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Note 5 - Deposits (Tables) | 3 Months Ended
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Mar. 31, 2019
Notes Tables |
Summary of Deposits and Percentage Change in Deposits [Table Text Block] |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Percent |
|  | March 31, 2019 |  |  | December 31, 2018 |  |  | Increase |
|  | Balance |  |  | % |  |  | Balance |  |  | % |  |  | (Decrease) |
Noninterest-bearing checking |  | $ | 857,734,000 |  |  |  | 32.9 | % |  | $ | 889,784,000 |  |  |  | 36.1 | % |  |  | (3.6 | %)
Interest-bearing checking |  |  | 324,802,000 |  |  |  | 12.4 |  |  |  | 339,089,000 |  |  |  | 13.8 |  |  |  | (4.2 | )
Money market |  |  | 484,035,000 |  |  |  | 18.5 |  |  |  | 434,333,000 |  |  |  | 17.6 |  |  |  | 11.4 |
Savings |  |  | 295,383,000 |  |  |  | 11.3 |  |  |  | 317,014,000 |  |  |  | 12.9 |  |  |  | (6.8 | )
Time, under $100,000 |  |  | 198,243,000 |  |  |  | 7.6 |  |  |  | 160,092,000 |  |  |  | 6.5 |  |  |  | 23.8 |
Time, $100,000 and over |  |  | 265,242,000 |  |  |  | 10.2 |  |  |  | 210,164,000 |  |  |  | 8.5 |  |  |  | 26.2 |
Total local deposits |  |  | 2,425,439,000 |  |  |  | 92.9 |  |  |  | 2,350,476,000 |  |  |  | 95.4 |  |  |  | 3.2 |
Out-of-area time, under $100,000 |  |  | 0 |  |  | NA |  |  |  | 0 |  |  | NA |  |  | NA |
Out-of-area time, $100,000 and over |  |  | 185,535,000 |  |  |  | 7.1 |  |  |  | 113,232,000 |  |  |  | 4.6 |  |  |  | 63.9 |
Total out-of-area deposits |  |  | 185,535,000 |  |  |  | 7.1 |  |  |  | 113,232,000 |  |  |  | 4.6 |  |  |  | 63.9 |
Total deposits |  | $ | 2,610,974,000 |  |  |  | 100.0 | % |  | $ | 2,463,708,000 |  |  |  | 100.0 | % |  |  | 6.0 | %

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- Definition Tabular disclosure of deposits and the percentage change in deposits. + References No definition available. + Details
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Namespace Prefix: | mbwm_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
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- References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration