Impairment of Long-lived Assets (Details) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) TankBarge	Dec. 31, 2017 USD ($)
Long-lived Assets Impairment [Abstract]
Non-cash pre-tax impairment charge	$ 82,705	$ 105,712	$ 0	$ 82,705	$ 105,712
Impairment charge after tax effect	$ 65,337	$ 66,975
Impairment charge after tax effect on earning per share (in dollars per share) | $ / shares	$ 1.09	$ 1.20
Lease cancellation costs			$ 0	2,403	0
Vessels [Member]
Long-lived Assets Impairment [Abstract]
Non-cash pre-tax impairment charge	$ 78,835
Fair market value of assets	13,247	$ 12,550		13,247	$ 12,550
Tank Barge [Member]
Long-lived Assets Impairment [Abstract]
Non-cash pre-tax impairment charge				$ 3,870
Number of vessels to be disposed of | TankBarge				4
Fair market value of assets	220			$ 220
Scrap value of vessel	$ 220			220
Lease cancellation costs				$ 2,403