Revenue from Contracts with Customers (Current Long-Term Contracts Outstanding) (Details) Boe in Thousands	Sep. 30, 2020 Boe MMcf
Q4 2021 | United States
Disaggregation of Revenue [Line Items]
Remaining performance obligation, oil quantity per day | Boe	17
Q4 2021 | Canada | Contracts to sell natural gas at USD Index pricing
Disaggregation of Revenue [Line Items]
Remaining performance obligation	10
Q4 2020 | Canada | Contracts to sell natural gas at Alberta AECO fixed prices
Disaggregation of Revenue [Line Items]
Remaining performance obligation	59
Q4 2020 | Canada | Contracts to sell natural gas at USD Index pricing
Disaggregation of Revenue [Line Items]
Remaining performance obligation	60
Q4 2022 | Canada | Contracts to sell natural gas at USD Index pricing
Disaggregation of Revenue [Line Items]
Remaining performance obligation	35
Q4 2022 | Canada | Contracts to sell natural gas at Malin USD fixed prices
Disaggregation of Revenue [Line Items]
Remaining performance obligation	20
Q4 2024 | Canada | Contracts to sell natural gas at USD Index pricing
Disaggregation of Revenue [Line Items]
Remaining performance obligation	30
Q4 2026 | Canada | Contracts to sell natural gas at USD Index pricing
Disaggregation of Revenue [Line Items]
Remaining performance obligation	49