Annual report pursuant to Section 13 and 15(d)

VARIABLE INTEREST ENTITIES AND EQUITY INVESTMENTS AND ADVANCES Era Training Center Narrative (Details)

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VARIABLE INTEREST ENTITIES AND EQUITY INVESTMENTS AND ADVANCES Era Training Center Narrative (Details)
$ in Millions
 12 Months Ended
Dec. 31, 2016
USD ($)
flight_simulator
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Equity Method Investee | Training Services      
Schedule of Equity Method Investments [Line Items]      
Notes receivable to related party $ 4.0 $ 4.4  
Era Training Center      
Schedule of Equity Method Investments [Line Items]      
Number of flight simulators purchased | flight_simulator 2    
Era Training Center | Equity Method Investee      
Schedule of Equity Method Investments [Line Items]      
Notes receivable interest rate 6.00%    
Quarterly principal and interest payment on notes receivable with related party $ 0.1    
Era Training Center | Equity Method Investee | Helicopter, Management and Other Services      
Schedule of Equity Method Investments [Line Items]      
Expenses from transactions with related party 0.2 0.4 $ 0.4
Era Training Center | Equity Method Investee | Training Services      
Schedule of Equity Method Investments [Line Items]      
Expenses from transactions with related party $ 0.6 $ 0.5 $ 0.7