The annual percentage inflation adjustment to monthly rent paid by the lessee under the operating lease.

No definition available.

Name:	ship_LeaseOperatingLeaseAnnualPercentageInflationAdjustment
Namespace Prefix:	ship_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease due after fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

Commitments and Contingencies (Details) $ in Thousands	1 Months Ended		12 Months Ended
Commitments and Contingencies (Details) $ in Thousands	Apr. 30, 2018 USD ($)	Apr. 30, 2018 EUR (€)	Dec. 31, 2021 USD ($) $ / €	Dec. 31, 2021 EUR (€)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 16, 2020 Extension
Future Minimum Contractual Charter Revenue [Abstract]
2022			$ 106,394
2023			20,800
2024			15,097
2025			15,056
2026			5,321
Total			162,668
Office Lease [Abstract]
Lease term of new office spaces	5 years	5 years					10 years
Number of extensions \| Extension							2
Renewal term of new office spaces	5 years	5 years					5 years
Monthly rent	$ 15	€ 13,000	$ 14	€ 12,747
Exchange rate \| $ / €			1.1326
Annual percentage inflation adjustment	1.00%	1.00%
Rent expense			$ 179		$ 180	$ 175
Office Rental Obligations [Abstract]
2022			136
2023			136
2024			136
2025			136
Thereafter			306
Total			850
Less: imputed interest			(200)
Present value of lease liabilities			650
Lease liabilities, current			121		140
Lease liabilities, non-current			$ 529		$ 705
Minimum [Member]
Commitments and Contingencies [Abstract]
Term of time charter agreements			9 months
Renewal term of time charter agreements			11 months
Maximum [Member]
Commitments and Contingencies [Abstract]
Term of time charter agreements			60 months
Renewal term of time charter agreements			27 months