Annual report pursuant to Section 13 and 15(d)

Note 1 - Nature of Operations and Accounting Policies (Details Textual)

v3.19.1
Note 1 - Nature of Operations and Accounting Policies (Details Textual)
$ in Thousands
12 Months Ended
Jan. 01, 2019
USD ($)
Jan. 01, 2018
USD ($)
Dec. 31, 2018
USD ($)
shares
Dec. 31, 2017
USD ($)
shares
Dec. 31, 2016
USD ($)
shares
Dec. 31, 2015
USD ($)
Number of Reportable Segments     5      
Contract with Customer, Liability, Total     $ 1,327 $ 10,104 $ 6,953 $ 6,953
Inventory Valuation Reserves, Ending Balance     200 0 0  
Depreciation, Total     72,200 62,800 58,000  
Capitalized Interest Costs, Including Allowance for Funds Used During Construction, Total     2,400 3,600 7,000  
Amortization of Intangible Assets, Total         100  
Impairment of Long-Lived Assets Held-for-use     14,600 27,500 119,700  
Equity Method Investment, Other than Temporary Impairment     $ 1,200 8,800 $ 6,900  
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount       $ 4,500    
Incremental Common Shares Attributable to Conversion of Debt Securities, Total | shares     2,183,708 4,070,500 4,070,500  
Accounting Standards Update 2016-02 [Member] | Subsequent Event [Member]            
Operating Lease, Right-of-Use Asset $ 33,900          
Operating Lease, Liability, Total 32,100          
Accounting Standards Update 2016-02 [Member] | Subsequent Event [Member] | Change in Accounting Principle for Equipment, Office and Land Leases [Member]            
Cumulative Effect on Retained Earnings, Net of Tax, Total 1,800          
Accounting Standards Update 2016-02 [Member] | Subsequent Event [Member] | Change in Accounting Principle for Unamortized Deferred Gains [Member]            
Cumulative Effect on Retained Earnings, Net of Tax, Total $ 8,700          
Accounting Standards Update 2016-16 [Member]            
Cumulative Effect on Retained Earnings, Net of Tax, Total   $ 12,100        
Restricted Stock [Member]            
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares     192,346 121,693    
Employee Stock Option [Member]            
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares     805,566 613,700    
Geographic Distribution, Domestic [Member]            
Contract with Customer, Liability, Total     $ 6,800      
Geographic Distribution, Foreign [Member]            
Contract with Customer, Liability, Total     $ 1,300      
MexMar [Member]            
Equity Method Investment, Ownership Percentage     49.00%      
MEXMAR Offshore [Member]            
Equity Method Investment, Ownership Percentage     49.00%      
Brazil, Mexico, Central and South America [Member]            
Number of Vessels     34      
Number of Vessels Owned     7      
Number of Vessels Joint Ventured     27      
Europe [Member]            
Number of Vessels     40      
Number of Vessels Owned     36      
Number of Vessels Joint Ventured     4