XML 22 R50.htm IDEA: XBRL DOCUMENT v2.4.0.8
Derivatives (Narrative - Commodity Future Contracts) (Details) (Cash Flow Hedging [Member], Natural gas contracts [Member], USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2014
MMBTU
Jun. 30, 2013
Jun. 30, 2014
MMBTU
Jun. 30, 2013
Dec. 31, 2013
MMBTU
Derivative [Line Items]          
Natural gas contracts, notional amounts (in millions of BTUs) 3,020,000   3,020,000   1,520,000
Loss on Cash Flow Hedge Ineffectiveness   $ (0.3)   $ (0.3)  
Derivative, additional cash paid (received) on settlement of hedge (0.3) (0.3) (0.8) 0  
Cash flow hedge loss to be reclassified within 12 months     $ 0.2    
Minimum [Member]
         
Derivative [Line Items]          
Forecast of anticipated requirements, percentage of forecast eligible for hedging 40.00%   40.00%    
Maximum [Member]
         
Derivative [Line Items]          
Forecast of anticipated requirements, percentage of forecast eligible for hedging 70.00%   70.00%    
Forecast of commodity requirements, maximum length of time used     18 months