The number of consecutive, periodic payment installments in which the debt is to be repaid.

No definition available.

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Namespace Prefix:	ship_
Data Type:	xbrli:integerItemType
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Period Type:	duration

- Definition

Term of the interest rate that fluctuates over time as a result of an underlying benchmark interest rate or index, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	ship_DebtInstrumentTermOfVariableRate
Namespace Prefix:	ship_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Face amount of financial liability at time of sale and leaseback agreement.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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Namespace Prefix:	ship_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-SubTopic 10
-Topic 210
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-4

+ Details

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

- Definition

Description of the frequency of periodic payments (monthly, quarterly, annual).

+ References

+ Details

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

- Definition

Amount of the required periodic payments applied to principal.

+ References

+ Details

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

- Definition

Amount of payment greater than the preceding installment payments to be paid at final maturity date of debt.

+ References

No definition available.

+ Details

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

- Definition

Indicates type of variable interest rate on debt instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 470
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477734/942-470-50-3

+ Details

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

- Definition

Lease term for sale and leaseback transaction, 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 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479741/842-40-50-2

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DebtInstrumentAxis=ship_SquireshipHuarongSaleAndLeasebackAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Long-Term Debt and Other Financial Liabilities, Huarong Squireship Sale and Leaseback (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2025 USD ($) Installment	Mar. 13, 2025 USD ($)	Dec. 31, 2024 USD ($)
Sale and Leaseback Transaction [Abstract]
Balance outstanding	$ 289,237		$ 261,451
Huarong Squireship Sale and Leaseback [Member]
Sale and Leaseback Transaction [Abstract]
Financing amount		$ 18,000
Term of charter contract	5 years
Number of payment installments \| Installment	20
Frequency of periodic payment	quarterly
Installment payment	$ 475
Balloon payment	$ 8,500
Term of variable rate	3 months
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]	ship:TermSecuredOvernightFinancingRateSofrMember
Margin on variable rate	2.15%
Balance outstanding	$ 17,525