Annual report pursuant to Section 13 and 15(d)

VARIABLE INTEREST ENTITIES AND EQUITY INVESTMENTS AND ADVANCES Schedule of Equity Method Investments (Details)

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VARIABLE INTEREST ENTITIES AND EQUITY INVESTMENTS AND ADVANCES Schedule of Equity Method Investments (Details) - USD ($)
$ in Thousands
Oct. 01, 2015
Dec. 31, 2017
Dec. 31, 2016
Sep. 30, 2015
Jul. 01, 2011
Schedule of Equity Method Investments [Line Items]          
Equity Method Investments   $ 30,056 $ 29,266    
Cumulative unfunded net losses of equity investees   $ 2,900 1,100    
Dart Helicopter Services LLC          
Schedule of Equity Method Investments [Line Items]          
Ownership   50.00%      
Equity Method Investments   $ 26,128 24,782    
Era Training Center          
Schedule of Equity Method Investments [Line Items]          
Ownership   50.00%      
Equity Method Investments   $ 3,928 $ 4,484    
Aeroleo          
Schedule of Equity Method Investments [Line Items]          
Ownership         50.00%
Era do Brazil          
Schedule of Equity Method Investments [Line Items]          
Ownership       50.00% 50.00%
Aeroleo | Variable Interest Entity, Primary Beneficiary          
Schedule of Equity Method Investments [Line Items]          
Remaining ownership percentage acquired 50.00%        
Era do Brazil          
Schedule of Equity Method Investments [Line Items]          
Remaining ownership percentage acquired 50.00%        
Era do Brazil | Variable Interest Entity, Primary Beneficiary          
Schedule of Equity Method Investments [Line Items]          
Remaining ownership percentage acquired 50.00%