Derivative Instruments - Foreign Currency Loss (Details) - USD ($) $ in Thousands	3 Months Ended
Apr. 03, 2016	Mar. 29, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gain (Loss) Attributable To Foreign Exchange Rate Fluctuations, Inclusive Of The Impact Of Derivatives	$ (776)	$ (120)

Gain (Loss) Attributable To Foreign Exchange Rate Fluctuations, Inclusive Of The Impact Of Derivatives

No definition available.

Name:	feic_GainLossAttributableToForeignExchangeRateFluctuationsInclusiveOfTheImpactOfDerivatives
Namespace Prefix:	feic_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration