v3.20.2
Investment in Cenovus Energy - Textual (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2020
Jun. 30, 2019
Jun. 30, 2020
Jun. 30, 2019
Dec. 31, 2019
May 17, 2017
Schedule Of Available For Sale Securities [Line Items]            
Investment in Cenovus Energy $ 971   $ 971   $ 2,111  
Unrealized (gain) loss on investment in Cenovus Energy     $ 1,140 $ (373)    
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 $ 971   $ 971   $ 2,110 $ 1,960
Unrealized (gain) loss on investment in Cenovus Energy $ (551) $ (30) $ 1,140 $ (373)    
Cenovus Energy Common Stock [Member] | Cenovus Energy Inc [Member]            
Schedule Of Available For Sale Securities [Line Items]            
Cenovus Energy common share price $ 4.67   $ 4.67     $ 9.41