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Financing agreement.

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Percentage of gain from equity earnings.

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Return of capital equity method investment.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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Amount paid to managing member or general partner for management of the day-to-day business functions of the limited liability company (LLC) or limited partnership (LP).

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Amount of distribution received from equity method investee for return of investment, classified as investing activities. Excludes distribution for return on investment, classified as operating activities.

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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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Investments, at Equity, and Advances to 50% or Less Owned Companies - Additional Information (Details)							12 Months Ended
	Dec. 10, 2021 USD ($)	Dec. 09, 2021 USD ($)	Jul. 23, 2021 USD ($) Vessel	Jun. 01, 2021 USD ($) Vessel	Dec. 28, 2018 USD ($)	Sep. 13, 2018 USD ($)	Dec. 31, 2021 USD ($) Vessel	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) Equipment	Dec. 20, 2018
Schedule Of Investments [Line Items]
Consolidated retained earnings							$ 38,700,000
Capital distributions from equity investees							$ 9,442,000
Equity method investment, ownership percentage			50.00%	50.00%						49.00%
Maximum
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage							50.00%	50.00%
Minimum [Member]
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage							20.00%
Mexmar Offshore International
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage				49.00%
Noncontrolling interest, ownership percentage by noncontrolling owners				51.00%						51.00%
Mexmar Offshore International \| UP Offshore
Schedule Of Investments [Line Items]
Purchase price				$ 30,200,000
Percentage of gain from equity earnings				50.00%
Gain on equity earnings				$ 2,600,000
MEXMAR Offshore
Schedule Of Investments [Line Items]
Gain on equity earnings			$ 2,600,000
Received distribution from joint ventures			12,000,000.0
Aggregate purchase price			$ 9,400,000
Number of vessels owned \| Vessel			3
Number of vessels joint ventured \| Vessel			2
Transferred equity interest		49.00%
Equity interest transferred consideration and transaction fee.		$ 200,000
Offshore Vessel Holdings
Schedule Of Investments [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners					51.00%
Noncontrolling Interest, ownership percentage by parent					49.00%
Payments to acquire interest in joint venture					$ 4,900,000
Contributed capital									$ 10,000,000.0
Financing agreement									$ 2,400,000
Management fees							$ 1,000,000.0
OVH and OPEM
Schedule Of Investments [Line Items]
Settled loan	$ 10,000,000.0
Early repayment of debt	10,500,000
Forgiveness of accrued interest	$ 4,100,000
Offshore Support Vessels, Supply \| Mexmar Offshore International
Schedule Of Investments [Line Items]
Number of vessels sold \| Vessel				8
Offshore Support Vessels, Supply \| Offshore Vessel Holdings
Schedule Of Investments [Line Items]
Number of equipment operated \| Equipment									3
Jack up Drillings [Member] \| Offshore Vessel Holdings
Schedule Of Investments [Line Items]
Number of equipment operated \| Equipment									2
F S V Offshore Support Vessels \| Offshore Vessel Holdings
Schedule Of Investments [Line Items]
Number of equipment operated \| Equipment									1
MexMar
Schedule Of Investments [Line Items]
Capital distributions from equity investees							0	$ 0	$ 0
Revenue from related parties							$ 300,000	300,000	300,000
Equity method investment, ownership percentage							49.00%
Number of vessels owned \| Vessel							16
MexMar \| Offshore Support Vessels
Schedule Of Investments [Line Items]
Number of equipment operated \| Vessel							16
SEACOR Marlin LLC
Schedule Of Investments [Line Items]
Capital distributions from equity investees							$ 2,500,000	0	0
Equity method investment, ownership, percent sold						51.00%
Proceeds from divestiture of interest in joint venture						$ 8,000,000.0
Gain (loss) on disposition of business						$ 400,000
Equity method investment, ownership percentage							49.00%
Other Offshore Marine Services Joint Ventures
Schedule Of Investments [Line Items]
Number of equipment operated \| Vessel							0
Capital distributions from equity investees							$ 2,000,000.0	2,100,000	2,100,000
Revenue from related parties							$ 0	$ 0
Return of capital equity method investment									500,000
Other Offshore Marine Services Joint Ventures \| Maximum
Schedule Of Investments [Line Items]
Revenue from related parties									$ 100,000
Equity method investment, ownership percentage							50.00%
Other Offshore Marine Services Joint Ventures \| Minimum [Member]
Schedule Of Investments [Line Items]
Equity method investment, ownership percentage							20.00%