Intangible Assets/Liabilities Other Than Goodwill - Additional Details (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended 11 Months Ended 12 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 15, 2014
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Intangible asset $ 112,288   $ 112,288     $ 116,422 $ 126,815    
Acquisition cost 190,212 [1]   190,212 [1]     200,610      
Accumulated amortization 77,924   77,924     73,790      
Write off 0   0     10,398      
Amortization of intangible assets 1,400 $ 1,775 4,134 $ 5,220          
Favorable lease terms                  
Intangible asset $ 1,150   $ 1,150     1,150 1,180    
Acquisition cost           10,398 70,937    
Accumulated amortization           7,001 57,930    
Gain / (loss) resulting from favorable lease terms written off           $ (3,397) (13,007)    
Unfavorable lease terms                  
Unfavorable lease terms             0    
Acquisition cost             24,721    
Accumulated amortization             17,406    
Gain / (loss) resulting from favorable lease terms written off             $ 7,315    
Two Companies | Navios Logistics                  
Date of acquisition           Dec. 15, 2014      
Total consideration         $ 17,000        
Deferred Payment For Acquisition Intangible Assets               $ 6,800 $ 10,200
[1] As of both September 30, 2018 and December 31, 2017, intangible assets associated with the favorable lease terms included an amount of $1,150 related to purchase options for the vessels.