XML 84 R72.htm IDEA: XBRL DOCUMENT v3.8.0.1
Fair Value Measurements - Additional Information (Detail)
 3 Months Ended
Mar. 31, 2018
USD ($)
Counterparty
Mar. 31, 2017
USD ($)
Dec. 31, 2017
USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]      
Interest and dividends $ 168,000 $ 118,000  
Mark-to-market gain (loss) (7,500,000) 1,500,000  
Impairment on natural gas and oil properties 7,312,000 $ 0  
Allowance for doubtful accounts on accounts receivable $ 7,112,000   $ 7,111,000
Number of financial institutions included in counter parties | Counterparty 19    
Number of counterparties | Counterparty 5    
Net derivative liability $ 15,400,000    
Oklahoma      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]      
Impairment on natural gas and oil properties $ 7,300,000