Note 4 - Loans Receivable and Related Allowance for Loan Losses - Impaired Loans by Class (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Impaired loans with specific allowance, unpaid principal balance	$ 270	$ 141	$ 76
Impaired loans with specific allowance, recorded investment	270	141	76
Related allowance	26	70	5
Impaired loans with specific allowance, average recorded investment	173	110	77
Impaired loans with specific allowance, interest income recognized in period	2	1	3
Impaired loans with specific allowance, cash basis interest recognized in period	2	1	3
Impaired loans with no specific allowance, unpaid principal balance	1,500	454	519
Impaired loans with no specific allowance, recorded investment	1,388	379	407
Impaired loans with no specific allowance, average recorded investment	897	383	1,399
Impaired loans with no specific allowance, interest income recognized in period	15	3	99
Impaired loans with no specific allowance, cash basis interest recognized in period	14	3	41
Residential Portfolio Segment [Member]
Impaired loans with specific allowance, unpaid principal balance	71	73	72
Impaired loans with specific allowance, recorded investment	71	73	72
Related allowance	2	7	5
Impaired loans with specific allowance, average recorded investment	71	73	72
Impaired loans with specific allowance, interest income recognized in period	1	1	3
Impaired loans with specific allowance, cash basis interest recognized in period	1	1	3
Impaired loans with no specific allowance, unpaid principal balance	390	382	398
Impaired loans with no specific allowance, recorded investment	278	307	286
Impaired loans with no specific allowance, average recorded investment	282	311	301
Impaired loans with no specific allowance, interest income recognized in period	1	1	4
Impaired loans with no specific allowance, cash basis interest recognized in period	1	1	4
Home Equity Loans and Lines of Credit [Member]
Impaired loans with specific allowance, unpaid principal balance	4	5	4
Impaired loans with specific allowance, recorded investment	4	5	4
Related allowance
Impaired loans with specific allowance, average recorded investment	4	6	5
Impaired loans with specific allowance, interest income recognized in period
Impaired loans with specific allowance, cash basis interest recognized in period
Impaired loans with no specific allowance, unpaid principal balance
Impaired loans with no specific allowance, recorded investment
Impaired loans with no specific allowance, average recorded investment
Impaired loans with no specific allowance, interest income recognized in period
Impaired loans with no specific allowance, cash basis interest recognized in period
Commercial Real Estate Portfolio Segment [Member]
Impaired loans with specific allowance, unpaid principal balance	150
Impaired loans with specific allowance, recorded investment	150
Related allowance	19
Impaired loans with specific allowance, average recorded investment	75
Impaired loans with specific allowance, interest income recognized in period
Impaired loans with specific allowance, cash basis interest recognized in period
Impaired loans with no specific allowance, unpaid principal balance	1,067	32	81
Impaired loans with no specific allowance, recorded investment	1,067	32	81
Impaired loans with no specific allowance, average recorded investment	574	33	1,019
Impaired loans with no specific allowance, interest income recognized in period	13	1	88
Impaired loans with no specific allowance, cash basis interest recognized in period	13	1	35
Commercial Portfolio Segment [Member]
Impaired loans with specific allowance, unpaid principal balance	45	63
Impaired loans with specific allowance, recorded investment	45	63
Related allowance	5	63
Impaired loans with specific allowance, average recorded investment	23	31
Impaired loans with specific allowance, interest income recognized in period	1
Impaired loans with specific allowance, cash basis interest recognized in period	1
Impaired loans with no specific allowance, unpaid principal balance	43	40	40
Impaired loans with no specific allowance, recorded investment	43	40	40
Impaired loans with no specific allowance, average recorded investment	41	39	79
Impaired loans with no specific allowance, interest income recognized in period	1	1	7
Impaired loans with no specific allowance, cash basis interest recognized in period		1	2
Consumer Portfolio Segment [Member]
Impaired loans with specific allowance, unpaid principal balance
Impaired loans with specific allowance, recorded investment
Related allowance
Impaired loans with specific allowance, average recorded investment
Impaired loans with specific allowance, interest income recognized in period
Impaired loans with specific allowance, cash basis interest recognized in period
Impaired loans with no specific allowance, unpaid principal balance
Impaired loans with no specific allowance, recorded investment
Impaired loans with no specific allowance, average recorded investment
Impaired loans with no specific allowance, interest income recognized in period
Impaired loans with no specific allowance, cash basis interest recognized in period

Amount of allowance for credit losses related to recorded investment.

Name:	us-gaap_ImpairedFinancingReceivableRelatedAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of average investment of impaired financing receivables for which there is no related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5258-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

+ Details

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

- Definition

Amount of interest income, recognized on accrual basis, on financing receivables that are recognized as impaired, for which there is no related allowance for credit losses.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of interest income, recognized on cash basis, on financing receivables, for which there is no related allowance for credit losses and are recognized as impaired.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953550-111524

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5258-111524

+ Details

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

- Definition

Amount of interest income, recognized on accrual basis, on financing receivables, for which there is a related allowance for credit losses and are recognized as impaired.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of interest income on financing receivables, for which there is a related allowance for credit losses, recognized on a cash-basis method of accounting that the financing receivables were impaired.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Definition

Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=emcf_HomeEquityLoansAndLinesOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: