Investments in affiliates and investments in available-for-sale securities - Merger Agreement Navios Partners (Details) - shares
3 Months Ended
Mar. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Navios Europe I      
Investments In And Advances To Affiliates [Line Items]      
Percentage of ownership     47.50%
Navios Partners      
Investments In And Advances To Affiliates [Line Items]      
Percentage of ownership 12.60% 17.90%  
Navios Partners | Navios Partners Merger      
Investments In And Advances To Affiliates [Line Items]      
Business Acquisition, Name of Acquired Entity Navios Containers    
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares 8,133,452    
Exchange ratio 0.39    
Date of delivery Jan. 04, 2021    
Date of acquisition Mar. 31, 2021