Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments And Hedging Strategies (Narrative) (Details)

v3.7.0.1
Derivative Instruments And Hedging Strategies (Narrative) (Details)
$ in Thousands, € in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2017
USD ($)
Jun. 30, 2016
USD ($)
Jun. 30, 2017
USD ($)
Jun. 30, 2016
USD ($)
Jun. 30, 2017
EUR (€)
Derivative [Line Items]          
Derivative losses on cash flow hedges $ (429) $ (1,820) $ (438) $ (3,605)  
Fair Value Hedging [Member]          
Derivative [Line Items]          
Derivative, Notional Amount 1,900   1,900    
Cash Flow Hedging [Member]          
Derivative [Line Items]          
Derivative, Notional Amount $ 17,100   $ 17,100   € 15.0
Fixed interest rate 0.03%   0.03%   0.03%
Cash Flow Hedging [Member] | Mexmar [Member]          
Derivative [Line Items]          
Derivative, Notional Amount $ 117,200   $ 117,200    
Cash Flow Hedging [Member] | Sea-Cat Crewzer II [Member]          
Derivative [Line Items]          
Derivative, Notional Amount $ 22,100   $ 22,100    
Fixed interest rate 1.52%   1.52%   1.52%
Cash Flow Hedging [Member] | Sea Cat Crewzer [Member]          
Derivative [Line Items]          
Derivative, Notional Amount $ 19,600   $ 19,600    
Fixed interest rate 1.52%   1.52%   1.52%
Construction in Progress [Member]          
Derivative [Line Items]          
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge     $ 100    
Minimum [Member] | Cash Flow Hedging [Member] | Mexmar [Member]          
Derivative [Line Items]          
Fixed interest rate 1.71%   1.71%   1.71%
Maximum [Member] | Cash Flow Hedging [Member] | Mexmar [Member]          
Derivative [Line Items]          
Fixed interest rate 2.10%   2.10%   2.10%