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

The carrying amount of minimum liquidity requirement to be maintained in an earnings account by the borrower under the loan agreement.

No definition available.

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

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

No definition available.

Name:	ship_DebtInstrumentNumberOfConsecutivePaymentInstallments
Namespace Prefix:	ship_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The number of tranches the advance is available to be drawn down under the loan.

No definition available.

Name:	ship_DebtInstrumentNumberOfTranches
Namespace Prefix:	ship_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

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.

No definition available.

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

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

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

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.

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

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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

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

Incremental percentage increase (decrease) in the stated rate on a debt instrument.

No definition available.

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

Amount of the required periodic payments applied to principal.

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

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

No definition available.

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

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

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

- References

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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Period Type:	duration

Name:	us-gaap_DebtInstrumentAxis=ship_October2022DanishShipFinanceLoanFacilityMember
Namespace Prefix:
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Balance Type:
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Name:	us-gaap_VariableRateAxis=us-gaap_SecuredOvernightFinancingRateSofrMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=ship_DebtInstrumentRedemptionFirstSixInstallmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=ship_DebtInstrumentRedemptionLastFourteenInstallmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_DebtInstrumentAxis=ship_NewTrancheSecuredByChampionshipMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_VariableRateAxis=ship_TermSecuredOvernightFinancingRateSofrMember
Namespace Prefix:
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