the technological, market, economic or legal environment that would have an impact on the Company’s CGUs. If any indication of impairment or impairment reversals exist, an estimate of the asset’s recoverable amount is calculated as the higher of the fair value less costs to sell (“FVLCS”) and the asset’s value in use (“VIU”) for an individual asset or CGU. If the asset does not generate cash inflows that are largely independent of those from other assets or groups of assets, the asset is tested as part of a CGU, which is the smallest identifiable group of assets, liabilities and associated goodwill that generates cash inflows that are largely independent of the cash inflows from other assets or groups of assets. Determination of the Company’s CGUs is subject to management’s judgment. FVLCS is the amount that would be obtained from the sale of a CGU in an arm’s length transaction between knowledgeable and willing parties. The FVLCS is generally determined as the net present value of the estimated future cash flows expected to arise from a CGU, including any expansion prospects, and its eventual disposal, using assumptions that an independent market participant may take into account. These cash flows are discounted using a rate that would be applied by a market participant to arrive at a net present value of the CGU, less cost to dispose. VIU is the net present value of the estimated future cash flows expected to arise from the continued use of the asset in its present form and its eventual disposal. VIU is determined by applying assumptions specific to the Company’s continued use and can only take into account sanctioned future development costs. Estimates of future cash flows used in the evaluation of impairment of assets are made using management’s forecasts of commodity prices, royalty rates, operating costs and future capital expenditures, forecasted crack spreads, growth rate, discount rate and, in the case of oil and gas properties, expected production volumes. Expected production volumes take into account assessments of field reservoir performance and include expectations about proved and probable volumes and where applicable economically recoverable resources associated with interests in certain Husky properties which are risk-weighted utilizing geological, production, recovery, market price and economic projections. Either the cash flow estimates or the discount rate is risk-adjusted to reflect local conditions as appropriate. Given that the calculations for recoverable amounts require the use of estimates and assumptions, including forecasts of commodity prices, marketing supply and demand, product margins and in the case of oil and gas properties, expected production volumes, it is possible that the assumptions may change, which may impact the estimated life of the CGU and may require a material adjustment to the carrying value of goodwill and non-financial assets. An impairment loss is recognized if the carrying amount of an asset or its CGU exceeds its estimated recoverable amount. Impairment losses recognized with respect to CGUs are allocated first to reduce the carrying amount of any goodwill allocated to the units and then to reduce the carrying amounts of the other assets in the CGU or group of CGUs on a pro rata basis. Impairment losses are recognized in depletion, depreciation, amortization and impairment in the consolidated statements of loss. Impairment losses recognized in prior years are assessed at the end of each reporting period for indications that the impairment has decreased or no longer exists. An impairment loss is reversed only to the extent that the carrying amount of the asset or CGU does not exceed the carrying amount that would have been determined, net of depletion, depreciation and amortization, if no impairment loss had been recognized.
Asset Retirement Obligations (ARO)	Asset Retirement Obligations (“ARO”) A liability is recognized for future legal or constructive retirement obligations associated with the Company’s assets. The Company has significant obligations to remove tangible assets and restore land after operations cease and the Company retires or relinquishes the asset. The retirement of Upstream and Downstream assets consists primarily of plugging and abandoning wells, abandoning surface and subsea plant and equipment and facilities and restoring land to a state required by regulation or contract. The amount recognized is the net present value of the estimated future expenditures determined in accordance with local conditions, current technology and current regulatory requirements. The obligation is calculated using the current estimated costs to retire the asset inflated to the estimated retirement date and then discounted using a credit-adjusted risk-free discount rate. The liability is recorded in the period in which an obligation arises with a corresponding increase to the carrying value of the related asset. The liability is progressively accreted over time as the effect of discounting unwinds, creating an expense recognized in finance expenses. The costs capitalized to the related assets are amortized in a manner consistent with the depletion, depreciation and amortization of the underlying assets. Actual retirement expenditures are charged against the accumulated liability as incurred. Liabilities for ARO are adjusted every reporting period for changes in estimates. These adjustments are accounted for as a change in the corresponding capitalized cost, except where a reduction in the provision is greater than the undepreciated capitalized cost of the related assets, in which case the capitalized cost is reduced to nil and the remaining adjustment is recognized in net loss. Changes to the amount of capitalized costs will result in an adjustment to future depletion, depreciation and amortization, and to finance expenses. Estimating the ARO requires significant judgment as restoration technologies and costs are constantly changing, as are regulatory, political, environmental and safety considerations. Inherent in the calculation of the ARO are numerous assumptions including the ultimate settlement amounts, future third-party pricing, inflation factors, risk-free discount rates, credit risk, timing of settlement and changes in the legal, regulatory, environmental and political environments. Future revisions to these assumptions may result in material changes to the ARO liability. Adjustments to the estimated amounts and timing of future ARO cash flows are a regular occurrence in light of the significant judgments and estimates involved.
Legal and Other Contingent Matters	Legal and Other Contingent MattersProvisions and liabilities for legal and other contingent matters are recognized in the period when the circumstance becomes probable that a future cash outflow resulting from past operations or events will occur and the amount of the cash outflow can be reasonably estimated. The timing of recognition and measurement of the provision requires the application of judgment to existing facts and circumstances, which can be subject to change, and the carrying amounts of provisions and liabilities are reviewed regularly and adjusted accordingly. The Company is required to both determine whether a loss is probable based on judgment and interpretation of laws and regulations, and determine that the loss can be reasonably estimated. When a loss is recognized, it is charged to net loss. The Company continually monitors known and potential contingent matters and makes appropriate disclosure and provisions when warranted by the circumstances present.
Financial Instruments	Financial Instruments Financial instruments are any contracts that give rise to a financial asset of one entity and a financial liability or equity instrument of another entity. Financial assets are classified in one of the following categories: subsequently measured at amortized cost, fair value through other comprehensive income (“FVTOCI”), or fair value through profit or loss (“FVTPL”). Financial liabilities are initially recognized at fair value, and subsequently measured based on classification in one of the following categories: subsequently measured at amortized cost and FVTPL. Financial assets and liabilities are not offset unless there is a currently enforceable legal right to offset the recognized amounts and there is an intention to settle on a net basis, to realize the assets and settle the liabilities simultaneously. Financial assets and liabilities subsequently measured at amortized costs are measured using the effective interest method. The effective interest method is a method of calculating the amortized costs of a financial liability and of allocating interest expense over the relevant period. Transaction costs that are directly attributable to the acquisition or issue of a financial instrument are measured at amortized cost and added to the fair value initially recognized. Financial instruments at FVTPL are stated at fair value, with any gains or losses arising on remeasurement recognized in profit or loss. Unrealized gains and losses on FVTPL financial instruments related to trading activities are recognized in marketing and other in the consolidated statements of loss, and unrealized gains and losses on all other FVTPL financial instruments are recognized in other - net. Transaction costs directly attributable to the acquisition of financial assets or liabilities at FVTPL are recognized immediately in net loss. Financial instruments at FVTOCI are stated at fair value, with any gains or losses arising on remeasurement recognized in OCI except for impairment gains or losses and foreign exchange gains and losses. Financial instruments subsequently revalued at fair value are further categorized using a three-level hierarchy that reflects the significance of the inputs used in determining fair value. Level 1 fair value is determined by reference to quoted prices in active markets for identical assets and liabilities. Level 2 fair value is based on inputs that are independently observable for similar assets or liabilities. Level 3 fair value is not based on independently observable market data. The disclosure of the fair value hierarchy excludes financial assets and liabilities where book value approximates fair value.
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities Derivatives are financial instruments for which the fair value changes in response to market risks, require little or no initial investment and are settled at a future date. Derivative instruments are utilized by the Company to manage various market risks including volatility in commodity prices, foreign exchange rates and interest rate exposures. The Company’s policy is not to utilize derivative instruments for speculative purposes. The Company may enter into swap and other derivative transactions to hedge or mitigate the Company’s commercial risk, including derivatives that reduce risks that arise in the ordinary course of the Company’s business. The Company may choose to apply hedge accounting to derivative instruments. The fair values of derivatives are determined using valuation models that require assumptions concerning the amount and timing of future cash flows and discount rates. These estimates are also subject to change with fluctuations in commodity prices, interest rates, foreign currency exchange rates and estimates of non-performance. When able, the Company will determine fair value by incorporating forward market prices and rates that are compared to quotes received from financial institutions to ensure reasonability. The actual settlement of a derivative instrument could differ materially from the fair value recorded and could impact future results. i) Derivative Instruments All derivative instruments, other than those designated as effective hedging instruments or certain non-financial derivative contracts that meet the Company’s own use requirements, are classified as FVTPL and are recorded at fair value. Gains and losses on these instruments are recorded in the consolidated statements of loss in the period they occur. The Company may enter into commodity price contracts in order to offset fixed or floating prices with market rates to manage exposures to fluctuations in commodity prices. The estimation of the fair value of commodity derivatives incorporates forward prices and adjustments for quality or location. The related inventory is measured at fair value based on exit prices. Gains and losses from these derivative contracts, which are not designated as effective hedging instruments, are recognized in revenues or purchases of crude oil and products and are initially recorded at settlement date. Derivative instruments that have been designated as effective hedging instruments are further classified as either fair value or cash flow hedges (see “Hedging Activities”). ii) Embedded Derivatives Derivatives embedded within a hybrid contract containing a financial asset host are not accounted for separately, rather the whole instrument is classified as FVTPL. Derivatives embedded in other hybrid contracts are recorded separately when the economic characteristics and risks of the embedded derivative are not clearly and closely related to those of the host contract and the host contract is not measured at FVTPL. The definition of an embedded derivative is the same as freestanding derivatives. Embedded derivatives are measured at fair value with gains and losses recognized in net loss. iii) Hedging Activities At the inception of a derivative transaction, if the Company elects to use hedge accounting, formal designation and documentation is required. The documentation must include: identification of the hedged item or transaction, the hedging instrument, the nature of the risk being hedged, the Company’s risk management objective and strategy for undertaking the hedge and how the Company will assess the hedging instrument’s effectiveness in offsetting the exposure to changes in the hedged item. A hedge is assessed at inception and at the end of each reporting period to ensure that it is highly effective in offsetting changes in fair values or cash flows of the hedged item. For a fair value hedge, the gain or loss from remeasuring the hedging instrument at fair value is recognized immediately in net loss with the offsetting gain or loss on the hedged item. When fair value hedge accounting is discontinued, the carrying amount of the hedging instrument is deferred and amortized to net loss over the remaining maturity of the hedged item. For a cash flow hedge, the effective portion of the gain or loss is recorded in OCI. Any hedge or portion of a hedge that is ineffective is immediately recognized in net loss. Hedge accounting is discontinued on a prospective basis when the hedging relationship no longer qualifies for hedge accounting. Any gain or loss on the hedging instrument resulting from the discontinuation of a cash flow hedge is deferred in OCI until the forecasted transaction date. If the forecasted transaction date is no longer expected to occur, the gain or loss is recognized in net loss in the period of discontinuation. A net investment hedge of a foreign operation is accounted for similarly to a cash flow hedge. The Company may designate certain U.S. dollar denominated debt as a hedge of its net investment in foreign operations for which the U.S. dollar is the functional currency. The unrealized foreign exchange gains and losses arising from the translation of the debt are recorded in OCI, net of tax, and are limited to the translation gain or loss on the net investment.
Impairment of Financial Assets	Impairment of Financial Assets A financial asset is assessed at the end of each reporting period to determine whether it is impaired, based on objective evidence indicating that one or more events have had a negative effect on the estimated future cash flows of that asset. Objective evidence used by the Company to assess impairment of financial assets includes quoted market prices for similar financial assets and historical collection rates. An impairment loss with respect to a financial asset measured at amortized cost is calculated as the difference between its carrying amount and the net present value of the estimated future cash flows discounted at the original effective interest rate, according to the expected credit loss model. Significant financial assets are tested for impairment on an individual basis. The remaining financial assets are assessed for lifetime expected credit losses collectively in groups that share similar credit risk characteristics. All impairment losses are recognized in net loss. An impairment loss is reversed if the reversal can be related objectively to an event occurring after the impairment loss was recognized. Given that the calculations for the net present value of estimated future cash flows related to derivative financial assets require the use of estimates and assumptions, including forecasts of commodity prices, marketing supply and demand, product margins and expected production volumes, it is possible that the assumptions may change, which may require a material adjustment to the carrying value of financial assets.
Description of accounting policy for employee benefits [text block]	Pensions and Other Post-employment Benefits The Company maintains various defined contribution and defined benefit pension plans for its employees. The cost of the pension benefits earned by employees in the defined contribution pension plans is expensed as incurred. The cost of the benefits earned by employees in the defined benefit pension plans is determined using the projected unit credit funding method. Actuarial gains and losses are recognized in retained earnings as incurred. The defined benefit asset or liability is comprised of the fair value of plan assets from which the obligations are to be settled and the present value of the defined benefit obligation. Plan assets are measured at fair value based on the closing bid price when there is a quoted price in an active market. Plan assets are assets that are held by a long-term employee benefit fund or qualifying insurance policies. Plan assets are not available to the Company’s creditors. The value of any defined benefit asset is restricted to the sum of any past service costs and the present value of refunds from and reductions in future contributions to the plan. Defined benefit obligations are estimated by discounting expected future payments using the year-end market rate of interest for high-quality corporate debt instruments with cash flows that match the timing and amount of expected benefit payments. Post-retirement medical benefits are also provided to qualifying retirees. In some cases the benefits are provided through medical care plans to which the Company, the employees, the retirees and covered family members contribute. In some plans there is no funding of the benefits before retirement. These plans are recognized on the same basis as described above for the defined benefit pension plan. The determination of the cost of the defined benefit pension plan and the other post-retirement benefit plans reflects a number of assumptions that affect the expected future benefit payments. The valuation of these plans is prepared by an independent actuary engaged by the Company. These assumptions include, but are not limited to, the estimate of expected plan investment performance, salary escalation, retirement age, attrition, future health care costs and mortality. The fair value of the plan assets is used for the purposes of calculating the expected return on plan assets The assumptions for each pension plan are reviewed each year and are adjusted where necessary to reflect changes in fund experience and actuarial recommendations. Mortality rates are based on the latest available standard mortality tables for the individual countries concerned. The rate of return on pension plan assets is based on a projection of real long-term bond yields and an equity risk premium, which are combined with local inflation assumptions and applied to the actual asset mix of each plan. The amount of the expected return on plan assets is calculated using the expected rate of return for the year and the fair value of assets at the beginning of the year. Future salary increases are based on expected future inflation rates for the individual countries.
Income Taxes	Income Taxes Current income tax is recognized in net loss in the period unless it relates to items recognized directly to equity, including OCI, in which case the deferred income tax is also recorded in equity. Management periodically evaluates positions taken in the Company’s tax returns with respect to situations in which applicable tax regulations are subject to interpretation and reassessment and establishes provisions where appropriate. Deferred tax is measured using the liability method on temporary differences at the reporting date between the tax bases of assets and liabilities and their carrying amounts for financial reporting purposes. Deferred tax assets and liabilities are recognized at expected tax rates in effect in the year when the asset is expected to be realized or the liability settled, based on tax rates and tax laws that have been enacted or substantively enacted at the reporting date. Deferred income tax balances are adjusted to reflect changes in income tax rates that are substantively enacted with the adjustment being recognized in net loss in the period that the change occurs unless it relates to items recognized directly to equity, including OCI, in which case the deferred income tax is also recorded in equity. Deferred tax assets and deferred tax liabilities are offset if a legally enforceable right exists to set off current tax assets against current income tax liabilities and the deferred taxes relate to the same taxable entity and the same taxation authority. The determination of the Company’s income and other tax liabilities requires interpretation of complex laws and regulations often involving multiple jurisdictions. Estimates that require significant judgments are also made with respect to the timing of temporary difference reversals, the realizability of tax assets and in circumstances where the transaction and calculations for which the ultimate tax determination are uncertain. All tax filings are subject to audit and potential reassessment after the lapse of considerable time. Accordingly, the actual income tax liability may differ significantly from that estimated and recorded by management.
Description of accounting policy for non-monetary transactions [Policy Text Block]	Asset Exchange TransactionsAsset exchange transactions are measured at cost if the transaction lacks commercial substance or the fair value of neither the asset received nor the asset given up is reliably measurable. Otherwise, asset exchange transactions are measured at the fair value of the asset given up, unless the fair value of the asset received is more clearly evident. If the acquired item is not measured at fair value, its cost is measured at the carrying amount of the asset given up. Gains and losses are recorded in other - net in the consolidated statements of loss in the period they occur.
Revenue Recognition	Revenue Recognition Revenue is recognized when the performance obligations are satisfied, and revenue can be reliably measured. Revenue is measured at the consideration specified in the contract and represents amounts receivable for goods or services provided in the normal course of business, net of discounts, customs duties and sales taxes. The Company has no obligation for returns, refunds, warranties or similar obligations. Royalties are recognized as a reduction to gross revenues. The Company generates revenue from the following material products and services; • Sale of crude oil, bitumen, natural gas, NGLs and synthetic crude; • Crude oil and natural gas processing services; • Pipeline transportation, the blending of crude oil and natural gas and the storage of crude oil, diluent and natural gas; • Sale of refined petroleum products such as gasoline, diesel, ethanol blended fuels, asphalt and ancillary products, and production of ethanol; and • Construction services. Performance obligations are satisfied on the sale of crude oil, bitumen, natural gas, NGLs, synthetic crude, and refined products such as gasoline, diesel, ancillary retail products, ethanol blended fuels, asphalt, ancillary refined products, and the production of ethanol at the point in time when the products are delivered to and the title passes to the customer. Whereas the performance obligations are satisfied on the provision of services for crude oil and natural gas processing services, pipeline transportation, the blending of crude oil and natural gas, and the storage of crude oil, diluent and natural gas at the point in time when the services are provided. All sales prices are floating based upon market rates or contracted amounts, including long-term fixed pricing for Asia-Pacific natural gas. Sales, services and royalties are billed and paid on a weekly or monthly basis. Physical exchanges of inventory are recognized as non-monetary exchanges and are reported on a net basis for swaps of similar items, as are sales and purchases made with a common counterparty as part of an arrangement similar to a physical exchange. Under take-or-pay contracts, the Company makes a long-term supply commitment in return for a commitment from the buyer to pay for minimum quantities, whether or not the customer takes the delivery. If a buyer has a right to get a ‘make-up’ delivery at a later date the performance obligation is not satisfied, and revenue is deferred and recognized only when the product is delivered, or the ‘make-up’ provision can no longer be made. Determining when the ‘make-up’ product can no longer be taken, or how much can no longer be taken, requires estimates of future deliveries. Changes in these estimates may result in a material difference in deferred revenue recognized. If no such option exists within the contractual terms, the performance obligation is satisfied, and revenue is recognized when the take-or-pay is triggered. Construction revenue relates to general contractor services provided to HMLP of which the Company owns 35%. The Company acts as a general contractor for fixed price and cost-plus contracts. Revenue from fixed price contracts is recognized as performance obligations are met. Revenue from cost plus contracts are recognized as services are performed. Construction services are billed and paid monthly, or upon the completion of the project.
Foreign Currency	Foreign Currency Functional currency is the currency of the primary economic environment in which the Company and its subsidiaries operate and is normally the currency in which the entity primarily generates and expends cash. The financial statements of Husky’s subsidiaries are translated into Canadian dollars, which is the presentation and functional currency of the Company. The assets and liabilities of subsidiaries whose functional currencies are other than Canadian dollars are translated into Canadian dollars at the foreign exchange rate at the balance sheet date, while revenues and expenses of such subsidiaries are translated using average monthly foreign exchange rates, which approximate the foreign exchange rates on the dates of the transactions. Foreign exchange differences arising on translation are included in OCI. The Company’s transactions in foreign currencies are translated to the appropriate functional currency at the foreign exchange rate on the dates of the transactions. Monetary assets and liabilities denominated in foreign currencies are translated to the functional currency at the foreign exchange rate at the balance sheet date and differences arising on translation are recognized in net loss. Non-monetary assets that are measured in terms of historical cost in a foreign currency are translated using the exchange rate at the dates of the transactions.
Share-based Payments	Share-based Payments In accordance with the Company’s stock option plan, stock options to acquire common shares may be granted to officers and certain other employees. The Company records compensation expense over the vesting period based on the fair value of options granted. Compensation expense is recorded in net loss as part of selling, general and administrative expenses. The Company’s stock option plan is a tandem plan that provides the stock option holder with the right to exercise the stock option or surrender the option for a cash payment. A liability for the stock options is accrued over their vesting period and measured at fair value using the Black-Scholes option pricing model. The liability is revalued each reporting period until it is settled to reflect changes in the fair value of the options. The net change is recognized in net loss. When stock options are surrendered for cash, the cash settlement paid reduces the outstanding liability. When stock options are exercised for common shares, consideration paid by the stock option holders and the previously recognized liability associated with the stock options are recorded as share capital. The Company’s Performance Share Unit Plan provides a time-vested award to certain officers and employees of the Company. Performance Share Units (“PSU”) entitle participants to receive cash based on the Company’s share price at the time of vesting. The amount of cash payment is contingent on the Company’s total shareholder return relative to a peer group of companies and achieving a return on capital in use (“ROCIU”) target. ROCIU equals net loss plus after-tax interest expense divided by the two-year average capital employed, less any capital invested in assets that are not in use. Net loss is adjusted for the difference between actual realized and budgeted commodity prices and foreign exchange rates and other actual and budgeted exceptional items. A liability for expected cash payments is accrued over the vesting period of the PSUs and is revalued at each reporting date based on the market price of the Company’s common shares and the expected vesting percentage. Upon vesting, a cash payment is made to the participants and the outstanding liability is reduced by the payment amount.
Earnings per Share	Loss per shareThe number of basic common shares outstanding is the weighted average number of common shares outstanding for each period. Shares issued during the period are included in the weighted average number of shares from the date consideration is received. The calculation of basic loss per common share is based on net loss attributable to common shareholders divided by the weighted average number of common shares outstanding.The number of diluted common shares outstanding is calculated using the treasury stock method, which assumes that any proceeds received from in-the-money stock options would be used to buy back common shares at the average market price for the period. The calculation of diluted loss per share is based on net loss attributable to common shareholders divided by the weighted average number of common shares outstanding adjusted for the effects of all potential dilutive common share issuances, which are comprised of common shares issuable upon exercise of stock options granted to employees. Stock options granted to employees provide the holder with the ability to settle in cash or equity. For the purposes of the diluted loss per share calculation, the Company must adjust the numerator for the more dilutive effect of cash-settlement versus equity-settlement despite how the stock options are accounted for in net loss. As a result, net loss reported based on accounting of cash-settled stock options may be adjusted for the results of equity-settlements for the purposes of determining the numerator for the diluted loss per share calculation.
Government Grants	Government GrantsGovernment grants are recognized when there is reasonable assurance that the grant will be received and all attached conditions will be complied with. If a grant is received but reasonable assurance and compliance with conditions is not achieved, the grant is recognized as a deferred liability until such conditions are fulfilled. When the grant relates to an expense item, it is recognized as income in the period in which the costs are incurred. Where the grant relates to an asset, it is recognized as a reduction to the net book value of the related asset and recognized in net loss in equal amounts over the expected useful life of the related asset through lower depletion, depreciation and amortization.
Description of accounting policy for transactions with related parties [text block]	Related Party Judgments and Estimates The Company entered into transactions and agreements in the normal course of business with certain related parties, joint
Recent Accounting Standards	Recent Accounting StandardsThe Company has not early adopted any standard, interpretation or amendment that has been issued but is not yet effective.
Changes in Accounting Policy	Change in Accounting PolicyThe Company has not adopted any changes to material accounting policies during the fiscal year ended December 31, 2020.

Description of Business and S_2

Description of Business and Segmented Disclosures (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure of notes and other explanatory information [Abstract]
Disclosure of entity's operating segments [text block]	Segmented Financial Information Integrated Corridor ($ millions) Lloydminster Heavy Oil Value Chain (1) Oil Sands Western Canada Production U.S. Refining Years ended December 31, 2020 2019 2020 2019 2020 2019 2020 2019 Gross revenues (3) 3,753 5,601 306 649 367 514 6,636 10,253 Royalties (92) (160) (2) (13) (10) (41) — — Marketing and other (3) 22 52 (48) 4 15 99 40 23 Revenues, net of royalties 3,683 5,493 256 640 372 572 6,676 10,276 Expenses Purchases of crude oil and products (3) 1,827 2,395 153 246 22 40 6,500 8,934 Production, operating and transportation expenses (3) 1,059 1,212 114 140 250 313 797 872 Selling, general and administrative expenses 204 155 24 27 64 106 72 51 Depletion, depreciation, amortization and impairment 2,058 941 1,749 938 802 1,034 4,419 735 Exploration and evaluation expenses 182 54 (1) 2 1 111 — — Loss (gain) on sale of assets (4) — — — (20) (2) — 1 Other – net (3) 21 9 (26) (28) (7) 1 (84) (654) 5,347 4,766 2,013 1,325 1,112 1,603 11,704 9,939 Earnings (loss) from operating activities (1,664) 727 (1,757) (685) (740) (1,031) (5,028) 337 Share of equity investment income (loss) (32) 9 — — — — — — Financial items Net foreign exchange gain — — — — — — — — Finance income — — — — — — — — Finance expenses (47) (48) (57) (59) (19) (24) (18) (18) (47) (48) (57) (59) (19) (24) (18) (18) Earnings (loss) before income taxes (1,743) 688 (1,814) (744) (759) (1,055) (5,046) 319 Provisions for (recovery of) income taxes Current — (2) — 10 — — — 17 Deferred (434) 186 (452) (209) (189) (283) (1,121) 54 (434) 184 (452) (199) (189) (283) (1,121) 71 Net earnings (loss) (1,309) 504 (1,362) (545) (570) (772) (3,925) 248 (1) Includes $110 million of revenue (2019 - $201 million) and $99 million of associated costs (2019 - $269 million) for construction contracts in progress with revenue recognized as performance obligations are met. (2) Eliminations relate to sales and operating revenues between segments recorded at transfer prices based on current market prices. Segment results include transactions between business segments. (3) Results for certain items in the consolidated statements of loss reported for 2019 have been recast to reflect various reclassifications due to a change in presentation of the Integrated Corridor and Offshore business units. Segmented Financial Information Con’t Integrated Corridor Offshore Corporate Total Canadian Refined Products Eliminations (2) Total 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 1,488 2,425 (602) (948) 11,948 18,494 1,515 1,553 — — 13,463 20,047 — — — — (104) (214) (87) (109) — — (191) (323) — — — — 29 178 — — — — 29 178 1,488 2,425 (602) (948) 11,873 18,458 1,428 1,444 — — 13,301 19,902 1,349 2,175 (602) (948) 9,249 12,842 32 (16) — — 9,281 12,826 65 153 — — 2,285 2,690 275 340 — — 2,560 3,030 44 9 — — 408 348 75 55 262 290 745 693 62 83 — — 9,090 3,731 3,738 1,661 92 104 12,920 5,496 — — — — 182 167 551 380 — — 733 547 — (6) — — (24) (7) (1) (1) — — (25) (8) (4) — — — (100) (672) (5) 1 (157) (16) (262) (687) 1,516 2,414 (602) (948) 21,090 19,099 4,665 2,420 197 378 25,952 21,897 (28) 11 — — (9,217) (641) (3,237) (976) (197) (378) (12,651) (1,995) — — — — (32) 9 39 50 — — 7 59 — — — — — — — — 14 44 14 44 — — — — — — 7 3 18 71 25 74 (11) (13) — — (152) (162) (41) (38) (206) (151) (399) (351) (11) (13) — — (152) (162) (34) (35) (174) (36) (360) (233) (39) (2) — — (9,401) (794) (3,232) (961) (371) (414) (13,004) (2,169) — — — — — 25 150 125 52 25 202 175 (10) — — — (2,206) (252) (963) (393) (21) (329) (3,190) (974) (10) — — — (2,206) (227) (813) (268) 31 (304) (2,988) (799) (29) (2) — — (7,195) (567) (2,419) (693) (402) (110) (10,016) (1,370) Segmented Financial Information Integrated Corridor ($ millions) Lloydminster Heavy Oil Value Chain Oil Sands Western Canada Production Years ended December 31, 2020 2019 2020 2019 2020 2019 Expenditures on exploration and evaluation assets (1) — 17 — — — 3 Expenditures on property, plant and equipment (1) 594 939 9 38 57 191 As at December 31, Exploration and evaluation assets — 154 — — — 2 Developing and producing assets at cost 15,212 15,453 3,021 3,104 12,849 13,300 Accumulated depletion, depreciation, amortization and impairment (11,411) (10,345) (2,498) (1,020) (12,207) (11,764) Other property, plant and equipment at cost 4,189 3,820 76 3 55 62 Accumulated depletion, depreciation and amortization (2,752) (2,410) (9) — (30) (40) Total exploration and evaluation assets and property, plant and equipment, net 5,238 6,672 590 2,087 667 1,560 Total right-of-use assets, net 68 54 167 430 4 9 Total assets 6,650 8,312 993 2,757 707 1,709 (1) Excludes capitalized costs related to asset retirement obligations and capitalized interest incurred during the year. Includes assets acquired through acquisition, but excludes assets acquired through corporate acquisition. Geographical Financial Information ($ millions) Canada United States Years ended December 31, 2020 2019 2020 2019 Gross revenues (1)(2) 5,648 8,734 6,636 10,253 Royalties (122) (263) — — Marketing and other (2) (11) 155 40 23 Revenue, net of royalties 5,515 8,626 6,676 10,276 As at December 31, Restricted cash – non-current — — — — Exploration and evaluation assets — 599 — — Property, plant and equipment, net 7,893 14,630 2,868 6,053 Right-of-use assets, net 616 1,044 81 156 Goodwill — — — 656 Investment in joint ventures — 666 — — Long-term income tax receivable 202 212 — — Deferred tax assets 1,127 — 187 — Other assets (3) 30 47 119 458 Total non-current assets 9,868 17,198 3,255 7,323 (1) Sales to external customers are based on the location of the seller. (2) Results reported for 2019 have been recast to reflect various reclassifications due to a change in presentation of the Integrated Corridor and Offshore business units. (3) Includes insurance proceeds of $98 million (2019 - $435 million), related to the Superior Refinery incident. Segmented Financial Information Con’t Integrated Corridor Offshore Corporate Total U.S. Refining Canadian Refined Products Eliminations Total 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 — — — — — — — 20 1 26 — — 1 46 489 768 5 73 — — 1,154 2,009 367 1,246 65 131 1,586 3,386 — — — — — — — 156 46 487 — — 46 643 — — — — — — 31,082 31,857 15,102 14,730 — — 46,184 46,587 — — — — — — (26,116) (23,129) (11,773) (8,219) — — (37,889) (31,348) 10,057 9,540 1,287 1,284 — — 15,664 14,709 7 7 1,388 1,377 17,059 16,093 (7,190) (3,488) (794) (743) — — (10,775) (6,681) — — (1,083) (1,028) (11,858) (7,709) 2,867 6,052 493 541 — — 9,855 16,912 3,382 7,005 305 349 13,542 24,266 82 157 102 122 — — 423 772 3 138 272 292 698 1,202 4,469 8,645 625 838 — — 13,444 22,261 4,570 8,077 1,673 2,784 19,687 33,122 Geographical Financial Information Con’t China Other International Total 2020 2019 2020 2019 2020 2019 1,179 1,060 — — 13,463 20,047 (69) (60) — — (191) (323) — — — — 29 178 1,110 1,000 — — 13,301 19,902 164 142 — — 164 142 41 39 5 5 46 643 2,735 2,938 — 2 13,496 23,623 1 2 — — 698 1,202 — — — — — 656 — — 457 516 457 1,182 — — — — 202 212 — — 14 — 1,328 — — — 17 19 166 524 2,941 3,121 493 542 16,557 28,184 Disaggregation of Revenue Integrated Corridor ($ millions) Lloydminster Heavy Oil Value Chain Oil Sands Western Canada Production U.S. Refining Years ended December 31, 2020 2019 2020 2019 2020 2019 2020 2019 Primary Geographical Markets Canada 3,753 5,601 306 649 367 514 — — United States — — — — — — 6,636 10,253 China — — — — — — — — Total revenue 3,753 5,601 306 649 367 514 6,636 10,253 Major Product Lines (1) Synthetic crude oil 981 1,495 — — — — — — Gasoline — — — — — — 3,453 5,414 Diesel & distillates 170 260 — — — — 2,282 3,644 Asphalt 475 609 — — — — 85 136 Total upgraded and refined products 1,626 2,364 — — — — 5,820 9,194 Diluted bitumen — — 308 640 — — — — Blended crude oil 1,500 2,197 — — — — — — Light & medium crude oil — — — — 82 167 — — NGL — — — — 101 168 — — Natural gas — — — — 153 162 — — Total unrefined products 1,500 2,197 308 640 336 497 — — Other 627 1,040 (2) 9 31 17 816 1,059 Total revenue 3,753 5,601 306 649 367 514 6,636 10,253 (1) Results reported for 2019 have been recast to reflect a change in reclassification of intersegment sales eliminations and a change in presentation of the Integrated Corridor and Offshore business units. Disaggregation of Revenue Con’t Integrated Corridor Offshore Corporate Total Canadian Refined Products Eliminations Total 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 1,488 2,425 (602) (948) 5,312 8,241 336 493 — — 5,648 8,734 — — — — 6,636 10,253 — — — — 6,636 10,253 — — — — — — 1,179 1,060 — — 1,179 1,060 1,488 2,425 (602) (948) 11,948 18,494 1,515 1,553 — — 13,463 20,047 — — — — 981 1,495 — — — — 981 1,495 620 904 — — 4,073 6,318 — — — — 4,073 6,318 793 1,152 — — 3,245 5,056 — — — — 3,245 5,056 — — — — 560 745 — — — — 560 745 1,413 2,056 — — 8,859 13,614 — — — — 8,859 13,614 — — — — 308 640 — — — — 308 640 — — — — 1,500 2,197 — — — — 1,500 2,197 — — — — 82 167 336 493 — — 418 660 — — — — 101 168 152 182 — — 253 350 — — — — 153 162 1,026 875 — — 1,179 1,037 — — — — 2,144 3,334 1,514 1,550 — — 3,658 4,884 75 369 — — 1,547 2,494 1 3 — — 1,548 2,497 1,488 2,425 (602) (948) 11,948 18,494 1,515 1,553 — — 13,463 20,047

Accounts Receivable (Tables)

Accounts Receivable (Tables)	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Accounts Receivable	Accounts Receivable ($ millions) December 31, 2020 December 31, 2019 Trade receivables 773 1,327 Provision for expected credit losses (36) (34) Derivatives due within one year 33 38 Other (1) 349 168 End of year 1,119 1,499 (1) Includes insurance proceeds of $312 million (2019 - $114 million), related to the Superior Refinery incident.

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Schedule of Inventories	Inventories ($ millions) December 31, 2020 December 31, 2019 Crude oil, natural gas and NGL 409 627 Refined petroleum products 411 553 Trading inventories measured at fair value less costs to sell 121 155 Materials, supplies and other 174 151 End of year 1,115 1,486

Exploration and Evaluation Co_2

Exploration and Evaluation Costs (Tables)	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Disclosure of detailed information about exploration and evaluation assets	Exploration and Evaluation Assets ($ millions) 2020 2019 Beginning of year 643 997 Additions 1 46 Transfers to property, plant and equipment ( note 9 ) (3) (44) Expensed exploration expenditures previously capitalized (594) (355) Exchange adjustments (1) (1) End of year 46 643 Property, Plant and Equipment Oil and Gas Properties Processing, Upgrading Refining Retail and Other Total ($ millions) Cost December 31, 2018 44,196 101 2,659 10,691 3,095 60,742 Transfers to right-of-use assets (1) (note 10) (336) — — (180) — (516) Additions 2,340 2 58 899 160 3,459 Acquisitions 10 — — — — 10 Transfers from exploration and evaluation (note 8) 44 — — — — 44 Transfers from right-of-use assets (2) (note 10) 101 — — — — 101 Intersegment transfers 2 — — 27 (29) — Changes in asset retirement obligations (note 18) 469 1 5 19 23 517 Disposals and derecognition (16) (2) (1) (943) (2) (964) Exchange adjustments (223) (1) — (496) (2) (722) December 31, 2019 46,587 101 2,721 10,017 3,245 62,671 Additions 852 — 216 502 70 1,640 Acquisitions 1 — — — — 1 Transfers from exploration and evaluation (note 8) 3 — — — — 3 Transfers from right-of-use assets (2) (note 10) 4 — — — — 4 Intersegment transfers 18 41 — — (59) — Changes in asset retirement obligations (note 18) (530) — (13) (51) (33) (627) Disposals and derecognition (419) (2) — (12) (2) (435) Exchange adjustments (80) (3) — 64 (1) (20) December 31, 2020 46,436 137 2,924 10,520 3,220 63,237 Accumulated depletion, depreciation, amortization and impairment December 31, 2018 (27,379) (50) (1,585) (3,933) (1,995) (34,942) Transfers to right-of-use assets (1) (note 10) 12 — — 40 — 52 Depletion, depreciation, amortization and impairment (4,082) (2) (115) (736) (239) (5,174) Intersegment transfers — — — (17) 17 — Disposals and derecognition 8 — — 724 2 734 Exchange adjustments 93 1 — 187 1 282 December 31, 2019 (31,348) (51) (1,700) (3,735) (2,214) (39,048) Depletion, depreciation, amortization and impairment (7,083) (46) (90) (3,644) (228) (11,091) Intersegment transfers (9) — — — 9 — Disposals and derecognition 380 12 — — 1 393 Exchange adjustments 47 1 — (44) 1 5 December 31, 2020 (38,013) (84) (1,790) (7,423) (2,431) (49,741) Net book value December 31, 2019 15,239 50 1,021 6,282 1,031 23,623 December 31, 2020 8,423 53 1,134 3,097 789 13,496
Disclosure of exploration and evaluation expenses	The following exploration and evaluation expenses for the years ended December 31, 2020 and 2019 relate to activities associated with the exploration for and evaluation of crude oil and natural gas resources and were recorded in the Integrated Corridor and Offshore business segments. Exploration and Evaluation Expense Summary (1) ($ millions) 2020 2019 Seismic, geological and geophysical 117 131 Expensed drilling 612 409 Expensed land 4 7 733 547

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Disclosure of detailed information about property, plant and equipment	Exploration and Evaluation Assets ($ millions) 2020 2019 Beginning of year 643 997 Additions 1 46 Transfers to property, plant and equipment ( note 9 ) (3) (44) Expensed exploration expenditures previously capitalized (594) (355) Exchange adjustments (1) (1) End of year 46 643 Property, Plant and Equipment Oil and Gas Properties Processing, Upgrading Refining Retail and Other Total ($ millions) Cost December 31, 2018 44,196 101 2,659 10,691 3,095 60,742 Transfers to right-of-use assets (1) (note 10) (336) — — (180) — (516) Additions 2,340 2 58 899 160 3,459 Acquisitions 10 — — — — 10 Transfers from exploration and evaluation (note 8) 44 — — — — 44 Transfers from right-of-use assets (2) (note 10) 101 — — — — 101 Intersegment transfers 2 — — 27 (29) — Changes in asset retirement obligations (note 18) 469 1 5 19 23 517 Disposals and derecognition (16) (2) (1) (943) (2) (964) Exchange adjustments (223) (1) — (496) (2) (722) December 31, 2019 46,587 101 2,721 10,017 3,245 62,671 Additions 852 — 216 502 70 1,640 Acquisitions 1 — — — — 1 Transfers from exploration and evaluation (note 8) 3 — — — — 3 Transfers from right-of-use assets (2) (note 10) 4 — — — — 4 Intersegment transfers 18 41 — — (59) — Changes in asset retirement obligations (note 18) (530) — (13) (51) (33) (627) Disposals and derecognition (419) (2) — (12) (2) (435) Exchange adjustments (80) (3) — 64 (1) (20) December 31, 2020 46,436 137 2,924 10,520 3,220 63,237 Accumulated depletion, depreciation, amortization and impairment December 31, 2018 (27,379) (50) (1,585) (3,933) (1,995) (34,942) Transfers to right-of-use assets (1) (note 10) 12 — — 40 — 52 Depletion, depreciation, amortization and impairment (4,082) (2) (115) (736) (239) (5,174) Intersegment transfers — — — (17) 17 — Disposals and derecognition 8 — — 724 2 734 Exchange adjustments 93 1 — 187 1 282 December 31, 2019 (31,348) (51) (1,700) (3,735) (2,214) (39,048) Depletion, depreciation, amortization and impairment (7,083) (46) (90) (3,644) (228) (11,091) Intersegment transfers (9) — — — 9 — Disposals and derecognition 380 12 — — 1 393 Exchange adjustments 47 1 — (44) 1 5 December 31, 2020 (38,013) (84) (1,790) (7,423) (2,431) (49,741) Net book value December 31, 2019 15,239 50 1,021 6,282 1,031 23,623 December 31, 2020 8,423 53 1,134 3,097 789 13,496

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Disclosure of quantitative information about right-of-use assets [text block]	Right-of-use Assets Oil and Gas Properties Processing, Upgrading Refining Retail and Other Total ($ millions) January 1, 2019 Transfers from property, plant and equipment (note 9) 324 — — 140 — 464 Initial recognition 721 100 — 70 412 1,303 1,045 100 — 210 412 1,767 Additions 1 — — 80 5 86 Transfers to property, plant and equipment (note 9) (101) — — — — (101) Disposals and derecognition (11) — — (31) 2 (40) Revaluation (194) 1 — (1) 8 (186) Depreciation and impairment (222) (11) — (50) (39) (322) Other 2 — — (4) — (2) December 31, 2019 520 90 — 204 388 1,202 Additions 5 6 — 15 4 30 Transfers to property, plant and equipment (note 9) (4) — — — — (4) Disposals and derecognition (3) — — — — (3) Revaluation — 16 — 11 — 27 Depreciation and impairment (399) (11) — (91) (53) (554) Other 1 (1) — — — — December 31, 2020 120 100 — 139 339 698 Results of Operations ($ millions) December 31, 2020 December 31, 2019 Interest expense on lease liabilities (note 22) 97 106 Expenses relating to short-term leases 13 18 Cash Flow Summary ($ millions) December 31, 2020 December 31, 2019 Total cash flow used for leases 208 339
Disclosure of additional information about leasing activities for lessee [text block]	Balance Sheets ($ millions) December 31, 2020 December 31, 2019 Current lease liabilities 102 109 Non-current lease liabilities 1,298 1,353

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Disclosure of reconciliation of changes in goodwill	Goodwill ($ millions) December 31, 2020 December 31, 2019 Beginning of year (1) 656 690 Exchange adjustments 13 (34) Impairment (note 9) (669) — End of year — 656

Joint Arrangements (Tables)

Joint Arrangements (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure of joint ventures [line items]
Disclosure of joint operations	The following table lists the Company’s significant subsidiaries and jointly-controlled entities and their respective places of incorporation, continuance or organization, as the case may be, and the Company’s percentage equity interest (to the nearest whole number) as at December 31, 2020. All of the entities listed below, except as otherwise indicated, are 100% beneficially owned, or controlled or directed, directly or indirectly, by the Company. Significant Subsidiaries and Joint Operations % Jurisdiction Husky Oil Operations Limited 100 Alberta Husky Energy International Corporation 100 Alberta Lima Refining Company 100 Delaware Husky Marketing and Supply Company 100 Delaware Husky Oil Limited Partnership 100 Alberta Husky Canadian Petroleum Marketing Partnership 100 Alberta Husky Energy Marketing Partnership 100 Alberta Sunrise Oil Sands Partnership 50 Alberta BP-Husky Refining LLC 50 Delaware
Husky-CNOOC Madura Ltd.
Disclosure of joint ventures [line items]
Disclosure of joint ventures	Summarized below is the financial information for Husky-CNOOC Madura Ltd. accounted for using the equity method: Results of Operations ($ millions, except share of equity investment) 2020 2019 Revenues 386 424 Expenses (280) (267) Net earnings 106 157 Share of equity investment 40 % 40 % Proportionate share of equity investment 39 50 Balance Sheets ($ millions, except share of equity investment) December 31, 2020 December 31, 2019 Current assets (1) 215 208 Non-current assets 1,657 1,840 Current liabilities (77) (70) Non-current liabilities (2) (1,160) (1,427) Net assets 635 551 Share of net assets 40 % 40 % Carrying amount in balance sheet 457 516 (1) Includes cash and cash equivalents of $48 million (2019 – $42 million). (2) Includes deferred revenue of $8 million (2019 - $nil) related to take-or-pay commitments, with respect to natural gas production volumes from the BD Project, not taken by the purchaser. As per the terms of the agreement, the purchaser has until the end of the agreement to take these volumes.

Other Assets (Tables)

Other Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Miscellaneous non-current assets [abstract]
Schedule of other assets	Other Assets ($ millions) December 31, 2020 December 31, 2019 Long-term receivables (1) 130 489 Precious metals 21 22 Other 15 13 End of year 166 524 (1) Includes insurance proceeds o f $98 million ( 2019 – $435 million), related to the Superior Refinery incident. For the year ended December 31, 2020, the Company accrued pre-tax recoveries for rebuild costs, incident costs and business interruption associated with the Superior Refinery incident of $85 million (December 31, 2019 - $630 million), which is included in other-net in the consolidated statements of loss.

Accounts Payable and Accrued _2

Accounts Payable and Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Schedule of accounts payable and accrued liabilities	Accounts Payable and Accrued Liabilities ($ millions) December 31, 2020 December 31, 2019 Trade payables 772 1,178 Accrued liabilities 1,115 1,954 Dividend payable (note 20) 13 126 Stock-based compensation 22 19 Derivatives due within one year 31 21 Other 176 167 End of year 2,129 3,465

Debt and Credit Facilities (Tab

Debt and Credit Facilities (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure of borrowing costs [Abstract]
Schedule of short-term debt	Short-term Debt December 31, 2020 December 31, 2019 ($ millions) Commercial paper (1) — 550 Bankers' Acceptances 40 —
Schedule of long-term debt	Canadian $ Amount U.S. $ Denominated Long-term Debt Maturity December 31, 2020 December 31, 2019 December 31, 2020 December 31, 2019 ($ millions) Long-term debt Syndicated Credit Facility 2022 350 — — — 3.95% notes (1)(3) 2022 637 648 500 500 4.00% notes (1)(3) 2024 957 973 750 750 3.55% notes (4) 2025 750 750 — — 3.60% notes (4) 2027 750 750 — — 3.50% notes (4) 2028 1,250 — — — 4.40% notes (1)(3) 2029 957 973 750 750 6.80% notes (1)(3) 2037 493 501 387 387 Debt issue costs (2) (27) (25) — — Long-term debt 6,117 4,570 2,387 2,387 Long-term debt due within one year 5.00% notes (4) 2020 — 400 — — Long-term debt due within one year — 400 — — (1) The U.S. dollar denominated debt is designated as a hedge of the Company’s net investment in selected foreign operations with a U.S. dollar functional currency. Refer to Note 25 for Foreign Currency Risk Management. (2) Calculated using the effective interest rate method. (3) The 3.95%, the 4.00%, the 4.40% and the 6.80% notes represent unsecured securities under a trust indenture dated September 11, 2007.
Reconciliation of changes of liabilities to cash flows from financing activities	Reconciliation of Changes of Liabilities to Cash Flows from Financing Activities Liabilities ($ millions) Short-term debt Long-term debt due within one year Long-term debt Other long-term liabilities Lease liabilities due within one year Lease liabilities December 31, 2019 550 400 4,570 454 109 1,353 Changes from financing cash flows Long-term debt issuance, net — (1,400) 2,600 — — — Short-term debt issuance, net (510) — — — — — Debt issue costs — — (7) — — — Finance lease payments — — — — (111) — Total change from financing cash flows (510) (1,400) 2,593 — (111) — Other changes – liability-related Foreign exchange — — — (1) — — Fair value changes — — — 8 — 32 Net additions of lease liabilities — — — — — 23 Reclassification — 1,000 (1,000) — 107 (107) Deferred revenue — — — (115) — — Amortization of debt issuance costs — — 4 — — — Foreign exchange recognized in OCI — — (50) — (1) (2) Other — — — 64 (2) (1) Total other changes – liability related — 1,000 (1,046) (44) 104 (55) December 31, 2020 40 — 6,117 410 102 1,298

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Reconciliation of the carrying amount of asset retirement obligations	A reconciliation of the carrying amount of asset retirement obligations at December 31, 2020 and 2019 is set out below: Asset Retirement Obligations ($ millions) 2020 2019 Beginning of year 2,755 2,424 Additions 63 76 Liabilities settled (39) (276) Liabilities disposed (39) (6) Change in discount rate (544) 285 Change in estimates (146) 156 Exchange adjustment 8 (10) Accretion (note 22) 104 106 End of year 2,162 2,755 Expected to be incurred within 1 year 94 112 Expected to be incurred beyond 1 year 2,068 2,643

Other Long-term Liabilities (Ta

Other Long-term Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Schedule of other long-term liabilities	Other Long-term Liabilities ($ millions) December 31, 2020 December 31, 2019 Employee future benefits (note 23) 233 214 Stock-based compensation 19 19 Deferred revenue 37 152 Other 121 69 End of year 410 454
Schedule of Deferred Revenue [Table Text Block]	Deferred revenue Deferred revenue relates to take-or-pay commitments, with respect to natural gas production volumes from the Liwan 3-1 field in Asia Pacific, not taken by the purchaser. As per the terms of the agreement, the purchaser has until the end of the agreement to take these volumes. ($ millions) December 31, 2020 December 31, 2019 Beginning of year 152 205 Revenue recognized (115) (42) Exchange adjustment — (11) End of year 37 152

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure of income tax [Abstract]
Disclosure of income tax expense (recovery)	The major components of income tax expense (recovery) for the years ended December 31, 2020 and 2019 were as follows: Income Tax Expense (Recovery) ($ millions) 2020 2019 Current income tax Current income tax charge 183 174 Adjustments to current income tax estimates 19 1 202 175 Deferred income tax Relating to origination and reversal of temporary differences (3,248) (723) Adjustments to deferred income tax estimates 58 (251) (3,190) (974)
Disclosure of deferred tax items in OCI	Deferred Tax Items in OCI ($ millions) 2020 2019 Deferred tax items expensed (recovered) directly in OCI Derivatives designated as cash flow hedges (3) (3) Remeasurement of pension plans (2) 1 Exchange differences on translation of foreign operations 29 (58) Hedge of net investment 6 30 30 (30)
Disclosure of reconciliation of effective tax rate	The provision for income taxes in the consolidated statements of loss reflects an effective tax rate which differs from the expected statutory tax rate. Differences for the years ended December 31, 2020 and 2019 were as follows: Reconciliation of Effective Tax Rate ($ millions, except tax rate) 2020 2019 Earnings (loss) before income taxes Canada (8,799) (3,170) United States (4,969) 337 Other foreign jurisdictions 764 664 (13,004) (2,169) Statutory Canadian income tax rate 24.9 % 26.8 % Expected income tax (3,238) (582) Effect on income tax resulting from: Capital gains and losses 1 — Foreign jurisdictions 202 61 Non-taxable items (16) (25) Adjustments with respect to previous year 77 (250) Revaluation of foreign tax pools (12) (4) Other – net (2) 1 Income tax recovery (2,988) (799)
Disclosure of deferred tax liabilities and assets	The following reconciles the movements in the deferred income tax liabilities and assets: Deferred Tax Liabilities and Assets ($ millions) January 1, 2020 Recognized in Loss Recognized in OCI December 31, 2020 Deferred tax liabilities Exploration and evaluation assets and property, plant and equipment (3,053) 2,578 (14) (489) Foreign exchange gains taxable on realization (150) 151 (4) (3) Debt issue costs (5) — — (5) Financial assets at fair value (9) 2 — (7) Other temporary differences (152) 51 — (101) Deferred tax assets Pension plans 16 10 2 28 Asset retirement obligations 666 (138) (2) 526 Loss carry-forwards 517 536 (12) 1,041 (2,170) 3,190 (30) 990 Deferred Tax Liabilities and Assets ($ millions) January 1, 2019 Recognized in Loss Recognized in OCI December 31, 2019 Deferred tax liabilities Exploration and evaluation assets and property, plant and equipment (4,089) 967 69 (3,053) Foreign exchange gains taxable on realization (174) 51 (27) (150) Debt issue costs (4) (1) — (5) Other temporary differences (28) (124) — (152) Financial assets at fair value (9) — — (9) Deferred tax assets Pension plans 8 9 (1) 16 Asset retirement obligations 654 16 (4) 666 Loss carry-forwards 468 56 (7) 517 (3,174) 974 30 (2,170)

Share Capital (Tables)

Share Capital (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure of share capital, reserves and other equity interest [Abstract]
Disclosure of classes of share capital	The Company is authorized to issue an unlimited number of no par value common shares. Common Shares Number of Shares Amount ($ millions) December 31, 2018, 2019 and 2020 1,005,121,738 7,293 Quarterly dividends may be declared in an amount expressed in dollars per common share or could be paid by way of issuance of a fraction of a common share per outstanding common share determined by dividing the dollar amount of the dividend by the volume-weighted average trading price of the Common Shares on the principal stock exchange on which the common shares are traded. The volume-weighted average trading price of the common shares is calculated by dividing the total value by the total volume of common shares traded over the five trading day period immediately prior to the payment date of the dividend on the common shares. Common Share Dividends ($ millions) 2020 2019 Declared Paid Declared Paid 163 276 503 503 The Company is authorized to issue an unlimited number of no par value preferred shares. Cumulative Redeemable Preferred Shares Number of Shares Amount ($ millions) December 31, 2018, 2019 and 2020 36,000,000 874 Cumulative Redeemable Preferred Shares Dividends ($ millions) 2020 2019 Declared Paid Declared Paid Series 1 Preferred Shares 6 6 6 6 Series 2 Preferred Shares 1 1 1 1 Series 3 Preferred Shares 12 12 12 12 Series 5 Preferred Shares 9 9 9 9 Series 7 Preferred Shares 7 7 7 7 35 35 35 35 The following options to purchase common shares have been awarded to officers and certain other employees: Outstanding and Exercisable Options 2020 2019 Number of Options (thousands) Weighted Average ($) Number of Options (thousands) Weighted Average ($) Outstanding, beginning of year 18,498 17.75 19,967 21.48 Granted (1) 6,113 2.86 4,241 14.31 Surrendered for cash — — (4) 15.67 Expired or forfeited (5,728) 20.78 (5,706) 28.27 Outstanding, end of year 18,883 12.01 18,498 17.75 Exercisable, end of year 9,651 16.11 10,596 19.27 (1) Options granted during the year ended December 31, 2020 were attributed a fair value of $0.36 per option (December 31, 2019 – $2.34) at grant date. Outstanding and Exercisable Options Outstanding Options Exercisable Options Range of Exercise Price Number of Options (thousands) Weighted Average Exercise Prices ($) Weighted Average (years) Number of Options (thousands) Weighted Average Exercise Prices ($) $2.77 - $8.00 5,650 2.85 4.17 — — $8.01 - $15.92 6,085 14.88 1.92 3,802 15.22 $15.93 - $21.87 7,148 16.80 1.69 5,849 16.70 December 31, 2020 18,883 12.01 2.51 9,651 16.11 Black-Scholes Assumptions December 31, 2020 December 31, 2019 Tandem Tandem Dividend per option 0.21 0.42 Range of expected volatilities used (percent) 47.2 - 90.2 27.5 - 35.5 Range of risk-free interest rates used (percent) 0.06 - 0.39 1.66 - 1.74 Expected life of share options from vesting date (years) 1.99 1.97 Expected forfeiture rate (percent) 8.6 8.8 Weighted average exercise price 13.71 18.19 Weighted average fair value 0.87 0.25 The number of PSUs outstanding was as follows: Performance Share Units 2020 2019 Beginning of year 14,318,642 11,606,644 Granted 10,828,280 7,673,960 Exercised (2,111,552) (2,429,816) Forfeited (3,735,485) (2,532,146) Outstanding, end of year 19,299,885 14,318,642 Vested, end of year 4,621,999 3,264,840 Loss per Share ($ millions) 2020 2019 Net loss (10,016) (1,370) Effect of dividends declared on preferred shares in the year (35) (35) Net loss – basic (10,051) (1,405) Dilutive effect of accounting for stock options 4 (15) Net loss – diluted (10,047) (1,420) (millions) Weighted average common shares outstanding – basic 1,005.1 1,005.1 Weighted average common shares outstanding – diluted 1,005.1 1,005.1 Loss per share – basic ($/share) (10.00) (1.40) Loss per share – diluted ($/share) (10.00) (1.41)

Production, Operating and Tra_2

Production, Operating and Transportation and Selling, General, and Administrative Expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Analysis of income and expense [abstract]
Disclosure of production, operating and transportation expenses	The following table summarizes production, operating and transportation expenses in the consolidated statements of loss for the years ended December 31, 2020 and 2019: Production, Operating and Transportation Expenses ($ millions) 2020 2019 Services and support costs 1,119 1,255 Salaries and benefits 576 773 Materials, equipment rentals and leases 191 250 Energy and utility 476 482 Licensing fees 160 204 Transportation 18 17 Other 20 49 Total production, operating and transportation expenses (1) 2,560 3,030
Disclosure of general and administrative expense	The following table summarizes selling, general and administrative expenses in the consolidated statements of loss for the years ended December 31, 2020 and 2019: Selling, General and Administrative Expenses ($ millions) 2020 2019 Employee costs (1) 443 450 Stock-based compensation expense (recovery) (2) 16 (2) Contract services 128 133 Equipment rentals and leases 16 11 Maintenance and other 142 101 Total selling, general and administrative expenses 745 693 (1) Employee costs are comprised of salary and benefits earned during the year, plus cash bonuses awarded during the year. Annual bonus awards settled in shares are included in stock-based compensation expense.

Financial Items (Tables)

Financial Items (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure of additional information [Abstract]
Schedule of financial items	Financial Items ($ millions) 2020 2019 Foreign exchange gain Non-cash working capital 7 17 Other foreign exchange 7 27 Net foreign exchange gain 14 44 Finance income 25 74 Finance expenses Long-term debt (251) (310) Lease liabilities (note 10) (97) (106) Other (7) (6) (355) (422) Interest capitalized (1) 60 177 (295) (245) Accretion of asset retirement obligations (note 18) (104) (106) Finance expenses (399) (351) Total Financial Items (360) (233) (1) Interest capitalized on project costs is calculated using the Company’s annualized effective interest rate of 3% (2019 – 5%).

Pensions and Other Post-emplo_2

Pensions and Other Post-employment Benefits (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure of employee benefits [Abstract]
Disclosure of net benefit obligation	Defined Benefit Obligations DB Pension Plans OPEB Plans ($ millions) 2020 2019 2020 2019 Beginning of year 39 79 201 199 Current service cost — — 9 10 Interest cost 1 2 6 7 Benefits paid (2) (3) (5) (4) Past service cost — 3 — (29) Settlements — (49) — — Remeasurements Actuarial gain – experience — — (1) (1) Actuarial loss – financial assumptions 4 9 14 20 Effect of changes in foreign exchange rates (1) (2) — (1) End of year 41 39 224 201 Fair Value of Plan Assets DB Pension Plans OPEB Plans ($ millions) 2020 2019 2020 2019 Beginning of year 31 71 — — Contributions by employer — (1) 3 2 Benefits paid (2) (3) (3) (2) Interest income 1 2 — — Return on plan assets greater than discount rate 3 16 — — Settlements — (52) — — Effect of changes in foreign exchange rates (1) (2) — — End of year 32 31 — — Funded status DB Pension Plans OPEB Plans ($ millions) 2020 2019 2020 2019 Net liability (9) (8) (224) (201)
Disclosure of pension plan assets	The composition of the DB Pension Plan assets at December 31, 2020 and 2019 was as follows: DB Pension Plan Assets (percent) Target allocation 2020 2019 Money market type funds — — — Equity securities 35 35 35 Debt securities 65 65 65
Disclosure of a defined benefit amount recognized in net earnings and OCI	The following table summarizes amounts recognized in net loss and OCI for the DB Pension Plans and the OPEB Plans for the years ended December 31, 2020 and 2019: DB Pension Plans OPEB Plans ($ millions) 2020 2019 2020 2019 Amounts recognized in net loss Current service cost — — 9 10 Past service cost — 3 — (29) Net Interest cost — — 6 7 Benefit cost — 3 15 (12) Remeasurements Actuarial gain due to liability experience — — (1) (1) Actuarial loss due to liability assumption changes 4 9 14 20 Gain on plan assets (3) (16) — — Remeasurement effects recognized in OCI 1 (7) 13 19
Disclosure of actuarial assumptions and sensitivity analysis	The following long-term assumptions were used to estimate the value of the defined benefit obligations, the plan assets and the OPEB Plans: Assumptions DB Pension Plans OPEB Plans (percent) 2020 2019 2020 2019 Discount rate for benefit expense and obligation 0.8 - 3.2 2.3 - 4.2 2.5 - 3.2 3.0 -3.7 Rate of compensation expense 3.5 3.5 N/A N/A The sensitivity of the defined benefit and OPEB obligations to changes in relevant actuarial assumption is shown below: Sensitivity Analysis DB Pension Plans OPEB Plans ($ millions) 1% increase 1% decrease 1% increase 1% decrease Discount rate (5) 6 (25) 31 Health care cost trend rate N/A N/A 25 (22)

Cash Flows - Change in Non-ca_2

Cash Flows - Change in Non-cash Working Capital (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure of cash flow statement [Abstract]
Disclosure Of Changes In Non-Cash Working Capital	Non-cash Working Capital ($ millions) 2020 2019 Decrease (increase) in non-cash working capital Accounts receivable 724 (176) Inventories 377 (502) Prepaid expenses (14) (30) Accounts payable and accrued liabilities (1,152) 604 Change in non-cash working capital (65) (104) Relating to: Operating activities 347 (280) Financing activities 11 3 Investing activities (423) 173

Financial Instruments and Ris_2

Financial Instruments and Risk Management (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure of financial instruments by type of interest rate [line items]
Disclosure of financial instruments that are carried at fair value	The following table summarizes the Company’s financial instruments that are carried at fair value in the consolidated balance sheets: Financial Instruments at Fair Value ($ millions) December 31, 2020 December 31, 2019 Commodity contracts – FVTPL Natural gas (1) 33 31 Crude oil (2) 8 11 Crude oil call options (3) (23) (2) Crude oil put options (3) 8 (4) Foreign currency contracts – FVTPL Foreign currency forwards — 2 Other assets – FVTPL 1 1 End of year 27 39 (1) Natural gas contracts includes a $25 million increase at December 31, 2020 (December 31, 2019 – $4 million decrease) to the fair value of held-for-trading inventory, recognized in the consolidated balance sheets, related to third party physical purchase and sale contracts for natural gas held in storage. Total fair value of the related natural gas storage inventory was $37 million at December 31, 2020 (December 31, 2019 – $19 million). (2) Crude oil contracts includes a $5 million increase at December 31, 2020 (December 31, 2019 – $12 million increase) to the fair value of held-for-trading inventory, recognized in the consolidated balance sheets, related to third party crude oil physical purchase and sale contracts. Total fair value of the related crude oil inventory wa s $84 million at December 31, 2020 (December 31, 2019 – $136 million). (3) Excludes net unsettled premiums of $12 million.
Disclosure of offsetting of financial assets and financial liabilities [text block]	The tables below outline the financial assets and financial liabilities that are subject to set-off rights and related arrangements, and the effect of those rights and arrangements on the consolidated balance sheets: As at December 31, 2020 Offsetting Financial Assets and Liabilities ($ millions) Gross Amount Amount Offset Net Amount Financial Assets Financial derivatives 69 (51) 18 Normal purchase and sale agreements 391 (311) 80 End of year 460 (362) 98 Financial Liabilities Financial derivatives (116) 87 (29) Normal purchase and sale agreements (540) 307 (233) End of year (656) 394 (262) As at December 31, 2019 Offsetting Financial Assets and Liabilities ($ millions) Gross Amount Amount Offset Net Amount Financial Assets Financial derivatives 79 (26) 53 Normal purchase and sale agreements 817 (274) 543 End of year 896 (300) 596 Financial Liabilities Financial derivatives (48) 25 (23) Normal purchase and sale agreements (843) 281 (562) End of year (891) 306 (585)
Disclosure of nature and extent of risks arising from financial instruments [text block]	Commodity Price Risk (1) ($ millions) 10% price increase 10% price decrease Crude oil price (8) 8 Natural gas price (2) 2 (1) Based on average crude oil and natural gas market prices as at December 31, 2020.
Analysis of age of financial assets that are past due but not impaired [text block]	The Company’s accounts receivable was aged as follows at December 31, 2020: Accounts Receivable Aging ($ millions) December 31, 2020 Current 1,076 Past due (1 – 30 days) 63 Past due (31 – 60 days) 4 Past due (61 – 90 days) 3 Past due (more than 90 days) 9 Provision for expected credit losses (36) 1,119
Disclosure of available credit facilities	Bank Operating Loans At December 31, 2020, the Company had unsecured short-term borrowing lines of credit with banks totaling $975 million (1) (December 31, 2019 – $900 million) and letters of credit under these lines of credit totaling $427 million (December 31, 2019 – $436 million). As at December 31, 2020, bank operating loans were $40 million (December 31, 2019 – $nil). Interest payable is based on Bankers’ Acceptance, CAD Prime Rate, U.S. LIBOR, or U.S. Base Rates. Sunrise Oil Sands Partnership has an unsecured demand credit facility of $10 million (December 31, 2019 – $10 million) available for general purposes. The Company’s proportionate share of the credit facility is $5 million (December 31, 2019 – $5 million). As at December 31, 2020, there was no balance outstanding under this credit facility (December 31, 2019 – no balance). (1) Includes $125 million demand facilities available specifically for letters of credit only. The Company had the following available credit facilities as at December 31, 2020: Credit Facilities ($ millions) Available Unused Operating facilities (1) (note 15) 975 508 Syndicated bank facilities (2) (note 17) 4,000 3,650 End of year 4,975 4,158 (1) Consists of demand credit facilities. (2) Commercial paper outstanding is supported by the Company’s Syndicated credit facilities.
Interest rate swap contract [member]
Disclosure of financial instruments by type of interest rate [line items]
Disclosure of fair value of financial instruments [text block]

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure of related party [Abstract]
Related party transaction	The following table lists the Company’s significant subsidiaries and jointly-controlled entities and their respective places of incorporation, continuance or organization, as the case may be, and the Company’s percentage equity interest (to the nearest whole number) as at December 31, 2020. All of the entities listed below, except as otherwise indicated, are 100% beneficially owned, or controlled or directed, directly or indirectly, by the Company. Significant Subsidiaries and Joint Operations % Jurisdiction Husky Oil Operations Limited 100 Alberta Husky Energy International Corporation 100 Alberta Lima Refining Company 100 Delaware Husky Marketing and Supply Company 100 Delaware Husky Oil Limited Partnership 100 Alberta Husky Canadian Petroleum Marketing Partnership 100 Alberta Husky Energy Marketing Partnership 100 Alberta Sunrise Oil Sands Partnership 50 Alberta BP-Husky Refining LLC 50 Delaware
Disclosure of transactions between related parties	Key management includes Directors (executive and non-executive), Executive Officers and Senior Vice Presidents of the Company. The amounts disclosed in the table below are the amounts recognized as an expense during the reporting period related to key management personnel: Compensation of Key Management Personnel ($ millions) 2020 2019 Short-term employee benefits (1) 15 18 Stock-based compensation (2) 15 26 30 44 (1) Short-term employee benefits are comprised of salary and benefits earned during the year, plus cash bonuses awarded during the year. Annual bonus awards settled in shares are included in stock-based compensation expense. (2) Stock-based compensation expense represents the cost to the Company for participation in share-based payment plans.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies [Abstract]
Minimum Future Payments For Commitments	At December 31, 2020, the Company had commitments that require the following minimum future payments, which are not accrued in the consolidated balance sheets: Minimum Future Payments for Commitments ($ millions) Within 1 year After 1 year but not more than 5 years More than 5 years Total Operating agreements (1) 97 381 525 1,003 Firm transportation agreements (1)(4) 552 2,396 4,473 7,421 Unconditional purchase obligations (2) 1,766 3,327 3,324 8,417 Lease rentals and exploration work agreements 74 244 838 1,156 Obligations to fund equity investee (3) 54 319 280 653 2,543 6,667 9,440 18,650 (1) Included in operating agreements and firm transportation agreements are blending and storage agreements and transportation commitments of $1.2 billion and $1.7 billion respectively with HMLP. (2) Includes processing services, distribution services, insurance premiums, drilling services, natural gas purchases and the purchase of refined petroleum products. (3) Equity investee refers to the Company’s investment in Husky-CNOOC Madura Ltd. joint venture, which is accounted for under the equity method for consolidated financial statement purposes .

Description of Business and S_3

Description of Business and Segmented Disclosures - Income Statement (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of operating segments [line items]
Revenue from sale of goods	$ 13,463	$ 20,047
Royalties	(191)	(323)
Marketing and Other Contra Revenue Items	29	178
Revenues, net of royalties	13,301	19,902
Purchases of crude oil and products(1)	9,281	12,826
Production, operating and transportation expenses(1) (note 21)	2,560	3,030
Selling, general and administrative expenses (note 21)	745	693
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	12,920	5,496
Expense arising from exploration for and evaluation of mineral resources	733	547
Gains (losses) on disposals of property, plant and equipment	25	8
Other – net(1) (notes 14, 25, 26)	(262)	(687)
Expenses	25,952	21,897
Earnings from operating activities	(12,651)	(1,995)
Share of equity investment income (note 12)	7	59
Net foreign exchange gain	14	44
Finance income	25	74
Finance expenses	(399)	(351)
Financial Items	(360)	(233)
Earnings before income taxes	(13,004)	(2,169)
Current tax expense (income) and adjustments for current tax of prior periods	202	175
Deferred tax expense (income)	(3,190)	(974)
Tax expense (income)	(2,988)	(799)
Net loss	(10,016)	(1,370)
Revenue from sale of goods	13,463	20,047
Revenue	13,301	19,902
Expenses	25,952	21,897
Earnings from operating activities	(12,651)	(1,995)
Financial Items	(360)	(233)
Earnings before income taxes	(13,004)	(2,169)
Tax expense (income)	(2,988)	(799)
Net loss	(10,016)	(1,370)
Royalty expense	191	323
Marketing and Other Contra Revenue Items	(29)	(178)
Purchases of crude oil and products(1)	9,281	12,826
Production, operating and transportation expenses(1) (note 21)	2,560	3,030
Selling, general and administrative expenses (note 21)	745	693
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	12,920	5,496
Expense arising from exploration for and evaluation of mineral resources	733	547
Gains (losses) on disposals of property, plant and equipment	25	8
Other – net(1) (notes 14, 25, 26)	(262)	(687)
Share of equity investment income (note 12)	7	59
Net foreign exchange gain	14	44
Finance income	25	74
Finance costs	399	351
Provisions for (recovery of) income taxes. current	202	175
Deferred tax expense (income)	(3,190)	(974)
Operating Segments, Integrated Corridor [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods	11,948	18,494
Royalties	(104)	(214)
Marketing and Other Contra Revenue Items	29	178
Revenues, net of royalties	11,873	18,458
Purchases of crude oil and products(1)	9,249	12,842
Production, operating and transportation expenses(1) (note 21)	2,285	2,690
Selling, general and administrative expenses (note 21)	408	348
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	9,090	3,731
Expense arising from exploration for and evaluation of mineral resources	182	167
Gains (losses) on disposals of property, plant and equipment	24	7
Other – net(1) (notes 14, 25, 26)	(100)	(672)
Expenses	21,090	19,099
Earnings from operating activities	(9,217)	(641)
Share of equity investment income (note 12)	(32)	9
Net foreign exchange gain	0	0
Finance income	0	0
Finance expenses	(152)	(162)
Financial Items	(152)	(162)
Earnings before income taxes	(9,401)	(794)
Current tax expense (income) and adjustments for current tax of prior periods	0	25
Deferred tax expense (income)	(2,206)	(252)
Tax expense (income)	(2,206)	(227)
Net loss	(7,195)	(567)
Revenue from sale of goods	11,948	18,494
Revenue	11,873	18,458
Expenses	21,090	19,099
Earnings from operating activities	(9,217)	(641)
Financial Items	(152)	(162)
Earnings before income taxes	(9,401)	(794)
Tax expense (income)	(2,206)	(227)
Net loss	(7,195)	(567)
Royalty expense	104	214
Marketing and Other Contra Revenue Items	(29)	(178)
Purchases of crude oil and products(1)	9,249	12,842
Production, operating and transportation expenses(1) (note 21)	2,285	2,690
Selling, general and administrative expenses (note 21)	408	348
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	9,090	3,731
Expense arising from exploration for and evaluation of mineral resources	182	167
Gains (losses) on disposals of property, plant and equipment	24	7
Other – net(1) (notes 14, 25, 26)	(100)	(672)
Share of equity investment income (note 12)	(32)	9
Net foreign exchange gain	0	0
Finance income	0	0
Finance costs	152	162
Provisions for (recovery of) income taxes. current	0	25
Deferred tax expense (income)	(2,206)	(252)
Operating Segments, Integrated Corridor [Member] | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods	3,753	5,601
Royalties	(92)	(160)
Marketing and Other Contra Revenue Items	22	52
Revenues, net of royalties	3,683	5,493
Purchases of crude oil and products(1)	1,827	2,395
Production, operating and transportation expenses(1) (note 21)	1,059	1,212
Selling, general and administrative expenses (note 21)	204	155
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	2,058	941
Expense arising from exploration for and evaluation of mineral resources	182	54
Gains (losses) on disposals of property, plant and equipment	4	0
Other – net(1) (notes 14, 25, 26)	21	9
Expenses	5,347	4,766
Earnings from operating activities	(1,664)	727
Share of equity investment income (note 12)	(32)	9
Net foreign exchange gain	0	0
Finance income	0	0
Finance expenses	(47)	(48)
Financial Items	(47)	(48)
Earnings before income taxes	(1,743)	688
Current tax expense (income) and adjustments for current tax of prior periods	0	(2)
Deferred tax expense (income)	(434)	186
Tax expense (income)	(434)	184
Net loss	(1,309)	504
Revenue from construction contracts	110	201
Costs of construction contracts	99	269
Revenue from sale of goods	3,753	5,601
Revenue	3,683	5,493
Expenses	5,347	4,766
Earnings from operating activities	(1,664)	727
Financial Items	(47)	(48)
Earnings before income taxes	(1,743)	688
Tax expense (income)	(434)	184
Net loss	(1,309)	504
Royalty expense	92	160
Marketing and Other Contra Revenue Items	(22)	(52)
Purchases of crude oil and products(1)	1,827	2,395
Production, operating and transportation expenses(1) (note 21)	1,059	1,212
Selling, general and administrative expenses (note 21)	204	155
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	2,058	941
Expense arising from exploration for and evaluation of mineral resources	182	54
Gains (losses) on disposals of property, plant and equipment	4	0
Other – net(1) (notes 14, 25, 26)	21	9
Share of equity investment income (note 12)	(32)	9
Net foreign exchange gain	0	0
Finance income	0	0
Finance costs	47	48
Provisions for (recovery of) income taxes. current	0	(2)
Deferred tax expense (income)	(434)	186
Costs of construction contracts	99	269
Operating Segments, Integrated Corridor [Member] | Oil Sands [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods	306	649
Royalties	(2)	(13)
Marketing and Other Contra Revenue Items	(48)	4
Revenues, net of royalties	256	640
Purchases of crude oil and products(1)	153	246
Production, operating and transportation expenses(1) (note 21)	114	140
Selling, general and administrative expenses (note 21)	24	27
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	1,749	938
Expense arising from exploration for and evaluation of mineral resources	(1)	2
Gains (losses) on disposals of property, plant and equipment	0	0
Other – net(1) (notes 14, 25, 26)	(26)	(28)
Expenses	2,013	1,325
Earnings from operating activities	(1,757)	(685)
Share of equity investment income (note 12)	0	0
Net foreign exchange gain	0	0
Finance income	0	0
Finance expenses	(57)	(59)
Financial Items	(57)	(59)
Earnings before income taxes	(1,814)	(744)
Current tax expense (income) and adjustments for current tax of prior periods	0	10
Deferred tax expense (income)	(452)	(209)
Tax expense (income)	(452)	(199)
Net loss	(1,362)	(545)
Revenue from sale of goods	306	649
Revenue	256	640
Expenses	2,013	1,325
Earnings from operating activities	(1,757)	(685)
Financial Items	(57)	(59)
Earnings before income taxes	(1,814)	(744)
Tax expense (income)	(452)	(199)
Net loss	(1,362)	(545)
Royalty expense	2	13
Marketing and Other Contra Revenue Items	48	(4)
Purchases of crude oil and products(1)	153	246
Production, operating and transportation expenses(1) (note 21)	114	140
Selling, general and administrative expenses (note 21)	24	27
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	1,749	938
Expense arising from exploration for and evaluation of mineral resources	(1)	2
Gains (losses) on disposals of property, plant and equipment	0	0
Other – net(1) (notes 14, 25, 26)	(26)	(28)
Share of equity investment income (note 12)	0	0
Net foreign exchange gain	0	0
Finance income	0	0
Finance costs	57	59
Provisions for (recovery of) income taxes. current	0	10
Deferred tax expense (income)	(452)	(209)
Operating Segments, Integrated Corridor [Member] | Western Canada Production [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods	367	514
Royalties	(10)	(41)
Marketing and Other Contra Revenue Items	15	99
Revenues, net of royalties	372	572
Purchases of crude oil and products(1)	22	40
Production, operating and transportation expenses(1) (note 21)	250	313
Selling, general and administrative expenses (note 21)	64	106
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	802	1,034
Expense arising from exploration for and evaluation of mineral resources	1	111
Gains (losses) on disposals of property, plant and equipment	20	2
Other – net(1) (notes 14, 25, 26)	(7)	1
Expenses	1,112	1,603
Earnings from operating activities	(740)	(1,031)
Share of equity investment income (note 12)	0	0
Net foreign exchange gain	0	0
Finance income	0	0
Finance expenses	(19)	(24)
Financial Items	(19)	(24)
Earnings before income taxes	(759)	(1,055)
Current tax expense (income) and adjustments for current tax of prior periods	0	0
Deferred tax expense (income)	(189)	(283)
Tax expense (income)	(189)	(283)
Net loss	(570)	(772)
Revenue from sale of goods	367	514
Revenue	372	572
Expenses	1,112	1,603
Earnings from operating activities	(740)	(1,031)
Financial Items	(19)	(24)
Earnings before income taxes	(759)	(1,055)
Tax expense (income)	(189)	(283)
Net loss	(570)	(772)
Royalty expense	10	41
Marketing and Other Contra Revenue Items	(15)	(99)
Purchases of crude oil and products(1)	22	40
Production, operating and transportation expenses(1) (note 21)	250	313
Selling, general and administrative expenses (note 21)	64	106
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	802	1,034
Expense arising from exploration for and evaluation of mineral resources	1	111
Gains (losses) on disposals of property, plant and equipment	20	2
Other – net(1) (notes 14, 25, 26)	(7)	1
Share of equity investment income (note 12)	0	0
Net foreign exchange gain	0	0
Finance income	0	0
Finance costs	19	24
Provisions for (recovery of) income taxes. current	0	0
Deferred tax expense (income)	(189)	(283)
Operating Segments, Integrated Corridor [Member] | U.S Refining [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods	6,636	10,253
Royalties	0	0
Marketing and Other Contra Revenue Items	40	23
Revenues, net of royalties	6,676	10,276
Purchases of crude oil and products(1)	6,500	8,934
Production, operating and transportation expenses(1) (note 21)	797	872
Selling, general and administrative expenses (note 21)	72	51
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	4,419	735
Expense arising from exploration for and evaluation of mineral resources	0	0
Gains (losses) on disposals of property, plant and equipment	0	(1)
Other – net(1) (notes 14, 25, 26)	(84)	(654)
Expenses	11,704	9,939
Earnings from operating activities	(5,028)	337
Share of equity investment income (note 12)	0	0
Net foreign exchange gain	0	0
Finance income	0	0
Finance expenses	(18)	(18)
Financial Items	(18)	(18)
Earnings before income taxes	(5,046)	319
Current tax expense (income) and adjustments for current tax of prior periods	0	17
Deferred tax expense (income)	(1,121)	54
Tax expense (income)	(1,121)	71
Net loss	(3,925)	248
Revenue from sale of goods	6,636	10,253
Revenue	6,676	10,276
Expenses	11,704	9,939
Earnings from operating activities	(5,028)	337
Financial Items	(18)	(18)
Earnings before income taxes	(5,046)	319
Tax expense (income)	(1,121)	71
Net loss	(3,925)	248
Royalty expense	0	0
Marketing and Other Contra Revenue Items	(40)	(23)
Purchases of crude oil and products(1)	6,500	8,934
Production, operating and transportation expenses(1) (note 21)	797	872
Selling, general and administrative expenses (note 21)	72	51
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	4,419	735
Expense arising from exploration for and evaluation of mineral resources	0	0
Gains (losses) on disposals of property, plant and equipment	0	(1)
Other – net(1) (notes 14, 25, 26)	(84)	(654)
Share of equity investment income (note 12)	0	0
Net foreign exchange gain	0	0
Finance income	0	0
Finance costs	18	18
Provisions for (recovery of) income taxes. current	0	17
Deferred tax expense (income)	(1,121)	54
Operating Segments, Integrated Corridor [Member] | Canadian Refined Products [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods	1,488	2,425
Royalties	0	0
Marketing and Other Contra Revenue Items	0	0
Revenues, net of royalties	1,488	2,425
Purchases of crude oil and products(1)	1,349	2,175
Production, operating and transportation expenses(1) (note 21)	65	153
Selling, general and administrative expenses (note 21)	44	9
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	62	83
Expense arising from exploration for and evaluation of mineral resources	0	0
Gains (losses) on disposals of property, plant and equipment	0	(6)
Other – net(1) (notes 14, 25, 26)	(4)	0
Expenses	1,516	2,414
Earnings from operating activities	(28)	11
Share of equity investment income (note 12)	0	0
Net foreign exchange gain	0	0
Finance income	0	0
Finance expenses	(11)	(13)
Financial Items	(11)	(13)
Earnings before income taxes	(39)	(2)
Current tax expense (income) and adjustments for current tax of prior periods	0	0
Deferred tax expense (income)	(10)	0
Tax expense (income)	(10)	0
Net loss	(29)	(2)
Revenue from sale of goods	1,488	2,425
Revenue	1,488	2,425
Expenses	1,516	2,414
Earnings from operating activities	(28)	11
Financial Items	(11)	(13)
Earnings before income taxes	(39)	(2)
Tax expense (income)	(10)	0
Net loss	(29)	(2)
Royalty expense	0	0
Marketing and Other Contra Revenue Items	0	0
Purchases of crude oil and products(1)	1,349	2,175
Production, operating and transportation expenses(1) (note 21)	65	153
Selling, general and administrative expenses (note 21)	44	9
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	62	83
Expense arising from exploration for and evaluation of mineral resources	0	0
Gains (losses) on disposals of property, plant and equipment	0	(6)
Other – net(1) (notes 14, 25, 26)	(4)	0
Share of equity investment income (note 12)	0	0
Net foreign exchange gain	0	0
Finance income	0	0
Finance costs	11	13
Provisions for (recovery of) income taxes. current	0	0
Deferred tax expense (income)	(10)	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member]
Disclosure of operating segments [line items]
Revenue from sale of goods	(602)	(948)
Royalties	0	0
Marketing and Other Contra Revenue Items	0	0
Revenues, net of royalties	(602)	(948)
Purchases of crude oil and products(1)	(602)	(948)
Production, operating and transportation expenses(1) (note 21)	0	0
Selling, general and administrative expenses (note 21)	0	0
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	0	0
Expense arising from exploration for and evaluation of mineral resources	0	0
Gains (losses) on disposals of property, plant and equipment	0	0
Other – net(1) (notes 14, 25, 26)	0	0
Expenses	(602)	(948)
Earnings from operating activities	0	0
Share of equity investment income (note 12)	0	0
Net foreign exchange gain	0	0
Finance income	0	0
Finance expenses	0	0
Financial Items	0	0
Earnings before income taxes	0	0
Current tax expense (income) and adjustments for current tax of prior periods	0	0
Deferred tax expense (income)	0	0
Tax expense (income)	0	0
Net loss	0	0
Revenue from sale of goods	(602)	(948)
Revenue	(602)	(948)
Expenses	(602)	(948)
Earnings from operating activities	0	0
Financial Items	0	0
Earnings before income taxes	0	0
Tax expense (income)	0	0
Net loss	0	0
Royalty expense	0	0
Marketing and Other Contra Revenue Items	0	0
Purchases of crude oil and products(1)	(602)	(948)
Production, operating and transportation expenses(1) (note 21)	0	0
Selling, general and administrative expenses (note 21)	0	0
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	0	0
Expense arising from exploration for and evaluation of mineral resources	0	0
Gains (losses) on disposals of property, plant and equipment	0	0
Other – net(1) (notes 14, 25, 26)	0	0
Share of equity investment income (note 12)	0	0
Net foreign exchange gain	0	0
Finance income	0	0
Finance costs	0	0
Provisions for (recovery of) income taxes. current	0	0
Deferred tax expense (income)	0	0
Corporate
Disclosure of operating segments [line items]
Revenue from sale of goods	0	0
Royalties	0	0
Marketing and Other Contra Revenue Items	0	0
Revenues, net of royalties	0	0
Purchases of crude oil and products(1)	0	0
Production, operating and transportation expenses(1) (note 21)	0	0
Selling, general and administrative expenses (note 21)	262	290
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	92	104
Expense arising from exploration for and evaluation of mineral resources	0	0
Gains (losses) on disposals of property, plant and equipment	0	0
Other – net(1) (notes 14, 25, 26)	(157)	16
Expenses	197	378
Earnings from operating activities	(197)	(378)
Share of equity investment income (note 12)	0	0
Net foreign exchange gain	14	44
Finance income	18	71
Finance expenses	(206)	(151)
Financial Items	(174)	(36)
Earnings before income taxes	(371)	(414)
Current tax expense (income) and adjustments for current tax of prior periods	52	25
Deferred tax expense (income)	(21)	(329)
Tax expense (income)	31	(304)
Net loss	(402)	(110)
Revenue from sale of goods	0	0
Revenue	0	0
Expenses	197	378
Earnings from operating activities	(197)	(378)
Financial Items	(174)	(36)
Earnings before income taxes	(371)	(414)
Tax expense (income)	31	(304)
Net loss	(402)	(110)
Royalty expense	0	0
Marketing and Other Contra Revenue Items	0	0
Purchases of crude oil and products(1)	0	0
Production, operating and transportation expenses(1) (note 21)	0	0
Selling, general and administrative expenses (note 21)	262	290
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	92	104
Expense arising from exploration for and evaluation of mineral resources	0	0
Gains (losses) on disposals of property, plant and equipment	0	0
Other – net(1) (notes 14, 25, 26)	(157)	16
Share of equity investment income (note 12)	0	0
Net foreign exchange gain	14	44
Finance income	18	71
Finance costs	206	151
Provisions for (recovery of) income taxes. current	52	25
Deferred tax expense (income)	(21)	(329)
Operating Segments, Offshore [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods	1,515	1,553
Royalties	(87)	(109)
Marketing and Other Contra Revenue Items	0	0
Revenues, net of royalties	1,428	1,444
Purchases of crude oil and products(1)	32	(16)
Production, operating and transportation expenses(1) (note 21)	275	340
Selling, general and administrative expenses (note 21)	75	55
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	3,738	1,661
Expense arising from exploration for and evaluation of mineral resources	551	380
Gains (losses) on disposals of property, plant and equipment	1	1
Other – net(1) (notes 14, 25, 26)	(5)	1
Expenses	4,665	2,420
Earnings from operating activities	(3,237)	(976)
Share of equity investment income (note 12)	39	50
Net foreign exchange gain	0	0
Finance income	7	3
Finance expenses	(41)	(38)
Financial Items	(34)	(35)
Earnings before income taxes	(3,232)	(961)
Current tax expense (income) and adjustments for current tax of prior periods	150	125
Deferred tax expense (income)	(963)	(393)
Tax expense (income)	(813)	(268)
Net loss	(2,419)	(693)
Revenue from sale of goods	1,515	1,553
Revenue	1,428	1,444
Expenses	4,665	2,420
Earnings from operating activities	(3,237)	(976)
Financial Items	(34)	(35)
Earnings before income taxes	(3,232)	(961)
Tax expense (income)	(813)	(268)
Net loss	(2,419)	(693)
Royalty expense	87	109
Marketing and Other Contra Revenue Items	0	0
Purchases of crude oil and products(1)	32	(16)
Production, operating and transportation expenses(1) (note 21)	275	340
Selling, general and administrative expenses (note 21)	75	55
Depletion, depreciation, amortization and impairment (notes 9, 10, 11, 12)	3,738	1,661
Expense arising from exploration for and evaluation of mineral resources	551	380
Gains (losses) on disposals of property, plant and equipment	1	1
Other – net(1) (notes 14, 25, 26)	(5)	1
Share of equity investment income (note 12)	39	50
Net foreign exchange gain	0	0
Finance income	7	3
Finance costs	41	38
Provisions for (recovery of) income taxes. current	150	125
Deferred tax expense (income)	$ (963)	$ (393)

Description of Business and S_4

Description of Business and Segmented Disclosures - Segmented Financial Information (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Disclosure of disaggregation of revenue from contracts with customers [line items]
Expense arising from exploration for and evaluation of mineral resources	$ 1	$ 46
Expense Arising From Property, Plant and Equipment	1,586	3,386
Exploration and evaluation assets (note 8)	46	643
Total exploration and evaluation assets and property, plant and equipment, net	13,542	24,266
Right-of-use assets	698	1,202	$ 1,767
Total Assets	19,687	33,122
Total exploration and evaluation assets and property, plant and equipment, net	13,542	24,266
Expense arising from exploration for and evaluation of mineral resources	1	46
Expense Arising From Property, Plant and Equipment	1,586	3,386
Exploration and evaluation assets (note 8)	46	643
Right-of-use assets	698	1,202	$ 1,767
Assets	19,687	33,122
Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Expense arising from exploration for and evaluation of mineral resources	0	20
Expense Arising From Property, Plant and Equipment	1,154	2,009
Exploration and evaluation assets (note 8)	0	156
Total exploration and evaluation assets and property, plant and equipment, net	9,855	16,912
Right-of-use assets	423	772
Total Assets	13,444	22,261
Total exploration and evaluation assets and property, plant and equipment, net	9,855	16,912
Expense arising from exploration for and evaluation of mineral resources	0	20
Expense Arising From Property, Plant and Equipment	1,154	2,009
Exploration and evaluation assets (note 8)	0	156
Right-of-use assets	423	772
Assets	13,444	22,261
Operating Segments, Offshore [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Expense arising from exploration for and evaluation of mineral resources	1	26
Expense Arising From Property, Plant and Equipment	367	1,246
Exploration and evaluation assets (note 8)	46	487
Total exploration and evaluation assets and property, plant and equipment, net	3,382	7,005
Right-of-use assets	3	138
Total Assets	4,570	8,077
Total exploration and evaluation assets and property, plant and equipment, net	3,382	7,005
Expense arising from exploration for and evaluation of mineral resources	1	26
Expense Arising From Property, Plant and Equipment	367	1,246
Exploration and evaluation assets (note 8)	46	487
Right-of-use assets	3	138
Assets	4,570	8,077
Corporate
Disclosure of disaggregation of revenue from contracts with customers [line items]
Expense arising from exploration for and evaluation of mineral resources	0	0
Expense Arising From Property, Plant and Equipment	65	131
Exploration and evaluation assets (note 8)	0	0
Total exploration and evaluation assets and property, plant and equipment, net	305	349
Right-of-use assets	272	292
Total Assets	1,673	2,784
Total exploration and evaluation assets and property, plant and equipment, net	305	349
Expense arising from exploration for and evaluation of mineral resources	0	0
Expense Arising From Property, Plant and Equipment	65	131
Exploration and evaluation assets (note 8)	0	0
Right-of-use assets	272	292
Assets	1,673	2,784
Lloydminster Heavy Oil Value Chain [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Expense arising from exploration for and evaluation of mineral resources	0	17
Expense Arising From Property, Plant and Equipment	594	939
Exploration and evaluation assets (note 8)	0	154
Total exploration and evaluation assets and property, plant and equipment, net	5,238	6,672
Right-of-use assets	68	54
Total Assets	6,650	8,312
Total exploration and evaluation assets and property, plant and equipment, net	5,238	6,672
Expense arising from exploration for and evaluation of mineral resources	0	17
Expense Arising From Property, Plant and Equipment	594	939
Exploration and evaluation assets (note 8)	0	154
Right-of-use assets	68	54
Assets	6,650	8,312
Oil Sands [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Expense arising from exploration for and evaluation of mineral resources	0	0
Expense Arising From Property, Plant and Equipment	9	38
Exploration and evaluation assets (note 8)	0	0
Total exploration and evaluation assets and property, plant and equipment, net	590	2,087
Right-of-use assets	167	430
Total Assets	993	2,757
Total exploration and evaluation assets and property, plant and equipment, net	590	2,087
Expense arising from exploration for and evaluation of mineral resources	0	0
Expense Arising From Property, Plant and Equipment	9	38
Exploration and evaluation assets (note 8)	0	0
Right-of-use assets	167	430
Assets	993	2,757
Canadian Refined Products [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Expense arising from exploration for and evaluation of mineral resources	0	0
Expense Arising From Property, Plant and Equipment	5	73
Exploration and evaluation assets (note 8)	0	0
Total exploration and evaluation assets and property, plant and equipment, net	493	541
Right-of-use assets	102	122
Total Assets	625	838
Total exploration and evaluation assets and property, plant and equipment, net	493	541
Expense arising from exploration for and evaluation of mineral resources	0	0
Expense Arising From Property, Plant and Equipment	5	73
Exploration and evaluation assets (note 8)	0	0
Right-of-use assets	102	122
Assets	625	838
Western Canada Production [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Expense arising from exploration for and evaluation of mineral resources	0	3
Expense Arising From Property, Plant and Equipment	57	191
Exploration and evaluation assets (note 8)	0	2
Total exploration and evaluation assets and property, plant and equipment, net	667	1,560
Right-of-use assets	4	9
Total Assets	707	1,709
Total exploration and evaluation assets and property, plant and equipment, net	667	1,560
Expense arising from exploration for and evaluation of mineral resources	0	3
Expense Arising From Property, Plant and Equipment	57	191
Exploration and evaluation assets (note 8)	0	2
Right-of-use assets	4	9
Assets	707	1,709
U.S Refining [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Expense arising from exploration for and evaluation of mineral resources	0	0
Expense Arising From Property, Plant and Equipment	489	768
Exploration and evaluation assets (note 8)	0	0
Total exploration and evaluation assets and property, plant and equipment, net	2,867	6,052
Right-of-use assets	82	157
Total Assets	4,469	8,645
Total exploration and evaluation assets and property, plant and equipment, net	2,867	6,052
Expense arising from exploration for and evaluation of mineral resources	0	0
Expense Arising From Property, Plant and Equipment	489	768
Exploration and evaluation assets (note 8)	0	0
Right-of-use assets	82	157
Assets	4,469	8,645
Elimination of intersegment amounts [member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Expense arising from exploration for and evaluation of mineral resources	0	0
Expense Arising From Property, Plant and Equipment	0	0
Exploration and evaluation assets (note 8)	0	0
Total exploration and evaluation assets and property, plant and equipment, net	0	0
Right-of-use assets	0	0
Total Assets	0	0
Total exploration and evaluation assets and property, plant and equipment, net	0	0
Expense arising from exploration for and evaluation of mineral resources	0	0
Expense Arising From Property, Plant and Equipment	0	0
Exploration and evaluation assets (note 8)	0	0
Right-of-use assets	0	0
Assets	0	0
Cost
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	46,184	46,587
Other property, plant and equipment	17,059	16,093
Developing and producing assets	46,184	46,587
Other property, plant and equipment	17,059	16,093
Cost | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	31,082	31,857
Other property, plant and equipment	15,664	14,709
Developing and producing assets	31,082	31,857
Other property, plant and equipment	15,664	14,709
Cost | Operating Segments, Offshore [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	15,102	14,730
Other property, plant and equipment	7	7
Developing and producing assets	15,102	14,730
Other property, plant and equipment	7	7
Cost | Corporate
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	0	0
Other property, plant and equipment	1,388	1,377
Developing and producing assets	0	0
Other property, plant and equipment	1,388	1,377
Cost | Lloydminster Heavy Oil Value Chain [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	15,212	15,453
Other property, plant and equipment	4,189	3,820
Developing and producing assets	15,212	15,453
Other property, plant and equipment	4,189	3,820
Cost | Oil Sands [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	3,021	3,104
Other property, plant and equipment	76	3
Developing and producing assets	3,021	3,104
Other property, plant and equipment	76	3
Cost | Canadian Refined Products [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	0	0
Other property, plant and equipment	1,287	1,284
Developing and producing assets	0	0
Other property, plant and equipment	1,287	1,284
Cost | Western Canada Production [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	12,849	13,300
Other property, plant and equipment	55	62
Developing and producing assets	12,849	13,300
Other property, plant and equipment	55	62
Cost | U.S Refining [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	0	0
Other property, plant and equipment	10,057	9,540
Developing and producing assets	0	0
Other property, plant and equipment	10,057	9,540
Cost | Elimination of intersegment amounts [member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	0	0
Other property, plant and equipment	0	0
Developing and producing assets	0	0
Other property, plant and equipment	0	0
Accumulated depletion, depreciation, amortization and impairment
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	(37,889)	(31,348)
Other property, plant and equipment	(11,858)	(7,709)
Developing and producing assets	(37,889)	(31,348)
Other property, plant and equipment	(11,858)	(7,709)
Accumulated depletion, depreciation, amortization and impairment | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	(26,116)	(23,129)
Other property, plant and equipment	(10,775)	(6,681)
Developing and producing assets	(26,116)	(23,129)
Other property, plant and equipment	(10,775)	(6,681)
Accumulated depletion, depreciation, amortization and impairment | Operating Segments, Offshore [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	(11,773)	(8,219)
Other property, plant and equipment	0	0
Developing and producing assets	(11,773)	(8,219)
Other property, plant and equipment	0	0
Accumulated depletion, depreciation, amortization and impairment | Corporate
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	0	0
Other property, plant and equipment	(1,083)	(1,028)
Developing and producing assets	0	0
Other property, plant and equipment	(1,083)	(1,028)
Accumulated depletion, depreciation, amortization and impairment | Lloydminster Heavy Oil Value Chain [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	(11,411)	(10,345)
Other property, plant and equipment	(2,752)	(2,410)
Developing and producing assets	(11,411)	(10,345)
Other property, plant and equipment	(2,752)	(2,410)
Accumulated depletion, depreciation, amortization and impairment | Oil Sands [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	(2,498)	(1,020)
Other property, plant and equipment	(9)	0
Developing and producing assets	(2,498)	(1,020)
Other property, plant and equipment	(9)	0
Accumulated depletion, depreciation, amortization and impairment | Canadian Refined Products [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	0	0
Other property, plant and equipment	(794)	(743)
Developing and producing assets	0	0
Other property, plant and equipment	(794)	(743)
Accumulated depletion, depreciation, amortization and impairment | Western Canada Production [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	(12,207)	(11,764)
Other property, plant and equipment	(30)	(40)
Developing and producing assets	(12,207)	(11,764)
Other property, plant and equipment	(30)	(40)
Accumulated depletion, depreciation, amortization and impairment | U.S Refining [Member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	0	0
Other property, plant and equipment	(7,190)	(3,488)
Developing and producing assets	0	0
Other property, plant and equipment	(7,190)	(3,488)
Accumulated depletion, depreciation, amortization and impairment | Elimination of intersegment amounts [member] | Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Developing and producing assets	0	0
Other property, plant and equipment	0	0
Developing and producing assets	0	0
Other property, plant and equipment	$ 0	$ 0

Description of Business and S_5

Description of Business and Segmented Disclosures - Geographical (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	$ 13,463	$ 20,047
Royalties	(191)	(323)
Marketing and Other Contra Revenue Items	29	178
Revenues, net of royalties	13,301	19,902
Restricted cash – non-current	164	142
Exploration and evaluation assets (note 8)	46	643
Property, plant and equipment, net	13,496	23,623
Right-of-use assets	698	1,202	$ 1,767
Goodwill (note 11)	0	656		$ 690
Investment in joint ventures (note 12)	457	1,182
Long-term income taxes receivable	202	212
Net deferred tax assets	1,328	0
Other assets (note 14)	166	524
Non-current assets	16,557	28,184
Canada
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	5,648	8,734
Royalties	122	263
Marketing and Other Contra Revenue Items	11	(155)
Revenues, net of royalties	5,515	8,626
Restricted cash – non-current	0	0
Exploration and evaluation assets (note 8)	0	599
Property, plant and equipment, net	7,893	14,630
Right-of-use assets	616	1,044
Goodwill (note 11)	0	0
Investment in joint ventures (note 12)	0	666
Long-term income taxes receivable	202	212
Net deferred tax assets	1,127	0
Other assets (note 14)	30	47
Non-current assets	9,868	17,198
United States
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	6,636	10,253
Royalties	0	0
Marketing and Other Contra Revenue Items	(40)	(23)
Revenues, net of royalties	6,676	10,276
Restricted cash – non-current	0	0
Exploration and evaluation assets (note 8)	0	0
Property, plant and equipment, net	2,868	6,053
Right-of-use assets	81	156
Goodwill (note 11)	0	656
Investment in joint ventures (note 12)	0	0
Long-term income taxes receivable	0	0
Net deferred tax assets	187	0
Other assets (note 14)	119	458
Non-current assets	3,255	7,323
China
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,179	1,060
Royalties	(69)	(60)
Marketing and Other Contra Revenue Items	0	0
Revenues, net of royalties	1,110	1,000
Restricted cash – non-current	164	142
Exploration and evaluation assets (note 8)	41	39
Property, plant and equipment, net	2,735	2,938
Right-of-use assets	1	2
Goodwill (note 11)	0	0
Investment in joint ventures (note 12)	0	0
Long-term income taxes receivable	0	0
Net deferred tax assets	0	0
Other assets (note 14)	0	0
Non-current assets	2,941	3,121
Other International
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Royalties	0	0
Marketing and Other Contra Revenue Items	0	0
Revenues, net of royalties	0	0
Restricted cash – non-current	0	0
Exploration and evaluation assets (note 8)	5	5
Property, plant and equipment, net	0	2
Right-of-use assets	0	0
Goodwill (note 11)	0	0
Investment in joint ventures (note 12)	457	516
Long-term income taxes receivable	0	0
Net deferred tax assets	14	0
Other assets (note 14)	17	19
Non-current assets	$ 493	$ 542

Description of Business and S_6

Description of Business and Segmented Disclosures Disaggregation of Revenue (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	$ 13,463	$ 20,047
Canada
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	5,648	8,734
United States
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	6,636	10,253
China
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,179	1,060
Light and Medium Crude Oil [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	418	660
Natural Gas Liquids [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	253	350
Natural Gas [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,179	1,037
Gasoline [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	4,073	6,318
Diesel and distillates [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	3,245	5,056
Asphalt [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	560	745
Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	3,658	4,884
Synthetic Crude Oil
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	981	1,495
Upgraded and refined products
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	8,859	13,614
Diluted Bitumen
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	308	640
Blended crude oil
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,500	2,197
Other Product Revenue
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,548	2,497
Corporate
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Canada
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | United States
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | China
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Light and Medium Crude Oil [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Natural Gas Liquids [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Natural Gas [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Gasoline [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Diesel and distillates [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Asphalt [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Synthetic Crude Oil
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Upgraded and refined products
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Diluted Bitumen
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Blended crude oil
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Corporate | Other Product Revenue
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	11,948	18,494
Operating Segments, Integrated Corridor [Member] | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	3,753	5,601
Operating Segments, Integrated Corridor [Member] | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	306	649
Operating Segments, Integrated Corridor [Member] | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	367	514
Operating Segments, Integrated Corridor [Member] | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	6,636	10,253
Operating Segments, Integrated Corridor [Member] | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,488	2,425
Operating Segments, Integrated Corridor [Member] | Canada
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	5,312	8,241
Operating Segments, Integrated Corridor [Member] | Canada | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	3,753	5,601
Operating Segments, Integrated Corridor [Member] | Canada | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	306	649
Operating Segments, Integrated Corridor [Member] | Canada | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	367	514
Operating Segments, Integrated Corridor [Member] | Canada | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Canada | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,488	2,425
Operating Segments, Integrated Corridor [Member] | United States
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	6,636	10,253
Operating Segments, Integrated Corridor [Member] | United States | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | United States | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | United States | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | United States | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	6,636	10,253
Operating Segments, Integrated Corridor [Member] | United States | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | China
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | China | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | China | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | China | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | China | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | China | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Light and Medium Crude Oil [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	82	167
Operating Segments, Integrated Corridor [Member] | Light and Medium Crude Oil [Member] | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Light and Medium Crude Oil [Member] | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Light and Medium Crude Oil [Member] | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	82	167
Operating Segments, Integrated Corridor [Member] | Light and Medium Crude Oil [Member] | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Light and Medium Crude Oil [Member] | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Natural Gas Liquids [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	101	168
Operating Segments, Integrated Corridor [Member] | Natural Gas Liquids [Member] | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Natural Gas Liquids [Member] | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Natural Gas Liquids [Member] | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	101	168
Operating Segments, Integrated Corridor [Member] | Natural Gas Liquids [Member] | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Natural Gas Liquids [Member] | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Natural Gas [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	153	162
Operating Segments, Integrated Corridor [Member] | Natural Gas [Member] | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Natural Gas [Member] | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Natural Gas [Member] | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	153	162
Operating Segments, Integrated Corridor [Member] | Natural Gas [Member] | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Natural Gas [Member] | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Gasoline [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	4,073	6,318
Operating Segments, Integrated Corridor [Member] | Gasoline [Member] | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Gasoline [Member] | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Gasoline [Member] | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Gasoline [Member] | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	3,453	5,414
Operating Segments, Integrated Corridor [Member] | Gasoline [Member] | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	620	904
Operating Segments, Integrated Corridor [Member] | Diesel and distillates [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	3,245	5,056
Operating Segments, Integrated Corridor [Member] | Diesel and distillates [Member] | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	170	260
Operating Segments, Integrated Corridor [Member] | Diesel and distillates [Member] | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Diesel and distillates [Member] | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Diesel and distillates [Member] | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	2,282	3,644
Operating Segments, Integrated Corridor [Member] | Diesel and distillates [Member] | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	793	1,152
Operating Segments, Integrated Corridor [Member] | Asphalt [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	560	745
Operating Segments, Integrated Corridor [Member] | Asphalt [Member] | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	475	609
Operating Segments, Integrated Corridor [Member] | Asphalt [Member] | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Asphalt [Member] | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Asphalt [Member] | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	85	136
Operating Segments, Integrated Corridor [Member] | Asphalt [Member] | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	2,144	3,334
Operating Segments, Integrated Corridor [Member] | Refined Products [Member] | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,500	2,197
Operating Segments, Integrated Corridor [Member] | Refined Products [Member] | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	308	640
Operating Segments, Integrated Corridor [Member] | Refined Products [Member] | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	336	497
Operating Segments, Integrated Corridor [Member] | Refined Products [Member] | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Refined Products [Member] | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Synthetic Crude Oil
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	981	1,495
Operating Segments, Integrated Corridor [Member] | Synthetic Crude Oil | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	981	1,495
Operating Segments, Integrated Corridor [Member] | Synthetic Crude Oil | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Synthetic Crude Oil | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Synthetic Crude Oil | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Synthetic Crude Oil | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Upgraded and refined products
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	8,859	13,614
Operating Segments, Integrated Corridor [Member] | Upgraded and refined products | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,626	2,364
Operating Segments, Integrated Corridor [Member] | Upgraded and refined products | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Upgraded and refined products | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Upgraded and refined products | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	5,820	9,194
Operating Segments, Integrated Corridor [Member] | Upgraded and refined products | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,413	2,056
Operating Segments, Integrated Corridor [Member] | Diluted Bitumen
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	308	640
Operating Segments, Integrated Corridor [Member] | Diluted Bitumen | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Diluted Bitumen | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	308	640
Operating Segments, Integrated Corridor [Member] | Diluted Bitumen | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Diluted Bitumen | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Diluted Bitumen | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Blended crude oil
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,500	2,197
Operating Segments, Integrated Corridor [Member] | Blended crude oil | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,500	2,197
Operating Segments, Integrated Corridor [Member] | Blended crude oil | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Blended crude oil | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Blended crude oil | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Blended crude oil | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Other Product Revenue
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,547	2,494
Operating Segments, Integrated Corridor [Member] | Other Product Revenue | Lloydminster Heavy Oil Value Chain [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	627	1,040
Operating Segments, Integrated Corridor [Member] | Other Product Revenue | Oil Sands [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	(2)	9
Operating Segments, Integrated Corridor [Member] | Other Product Revenue | Western Canada Production [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	31	17
Operating Segments, Integrated Corridor [Member] | Other Product Revenue | U.S Refining [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	816	1,059
Operating Segments, Integrated Corridor [Member] | Other Product Revenue | Canadian Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	75	369
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	(602)	(948)
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Canada
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	(602)	(948)
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | United States
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | China
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Light and Medium Crude Oil [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Natural Gas Liquids [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Natural Gas [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Gasoline [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Diesel and distillates [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Asphalt [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Synthetic Crude Oil
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Upgraded and refined products
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Diluted Bitumen
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Blended crude oil
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Integrated Corridor [Member] | Elimination of intersegment amounts [member] | Other Product Revenue
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Offshore [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,515	1,553
Operating Segments, Offshore [Member] | Canada
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	336	493
Operating Segments, Offshore [Member] | United States
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Offshore [Member] | China
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,179	1,060
Operating Segments, Offshore [Member] | Light and Medium Crude Oil [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	336	493
Operating Segments, Offshore [Member] | Natural Gas Liquids [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	152	182
Operating Segments, Offshore [Member] | Natural Gas [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,026	875
Operating Segments, Offshore [Member] | Gasoline [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Offshore [Member] | Diesel and distillates [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Offshore [Member] | Asphalt [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Offshore [Member] | Refined Products [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	1,514	1,550
Operating Segments, Offshore [Member] | Synthetic Crude Oil
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Offshore [Member] | Upgraded and refined products
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Offshore [Member] | Diluted Bitumen
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Offshore [Member] | Blended crude oil
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	0	0
Operating Segments, Offshore [Member] | Other Product Revenue
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenue from sale of goods	$ 1	$ 3

Cash and Cash Equivalents (Deta

Cash and Cash Equivalents (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Subclassifications of assets, liabilities and equities [abstract]
Cash	$ 709	$ 327
Short-term investments, classified as cash equivalents	$ 26	$ 1,448

Accounts Receivable (Details)

Accounts Receivable (Details) - Within 1 year - CAD ($)	Dec. 31, 2020	Dec. 31, 2019
Subclassifications of assets, liabilities and equities [abstract]
Receivables and payables related to insurance contracts	$ 312	$ 114,000,000
Receivables by term classification [Table]
Receivables and payables related to insurance contracts	$ 312	$ 114,000,000

Inventories (Details)

Inventories (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Subclassifications of assets, liabilities and equities [abstract]
Refined petroleum products	$ 411	$ 553
Trading inventories measured at fair value less costs to sell	121	155
Materials, supplies and other	174	151
Inventories	1,115	1,486
Inventory write-down to net realizable value (note 6)	7	15
Crude oil, natural gas and NGL	$ 409	$ 627

Restricted Cash Restricted Cash

Restricted Cash Restricted Cash (Details) - Peoples Republic of China - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Disclosure of geographical areas [line items]
Restricted cash and cash equivalents	$ 164	$ 142
Restricted cash and cash equivalents	$ 164	$ 142

Exploration and Evaluation Co_3

Exploration and Evaluation Costs - Exploration and Evaluation Assets (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, beginning balance	$ 23,623,000,000
Expensed exploration expenditures previously capitalized	594,000,000	$ 355,000,000
Property, plant and equipment, ending balance	13,496,000,000	23,623,000,000
Write-down of Exploration		331
Operating Segments, Offshore [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Write-down of Exploration	439
Lloydminster Heavy Oil Value Chain [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Write-down of Exploration	150
Tangible exploration and evaluation assets
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, beginning balance	643,000,000	997,000,000
Transfers to right-of-use assets(1) (note 10)	1,000,000	46,000,000
Transfers to property, plant and equipment (note 9)	(3,000,000)	(44,000,000)
Expensed exploration expenditures previously capitalized	(594,000,000)	(355,000,000)
Exchange adjustments	(1,000,000)	(1,000,000)
Property, plant and equipment, ending balance	$ 46,000,000	$ 643,000,000

Exploration and Evaluation Co_4

Exploration and Evaluation Costs - Exploration and Evaluation Expense Summary (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Subclassifications of assets, liabilities and equities [abstract]
Seismic, geological and geophysical	$ 117	$ 131
Expensed drilling	612	409
Expensed land	4	7
Exploration and evaluation expenses	$ 733	$ 547

Property, Plant and Equipment -

Property, Plant and Equipment - Property, Plant and Equipment (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	$ 23,623,000,000
Property, plant and equipment, ending balance	13,496,000,000	$ 23,623,000,000
Impairment loss (reversal of impairment loss) recognised in profit or loss	$ 11,220	$ 2,584
Discount rate used in current measurement of fair value less costs of disposal	1200.00%	1000.00%
Oil and Gas Properties
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	$ 15,239,000,000
Property, plant and equipment, ending balance	8,423,000,000	$ 15,239,000,000
Processing, Transportation and Storage
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	50,000,000
Property, plant and equipment, ending balance	53,000,000	50,000,000
Upgrading [Member]
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	1,021,000,000
Property, plant and equipment, ending balance	1,134,000,000	1,021,000,000
Refining
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	6,282,000,000
Property, plant and equipment, ending balance	3,097,000,000	6,282,000,000
Retail and Other
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	1,031,000,000
Property, plant and equipment, ending balance	789,000,000	1,031,000,000
Cost
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	62,671,000,000	60,742,000,000
Transfers to right-of-use assets(1) (note 10)	1,640,000,000	3,459,000,000
Additions	1,000,000	10,000,000
Acquisitions	3,000,000	44,000,000
ifrs-full_EffectiveDateOfRevaluationRightofuseAssets	4,000,000	101,000,000
Intersegment transfers	0	0
Transfers from right-of-use assets(2) (note 10)	(627,000,000)	517,000,000
Intersegment transfers	(435,000,000)	(964,000,000)
Exchange adjustments	(20,000,000)	(722,000,000)
Property, plant and equipment, ending balance	63,237,000,000	62,671,000,000
Transfers to right-of-use assets		(516,000,000)
Transfers to right-of-use assets(1) (note 10)	1,640,000,000	3,459,000,000
Additions	1,000,000	10,000,000
Transfers to property, plant and equipment (note 9)	3,000,000	44,000,000
Intersegment transfers	0	0
Transfers from right-of-use assets(2) (note 10)	(627,000,000)	517,000,000
Disposals and retirements, property, plant and equipment	435,000,000	964,000,000
Cost | Oil and Gas Properties
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	46,587,000,000	44,196,000,000
Transfers to right-of-use assets(1) (note 10)	852,000,000	2,340,000,000
Additions	1,000,000	10,000,000
Acquisitions	3,000,000	44,000,000
ifrs-full_EffectiveDateOfRevaluationRightofuseAssets	4,000,000	101,000,000
Intersegment transfers	18,000,000	2,000,000
Transfers from right-of-use assets(2) (note 10)	(530,000,000)	469,000,000
Intersegment transfers	(419,000,000)	(16,000,000)
Exchange adjustments	(80,000,000)	(223,000,000)
Property, plant and equipment, ending balance	46,436,000,000	46,587,000,000
Transfers to right-of-use assets		(336,000,000)
Transfers to right-of-use assets(1) (note 10)	852,000,000	2,340,000,000
Additions	1,000,000	10,000,000
Transfers to property, plant and equipment (note 9)	3,000,000	44,000,000
Intersegment transfers	18,000,000	2,000,000
Transfers from right-of-use assets(2) (note 10)	(530,000,000)	469,000,000
Disposals and retirements, property, plant and equipment	419,000,000	16,000,000
Cost | Processing, Transportation and Storage
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	101,000,000	101,000,000
Transfers to right-of-use assets(1) (note 10)	0	2,000,000
Additions	0	0
Acquisitions	0	0
ifrs-full_EffectiveDateOfRevaluationRightofuseAssets	0	0
Intersegment transfers	41,000,000	0
Transfers from right-of-use assets(2) (note 10)	0	1,000,000
Intersegment transfers	(2,000,000)	(2,000,000)
Exchange adjustments	(3,000,000)	(1,000,000)
Property, plant and equipment, ending balance	137,000,000	101,000,000
Transfers to right-of-use assets		0
Transfers to right-of-use assets(1) (note 10)	0	2,000,000
Additions	0	0
Transfers to property, plant and equipment (note 9)	0	0
Intersegment transfers	41,000,000	0
Transfers from right-of-use assets(2) (note 10)	0	1,000,000
Disposals and retirements, property, plant and equipment	2,000,000	2,000,000
Cost | Upgrading [Member]
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	2,721,000,000	2,659,000,000
Transfers to right-of-use assets(1) (note 10)	216,000,000	58,000,000
Additions	0	0
Acquisitions	0	0
ifrs-full_EffectiveDateOfRevaluationRightofuseAssets	0	0
Intersegment transfers	0	0
Transfers from right-of-use assets(2) (note 10)	(13,000,000)	5,000,000
Intersegment transfers	0	(1,000,000)
Exchange adjustments	0	0
Property, plant and equipment, ending balance	2,924,000,000	2,721,000,000
Transfers to right-of-use assets		0
Transfers to right-of-use assets(1) (note 10)	216,000,000	58,000,000
Additions	0	0
Transfers to property, plant and equipment (note 9)	0	0
Intersegment transfers	0	0
Transfers from right-of-use assets(2) (note 10)	(13,000,000)	5,000,000
Disposals and retirements, property, plant and equipment	0	1,000,000
Cost | Refining
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	10,017,000,000	10,691,000,000
Transfers to right-of-use assets(1) (note 10)	502,000,000	899,000,000
Additions	0	0
Acquisitions	0	0
ifrs-full_EffectiveDateOfRevaluationRightofuseAssets	0	0
Intersegment transfers	0	27,000,000
Transfers from right-of-use assets(2) (note 10)	(51,000,000)	19,000,000
Intersegment transfers	(12,000,000)	(943,000,000)
Exchange adjustments	64,000,000	(496,000,000)
Property, plant and equipment, ending balance	10,520,000,000	10,017,000,000
Transfers to right-of-use assets		(180,000,000)
Transfers to right-of-use assets(1) (note 10)	502,000,000	899,000,000
Additions	0	0
Transfers to property, plant and equipment (note 9)	0	0
Intersegment transfers	0	27,000,000
Transfers from right-of-use assets(2) (note 10)	(51,000,000)	19,000,000
Disposals and retirements, property, plant and equipment	12,000,000	943,000,000
Cost | Retail and Other
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	3,245,000,000	3,095,000,000
Transfers to right-of-use assets(1) (note 10)	70,000,000	160,000,000
Additions	0	0
Acquisitions	0	0
ifrs-full_EffectiveDateOfRevaluationRightofuseAssets	0	0
Intersegment transfers	(59,000,000)	(29,000,000)
Transfers from right-of-use assets(2) (note 10)	(33,000,000)	23,000,000
Intersegment transfers	(2,000,000)	(2,000,000)
Exchange adjustments	(1,000,000)	(2,000,000)
Property, plant and equipment, ending balance	3,220,000,000	3,245,000,000
Transfers to right-of-use assets		0
Transfers to right-of-use assets(1) (note 10)	70,000,000	160,000,000
Additions	0	0
Transfers to property, plant and equipment (note 9)	0	0
Intersegment transfers	(59,000,000)	(29,000,000)
Transfers from right-of-use assets(2) (note 10)	(33,000,000)	23,000,000
Disposals and retirements, property, plant and equipment	2,000,000	2,000,000
Accumulated depletion, depreciation, amortization and impairment
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	(39,048,000,000)	(34,942,000,000)
Intersegment transfers	0	0
Intersegment transfers	393,000,000	734,000,000
Exchange adjustments	5,000,000	282,000,000
Transfers to right-of-use assets(1) (note 10)	(11,091,000,000)	(5,174,000,000)
Property, plant and equipment, ending balance	(49,741,000,000)	(39,048,000,000)
Transfers to right-of-use assets		(52,000,000)
Intersegment transfers	0	0
Disposals and retirements, property, plant and equipment	(393,000,000)	(734,000,000)
Depletion, Depreciation, Amortization and Impairment, Plant and Equipment	11,091,000,000	5,174,000,000
Accumulated depletion, depreciation, amortization and impairment | Oil and Gas Properties
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	(31,348,000,000)	(27,379,000,000)
Intersegment transfers	9,000,000	0
Intersegment transfers	380,000,000	8,000,000
Exchange adjustments	47,000,000	93,000,000
Transfers to right-of-use assets(1) (note 10)	(7,083,000,000)	(4,082,000,000)
Property, plant and equipment, ending balance	(38,013,000,000)	(31,348,000,000)
Transfers to right-of-use assets		(12,000,000)
Intersegment transfers	9,000,000	0
Disposals and retirements, property, plant and equipment	(380,000,000)	(8,000,000)
Depletion, Depreciation, Amortization and Impairment, Plant and Equipment	7,083,000,000	4,082,000,000
Accumulated depletion, depreciation, amortization and impairment | Processing, Transportation and Storage
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	(51,000,000)	(50,000,000)
Intersegment transfers	0	0
Intersegment transfers	12,000,000	0
Exchange adjustments	1,000,000	1,000,000
Transfers to right-of-use assets(1) (note 10)	(46,000,000)	(2,000,000)
Property, plant and equipment, ending balance	(84,000,000)	(51,000,000)
Transfers to right-of-use assets		0
Intersegment transfers	0	0
Disposals and retirements, property, plant and equipment	(12,000,000)	0
Depletion, Depreciation, Amortization and Impairment, Plant and Equipment	46,000,000	2,000,000
Accumulated depletion, depreciation, amortization and impairment | Upgrading [Member]
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	(1,700,000,000)	(1,585,000,000)
Intersegment transfers	0	0
Intersegment transfers	0	0
Exchange adjustments	0	0
Transfers to right-of-use assets(1) (note 10)	(90,000,000)	(115,000,000)
Property, plant and equipment, ending balance	(1,790,000,000)	(1,700,000,000)
Transfers to right-of-use assets		0
Intersegment transfers	0	0
Disposals and retirements, property, plant and equipment	0	0
Depletion, Depreciation, Amortization and Impairment, Plant and Equipment	90,000,000	115,000,000
Accumulated depletion, depreciation, amortization and impairment | Refining
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	(3,735,000,000)	(3,933,000,000)
Intersegment transfers	0	17,000,000
Intersegment transfers	0	724,000,000
Exchange adjustments	(44,000,000)	187,000,000
Transfers to right-of-use assets(1) (note 10)	(3,644,000,000)	(736,000,000)
Property, plant and equipment, ending balance	(7,423,000,000)	(3,735,000,000)
Transfers to right-of-use assets		(40,000,000)
Intersegment transfers	0	17,000,000
Disposals and retirements, property, plant and equipment	0	(724,000,000)
Depletion, Depreciation, Amortization and Impairment, Plant and Equipment	3,644,000,000	736,000,000
Accumulated depletion, depreciation, amortization and impairment | Retail and Other
Reconciliation of changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	(2,214,000,000)	(1,995,000,000)
Intersegment transfers	(9,000,000)	(17,000,000)
Intersegment transfers	1,000,000	2,000,000
Exchange adjustments	1,000,000	1,000,000
Transfers to right-of-use assets(1) (note 10)	(228,000,000)	(239,000,000)
Property, plant and equipment, ending balance	(2,431,000,000)	(2,214,000,000)
Transfers to right-of-use assets		0
Intersegment transfers	(9,000,000)	(17,000,000)
Disposals and retirements, property, plant and equipment	(1,000,000)	(2,000,000)
Depletion, Depreciation, Amortization and Impairment, Plant and Equipment	$ 228,000,000	$ 239,000,000

Property, Plant and Equipment_2

Property, Plant and Equipment (Details)	12 Months Ended
	Dec. 31, 2020CAD ($)	Dec. 31, 2019CAD ($)	Dec. 31, 2020USD ($)
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	$ 11,220	$ 2,584
Recoverable amount of asset or cash-generating unit	6,204
Increase (Decrease) In Impairment of Property, Plant, And Equipment Attributable To 1% Increase In Discount Rate	599,000,000
Increase (Decrease) In Impairment of Property, Plant, And Equipment Attributable To 1% Decrease In Discount Rate	(687,000,000)
Increase (Decrease) In Impairment of Property, Plant, And Equipment Attributable To 5% Increase In Forward Price	(1,511,000,000)
Increase (Decrease) In Impairment of Property, Plant, And Equipment Attributable To 5% Decrease In Forward Price	1,530,000,000
Income from reimbursements under insurance policies	85,000,000	630
PPE, not subject to depletion, depreciation and amortization	2,000,000,000	$ 6,800,000,000
Cash Generating Unit, Forecasted Price increase after Year 5	$ 2
Discount rate used in current measurement of fair value less costs of disposal	1200.00%	1000.00%	1200.00%
Operating Segments, Integrated Corridor [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	$ 7,527,000,000
Operating Segments, Offshore [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	3,104,000,000
White Rose CGU
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	2,854,000,000
Terra Nova CGU
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	250,000,000
Western Texas Intermediate
Property, plant and equipment [abstract]
Cash Generating Unit, Forecasted Price, Year 1			$ 47.17
Cash Generating Unit, Forecasted Price, Year 2			50.17
Cash Generating Unit, Forecasted Price, Year 3			53.17
Cash Generating Unit, Forecasted Price, Year 4			54.97
Cash Generating Unit, Forecasted Price, Year 5			56.07
Brent Crude
Property, plant and equipment [abstract]
Cash Generating Unit, Forecasted Price, Year 1			49.42
Cash Generating Unit, Forecasted Price, Year 2			52.85
Cash Generating Unit, Forecasted Price, Year 3			56.04
Cash Generating Unit, Forecasted Price, Year 4			57.87
Cash Generating Unit, Forecasted Price, Year 5			59
Edmonton Light
Property, plant and equipment [abstract]
Cash Generating Unit, Forecasted Price, Year 1	55.76
Cash Generating Unit, Forecasted Price, Year 2	59.89
Cash Generating Unit, Forecasted Price, Year 3	63.48
Cash Generating Unit, Forecasted Price, Year 4	65.76
Cash Generating Unit, Forecasted Price, Year 5	67.13
Alberta Energy Company
Property, plant and equipment [abstract]
Cash Generating Unit, Forecasted Price, Year 1	2.78
Cash Generating Unit, Forecasted Price, Year 2	2.70
Cash Generating Unit, Forecasted Price, Year 3	2.61
Cash Generating Unit, Forecasted Price, Year 4	2.65
Cash Generating Unit, Forecasted Price, Year 5	2.70
Chicago 3-2-1 Crack Spread
Property, plant and equipment [abstract]
Cash Generating Unit, Forecasted Price, Year 1			12
Cash Generating Unit, Forecasted Price, Year 2			14
Cash Generating Unit, Forecasted Price, Year 3			14
Cash Generating Unit, Forecasted Price, Year 4			16
Cash Generating Unit, Forecasted Price, Year 5			16
$USD/$CAD Foreign exchange rate
Property, plant and equipment [abstract]
Cash Generating Unit, Forecasted Price, Year 1			0.77
Cash Generating Unit, Forecasted Price, Year 2			0.77
Cash Generating Unit, Forecasted Price, Year 3			0.76
Cash Generating Unit, Forecasted Price, Year 4			0.76
Cash Generating Unit, Forecasted Price, Year 5			$ 0.76
Property, plant and equipment [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	8,945
Property, plant and equipment [member] | Operating Segments, Integrated Corridor [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	5,935,000,000
Property, plant and equipment [member] | Operating Segments, Offshore [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	3,010,000,000
Property, plant and equipment [member] | White Rose CGU
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	2,760,000,000
Property, plant and equipment [member] | Terra Nova CGU
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	250,000,000
Right-of-use assets [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	411	$ 165
Right-of-use assets [member] | Operating Segments, Integrated Corridor [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	317,000,000
Right-of-use assets [member] | Operating Segments, Offshore [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	94,000,000
Right-of-use assets [member] | White Rose CGU
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	94,000,000
Right-of-use assets [member] | Terra Nova CGU
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Goodwill
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	669,000,000	$ 0
Recoverable amount of asset or cash-generating unit	$ 0
Discount rate used in current measurement of fair value less costs of disposal	1200.00%	900.00%	1200.00%
Goodwill | Operating Segments, Integrated Corridor [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	$ 669,000,000
Joint ventures [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	606
Recoverable amount of asset or cash-generating unit	$ 0
Discount rate used in current measurement of fair value less costs of disposal	1200.00%		1200.00%
Joint ventures [member] | Operating Segments, Integrated Corridor [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	$ 606,000,000
Lloydminster Heavy Oil Value Chain [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	1,250,000,000
Lloydminster Heavy Oil Value Chain [Member] | Lloydminster heavy oil & gas
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	271,000,000
Lloydminster Heavy Oil Value Chain [Member] | Tucker
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	271,000,000
Lloydminster Heavy Oil Value Chain [Member] | Minnedosa Ethanol Plant
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	42,000,000
Lloydminster Heavy Oil Value Chain [Member] | Lloydminster Ethanol Plant
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	60,000,000
Lloydminster Heavy Oil Value Chain [Member] | Husky Midstream Limited Partnership
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	606,000,000
Lloydminster Heavy Oil Value Chain [Member] | Property, plant and equipment [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	640,000,000
Lloydminster Heavy Oil Value Chain [Member] | Property, plant and equipment [member] | Lloydminster heavy oil & gas
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	270,000,000
Lloydminster Heavy Oil Value Chain [Member] | Property, plant and equipment [member] | Tucker
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	271,000,000
Lloydminster Heavy Oil Value Chain [Member] | Property, plant and equipment [member] | Minnedosa Ethanol Plant
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	42,000,000
Lloydminster Heavy Oil Value Chain [Member] | Property, plant and equipment [member] | Lloydminster Ethanol Plant
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	57,000,000
Lloydminster Heavy Oil Value Chain [Member] | Property, plant and equipment [member] | Husky Midstream Limited Partnership
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Right-of-use assets [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	4,000,000
Lloydminster Heavy Oil Value Chain [Member] | Right-of-use assets [member] | Lloydminster heavy oil & gas
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	1,000,000
Lloydminster Heavy Oil Value Chain [Member] | Right-of-use assets [member] | Tucker
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Right-of-use assets [member] | Minnedosa Ethanol Plant
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Right-of-use assets [member] | Lloydminster Ethanol Plant
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	3,000,000
Lloydminster Heavy Oil Value Chain [Member] | Right-of-use assets [member] | Husky Midstream Limited Partnership
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Goodwill
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Goodwill | Lloydminster heavy oil & gas
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Goodwill | Tucker
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Goodwill | Minnedosa Ethanol Plant
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Goodwill | Lloydminster Ethanol Plant
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Goodwill | Husky Midstream Limited Partnership
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Joint ventures [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	606,000,000
Lloydminster Heavy Oil Value Chain [Member] | Joint ventures [member] | Lloydminster heavy oil & gas
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Joint ventures [member] | Tucker
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Joint ventures [member] | Minnedosa Ethanol Plant
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Joint ventures [member] | Lloydminster Ethanol Plant
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Lloydminster Heavy Oil Value Chain [Member] | Joint ventures [member] | Husky Midstream Limited Partnership
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	606,000,000
Western Canada Production [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	638,000,000
Western Canada Production [Member] | Northern Western Canada
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	519,000,000
Western Canada Production [Member] | Rainbow lake
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	119,000,000
Western Canada Production [Member] | Property, plant and equipment [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	636,000,000
Western Canada Production [Member] | Property, plant and equipment [member] | Northern Western Canada
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	517,000,000
Western Canada Production [Member] | Property, plant and equipment [member] | Rainbow lake
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	119,000,000
Western Canada Production [Member] | Right-of-use assets [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	2,000,000
Western Canada Production [Member] | Right-of-use assets [member] | Northern Western Canada
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	2,000,000
Western Canada Production [Member] | Right-of-use assets [member] | Rainbow lake
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Western Canada Production [Member] | Goodwill
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Western Canada Production [Member] | Goodwill | Northern Western Canada
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Western Canada Production [Member] | Goodwill | Rainbow lake
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Western Canada Production [Member] | Joint ventures [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Western Canada Production [Member] | Joint ventures [member] | Northern Western Canada
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Western Canada Production [Member] | Joint ventures [member] | Rainbow lake
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
U.S Refining [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	3,956,000,000
U.S Refining [Member] | Lima Refinery CGU
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	1,922,000,000
U.S Refining [Member] | BP- HUSKY Toledo Refinery
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	1,668,000,000
U.S Refining [Member] | Superior Refinery [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	366,000,000
U.S Refining [Member] | Property, plant and equipment [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	3,231,000,000
U.S Refining [Member] | Property, plant and equipment [member] | Lima Refinery CGU
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	1,203,000,000
U.S Refining [Member] | Property, plant and equipment [member] | BP- HUSKY Toledo Refinery
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	1,662,000,000
U.S Refining [Member] | Property, plant and equipment [member] | Superior Refinery [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	366,000,000
U.S Refining [Member] | Right-of-use assets [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	56,000,000
U.S Refining [Member] | Right-of-use assets [member] | Lima Refinery CGU
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	50,000,000
U.S Refining [Member] | Right-of-use assets [member] | BP- HUSKY Toledo Refinery
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	6,000,000
U.S Refining [Member] | Right-of-use assets [member] | Superior Refinery [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
U.S Refining [Member] | Goodwill
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	669,000,000
U.S Refining [Member] | Goodwill | Lima Refinery CGU
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	669,000,000
U.S Refining [Member] | Goodwill | BP- HUSKY Toledo Refinery
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
U.S Refining [Member] | Goodwill | Superior Refinery [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
U.S Refining [Member] | Joint ventures [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
U.S Refining [Member] | Joint ventures [member] | Lima Refinery CGU
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
U.S Refining [Member] | Joint ventures [member] | BP- HUSKY Toledo Refinery
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
U.S Refining [Member] | Joint ventures [member] | Superior Refinery [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Oil Sands [Member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	1,683,000,000
Oil Sands [Member] | Property, plant and equipment [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	1,428,000,000
Oil Sands [Member] | Right-of-use assets [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	255,000,000
Oil Sands [Member] | Goodwill
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	0
Oil Sands [Member] | Joint ventures [member]
Property, plant and equipment [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	$ 0

Leases (Details)

Leases (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Disclosure of quantitative information about leases for lessee [abstract]
Right-of-use assets	$ 698,000,000	$ 1,202,000,000	$ 1,767,000,000
Additions to right-of-use assets	30,000,000	86,000,000
Right-Of-Use Assets, Transfers To Property, Plant, And Equipment	(4,000,000)	(101,000,000)
Right-Of-Use Assets, Disposals And Derecognition	(3,000,000)	(40,000,000)
Right-of-use assets, revaluation surplus	27,000,000	(186,000,000)
Depreciation, right-of-use assets	(554,000,000)	(322,000,000)
Right-Of-Use Assets, Other Increase (Decrease)	0	(2,000,000)
Impairment loss (reversal of impairment loss) recognised in profit or loss	11,220	2,584
Right-Of-Use Assets, Transfers From Property, Plant, And Equipment			464,000,000
Current lease liabilities	102,000,000	109,000,000
Non-current lease liabilities	1,298,000,000	1,353,000,000
Lease liabilities future payments	2,869,000,000	3,032,000,000
Lease Liabilities, Interest	1,469,000,000	1,570,000,000
Lease liabilities	1,400,000,000	1,462,000,000
Interest expense on lease liabilities	97,000,000	106,000,000
Expense relating to short-term leases for which recognition exemption has been used	13,000,000	18,000,000
Payments of finance lease liabilities, classified as financing activities	208,000,000	339,000,000
Discounted Potential Lease Payments, Excluded From Lease Liabilities	250
At cost or in accordance with IFRS 16 within fair value model [member]
Disclosure of quantitative information about leases for lessee [abstract]
Right-of-use assets			1,303,000,000
Oil and Gas Properties
Disclosure of quantitative information about leases for lessee [abstract]
Right-of-use assets	120,000,000	520,000,000	1,045,000,000
Additions to right-of-use assets	5,000,000	1,000,000
Right-Of-Use Assets, Transfers To Property, Plant, And Equipment	(4,000,000)	(101,000,000)
Right-Of-Use Assets, Disposals And Derecognition	(3,000,000)	(11,000,000)
Right-of-use assets, revaluation surplus	0	(194,000,000)
Depreciation, right-of-use assets	(399,000,000)	(222,000,000)
Right-Of-Use Assets, Other Increase (Decrease)	1,000,000	2,000,000
Right-Of-Use Assets, Transfers From Property, Plant, And Equipment			324,000,000
Oil and Gas Properties | At cost or in accordance with IFRS 16 within fair value model [member]
Disclosure of quantitative information about leases for lessee [abstract]
Right-of-use assets			721,000,000
Processing, Transportation and Storage
Disclosure of quantitative information about leases for lessee [abstract]
Right-of-use assets	100,000,000	90,000,000	100,000,000
Additions to right-of-use assets	6,000,000	0
Right-Of-Use Assets, Transfers To Property, Plant, And Equipment	0	0
Right-Of-Use Assets, Disposals And Derecognition	0	0
Right-of-use assets, revaluation surplus	16,000,000	1,000,000
Depreciation, right-of-use assets	(11,000,000)	(11,000,000)
Right-Of-Use Assets, Other Increase (Decrease)	(1,000,000)	0
Right-Of-Use Assets, Transfers From Property, Plant, And Equipment			0
Processing, Transportation and Storage | At cost or in accordance with IFRS 16 within fair value model [member]
Disclosure of quantitative information about leases for lessee [abstract]
Right-of-use assets			100,000,000
Upgrading [Member]
Disclosure of quantitative information about leases for lessee [abstract]
Right-of-use assets	0	0	0
Additions to right-of-use assets	0	0
Right-Of-Use Assets, Transfers To Property, Plant, And Equipment	0	0
Right-Of-Use Assets, Disposals And Derecognition	0	0
Right-of-use assets, revaluation surplus	0	0
Depreciation, right-of-use assets	0	0
Right-Of-Use Assets, Other Increase (Decrease)	0	0
Right-Of-Use Assets, Transfers From Property, Plant, And Equipment			0
Upgrading [Member] | At cost or in accordance with IFRS 16 within fair value model [member]
Disclosure of quantitative information about leases for lessee [abstract]
Right-of-use assets			0
Office Building [Member]
Disclosure of quantitative information about leases for lessee [abstract]
Lease liabilities	361
Refining
Disclosure of quantitative information about leases for lessee [abstract]
Right-of-use assets	139,000,000	204,000,000	210,000,000
Additions to right-of-use assets	15,000,000	80,000,000
Right-Of-Use Assets, Transfers To Property, Plant, And Equipment	0	0
Right-Of-Use Assets, Disposals And Derecognition	0	(31,000,000)
Right-of-use assets, revaluation surplus	11,000,000	(1,000,000)
Depreciation, right-of-use assets	(91,000,000)	(50,000,000)
Right-Of-Use Assets, Other Increase (Decrease)	0	(4,000,000)
Right-Of-Use Assets, Transfers From Property, Plant, And Equipment			140,000,000
Refining | At cost or in accordance with IFRS 16 within fair value model [member]
Disclosure of quantitative information about leases for lessee [abstract]
Right-of-use assets			70,000,000
Retail and Other
Disclosure of quantitative information about leases for lessee [abstract]
Right-of-use assets	339,000,000	388,000,000	412,000,000
Additions to right-of-use assets	4,000,000	5,000,000
Right-Of-Use Assets, Transfers To Property, Plant, And Equipment	0	0
Right-Of-Use Assets, Disposals And Derecognition	0	2,000,000
Right-of-use assets, revaluation surplus	0	8,000,000
Depreciation, right-of-use assets	(53,000,000)	(39,000,000)
Right-Of-Use Assets, Other Increase (Decrease)	0	0
Right-Of-Use Assets, Transfers From Property, Plant, And Equipment			0
Retail and Other | At cost or in accordance with IFRS 16 within fair value model [member]
Disclosure of quantitative information about leases for lessee [abstract]
Right-of-use assets			$ 412,000,000
Right-of-use assets [member]
Disclosure of quantitative information about leases for lessee [abstract]
Impairment loss (reversal of impairment loss) recognised in profit or loss	411	165
Later than one year
Disclosure of quantitative information about leases for lessee [abstract]
Lease liabilities future payments	195,000,000	205,000,000
Lease Liabilities, Interest	93,000,000	96,000,000
Lease liabilities	102,000,000	109,000,000
After 1 year but no more than 5 years
Disclosure of quantitative information about leases for lessee [abstract]
Lease liabilities future payments	643,000,000	653,000,000
Lease Liabilities, Interest	337,000,000	352,000,000
Lease liabilities	306,000,000	301,000,000
More than 5 years
Disclosure of quantitative information about leases for lessee [abstract]
Lease liabilities future payments	2,031,000,000	2,174,000,000
Lease Liabilities, Interest	1,039,000,000	1,122,000,000
Lease liabilities	$ 992,000,000	$ 1,052,000,000

Goodwill - Goodwill Rollforward

Goodwill - Goodwill Rollforward (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Subclassifications of assets, liabilities and equities [abstract]
Goodwill, beginning balance	$ 656,000,000	$ 690,000,000
Exchange adjustments	13,000,000	(34,000,000)
Impairment loss (reversal of impairment loss) recognised in profit or loss	(11,220)	(2,584)
Goodwill, ending balance	$ 0	$ 656,000,000

Goodwill (Details)

Goodwill (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of reconciliation of changes in goodwill [line items]
Average expected rates of inflation	2.00%	2.00%
Impairment loss (reversal of impairment loss) recognised in profit or loss	$ 11,220	$ 2,584
Average expected rates of inflation	2.00%	2.00%
Recoverable amount of asset or cash-generating unit	$ 6,204
Discount rate used in current measurement of fair value less costs of disposal	1200.00%	1000.00%
Goodwill
Disclosure of reconciliation of changes in goodwill [line items]
Impairment loss (reversal of impairment loss) recognised in profit or loss	$ 669,000,000	$ 0
Recoverable amount of asset or cash-generating unit	$ 0
Discount rate used in current measurement of fair value less costs of disposal	1200.00%	900.00%
Goodwill
Disclosure of reconciliation of changes in goodwill [line items]
Discount rate applied to cash flow projections, term	50 years
Discount rate applied to cash flow projections, term, period one	10 years
Average expected rates of inflation	2.00%	2.00%
Discount rate applied to cash flow projections, term, period two	40 years
Average expected rates of inflation	2.00%	2.00%
Goodwill | Minimum [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Average expected rates of inflation	100.00%
Average expected rates of inflation	100.00%
Goodwill | Maximum [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Average expected rates of inflation	2.00%
Average expected rates of inflation	2.00%

Joint Arrangements - BP-Husky R

Joint Arrangements - BP-Husky Refining LLC (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Contribution Payable
Distribution from joint operation	$ 190	$ 187
Deferred tax assets (note 13)	$ 1,328	$ 0
BP-Husky Refining LLC
Disclosure of joint operations [line items]
Proportion of ownership interest in joint operation	50.00%

Joint Arrangements - Husky-CNOO

Joint Arrangements - Husky-CNOOC Madura Ltd. (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of joint ventures [line items]
Cash and cash equivalents (note 4)	$ 735,000,000	$ 1,775,000,000	$ 2,866,000,000
Results of Operations
Revenues	13,301,000,000	19,902,000,000
Expenses	(25,952,000,000)	(21,897,000,000)
Proportionate share of net loss	(10,016,000,000)	(1,370,000,000)
Equity	7,064,000,000	17,296,000,000
Balance Sheets
Current assets	3,130,000,000	4,938,000,000
Non-current assets	16,557,000,000	28,184,000,000
Current liabilities	(2,392,000,000)	(4,636,000,000)
Total Assets	19,687,000,000	33,122,000,000
Carrying amount in balance sheet	457,000,000	1,182,000,000
Deferred income	37,000,000	152,000,000	205,000,000
Deferred income	37,000,000	152,000,000	$ 205,000,000
Husky-CNOOC Madura Ltd.
Disclosure of joint ventures [line items]
Cash and cash equivalents (note 4)	$ 48,000,000	$ 42,000,000
Share of equity investment	40.00%	40.00%
Results of Operations
Revenues	$ 386,000,000	$ 424,000,000
Expenses	(280,000,000)	(267,000,000)
Proportionate share of net loss	$ 106,000,000	$ 157,000,000
Share of equity investment	40.00%	40.00%
Equity	$ 39,000,000	$ 50,000,000
Balance Sheets
Current assets	215,000,000	208,000,000
Non-current assets	1,657,000,000	1,840,000,000
Current liabilities	(77,000,000)	(70,000,000)
Non-current liabilities	(1,160,000,000)	(1,427,000,000)
Total Assets	$ 635,000,000	$ 551,000,000
Proportion Of Net Assets In Joint Venture	40.00%	40.00%
Carrying amount in balance sheet	$ 457,000,000	$ 516,000,000
Deferred income	$ 8	$ 0
Share of equity investment	40.00%	40.00%
Deferred income	$ 8	$ 0

Joint Arrangements - Husky Mids

Joint Arrangements - Husky Midstream Limited Partnership (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of joint ventures [line items]
Cash and cash equivalents (note 4)	$ 735,000,000	$ 1,775,000,000	$ 2,866,000,000
Results of Operations
Revenues	13,301,000,000	19,902,000,000
Expenses	(25,952,000,000)	(21,897,000,000)
Proportionate share of net loss	(10,016,000,000)	(1,370,000,000)
Equity	7,064,000,000	17,296,000,000
Balance Sheets
Current assets	3,130,000,000	4,938,000,000
Non-current assets	16,557,000,000	28,184,000,000
Current liabilities	(2,392,000,000)	(4,636,000,000)
Total Assets	19,687,000,000	33,122,000,000
Carrying amount in balance sheet	457,000,000	1,182,000,000
Impairment loss (reversal of impairment loss) recognised in profit or loss	11,220	$ 2,584
Recoverable amount of asset or cash-generating unit	$ 6,204
Discount rate used in current measurement of fair value less costs of disposal	1200.00%	1000.00%
Unrecognized Losses from Joint Ventures	$ 7	$ 0
Husky Midstream Limited Partnership
Disclosure of joint ventures [line items]
Cash and cash equivalents (note 4)	30,000,000	86,000,000
Results of Operations
Revenues	322,000,000	316,000,000
Expenses	(206,000,000)	(228,000,000)
Proportionate share of net loss	$ 116,000,000	$ 88,000,000
Share of equity investment	35.00%	35.00%
Equity	$ (32,000,000)	$ 9,000,000
Balance Sheets
Current assets	108,000,000	171,000,000
Non-current assets	3,075,000,000	3,031,000,000
Current liabilities	(30,000,000)	(163,000,000)
Non-current liabilities	(1,175,000,000)	(1,059,000,000)
Total Assets	$ 1,978,000,000	$ 1,980,000,000
Proportion Of Net Assets In Joint Venture	35.00%	35.00%
Carrying amount in balance sheet	$ 0	$ 666,000,000
Power Assets Holding Ltd. | Husky Midstream Limited Partnership
Results of Operations
Share of equity investment	48.75%
Cheung Kong Infrastructure Holdings Ltd. | Husky Midstream Limited Partnership
Results of Operations
Share of equity investment	16.25%
Joint ventures [member]
Balance Sheets
Impairment loss (reversal of impairment loss) recognised in profit or loss	$ 606
Discount rate applied to cash flow projections, term	40 years
Recoverable amount of asset or cash-generating unit	$ 0
Discount rate used in current measurement of fair value less costs of disposal	1200.00%

Joint Arrangements - Sunrise Oi

Joint Arrangements - Sunrise Oil Sands Partnership (Details)	12 Months Ended
	Dec. 31, 2020
Sunrise Oil Sands Partnership
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint operation	50.00%

Other Assets (Details)

Other Assets (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Term Classification [Line Items]
Long-term receivables(1)	$ 130,000,000	$ 489,000,000
Precious metals	21,000,000	22,000,000
Other	15,000,000	13,000,000
Other non-current assets	166,000,000	524,000,000
Receivables by term classification [Table]
Income from reimbursements under insurance policies	85,000,000	630
Later than one year
Term Classification [Line Items]
Receivables and payables related to insurance contracts	98,000,000	435,000,000
Receivables and payables related to insurance contracts	$ 98,000,000	$ 435,000,000

Bank Operating Loans (Details)

Bank Operating Loans (Details) - CAD ($)	Dec. 31, 2020	Dec. 31, 2019
Disclosure of detailed information about borrowings [line items]
Line of credit, maximum borrowing capacity	$ 4,975,000,000
Line of credit, maximum borrowing capacity	4,975,000,000
Bank operating loan
Disclosure of detailed information about borrowings [line items]
Line of credit, maximum borrowing capacity	975,000,000	$ 900,000,000
Letter of credit, maximum borrowing capacity	427,000,000	436,000,000
Unsecured bank loans received	40,000,000	0
Line of credit, maximum borrowing capacity	975,000,000	900,000,000
Demand facilities available for letters of credit [Member]
Disclosure of detailed information about borrowings [line items]
Line of credit, maximum borrowing capacity	125
Line of credit, maximum borrowing capacity	125
Sunrise Oil Sands Partnership | Unsecured demand credit facility
Disclosure of detailed information about borrowings [line items]
Line of credit, maximum borrowing capacity	10,000,000	10,000,000
Line of credit, maximum borrowing capacity	10,000,000	10,000,000
Husky Energy Inc. | Sunrise Oil Sands Partnership | Unsecured demand credit facility
Disclosure of detailed information about borrowings [line items]
Line of credit, maximum borrowing capacity	5,000,000	5,000,000
Line of credit, maximum borrowing capacity	$ 5,000,000	$ 5,000,000

Accounts Payable and Accrued _3

Accounts Payable and Accrued Liabilities (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Subclassifications of assets, liabilities and equities [abstract]
Trade payables	$ 772	$ 1,178
Accrued liabilities	1,115	1,954
Dividend payable (note 20)	13	126
Stock-based compensation	22	19
Derivatives due within one year	31	21
Other	176	167
Accounts payable and accrued liabilities	$ 2,129	$ 3,465

Debt and Credit Facilities - Sh

Debt and Credit Facilities - Short-term Debt (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Disclosure of borrowing costs [Abstract]
Commercial paper	$ 0	$ 550
Bank acceptance liabilities	$ 40	$ 0
Commercial paper
Disclosure of detailed information about borrowings [line items]
Interest rate, weighted average		1.98%

Debt and Credit Facilities - Lo

Debt and Credit Facilities - Long-term Debt (Details)	Mar. 12, 2020CAD ($)	Dec. 16, 2019USD ($)	Jun. 17, 2019USD ($)	Dec. 31, 2020CAD ($)	Dec. 31, 2020USD ($)	Aug. 07, 2020	Dec. 31, 2019CAD ($)	Dec. 31, 2019USD ($)	Mar. 15, 2019
Disclosure of detailed information about borrowings [line items]
Long-term debt				$ 6,117,000,000	$ 2,387,000,000		$ 4,570,000,000	$ 2,387,000,000
Long-term debt due within one year				0			400,000,000
Long-term debt (note 15)				6,117,000,000	$ 2,387,000,000		4,570,000,000	2,387,000,000
Long-term debt due within one year (note 17)				0			400,000,000
Line of credit, maximum borrowing capacity				$ 4,975,000,000
6.15% Notes Due 2019
Disclosure of detailed information about borrowings [line items]
Interest rate			615.00%
Long-term debt repayment			$ 402
Interest rate, weighted average			615.00%
7.25% Notes Due 2019
Disclosure of detailed information about borrowings [line items]
Interest rate		725.00%
Long-term debt repayment		$ 987
Interest rate, weighted average		725.00%
5.00% Notes Due 2020
Disclosure of detailed information about borrowings [line items]
Interest rate		500.00%		5.00%	5.00%
Long-term debt repayment	$ 400
Interest rate, weighted average		500.00%		5.00%	5.00%
3.95% Notes Due 2022
Disclosure of detailed information about borrowings [line items]
Interest rate				3.95%	3.95%
Interest rate, weighted average				3.95%	3.95%
4.00 Notes Due 2024
Disclosure of detailed information about borrowings [line items]
Interest rate				4.00%	4.00%
Interest rate, weighted average				4.00%	4.00%
3.55% Notes Due 2025
Disclosure of detailed information about borrowings [line items]
Interest rate				3.55%	3.55%
Interest rate, weighted average				3.55%	3.55%
3.60% Notes Due 2027
Disclosure of detailed information about borrowings [line items]
Interest rate				3.60%	3.60%
Interest rate, weighted average				3.60%	3.60%
6.80% Notes Due 2037
Disclosure of detailed information about borrowings [line items]
Interest rate				6.80%	6.80%
Interest rate, weighted average				6.80%	6.80%
Non-current debt due within one year [Member]
Disclosure of detailed information about borrowings [line items]
Long-term debt due within one year							400,000,000
Long-term debt due within one year (note 17)							400,000,000
Three Point Five Percent Notes Due 2028
Disclosure of detailed information about borrowings [line items]
Interest rate				3.50%	3.50%	350.00%
Interest rate, weighted average				3.50%	3.50%	350.00%
Four Point Four Percent Notes Due 2029
Disclosure of detailed information about borrowings [line items]
Interest rate				4.40%	4.40%				440.00%
Interest rate, weighted average				4.40%	4.40%				440.00%
Cost | 5.00% Notes Due 2020
Disclosure of detailed information about borrowings [line items]
Interest rate				0.0005%	0.0005%
Interest rate, weighted average				0.0005%	0.0005%
Cost | 3.95% Notes Due 2022
Disclosure of detailed information about borrowings [line items]
Long-term debt				$ 637,000,000	$ 500,000,000		648,000,000	500,000,000
Interest rate				0.0004%	0.0004%
Long-term debt (note 15)				$ 637,000,000	$ 500,000,000		648,000,000	500,000,000
Interest rate, weighted average				0.0004%	0.0004%
Cost | 4.00 Notes Due 2024
Disclosure of detailed information about borrowings [line items]
Long-term debt				$ 957,000,000	$ 750,000,000		973,000,000	750,000,000
Interest rate				0.0004%	0.0004%
Long-term debt (note 15)				$ 957,000,000	$ 750,000,000		973,000,000	750,000,000
Interest rate, weighted average				0.0004%	0.0004%
Cost | 3.55% Notes Due 2025
Disclosure of detailed information about borrowings [line items]
Long-term debt				$ 750,000,000	$ 0		750,000,000	0
Interest rate				0.00036%	0.00036%
Long-term debt (note 15)				$ 750,000,000	$ 0		750,000,000	0
Interest rate, weighted average				0.00036%	0.00036%
Cost | 3.60% Notes Due 2027
Disclosure of detailed information about borrowings [line items]
Long-term debt				$ 750,000,000	$ 0		750,000,000	0
Interest rate				0.00036%	0.00036%
Long-term debt (note 15)				$ 750,000,000	$ 0		750,000,000	0
Interest rate, weighted average				0.00036%	0.00036%
Cost | 6.80% Notes Due 2037
Disclosure of detailed information about borrowings [line items]
Long-term debt				$ 493,000,000	$ 387,000,000		501,000,000	387,000,000
Interest rate				0.00068%	0.00068%
Long-term debt (note 15)				$ 493,000,000	$ 387,000,000		501,000,000	387,000,000
Interest rate, weighted average				0.00068%	0.00068%
Cost | Syndicated Credit Facilities
Disclosure of detailed information about borrowings [line items]
Long-term debt				$ 350,000,000	$ 0		0	0
Long-term debt (note 15)				350,000,000	0		0	0
Cost | Three Point Five Percent Notes Due 2028
Disclosure of detailed information about borrowings [line items]
Long-term debt				$ 1,250,000,000	$ 0		0	0
Interest rate				0.00035%	0.00035%
Long-term debt (note 15)				$ 1,250,000,000	$ 0		0	0
Interest rate, weighted average				0.00035%	0.00035%
Cost | Four Point Four Percent Notes Due 2029
Disclosure of detailed information about borrowings [line items]
Long-term debt				$ 957,000,000	$ 750,000,000		973,000,000	750,000,000
Interest rate				0.00044%	0.00044%
Long-term debt (note 15)				$ 957,000,000	$ 750,000,000		973,000,000	750,000,000
Interest rate, weighted average				0.00044%	0.00044%
Deferred financing costs
Disclosure of detailed information about borrowings [line items]
Long-term debt				$ 27,000,000	$ 0		25,000,000	0
Long-term debt (note 15)				27,000,000	$ 0		25,000,000	$ 0
Non-current debt due within one year [Member]
Disclosure of detailed information about borrowings [line items]
Long-term debt due within one year				0			400,000,000
Long-term debt repayment				(1,400,000,000)
Long-term debt due within one year (note 17)				$ 0			$ 400,000,000

Debt and Credit Facilities - Cr

Debt and Credit Facilities - Credit Facilities (Details) - CAD ($)	Dec. 31, 2020	Dec. 31, 2019
Disclosure of detailed information about borrowings [line items]
Line of credit, maximum borrowing capacity	$ 4,975,000,000
Borrowings, maximum borrowing capacity	4,975,000,000
Line of credit, maximum borrowing capacity	4,975,000,000
Revolving syndicated credit facility, March 9, 2020
Disclosure of detailed information about borrowings [line items]
Line of credit, maximum borrowing capacity	2,000,000,000
Borrowings, maximum borrowing capacity	2,000,000,000
Borrowings	350,000,000	$ 0
Line of credit, maximum borrowing capacity	2,000,000,000
Revolving syndicated credit facility, June 19, 2022
Disclosure of detailed information about borrowings [line items]
Line of credit, maximum borrowing capacity	2,000,000,000
Borrowings, maximum borrowing capacity	2,000,000,000
Borrowings	0	$ 0
Line of credit, maximum borrowing capacity	2,000,000,000
Unsecured Non-Revolving Term Credit Facility [Member]
Disclosure of detailed information about borrowings [line items]
Line of credit, maximum borrowing capacity	500
Borrowings, maximum borrowing capacity	500
Line of credit, maximum borrowing capacity	$ 500

Debt and Credit Facilities - No

Debt and Credit Facilities - Notes (Details)	Aug. 07, 2020CAD ($)	Mar. 12, 2020CAD ($)	Dec. 16, 2019USD ($)	Jun. 17, 2019USD ($)	Dec. 31, 2020CAD ($)	Dec. 31, 2020USD ($)	Aug. 07, 2020USD ($)	Mar. 03, 2020USD ($)	May 01, 2019CAD ($)	Mar. 15, 2019USD ($)
Disclosure of detailed information about borrowings [line items]
Authorized Capital Commitments, Pre-Registration					$ 1.75	$ 3
Debt and Credit Facilities					Debt and Credit Facilities Short-term Debt December 31, 2020 December 31, 2019 ($ millions) Commercial paper (1) — 550 Bankers' Acceptances 40 — (1) The weighted average interest rate as at December 31, 2019 was 1.98% per annum. Canadian $ Amount U.S. $ Denominated Long-term Debt Maturity December 31, 2020 December 31, 2019 December 31, 2020 December 31, 2019 ($ millions) Long-term debt Syndicated Credit Facility 2022 350 — — — 3.95% notes (1)(3) 2022 637 648 500 500 4.00% notes (1)(3) 2024 957 973 750 750 3.55% notes (4) 2025 750 750 — — 3.60% notes (4) 2027 750 750 — — 3.50% notes (4) 2028 1,250 — — — 4.40% notes (1)(3) 2029 957 973 750 750 6.80% notes (1)(3) 2037 493 501 387 387 Debt issue costs (2) (27) (25) — — Long-term debt 6,117 4,570 2,387 2,387 Long-term debt due within one year 5.00% notes (4) 2020 — 400 — — Long-term debt due within one year — 400 — — (1) The U.S. dollar denominated debt is designated as a hedge of the Company’s net investment in selected foreign operations with a U.S. dollar functional currency. Refer to Note 25 for Foreign Currency Risk Management. (2) Calculated using the effective interest rate method. (3) The 3.95%, the 4.00%, the 4.40% and the 6.80% notes represent unsecured securities under a trust indenture dated September 11, 2007. (4) The 5.00%, the 3.55%, the 3.60% and the 3.50% notes represent unsecured securities under a trust indenture dated December 21, 2009. Credit Facilities On April 7, 2020 the Company entered into a $500 million unsecured non-revolving term credit facility. Interest payable is based on pricing referenced to CAD Bankers’ Acceptance or CAD Prime Rates. The facility was repaid on October 5, 2020. As at December 31, 2020 the covenant under the Company’s credit facilities was a debt to capital ratio, calculated as total debt (long-term debt including long-term debt due within one year and short-term debt) and certain adjusting items specified in the credit agreements divided by total debt and shareholders’ equity. This covenant is used to assess the Company’s financial strength. If the Company does not comply with the covenant under the credit facilities, there is risk that repayment could be accelerated. The Company was in compliance with this covenant under its credit facilities at December 31, 2020, and assessed the risk of non-compliance to be low. As at December 31, 2020, the Company had $350 million outstanding under its $2.0 billion committed syndicated credit facility expiring June 19, 2022 (December 31, 2019 – no direct borrowings), and no direct borrowings under its $2.0 billion committed syndicated credit facility expiring March 9, 2024 (December 31, 2019 – no direct borrowings). Interest payable is based on Bankers’ Acceptance, CAD Prime Rate, U.S. LIBOR, or U.S. Base Rates, depending on the borrowing option selected and credit ratings assigned by certain credit rating agencies to the Company. Notes On March 15, 2019, the Company issued US$750 million in senior unsecured notes. The notes bear an annual interest rate of 4.40% and are due on April 15, 2029. The Company raised the net proceeds of the offering for general corporate purposes, which included the repayment of certain outstanding debt securities that matured in 2019. On May 1, 2019, the Company filed a universal short form base shelf prospectus (the “2019 Canadian Shelf Prospectus”) with applicable securities regulators in each of the provinces of Canada that enabled the Company to offer up to $3.0 billion of common shares, preferred shares, debt securities, subscription receipts, warrants and other units in Canada. As a result of the delisting of Husky's shares from the TSX, the Company is unable to sell securities under the 2019 Canadian Shelf Prospectus. On June 17, 2019, the Company repaid the maturing 6.15% notes. The amount paid to note holders was $402 million. On December 16, 2019, the Company repaid the maturing 7.25% notes. The amount paid to note holders was $987 million. On March 3, 2020, the Company filed a universal short form base shelf prospectus (the "2020 U.S. Shelf Prospectus”) with the Alberta Securities Commission. On March 4, 2020, the Company’s related U.S. registration statement filed with the SEC containing the 2020 U.S. Shelf Prospectus became effective which enabled the Company to offer up to US$3.0 billion of debt securities, common shares, preferred shares, subscription receipts, warrants and units of the Company in the U.S. During the period that the 2020 U.S. Shelf Prospectus and the related U.S registration statement were effective, securities could be offered in amounts, at prices and on terms set forth in a prospectus supplement. On January 26, 2021, the Company terminated the effectiveness of the U.S. registration statement. On March 12, 2020, the Company repaid the maturing 5.00% notes. The principal paid to note holders was $400 million. On August 7, 2020, the Company issued $1.25 billion of notes. The notes have a coupon of 3.50% and are due on February 7, 2028. Proceeds were for general corporate purposes, which included the repayment of Husky’s $500 million unsecured non-revolving term loan credit facility on October 5, 2020. At December 31, 2020, the Company had unused capacity of $1.75 billion under the 2019 Canadian Shelf Prospectus and US$3.0 billion under the 2020 U.S. Shelf Prospectus and related U.S. registration statement. The Company’s notes, credit facilities and short-term lines of credit rank equally in right of payment. Reconciliation of Changes of Liabilities to Cash Flows from Financing Activities Liabilities ($ millions) Short-term debt Long-term debt due within one year Long-term debt Other long-term liabilities Lease liabilities due within one year Lease liabilities December 31, 2019 550 400 4,570 454 109 1,353 Changes from financing cash flows Long-term debt issuance, net — (1,400) 2,600 — — — Short-term debt issuance, net (510) — — — — — Debt issue costs — — (7) — — — Finance lease payments — — — — (111) — Total change from financing cash flows (510) (1,400) 2,593 — (111) — Other changes – liability-related Foreign exchange — — — (1) — — Fair value changes — — — 8 — 32 Net additions of lease liabilities — — — — — 23 Reclassification — 1,000 (1,000) — 107 (107) Deferred revenue — — — (115) — — Amortization of debt issuance costs — — 4 — — — Foreign exchange recognized in OCI — — (50) — (1) (2) Other — — — 64 (2) (1) Total other changes – liability related — 1,000 (1,046) (44) 104 (55) December 31, 2020 40 — 6,117 410 102 1,298
Four Point Four Percent Notes Due 2029
Disclosure of detailed information about borrowings [line items]
Interest rate					4.40%	4.40%				440.00%
Borrowings										$ 750
Unsecured bank loans received										$ 750
Interest rate, weighted average					4.40%	4.40%				440.00%
6.15% Notes Due 2019
Disclosure of detailed information about borrowings [line items]
Interest rate				615.00%
Long-term debt repayment				$ 402
Interest rate, weighted average				615.00%
Long-term debt repayment				$ 402
7.25% Notes Due 2019
Disclosure of detailed information about borrowings [line items]
Interest rate			725.00%
Long-term debt repayment			$ 987
Interest rate, weighted average			725.00%
Long-term debt repayment			$ 987
5.00% Notes Due 2020
Disclosure of detailed information about borrowings [line items]
Interest rate			500.00%		5.00%	5.00%
Long-term debt repayment		$ 400
Interest rate, weighted average			500.00%		5.00%	5.00%
Long-term debt repayment		$ 400
Three Point Five Percent Notes Due 2028
Disclosure of detailed information about borrowings [line items]
Interest rate					3.50%	3.50%	350.00%
Borrowings							$ 1.25
Unsecured bank loans received							$ 1.25
Interest rate, weighted average					3.50%	3.50%	350.00%
Unsecured Non-Revolving Term Credit Facility [Member]
Disclosure of detailed information about borrowings [line items]
Long-term debt repayment	$ 500
Long-term debt repayment	$ 500
2019 Canadian Shelf Prospectus [Member]
Disclosure of detailed information about borrowings [line items]
Authorized Capital Commitments, Pre-Registration					$ 1.75				$ 3
2020 U.S. Shelf Prospectus
Disclosure of detailed information about borrowings [line items]
Authorized Capital Commitments, Pre-Registration						$ 3		$ 3

Debt and Credit Facilities - Re

Debt and Credit Facilities - Reconciliation of Changes of Liabilities to Cash Flows from Financing Activities (Details) $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020CAD ($)	Dec. 31, 2019CAD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Disclosure of detailed information about borrowings [line items]
Long-term debt due within one year (note 17)	$ 0	$ 400
Long-term debt (note 15)	6,117	4,570	$ 2,387	$ 2,387
Long-term debt issuance (repayment) (note 17)	1,200	(389)
Payments of finance lease liabilities, classified as financing activities	208	339
Current lease liabilities	102	109
Non-current lease liabilities	1,298	1,353
Hedge of net investment (note 25)	44	146
Other	2	(1)
Short-term debt	40
Long-term debt due within one year	0	400
Long-term debt	6,117	4,570	$ 2,387	$ 2,387
Other non-current financial liabilities	410	454
Long-term debt issuance, net	1,200	(389)
Debt issue costs	(7)	(9)
Payment of finance lease obligations	(208)	(339)
Deferred revenue	(115)	(42)
Foreign exchange recognized in OCI	(44)	(146)
Non-current debt due within one year [Member]
Disclosure of detailed information about borrowings [line items]
Long-term debt due within one year (note 17)	0	400
Long-term debt issuance (repayment) (note 17)	(1,400)
Increase Decrease Through Reclassification From Long Term Debt To Current Portion Of Long Term Debt Liabilities Arising From Financing Activities	1,000
Hedge of net investment (note 25)	0
Long-term debt due within one year	0	400
Long-term debt issuance, net	(1,400)
Repayments of non-current borrowings	1,400
Total other changes - liability related, Current portion of non-current borrowings	1,000
Foreign exchange recognized in OCI	0
Long-term debt
Disclosure of detailed information about borrowings [line items]
Long-term debt (note 15)	6,117	4,570
Long-term debt issuance (repayment) (note 17)	2,600
Increase Decrease Through Reclassification From Long Term Debt To Current Portion Of Long Term Debt Liabilities Arising From Financing Activities	(1,000)
Hedge of net investment (note 25)	50
Long-term debt	6,117	4,570
Long-term debt issuance, net	2,600
Debt issue costs	7
Proceeds from non-current borrowings, net of debt issuance costs	2,593
Adjustments for finance costs	4
Foreign exchange recognized in OCI	(50)
Total other changes - liability related, Long-term debt	1,046
Current Lease Liabilities
Disclosure of detailed information about borrowings [line items]
Payments of finance lease liabilities, classified as financing activities	(111)
Current lease liabilities	102	109
Increase Decrease Through Reclassification From Long Term Debt To Current Portion Of Long Term Debt Liabilities Arising From Financing Activities	107
Hedge of net investment (note 25)	1
Other	(2)
Total other changes - liability related, Other long-term liabilities	104
Payment of finance lease obligations	111
Foreign exchange recognized in OCI	(1)
Non-current Lease Liabilities
Disclosure of detailed information about borrowings [line items]
Non-current lease liabilities	1,298	1,353
Net Addition Lease Liabilities	23
Increase Decrease Through Reclassification From Long Term Debt To Current Portion Of Long Term Debt Liabilities Arising From Financing Activities	(107)
Fair value changes	32
Hedge of net investment (note 25)	2
Other	(1)
Total other changes - liability related, Other long-term liabilities	(55)
Foreign exchange recognized in OCI	(2)
Short-term borrowings [member]
Disclosure of detailed information about borrowings [line items]
Repayments of current borrowings	(510)
Short-term debt	40	550
Other long-term liabilities [Member]
Disclosure of detailed information about borrowings [line items]
Fair value changes	8
Other	64
Total other changes - liability related, Other long-term liabilities	(44)
Other non-current financial liabilities	410	454
Foreign exchange, other long-term liabilities	(1)
Net additions of lease liabilities	$ (115)
Non-current debt due within one year [Member]
Disclosure of detailed information about borrowings [line items]
Long-term debt due within one year (note 17)		400
Long-term debt due within one year		$ 400

Asset Retirement Obligations -

Asset Retirement Obligations - Carrying amount of ARO (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of other provisions [line items]
Asset Retirement Obligations, Expected to be incurred within 1 year	$ 94	$ 112
Asset Retirement Obligations, Expected to be incurred beyond 1 year	2,068	2,643
Asset Retirement Obligations
Disclosure of other provisions [line items]
Asset Retirement Obligation, Beginning balance	2,755	2,424
Additions	63	76
Liabilities settled	(39)	(276)
Liabilities disposed	(39)	(6)
Change in discount rate	(544)	285
Change in estimates	(146)	156
Exchange adjustment	8	(10)
Accretion (note 21)	104	106
Asset Retirement Obligation, Ending balance	$ 2,162	$ 2,755
Expected timing	45 years	45 years

Asset Retirement Obligations _2

Asset Retirement Obligations - Narrative (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of other provisions [line items]
Average expected rates of inflation	2.00%	2.00%
Restricted cash (notes 7, 18)	$ 164	$ 142
Asset Retirement Obligations
Disclosure of other provisions [line items]
Undiscounted inflation-adjusted ARO	$ 9,500	$ 10,000
Expected timing	45 years	45 years
Peoples Republic of China
Disclosure of other provisions [line items]
Restricted cash and cash equivalents	$ 164	$ 142
Minimum | Asset Retirement Obligations
Disclosure of other provisions [line items]
Discount rate, adjusted risk-free rate (as a percent)	3.60%	3.90%
Maximum | Asset Retirement Obligations
Disclosure of other provisions [line items]
Discount rate, adjusted risk-free rate (as a percent)	6.20%	4.40%

Other Long-term Liabilities - O

Other Long-term Liabilities - Other Long-Term Liabilities (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Subclassifications of assets, liabilities and equities [abstract]
Employee future benefits (note 23)	$ 233	$ 214
Non-current lease liabilities	1,298	1,353
Stock-based compensation	19	19
Deferred revenue	37	152
Other	121	69
Other non-current financial liabilities	$ 410	$ 454

Other Long-term Liabilities - D

Other Long-term Liabilities - Deferred Revenue (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Deferred Revenue [Line Items]
Deferred income	$ 37	$ 152	$ 205
Decrease through performance obligation being satisfied, contract liabilities	(115)	(42)
Increase (decrease) through net exchange difference, deferred revenue liability	$ 0	$ (11)

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of income tax [Abstract]
Current income tax charge	$ 183,000,000	$ 174,000,000
Adjustments to current income tax estimates	19,000,000	1,000,000
Provisions for (recovery of) income taxes. current	202,000,000	175,000,000
Relating to origination and reversal of temporary differences	(3,248,000,000)	(723,000,000)
Adjustments to deferred income tax estimates	58,000,000	(251,000,000)
Provisions for (recovery of) income taxes, deferred	(3,190,000,000)	(974,000,000)
Recovery of income taxes from Impairment of non-current assets	2,654
Impairment loss (reversal of impairment loss) recognised in profit or loss	$ 11,220	$ 2,584

Income Taxes - Deferred Tax Ite

Income Taxes - Deferred Tax Items in OCI (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income tax relating to components of other comprehensive income [abstract]
Derivatives designated as cash flow hedges	$ (3)	$ (3)
Remeasurement of pension plans	(2)	1
Exchange differences on translation of foreign operations	29	(58)
Hedge of net investment	6	30
Income tax relating to components of other comprehensive income	$ 30	$ (30)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Effective Tax Rate (Details) - CAD ($)	12 Months Ended		24 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020
Disclosure of geographical areas [line items]
Average effective tax rate	24.90%	26.80%
Reconciliation of Effective Tax Rate
Earnings before income taxes	$ (13,004,000,000)	$ (2,169,000,000)
Expected income tax	(3,238,000,000)	(582,000,000)
Tax effect capital gains	1,000,000	0
Foreign jurisdictions	202,000,000	61,000,000
Non-taxable items	(16,000,000)	(25,000,000)
Adjustments with respect to previous year	77,000,000	(250,000,000)
Revaluation of foreign tax pools	(12,000,000)	(4,000,000)
Other – net	(2,000,000)	1,000,000
Provisions for (recovery of) income taxes	(2,988,000,000)	(799,000,000)
Tax effect capital gains	1,000,000	0
Deferred tax assets (note 13)	1,328,000,000	0	$ 1,328,000,000
Canada
Reconciliation of Effective Tax Rate
Earnings before income taxes	(8,799,000,000)	(3,170,000,000)
Deferred tax assets (note 13)	803		803
United States
Reconciliation of Effective Tax Rate
Earnings before income taxes	(4,969,000,000)	337,000,000
Deferred tax assets (note 13)	187		$ 187
Other foreign jurisdictions
Reconciliation of Effective Tax Rate
Earnings before income taxes	$ 764,000,000	$ 664,000,000
ALBERTA
Disclosure of geographical areas [line items]
Applicable tax rate		1000.00%	800.00%
Reconciliation of Effective Tax Rate
Applicable tax rate		1000.00%	800.00%
Tax rate effect from change in tax rate	200.00%

Income Taxes - Deferred Tax Lia

Income Taxes - Deferred Tax Liabilities and Assets (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax liabilities	$ (338,000,000)	$ (2,170,000,000)
Deferred tax assets	(1,328,000,000)	0
Deferred tax liability	990,000,000	(2,170,000,000)	$ (3,174,000,000)
Deferred income taxes	3,190,000,000	974,000,000
Income tax relating to components of other comprehensive income	(30,000,000)	30,000,000
Deferred tax assets (note 13)	1,328,000,000	0
Net deferred tax assets	1,328,000,000	0
Canada
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax assets	(803)
Deferred tax assets (note 13)	803
Net deferred tax assets	1,127,000,000	0
United States
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax assets	(187)
Deferred tax assets (note 13)	187
Net deferred tax assets	187,000,000	0
Exploration and evaluation assets and property, plant and equipment
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax liabilities	(489,000,000)	(3,053,000,000)	(4,089,000,000)
Deferred income taxes	2,578,000,000	967,000,000
Income tax relating to components of other comprehensive income	(14,000,000)	69,000,000
Foreign exchange gains taxable on realization
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax liabilities	(3,000,000)	(150,000,000)	(174,000,000)
Deferred income taxes	151,000,000	51,000,000
Income tax relating to components of other comprehensive income	(4,000,000)	(27,000,000)
Debt issue costs
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax liabilities	(5,000,000)	(5,000,000)	(4,000,000)
Deferred income taxes	0	(1,000,000)
Income tax relating to components of other comprehensive income	0	0
Other temporary differences
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax liabilities	(101,000,000)	(152,000,000)	(28,000,000)
Deferred income taxes	51,000,000	(124,000,000)
Income tax relating to components of other comprehensive income	0	0
Pension plans
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax assets	(28,000,000)	(16,000,000)	(8,000,000)
Deferred income taxes	10,000,000	9,000,000
Income tax relating to components of other comprehensive income	2,000,000	(1,000,000)
Deferred tax assets (note 13)	28,000,000	16,000,000	8,000,000
Asset retirement obligations
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax assets	(526,000,000)	(666,000,000)	(654,000,000)
Deferred income taxes	(138,000,000)	16,000,000
Income tax relating to components of other comprehensive income	(2,000,000)	(4,000,000)
Deferred tax assets (note 13)	526,000,000	666,000,000	654,000,000
Loss carry-forwards
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax assets	(1,041,000,000)	(517,000,000)	(468,000,000)
Deferred income taxes	536,000,000	56,000,000
Income tax relating to components of other comprehensive income	(12,000,000)	(7,000,000)
Deferred tax assets (note 13)	1,041,000,000	517,000,000	468,000,000
Financial assets at fair value
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax assets	7,000,000	9,000,000	9,000,000
Deferred income taxes	2,000,000	0
Income tax relating to components of other comprehensive income	0	0
Deferred tax assets (note 13)	(7,000,000)	(9,000,000)	$ (9,000,000)
Foreign subsidiaries, branches and interest in join ventures
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax liabilities	0	0
Unused tax losses, expire between 2030 and 2037
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax assets	(4,401,000,000)	(2,105,000,000)
Deferred tax assets (note 13)	$ 4,401,000,000	$ 2,105,000,000

Share Capital - Common Shares (

Share Capital - Common Shares (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Equity, ending, shares	1,005,121,738
Issued capital, ending balance (in shares)	$ 7,293,000,000
Dividend payables (in CAD per share)	13	$ 126,000,000
Dividends declared on common shares	163,000,000	503,000,000
Dividends recognised as distributions to owners	$ 276,000,000	503,000,000
Preference shares [member]
Disclosure of classes of share capital [line items]
Equity, ending, shares	36,000,000
Issued capital, ending balance (in shares)	$ 874,000,000
Dividend payables (in CAD per share)	0	0
Dividends declared on common shares	35,000,000	35,000,000
Dividends recognised as distributions to owners	$ 35,000,000	$ 35,000,000

Share Capital - Preferred Share

Share Capital - Preferred Shares (Details) - shares	Dec. 31, 2020	Mar. 01, 2020
Disclosure of classes of share capital [line items]
Series 5 Preferred Shares Tendered For Conversion		40,800
Preference shares [member]
Disclosure of classes of share capital [line items]
Equity, shares	36,000,000

Share Capital - Preferred Sha_2

Share Capital - Preferred Shares Textual (Details)	12 Months Ended
	Dec. 31, 2020CAD ($)	Nov. 24, 2020	Jun. 30, 2020	Jun. 01, 2020CAD ($)	Mar. 31, 2020	Mar. 01, 2020shares	Dec. 31, 2019CAD ($)
Disclosure of classes of share capital [line items]
Five Year Government of Canada Bond Yield [Member]			0.415		1.021
Series 5 Preferred Shares Tendered For Conversion | shares						40,800
Series 7 Shares Tendered for Conversion				$ 212,461
Preference shares [member]
Disclosure of classes of share capital [line items]
Dividend payables	$ 0						$ 0
Redeemable preferred shares, series 1 preferred shares
Disclosure of classes of share capital [line items]
Dividend yield, quarterly	2.404%
Dividend yield, term	5 years
Dividend yield, term two	5 years
Dividend yield, quarterly	2.404%
Redeemable preferred shares, series 2 preferred shares
Disclosure of classes of share capital [line items]
Dividend yield, term	5 years
Dividend yield, term two	3 months
Conversion conditions, term	5 years
Redeemable preferred shares, series 3 preferred shares
Disclosure of classes of share capital [line items]
Dividend yield, quarterly	4.689%
Dividend yield, term two	5 years
Dividend yield, quarterly	4.689%
Redeemable preferred shares, series 4 preferred shares
Disclosure of classes of share capital [line items]
Dividend yield, term two	5 years
Government of Canada Bond | Redeemable preferred shares, series 1 preferred shares
Disclosure of classes of share capital [line items]
Dividend rate, basis spread on variable rate	1.73%
Debt instrument, term	5 years
Dividend rate, basis spread on variable rate	1.73%
Government of Canada Bond | Redeemable preferred shares, series 3 preferred shares
Disclosure of classes of share capital [line items]
Dividend rate, basis spread on variable rate	3.13%
Debt instrument, term	5 years
Dividend rate, basis spread on variable rate	3.13%
90-day Government of Canada Treasury Bills | Redeemable preferred shares, series 2 preferred shares
Disclosure of classes of share capital [line items]
Dividend rate, basis spread on variable rate	188.70%	1.73%
Dividend rate, basis spread on variable rate	188.70%	1.73%
90-day Government of Canada Treasury Bills | Redeemable preferred shares, series 4 preferred shares
Disclosure of classes of share capital [line items]
Dividend rate, basis spread on variable rate	3.13%
Dividend rate, basis spread on variable rate	3.13%
90-day Government of Canada Treasury Bills | Redeemable preferred shares, series 5 preferred shares
Disclosure of classes of share capital [line items]
Dividend rate, basis spread on variable rate					357.00%
Dividend rate, basis spread on variable rate					357.00%
90-day Government of Canada Treasury Bills | Redeemable preferred shares, series 7 preferred shares
Disclosure of classes of share capital [line items]
Dividend rate, basis spread on variable rate			352.00%
Dividend rate, basis spread on variable rate			352.00%

Share Capital - Redeemable Pref

Share Capital - Redeemable Preferred Shares Dividends (Details) - Preference shares [member] - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of classes of share capital [line items]
Dividends declared on preferred shares	$ 35	$ 35
Dividends recognised as distributions to owners	35	35
Series 1 Preferred Shares
Disclosure of classes of share capital [line items]
Dividends declared on preferred shares	6	6
Dividends recognised as distributions to owners	6	6
Series 2 Preferred Shares
Disclosure of classes of share capital [line items]
Dividends declared on preferred shares	1	1
Dividends recognised as distributions to owners	1	1
Series 3 Preferred Shares
Disclosure of classes of share capital [line items]
Dividends declared on preferred shares	12	12
Dividends recognised as distributions to owners	12	12
Series 5 Preferred Shares
Disclosure of classes of share capital [line items]
Dividends declared on preferred shares	9	9
Dividends recognised as distributions to owners	9	9
Series 7 Preferred Shares
Disclosure of classes of share capital [line items]
Dividends declared on preferred shares	7	7
Dividends recognised as distributions to owners	$ 7	$ 7

Share Capital - Stock Option Pl

Share Capital - Stock Option Plan (Details)	12 Months Ended
	Dec. 31, 2020CAD ($)year	Dec. 31, 2019CAD ($)year
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share option, term | year	1.99	1.97
Stock based compensation expense	$ 16,000,000	$ (2,000,000)
Weighted average fair value (in CAD per option)	$ 0.87	0.25
Stock Option Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share option, term | year	5
Liabilities from share-based payment transactions	$ 13,000,000	4,000,000
Stock based compensation expense	9,000,000	(6,000,000)
Stock option exercisable, intrinsic value	9,000,000
Weighted average fair value (in CAD per option)	$ 0.36	$ 2.34

Share Capital - Outstanding and

Share Capital - Outstanding and Exercisable Options (Details)	12 Months Ended
	Dec. 31, 2020CAD ($)shares$ / shares	Dec. 31, 2019CAD ($)shares$ / shares
Disclosure of share capital, reserves and other equity interest [Abstract]
Number of stock options outstanding, beginning of year (in options) | shares	18,498,000	19,967,000
Number of stock options granted (in options) | shares	6,113,000	4,241,000
Number of share options surrendered for cash (in options) | shares	0	(4,000)
Number of stock options expired or forfeited (in options) | shares	(5,728,000)	(5,706,000)
Number of stock options outstanding, end of year (in options) | shares	18,883,000	18,498,000
Number of stock options exercisable, end of year (in options) | shares	9,651,000	10,596,000
Weighted average exercise price of stock options outstanding, beginning of year (in cad per option) | $ / shares	$ 17.75	$ 21.48
Weighted average exercise price of stock options granted (in cad per option) | $ / shares	2.86	14.31
Weighted average exercise price of share options surrendered for cash (in cad per option) | $ / shares	0	15.67
Weighted average exercise price of stock options expired/forfeited (in cad per option) | $ / shares	20.78	28.27
Weighted average exercise price of stock options outstanding, end of year (in cad per option) | $ / shares	12.01	17.75
Weighted average exercise price of options exercisable (in cad per option) | $ / shares	$ 16.11	$ 19.27
Weighted average fair value (in CAD per option) | $	$ 0.87	$ 0.25

Share Capital - Outstanding a_2

Share Capital - Outstanding and Exercisable Options-Range of Exercise Prices (Details)	12 Months Ended
	Dec. 31, 2020shares$ / shares	Dec. 31, 2019shares$ / shares	Dec. 31, 2018shares$ / shares
Disclosure of range of exercise prices of outstanding share options [line items]
Number of options outstanding (in options) | shares	18,883,000	18,498,000	19,967,000
Weighted average exercise price of stock options outstanding (in cad per option)	$ 12.01	$ 17.75	$ 21.48
Weighted average remaining contractual life of options outstanding (in years)	2 years 6 months 3 days
Number of stock options exercisable (in options) | shares	9,651,000	10,596,000
Weighted average exercise price of options exercisable (in cad per option)	$ 16.11	$ 19.27
Number of options outstanding (in options) | shares	18,883,000	18,498,000	19,967,000
Weighted average exercise price of stock options outstanding (in cad per option)	$ 12.01	$ 17.75	$ 21.48
Weighted average remaining contractual life of options outstanding (in years)	2 years 6 months 3 days
Number of stock options exercisable, end of year (in options) | shares	9,651,000	10,596,000
Weighted average exercise price of options exercisable (in cad per option)	$ 16.11	$ 19.27
$2.77 - $8.00
Disclosure of range of exercise prices of outstanding share options [line items]
Number of options outstanding (in options) | shares	5,650,000
Weighted average exercise price of stock options outstanding (in cad per option)	$ 2.85
Weighted average remaining contractual life of options outstanding (in years)	4 years 2 months 1 day
Number of stock options exercisable (in options) | shares	0
Weighted average exercise price of options exercisable (in cad per option)	$ 0
Number of options outstanding (in options) | shares	5,650,000
Weighted average exercise price of stock options outstanding (in cad per option)	$ 2.85
Weighted average remaining contractual life of options outstanding (in years)	4 years 2 months 1 day
Number of stock options exercisable, end of year (in options) | shares	0
Weighted average exercise price of options exercisable (in cad per option)	$ 0
$2.77 - $8.00 | Minimum
Disclosure of range of exercise prices of outstanding share options [line items]
Exercise price of options (in CAD per option)	2.77
Exercise price of options (in CAD per option)	2.77
$2.77 - $8.00 | Maximum
Disclosure of range of exercise prices of outstanding share options [line items]
Exercise price of options (in CAD per option)	8
Exercise price of options (in CAD per option)	$ 8
$15.93 - $21.87
Disclosure of range of exercise prices of outstanding share options [line items]
Number of options outstanding (in options) | shares	6,085,000
Weighted average exercise price of stock options outstanding (in cad per option)	$ 14.88
Weighted average remaining contractual life of options outstanding (in years)	1 year 11 months 1 day
Number of stock options exercisable (in options) | shares	3,802,000
Weighted average exercise price of options exercisable (in cad per option)	$ 15.22
Number of options outstanding (in options) | shares	6,085,000
Weighted average exercise price of stock options outstanding (in cad per option)	$ 14.88
Weighted average remaining contractual life of options outstanding (in years)	1 year 11 months 1 day
Number of stock options exercisable, end of year (in options) | shares	3,802,000
Weighted average exercise price of options exercisable (in cad per option)	$ 15.22
$15.93 - $21.87 | Minimum
Disclosure of range of exercise prices of outstanding share options [line items]
Exercise price of options (in CAD per option)	8.01
Exercise price of options (in CAD per option)	8.01
$15.93 - $21.87 | Maximum
Disclosure of range of exercise prices of outstanding share options [line items]
Exercise price of options (in CAD per option)	15.92
Exercise price of options (in CAD per option)	$ 15.92
Exercise Price Range Three
Disclosure of range of exercise prices of outstanding share options [line items]
Number of options outstanding (in options) | shares	7,148,000
Weighted average exercise price of stock options outstanding (in cad per option)	$ 16.80
Weighted average remaining contractual life of options outstanding (in years)	1 year 8 months 8 days
Number of stock options exercisable (in options) | shares	5,849,000
Weighted average exercise price of options exercisable (in cad per option)	$ 16.70
Number of options outstanding (in options) | shares	7,148,000
Weighted average exercise price of stock options outstanding (in cad per option)	$ 16.80
Weighted average remaining contractual life of options outstanding (in years)	1 year 8 months 8 days
Number of stock options exercisable, end of year (in options) | shares	5,849,000
Weighted average exercise price of options exercisable (in cad per option)	$ 16.70
Exercise Price Range Three | Minimum
Disclosure of range of exercise prices of outstanding share options [line items]
Exercise price of options (in CAD per option)	15.93
Exercise price of options (in CAD per option)	15.93
Exercise Price Range Three | Maximum
Disclosure of range of exercise prices of outstanding share options [line items]
Exercise price of options (in CAD per option)	21.87
Exercise price of options (in CAD per option)	$ 21.87

Share Capital - Fair Value (Det

Share Capital - Fair Value (Details)	12 Months Ended
	Dec. 31, 2020CAD ($)year$ / shares	Dec. 31, 2019CAD ($)year$ / shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Dividend per option	$ 0.21	$ 0.42
Expected life of share options from vesting date (years) | year	1.99	1.97
Expected forfeiture rate (percent)	8.60%	8.80%
Weighted average exercise price (in CAD per option) | $ / shares	$ 13.71	$ 18.19
Weighted average fair value (in CAD per option)	$ 0.87	$ 0.25
Minimum
Disclosure of terms and conditions of share-based payment arrangement [line items]
Range of expected volatilities used (percent)	47.20%	27.50%
Range of risk-free interest rates used (percent)	0.06%	1.66%
Maximum
Disclosure of terms and conditions of share-based payment arrangement [line items]
Range of expected volatilities used (percent)	90.20%	35.50%
Range of risk-free interest rates used (percent)	0.39%	1.74%

Share Capital - Performance Sha

Share Capital - Performance Share Units (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020CAD ($)sharesyear	Dec. 31, 2019CAD ($)sharesyear
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share option, term | year	1.99	1.97
Weighted average remaining contractual life of options outstanding (in years)	2 years 6 months 3 days
Performance Share Units (PSUs)
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share option, term | year	3
Liabilities from share-based payment transactions | $	$ 29	$ 34
Share-based compensation expense | $	7	4
Payment for performance share units which vested in the year | $	$ 12	$ 34
Performance Share Units, Beginning balance (in units)	14,318,642	11,606,644
Performance Share Units, Granted (in units)	10,828,280	7,673,960
Performance Share Units, Exercised (in units)	(2,111,552)	(2,429,816)
Performance Share Units, Forfeited (in units)	(3,735,485)	(2,532,146)
Performance Share Units, Ending balance (in units)	19,299,885	14,318,642
Performance Share Units, Vested (in units)	4,621,999	3,264,840

Share Capital - Earnings Per Sh

Share Capital - Earnings Per Share (Details) - CAD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Earnings per share [abstract]
Net loss	$ (10,016)	$ (1,370)
Effect of dividends declared on preferred shares in the year	(35)	(35)
Net loss – basic	(10,051)	(1,405)
Dilutive effect of accounting for stock options	4	(15)
Net loss – diluted	$ (10,047)	$ (1,420)
Weighted average number of common shares outstanding, basic	1,005.1	1,005.1
Weighted average common shares outstanding – diluted	1,005.1	1,005.1
Loss per share – basic ($/share)	$ (10)	$ (1.40)
Loss per share – diluted ($/share)	$ (10)	$ (1.41)
Stock Option Plan
Earnings per share [abstract]
Dilutive effect of share options on number of ordinary shares	13	18
Retained Earnings (deficit)
Earnings per share [abstract]
Net loss	$ (10,016)	$ (1,370)

Production, Operating and Tra_3

Production, Operating and Transportation and Selling, General, and Administrative Expenses - Production, Operating and Trasportation Expenses (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Analysis of income and expense [abstract]
Services and support costs	$ 1,119	$ 1,255
Salaries and benefits	576	773
Materials, equipment rentals and leases	191	250
Energy and utility	476	482
Licensing fees	160	204
Transportation	18	17
Other	20	49
Total production, operating and transportation expenses(1)	$ 2,560	$ 3,030

Production, Operating and Tra_4

Production, Operating and Transportation and Selling, General, and Administrative Expenses - Selling, general and administrative (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Analysis of income and expense [abstract]
Employee costs(1)	$ 443	$ 450
Stock-based compensation expense (recovery)(2)	16	(2)
Contract services	128	133
Equipment rentals and leases	16	11
Maintenance and other	142	101
Total selling, general and administrative expenses	$ 745	$ 693

Financial Items (Details)

Financial Items (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Foreign exchange gain
Non-cash working capital	$ 7	$ 17
Other foreign exchange	7	27
Net foreign exchange gains (losses)	14	44
Finance income	25	74
Finance expenses
Interest costs incurred	(355)	(422)
Capitalized interest (note 22)	60	177
Finance costs and interest before net foreign exchange gain (loss)	(295)	(245)
Accretion of asset retirement obligations (note 18)	(104)	(106)
Finance expenses	(399)	(351)
Financial items	$ (360)	$ (233)
Capitalisation rate of borrowing costs eligible for capitalisation	3.00%	5.00%
Interest costs incurred	$ 355	$ 422
Finance income	25	74
Long-term debt
Finance expenses
Interest costs incurred	(251)	(310)
Interest costs incurred	251	310
Other
Finance expenses
Interest costs incurred	(7)	(6)
Interest costs incurred	7	6
Lease liabilities [member]
Finance expenses
Interest costs incurred	(97)	(106)
Interest costs incurred	$ 97	$ 106

Pensions and Other Post-emplo_3

Pensions and Other Post-employment Benefits - Defined Contribution Pension Plan. Defined Benefit Obligation, Fair Value of Plan Assets and Funded Status (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of net defined benefit liability (asset) [line items]
Defined contribution plan expense	$ 56	$ 59
DB Pension Plans
Disclosure of net defined benefit liability (asset) [line items]
Current service cost	0	0
Interest cost	0	0
Past service cost	0	3
Remeasurements
Actuarial gain – experience	0	0
Actuarial loss – financial assumptions	4	9
Return on plan assets greater than discount rate	(3)	(16)
Past service cost	0	3
DB Pension Plans | Defined benefit obligation
Disclosure of net defined benefit liability (asset) [line items]
Defined benefit obligation, beginning balance	39	79
Current service cost	0	0
Interest cost	1	2
Benefits paid	(2)	(3)
Past service cost	0	3
Settlements	0	(49)
Remeasurements
Actuarial gain – experience	0	0
Actuarial loss – financial assumptions	4	9
Increase (decrease) through changes in foreign exchange rates, net defined benefit liability (asset)	(1)	(2)
Defined benefit obligation, ending balance	41	39
Past service cost	0	3
DB Pension Plans | Fair value of plan assets
Disclosure of net defined benefit liability (asset) [line items]
Defined benefit obligation, beginning balance	31	71
Interest cost	1	2
Contributions by employer	0	(1)
Benefits paid	(2)	(3)
Settlements	0	(52)
Remeasurements
Increase (decrease) through changes in foreign exchange rates, net defined benefit liability (asset)	(1)	(2)
Return on plan assets greater than discount rate	3	16
Defined benefit obligation, ending balance	32	31
OPEB Plans
Disclosure of net defined benefit liability (asset) [line items]
Current service cost	9	10
Interest cost	6	7
Past service cost	0	(29)
Remeasurements
Actuarial gain – experience	(1)	(1)
Actuarial loss – financial assumptions	14	20
Return on plan assets greater than discount rate	0	0
Past service cost	0	(29)
OPEB Plans | Defined benefit obligation
Disclosure of net defined benefit liability (asset) [line items]
Defined benefit obligation, beginning balance	201	199
Current service cost	9	10
Interest cost	6	7
Benefits paid	(5)	(4)
Past service cost	0	(29)
Settlements	0	0
Remeasurements
Actuarial gain – experience	(1)	(1)
Actuarial loss – financial assumptions	14	20
Increase (decrease) through changes in foreign exchange rates, net defined benefit liability (asset)	0	(1)
Defined benefit obligation, ending balance	224	201
Past service cost	0	(29)
OPEB Plans | Fair value of plan assets
Disclosure of net defined benefit liability (asset) [line items]
Defined benefit obligation, beginning balance	0	0
Interest cost	0	0
Contributions by employer	3	2
Benefits paid	(3)	(2)
Settlements	0	0
Remeasurements
Increase (decrease) through changes in foreign exchange rates, net defined benefit liability (asset)	0	0
Return on plan assets greater than discount rate	0	0
Defined benefit obligation, ending balance	0	0
Retirement Plan Funding Status [Member] | DB Pension Plans
Disclosure of net defined benefit liability (asset) [line items]
Defined benefit obligation, beginning balance	(8)
Remeasurements
Defined benefit obligation, ending balance	(9)	(8)
Retirement Plan Funding Status [Member] | OPEB Plans
Disclosure of net defined benefit liability (asset) [line items]
Defined benefit obligation, beginning balance	(201)
Remeasurements
Defined benefit obligation, ending balance	$ (224)	$ (201)

Pensions and Other Post-emplo_4

Pensions and Other Post-employment Benefits - Narrative (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2022
Disclosure of defined benefit plans [line items]
Remeasurement of pension plans	$ 2,000,000	$ (1,000,000)
DB Pension Plans
Disclosure of defined benefit plans [line items]
Actuarial gains (losses) arising from remeasurement of plan assets	0	0
Past service cost and gains (losses) arising from settlements, net defined benefit liability (asset)		5
Tax on Past service cost and gains (losses) arising from settlements, net defined benefit liability (asset)	1
OPEB Plans
Disclosure of defined benefit plans [line items]
Actuarial gains (losses) arising from remeasurement of plan assets	(1,000,000)	(1,000,000)
Fair value of plan assets | DB Pension Plans
Disclosure of defined benefit plans [line items]
Contributions by employer	0	(1,000,000)
Fair value of plan assets | OPEB Plans
Disclosure of defined benefit plans [line items]
Contributions by employer	3,000,000	2,000,000
Defined benefit obligation | DB Pension Plans
Disclosure of defined benefit plans [line items]
Actuarial gains (losses) arising from remeasurement of plan assets	0	0
Defined benefit obligation | OPEB Plans
Disclosure of defined benefit plans [line items]
Actuarial gains (losses) arising from remeasurement of plan assets	$ (1,000,000)	$ (1,000,000)
Canada | Fair value of plan assets | OPEB Plans
Disclosure of defined benefit plans [line items]
Actuarial assumption of medical cost trend rates	6.00%		5.00%
Actuarial assumption of medical cost trend rates, decreases per period	0.50%
Canada | Defined benefit obligation | OPEB Plans
Disclosure of defined benefit plans [line items]
Actuarial assumption of medical cost trend rates	6.00%
Actuarial assumption of medical cost trend rates, decreases per period	0.50%
United States | Fair value of plan assets | OPEB Plans
Disclosure of defined benefit plans [line items]
Actuarial assumption of medical cost trend rates	6.50%		5.00%
Actuarial assumption of medical cost trend rates, decreases per period	0.25%
United States | Defined benefit obligation | OPEB Plans
Disclosure of defined benefit plans [line items]
Actuarial assumption of medical cost trend rates	6.50%
Actuarial assumption of medical cost trend rates, decreases per period	0.25%
Actuarial assumption of average health care cost trend for 2022 and thereafter | Canada | OPEB Plans
Disclosure of defined benefit plans [line items]
Actuarial assumption of medical cost trend rates			5.00%
Actuarial assumption of average health care cost trend for 2022 and thereafter | United States | OPEB Plans
Disclosure of defined benefit plans [line items]
Actuarial assumption of medical cost trend rates			5.00%

Pensions and Other Post-emplo_5

Pensions and Other Post-employment Benefits - DB Pension Plan Assets (Details)	Dec. 31, 2020	Dec. 31, 2019
Disclosure of employee benefits [Abstract]
Target allocation, Money market type funds (percent)	0.00%
Target allocation, Equity securities (percent)	3500.00%
Target allocation, Debt securities (percent)	65.00%
Money market type funds (percent)	0.00%	0.00%
Equity securities (percent)	35.00%	35.00%
Debt securities (percent)	65.00%	65.00%

Pensions and Other Post-emplo_6

Pensions and Other Post-employment Benefits - Defined Contribution Pension Plan - Net Earnings and OCI (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
DB Pension Plans
Disclosure of defined benefit plans [line items]
Current service cost	$ 0	$ 0
Past service cost	0	3
Interest cost	0	0
Benefit cost	0	3
Actuarial gain – experience	0	0
Actuarial loss – financial assumptions	4	9
Return on plan assets greater than discount rate	(3)	(16)
Remeasurement effects recognized in OCI	1	(7)
OPEB Plans
Disclosure of defined benefit plans [line items]
Current service cost	9	10
Past service cost	0	(29)
Interest cost	6	7
Benefit cost	15	(12)
Actuarial gain – experience	(1)	(1)
Actuarial loss – financial assumptions	14	20
Return on plan assets greater than discount rate	0	0
Remeasurement effects recognized in OCI	$ 13	$ 19

Pensions and Other Post-emplo_7

Pensions and Other Post-employment Benefits - Actuarial Assumptions and Sensitivity Analysis (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
DB Pension Plans
Disclosure of defined benefit plans [line items]
Rate of compensation expense	3.50%	3.50%
Rate of compensation expense	3.50%	3.50%
Minimum | DB Pension Plans
Disclosure of defined benefit plans [line items]
Discount rate for benefit expense and obligation	0.80%	2.30%
Minimum | OPEB Plans
Disclosure of defined benefit plans [line items]
Discount rate for benefit expense and obligation	2.50%	3.00%
Maximum | DB Pension Plans
Disclosure of defined benefit plans [line items]
Discount rate for benefit expense and obligation	3.20%	4.20%
Maximum | OPEB Plans
Disclosure of defined benefit plans [line items]
Discount rate for benefit expense and obligation	3.20%	3.70%
Discount rate | DB Pension Plans
Disclosure of defined benefit plans [line items]
Impact on defined benefit obligation, increase in assumption	$ (5)
Impact on defined benefit obligation, decrease in assumption	6
Discount rate | OPEB Plans
Disclosure of defined benefit plans [line items]
Impact on defined benefit obligation, increase in assumption	(25)
Impact on defined benefit obligation, decrease in assumption	31
Health care cost trend rate | OPEB Plans
Disclosure of defined benefit plans [line items]
Impact on defined benefit obligation, increase in assumption	25
Impact on defined benefit obligation, decrease in assumption	$ (22)

Cash Flows - Change in Non-ca_3

Cash Flows - Change in Non-cash Working Capital (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of cash flow statement [Abstract]
Accounts receivable	$ 724	$ (176)
Inventories	377	(502)
Prepaid expenses	(14)	(30)
Accounts payable and accrued liabilities	(1,152)	604
Change in non-cash working capital	(65)	(104)
Change in non-cash working capital, operating activities	347	(280)
Change in non-cash working capital, financing activities	11	3
Change in non-cash working capital, investing activities	$ (423)	$ 173

Financial Instruments and Ris_3

Financial Instruments and Risk Management - Financial Instruments at Fair Value (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Financial Assets And Liabilities [Line Items]
Derivative financial liabilities	$ (27,000,000)	$ (39,000,000)
Trading inventories measured at fair value less costs to sell	121,000,000	155,000,000
Derivatives | FVTPL
Disclosure Of Financial Assets And Liabilities [Line Items]
Net unsettled premiums	12
Derivatives | Natural gas(1) | FVTPL
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, at fair value	33,000,000	31,000,000
Derivatives | Natural gas(1) | FVTPL, held-for-trading
Disclosure Of Financial Assets And Liabilities [Line Items]
Increase (decrease) in financial assets	25,000,000	(4,000,000)
Trading inventories measured at fair value less costs to sell	37,000,000	19,000,000
Derivatives | Crude oil(2) | FVTPL
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, at fair value	8,000,000	11,000,000
Derivatives | Crude oil(2) | FVTPL, held-for-trading
Disclosure Of Financial Assets And Liabilities [Line Items]
Increase (decrease) in financial assets	5,000,000	12,000,000
Trading inventories measured at fair value less costs to sell	84,000,000	136,000,000
Derivatives | Foreign currency forwards | FVTPL
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, at fair value	0	2,000,000
Derivatives | Crude oil call options | FVTPL
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, at fair value	(23,000,000)	(2,000,000)
Derivatives | Crude oil put options | FVTPL
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, at fair value	8,000,000	(4,000,000)
Other financial assets | FVTPL
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial assets, at fair value	1,000,000	1,000,000
Financial liabilities at amortised cost
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial liabilities	6,100,000,000	5,000,000,000
Financial liabilities, at fair value	$ 6,600,000,000	$ 5,300,000,000

Financial Instruments and Ris_4

Financial Instruments and Risk Management - Market Risk (Details)	12 Months Ended
	Dec. 31, 2020CAD ($)	Dec. 31, 2019CAD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Disclosure Of Financial Assets And Liabilities [Line Items]
Unrealized mark to market loss (note 25)	$ 10,000,000	$ 44,000,000
Line of credit, maximum borrowing capacity	4,975,000,000
Long-term debt	6,117,000,000	4,570,000,000	$ 2,387,000,000	$ 2,387,000,000
Tax relating to cash flow hedges	(3,000,000)	(3,000,000)
Adjustments for fair value losses (gains), net of put and call options	(1,000,000)	38
Volume hedging selling call options	82,337
Volume hedging buying put options	95,380
Volume hedging selling put options	6,522
Average call option sold price	48.11
Average Purchased Put Price	41.25
Average Sold Put Price	37
Unrealized Gain (Loss) On Hedging Instrument, Fair Value Hedges	9	6,000,000
Authorized Capital Commitments, Pre-Registration	1.75		3
Realized Gain (Loss) On Hedging Instrument, Fair Value Hedges	88	16,000,000
Hedges of net investment in foreign operations [member]
Disclosure Of Financial Assets And Liabilities [Line Items]
Financial instruments designated as hedging instruments, at fair value			$ 2,400,000,000	$ 2,400,000,000
Gains (losses) on hedges of net investments in foreign operations, net of tax	44,000,000	146,000,000
Income tax relating to components of other comprehensive income that will not be reclassified to profit or loss	6,000,000	$ 30,000,000
Syndicated Bank Facilities [Member]
Disclosure Of Financial Assets And Liabilities [Line Items]
Line of credit, maximum borrowing capacity	$ 4,000,000,000

Financial Instruments and Ris_5

Financial Instruments and Risk Management - Offsetting Financial Assets and Liabilities (Details) - CAD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Offsetting financial assets [abstract]
Offsetting financial assets, Gross amount	$ 460	$ 896
Offsetting financial assets, Amount offset	362	(300)
Offsetting financial assets, Net amount	98	596
Offsetting financial liabilities [abstract]
Offsetting financial liabilities, Gross amount	656	(891)
Offsetting financial liabilities, Amount offset	394	306
Offsetting financial liabilities, Net amount	262	(585)
Financial liabilities, derivatives
Offsetting financial liabilities [abstract]
Offsetting financial liabilities, Gross amount	116	(48)
Offsetting financial liabilities, Amount offset	87	25
Offsetting financial liabilities, Net amount	29	(23)
Financial liabilities, normal purchase and sale agreements
Offsetting financial liabilities [abstract]
Offsetting financial liabilities, Gross amount	540	(843)
Offsetting financial liabilities, Amount offset	307	281
Offsetting financial liabilities, Net amount	233	(562)
Financial assets, derivatives
Offsetting financial assets [abstract]
Offsetting financial assets, Gross amount	69	79
Offsetting financial assets, Amount offset	51	(26)
Offsetting financial assets, Net amount	18	53
Financial assets, normal purchase and sale agreements
Offsetting financial assets [abstract]
Offsetting financial assets, Gross amount	391	817
Offsetting financial assets, Amount offset	311	(274)
Offsetting financial assets, Net amount	$ 80	$ 543

Financial Instruments and Ris_6

Financial Instruments and Risk Management - Market Risk Sensitivity Analysis (Details) - Commodity price risk $ in Millions	12 Months Ended
	Dec. 31, 2020CAD ($)
Sensitivity analysis, increase | Crude oil price
Disclosure of nature and extent of risks arising from financial instruments [line items]
Market risk sensitivity analysis	$ (8)
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, percent	10.00%
Sensitivity analysis, increase | Natural gas price
Disclosure of nature and extent of risks arising from financial instruments [line items]
Market risk sensitivity analysis	$ (2)
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, percent	10.00%
Sensitivity analysis, decrease | Crude oil price
Disclosure of nature and extent of risks arising from financial instruments [line items]
Market risk sensitivity analysis	$ 8
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, percent	10.00%
Sensitivity analysis, decrease | Natural gas price
Disclosure of nature and extent of risks arising from financial instruments [line items]
Market risk sensitivity analysis	$ 2
Sensitivity analysis for types of market risk, reasonably possible change in risk variable, percent	10.00%

Financial Instruments and Ris_7

Financial Instruments and Risk Management - Financial Risk (Details)	12 Months Ended
	Dec. 31, 2020CAD ($)	Dec. 31, 2019CAD ($)	Dec. 31, 2020USD ($)
Disclosure of detailed information about financial instruments [line items]
Line of credit, maximum borrowing capacity	$ 4,975,000,000
Line of credit, current borrowing capacity	4,158,000,000
Authorized Capital Commitments, Pre-Registration	1.75		$ 3
Revenues	13,301,000,000	$ 19,902,000,000
Bank operating loan
Disclosure of detailed information about financial instruments [line items]
Line of credit, maximum borrowing capacity	975,000,000	900,000,000
Line of credit, current borrowing capacity	508,000,000
Syndicated Bank Facilities [Member]
Disclosure of detailed information about financial instruments [line items]
Line of credit, maximum borrowing capacity	4,000,000,000
Line of credit, current borrowing capacity	3,650,000,000
Customer concentration risk [Member]
Disclosure of detailed information about financial instruments [line items]
Revenues		$ 3,900,000,000
Single customer over 10% of revenue | Customer concentration risk [Member]
Disclosure of detailed information about financial instruments [line items]
Revenues	$ 2,300,000,000

Financial Instruments and Ris_8

Financial Instruments and Risk Management - Accounts Receivable Aging (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of financial assets that are either past due or impaired [line items]
Impairment loss, receivables	$ 1	$ 4
Trade receivables
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivable	1,119
Trade receivables | Provision for expected credit losses
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivable	(36)
Trade receivables | Current | Cost
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivable	1,076
Trade receivables | Past due (1 – 30 days) | Cost
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivable	63
Trade receivables | Past due (31 – 60 days) | Cost
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivable	4
Trade receivables | Past due (61 – 90 days) | Cost
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivable	3
Trade receivables | Past due (more than 90 days) | Cost
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivable	$ 9

Government grants (Details)

Government grants (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020CAD ($)
Government Grants [Abstract]
Income from government grants	$ 82

Related Party Transactions - Si

Related Party Transactions - Significant Subsidiaries and Joint Operations (Details) - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Sunrise Oil Sands Partnership
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint operation	50.00%
BP-Husky Refining LLC
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint operation	50.00%
Entities with joint control or significant influence over entity | Husky Oil Operations Limited
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint operation	100.00%
Entities with joint control or significant influence over entity | Husky Energy International Corporation
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint operation	100.00%
Entities with joint control or significant influence over entity | Lima Refining Company
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint operation	100.00%
Entities with joint control or significant influence over entity | Husky Marketing and Supply Company
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint operation	100.00%
Entities with joint control or significant influence over entity | Husky Oil Limited Partnership
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint operation	100.00%
Entities with joint control or significant influence over entity | Husky Canadian Petroleum Marketing Partnership
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint operation	100.00%
Entities with joint control or significant influence over entity | Husky Energy Marketing Partnership
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint operation	100.00%
Entities with joint control or significant influence over entity | Sunrise Oil Sands Partnership
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint operation	50.00%
Entities with joint control or significant influence over entity | BP-Husky Refining LLC
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint operation	50.00%
Husky Midstream Limited Partnership | Joint ventures where entity is venturer
Disclosure of transactions between related parties [line items]
Revenue from rendering of services, related party transactions	$ 250,000,000	$ 424,000,000
Purchases of goods, related party transactions	239,000,000
Distributions, Related Party Transactions	144,000,000	94,000,000
Contributions, Related Party Transactions	83,000,000	37,000,000
Due from related parties, related party transactions	$ 23,000,000	$ 143

Related Party Transactions (Det

Related Party Transactions (Details) - Husky Midstream Limited Partnership - CAD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of transactions between related parties [line items]
Share of equity investment	35.00%	35.00%
Joint ventures where entity is venturer
Disclosure of transactions between related parties [line items]
Revenue from rendering of services, related party transactions	$ 250,000,000	$ 424,000,000
Purchases of goods, related party transactions	239,000,000
Distributions, Related Party Transactions	144,000,000	94,000,000
Contributions, Related Party Transactions	83,000,000	37,000,000
Due from related parties, related party transactions	23,000,000	143
Deferred Revenue From Construction Contracts, Percentage of Completion Method	10,000,000	0
Current payables to related parties	$ 20,000,000	$ 16,000,000

Related Party Transactions - Co

Related Party Transactions - Compensation of key management personnel (Details) - Key management personnel - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of transactions between related parties [line items]
Short-term employee benefits(1)	$ 15	$ 18
Stock-based compensation(2)	15	26
Key management personnel compensation	$ 30	$ 44

Commitments and Contingencies_2

Commitments and Contingencies (Details) - CAD ($)	Dec. 31, 2020	Dec. 31, 2019
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Firm transportation agreements(1)(4)	$ 7,421,000,000
Unconditional purchase obligations(2)	8,417,000,000
Lease rentals and exploration work agreements	1,156,000,000
Obligations to fund equity investee(3)	653,000,000
Minimum future payments for commitments	18,650,000,000
Operating agreements(1)	1,003,000,000
Firm transportation agreements(1)(4)	7,421,000,000
Within 1 year
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Firm transportation agreements(1)(4)	552,000,000
Unconditional purchase obligations(2)	1,766,000,000
Lease rentals and exploration work agreements	74,000,000
Obligations to fund equity investee(3)	54,000,000
Minimum future payments for commitments	2,543,000,000
Operating agreements(1)	97,000,000
Firm transportation agreements(1)(4)	552,000,000
After 1 year but no more than 5 years
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Firm transportation agreements(1)(4)	2,396,000,000
Unconditional purchase obligations(2)	3,327,000,000
Lease rentals and exploration work agreements	244,000,000
Obligations to fund equity investee(3)	319,000,000
Minimum future payments for commitments	6,667,000,000
Operating agreements(1)	381,000,000
Firm transportation agreements(1)(4)	2,396,000,000
More than 5 years
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Firm transportation agreements(1)(4)	4,473,000,000
Unconditional purchase obligations(2)	3,324,000,000
Lease rentals and exploration work agreements	838,000,000
Obligations to fund equity investee(3)	280,000,000
Minimum future payments for commitments	9,440,000,000
Operating agreements(1)	525,000,000
Firm transportation agreements(1)(4)	4,473,000,000
Husky Midstream Limited Partnership
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Firm transportation agreements(1)(4)	1.7
Operating agreements(1)	1.2
Firm transportation agreements(1)(4)	1.7
Subject to regulatory approval or not yet in service [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Firm transportation agreements(1)(4)	1.7	$ 1.6
Firm transportation agreements(1)(4)	$ 1.7	$ 1.6

Capital Disclosures (Details)

Capital Disclosures (Details) $ in Billions	12 Months Ended
	Dec. 31, 2020CAD ($)	Dec. 31, 2019CAD ($)
Disclosure of additional information [Abstract]
Equity and debt	$ 13.2	$ 22.8
Debt to capital ratio	0.466	0.242
Debt to capital ratio, target	0.65
Debt to funds from operation ratio	12.5	1.7
Debt to funds from operation ratio, target	2
Common [Table]
Debt To Capital Ratio, Temporarily Increased Covenant	0.75

Subsequent Events (Details)

Subsequent Events (Details) - CAD ($)	Jan. 04, 2021	Dec. 31, 2020
Common [Table]
Share Conversation Ratio Upon Merger - Common Shares		0.7845
Share Conversation Ratio Upon Merger - Preferred Shares		0.0651
Performance Share Unit Payment Upon Completion of Strategic Combination	$ 122

Uncategorized Items - huskf-202

Label	Element	Value
Allowance account for credit losses of financial assets	ifrs-full_AllowanceAccountForCreditLossesOfFinancialAssets	$ 36,000,000
Allowance account for credit losses of financial assets	ifrs-full_AllowanceAccountForCreditLossesOfFinancialAssets	34,000,000
Current derivative financial assets	ifrs-full_CurrentDerivativeFinancialAssets	33,000,000
Current derivative financial assets	ifrs-full_CurrentDerivativeFinancialAssets	38,000,000
Current trade receivables	ifrs-full_CurrentTradeReceivables	773,000,000
Current trade receivables	ifrs-full_CurrentTradeReceivables	1,327,000,000
Other current receivables	ifrs-full_OtherCurrentReceivables	349,000,000
Other current receivables	ifrs-full_OtherCurrentReceivables	$ 168,000,000
Husky Midstream Limited Partnership [Member]
Disclosure of joint ventures [text block]	ifrs-full_DisclosureOfJointVenturesExplanatory	Summarized below is the financial information for HMLP accounted for using the equity method: Results of Operations ($ millions, except share of equity investment) 2020 2019 Revenues 322 316 Expenses (206) (228) Net earnings 116 88 Share of equity investment 35 % 35 % Proportionate share of equity investment (1) (32) 9 (1) As at December 31, 2020, the Company’s share of pre-tax losses relating to its investment in HMLP were $7 million (2019 – $nil) which were unrecognized as a result of the investment being fully written off in the third quarter of 2020. Balance Sheet ($ millions, except share of net assets) December 31, 2020 December 31, 2019 Current assets (1) 108 171 Non-current assets 3,075 3,031 Current liabilities (30) (163) Non-current liabilities (1,175) (1,059) Net assets 1,978 1,980 Share of net assets 35 % 35 % Carrying amount in balance sheet — 666 (1) Current assets include cash and cash equivalents of $30 million (2019 – $86 million).
Non-controlling interests [member]
Dividends paid to non-controlling interests	ifrs-full_DividendsPaidToNoncontrollingInterests	$ 2,000,000
Equity attributable to owners of parent [member]
Dividends paid to non-controlling interests	ifrs-full_DividendsPaidToNoncontrollingInterests	$ 2,000,000
Redeemable Preferred Shares, Series 5 Preferred Shares [Member] | Five Year Government of Canada Bond Yield
Dividend rate	huskf_DividendRate	4.591
Redeemable Preferred Shares, Series 7 Preferred Shares [Member] | Five Year Government of Canada Bond Yield
Dividend rate	huskf_DividendRate	3.935
Undeveloped Land [Member]
Land	ifrs-full_Land	$ 118,000,000
Land	ifrs-full_Land	$ 127,000,000