Annual report pursuant to Section 13 and 15(d)

Contingencies - Narrative (Details)

v3.6.0.2
Contingencies - Narrative (Details)
1 Months Ended 6 Months Ended 12 Months Ended
Jul. 29, 2016
defendant
Feb. 09, 2016
defendant
Sep. 30, 2014
USD ($)
Jul. 29, 2016
claim
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Loss Contingencies [Line Items]              
Number of new claims filed | claim       2      
Amount of settlement litigation against     $ (18,000,000)        
Insurance proceeds         $ (5,718,000) $ (10,015,000) $ 0
Uninsured cash amount         1,500,000,000    
Maximum              
Loss Contingencies [Line Items]              
Cash, FDIC insured amount         $ 250,000    
Judicial District Court for the Parish of Cameron              
Loss Contingencies [Line Items]              
Number of defendants | defendant   26          
Judicial District Court for the Parish of Vermillion              
Loss Contingencies [Line Items]              
Number of defendants | defendant 40            
Customer concentration risk | Capacity | British Petroleum | Natural gas, per MMbtu              
Loss Contingencies [Line Items]              
Percentage of total production sold by customer         68.00% 79.00% 40.00%
Customer concentration risk | Capacity | DTE Energy Trading Inc | Natural gas, per MMbtu              
Loss Contingencies [Line Items]              
Percentage of total production sold by customer         10.00% 14.00% 32.00%
Customer concentration risk | Capacity | Shell Trading Company | Oil derivatives              
Loss Contingencies [Line Items]              
Percentage of total production sold by customer         72.00% 90.00% 99.00%
Customer concentration risk | Capacity | Marathon Oil Corporation | Oil derivatives              
Loss Contingencies [Line Items]              
Percentage of total production sold by customer         24.00% 10.00%  
Customer concentration risk | Capacity | Markwest Utica              
Loss Contingencies [Line Items]              
Percentage of total production sold by customer             100.00%
Customer concentration risk | Capacity | Markwest Utica | Natural gas liquids              
Loss Contingencies [Line Items]              
Percentage of total production sold by customer         74.00% 76.00%  
Customer concentration risk | Capacity | Antero Resources | Natural gas liquids              
Loss Contingencies [Line Items]              
Percentage of total production sold by customer         23.00% 24.00%  
Customer concentration risk | Capacity | Hess | Natural gas, per MMbtu              
Loss Contingencies [Line Items]              
Percentage of total production sold by customer             19.00%