Annual report pursuant to Section 13 and 15(d)

Property and Equipment - Narrative (Details)

v3.10.0.1
Property and Equipment - Narrative (Details)
12 Months Ended
Dec. 31, 2018
USD ($)
usd_per_mcf
Dec. 31, 2017
USD ($)
usd_per_mcf
Dec. 31, 2016
USD ($)
usd_per_mcf
Property, Plant and Equipment [Line Items]      
Impairment of oil and natural gas properties $ 0 $ 0 $ 715,495,000
Cumulative capitalization to the full cost pool 203,300,000 165,600,000  
Capitalized general and administrative costs $ 37,700,000 $ 35,700,000 $ 29,300,000
Depletion per Mcf of gas equivalent (usd per Mcfe) | usd_per_mcf 0.96 0.90 0.92
Capitalized costs of oil and natural gas properties excluded from amortization $ 2,873,037,000 $ 2,912,974,000  
Minimum      
Property, Plant and Equipment [Line Items]      
Expected number of years amortization will commence 3 years    
Maximum      
Property, Plant and Equipment [Line Items]      
Expected number of years amortization will commence 5 years