Summary of significant accounting policies - Shipping and Handling Costs (Details) - USD ($)	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Accounting Policies [Abstract]
Shipping and handling expense	$ 1,381,070	$ 1,261,294

Selling, General and Administrative Expense, Shipping and Handling Costs

No definition available.

Name:	fgi_SellingGeneralAndAdministrativeExpenseShippingAndHandlingCosts
Namespace Prefix:	fgi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration