Fair Value of Financial Instruments (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]      
Impairment loss $ 50,565 $ 0 $ 0
Loss on investments in Navios Partners and Navios Aqcuisition   $ 228,026  
One vessel      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]      
Impairment loss $ 32,930