Represents details about measures that determines an executive's payout from an equity-based plan.

No definition available.

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- Definition

Represents the percentage payout from the incentive plan upon achievement of certain goals.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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Period Type:	duration

- Definition

Represents the vesting percentage of stock awards vesting quarterly on May 1, August 1, and November 1, 2015, and February 1, 2016.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the executive's eligibility for payout from an equity-based plan based upon a percentage weighting of the entity's earnings per share performance as a criteria for payout.

+ References

No definition available.

+ Details

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- Definition

Represents the executive's eligibility for payout based upon a percentage weighting of the entity's return on assets as a criteria for payout.

+ References

No definition available.

+ Details

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- Definition

Represents the executive's eligibility for payout from an equity-based plan based upon a percentage weighting of the entity's total shareholder return as a criteria for payout.

+ References

No definition available.

+ Details

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- Definition

The period over which performance measures and goals are determined and associated dividends accrued and paid at the end of the period.

+ References

No definition available.

+ Details

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- References

No definition available.

+ Details

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- Definition

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.

+ References

No definition available.

+ Details

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- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
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- Details

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- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
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Data Type:	na
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- Details

Name:	us-gaap_TitleOfIndividualAxis=us-gaap_DirectorMember
Namespace Prefix:
Data Type:	na
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- Details

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Namespace Prefix:
Data Type:	na
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- Details

Name:	msfg_PerformancePayoutAxis=msfg_TargetMember
Namespace Prefix:
Data Type:	na
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- Details

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STOCK PLANS AND STOCK BASED COMPENSATION - Performance Measures and Additional Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Jun. 30, 2016	Mar. 31, 2016
Additional disclosures
Shares of common stock granted		17,976	358,000
Compensation expense	$ 100		$ 89
Performance units \| Executive officers
Stock-based compensation
Performance period	3 years
Performance Measures
Return on assets criteria (as a percent)	50.00%
Total shareholder return criteria (as a percent)	25.00%
Earnings per share criteria (as a percent)	25.00%
Additional disclosures
Vesting period	3 years
Shares of common stock granted	6,528		16,152
Compensation expense	$ 49		$ 26
Restricted stock
Additional disclosures
Shares of common stock granted	12,802
Restricted stock \| Directors
Additional disclosures
Quarterly vesting percentage of stock awards	25.00%
Threshold \| Performance units \| Executive officers
Performance Measures
Performance levels (as a percent)	0.00%
Target \| Performance units \| Executive officers
Performance Measures
Performance levels (as a percent)	100.00%
Superior \| Performance units \| Executive officers
Performance Measures
Performance levels (as a percent)	150.00%