Commitments (Narrative) (Details) - Natural Gas [Member]	Jun. 30, 2016 MMcf / D MMcf / d CAD / Mcf
2016 Deliveries [Member]
Commitments and Contingencies Disclosure [Line Items]
Notional amount, per day | MMcf / D	99
Swap price (per share)	3.00
January 2017 Through December 2020 Deliveries [Member]
Commitments and Contingencies Disclosure [Line Items]
Notional amount, per day | MMcf / D	40
Swap price (per share)	2.71
January 2017 Through December 2020 Deliveries, Contract 2 [Member]
Commitments and Contingencies Disclosure [Line Items]
Notional amount, per day | MMcf / d	19
Swap price (per share)	3.00