Annual report pursuant to Section 13 and 15(d)

VARIABLE INTEREST ENTITIES AND EQUITY INVESTMENTS AND ADVANCES Lake Palma Narrative (Details)

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VARIABLE INTEREST ENTITIES AND EQUITY INVESTMENTS AND ADVANCES Lake Palma Narrative (Details)
$ in Thousands
12 Months Ended
Jul. 24, 2014
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Jul. 23, 2014
helicopter
Schedule of Equity Method Investments [Line Items]          
Proceeds from sale of interest in equity investees   $ 0 $ 0 $ 6,381  
Gain on consolidation of subsidiary   $ 0 $ 0 $ 1,518  
Lake Palma          
Schedule of Equity Method Investments [Line Items]          
Number of helicopters operated | helicopter         7
Lake Palma          
Schedule of Equity Method Investments [Line Items]          
Ownership percentage 51.00%        
Proceeds from sale of interest in equity investees $ 9,300        
Gain on consolidation of subsidiary 1,500        
Debt obligations $ 2,900