Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Abstract]
Revenues by major source	$ 2,970,697	$ 2,214,418	$ 1,770,673
Revenue recognized	43,348
Marine Transportation [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	1,483,143	1,324,106	1,471,893
Marine Transportation [Member] | Inland Transportation [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	1,119,820	923,916	951,097
Marine Transportation [Member] | Coastal Transportation [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	363,323	400,190	520,796
Distribution and Services [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	1,487,554	890,312	298,780
Distribution and Services [Member] | Oil and Gas [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	1,010,410	614,128	115,012
Distribution and Services [Member] | Commercial and Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	$ 477,144	$ 276,184	$ 183,768