Quarterly report pursuant to Section 13 or 15(d)

LONG-TERM DEBT - Narrative (Details)

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LONG-TERM DEBT - Narrative (Details) - USD ($)
3 Months Ended 12 Months Ended
Dec. 07, 2012
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Dec. 31, 2016
Mar. 07, 2018
Mar. 06, 2018
Debt Instrument [Line Items]              
Debt issuance cost   $ 1,981,000   $ 2,067,000      
Write off of deferred debt issuance cost       $ 400,000      
Payments of debt issuance costs   1,295,000     $ 1,300,000    
Payments on long-term debt   (14,259,000) $ (6,581,000)        
7.750% Senior Notes (excluding unamortized discount) | Senior Unsecured Notes Due December 15, 2022              
Debt Instrument [Line Items]              
Aggregate principal amount $ 200,000,000.0            
Stated interest rate 7.75%            
Proceeds from issuance of long-term debt $ 191,900,000            
Promissory notes              
Debt Instrument [Line Items]              
Payments on long-term debt   (600,000) (400,000)        
Senior secured revolving credit facility              
Debt Instrument [Line Items]              
Maximum borrowing amount           $ 125,000,000.0 $ 200,000,000.0
Interest coverage ratio           175.00%  
Senior secured leverage ratio           325.00%  
Increase in commitments due to accordion feature   $ 50,000,000.0          
Commitment fee basis point   0.50%          
Outstanding borrowings   $ 27,000,000          
Letters of credit outstanding   $ 1,300,000          
Senior secured revolving credit facility | Minimum              
Debt Instrument [Line Items]              
Commitment fee basis point   0.375%          
Senior secured revolving credit facility | Maximum              
Debt Instrument [Line Items]              
Commitment fee basis point   0.50%          
Senior secured revolving credit facility | Base Rate              
Debt Instrument [Line Items]              
Basis spread on variable rate   1.25%          
Senior secured revolving credit facility | Base Rate | Minimum              
Debt Instrument [Line Items]              
Basis spread on variable rate   1.25%          
Senior secured revolving credit facility | Base Rate | Maximum              
Debt Instrument [Line Items]              
Basis spread on variable rate   2.50%          
Senior secured revolving credit facility | London Interbank Offered Rate (LIBOR)              
Debt Instrument [Line Items]              
Basis spread on variable rate   2.25%          
Senior secured revolving credit facility | London Interbank Offered Rate (LIBOR) | Minimum              
Debt Instrument [Line Items]              
Basis spread on variable rate   2.25%          
Senior secured revolving credit facility | London Interbank Offered Rate (LIBOR) | Maximum              
Debt Instrument [Line Items]              
Basis spread on variable rate   3.50%          
Letter of Credit              
Debt Instrument [Line Items]              
Maximum borrowing amount   $ 50,000,000.0          
Aeroleo              
Debt Instrument [Line Items]              
Payments on long-term debt   $ (1,700,000)          
Foreign Tax Authority | Aeroleo              
Debt Instrument [Line Items]              
Taxes, penalties and interest     $ 200,000        
Tax Disputes | Brazil | Minimum              
Debt Instrument [Line Items]              
Duration of repayment for tax dispute (in months)   16 months          
Tax Disputes | Brazil | Maximum              
Debt Instrument [Line Items]              
Duration of repayment for tax dispute (in months)   56 months