Commitments (Narrative) (Details) - Natural Gas [Member] - 2016 Deliveries [Member]	Mar. 31, 2016 MMcf / D CAD / Mcf
Commitments and Contingencies Disclosure [Line Items]
Notional amount, per day \| MMcf / D	59
Swap price \| CAD / Mcf	3.19

Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

Name:	invest_DerivativeNonmonetaryNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant