XML 109 R64.htm IDEA: XBRL DOCUMENT v3.20.1
Financial risk management, objectives and policies, The ABN AMRO Revolving Credit Facility (Details) - USD ($)
$ in Thousands
 1 Months Ended 12 Months Ended
Jul. 31, 2018
Jun. 30, 2019
Dec. 31, 2019
Dec. 31, 2018
Apr. 30, 2018
Nov. 30, 2016
Credit Facility [Abstract]            
Borrowing amount     $ 850,972 $ 967,275    
Frequency of periodic repayment     Quarterly      
ABN AMRO Revolving Credit Facility [Member]            
Credit Facility [Abstract]            
Term     5 years      
Maximum borrowing capacity         $ 57,300 $ 50,000
Borrowing amount     $ 0      
Frequency of periodic repayment     Quarterly      
Reduction amount in credit facility $ 1,800 $ 1,300        
Credit facility covenant to maintain adjusted tangible net worth     $ 300,000      
ABN AMRO Revolving Credit Facility [Member] | Bottom of Range [Member]            
Credit Facility [Abstract]            
Covenants requiring all times charter-free market value of vessels     135.00%      
Percentage of covenant to maintain adjusted tangible net worth to total assets for credit facility     25.00%      
Credit facility covenant to maintain encumbered cash     $ 30,000      
Percentage of covenant required unencumbered consolidated cash to gross interest-bearing debt for credit facility     6.00%      
ABN AMRO Revolving Credit Facility [Member] | LIBOR [Member]            
Credit Facility [Abstract]            
Adjustment to interest rate basis     2.50%     2.50%