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

No definition available.

Name:	msfg_GoodwillAndIntangibleAssetsAdditionalDisclosureAbstract
Namespace Prefix:	msfg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Reclassification information.

No definition available.

Name:	msfg_PriorPeriodReclassificationAbstract
Namespace Prefix:	msfg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The impact on prior period net income or stockholders' equity from reclassifications to conform to current presentation.

No definition available.

Name:	msfg_ReclassificationEffectOnPriorYearNetIncomeOrShareholdersEquity
Namespace Prefix:	msfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the stock dividends rate reported by transferring the fair value, as of the ex-dividend date, of the stock issued from retained earnings to common stock and additional paid-in capital.

No definition available.

Name:	msfg_StockDividendRateReportedByTransferringFairValueOfStockIssuedFromRetainedEarningsToCommonStockAndAdditionalPaidInCapital
Namespace Prefix:	msfg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the stock dividends rate reported by transferring the par value of the stock issued from retained earnings to common stock.

No definition available.

Name:	msfg_StockDividendRateReportedByTransferringParValueOfStockIssuedFromRetainedEarningsToCommonStock
Namespace Prefix:	msfg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

No definition available.

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

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

No definition available.

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

No definition available.

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

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

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

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CoreDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: