Initial direct costs associated with finance lease.

No definition available.

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Namespace Prefix:	ship_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of cash outflow for prepayment of finance lease and other initial direct costs.

+ References

No definition available.

+ Details

Name:	ship_FinanceLeasePrepaymentsAndOtherInitialDirectCosts
Namespace Prefix:	ship_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Daily bareboat rate charged for the vessel to the lessee under a finance lease.

+ References

No definition available.

+ Details

Name:	ship_LesseeFinanceLeaseDailyBareboatRate
Namespace Prefix:	ship_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Purchase price of vessel at the end of the bareboat period by the lessee under a finance lease.

+ References

No definition available.

+ Details

Name:	ship_LesseeFinanceLeasePurchasePrice
Namespace Prefix:	ship_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of interest expense on finance lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 53
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479589/842-20-55-53

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-4

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-4

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Present value of lessee's discounted obligation for lease payments from finance lease, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-1

+ Details

Name:	us-gaap_FinanceLeaseLiabilityCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Indicates line item in statement of financial position that includes current finance lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-2

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	enum2:enumerationSetItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, after accumulated amortization, of right-of-use asset from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-1

+ Details

Name:	us-gaap_FinanceLeaseRightOfUseAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization expense attributable to right-of-use asset from finance lease.

+ References

+ Details

Name:	us-gaap_FinanceLeaseRightOfUseAssetAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_LesseeDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Discount rate used by lessee to determine present value of finance lease payments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

Name:	us-gaap_LesseeFinanceLeaseDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's finance lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

Name:	us-gaap_LesseeFinanceLeaseTermOfContract1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of acquisition of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_IncomeStatementLocationAxis=ship_DepreciationAndAmortizationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=ship_BlueshipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=ship_TitanshipMember
Namespace Prefix:
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Finance Lease, Right-of-use Assets and Finance Lease Liabilities (Details) - USD ($) $ in Thousands							12 Months Ended
	Aug. 25, 2025	Feb. 25, 2025	Jan. 23, 2025	Oct. 24, 2024	Oct. 24, 2023	May 09, 2023	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Finance Lease, Right-of-use Assets and Finance Lease Liabilities [Abstract]
Finance lease prepayments and other initial direct costs							$ 8,300	$ 610	$ 7,000
Interest expense on finance lease liability							518	898	219
Depreciation and Amortization [Member]
Finance Lease, Right-of-use Assets and Finance Lease Liabilities [Abstract]
Amortization of right-of use asset							$ 1,050	$ 1,150	$ 436
Blueship [Member]
Finance Lease, Right-of-use Assets and Finance Lease Liabilities [Abstract]
Term of bareboat charter agreement							6 months
Finance lease prepayments and other initial direct costs		$ 4,000	$ 4,000
Daily bareboat rate			10
Purchase price of vessel	$ 22,500		$ 22,500
Incremental borrowing rate		4.65%
Finance lease liability, current		$ 23,747
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]		Other current liabilities
Right-of-use asset		$ 32,381
Initial direct costs		$ 334
Addition to vessels, net	$ 31,009
Titanship [Member]
Finance Lease, Right-of-use Assets and Finance Lease Liabilities [Abstract]
Term of bareboat charter agreement							12 months
Finance lease prepayments and other initial direct costs					$ 3,500	$ 3,500
Daily bareboat rate						9
Purchase price of vessel				$ 20,210		$ 20,210
Incremental borrowing rate					5.40%
Finance lease liability, current					$ 22,388
Right-of-use asset					29,998
Initial direct costs					$ 610
Addition to vessels, net				$ 28,412