Annual report pursuant to Section 13 and 15(d)

Note 6 - Leases (Details Textual)

v3.19.1
Note 6 - Leases (Details Textual)
$ in Thousands
12 Months Ended
Jan. 01, 2019
USD ($)
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Number of Vessels Leased   8    
Operating Leases, Rent Expense, Net, Total   $ 13,300 $ 14,500 $ 19,400
Operating Lease, Impairment Loss   $ 6,800 $ 5,400  
Number of Operating Leases Impaired   3 1  
Subsequent Event [Member] | Accounting Standards Update 2016-02 [Member]        
Operating Lease, Right-of-Use Asset $ 33,900      
Operating Lease, Liability, Total 32,100      
Subsequent Event [Member] | Accounting Standards Update 2016-02 [Member] | Change in Accounting Principle for Equipment, Office and Land Leases [Member]        
Cumulative Effect on Retained Earnings, Net of Tax, Total 1,800      
Subsequent Event [Member] | Accounting Standards Update 2016-02 [Member] | Change in Accounting Principle for Unamortized Deferred Gains [Member]        
Cumulative Effect on Retained Earnings, Net of Tax, Total $ 8,700      
Minimum [Member]        
Lessee, Operating Lease, Term of Contract   1 year    
Maximum [Member]        
Lessee, Operating Lease, Term of Contract   3 years