v3.20.1
Investment in Cenovus Energy - Textual (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
3 Months Ended 5 Months Ended
Mar. 31, 2020
Mar. 31, 2019
May 17, 2017
Dec. 31, 2019
Entity [Domain]        
Schedule Of Available For Sale Securities [Line Items]        
Unrealized (gain) loss on investment in Cenovus Energy $ 1,691 $ (343)    
Foster Creek Christina Lake (FCCL) [Member] | Entity [Domain]        
Schedule Of Available For Sale Securities [Line Items]        
Equity Method Investment, Ownership Percentage     50.00%  
Cenovus Energy Common Stock [Member] | Entity [Domain]        
Schedule Of Available For Sale Securities [Line Items]        
Shares Exchange for Assets Held for Sale 208   208  
Investment Owned, Common Stock, percent of Issued and Outstanding     16.90%  
Investment In Equity Security Fair Value $ 420   $ 1,960 $ 2,110
Cenovus Energy Common Stock [Member] | Cenovus Energy Inc. [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Cenovus Energy common share price $ 2.02   $ 9.41  
Unrealized (gain) loss on investment in Cenovus Energy $ 1,690