Note 7 - Components of Working Capital Accounts (Details Textual) $ in Thousands	Dec. 31, 2024 USD ($)
Other Liabilities [Member]
Value Appreciation Plans	$ 75,006

Represents the amount of value appreciation plans.

No definition available.

Name:	fsv_ValueAppreciationPlans
Namespace Prefix:	fsv_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant