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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Total investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.

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Including the current and noncurrent portions, the carrying value of junior subordinated long-term debt owed to unconsolidated subsidiary trusts as of the balance sheet date. Such debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets and was initially scheduled to be repaid after one year or beyond the normal operating cycle if longer.

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Sum of the carrying amounts as of the balance sheet date of all liabilities that are recognized. Liabilities are probable future sacrifices of economic benefits arising from present obligations of an entity to transfer assets or provide services to other entities in the future.

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Amount of liabilities and equity items, including the portion of equity attributable to noncontrolling interests, if any.

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The aggregate carrying amounts, as of the balance sheet date, of assets not separately disclosed in the balance sheet.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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Note 25 - Mercantile Bank Corporation (Parent Company Only) Condensed Financial Statements (Details) - Condensed Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 29, 2012	Dec. 31, 2011
ASSETS
Other assets	$ 33,024,000us-gaap_OtherAssets	$ 30,165,000us-gaap_OtherAssets
Total assets	2,893,379,000us-gaap_Assets	1,426,966,000us-gaap_Assets
LIABILITIES AND SHAREHOLDERS’ EQUITY
Liabilities	2,565,241,000us-gaap_Liabilities	1,273,641,000us-gaap_Liabilities
Subordinated debentures	54,472,000	32,990,000		32,000,000
Shareholders’ equity	328,138,000us-gaap_StockholdersEquity	153,325,000us-gaap_StockholdersEquity	146,590,000us-gaap_StockholdersEquity		164,999,000us-gaap_StockholdersEquity
Total liabilities and shareholders’ equity	2,893,379,000	1,426,966,000
Parent Company [Member]
ASSETS
Cash and cash equivalents	1,441,000	2,506,000	473,000		542,000
Investment in bank subsidiary	361,355,000	179,706,000
Other assets	20,948,000	4,740,000
Total assets	383,744,000	186,952,000
LIABILITIES AND SHAREHOLDERS’ EQUITY
Liabilities	1,134,000	637,000
Subordinated debentures	54,472,000	32,990,000
Shareholders’ equity	328,138,000	153,325,000
Total liabilities and shareholders’ equity	$ 383,744,000	$ 186,952,000