v3.19.3.a.u2
Employee Benefit Plans - Stock option activity (Details) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Summary of Stock Options Activity      
Weighted-Average Exercise Price at the beginning of year $ 52.88    
Weighted-Average Exercise Price, exercised 36.28    
Weighted-Average Exercise Price at the end of year 54.11 $ 52.88  
Weighted-Average Exercise Price, Vested 54.14    
Weighted-Average Exercise Price, Exercisable $ 54.33    
Aggregate Intrinsic Value, outstanding at the beginning of the year $ 214,000,000    
Aggregate Intrinsic Value, exercised 39,000,000    
Aggregate Intrinsic Value, outstanding at the end of the year 206,000,000 $ 214,000,000  
Aggregate Intrinsic Value, vested 205,000,000    
Aggregate Intrinsic Value, exercisable $ 194,000,000    
Stock option, Outstanding at the beginning of year 19,379,677    
Stock option, exercised (1,339,480)    
Stock option, forfeited 0    
Stock option, expired or cancelled 0    
Stock options, Outstanding at the end of year 18,040,197 19,379,677  
Stock option, Vested 17,922,026    
Stock option, Exercisable at End of Year 17,172,815    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Aggregate Intrinsic Value, exercised $ 39,000,000    
Employee Stock Option [Member] | 2014 Omnibus Stock And Performance Incentive Plan Of ConocoPhillips [Member]      
Summary of Stock Options Activity      
Weighted-Average Grant-Date Fair Value, granted     $ 9.18
Aggregate Intrinsic Value, exercised   $ 94,000,000 $ 4,000,000
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted-average remaining contractual term of outstanding options 4 years 5 months 4 days    
Weighted-average remaining contractual term of vested options 4 years 4 months 28 days    
Weighted-average remaining contractual term exercisable 4 years 3 months 14 days    
Weighted-Average Grant-Date Fair Value, granted     $ 9.18
Aggregate Intrinsic Value, exercised   $ 94,000,000 $ 4,000,000
Cash received from exercise of stock options $ 49,000,000    
Tax benefit from exercise of options 13,000,000    
Unrecognized compensation cost from stock options $ 0