XML 18 R29.htm IDEA: XBRL DOCUMENT v2.4.0.8
Derivative Instruments (Details) (USD $)
3 Months Ended 12 Months Ended
Mar. 31, 2014
MMcf
Mar. 31, 2013
Dec. 31, 2013
MMcf
Natural Gas Hedging Instruments      
Deferred net gains in accumulated other comprehensive income (loss), net of tax $ 39,800,000   $ 61,700,000
Net unrealized gains on derivative commodity instruments 11,100,000    
Margin deposits with brokers 100,000   300,000
Additional collateral limit for below investment grade derivative instruments, as a percentage of the derivative liability 100.00%    
Aggregate fair value of derivative instruments with credit-risk related contingencies 33,500,000    
Collateral posted 0    
Margin deposits remitted by brokers with company 0 0  
Commodity derivatives
     
Natural Gas Hedging Instruments      
Margin deposits with brokers 53,000   266,000
Cash flow hedges | Interest rate derivatives
     
Derivatives designated as hedging instruments      
Amount of (loss) gain reclassified from accumulated OCI into operating revenues (effective portion), net of tax (36,000) (36,000)  
Cash flow hedges | Commodity derivatives
     
Derivatives designated as hedging instruments      
Amount of loss recognized in OCI (effective portion), net of tax (39,194,000) (52,601,000)  
Amount of (loss) gain reclassified from accumulated OCI into operating revenues (effective portion), net of tax (17,263,000) 25,833,000  
Amount of loss recognized in operating revenues (ineffective portion) (22,260,000) (481,000)  
Natural Gas Hedging Instruments      
Absolute quantities of derivative commodity instruments that have been designated and qualify as cash flow or fair value hedges (in Bcf) 352,000   398,000
Fair value hedges | Commodity derivatives
     
Derivatives designated as hedging instruments      
Amount of loss recognized in operating revenues for fair value commodity contracts   (3,539,000)  
Fair value gain recognized in operating revenues for inventory designated as hedged item   4,537,000  
Amount of gain (loss) recognized in income due to exclusion of the spot/forward differential from the assessment of effectiveness of fair value hedges   1,300,000  
Amount of gain (loss) recognized in income due to changes in basis   (300,000)  
Not designated as hedging instruments
     
Derivatives not designated as hedging instruments:      
Amount of loss recognized in operating revenues $ (9,354,000) $ (262,000)