Revenue from Contracts with Customers (Current and Long-Term Contracts Outstanding) (Details)	Jun. 30, 2018 MMcf / d Boe / d $ / Mcf
Alberta AECO Fixed Price [Member]
Disaggregation of Revenue [Line Items]
Fixed price (Cdn/MCF) | $ / Mcf	2.81
End Date, Q2, 2019 [Member] | United States [Member]
Disaggregation of Revenue [Line Items]
Approximate Net Volumes | Boe / d	4,000
End Date, Q3, 2019 [Member] | United States [Member]
Disaggregation of Revenue [Line Items]
Approximate Net Volumes | Boe / d	2,000
End Date, Q4, 2021, 2018 Deliveries [Member] | United States [Member]
Disaggregation of Revenue [Line Items]
Approximate Net Volumes | Boe / d	19,000
End Date, Q4, 2021, 2019-2021 Deliveries [Member] | United States [Member]
Disaggregation of Revenue [Line Items]
Approximate Net Volumes | Boe / d	13,000
End Date, Q4, 2020 [Member] | Canada [Member] | Alberta AECO Fixed Price [Member]
Disaggregation of Revenue [Line Items]
Approximate Net Volumes | MMcf / d	59
End Date, Q4, 2020 [Member] | Canada [Member] | USD Index Pricing [Member]
Disaggregation of Revenue [Line Items]
Approximate Net Volumes | MMcf / d	60
End Date, Q4, 2024 [Member] | Canada [Member] | USD Index Pricing [Member]
Disaggregation of Revenue [Line Items]
Approximate Net Volumes | MMcf / d	30
End Date, Q4, 2026 [Member] | Canada [Member] | USD Index Pricing [Member]
Disaggregation of Revenue [Line Items]
Approximate Net Volumes | MMcf / d	38