v3.7.0.1
Assets Held for Sale or Sold (Details)
shares in Millions, CAD in Millions, $ in Millions
3 Months Ended
Apr. 12, 2017
USD ($)
$ / MMBTU
Mar. 31, 2017
USD ($)
Mar. 29, 2017
CAD
CAD / bbl
shares
Mar. 29, 2017
USD ($)
CAD / bbl
shares
Mar. 31, 2016
USD ($)
Long Lived Assets Held For Sale [Line Items]          
Payments for (Proceeds from) Other Investing Activities   $ (129)     $ (4)
Income (Loss) from Equity Method Investments   200     (149)
Foster Creek Christina Lake (FCCL) and western Canada gas properties [Member]          
Long Lived Assets Held For Sale [Line Items]          
Payments for (Proceeds from) Other Investing Activities       $ 130  
Foster Creek Christina Lake (FCCL) and western Canada gas properties [Member] | Oil and Gas Properties [Member] | Disposal Group Held for sale Not Discontinued Operations [Member]          
Long Lived Assets Held For Sale [Line Items]          
Total Consideration Estimate       13,300  
Proceeds from asset dispositions       $ 10,600  
Shares Exchange for Assets Held for Sale | shares     208 208  
Payments for (Proceeds from) Other Investing Activities       $ 130  
Foster Creek Christina Lake (FCCL) and western Canada gas properties [Member] | Oil and Gas Properties [Member] | Disposal Group Held for sale Not Discontinued Operations [Member] | Contingent Payment, Maximum [Member]          
Long Lived Assets Held For Sale [Line Items]          
Assets Held for Sale, Contigent Consinderation, Contingent Payment Based on Crude Oil Price per Barrel Trigger | CAD     CAD 6    
Assets Held for Sale, Contingent Consideration Term     5 years 5 years  
Assets Held for Sale, Contigent Consideration, Crude Oil Price per Barrel Trigger | CAD / bbl     52 52  
Foster Creek Christina Lake (FCCL) [Member]          
Long Lived Assets Held For Sale [Line Items]          
Investment Owned Percent Of Net Assets       50.00%  
Foster Creek Christina Lake (FCCL) [Member] | Oil and Gas Properties [Member] | Disposal Group Held for sale Not Discontinued Operations [Member]          
Long Lived Assets Held For Sale [Line Items]          
Equity Method Investments   9,000      
Income (Loss) from Equity Method Investments   120     (154)
Western Canada Gas Properties [Member] | Oil and Gas Properties [Member] | Disposal Group Held for sale Not Discontinued Operations [Member]          
Long Lived Assets Held For Sale [Line Items]          
Assets Held for Sale, Property, Plant and Equipment Reclassification to Prepaid Expenses and Other Current Assets   2,400      
Assets Held for Sale, Property, Plant and Equipment Reclassification toNoncurrent Liabilities   671      
Profit before taxes   (61)     $ (145)
San Juan Basin [Member] | Disposal Group Held for sale Not Discontinued Operations [Member] | Scenario, Plan [Member] | Contingent Payment, Maximum [Member]          
Long Lived Assets Held For Sale [Line Items]          
Assets Held for Sale, Contingent Consideration Term 6 years        
Assets Held for Sale, Contingent Consideration, Effective Date Jan. 01, 2018        
Assets Held for Sale, Contingent Consideration, Henry Hub Price per Unit | $ / MMBTU 3.2        
San Juan Basin [Member] | Oil and Gas Properties [Member] | Disposal Group Held for sale Not Discontinued Operations [Member]          
Long Lived Assets Held For Sale [Line Items]          
Net carrying value   5,800      
Amount of PP&E in carrying value of assets   6,200      
Asset Retirement Obligation of held for sale or sold   $ 392      
San Juan Basin [Member] | Oil and Gas Properties [Member] | Disposal Group Held for sale Not Discontinued Operations [Member] | Scenario, Plan [Member]          
Long Lived Assets Held For Sale [Line Items]          
Total Consideration Estimate $ 3,000        
Proceeds from asset dispositions 2,700        
San Juan Basin [Member] | Oil and Gas Properties [Member] | Disposal Group Held for sale Not Discontinued Operations [Member] | Scenario, Plan [Member] | Contingent Payment, Maximum [Member]          
Long Lived Assets Held For Sale [Line Items]          
Proceeds from asset dispositions $ 300