Commitments and Contingencies - Additional Information (Details) R$ in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2025 USD ($) Vessel	Dec. 31, 2024 USD ($) Vessel	Sep. 30, 2025 USD ($) Vessel	Sep. 30, 2024 Vessel	Sep. 30, 2025 BRL (R$)
Commitments And Contingencies [Line Items]
Unrecorded unconditional purchase obligation, total			$ 54.5
Unrecorded unconditional purchase obligation, due in remainder of fiscal year			4.8
Unrecorded unconditional purchase obligation payable during 2026			$ 31.4
Deficiency Notice
Commitments And Contingencies [Line Items]
Cost allocation percentage			70.00%
Deficiency Notice \| Seabulk Overseas
Commitments And Contingencies [Line Items]
Cost allocation percentage			30.00%
2024 SMFH Credit Facility
Commitments And Contingencies [Line Items]
Maximum borrowing percentage of purchase price			50.00%		50.00%
2024 SMFH Credit Facility \| Tranche Two
Commitments And Contingencies [Line Items]
Line of credit facility, maximum borrowing capacity			$ 41.0
Line of credit facility, drawn			16.4
Minimum \| Deficiency Notice
Commitments And Contingencies [Line Items]
Potential range of levies			5.4		R$ 28,600
Maximum \| Deficiency Notice
Commitments And Contingencies [Line Items]
Potential range of levies			2.4		R$ 12,870
Platform Supply Vessels
Commitments And Contingencies [Line Items]
Unrecorded unconditional purchase obligation, total			$ 51.3
Number of equipment sold \| Vessel			2
Unrecorded unconditional purchase obligation, maximum quantity			2		2
Platform Supply Vessels \| 2024 SMFH Credit Facility
Commitments And Contingencies [Line Items]
Number of equipment sold \| Vessel	2
Proceeds from sale of productive assets	$ 10.9
Payments to acquire productive assets			$ 16.6
Unrecorded unconditional purchase obligation, maximum quantity			2		2
Hybrid Battery Power Systems
Commitments And Contingencies [Line Items]
Unrecorded unconditional purchase obligation, total			$ 2.0
Unrecorded unconditional purchase obligation, maximum quantity			4		4
Anchor Handling Towing Supply Vessel
Commitments And Contingencies [Line Items]
Number of equipment sold \| Vessel				1
Anchor Handling Towing Supply Vessel \| 2024 SMFH Credit Facility
Commitments And Contingencies [Line Items]
Number of equipment sold \| Vessel		2
Proceeds from sale of productive assets		$ 18.0
Fast Support Vessels \| 2024 SMFH Credit Facility
Commitments And Contingencies [Line Items]
Number of equipment sold \| Vessel	1
Proceeds from sale of productive assets	$ 3.8
Miscellaneous Vessel Equipment
Commitments And Contingencies [Line Items]
Unrecorded unconditional purchase obligation, total			$ 1.2

SEACOR Marine Holdings Inc. 10-Q