Quarterly report pursuant to Section 13 or 15(d)

Acquisitions (Fair Value of Net Assets Acquired ) (Details)

v3.5.0.2
Acquisitions (Fair Value of Net Assets Acquired ) (Details) - USD ($)
$ in Thousands
Aug. 03, 2016
May 26, 2016
May 16, 2016
Jan. 18, 2016
Howard County, Texas [Member] | Big Star Transaction [Member]        
Business Acquisition [Line Items]        
Asset retirement obligations   $ (8)    
Net assets acquired   329,573    
Howard County, Texas [Member] | Big Star Transaction [Member] | Evaluated Oil and Natural Gas Properties [Member]        
Business Acquisition [Line Items]        
Oil and natural gas properties   96,194    
Howard County, Texas [Member] | Big Star Transaction [Member] | Unevaluated Oil and Natural Gas Properties [Member]        
Business Acquisition [Line Items]        
Oil and natural gas properties   $ 233,387    
Casselman-Bohannon Fields [Member]        
Business Acquisition [Line Items]        
Net assets acquired $ 13,000     $ 10,183
Casselman-Bohannon Fields [Member] | Evaluated Oil and Natural Gas Properties [Member]        
Business Acquisition [Line Items]        
Oil and natural gas properties 6,492     5,527
Casselman-Bohannon Fields [Member] | Unevaluated Oil and Natural Gas Properties [Member]        
Business Acquisition [Line Items]        
Oil and natural gas properties $ 6,508     $ 4,656
Western Reagan County, Texas [Member] | AMI Transaction [Member]        
Business Acquisition [Line Items]        
Asset retirement obligations     $ (8)  
Net assets acquired     33,012  
Western Reagan County, Texas [Member] | AMI Transaction [Member] | Evaluated Oil and Natural Gas Properties [Member]        
Business Acquisition [Line Items]        
Oil and natural gas properties     15,951  
Western Reagan County, Texas [Member] | AMI Transaction [Member] | Unevaluated Oil and Natural Gas Properties [Member]        
Business Acquisition [Line Items]        
Oil and natural gas properties     $ 17,069