XML 73 R50.htm IDEA: XBRL DOCUMENT v3.8.0.1
Credit Facility - Additional Information (Details)
12 Months Ended
Apr. 25, 2017
USD ($)
Oct. 31, 2016
USD ($)
Oct. 30, 2016
Dec. 31, 2017
USD ($)
Sep. 30, 2017
USD ($)
Jun. 30, 2017
USD ($)
Mar. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Sep. 30, 2016
USD ($)
Jun. 30, 2016
USD ($)
Apr. 15, 2016
USD ($)
Mar. 31, 2016
USD ($)
Line Of Credit Facility [Line Items]                        
Credit facility       $ 388,000,000 $ 362,000,000 $ 393,000,000 $ 388,000,000 $ 316,000,000 $ 299,000,000 $ 285,000,000   $ 116,000,000
Senior Line of Credit                        
Line Of Credit Facility [Line Items]                        
Maximum borrowing capacity       $ 1,000,000,000.0                
Weighted average interest rate (percent)       4.06%       3.26%        
Current ratio       1.0                
Credit facility       $ 388,000,000       $ 316,000,000        
Unused portion of current borrowing base       $ 162,000,000       $ 184,000,000        
Senior Line of Credit | Federal funds effective rate                        
Line Of Credit Facility [Line Items]                        
Interest rate (percent)       0.50%                
Senior Line of Credit | Borrowing Base Utilization Percentage Less Than 50%                        
Line Of Credit Facility [Line Items]                        
Commitment fee payable rate (percent)       0.375%                
Senior Line of Credit | Borrowing Base Utilization Percentage Equal to or Greater Than 50%                        
Line Of Credit Facility [Line Items]                        
Commitment fee payable rate (percent)       0.50%                
Senior Line of Credit | Minimum                        
Line Of Credit Facility [Line Items]                        
Current ratio       1.0                
Senior Line of Credit | Minimum | LIBOR Plus Margin Rate                        
Line Of Credit Facility [Line Items]                        
Interest rate (percent)     1.50%                  
Senior Line of Credit | Minimum | Prime Rate Plus Margin Rate                        
Line Of Credit Facility [Line Items]                        
Interest rate (percent)     0.50%                  
Senior Line of Credit | Maximum                        
Line Of Credit Facility [Line Items]                        
Ratio of total debt to EBITDAX       3.5                
Senior Line of Credit | Maximum | LIBOR Plus Margin Rate                        
Line Of Credit Facility [Line Items]                        
Interest rate (percent)     2.50%                  
Senior Line of Credit | Maximum | Prime Rate Plus Margin Rate                        
Line Of Credit Facility [Line Items]                        
Interest rate (percent)     1.50%                  
Senior Line of Credit | Revolving Credit Facility                        
Line Of Credit Facility [Line Items]                        
Borrowing base $ 550,000,000 $ 500,000,000.0                 $ 450,000,000.0  
Debt instrument, term 5 years                      
Borrowing base threshold (percent)       50.00%                
Senior Line of Credit | Revolving Credit Facility | Minimum | LIBOR Plus Margin Rate                        
Line Of Credit Facility [Line Items]                        
Interest rate (percent)   2.00%                    
Senior Line of Credit | Revolving Credit Facility | Minimum | Prime Rate Plus Margin Rate                        
Line Of Credit Facility [Line Items]                        
Interest rate (percent)   1.00%                    
Senior Line of Credit | Revolving Credit Facility | Maximum | LIBOR Plus Margin Rate                        
Line Of Credit Facility [Line Items]                        
Interest rate (percent)   3.00%                    
Senior Line of Credit | Revolving Credit Facility | Maximum | Prime Rate Plus Margin Rate                        
Line Of Credit Facility [Line Items]                        
Interest rate (percent)   2.00%