Amount of additional Repayment (as defined in the Loan Agreement) that was waived.

No definition available.

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

- Definition

Amount of fees incurred in connection with an amendment or modification to any provision of a debt instrument during the period.

+ References

No definition available.

+ Details

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

- 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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Namespace Prefix:	ship_
Data Type:	xbrli:integerItemType
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- Definition

Amount of repayment of certain subordinated liabilities (as defined in the Loan Agreement).

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480848/942-470-50-3

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-SubTopic 10
-Topic 210
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

+ Details

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Namespace Prefix:	us-gaap_
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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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

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

- Definition

The cash outflow to repay long-term debt that is wholly or partially secured by collateral. Excludes repayments of tax exempt secured debt.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-15

+ Details

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

- References

No definition available.

+ Details

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

- Details

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Namespace Prefix:
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Period Type:

- Details

Name:	us-gaap_VariableRateAxis=ship_LondonInterbankOfferedRateMember
Namespace Prefix:
Data Type:	na
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- Details

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Long-Term Debt and Other Financial Liabilities, February 2019 ATB Loan Facility (Details)			12 Months Ended
	Feb. 28, 2022 USD ($)	Dec. 09, 2021 USD ($)	Dec. 31, 2023 USD ($) Installment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Senior Long-Term Debt [Abstract]
Repayment of long-term debt			$ 88,742,000	$ 89,698,000	$ 132,058,000
February 2019 ATB Loan Facility [Member]
Senior Long-Term Debt [Abstract]
Repayment of certain subordinated liabilities		$ 1,080,000
Additional repayment waived		1,080,000
Amendment fee		$ 50,000
Repayment of long-term debt	$ 15,129,000
February 2019 ATB Loan Facility [Member] \| LIBOR [Member]
Senior Long-Term Debt [Abstract]
Margin on variable rate			4.65%
Tranche A [Member]
Senior Long-Term Debt [Abstract]
Number of consecutive payment installments \| Installment			16
Frequency of periodic payment			quarterly
Installment payment			$ 200,000
Balloon payment			$ 13,190,000
Tranche B [Member]
Senior Long-Term Debt [Abstract]
Number of consecutive payment installments \| Installment			12
Frequency of periodic payment			quarterly
Installment payment			$ 189,800
Maturity date			Aug. 26, 2022
Tranche C [Member]
Senior Long-Term Debt [Abstract]
Number of consecutive payment installments \| Installment			12
Frequency of periodic payment			quarterly
Installment payment			$ 189,800
Maturity date			Aug. 26, 2022