Other Current Assets, Properties and Equipment, Other Assets, Accrued Expenses, Other Current Liabilities and Other Liabilities - Additional Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Dec. 31, 2019 USD ($) Vessel	Sep. 30, 2019 USD ($) Vessel	Sep. 30, 2018 USD ($)
Property Plant And Equipment [Line Items]
Number of vessels		220
Proceeds from sales of assets | $		$ 25,092	$ 16,499
Scenario, Forecast
Property Plant And Equipment [Line Items]
Number of vessels sold	2
Proceeds from sales of assets | $	$ 3,600
Americas | Scenario, Forecast
Property Plant And Equipment [Line Items]
Number of vessels sold	1
West Africa | Scenario, Forecast
Property Plant And Equipment [Line Items]
Number of vessels sold	1