XML 52 R42.htm IDEA: XBRL DOCUMENT
v3.21.2

Note 3 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($) | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020
With no related allowance recorded, unpaid principal balance | $ 20,453,000 |  | $ 20,453,000 |  | $ 26,892,000
With no related allowance recorded, principal balance | 19,102,000 |  | 19,102,000 |  | 24,738,000
With no related allowance recorded, average recorded principal balance | 18,958,000 | $ 15,506,000 | 20,892,000 | $ 15,459,000 |
With related allowance recorded, unpaid principal balance | 4,326,000 |  | 4,326,000 |  | 2,266,000
With related allowance recorded, principal balance | 4,307,000 |  | 4,307,000 |  | 2,220,000
Related allowance | 765,000 |  | 765,000 |  | 551,000
With related allowance recorded, average recorded principal balance | 4,703,000 | 2,667,000 | 3,387,000 | 2,870,000 |
Total unpaid principal balance | 24,779,000 |  | 24,779,000 |  | 29,158,000
Total principal balance | 23,409,000 |  | 23,409,000 |  | 26,958,000
Total average recorded principal balance | 23,661,000 | 18,173,000 | 24,279,000 | 18,329,000 |
Commercial Portfolio Segment [Member] |  |  |  |  |
With no related allowance recorded, unpaid principal balance | 15,666,000 |  | 15,666,000 |  | 21,365,000
With no related allowance recorded, principal balance | 15,609,000 |  | 15,609,000 |  | 21,176,000
With no related allowance recorded, average recorded principal balance | 15,479,000 | 11,696,000 | 17,396,000 | 11,771,000 |
With related allowance recorded, unpaid principal balance | 3,728,000 |  | 3,728,000 |  | 1,268,000
With related allowance recorded, principal balance | 3,728,000 |  | 3,728,000 |  | 1,239,000
Related allowance | 544,000 |  | 544,000 |  | 138,000
With related allowance recorded, average recorded principal balance | 4,034,000 | 1,544,000 | 2,586,000 | 1,846,000 |
Total unpaid principal balance | 19,394,000 |  | 19,394,000 |  | 22,633,000
Total principal balance | 19,337,000 |  | 19,337,000 |  | 22,415,000
Total average recorded principal balance | 19,513,000 | 13,240,000 | 19,982,000 | 13,617,000 |
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |
With no related allowance recorded, unpaid principal balance | 2,900,000 |  | 2,900,000 |  | 6,242,000
With no related allowance recorded, principal balance | 2,843,000 |  | 2,843,000 |  | 6,242,000
With no related allowance recorded, average recorded principal balance | 2,759,000 | 7,416,000 | 3,836,000 | 8,282,000 |
With related allowance recorded, unpaid principal balance | 2,802,000 |  | 2,802,000 |  | 343,000
With related allowance recorded, principal balance | 2,802,000 |  | 2,802,000 |  | 343,000
Related allowance | 449,000 |  | 449,000 |  | 53,000
With related allowance recorded, average recorded principal balance | 2,888,000 | 940,000 | 1,617,000 | 1,128,000 |
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member] |  |  |  |  |
With no related allowance recorded, unpaid principal balance | 0 |  | 0 |  | 0
With no related allowance recorded, principal balance | 0 |  | 0 |  | 0
With no related allowance recorded, average recorded principal balance | 0 | 326,000 | 0 | 234,000 |
With related allowance recorded, unpaid principal balance | 0 |  | 0 |  | 0
With related allowance recorded, principal balance | 0 |  | 0 |  | 0
Related allowance | 0 |  | 0 |  | 0
With related allowance recorded, average recorded principal balance | 0 | 0 | 0 | 96,000 |
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member] |  |  |  |  |
With no related allowance recorded, unpaid principal balance | 12,674,000 |  | 12,674,000 |  | 14,782,000
With no related allowance recorded, principal balance | 12,674,000 |  | 12,674,000 |  | 14,593,000
With no related allowance recorded, average recorded principal balance | 12,674,000 | 3,645,000 | 13,374,000 | 3,053,000 |
With related allowance recorded, unpaid principal balance | 775,000 |  | 775,000 |  | 763,000
With related allowance recorded, principal balance | 775,000 |  | 775,000 |  | 734,000
Related allowance | 89,000 |  | 89,000 |  | 77,000
With related allowance recorded, average recorded principal balance | 994,000 | 436,000 | 813,000 | 538,000 |
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member] |  |  |  |  |
With no related allowance recorded, unpaid principal balance | 0 |  | 0 |  | 341,000
With no related allowance recorded, principal balance | 0 |  | 0 |  | 341,000
With no related allowance recorded, average recorded principal balance | 0 | 309,000 | 163,000 | 199,000 |
With related allowance recorded, unpaid principal balance | 151,000 |  | 151,000 |  | 162,000
With related allowance recorded, principal balance | 151,000 |  | 151,000 |  | 162,000
Related allowance | 6,000 |  | 6,000 |  | 8,000
With related allowance recorded, average recorded principal balance | 152,000 | 168,000 | 156,000 | 84,000 |
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member] |  |  |  |  |
With no related allowance recorded, unpaid principal balance | 92,000 |  | 92,000 |  | 0
With no related allowance recorded, principal balance | 92,000 |  | 92,000 |  | 0
With no related allowance recorded, average recorded principal balance | 46,000 | 0 | 23,000 | 3,000 |
With related allowance recorded, unpaid principal balance | 0 |  | 0 |  | 0
With related allowance recorded, principal balance | 0 |  | 0 |  | 0
Related allowance | 0 |  | 0 |  | 0
With related allowance recorded, average recorded principal balance | 0 | 0 | 0 | 0 |
Retail Portfolio Segment [Member] |  |  |  |  |
With no related allowance recorded, unpaid principal balance | 4,787,000 |  | 4,787,000 |  | 5,527,000
With no related allowance recorded, principal balance | 3,493,000 |  | 3,493,000 |  | 3,562,000
With no related allowance recorded, average recorded principal balance | 3,479,000 | 3,810,000 | 3,496,000 | 3,688,000 |
With related allowance recorded, unpaid principal balance | 598,000 |  | 598,000 |  | 998,000
With related allowance recorded, principal balance | 579,000 |  | 579,000 |  | 981,000
Related allowance | 221,000 |  | 221,000 |  | 413,000
With related allowance recorded, average recorded principal balance | 669,000 | 1,123,000 | 801,000 | 1,024,000 |
Total unpaid principal balance | 5,385,000 |  | 5,385,000 |  | 6,525,000
Total principal balance | 4,072,000 |  | 4,072,000 |  | 4,543,000
Total average recorded principal balance | 4,148,000 | 4,933,000 | 4,297,000 | 4,712,000 |
Retail Portfolio Segment [Member] | Home Equity and Other [Member] |  |  |  |  |
With no related allowance recorded, unpaid principal balance | 1,291,000 |  | 1,291,000 |  | 1,072,000
With no related allowance recorded, principal balance | 1,208,000 |  | 1,208,000 |  | 987,000
With no related allowance recorded, average recorded principal balance | 1,223,000 | 1,305,000 | 1,093,000 | 1,273,000 |
With related allowance recorded, unpaid principal balance | 182,000 |  | 182,000 |  | 300,000
With related allowance recorded, principal balance | 163,000 |  | 163,000 |  | 283,000
Related allowance | 142,000 |  | 142,000 |  | 241,000
With related allowance recorded, average recorded principal balance | 197,000 | 470,000 | 232,000 | 455,000 |
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member] |  |  |  |  |
With no related allowance recorded, unpaid principal balance | 3,496,000 |  | 3,496,000 |  | 4,455,000
With no related allowance recorded, principal balance | 2,285,000 |  | 2,285,000 |  | 2,575,000
With no related allowance recorded, average recorded principal balance | 2,256,000 | 2,505,000 | 2,403,000 | 2,415,000 |
With related allowance recorded, unpaid principal balance | 416,000 |  | 416,000 |  | 698,000
With related allowance recorded, principal balance | 416,000 |  | 416,000 |  | 698,000
Related allowance | 79,000 |  | 79,000 |  | $ 172,000
With related allowance recorded, average recorded principal balance | $ 472,000 | $ 653,000 | $ 569,000 | $ 569,000 |

X
- Definition Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5258-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of allowance for credit losses related to recorded investment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableRelatedAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of average investment of impaired financing receivables for which there is no related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5258-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of investment in impaired financing receivables for which there is no related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of unpaid principal balance of impaired financing receivables for which there is no related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5258-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of investment in impaired financing receivables for which there is a related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_CommercialAndIndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_VacantLandAndLandDevelopmentAndResidentialConstructionLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_RealEstateOwnerOccupiedLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_RealEstateNonOwnerOccupiedLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_RealEstateMultiFamilyAndResidentialRentalLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=mbwm_RetailPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_HomeEquityAndOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbwm_OneToFourFamilyMortgagesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |