v3.20.2
Investment in Cenovus Energy - Textual (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Dec. 31, 2019
May 17, 2017
Schedule Of Available For Sale Securities [Line Items]            
Investment in Cenovus Energy $ 809   $ 809   $ 2,111  
Unrealized (gain) loss on investment in Cenovus Energy     $ 1,302 $ (489)    
Foster Creek Christina Lake (FCCL) [Member]            
Schedule Of Available For Sale Securities [Line Items]            
Equity Method Investment, Ownership Percentage           50.00%
Cenovus Energy Common Stock [Member]            
Schedule Of Available For Sale Securities [Line Items]            
Shares Exchange for Assets Held for Sale 208   208     208
Investment Owned, Common Stock, percent of Issued and Outstanding           16.90%
Investment in Cenovus Energy $ 809   $ 809   $ 2,110 $ 1,960
Unrealized (gain) loss on investment in Cenovus Energy $ 162 $ (116) $ 1,300 $ (489)    
Cenovus Energy Common Stock [Member] | Cenovus Energy Inc [Member]            
Schedule Of Available For Sale Securities [Line Items]            
Cenovus Energy common share price $ 3.89   $ 3.89     $ 9.41