Note 5 - Loans Receivable, Net (Details Textual) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Receivable Loans and Leases, Commitments to Originate or Purchase Loans	$ 23,596	$ 38,157
Loans and Leases Receivable, Related Parties, Ending Balance	200	100	$ 100
Servicing Liability for Others, Unpaid Principal Balance	580,000	505,700	480,600
Fixed Rate Loans [Member]
Receivable Loans and Leases, Commitments to Originate or Purchase Loans	$ 19,500	$ 19,000
Fixed Rate Loans [Member] \| Minimum [Member]
Receivable Loans and Leases, Commitments Interest Percentage	2.25%	3.00%
Fixed Rate Loans [Member] \| Maximum [Member]
Receivable Loans and Leases, Commitments Interest Percentage	4.75%	5.65%
Loans to Executive Officers [Member]
Loans and Leases Receivable, Related Parties, Additions	$ 100
Loans and Leases Receivable, Related Parties, Proceeds	0
Loans to Executive Officers [Member] \| Consumer Portfolio Segment [Member] \| Home Equity Line [Member]
Loans and Leases Receivable, Related Parties, Ending Balance	100	$ 100	100
Loans and Leases Receivable, Related Parties, Proceeds	$ 0	$ 0	$ 0

Interest rates on fixed rate loans included in total commitments to originate or purchase loans.

No definition available.

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Namespace Prefix:	hmnf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Value of fixed rate loans included in total commitments to originate or purchase loans.

+ References

No definition available.

+ Details

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Namespace Prefix:	hmnf_
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Balance Type:	debit
Period Type:	instant

- Definition

Value of the unpaid principal balances for the liability for loans serviced for others.

+ References

No definition available.

+ Details

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Namespace Prefix:	hmnf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

For an unclassified balance sheet, reflects the carrying amount of unpaid loan amounts due from related parties at the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(e))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

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

- Definition

Reflects the amount of new advances made to related parties in the form of loan and lease receivables.

+ References

+ Details

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

- Definition

Amount of cash inflow from related parties which reduce the amount of loans and leases receivable due from related parties.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(7)(e)(1)(i))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Details

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- Details

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- Details

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