State and Local Incentives (Changes in Deferred Income from State Incentives) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
State and Local Incentives [Abstract]
Balance at the beginning of the year	$ 4,722	$ 6,941
Recognition of state and local incentives as a reduction of cost of sales	(2,215)	(2,219)
Balance at the end of the year, including current portion	$ 2,507	$ 4,722

Deferred income from government grants as of the balance sheet date. This liability represents the portion of government grants received which has not yet been recognized in the income statement.

No definition available.

Name:	rail_DeferredIncomeGovernmentGrants
Namespace Prefix:	rail_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant