Revenue from Contracts with Customers (Current Long-Term Contracts Outstanding) (Details) Boe in Thousands	Sep. 30, 2021 Boe MMcf
Q4 2021 | United States
Disaggregation of Revenue [Line Items]
Revenue, 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 2022 | Canada | Contracts to sell natural gas at USD index pricing
Disaggregation of Revenue [Line Items]
Remaining performance obligation	8
Q4 2022 | Canada | Contracts to sell natural gas at CAD fixed prices
Disaggregation of Revenue [Line Items]
Remaining performance obligation	5
Q4 2022 | Canada | Contracts to sell natural gas at USD index pricing
Disaggregation of Revenue [Line Items]
Remaining performance obligation	20
Q4 2023 | Canada | Contracts to sell natural gas at USD index pricing
Disaggregation of Revenue [Line Items]
Remaining performance obligation	25
Q4 2023 | Canada | Contracts to sell natural gas at CAD fixed prices
Disaggregation of Revenue [Line Items]
Remaining performance obligation	38
Q4 2024 | Canada | Contracts to sell natural gas at USD index pricing
Disaggregation of Revenue [Line Items]
Remaining performance obligation	31
Q4 2024 | Canada | Contracts to sell natural gas at USD index pricing
Disaggregation of Revenue [Line Items]
Remaining performance obligation	15
Q4 2024 | Canada | Contracts to sell natural gas at CAD fixed prices
Disaggregation of Revenue [Line Items]
Remaining performance obligation	100
Q4 2024 | Canada | Contracts to sell natural gas at CAD fixed prices
Disaggregation of Revenue [Line Items]
Remaining performance obligation	34
Q4 2026 | Canada | Contracts to sell natural gas at USD index pricing
Disaggregation of Revenue [Line Items]
Remaining performance obligation	49