Intangible Assets (Schedule of Components of Intangible Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 204,712	$ 196,834
Accumulated Amortization	77,511	69,771
Carrying Value	127,201	127,063
Contract intangibles | Marine Transportation [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	800	800
Accumulated Amortization	634	607
Carrying Value	166	193
Contract intangibles | Offshore pipeline transportation
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	158,101	158,101
Accumulated Amortization	59,635	53,394
Carrying Value	98,466	104,707
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	45,811	37,933
Accumulated Amortization	17,242	15,770
Carrying Value	$ 28,569	$ 22,163