Quarterly report pursuant to Section 13 or 15(d)

PROPERTY AND EQUIPMENT (Narrative) (Details)

v3.10.0.1
PROPERTY AND EQUIPMENT (Narrative) (Details)
 3 Months Ended 9 Months Ended
Sep. 30, 2018
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2018
USD ($)
usd_per_mcf
Sep. 30, 2017
USD ($)
usd_per_mcf
Dec. 31, 2017
USD ($)
Property, Plant and Equipment [Line Items]          
Impairment of oil and gas properties     $ 0 $ 0  
Cumulative capitalization of general and administrative costs incurred and capitalized to the full cost pool $ 194,400,000   194,400,000    
Capitalized general and administrative costs 10,600,000 $ 8,900,000 $ 28,800,000 $ 25,600,000  
Depletion per Mcfe of gas equivalent (usd per Mcfe) | usd_per_mcf     0.94 0.89  
Capitalized costs of oil and natural gas properties excluded from amortization $ 2,925,145,000   $ 2,925,145,000   $ 2,912,974,000
Non-producing leases, extension term 5 years   5 years    
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