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Gas Reserves (Tables)
 12 Months Ended
Dec. 31, 2015
Gas Reserves [Abstract]  
Gas Reserves Table [Text Block]
In thousands
 
2015
 
2014
Gas reserves, current
 
$
17,094

 
$
20,020

Gas reserves, non-current
 
170,453

 
167,190

Less: Accumulated amortization
 
55,901

 
37,910

Total gas reserves(1)
 
131,646

 
149,300

Less: Deferred taxes on gas reserves
 
27,203

 
18,551

Net investment in gas reserves(1)
 
$
104,443

 
$
130,749