Annual report pursuant to Section 13 and 15(d)

Note 9 - Derivative Instruments and Hedging Strategies (Details Textual)

v3.19.1
Note 9 - Derivative Instruments and Hedging Strategies (Details Textual)
$ in Thousands, € in Millions
12 Months Ended
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2018
EUR (€)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax $ 1,939 $ (214) $ 2,493  
Derivative, Fair Value, Net, Total 6,900      
Interest Rate Swap [Member]        
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax $ (1,939) 214 (2,493)  
Interest Rate Swap [Member] | OSV Partners [Member]        
Derivative, Number of Instruments Held, Total 2     2
Derivative, Notional Amount $ 27,900      
Interest Rate Swap [Member] | OSV Partners [Member] | Minimum [Member]        
Derivative, Fixed Interest Rate 1.89%     1.89%
Interest Rate Swap [Member] | OSV Partners [Member] | Maximum [Member]        
Derivative, Fixed Interest Rate 2.27%     2.27%
Cash Flow Hedging [Member]        
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax $ (1,600) 200 (2,500)  
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]        
Derivative, Number of Instruments Held, Total 2     2
Derivative, Fixed Interest Rate 0.03%     0.03%
Derivative, Notional Amount $ 17,200     € 15
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | SEACOR Marine Foreign Holdings [Member]        
Derivative, Fixed Interest Rate 3.32%     3.32%
Derivative, Notional Amount $ 9,800      
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | SEACOR 88/888 [Member]        
Derivative, Fixed Interest Rate 3.50%     3.50%
Derivative, Notional Amount $ 5,500      
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | MexMar [Member]        
Derivative, Number of Instruments Held, Total 5     5
Derivative, Notional Amount $ 97,000      
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | MexMar [Member] | Minimum [Member]        
Derivative, Fixed Interest Rate 1.71%     1.71%
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | MexMar [Member] | Maximum [Member]        
Derivative, Fixed Interest Rate 2.10%     2.10%
Cash Flow Hedging [Member] | Interest Rate Swap 2 [Member] | Designated as Hedging Instrument [Member] | SEACOR Marine Foreign Holdings [Member]        
Derivative, Fixed Interest Rate 3.195%     3.195%
Derivative, Notional Amount $ 54,100      
Construction in Progress [Member] | Fair Value Hedging [Member]        
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge   $ 100 $ (800)