Revenues (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Abstract]
Revenues by major source	$ 496,850,000	$ 643,926,000
Revenue recognized	30,753,000	32,386,000
Marine Transportation [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	300,951,000	403,257,000
Marine Transportation [Member] | Inland Transportation [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	224,451,000	318,565,000
Marine Transportation [Member] | Coastal Transportation [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	76,500,000	84,692,000
Distribution and Services [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	195,899,000	240,669,000
Distribution and Services [Member] | Commercial and Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	132,908,000	161,991,000
Distribution and Services [Member] | Oil and Gas [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	$ 62,991,000	$ 78,678,000