Quarterly report pursuant to Section 13 or 15(d)

LONG-TERM DEBT - Narrative (Details)

v3.10.0.1
LONG-TERM DEBT - Narrative (Details)
9 Months Ended
Dec. 07, 2012
USD ($)
Sep. 30, 2018
USD ($)
helicopter
Sep. 30, 2017
USD ($)
Mar. 07, 2018
USD ($)
Mar. 06, 2018
USD ($)
Debt Instrument [Line Items]          
Payments of debt issuance costs   $ 1,295,000      
Payments on long-term debt   $ 42,562,000 $ 24,745,000    
Number of helicopters sold | helicopter   1      
Number of helicopters added | helicopter   2      
Number of helicopters | helicopter   3      
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   $ 1,200,000 (1,200,000)    
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   0.375%      
Letters of credit outstanding   $ 1,100,000      
Write off of deferred debt issuance cost   400,000      
Payments of debt issuance costs   $ 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   1.50%      
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   2.50%      
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      
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)   10 months      
Tax Disputes | Brazil | Maximum          
Debt Instrument [Line Items]          
Payments on long-term debt   $ 2,300,000