Significant Accounting Policies, Distinguishing Liabilities from Equity (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Distinguishing Liabilities from Equity [Abstract]
Warrants classified as liabilities	$ 0

Value of warrants classified as liabilities vs. equity.

No definition available.

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