Business Segments (Detail) - CAD
CAD in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Dec. 31, 2015
Revenues and other income          
Operating revenues [1],[2] CAD 6,568 [3] CAD 7,111 [3] CAD 17,967 [4] CAD 20,553 [4]  
Investment and other income 874 44 945 106  
Total revenues and other income 7,442 7,155 18,912 20,659  
Expenses          
Exploration 16 19 75 52  
Purchases of crude oil and products [5] 3,857 4,053 10,884 11,653  
Production and manufacturing [6] 1,261 1,351 3,842 4,105  
Selling and general [6] 275 267 812 803  
Federal excise tax [2] 434 416 [7] 1,237 [7] 1,180  
Depreciation and depletion 398 400 1,229 1,052  
Financing costs (note 5) 19 12 52 20  
Total expenses 6,260 6,518 18,131 18,865  
Income (loss) before income taxes 1,182 637 781 1,794  
Income taxes 179 158 60 774  
Net income (loss) 1,003 479 721 1,020  
Cash flows from (used in) operating activities 772 1,104 1,264 1,762  
Capital and exploration expenditures [8] 205 1,142 948 3,011  
Total assets 42,094 43,452 42,094 43,452 CAD 43,170
Upstream          
Revenues and other income          
Operating revenues 1,316 [3] 1,467 [3] 3,699 [4] 4,462 [4]  
Intersegment sales 709 610 1,516 1,926  
Investment and other income 1 4 22 22  
TOTAL OPERATING REVENUES, INTERSEGMENT SALES, INVESTMENT AND OTHER INCOME 2,026 2,081 5,237 6,410  
Expenses          
Exploration 16 19 75 52  
Purchases of crude oil and products 861 879 2,584 2,787  
Production and manufacturing 887 923 2,634 2,826  
Selling and general (1) 1 (3)    
Depreciation and depletion 346 333 1,053 865  
Financing costs (note 5) (2) 2 (6) 5  
Total expenses 2,107 2,157 6,337 6,535  
Income (loss) before income taxes (81) (76) (1,100) (125)  
Income taxes (55) (24) (336) 290  
Net income (loss) (26) (52) (764) (415)  
Cash flows from (used in) operating activities 432 696 32 181  
Capital and exploration expenditures [8] 149 1,050 745 2,644  
Total assets 36,975 36,817 36,975 36,817  
Downstream          
Revenues and other income          
Operating revenues 4,971 [3] 5,344 [3] 13,470 [4] 15,191 [4]  
Intersegment sales 253 239 689 763  
Investment and other income 870 40 919 83  
TOTAL OPERATING REVENUES, INTERSEGMENT SALES, INVESTMENT AND OTHER INCOME 6,094 5,623 15,078 16,037  
Expenses          
Purchases of crude oil and products 3,827 3,906 10,139 11,172  
Production and manufacturing 323 377 1,059 1,125  
Selling and general 238 256 729 720  
Federal excise tax 434 416 1,237 1,180  
Depreciation and depletion 46 61 158 169  
Total expenses 4,868 5,016 13,322 14,366  
Income (loss) before income taxes 1,226 607 1,756 1,671  
Income taxes 224 153 363 437  
Net income (loss) 1,002 454 1,393 1,234  
Cash flows from (used in) operating activities 264 313 1,028 1,368  
Capital and exploration expenditures [8] 38 55 145 276  
Total assets 4,403 5,645 4,403 5,645  
Chemical          
Revenues and other income          
Operating revenues 281 [3] 300 [3] 798 [4] 900 [4]  
Intersegment sales 58 60 156 182  
Investment and other income 1   1    
TOTAL OPERATING REVENUES, INTERSEGMENT SALES, INVESTMENT AND OTHER INCOME 340 360 955 1,082  
Expenses          
Purchases of crude oil and products 188 176 518 563  
Production and manufacturing 51 51 149 154  
Selling and general 22 23 63 65  
Depreciation and depletion 2 3 6 8  
Total expenses 263 253 736 790  
Income (loss) before income taxes 77 107 219 292  
Income taxes 21 29 59 79  
Net income (loss) 56 78 160 213  
Cash flows from (used in) operating activities 73 109 205 269  
Capital and exploration expenditures [8] 7 17 21 33  
Total assets 379 386 379 386  
Corporate and Other          
Revenues and other income          
Investment and other income 2   3 1  
TOTAL OPERATING REVENUES, INTERSEGMENT SALES, INVESTMENT AND OTHER INCOME 2   3 1  
Expenses          
Selling and general 17 (12) 27 20  
Depreciation and depletion 4 3 12 10  
Financing costs (note 5) 21 10 58 15  
Total expenses 42 1 97 45  
Income (loss) before income taxes (40) (1) (94) (44)  
Income taxes (11)   (26) (32)  
Net income (loss) (29) (1) (68) (12)  
Cash flows from (used in) operating activities 3 (14) (1) (56)  
Capital and exploration expenditures [8] 11 20 37 58  
Total assets 674 777 674 777  
Consolidation, Eliminations          
Revenues and other income          
Intersegment sales (1,020) (909) (2,361) (2,871)  
TOTAL OPERATING REVENUES, INTERSEGMENT SALES, INVESTMENT AND OTHER INCOME (1,020) (909) (2,361) (2,871)  
Expenses          
Purchases of crude oil and products (1,019) (908) (2,357) (2,869)  
Selling and general (1) (1) (4) (2)  
Total expenses (1,020) (909) (2,361) (2,871)  
Total assets CAD (337) CAD (173) CAD (337) CAD (173)  
[1] Amounts from related parties included in operating revenues.*
[2] Federal excise tax included in operating revenues.
[3] Included export sales to the United States of $941 million (2015 - $1,168 million). Export sales to the United States were recorded in all operating segments, with the largest effects in the Upstream segment.
[4] Included export sales to the United States of $2,704 million (2015 - $3,331 million). Export sales to the United States were recorded in all operating segments, with the largest effects in the Upstream segment.
[5] Amounts to related parties included in purchases of crude oil and products.*
[6] Amounts to related parties included in production and manufacturing, and selling and general expenses.
[7] Note: Restated 2015.
[8] Capital and exploration expenditures (CAPEX) include exploration expenses, additions to property, plant and equipment, additions to capital leases, additional investments and acquisitions.