XML 55 R45.htm IDEA: XBRL DOCUMENT v3.4.0.3

Note 3 - Loans and Allowance for Loan Losses (Details) - Activity in Allowance for Loan Losses and the Recorded Investments in Loans - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for loan losses	$ 600,000	$ (400,000)
Ending balance	2,295,668,000		$ 2,277,727,000
Originated Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	15,233,000	19,299,000
Ending balance	15,972,000	20,251,000
Allowance for loan losses: individually evaluated for impairment	1,088,000	10,366,000
Allowance for loan losses: collectively evaluated for impairment	14,884,000	9,885,000
Provision for loan losses	671,000	(457,000)
Charge-offs	(475,000)	(441,000)
Recoveries	543,000	1,850,000
Ending balance	1,687,476,000	1,328,713,000	1,616,587,000
Loans: individually evaluated for impairment	17,729,000	45,450,000
Loans: collectively evaluated for impairment	1,669,747,000	1,283,263,000
Acquired Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	448,000	742,000
Ending balance	290,000	799,000
Provision for loan losses	(71,000)	57,000
Charge-offs	0	(7,000)
Recoveries	(87,000)	7,000
Ending balance	608,192,000		661,140,000
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance	1,974,450,000		1,946,696,000
Commercial Portfolio Segment [Member] | Originated Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	13,672,000	17,736,000
Ending balance	13,924,000	18,977,000
Allowance for loan losses: individually evaluated for impairment	913,000	10,158,000
Allowance for loan losses: collectively evaluated for impairment	13,011,000	8,819,000
Provision for loan losses	94,000	(499,000)
Charge-offs	(89,000)	(78,000)
Recoveries	247,000	1,818,000
Ending balance	1,562,777,000	1,230,841,000	1,493,516,000
Loans: individually evaluated for impairment	16,551,000	44,257,000
Loans: collectively evaluated for impairment	1,546,226,000	1,186,584,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	420,000	681,000
Ending balance	266,000	622,000
Provision for loan losses	(110,000)	(60,000)
Charge-offs	0	0
Recoveries	(44,000)	1,000
Ending balance	411,673,000		453,180,000
Retail Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance	321,218,000		331,031,000
Retail Portfolio Segment [Member] | Originated Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,421,000	1,487,000
Ending balance	1,834,000	1,235,000
Allowance for loan losses: individually evaluated for impairment	175,000	208,000
Allowance for loan losses: collectively evaluated for impairment	1,659,000	1,027,000
Provision for loan losses	503,000	79,000
Charge-offs	(386,000)	(363,000)
Recoveries	296,000	32,000
Ending balance	124,699,000	97,872,000	123,071,000
Loans: individually evaluated for impairment	1,178,000	1,193,000
Loans: collectively evaluated for impairment	123,521,000	96,679,000
Retail Portfolio Segment [Member] | Acquired Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	28,000	61,000
Ending balance	24,000	177,000
Provision for loan losses	39,000	117,000
Charge-offs	0	(7,000)
Recoveries	(43,000)	6,000
Ending balance	196,519,000		$ 207,960,000
Unallocated Financing Receivables [Member] | Originated Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	140,000	76,000
Ending balance	214,000	39,000
Allowance for loan losses: individually evaluated for impairment	0	0
Allowance for loan losses: collectively evaluated for impairment	214,000	39,000
Provision for loan losses	74,000	(37,000)
Charge-offs	0	0
Recoveries	0	0
Unallocated Financing Receivables [Member] | Acquired Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	0	0
Ending balance	0	0
Provision for loan losses	0	0
Charge-offs	0	0
Recoveries	$ 0	$ 0

X

- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

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

+ Details

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

X

- Definition

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

+ References

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

+ Details

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

X

- Definition

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

+ References

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

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- 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

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

X

- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(4)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount of direct write-downs of financing receivables charged against the allowance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

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

+ References

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

+ Details

Name:	us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

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

+ References

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

+ Details

Name:	us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65884687&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5074-111524

+ Details

Name:	us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

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

+ References

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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

+ Details

Name:	us-gaap_ProvisionForLoanAndLeaseLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=mbwm_OriginatedLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=mbwm_AcquiredLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
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_FinancingReceivablePortfolioSegmentAxis=us-gaap_UnallocatedFinancingReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: