Investments in affiliates and investments in available-for-sale securities - Navios Europe I and Navios Europe II (Details)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2017
USD ($)
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 18, 2013
USD ($)
Feb. 18, 2015
USD ($)
Investments In And Advances To Affiliates [Line Items]              
Long-term debt   $ 1,816,007 $ 1,682,488 $ 1,651,095      
Investents in affiliates including accrued interest   29,328          
Portion of the carrying balance of related party loan   46,089 30,112        
Equity in net earnings of affiliated companies   (80,205) 4,399 (202,779)      
Investments in affiliates   91,111 183,160 160,071      
Navios Europe I              
Investments In And Advances To Affiliates [Line Items]              
Number of vessels acquired           10  
Difference between carrying amount of investment and underlying equity in net assets of equity method investee   3,357 4,034     $ 6,763  
Estimated maximum potential loss   $ 35,069 23,838        
Profit Sharing Arrangement   On an ongoing basis, Navios Europe I is required to distribute cash flows (after payment of operating expenses and amounts due pursuant to the terms of the Senior Loans I) according to a defined waterfall calculation.          
Equity in net earnings of affiliated companies   $ 0 (1,089) 1,303      
Investments in affiliates   4,750 4,750     4,750  
Navios Europe I | Navios Term Loans I              
Investments In And Advances To Affiliates [Line Items]              
Investents in affiliates including accrued interest   8,994 7,924        
Navios Europe I | Navios Revolving Loans I              
Investments In And Advances To Affiliates [Line Items]              
Portion of the carrying balance of related party loan   26,075 15,914        
Navios Europe I | Navios Revolving Loans I | Navios Holdings, Navios Acquisition and Navios Partners              
Investments In And Advances To Affiliates [Line Items]              
Line of credit facility maximum borrowing capacity           24,100  
Line of Credit Facility, Increase   30,000          
Navios Europe I | 10 vessels | Navios Holdings, Navios Acquisition and Navios Partners              
Investments In And Advances To Affiliates [Line Items]              
Long-term debt           $ 10,000  
Navios Europe II              
Investments In And Advances To Affiliates [Line Items]              
Number of vessels acquired         14    
Difference between carrying amount of investment and underlying equity in net assets of equity method investee   6,069 7,011       $ 9,419
Estimated maximum potential loss   $ 29,370 22,463        
Profit Sharing Arrangement   On an ongoing basis, Navios Europe II is required to distribute cash flows (after payment of operating expenses, amounts due pursuant to the terms of the Senior Loans II) according to a defined waterfall calculation.          
Equity in net earnings of affiliated companies   $ 2,032 2,456 $ (14)      
Investments in affiliates   6,650 6,650       $ 6,650
Navios Europe II | Navios Term Loans II              
Investments In And Advances To Affiliates [Line Items]              
Investents in affiliates including accrued interest   12,432 10,400        
Navios Europe II | Navios Revolving Loans II              
Investments In And Advances To Affiliates [Line Items]              
Portion of the carrying balance of related party loan   $ 16,938 $ 12,063        
Navios Europe II | Navios Revolving Loans II | Navios Holdings, Navios Acquisition and Navios Partners              
Investments In And Advances To Affiliates [Line Items]              
Line of credit facility maximum borrowing capacity         $ 43,500    
Line of Credit Facility, Increase $ 14,000            
Navios Europe II | 14 Vessels | Navios Holdings, Navios Acquisition and Navios Partners              
Investments In And Advances To Affiliates [Line Items]              
Long-term debt         $ 14,000