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Summary of Significant Accounting Policies - Major Customers and Concentration of Credit Risk (Details)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Shell [Member]      
Revenue, Major Customer [Line Items]      
Percentage of concentration risk 16.00%   14.00%
Anadarko [Member]      
Revenue, Major Customer [Line Items]      
Percentage of concentration risk   13.00%  
Talos [Member]      
Revenue, Major Customer [Line Items]      
Percentage of concentration risk 11.00%