Represents the maturity period of the borrowings from issuance.

No definition available.

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

- Definition

Represents the maximum period available to the entity for deferring the interest payments.

+ References

No definition available.

+ Details

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

- Definition

Represents the period at par after which the debt can be called.

+ References

No definition available.

+ Details

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

- Definition

Represents the investment made by the entity in the common stock of the trust.

+ References

No definition available.

+ Details

Name:	msfg_InvestmentInCommonStockOfTrust
Namespace Prefix:	msfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the number of separate trusts formed by the entity, which issued floating rate trust preferred securities as a part of pooled offerings.

+ References

No definition available.

+ Details

Name:	msfg_NumberOfSeparateTrustsFormedForIssuingFloatingRateTrustPreferredSecurities
Namespace Prefix:	msfg_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of trusts acquired by the entity from prior acquisition.

+ References

No definition available.

+ Details

Name:	msfg_NumberOfTrustsAcquiredFromPriorAcquisition
Namespace Prefix:	msfg_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of trusts redeemed by the entity.

+ References

No definition available.

+ Details

Name:	msfg_NumberOfTrustsRedeemed
Namespace Prefix:	msfg_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Details

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

- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 10

-Section F

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Article 5

-Subsection 19, 20, 22

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=msfg_HarrodsburgStatutoryTrust1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=msfg_Trust1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=msfg_Trust2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=msfg_Trust3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=msfg_Trust4Member
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SubordinatedDebtMember
Namespace Prefix:
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SUBORDINATED DEBENTURES (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014 item	Dec. 31, 2014 item	Dec. 31, 2013
SUBORDINATED DEBENTURES.
Number of separate trusts formed that issued floating rate trust preferred securities		4
Number of trusts acquired from prior acquisition	1
Number of trusts redeemed	1msfg_NumberOfTrustsRedeemed
Investment in the common stock of the trust		$ 1,239msfg_InvestmentInCommonStockOfTrust	$ 1,394msfg_InvestmentInCommonStockOfTrust
Subordinated Debentures
Maximum period available for deferral of interest payments		5 years
Amount		41,239us-gaap_SubordinatedDebt	46,394us-gaap_SubordinatedDebt
Trust 1
Subordinated Debentures
Amount		8,248	8,248
Variable rate basis		LIBOR
Rate at the end of the period (as a percent)		3.50%
Trust 1 \| Libor
Subordinated Debentures
Variable rate margin (as a percent)		3.25%
Trust 2
Subordinated Debentures
Amount		14,433	14,433
Variable rate basis		LIBOR
Rate at the end of the period (as a percent)		3.51%
Trust 2 \| Libor
Subordinated Debentures
Variable rate margin (as a percent)		3.25%
Trust 3
Subordinated Debentures
Amount		7,217	7,217
Variable rate basis		LIBOR
Rate at the end of the period (as a percent)		3.39%
Trust 3 \| Libor
Subordinated Debentures
Variable rate margin (as a percent)		3.15%
Trust 4
Subordinated Debentures
Amount		11,341	11,341
Variable rate basis		LIBOR
Rate at the end of the period (as a percent)		1.87%
Trust 4 \| Libor
Subordinated Debentures
Variable rate margin (as a percent)		1.63%
Harrodsburg
Subordinated Debentures
Amount			$ 5,155
Variable rate basis		LIBOR
Harrodsburg \| Libor
Subordinated Debentures
Variable rate margin (as a percent)		3.15%
Subordinated debentures
Subordinated Debentures
Maturity period		30 years
Period at par after which the debt can be called		5 years