State and Local Incentives (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
Dec. 31, 2016	Dec. 31, 2021	Dec. 31, 2015
State and Local Incentives [Abstract]
State incentives received during the year	$ 1,410		$ 15,733
Incentive Agreement, Term		6 years

Amount of deferred income recognized for government grants arising during the current reporting period.Deferred income government grants is a liability as of the balance sheet date.

No definition available.

Name:	rail_DeferredIncomeGovernmentGrantsAdditions
Namespace Prefix:	rail_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration