Annual report pursuant to Section 13 and 15(d)

FAIR VALUE MEASUREMENTS - Additional Information (Details)

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FAIR VALUE MEASUREMENTS - Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Property and equipment impairment expense $ 0 $ 0 $ 6,305,000  
Net carrying value of property and equipment 912,846,000 470,910,000    
Additions or disposals of goodwill 0 0 0  
Goodwill impairment expense $ 0 0 1,177,000  
Drilling        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Property and equipment impairment expense     6,300,000  
Net carrying value of property and equipment       $ 15,000,000
Surface air drilling unit        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Goodwill impairment expense     1,200,000  
Fair value of the reporting unit     3,800,000  
Carrying value of reporting unit     4,200,000  
Implied fair value of goodwill     0  
Interest rate swap        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Gain (loss) interest rate swap   300,000 200,000  
Interest rate swap | Recurring basis        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Fair value of interest rate swap liability   $ 0 $ 300,000