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Note 1 - Summary of Significant Accounting Policies (Details) - Year-end Mortgage Loans Held for Sale (USD $) | Dec. 31, 2014 | Dec. 31, 2013
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Year-end Mortgage Loans Held for Sale [Abstract] |  |
Mortgage loans held for sale | $ 1,574,000 us-gaap_LoansHeldForSaleMortgages | $ 1,115,000 us-gaap_LoansHeldForSaleMortgages
Less: Allowance to adjust to lower of cost or market | 0 us-gaap_LoansAndLeasesReceivableOtherAllowance | 0 us-gaap_LoansAndLeasesReceivableOtherAllowance
Mortgage loans held for sale, net | $ 1,574,000 mbwm_MortgageLoansHeldForSaleNet | $ 1,115,000 mbwm_MortgageLoansHeldForSaleNet

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- Definition Amount classified as mortgage loans attributable to disposal group held for sale or disposed of, net of allowance to adjust to lower of cost or market. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities. + References No definition available. + Details
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- Details
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- Definition The allowance for other loan and lease losses represents the reserve to cover probable credit losses related to specifically identified other loans and leases, as well as probable credit losses inherent in the remainder of the other loan portfolio as of the balance sheet date. For banks, include currently required allocated transfer risk reserves. Include carryover of or adjustments to the allowance for other loan losses in connection with business combinations determined to be appropriate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(d)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph d -Article 9 Reference 3: 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=35738203&loc=SL6953423-111524 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 6 -Section L -Subsection 1 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18832-111554 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section S99 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18805-111554 + Details
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- Definition Amount classified as mortgage loans attributable to disposal group held for sale or disposed of. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities. + 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=28367877&loc=d3e4428-111522 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(a)(3)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6490309&loc=d3e48678-111004 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Permanent Investor -URI http://asc.fasb.org/extlink&oid=6520390 + Details
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