Quarterly report pursuant to Section 13 or 15(d)

Subsequent Events (Narrative) (Details)

v3.4.0.3
Subsequent Events (Narrative) (Details)
$ in Thousands
 3 Months Ended
Apr. 25, 2016
USD ($)
shares
Apr. 19, 2016
USD ($)
a
shares
Apr. 15, 2016
USD ($)
a
Mar. 31, 2016
USD ($)
Mar. 31, 2015
USD ($)
Subsequent Event [Line Items]          
Proceeds from issuance of common stock       $ 94,949 $ 65,546
Subsequent Event [Member]          
Subsequent Event [Line Items]          
Shares of common stock issued in public offering | shares 25,300,000        
Proceeds from issuance of common stock $ 206,198        
Central Midland Basin Texas [Member] | Subsequent Event [Member]          
Subsequent Event [Line Items]          
Gas and oil area, developed and undeveloped, gross | a   17,298      
Gas and oil area, developed and undeveloped, net | a   14,089      
Shares of common stock issued in acquisition | shares   9,333,333      
Consideration transferred   $ 220,000      
Working interest   81.00%      
Net revenue interest   61.00%      
Western Reagan County, Texas [Member] | AMI Transaction [Member] | Subsequent Event [Member]          
Subsequent Event [Line Items]          
Gas and oil area, developed and undeveloped, net | a     4,745    
Consideration transferred     $ 33,000    
Percentage of ownership interest acquired     55.00%    
TRP Energy, LLC [Member] | Western Reagan County, Texas [Member] | AMI Transaction [Member] | Subsequent Event [Member]          
Subsequent Event [Line Items]          
Sale of ownership interest, percent     27.50%