Name:	msfg_AllowanceForLoanLossesBasisPointsFloorOfHistoricalLossesUsedToReflectMinimumLevelOfRisk
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Data Type:	num:percentItemType
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Period Type:	duration

The period of historical loss experience used to determine the specific and general components of the allowance for loan losses.

No definition available.

Name:	msfg_AllowanceForLoanLossesHistoricalLossExperiencePeriodUsedToDetermineSpecificAndGeneralComponentsOfAllowance
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Data Type:	xbrli:durationItemType
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Represents the number of components in which the amount of impairment of securities is spilt, if they do not meet the criteria as per accounting policy of the entity.

No definition available.

Name:	msfg_AvailableForSaleSecuritiesNumberOfComponentsInWhichAmountOfImpairmentSplit
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Data Type:	xbrli:integerItemType
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The maximum period of maturities of deposits with other financial institutions for the deposits to be included in cash and cash equivalents.

No definition available.

Name:	msfg_CashAndCashEquivalentsMaximumMaturityPeriodOfInterestBearingDepositsWithOtherFinancialInstitutions
Namespace Prefix:	msfg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the amount of impaired loans for which a specific reserve is established as a component of the allowance.

No definition available.

Name:	msfg_FinancingReceivableAllowanceForCreditLossImpairedLoansAmountForEstablishmentOfSpecificReserve
Namespace Prefix:	msfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Represents the past due period for payments of loans for recognizing the interest income.

No definition available.

Name:	msfg_FinancingReceivablePaymentsPastDuePeriodForInterestIncomeEvaluation
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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the financing term of loans.

No definition available.

Name:	msfg_FinancingReceivableTermOfFinancing
Namespace Prefix:	msfg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_AccountsNotesAndLoansReceivableLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Percentage of voting equity interests acquired at the acquisition date in the business combination.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

Name:	us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossAdditionalInformationAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

Name:	us-gaap_LoansAndLeasesReceivableDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_BusinessAcquisitionAxis=msfg_CheviotFinancialCorpMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_BusinessAcquisitionAxis=msfg_MBTBancorpMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
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