XML 68 R50.htm IDEA: XBRL DOCUMENT v3.5.0.2
Derivative Accounting - Gains and Losses from Derivative Instruments (Details) - Commodity Contracts - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Designated as Hedging Instruments        
Gains and losses from derivative instruments        
Amount reclassified from accumulated other comprehensive income to earnings related to discontinued cash flow hedges $ 0 $ 0 $ 0 $ 0
Designated as Hedging Instruments | Fuel and purchased power        
Gains and losses from derivative instruments        
Loss reclassified from accumulated OCI into income (effective portion realized) (1,016,000) (1,430,000) (1,957,000) (3,773,000)
Not Designated as Hedging Instruments        
Gains and losses from derivative instruments        
Net gain (loss) recognized in income 61,479,000 10,547,000 30,441,000 (34,304,000)
Not Designated as Hedging Instruments | Revenue        
Gains and losses from derivative instruments        
Net gain (loss) recognized in income 585,000 (66,000) 483,000 (114,000)
Not Designated as Hedging Instruments | Fuel and purchased power        
Gains and losses from derivative instruments        
Net gain (loss) recognized in income 60,894,000 10,613,000 29,958,000 (34,190,000)
Other comprehensive income | Designated as Hedging Instruments        
Gains and losses from derivative instruments        
Gain (loss) recognized in OCI on derivative instruments (effective portion) $ 208,000 $ 41,000 $ 60,000 $ (286,000)