Revenue from Contracts with Customers (Current Long-Term Contracts Outstanding) (Details)	Mar. 31, 2021 Boe MMcf
Q4 2021 | United States
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, oil quantity per day | Boe	17,000
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 Alberta AECO 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 Alberta AECO 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 Alberta AECO fixed prices
Disaggregation of Revenue [Line Items]
Remaining performance obligation	134
Q4 2026 | Canada | Contracts to sell natural gas at USD Index pricing
Disaggregation of Revenue [Line Items]
Remaining performance obligation	49
Q3 2023 | Canada | Contracts to sell natural gas liquids at various CAD pricing
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, oil quantity per day | Boe	730