Investments, At Equity, And Advances To 50% Or Less Owned Companies (Narrative) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($) equipment vessel
U.S.-flag Offshore Tug
Schedule Of Equity Method Investments [Line Items]
Equipment Subject to Operating Lease, Number of Units | equipment	1
Inland River Towboats
Schedule Of Equity Method Investments [Line Items]
Equipment Subject to Operating Lease, Number of Units | equipment	4
Trailer Bridge | U.S.-flag Offshore Tug
Schedule Of Equity Method Investments [Line Items]
Equipment Subject to Operating Lease, Number of Units | vessel	1
RF Vessel Holdings
Schedule Of Equity Method Investments [Line Items]
Partners' Capital Account, Contributions	$ 4,400
Golfo de Mexico
Schedule Of Equity Method Investments [Line Items]
Partners' Capital Account, Contributions	$ 500
KSM | Foreign-flag Harbor Tugs
Schedule Of Equity Method Investments [Line Items]
Equipment Subject to Operating Lease, Number of Units | vessel	2
SCF Bunge Marine
Schedule Of Equity Method Investments [Line Items]
Proceeds from Equity Method Investment, Distribution	$ 1,300
SCF Bunge Marine | Inland River Towboats
Schedule Of Equity Method Investments [Line Items]
Equipment Subject to Operating Lease, Number of Units | vessel	8
Other Inland Services Equity Method Investments
Schedule Of Equity Method Investments [Line Items]
Proceeds from Equity Method Investment, Distribution	$ 200
O'Brien's do Brazil
Schedule Of Equity Method Investments [Line Items]
Proceeds from Equity Method Investment, Distribution	500
VA&E
Schedule Of Equity Method Investments [Line Items]
Payments for Advances and Loans to Affiliate	1,200
Proceeds from Collection of Advance to Affiliate	900
Time Charter | Trailer Bridge
Schedule Of Equity Method Investments [Line Items]
Revenue from Related Parties	3,100
Time Charter | SCF Bunge Marine
Schedule Of Equity Method Investments [Line Items]
Revenue from Related Parties	6,000
Bareboat Charter | KSM
Schedule Of Equity Method Investments [Line Items]
Revenue from Related Parties	1,200
Rental Income | Bunge SCF Grain
Schedule Of Equity Method Investments [Line Items]
Revenue from Related Parties	$ 500