Accounting for Certain Loans Acquired in a Transfer (Schedule of Acquired Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Total loans receivable	$ 1,496,207	$ 1,497,256	$ 1,467,746
Universal Bancorp [Member]
Loans acquired	163,252	179,968
Carrying amount, gross	161,002	177,169
Allowance	(161,002)	(177,169)
Carrying amount net of allowance	161,002	177,169
Commercial Real Estate [Member]
Total loans receivable	498,992	485,808
Real estate [Member]
Total loans receivable	1,054,841	1,080,729
Real estate [Member] \| Universal Bancorp [Member]
Loans acquired	152,357	167,639
Real estate [Member] \| Commercial Real Estate [Member] \| Universal Bancorp [Member]
Loans acquired	107,330	120,249
Other [Member]
Total loans receivable	441,366	416,527
Other [Member] \| Universal Bancorp [Member]
Loans acquired	10,895	12,329
Construction Loans [Member] \| Commercial Segment [Member]
Total loans receivable	59,072	53,310
Construction Loans [Member] \| Real estate [Member] \| Commercial Segment [Member] \| Universal Bancorp [Member]
Loans acquired	10,447	8,664
First Mortgage [Member] \| Consumer [Member]
Total loans receivable	421,559	464,539
First Mortgage [Member] \| Real estate [Member] \| Consumer [Member] \| Universal Bancorp [Member]
Loans acquired	27,344	30,694
Second Mortgage [Member] \| Consumer [Member]
Total loans receivable	75,218	77,072
Second Mortgage [Member] \| Real estate [Member] \| Consumer [Member] \| Universal Bancorp [Member]
Loans acquired	7,236	8,032
Automobile Loan [Member] \| Consumer [Member]
Total loans receivable	56,855	43,667
Automobile Loan [Member] \| Other [Member] \| Consumer [Member] \| Universal Bancorp [Member]
Loans acquired	805	1,138
Boat/RVs [Member] \| Consumer [Member]
Total loans receivable	220,470	216,608
Boat/RVs [Member] \| Other [Member] \| Consumer [Member] \| Universal Bancorp [Member]
Loans acquired	45	97
Other [Member] \| Consumer [Member]
Total loans receivable	7,091	6,893
Other [Member] \| Other [Member] \| Consumer [Member] \| Universal Bancorp [Member]
Loans acquired	388	523
Commercial and Industrial [Member] \| Commercial Segment [Member]
Total loans receivable	156,950	149,359
Commercial and Industrial [Member] \| Other [Member] \| Commercial Segment [Member] \| Universal Bancorp [Member]
Loans acquired	$ 9,657	$ 10,571

Certain loans acquired in transfer not accounted for as debt securities carrying amount gross.

No definition available.

Name:	mfsf_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesCarryingAmountGross
Namespace Prefix:	mfsf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538

+ Details

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

- Definition

The undiscounted sum of all amounts, including amounts deemed principal, interest, fees, penalties, and other under the loan, owed to the investor at the reporting date, whether or not currently due and whether or not any such amounts have been written or charged off by the investor. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

+ Details

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

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

+ Details

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

- Details

Name:	us-gaap_BusinessAcquisitionAxis=mfsf_UniversalBancorpMember
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_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_RealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=mfsf_OtherLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
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_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_FirstMortgageMember
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:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_SecondMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_AutomobileLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mfsf_ConsumerRecreationalVehicleFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mfsf_OtherClassOfFinancingReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialAndIndustrialSectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: