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Long-Term Debt - Credit Facility - Additional Information (Detail) - USD ($)
$ in Thousands
6 Months Ended
Jun. 24, 2019
Jun. 30, 2019
Dec. 31, 2018
Jun. 30, 2018
Line Of Credit Facility [Line Items]        
Proceeds from Beta Decommissioning Trust account $ 90,000 $ 0    
Letters of credit outstanding   1,700    
New Revolving Credit Facility [Member]        
Line Of Credit Facility [Line Items]        
Borrowing base   425,000    
Proceeds from Beta Decommissioning Trust account $ 90,000      
Revolving credit facility   $ 175,000 $ 294,000  
Emergence Credit Facility [Member]        
Line Of Credit Facility [Line Items]        
Revolving credit facility       $ 1,000,000