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Derivative Instruments (Details)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2017
USD ($)
MMcf
Dec. 31, 2014
MMcf
Dec. 31, 2016
USD ($)
Commodity Member [Member]      
Derivative [Line Items]      
Derivative, Nonmonetary Notional Amount, Volume | MMcf 819,100,000,000 744,700,000,000  
Derivative Liability, Current | $ $ 25,838   $ 67,139
Derivative Liability, Noncurrent | $ 122,747   209,980
Derivative Asset, Noncurrent | $ $ 58,422   $ 29,596
Basis Member [Member]      
Derivative [Line Items]      
Derivative, Nonmonetary Notional Amount, Volume | MMcf 476,800,000,000 482,000,000,000  
Propane [Member]      
Derivative [Line Items]      
Derivative, Nonmonetary Notional Amount, Volume | MMcf 0 126,000