Research and Development, Net (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Research and Development Expense [Member]
Research and Development, Net (Details) [Line Items]
Share-based payment	$ 402	$ 531	$ 578

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

No definition available.

Name:	frsx_AllocatedShareBasedCompensationExpenses
Namespace Prefix:	frsx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration