Annual report pursuant to Section 13 and 15(d)

Property and Equipment - Summary of Oil and Gas Properties Not Subject to Amortization (Details)

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Property and Equipment - Summary of Oil and Gas Properties Not Subject to Amortization (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Property, Plant and Equipment [Line Items]        
Acquisition costs $ 1,511,685 $ 129,741 $ 429,897 $ 824,363
Acquisition costs, total 2,895,686      
Exploration costs 0 0 0 0
Exploration costs, total 0      
Development costs 5,076 4,607 3,635 2,214
Development costs, total 15,532      
Capitalized interest 3,871 (536) (1,141) (438)
Capitalized interest, total 1,756      
Total oil and natural gas properties not subject to amortization 1,520,632 133,812 $ 432,391 $ 826,139
Total oil and natural gas properties not subject to amortization, total 2,912,974 $ 1,580,305    
Utica        
Property, Plant and Equipment [Line Items]        
Total oil and natural gas properties not subject to amortization, total 1,513,452      
MidContinent        
Property, Plant and Equipment [Line Items]        
Total oil and natural gas properties not subject to amortization, total 1,396,642      
Niobrara        
Property, Plant and Equipment [Line Items]        
Total oil and natural gas properties not subject to amortization, total 2,184      
Southern Louisiana        
Property, Plant and Equipment [Line Items]        
Total oil and natural gas properties not subject to amortization, total 552      
Bakken        
Property, Plant and Equipment [Line Items]        
Total oil and natural gas properties not subject to amortization, total 99      
Other        
Property, Plant and Equipment [Line Items]        
Total oil and natural gas properties not subject to amortization, total $ 45