XML 95 R77.htm IDEA: XBRL DOCUMENT
v3.24.0.1

Note 5 - Mortgage Loan Servicing (Details Textual) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022
Continuing Involvement with Transferred Financial Assets Custodial Escrow Balance | $ 10,100 | $ 11,600
Valuation Allowance for Impairment of Recognized Servicing Assets, Balance | 0 | 0
Servicing Asset at Fair Value, Amount | $ 19,300 | $ 17,700
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate | 11.00% | 11.25%
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Prepayment Speed | 7.44% | 6.60%
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Expected Credit Losses | 0.29% | 0.28%
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Weighted Average Life (Year) | 8 years 7 months 6 days | 8 years 10 months 24 days
Maximum [Member] |  |
Late and Ancillary Fee Income Generated by Servicing Financial Assets, Amount | $ 100 | $ 100

X
- Definition Custodial escrow balances maintained in connection with serviced loans. + References No definition available. + Details
Name: | mbwm_ContinuingInvolvementWithTransferredFinancialAssetsCustodialEscrowBalance
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition All amounts that are due to the servicer of a financial asset, excluding contractually specified servicing fees. + References No definition available. + Details
Name: | mbwm_LateAndAncillaryFeeIncomeGeneratedByServicingFinancialAssetsAmount
Namespace Prefix: | mbwm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481229/860-50-50-3 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481260/860-50-45-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481260/860-50-45-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481260/860-50-45-2 + Details
Name: | us-gaap_ServicingAssetAtFairValueAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Discount rate used to estimate the fair value of servicing assets and servicing liabilities. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481229/860-50-50-2 + Details
Name: | us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of contractually collectible principal associated with a financial asset expected not to be collected due to default by the borrower. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481229/860-50-50-2 + Details
Name: | us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueExpectedCreditLosses
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Estimated rate of prepayments of principal on servicing assets and servicing liabilities. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481229/860-50-50-2 + Details
Name: | us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValuePrepaymentSpeed
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average life of financial assets and financial liabilities, 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/2009/role/commonPracticeRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481229/860-50-50-2 + Details
Name: | us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueWeightedAverageLife1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Reflects the estimated amount of impairment as of the balance sheet date of recognized servicing assets that are being amortized in proportion to and over the period of estimated net servicing income or loss. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (e)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481229/860-50-50-4 + Details
Name: | us-gaap_ValuationAllowanceForImpairmentOfRecognizedServicingAssetsBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |