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Summary of Significant Accounting Policies - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2020
USD ($)
Counterparty
Customer
Dec. 31, 2019
USD ($)
Customer
Dec. 31, 2018
USD ($)
Customer
Summary Of Significant Accounting Policies [Line Items]      
Net brokered margin gain (loss) $ (14,200,000) $ (14,200,000) $ (16,300,000)
Allowance for doubtful accounts on accounts receivable 3,004,000 8,784,000  
Bad debt (income) expense 400,000 4,341,000 (1,000,000)
Net book value of unproved properties [1] 859,766,000 868,180,000 2,110,277,000
Abandonment and impairment of unproved properties 19,334,000 1,235,342,000 514,994,000
Depreciation expense $ 2,600,000 5,000,000.0 $ 6,000,000.0
Maximum amount term for short term leases 1 year    
Marketable securities held in deferred compensation plans $ 63,900,000 62,000,000.0  
Other investments including surface acreage $ 11,900,000 $ 9,600,000  
Number of customers accounted more than 10% of total oil and gas revenues | Customer 0 1 1
Number of counterparties | Counterparty 5    
Number of financial institutions included in counter parties | Counterparty 20    
Number of counterparties amount payable | Counterparty 3    
Number of counterparties amount receivable | Counterparty 2    
Counterparties not in Facility      
Summary Of Significant Accounting Policies [Line Items]      
Net derivative liability $ 4,500,000    
Counterparties in a Liability position      
Summary Of Significant Accounting Policies [Line Items]      
Net derivative liability 4,500,000    
Counterparties in a Receivable position      
Summary Of Significant Accounting Policies [Line Items]      
Derivative amount receivable $ 5,200,000    
Maximum      
Summary Of Significant Accounting Policies [Line Items]      
Lessee, operating lease, contract term 1 month    
Other property and equipment | Minimum      
Summary Of Significant Accounting Policies [Line Items]      
Useful life of assets 3 years    
Other property and equipment | Maximum      
Summary Of Significant Accounting Policies [Line Items]      
Useful life of assets 10 years    
North Louisiana      
Summary Of Significant Accounting Policies [Line Items]      
Abandonment and impairment of unproved properties   $ 1,200,000,000  
[1] Includes capitalized asset retirement costs and the associated accumulated amortization.