Forward Contracts Classified as Derivatives - Recognized but unrealized net gains on forward energy and capacity purchases and sales expected to be realized on settlement (Details 2) (Forward Electricity Contracts, USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Derivative [Line Items]
Net Gain	$ 40
3rd Qtr 2013
Derivative [Line Items]
Net Gain	$ 40