Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt (Narrative) (Details)

v3.8.0.1
Long-Term Debt (Narrative) (Details)
1 Months Ended 3 Months Ended
Nov. 21, 2017
May 04, 2017
USD ($)
bank
Dec. 21, 2016
USD ($)
Oct. 14, 2016
USD ($)
Jan. 31, 2016
Mar. 31, 2018
USD ($)
Mar. 31, 2017
USD ($)
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Oct. 11, 2017
USD ($)
May 05, 2017
USD ($)
Mar. 29, 2017
USD ($)
Jun. 04, 2015
USD ($)
Apr. 21, 2015
USD ($)
Debt Instrument [Line Items]                            
Capitalized interest expense, undeveloped properties           $ 800,000 $ 3,100,000              
Capitalized interest expense, building construction           843,000 3,122,000              
Debt issuance costs, net           33,927,000     $ 34,781,000          
Construction loans                            
Debt Instrument [Line Items]                            
Capitalized interest expense, building construction           0 $ 0              
Debt issuance costs, net           $ 100,000                
Amended and restated credit agreement | Maximum                            
Debt Instrument [Line Items]                            
Debt covenant ratio for future EBITDAX           4.00                
Amended and restated credit agreement | Revolving credit agreement                            
Debt Instrument [Line Items]                            
Debt covenant ratio for EBITDAX           3.00                
7.75% Senior Notes due 2020 | Senior notes                            
Debt Instrument [Line Items]                            
Stated interest rate, percent           7.75%                
6.000% Senior Notes due 2024 | Senior notes                            
Debt Instrument [Line Items]                            
Long-term debt           $ 650,000,000     650,000,000          
Stated interest rate, percent       6.00%   6.00%                
Debt instrument, amount       $ 650,000,000.0                    
Proceeds from issuance of Senior Notes       $ 638,900,000                    
Debt issuance costs, net           $ 9,600,000                
6.625% Senior Notes due 2023 | Senior notes                            
Debt Instrument [Line Items]                            
Long-term debt           $ 350,000,000     350,000,000          
Stated interest rate, percent           6.625%               6.625%
Debt instrument, amount                           $ 350,000,000.0
Long term debt, net of initial purchaser discounts and commissions and estimated offering expenses                           $ 343,600,000
Debt issuance costs, net           $ 5,000,000                
6.375% Senior Notes due 2025 | Senior notes                            
Debt Instrument [Line Items]                            
Long-term debt           $ 600,000,000     600,000,000          
Stated interest rate, percent     6.375%     6.375%                
Debt instrument, amount     $ 600,000,000.0                      
Proceeds from issuance of Senior Notes     $ 584,700,000                      
Debt issuance costs, net           $ 13,600,000                
6.375% Senior Notes Due 2026 | Senior notes                            
Debt Instrument [Line Items]                            
Long-term debt           450,000,000     450,000,000          
Stated interest rate, percent                   6.375%        
Debt instrument, amount                   $ 450,000,000.0        
Long term debt, net of initial purchaser discounts and commissions and estimated offering expenses                   $ 444,100,000        
Debt issuance costs, net           $ 5,500,000                
Nova Scotia, Amegy, KeyBank | Revolving credit agreement                            
Debt Instrument [Line Items]                            
Credit facility interest rate at the eurodollar rate           3.52%                
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Base rate | Minimum                            
Debt Instrument [Line Items]                            
Stated interest rate, percent           0.50%                
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Base rate | Maximum                            
Debt Instrument [Line Items]                            
Stated interest rate, percent           1.50%                
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Federal funds rate                            
Debt Instrument [Line Items]                            
Basis spread, percent           0.50%                
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Eurodollar                            
Debt Instrument [Line Items]                            
Basis spread, percent           1.00%                
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Eurodollar | Minimum                            
Debt Instrument [Line Items]                            
Stated interest rate, percent           1.50%                
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Eurodollar | Maximum                            
Debt Instrument [Line Items]                            
Stated interest rate, percent           2.50%                
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Amended and restated credit agreement                            
Debt Instrument [Line Items]                            
Maximum borrowing capacity           $ 1,500,000,000.0                
Minimum acquisition payment limit                       $ 50,000,000    
Minimum disposition of property limit                       $ 50,000,000    
Borrowing base   $ 700,000,000       1,200,000,000.0         $ 1,000,000,000      
Number of banks added to syndicate | bank   5                        
Increase (decrease) in interest rate 0.50%                          
Long-term debt           200,000,000     0          
Remaining borrowing capacity           $ 557,200,000                
Nova Scotia, Amegy, KeyBank | Letter of credit | Amended and restated credit agreement                            
Debt Instrument [Line Items]                            
Basis spread, percent           0.25%                
Credit facility outstanding           $ 242,800,000                
Line of credit facility, elected commitment           1,000,000,000.0                
Disposition costs, maximum expenses allowed           3,000,000.0                
InterBank | Revolving credit agreement | Construction loans                            
Debt Instrument [Line Items]                            
Maximum borrowing capacity                         $ 24,500,000.0  
Stated interest rate, percent                         4.50%  
InterBank | Letter of credit | Construction loans                            
Debt Instrument [Line Items]                            
Required minimum down payment, percent         30.00%                  
Long-term debt           $ 23,579,000     $ 23,724,000          
Scenario, Forecast | Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Amended and restated credit agreement                            
Debt Instrument [Line Items]                            
Borrowing base               $ 1,400,000,000.0