Fair Value of Financial Instruments (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2020
Jun. 30, 2020
Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]      
Impairment loss   $ 472  
Two vessels      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]      
Impairment loss $ 8,967    
Three vessels      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]      
Impairment loss     $ 92,013
Chartered-in vessels      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]      
Impairment loss     $ 38,636