Amount of cash paid for deposits under sale and leaseback agreements.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

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

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

+ Details

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Balance Type:	credit
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- Definition

Term of charter on a bareboat basis under the sale leaseback transaction, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- Definition

Amount of cash payment made to the owner under the sale leaseback agreement upon the delivery of the vessel.

+ References

No definition available.

+ Details

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

- Definition

The minimum threshold value maintenance ratio (expressed as a percentage) as defined in the additional clauses of the bareboat charter to be maintained by the Company.

+ References

No definition available.

+ Details

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- 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_
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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://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Balance Type:	credit
Period Type:	instant

- Definition

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

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments applied to principal.

+ References

+ Details

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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

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
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- Definition

Minimum amount of purchase arrangement in which the entity has agreed to expend funds to procure goods or services from a supplier.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

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- Details

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Long-Term Debt and Other Financial Liabilities, Hanchen Sale and Leaseback (Details) $ in Thousands			12 Months Ended
	Mar. 29, 2023 USD ($) Installment	Jun. 28, 2018 USD ($)	Dec. 31, 2022 USD ($) Installment	Dec. 31, 2021 USD ($)
Sale and Leaseback Transaction [Abstract]
Balance outstanding			$ 235,603	$ 218,551
Hanchen Sale and Leaseback [Member]
Sale and Leaseback Transaction [Abstract]
Face amount		$ 26,500
Term of charter contract			8 years
Proceeds from sale of vessel		18,550
Upfront charterhire payment		6,625
Deposit made under sale and leaseback agreement		1,325
Minimum value maintenance ratio to be maintained			1.20
Purchase obligation		$ 5,299
Number of consecutive payment installments \| Installment			32
Frequency of periodic payment			quarterly
Installment payment			$ 456
Balloon payment			$ 5,299
Maturity date			Jun. 29, 2026
Balance outstanding			$ 11,676
Hanchen Sale and Leaseback [Member] \| LIBOR [Member]
Sale and Leaseback Transaction [Abstract]
Margin on variable rate			4.00%
Evahline Sale and Leaseback [Member] \| Subsequent Event [Member]
Sale and Leaseback Transaction [Abstract]
Face amount	$ 19,000
Number of consecutive payment installments \| Installment	72
Installment payment	$ 264