NOTE I - FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Oct. 31, 2017	Apr. 30, 2017
NOTE I - FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Line Items]
Fair Value, Less than 12 months	$ 0	$ 219
Unrealized Losses, Less than 12 months	0	(9)
Fair Value, 12 Months or more	0	1,024
Unrealized Losses, 12 Months or more	0	(230)
Fair Value	0	1,243
Unrealized Losses	0	(239)
Fixed Income Securities [Member]
NOTE I - FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Line Items]
Fair Value, Less than 12 months	0	0
Unrealized Losses, Less than 12 months	0	0
Fair Value, 12 Months or more	0	0
Unrealized Losses, 12 Months or more	0	0
Fair Value	0	0
Unrealized Losses	0	0
Equity Securities [Member]
NOTE I - FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Line Items]
Fair Value, Less than 12 months	0	219
Unrealized Losses, Less than 12 months	0	(9)
Fair Value, 12 Months or more	0	1,024
Unrealized Losses, 12 Months or more	0	(230)
Fair Value	0	1,243
Unrealized Losses	$ 0	$ (239)

No definition available.

Name:	feim_NOTEIFAIRVALUEOFFINANCIALINSTRUMENTSDetailsAvailableforsaleSecuritiesContinuousUnrealizedLossPositionFairValueLineItems
Namespace Prefix:	feim_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unrealized loss on securities classified as available-for-sale that have been in a loss position for twelve months or longer.

+ References

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of unrealized loss on securities classified as available-for-sale.

+ References

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

+ References

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of unrealized loss on investments in available-for-sale securities that have been in a loss position for less than twelve months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_FixedIncomeSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: