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 9 Months Ended
May 04, 2017
USD ($)
bank
Dec. 21, 2016
USD ($)
Dec. 13, 2016
USD ($)
Dec. 12, 2016
Oct. 14, 2016
USD ($)
Jan. 31, 2016
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
May 05, 2017
USD ($)
Mar. 29, 2017
USD ($)
Dec. 31, 2016
USD ($)
Oct. 31, 2016
USD ($)
Jun. 04, 2015
USD ($)
Apr. 21, 2015
USD ($)
Aug. 18, 2014
USD ($)
Dec. 21, 2012
USD ($)
Oct. 17, 2012
USD ($)
Debt Instrument [Line Items]                                      
Capitalized interest expense, undeveloped properties             $ 2,100,000 $ 4,700,000 $ 8,800,000 $ 7,700,000                  
Capitalized interest expense, building construction                 8,753,000 8,920,000                  
Debt issuance costs, net             30,111,000   30,111,000       $ 27,174,000            
Construction loans                                      
Debt Instrument [Line Items]                                      
Capitalized interest expense, building construction             0 $ 500,000 0 $ 1,200,000                  
Debt issuance costs, net             $ 100,000   $ 100,000                    
Amended and restated credit agreement | Maximum                                      
Debt Instrument [Line Items]                                      
Debt covenant ratio for future EBITDAX             4.00   4.00                    
Amended and restated credit agreement | Revolving credit agreement                                      
Debt Instrument [Line Items]                                      
Debt covenant ratio for EBITDAX             3.00   3.00                    
7.75% Senior Notes due 2020 | Senior notes                                      
Debt Instrument [Line Items]                                      
Long-term debt             $ 0   $ 0       0            
Stated interest rate, percent             7.75%   7.75%                    
Debt instrument, amount                                 $ 600,000,000.0    
Debt instrument, amount repurchased                           $ 600,000,000.0          
6.000% Senior Notes due 2024 | Senior notes                                      
Debt Instrument [Line Items]                                      
Long-term debt             $ 650,000,000   $ 650,000,000       650,000,000            
Stated interest rate, percent         6.00%   6.00%   6.00%         6.00%          
Debt instrument, amount         $ 650,000,000.0                            
Proceeds from issuance of Senior Notes         $ 638,900,000                            
Debt issuance costs, net             $ 10,200,000   $ 10,200,000                    
6.625% Senior Notes due 2023 | Senior notes                                      
Debt Instrument [Line Items]                                      
Long-term debt             $ 350,000,000   $ 350,000,000       350,000,000            
Stated interest rate, percent             6.625%   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             $ 5,500,000   $ 5,500,000                    
6.375% Senior Notes due 2025 | Senior notes                                      
Debt Instrument [Line Items]                                      
Long-term debt             $ 600,000,000   $ 600,000,000       600,000,000            
Stated interest rate, percent   6.375%         6.375%   6.375%                    
Debt instrument, amount   $ 600,000,000.0                                  
Proceeds from issuance of Senior Notes   $ 584,700,000                                  
Debt issuance costs, net             $ 14,300,000   $ 14,300,000                    
Nova Scotia, Amegy, KeyBank | Revolving credit agreement                                      
Debt Instrument [Line Items]                                      
Credit facility interest rate at the eurodollar rate                 3.74%                    
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Base rate | Minimum                                      
Debt Instrument [Line Items]                                      
Stated interest rate, percent             1.00%   1.00%                    
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Base rate | Maximum                                      
Debt Instrument [Line Items]                                      
Stated interest rate, percent             2.00%   2.00%                    
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             2.00%   2.00%                    
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Eurodollar | Maximum                                      
Debt Instrument [Line Items]                                      
Stated interest rate, percent             3.00%   3.00%                    
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Amended and restated credit agreement                                      
Debt Instrument [Line Items]                                      
Maximum borrowing capacity             $ 1,500,000,000.0   $ 1,500,000,000.0                    
Required minimum down payment, percent     85.00% 80.00%                              
Minimum acquisition payment limit                       $ 50,000,000              
Minimum disposition of property limit                       $ 50,000,000              
Borrowing base $ 700,000,000           1,000,000,000   1,000,000,000                    
Number of banks added to syndicate | bank 5                                    
Long-term debt             365,000,000   365,000,000       0            
Remaining borrowing capacity             397,500,000   397,500,000                    
Nova Scotia, Amegy, KeyBank | Unsecured debt | Amended and restated credit agreement                                      
Debt Instrument [Line Items]                                      
Maximum borrowing capacity     $ 1,600,000,000.0                                
Basis spread, percent     0.50%                                
Nova Scotia, Amegy, KeyBank | Letter of credit | Amended and restated credit agreement                                      
Debt Instrument [Line Items]                                      
Maximum borrowing capacity             1,200,000,000.0   $ 1,200,000,000.0   $ 1,000,000.0                
Basis spread, percent                 0.50%                    
Credit facility outstanding             237,500,000   $ 237,500,000                    
Line of credit facility, elected commitment             1,000,000,000.0   1,000,000,000.0                    
Disposition costs, maximum expenses allowed                 3,000,000.0                    
Wells Fargo Bank | October Notes | Senior notes                                      
Debt Instrument [Line Items]                                      
Stated interest rate, percent                                     7.75%
Debt instrument, amount                                     $ 250,000,000.0
Wells Fargo Bank | December Notes | Senior notes                                      
Debt Instrument [Line Items]                                      
Stated interest rate, percent                                   7.75%  
Debt instrument, amount                                   $ 50,000,000.0  
Wells Fargo Bank | August Notes | Senior notes                                      
Debt Instrument [Line Items]                                      
Stated interest rate, percent                                 7.75%    
Debt instrument, amount                                 $ 300,000,000.0    
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             $ 23,817,000   $ 23,817,000       $ 21,049,000