Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts Receivable [Abstract]
Accruals for revenues earned included in accounts receivable	$ 114,159	$ 153,661
Receivables from insurance companies to cover claims in excess included in accounts receivable	$ 69,624	66,588
Drydocking on Ocean-Going Vessels [Abstract]
Period in which recertification of ocean going vessels occur twice	5 years
Recognized amortization of major maintenance costs	$ 20,760	21,207	$ 19,869
Capitalized interest excluded from interest expense	$ 2,206	$ 1,731	$ 2,974
Minimum [Member]
Drydocking on Ocean-Going Vessels [Abstract]
Period of amortization of shipyard costs	30 months
Maximum [Member]
Drydocking on Ocean-Going Vessels [Abstract]
Period of amortization of shipyard costs	60 months
Marine Transportation Equipment [Member] | Minimum [Member]
Property, Maintenance and Repairs [Abstract]
Estimated useful lives of the individual assets	5 years
Marine Transportation Equipment [Member] | Maximum [Member]
Property, Maintenance and Repairs [Abstract]
Estimated useful lives of the individual assets	40 years
Buildings [Member] | Minimum [Member]
Property, Maintenance and Repairs [Abstract]
Estimated useful lives of the individual assets	10 years
Buildings [Member] | Maximum [Member]
Property, Maintenance and Repairs [Abstract]
Estimated useful lives of the individual assets	40 years
Other Equipment [Member] | Minimum [Member]
Property, Maintenance and Repairs [Abstract]
Estimated useful lives of the individual assets	2 years
Other Equipment [Member] | Maximum [Member]
Property, Maintenance and Repairs [Abstract]
Estimated useful lives of the individual assets	10 years