Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Major Customers) (Details)

v3.3.1.900
Summary of Significant Accounting Policies (Major Customers) (Details) - Sales Revenue, Goods, Net [Member] - Customer Concentration Risk [Member]
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Concentration Risk [Line Items]      
Concentration Risk, Percentage 100.00% 100.00% 100.00%
Enterprise Crude Oil, LLC [Member]      
Concentration Risk [Line Items]      
Concentration Risk, Percentage 42.00% 51.00% 38.00%
Plains Marketing, L.P. [Member]      
Concentration Risk [Line Items]      
Concentration Risk, Percentage 19.00% 22.00% 15.00%
Permian Transport And Trading [Member]      
Concentration Risk [Line Items]      
Concentration Risk, Percentage 15.00% 7.00%  
Sunoco [Member]      
Concentration Risk [Line Items]      
Concentration Risk, Percentage 9.00% 10.00%  
Shell Trading Company [Member]      
Concentration Risk [Line Items]      
Concentration Risk, Percentage 4.00%   31.00%
Other [Member]      
Concentration Risk [Line Items]      
Concentration Risk, Percentage 11.00% 10.00% 16.00%