Intangible Assets, Goodwill and Other Assets (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 188,145	$ 220,192
Accumulated Amortization		59,403	81,265
Carrying Value		$ 128,742	138,927
Other
Finite-Lived Intangible Assets [Line Items]
Weighted Amortization Period in Years		9 years
Gross Carrying Amount		$ 29,244	34,291
Accumulated Amortization		13,759	21,480
Carrying Value		$ 15,485	12,811
Marine transportation
Finite-Lived Intangible Assets [Line Items]
Weighted Amortization Period in Years	[1]	20 years
Marine transportation | Contract intangible
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	[1]	$ 800	27,800
Accumulated Amortization	[1]	571	23,033
Carrying Value	[1]	$ 229	4,767
Offshore pipeline transportation
Finite-Lived Intangible Assets [Line Items]
Weighted Amortization Period in Years		19 years
Offshore pipeline transportation | Contract intangible
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 158,101	158,101
Accumulated Amortization		45,073	36,752
Carrying Value		$ 113,028	$ 121,349

[1] The marine contract intangible associated with the M/T American Phoenix became fully amortized and retired as of September 30, 2020