Name:	msbi_FinancingReceivableAllowanceForCreditLossesForLoansAcquiredWithDeterioratedCreditQuality
Namespace Prefix:	msbi_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The valuation allowance for financing receivables that are expected to be uncollectible nonimpaired loans that were collectively evaluated for impairment.

No definition available.

Name:	msbi_FinancingReceivableAllowanceForCreditLossesForNonimpairedLoansCollectivelyEvaluatedForImpairment
Namespace Prefix:	msbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The balance of financing receivables nonimpaired loans that were collectively evaluated for impairment.

No definition available.

Name:	msbi_FinancingReceivableNonimpairedLoansCollectivelyEvaluatedForImpairment
Namespace Prefix:	msbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The balance of financing receivables loans acquired with deteriorated credit quality.

No definition available.

Name:	msbi_FinancingReceivableNonimpairedLoansLoansAcquiredWithDeterioratedCreditQuality
Namespace Prefix:	msbi_
Data Type:	xbrli:monetaryItemType
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N/A

No definition available.

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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. Includes loans and leases covered under loss sharing agreements.

No definition available.

Name:	msbi_LoansAndLeasesReceivableGrossCarryingAmountCoveredAndNotCovered
Namespace Prefix:	msbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Data Type:	xbrli:monetaryItemType
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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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- References

No definition available.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward
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The balance of financing receivables that were collectively evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 942
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-Section S99
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Balance Type:	credit
Period Type:	instant

Amount of expense related to estimated loss from loan and lease transactions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
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Name:	us-gaap_CollateralAxis=us-gaap_CommercialLoanMember
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Name:	us-gaap_CollateralAxis=us-gaap_CommercialRealEstateMember
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Name:	us-gaap_CollateralAxis=us-gaap_ConstructionLoansMember
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Name:	us-gaap_CollateralAxis=us-gaap_ResidentialRealEstateMember
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Namespace Prefix:
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Name:	us-gaap_CollateralAxis=us-gaap_ConsumerPortfolioSegmentMember
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