Mercantile Bank (MBWM) 10-K 10 Mar 15 2014 FY Annual report Financial data

Document_And_Entity_Informatio

Document And Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Mar. 06, 2015	Jun. 30, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	MERCANTILE BANK CORPORATION
Document Type	10-K
Current Fiscal Year End Date	-19
Entity Common Stock, Shares Outstanding		16,888,530
Entity Public Float			$377,000,000
Amendment Flag	FALSE
Entity Central Index Key	1042729
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014		Dec. 31, 2013
ASSETS
Cash and due from banks	$43,754,000		$17,149,000
Interest-bearing deposits	117,777,000		6,389,000
Federal funds sold	11,207,000		123,427,000
Total cash and cash equivalents	172,738,000		146,965,000
Securities available for sale	432,912,000	[1]	131,178,000	[1]
Federal Home Loan Bank stock	13,699,000	[2]	11,961,000	[2]
Loans	2,089,277,000		1,053,243,000
Allowance for loan losses	-20,041,000		-22,821,000
Loans, net	2,069,236,000		1,030,422,000
Premises and equipment, net	48,812,000		24,898,000
Bank owned life insurance	57,861,000		51,377,000
Goodwill	49,473,000		0
Cored deposit intangible	15,624,000		0
Other assets	33,024,000		30,165,000
Total assets	2,893,379,000		1,426,966,000
LIABILITIES AND SHAREHOLDERS' EQUITY
Noninterest-bearing	558,738,000		224,580,000
Interest-bearing	1,718,177,000		894,331,000
Total deposits	2,276,915,000		1,118,911,000
Securities sold under agreements to repurchase	167,569,000		69,305,000
Federal Home Loan Bank advances	54,022,000		45,000,000
Subordinated debentures	54,472,000		32,990,000
Accrued interest and other liabilities	12,263,000		7,435,000
Total liabilities	2,565,241,000		1,273,641,000
Shareholders' equity
Preferred stock, no par value; 1,000,000 shares authorized; 0 shares outstanding at December 31, 2014 and December 31, 2013	0		0
Common stock, no par value; 40,000,000 shares authorized; 16,976,839 shares outstanding at December 31, 2014 and 8,739,108 shares outstanding at December 31, 2013	317,904,000		162,999,000
Retained earnings (deficit)	10,218,000		-4,101,000
Accumulated other comprehensive income (loss)	16,000		-5,573,000
Total shareholders’ equity	328,138,000		153,325,000
Total liabilities and shareholders’ equity	$2,893,379,000		$1,426,966,000
[1]	See Note 18 for a description of the fair value hierarchy as well as a disclosure of levels for classes of financial assets and liabilities.
[2]	It is not practical to determine the fair value of FHLB stock due to transferability restrictions.

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parentheticals) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Preferred stock, par value (in Dollars per share)	$0	$0
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value (in Dollars per share)	$0	$0
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares outstanding	16,976,839	8,739,108

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Interest income
Loans, including fees	$80,824,000	$52,924,000	$53,898,000
Securities, taxable	6,417,000	4,134,000	4,383,000
Securities, tax-exempt	1,643,000	951,000	1,415,000
Federal funds sold	124,000	212,000	192,000
Interest-bearing deposits	110,000	21,000	29,000
Total interest income	89,118,000	58,242,000	59,917,000
Interest expense
Deposits	8,378,000	8,912,000	11,137,000
Short-term borrowings	122,000	80,000	157,000
Federal Home Loan Bank advances	636,000	533,000	993,000
Subordinated debentures and other borrowings	2,204,000	1,261,000	929,000
Total interest expense	11,340,000	10,786,000	13,216,000
Net interest income	77,778,000	47,456,000	46,701,000
Provision for loan losses	-3,000,000	-7,200,000	-3,100,000
Net interest income after provision for loan losses	80,778,000	54,656,000	49,801,000
Noninterest income
Service charges on deposit and sweep accounts	2,586,000	1,532,000	1,523,000
Credit and debit card fees	2,494,000	1,063,000	891,000
Mortgage banking activities	1,672,000	800,000	1,479,000
Earnings on bank owned life insurance	1,184,000	1,329,000	1,528,000
Payroll processing	782,000	660,000	591,000
Letter of credit fees	335,000	370,000	336,000
Rental income from other real estate owned	109,000	528,000	1,061,000
Other income	866,000	590,000	585,000
Total noninterest income	10,028,000	6,872,000	7,994,000
Noninterest expense
Salaries and benefits	33,703,000	20,298,000	19,367,000
Occupancy	4,637,000	2,547,000	2,501,000
Furniture and equipment rent, depreciation and maintenance	1,738,000	984,000	1,176,000
Data processing	5,869,000	3,440,000	3,193,000
Merger-related costs	5,447,000	1,246,000	0
Advertising	1,315,000	1,113,000	1,167,000
FDIC insurance costs	1,182,000	793,000	1,200,000
Problem asset costs	585,000	595,000	5,862,000
Other expense	11,134,000	5,387,000	5,158,000
Total noninterest expenses	65,610,000	36,403,000	39,624,000
Income before federal income tax expense	25,196,000	25,125,000	18,171,000
Federal income tax expense	7,865,000	8,092,000	5,636,000
Net income	17,331,000	17,033,000	12,535,000
Preferred stock dividends and accretion	0	0	1,030,000
Net income attributable to common shares	$17,331,000	$17,033,000	$11,505,000
Earnings per common share:
Basic (in Dollars per share)	$1.28	$1.96	$1.33
Diluted (in Dollars per share)	$1.28	$1.95	$1.30

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net income	$17,331,000	$17,033,000	$12,535,000
Other comprehensive income (loss):
Unrealized holding gains (losses) on securities available for sale	8,596,000	-11,960,000	-2,184,000
Fair value of interest rate swap	11,000	849,000	-1,113,000
	8,607,000	-11,111,000	-3,297,000
Tax effect of unrealized holding gains (losses) on securities available for sale	-3,014,000	4,186,000	1,229,000
Tax effect of fair value of interest rate swap	-4,000	-298,000	390,000
	-3,018,000	3,888,000	1,619,000
Other comprehensive income (loss), net of tax effect	5,589,000	-7,223,000	-1,678,000
Comprehensive income	$22,920,000	$9,810,000	$10,857,000

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in Shareholders' Equity (USD $)	Preferred Stock [Member]	Common Stock [Member]	Common Stock Warrant [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balances at Dec. 31, 2011	$20,331,000	$172,841,000	$1,138,000	($32,639,000)	$3,328,000	$164,999,000
Repurchase of preferred stock	-21,000,000					-21,000,000
Preferred stock dividends				-361,000		-361,000
Accretion of preferred stock	669,000			-669,000		0
Repurchase of stock warrant		-6,327,000	-1,138,000			-7,465,000
Employee stock purchase plan		39,000				39,000
Dividend reinvestment plan		14,000				14,000
Stock option exercises		551,000				551,000
Stock tendered for stock option exercises		-324,000				-324,000
Stock-based compensation expense		54,000				54,000
Cash dividends		-774,000				-774,000
Net income				12,535,000		12,535,000
Change in net unrealized gain on securities available for sale, net of tax effect					-955,000	-955,000
Change in fair value of interest rate swap, net tax effect					-723,000	-723,000
Balances at Dec. 31, 2012	0	166,074,000	0	-21,134,000	1,650,000	146,590,000
Employee stock purchase plan		19,000				19,000
Dividend reinvestment plan		33,000				33,000
Stock option exercises		700,000				700,000
Stock tendered for stock option exercises		-411,000				-411,000
Stock-based compensation expense		473,000				473,000
Cash dividends		-3,889,000				-3,889,000
Net income				17,033,000		17,033,000
Change in net unrealized gain on securities available for sale, net of tax effect					-7,774,000	-7,774,000
Change in fair value of interest rate swap, net tax effect					551,000	551,000
Balances at Dec. 31, 2013	0	162,999,000	0	-4,101,000	-5,573,000	153,325,000
Common stock issued in connection with Firstbank merger (8,087,272 shares)		173,310,000				173,310,000
Issuance of stock options to replace existing Firstbank options at merger date		1,664,000				1,664,000
Employee stock purchase plan		23,000				23,000
Dividend reinvestment plan		209,000				209,000
Stock option exercises		282,000				282,000
Stock grants to directors for retainer fees (7,375 shares)		155,000				155,000
Stock-based compensation expense		714,000				714,000
Cash dividends		-21,452,000		-3,012,000		-24,464,000
Net income				17,331,000		17,331,000
Change in net unrealized gain on securities available for sale, net of tax effect					5,582,000	5,582,000
Change in fair value of interest rate swap, net tax effect					7,000	7,000
Balances at Dec. 31, 2014	$0	$317,904,000	$0	$10,218,000	$16,000	$328,138,000

Consolidated_Statements_of_Cha1

Consolidated Statements of Changes in Shareholders' Equity (Parentheticals) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Sharеs issuеd using еmployее stock purchasе plan	1,150	1,098
Sharеs issuеd using stock option еxеrcisеs	2,845	51,055	50,930
Common Stock [Member]
Sharеs issuеd using еmployее stock purchasе plan	1,150	1,098	2,400
Sharеs issuеd using dividеnd rеinvеstmеnt plan	10,359	1,954	934
Sharеs issuеd using stock option еxеrcisеs	30,585	51,055	50,930
Number of shares tendered for stock option exercises		18,950	19,120
Cash dividends per common share (in Dollars per share)	2.48	0.45	0.09
Common stock issued in connection with Firstbank merger	8,087,272
Stock grants to directors for retainer fees	7,375

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities
Net income	$17,331,000	$17,033,000	$12,535,000
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	7,613,000	2,208,000	2,238,000
Accretion of acquired loans	-3,194,000	0	0
Provision for loan losses	-3,000,000	-7,200,000	-3,100,000
Deferred income tax expense	4,506,000	8,092,000	5,636,000
Stock-based compensation expense	714,000	473,000	54,000
Stock grants to directors for retainer fee	155,000	0	0
Proceeds from sales of mortgage loans held for sale	67,422,000	51,373,000	83,713,000
Origination of mortgage loans held for sale	-65,392,000	-48,321,000	-83,986,000
Net gain on sales of mortgage loans held for sale	-1,625,000	-658,000	-1,247,000
Net (gain) loss on sale and valuation write-downs of foreclosed assets	-894,000	-1,585,000	1,725,000
Earnings on bank owned life insurance	-1,184,000	-1,329,000	-1,528,000
Net change in:
Accrued interest receivable	-11,000	225,000	529,000
Other assets	1,795,000	8,465,000	-1,805,000
Accrued interest and other liabilities	-9,822,000	-94,000	2,267,000
Net cash from operating activities	14,414,000	28,682,000	17,031,000
Cash flows from investing activities
Cash received in merger	91,806,000	0	0
Securities available for sale	-19,874,000	-49,812,000	-69,956,000
Proceeds from:
Maturities, calls and repayments of securities available for sale	75,880,000	34,809,000	102,672,000
Proceeds from sales of securities available for sale	0	10,310,000	0
Proceeds from Federal Home Loan Bank stock redemption	5,527,000	0	0
Loan originations and payments, net	-90,853,000	-15,298,000	16,237,000
Purchases of premises and equipment, net	-2,150,000	-326,000	-571,000
Proceeds from sale of foreclosed assets	4,427,000	7,898,000	18,348,000
Net cash from (for) investing activities	64,763,000	-12,419,000	66,730,000
Cash flows from financing activities
Net decrease in time deposits	-58,927,000	-23,038,000	-47,257,000
Net increase (decrease) in all other deposits	-11,307,000	6,745,000	70,386,000
Net increase (decrease) in securities sold under agreements to repurchase	43,780,000	4,540,000	-7,804,000
Proceeds from Federal Home Loan Bank advances	0	10,000,000	20,000,000
Maturities and prepayments of Federal Home Loan Bank advances	-3,000,000	0	-30,000,000
Repurchase of preferred stock	0	0	-21,000,000
Repurchase of common stock warrant	0	0	-7,465,000
Proceeds from stock option exercises, net of cashless exercises	282,000	289,000	227,000
Employee stock purchase plan	23,000	19,000	39,000
Dividend reinvestment plan	209,000	33,000	14,000
Payment of cash dividends on preferred stock	0	0	-496,000
Payment of cash dividends to common shareholders	-24,464,000	-3,889,000	-774,000
Net cash for financing activities	-53,404,000	-5,301,000	-24,130,000
Net change in cash and cash equivalents	25,773,000	10,962,000	59,631,000
Cash and cash equivalents at beginning of period	146,965,000	136,003,000	76,372,000
Cash and cash equivalents at end of period	172,738,000	146,965,000	136,003,000
Cash paid during the year for:
Interest	11,439,000	11,059,000	13,741,000
Federal income taxes	2,625,000	0	0
Noncash financing and investing activities:
Transfers from loans to foreclosed assets	1,490,000	2,194,000	11,761,000
Common stock issued in connection with the Firstbank merger	$173,310,000	$0	$0

Note_1_Summary_of_Significant_

Note 1 - Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	NOTE 1 - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Principles of Consolidation: The consolidated financial statements include the accounts of Mercantile Bank Corporation (“Mercantile”) and its subsidiary, Mercantile Bank of Michigan (“Bank”), and of Mercantile Bank Real Estate Co., L.L.C. (“Mercantile Real Estate”) and Mercantile Insurance Center, Inc. (“Mercantile Insurance”), subsidiaries of our Bank, after elimination of significant intercompany transactions and accounts.
	We have five separate business trusts: Mercantile Bank Capital Trust I, Firstbank Capital Trust I, Firstbank Capital Trust II, Firstbank Capital Trust III and Firstbank Capital Trust IV (“our trusts”). Our trusts were formed to issue trust preferred securities. We issued subordinated debentures to our trusts in return for the proceeds raised from the issuance of the trust preferred securities. Our trusts are not consolidated, but instead we report the subordinated debentures issued to the trusts as liabilities.
	Nature of Operations: Mercantile was incorporated on July 15, 1997 to establish and own the Bank based in Grand Rapids, Michigan. The Bank began operations on December 15, 1997. We completed the merger of Firstbank Corporation (“Firstbank”), a Michigan corporation with approximately $1.5 billion in total assets and 46 branch locations, into Mercantile as of June 1, 2014.
	The Bank is a community-based financial institution. The Bank’s primary deposit products are checking, savings, and term certificate accounts, and its primary lending products are commercial loans, residential mortgage loans, and instalment loans. Substantially all loans are secured by specific items of collateral including business assets, real estate or consumer assets. Commercial loans are expected to be repaid from cash flow from operations of businesses. Real estate loans are secured by commercial or residential real estate. The Bank’s loan accounts and retail deposits are primarily with customers located in the communities in which we have bank office locations. As an alternative source of funds, the Bank has also issued certificates of deposit to depositors outside of its primary market areas. Substantially all revenues are derived from banking products and services and investment securities. While we monitor the revenue streams of the various products and services offered, we manage our business on the basis of one operating segment, banking.
	Mercantile Insurance was formed during 2002 through the acquisition of an existing shelf insurance agency. Insurance products are offered through an Agency and Institutions Agreement among Mercantile Insurance, the Bank and Hub International. The insurance products are marketed through a central facility operated by the Michigan Bankers Insurance Association, members of which include the insurance subsidiaries of various Michigan-based financial institutions and Hub International. Mercantile Insurance receives commissions based upon written premiums produced under the Agency and Institutions Agreement.
	Mercantile Real Estate was organized on July 21, 2003, principally to develop, construct, and own a facility in downtown Grand Rapids that serves as our Bank’s main office and Mercantile’s headquarters. This facility was placed into service during the second quarter of 2005.
	Use of Estimates: To prepare financial statements in conformity with accounting principles generally accepted in the United States of America, management makes estimates and assumptions based on available information. These estimates and assumptions affect the amounts reported in the financial statements and the disclosures provided, and actual results could differ. The allowance for loan losses and the fair values of financial instruments are particularly subject to change.
	Cash Flow Reporting: Cash and cash equivalents include cash on hand, demand deposits with other financial institutions, short-term investments (including securities with daily put provisions) and federal funds sold. Cash flows are reported net for customer loan and deposit transactions, interest-bearing time deposits with other financial institutions and short-term borrowings with maturities of 90 days or less.
	Securities: Debt securities classified as held to maturity are carried at amortized cost when management has the positive intent and ability to hold them to maturity. Debt securities are classified as available for sale when they might be sold prior to maturity. Equity securities with readily determinable fair values are classified as available for sale. Securities available for sale are carried at fair value, with unrealized holding gains and losses reported in other comprehensive income, net of tax. Federal Home Loan Bank stock is carried at cost.
	Interest income includes amortization of purchase premiums and accretion of discounts. Premiums and discounts on securities are amortized or accreted on the level-yield method without anticipating prepayments, except for mortgage-backed securities where prepayments are anticipated. Gains and losses on sales are recorded on the trade date and determined using the specific identification method.
	Declines in the fair value of debt securities below their amortized cost that are other than temporary (“OTTI”) are reflected in earnings or other comprehensive income, as appropriate. For those debt securities whose fair value is less than their amortized cost, we consider our intent to sell the security, whether it is more likely than not that we will be required to sell the security before recovery and whether we expect to recover the entire amortized cost of the security based on our assessment of the issuer’s financial condition. In analyzing an issuer’s financial condition, we consider whether the securities are issued by the federal government or its agencies, and whether downgrades by bond rating agencies have occurred. If either of the criteria regarding intent or requirement to sell is met, the entire difference between amortized cost and fair value is recognized as impairment through earnings. For debt securities that do not meet the aforementioned criteria, the amount of impairment is split into two components as follows: 1) OTTI related to credit loss, which must be recognized in the income statement, and 2) OTTI related to other factors, such as liquidity conditions in the market or changes in market interest rates, which is recognized in other comprehensive income. The credit loss is defined as the difference between the present value of the cash flows expected to be collected and the amortized cost.
	Loans: Loans that we have the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at the principal balance outstanding, net of deferred loan fees and costs and an allowance for loan losses. Interest income is accrued on the unpaid principal balance. Loan origination fees, net of certain direct origination costs, are deferred and recognized in interest income using the level-yield method without anticipating prepayments. Net unamortized deferred loan fees amounted to $1.1 million and $0.5 million at December 31, 2014 and 2013, respectively.
	Interest income on commercial loans and mortgage loans is discontinued at the time the loan is 90 days delinquent unless the loan is well-secured and in process of collection. Consumer and credit card loans are typically charged off no later than when they are 120 days past due. Past due status is based on the contractual terms of the loan. In all cases, loans are placed on nonaccrual or charged off at an earlier date if collection of principal and interest is considered doubtful.
	All interest accrued but not received for loans placed on nonaccrual is reversed against interest income. Interest received on such loans is accounted for on the cash-basis or cost-recovery method, until qualifying for return to accrual. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured.
	Loans Held for Sale: Mortgage loans originated and intended for sale in the secondary market are carried at the lower of aggregate cost or fair value, as determined by outstanding commitments from investors. Net unrealized losses, if any, are recorded as a valuation allowance and charged to earnings. Prior to the merger with Firstbank, such mortgage loans were sold servicing released. Subsequent to the merger, mortgage loans held for sale are generally sold with servicing rights retained. Gains and losses on sales of mortgage loans are based on the difference between the selling price and the carrying value of the related mortgage loan sold, which is reduced by the cost allocated to the servicing right. We generally lock in the sale price to the purchaser of the mortgage loan at the same time we make an interest rate commitment to the borrower.
	Year-end mortgage loans held for sale were as follows:
		2014		2013
	Mortgage loans held for sale	$	1,574,000	$	1,115,000
	Less: Allowance to adjust to lower of cost or market		0		0
	Mortgage loans held for sale, net	$	1,574,000	$	1,115,000
	Mortgage Loan Derivatives: From time to time, we enter into mortgage loan derivatives such as forward contracts and interest rate lock commitments in the ordinary course of business. The derivatives are not designated as hedges and are carried at fair value. The net gain or loss on mortgage loan derivatives is included in mortgage banking activities in the income statement. The balance of mortgage loan derivatives was immaterial at December 31, 2014 and 2013.
	Mortgage Banking Activities: Mortgage loan servicing rights are recognized as assets based on the allocated value of retained servicing rights on mortgage loans sold. Mortgage loan servicing rights are carried at the lower of amortized cost or fair value and are expensed in proportion to, and over the period of, estimated net servicing revenues. Impairment is evaluated based on the fair value of the rights using groupings of the underlying mortgage loans as to interest rates. Any impairment of a grouping is reported as a valuation allowance.
	Servicing fee income is recorded for fees earned for serving mortgage loans. The fees are based on a contractual percentage of the outstanding principal or a fixed amount per loan and are recorded as income when earned. Amortization of mortgage loan servicing rights is netted against mortgage loan servicing income and recorded in mortgage banking activities in the income statement.
	Troubled Debt Restructurings: A loan is accounted for as a troubled debt restructuring if we, for economic or legal reasons, grant a concession to a borrower considered to be experiencing financial difficulties that we would not otherwise consider. A troubled debt restructuring may involve the receipt of assets from the debtor in partial or full satisfaction of the loan, or a modification of terms such as a reduction of the stated interest rate or balance of the loan, a reduction of accrued interest, an extension of the maturity date or renewal of the loan at a stated interest rate lower than the current market rate for a new loan with similar risk, or some combination of these concessions. Troubled debt restructurings can be in either accrual or nonaccrual status. Nonaccrual troubled debt restructurings are included in nonperforming loans. Accruing troubled debt restructurings are generally excluded from nonperforming loans as it is considered probable that all contractual principal and interest due under the restructured terms will be collected.
	Loans modified as troubled debt restructurings are, by definition, considered to be impaired loans. Impairment for these loans is measured on a loan-by-loan basis similar to other impaired loans as described below under “Allowance for Loan Losses.” Certain loans modified as troubled debt restructurings may have been previously measured for impairment under a general allowance methodology (i.e., pooling), thus at the time the loan is modified as a troubled debt restructuring the allowance will be impacted by the difference between the results of these two measurement methodologies. Loans modified as troubled debt restructurings that subsequently default are factored into the determination of the allowance for loan losses in the same manner as other defaulted loans.
	Allowance for Loan Losses: The allowance for loan losses (“allowance”) is a valuation allowance for probable incurred credit losses. Loan losses are charged against the allowance when we believe the uncollectability of a loan is confirmed. Subsequent recoveries, if any, are credited to the allowance. We estimate the allowance balance required using past loan loss experience, the nature and volume of the loan portfolio, information about specific borrower situations and estimated collateral values, economic conditions and other factors. We estimate credit losses based on individual loans determined to be impaired and on all other loans grouped on similar risk characteristics. Our historical loss component is the most significant of the allowance components and is based on historical loss experience by credit risk grade for commercial loans and payment status for mortgage and consumer loans. Loans are pooled based on similar risk characteristics supported by observable data. The historical loss experience component of the allowance represents the results of migration analysis of historical net charge-offs for portfolios of loans, including groups of commercial loans within each credit risk grade. For measuring loss exposure in a pool of loans, the historical net charge-off or migration experience is utilized to estimate expected future losses to be realized from the pool of loans. Allocations of the allowance may be made for specific loans, but the entire allowance is available for any loan that, in our judgment, should be charged-off.
	A loan is considered impaired when, based on current information and events, it is probable we will be unable to collect the scheduled payments of principal and interest when due according to the contractual terms of the loan agreement. Factors considered in determining impairment include payment status and collateral value. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired. We determine the significance of payment delays and payment shortfalls on a case-by-case basis, taking into consideration all of the circumstances surrounding the loan and the borrower, including the length of delay, the reasons for delay, the borrower’s prior payment record and the amount of the shortfall in relation to the principal and interest owed. Impairment is measured on a loan-by-loan basis for commercial and construction loans by the present value of expected future cash flows discounted at the loan’s effective interest rate, the loan’s obtainable market price or the fair value of collateral if the loan is collateral dependent. Large groups of smaller balance homogeneous loans are collectively evaluated for impairment.
	Transfers of Financial Assets: Transfers of financial assets are accounted for as sales when control over the assets has been surrendered. Control over transferred assets is deemed to be surrendered when: (1) the assets have been isolated from the Bank and put presumptively beyond the reach of the transferor and its creditors, even in bankruptcy or other receivership, (2) the transferee obtains the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred assets, and (3) the Bank does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity or the ability to unilaterally cause the holder to return specific assets. Our transfers of financial assets are generally limited to commercial loan participations sold and residential mortgage loans sold in the secondary market.
	Premises and Equipment: Land is carried at cost. Premises and equipment are stated at cost less accumulated depreciation. Buildings and related components are depreciated using the straight-line method with useful lives ranging from 5 to 33 years. Furniture, fixtures and equipment are depreciated using the straight-line method with useful lives ranging from 3 to 7 years. Maintenance, repairs and minor alterations are charged to current operations as expenditures occur and major improvements are capitalized.
	Long-lived Assets: Premises and equipment and other long-lived assets are reviewed for impairment when events indicate their carrying amount may not be recoverable based on future undiscounted cash flows. If impaired, the assets are recorded at the lower of carrying value or fair value.
	Foreclosed Assets: Assets acquired through or in lieu of foreclosure are initially recorded at their estimated fair value net of estimated selling costs, establishing a new cost basis. If fair value subsequently declines, a valuation allowance is recorded through noninterest expense, as are collection and operating costs after acquisition. Foreclosed assets totaled $2.0 million and $2.9 million as of December 31, 2014 and 2013, respectively.
	Bank Owned Life Insurance: The Bank has purchased life insurance policies on certain key officers. Bank owned life insurance is recorded at its cash surrender value, or the amount that can be realized.
	Goodwill and Core Deposit Intangible: Goodwill results from business acquisitions and represents the excess of the purchase price over the fair value of acquired tangible assets and liabilities and identifiable intangible assets. Goodwill is assessed at least annually for impairment and any such impairment is recognized in the period identified. A more frequent assessment is performed should events or changes in circumstances indicate the carrying value of the goodwill may not be recoverable. We may elect to perform a qualitative assessment for the annual impairment test. If the qualitative assessment indicates it is more likely than not that the fair value of a reporting unit is less than its carrying amount, or if we elect not to perform a qualitative assessment, then we would be required to perform a quantitative test for goodwill impairment. The quantitative test is a two-step process consisting of comparing the carrying value of the reporting unit to an estimate of its fair value. If the estimated fair value of the reporting unit is less than the carrying value, goodwill is impaired and is written down to its estimated fair value. In 2014, we elected to perform a qualitative assessment for our annual impairment test and concluded our fair value was greater than its carrying amount; therefore, no further testing was required.
	The core deposit intangible that arose from the merger with Firstbank was initially measured at fair value and is being amortized into noninterest expense over a ten-year period using the sum-of-the-years-digits methodology.
	Repurchase Agreements: The Bank sells certain securities under agreements to repurchase. The agreements are treated as collateralized financing transactions, with the obligations to repurchase the securities sold reflected as liabilities and the securities underlying the agreements remaining in assets in the Consolidated Balance Sheets.
	Financial Instruments and Loan Commitments: Financial instruments include off-balance-sheet credit instruments, such as commitments to make loans and commercial letters of credit, issued to meet customer financing needs. The face amount for these items represents the exposure to loss, before considering customer collateral or ability to repay. Such financial instruments are recorded when they are funded. Instruments, such as standby letters of credit, that are considered financial guarantees are recorded at fair value.
	Stock-Based Compensation: Compensation cost for equity-based awards is measured on the grant date based on the fair value of the award at that date, and is recognized over the requisite service period, net of estimated forfeitures. Fair value of stock option awards is estimated using a closed option valuation (Black-Scholes) model. Fair value of restricted stock awards is based upon the quoted market price of the common stock on the date of grant.
	Advertising Costs: Advertising costs are expensed as incurred.
	Income Taxes: Income tax expense is the total of the current year income tax due or refundable, the change in deferred income tax assets and liabilities, and any adjustments related to unrecognized tax benefits. Deferred income tax assets and liabilities are recognized for the tax consequences of temporary differences between the carrying amounts and tax bases of assets and liabilities, computed using enacted tax rates applicable to future years. A valuation allowance, if needed, reduces deferred income tax assets to the amount expected to be realized.
	Fair Values of Financial Instruments: Fair values of financial instruments are estimated using relevant market information and other assumptions. Fair value estimates involve uncertainties and matters of significant judgment regarding interest rates, credit risk, prepayments and other factors, especially in the absence of broad markets for particular items. Changes in assumptions or in market conditions could significantly affect the estimates. The fair value estimates of existing on- and off-balance sheet financial instruments do not include the value of anticipated future business or the values of assets and liabilities not considered financial instruments.
	Earnings Per Share: Basic earnings per share is based on the weighted average number of common shares and participating securities outstanding during the period. Diluted earnings per share include the dilutive effect of additional potential common shares issuable under our stock-based compensation plans using the treasury stock method. In addition, diluted earnings per share for 2012 include the dilutive effect of our common stock warrant granted to the U.S. Department of Treasury that we repurchased on July 3, 2012, also using the treasury stock method. Our unvested stock awards, which contain non-forfeitable rights to dividends whether paid or unpaid (i.e., participating securities), are included in the number of shares outstanding for both basic and diluted earnings per share calculations. In the event of a net loss, our unvested stock awards are excluded from the calculations of both basic and diluted earnings per share.
	Comprehensive Income: Comprehensive income consists of net income and other comprehensive income (loss). Other comprehensive income (loss) includes unrealized gains and losses on securities available for sale and interest rate swaps which are also recognized as a separate component of equity.
	Derivatives: Derivative financial instruments are recognized as assets or liabilities at fair value. The accounting for changes in the fair value of derivatives depends on the use of the derivatives and whether the derivatives qualify for hedge accounting. Used as part of our asset and liability management to help manage interest rate risk, our derivatives have historically generally consisted of interest rate swap agreements that qualified for hedge accounting. We do not use derivatives for trading purposes.
	Changes in the fair value of derivatives that are designated, for accounting purposes, as a hedge of the variability of cash flows to be received on various assets and liabilities and are effective are reported in other comprehensive income. They are later reclassified into earnings in the same periods during which the hedged transaction affects earnings and are included in the line item in which the hedged cash flows are recorded. If hedge accounting does not apply, changes in the fair value of derivatives are recognized immediately in current earnings as interest income or expense.
	If designated as a hedge, we formally document the relationship between the derivative instrument and the hedged item, as well as the risk-management objective and the strategy for undertaking the hedge transaction. This documentation includes linking cash flow hedges to specific assets on the balance sheet. If designated as a hedge, we also formally assess, both at the hedge’s inception and on an ongoing basis, whether the derivative instrument that is used is highly effective in offsetting changes in cash flows of the hedged items. Ineffective hedge gains and losses are recognized immediately in current earnings as noninterest income or expense. We discontinue hedge accounting when we determine the derivative is no longer effective in offsetting changes in the cash flows of the hedged item, the derivative is settled or terminates, or treatment of the derivatives as a hedge is no longer appropriate or intended.
	Contingencies: Loss contingencies, including claims and legal actions arising in the ordinary course of business, are recorded as liabilities when the likelihood of loss is probable and an amount or range of loss can be reasonably estimated. We do not believe there are any such matters outstanding that would have a material effect on the financial statements.
	Reclassifications: Certain items in the prior years’ financial statements have been reclassified to conform to the current year presentation.
	Accounting Standards Updates: In January of 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-04, Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure. This ASU clarifies that an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. The ASU also requires additional related interim and annual disclosures. The guidance in this ASU is effective for annual and interim periods beginning after December 15, 2014, and is not expected to have a material effect on our financial position or results of operations when adopted.
	In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. This ASU establishes a comprehensive revenue recognition standard for virtually all industries under U.S. GAAP, including those that previously followed industry-specific guidance such as the real estate, construction and software industries. The revenue standard’s core principle is built on the contract between a vendor and a customer for the provision of goods and services. It attempts to depict the exchange of rights and obligations between the parties in the pattern of revenue recognition based on the consideration to which the vendor is entitled. To accomplish this objective, the standard requires five basic steps: i) identify the contract with the customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract, and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The guidance in this ASU is effective for annual and interim periods beginning after December 15, 2016, with three transition methods available – full retrospective, retrospective and cumulative effect approach. Although we are in process of evaluating the impact, the adoption of this ASU is not expected to have a material effect on our financial position or results of operations.
	In June 2014, the FASB issued ASU 2014-11, Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures. This ASU requires two accounting changes. First, repurchase-to-maturity transactions will be accounted for as secured borrowing transactions on the balance sheet, rather than sales. Second, for repurchase financing arrangements, the ASU requires separate accounting for a transfer of a financial asset executed contemporaneously with (or in contemplation of) a repurchase agreement with the same counterparty, which also will generally result in secured borrowing accounting for the repurchase agreement. The ASU also introduces new disclosures to increase transparency about the types of collateral pledged for repurchase agreements, securities lending transactions, and repurchase-to-maturity transactions that are accounted for as secured borrowings. The ASU also requires a transferor to disclose information about transactions accounted for as a sale in which the transferor retains substantially all of the exposure to the economic return on the transferred financial assets through an agreement with the transferee. The accounting changes and disclosure for certain transactions accounted for as a sale are effective for the first annual and interim periods beginning after December 15, 2014. The disclosure for transactions accounted for as secured borrowings is required for annual periods beginning after December 15, 2014, and for interim periods beginning after March 15, 2015. Adoption of this ASU is not expected to have a material effect on our financial position or results of operations.
	In August 2014, the FASB issued ASU 2014-14, Classification of Certain Government-Guaranteed Mortgage Loans Upon Foreclosure. This ASU requires that certain government-guaranteed mortgage loans, including those guaranteed by the Federal Housing Administration, be derecognized and that a separate other receivable be recognized upon foreclosure if certain conditions are met. Upon foreclosure on the loans that meet these criteria, a separate receivable should be recorded based on the amount of the loan balance expected to be recovered from the guarantor. The guidance in this ASU is effective for annual and interim periods beginning after December 15, 2014, and is not expected to have a material effect on our financial position or results of operations when adopted.

Note_2_Business_Combination

Note 2 - Business Combination	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	NOTE 2 - BUSINESS COMBINATION
	We completed the merger of Firstbank Corporation (“Firstbank”), a Michigan corporation with approximately $1.5 billion in total assets and 46 branch locations, into Mercantile Bank Corporation as of June 1, 2014 (“Merger Date”). Each share of Firstbank’s common stock was converted into the right to receive one share of Mercantile common stock, resulting in Mercantile issuing 8,087,272 shares of its common stock. The merger provided an expanded geographic footprint for the Company and increased the size of the balance sheet. In conjunction with the completion of the merger, Mercantile assumed the obligations of Firstbank Capital Trust I, Firstbank Capital Trust II, Firstbank Capital Trust III and Firstbank Capital Trust IV.
	The Firstbank transaction was accounted for using the acquisition method of accounting and accordingly, assets acquired, liabilities assumed and consideration exchanged were recorded at estimated fair value on the Merger Date. Preliminary goodwill of $49.5 million was calculated as the purchase premium after adjusting for the fair value of net assets acquired and represents the value expected from the synergies created from combining the two banking organizations as well as the economies of scale expected from combining the operations of the two companies. None of the goodwill is deductible for income tax purposes as the merger is accounted for as a tax-free exchange.
	The following table provides the purchase price calculation as of the Merger Date and the identifiable assets purchased and the liabilities assumed at their estimated fair values. These fair value measurements are provisional based on third-party valuations that are currently under review and are subject to refinement for up to one year after the Merger Date based on additional information that may be obtained by us that existed as of the Merger Date.
	Purchase Price:
	Mercantile common shares issued for Firstbank common shares		8,087,272
	Price per share, based on Mercantile closing price on May 30, 2014	$	21.43
	Value of common stock issued		173,310,000
	Value of replacement stock options granted		1,664,000
	Total purchase price	$	174,974,000
	Preliminary Statement of Net Assets Acquired at Fair Value:
	Assets
	Cash and cash equivalents	$	91,806,000
	Securities		358,599,000
	Total loans		943,662,000
	Premises and equipment		24,049,000
	Core deposit intangible		17,478,000
	Mortgage servicing rights		7,389,000
	Other assets		9,897,000
	Total Assets	$	1,452,880,000
	Liabilities
	Deposits	$	1,229,609,000
	Borrowings		87,615,000
	Other liabilities		10,155,000
	Total Liabilities	$	1,327,379,000
	Net Identifiable Assets Acquired			$	125,501,000
	Goodwill			$	49,473,000
	Effective December 31, 2014, we identified certain Firstbank deferred tax assets and liabilities that should have been addressed on the Merger Date. The net impact of recording the necessary entries was a $1.4 million reduction to Goodwill and a $1.4 million increase to our net deferred tax asset account (included in other assets above) from what we reported in our June 30, 2014 and September 30, 2014 Form 10-Qs.
	Firstbank’s results of operations prior to the Merger Date are not included in our Consolidated Statements of Income or Consolidated Statements of Comprehensive Income. We recorded merger-related expenses of $5.4 million and $1.2 million during 2014 and 2013, respectively. Such expenses were generally for professional services, costs related to termination of existing contractual arrangements for various services, retention and severance compensation costs, marketing and promotional expenses, travel costs, and printing and supplies costs. We do not expect to record any additional significant expenses related to the Firstbank merger in future periods. We are not presenting the amounts of revenue and earnings of Firstbank since the Merger Date as it is impracticable due to the integration of Firstbank upon the consummation of the merger.
	The following table provides the unaudited pro forma information for the results of operations for the twelve month periods ended December 31, 2014 and 2013, as if the acquisition had occurred on January 1, 2013. These adjustments reflect the impact of certain purchase accounting fair value measurements primarily related to Firstbank’s loan and deposit portfolios. In addition, the aggregate $12.2 million in merger-related expenses recorded by us and Firstbank during 2014 and 2013 are reflected to have been recorded during 2013. We expect to achieve further operating cost savings and other business synergies as a result of the merger which are not reflected in the pro forma amounts. These unaudited pro forma results are presented for illustrative purposes only and are not intended to represent or be indicative of the actual results of operations of the combined banking organization that would have been achieved had the merger occurred at the beginning of each period presented, nor are they intended to represent or be indicative of future results of operations.
		2014		2013
	Net interest income	$	98,607,000	$	93,862,000
	Noninterest expense		81,295,000		93,263,000
	Net income		22,659,000		16,068,000
	Net income per diluted share		1.33		0.96
	In most instances, determining the fair value of the acquired assets and assumed liabilities required us to estimate cash flows expected to result from those assets and liabilities and to discount those cash flows at appropriate rates of interest. The most significant of those determinations relates to the valuation of acquired loans. For such loans, the excess of cash flows expected at acquisition over the estimated fair value is recognized as interest income over the remaining lives of the loans. The difference between contractually required payments at acquisition and the cash flows expected to be collected at acquisition reflects the impact of estimated credit losses and other factors, such as prepayments. In accordance with the applicable accounting guidance for business combinations, there was no carry-over of Firstbank’s previously established allowance for loan losses.
	The acquired loans were divided into loans with evidence of credit quality deterioration, which are accounted for under ASC 310-30 (“acquired impaired”), and loans that do not meet this criteria, which are accounted for under ASC 310-20 (“acquired non-impaired”). In addition, the loans are further categorized into different loan pools based primarily on the type and purpose of the loan.
	The provisional fair value of loans at the Merger Date is presented in the following table:
		Acquired		Acquired		Acquired
		Impaired		Non-Impaired		Total Loans
	Commercial Loans:
	Commercial & industrial	$	878,000	$	163,316,000	$	164,194,000
	Commercial real estate		12,973,000		378,016,000		390,989,000
	Construction & development		1,289,000		33,726,000		35,015,000
	Total Commercial Loans	$	15,140,000	$	575,058,000	$	590,198,000
	Consumer Loans:
	Residential mortgages	$	9,694,000	$	216,653,000	$	226,347,000
	Instalment		167,000		61,657,000		61,824,000
	Home equity lines		288,000		52,054,000		52,342,000
	Construction		76,000		12,875,000		12,951,000
	Total Consumer Loans	$	10,225,000	$	343,239,000	$	353,464,000
	Total Loans	$	25,365,000	$	918,297,000	$	943,662,000
	The following table presents data on acquired impaired loans at the Merger Date:
		Acquired Impaired
	Contractually required payments	$	44,936,000
	Nonaccretable difference		17,057,000
	Expected cash flows		27,879,000
	Accretable yield		2,514,000
	Carrying balance	$	25,365,000
	The nonaccretable difference includes $10.4 million in principal cash flows not expected to be collected, $2.8 million of pre-acquisition charge-offs and $3.9 million of future interest not expected to be collected. The unpaid principal balance of acquired performing loans was $926.4 million at the Merger Date, and the unaccreted discount on such loans was $8.1 million.

Note_3_Securities

Note 3 - Securities	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]	NOTE 3 – SECURITIES
	The amortized cost and fair value of available for sale securities and the related gross unrealized gains and losses recognized in accumulated other comprehensive income (loss) were as follows:
					Gross		Gross
		Amortized			Unrealized		Unrealized			Fair
		Cost			Gains		Losses			Value
	2014
	U.S. Government agency debt obligations	$	194,894,000		$	1,612,000	$	(3,038,000	)	$	193,468,000
	Mortgage-backed securities		92,656,000			1,123,000		(218,000	)		93,561,000
	Municipal general obligation bonds		132,347,000			1,042,000		(307,000	)		133,082,000
	Municipal revenue bonds		10,769,000			117,000		(13,000	)		10,873,000
	Other investments		1,925,000			3,000		0			1,928,000
		$	432,591,000		$	3,897,000	$	(3,576,000	)	$	432,912,000
	2013
	U.S. Government agency debt obligations	$	108,279,000		$	263,000	$	(10,065,000	)	$	98,477,000
	Mortgage-backed securities		12,456,000			1,102,000		0			13,558,000
	Municipal general obligation bonds		16,488,000			388,000		(4,000	)		16,872,000
	Municipal revenue bonds		878,000			38,000		0			916,000
	Mutual funds		1,386,000			0		(31,000	)		1,355,000
		$	139,487,000		$	1,791,000	$	(10,100,000	)	$	131,178,000
	Securities with unrealized losses at year-end 2014 and 2013, aggregated by investment category and length of time that individual securities have been in a continuous loss position, are as follows:
		Less than 12 Months					12 Months or More					Total
		Fair			Unrealized		Fair			Unrealized		Fair		Unrealized
	Description of Securities	Value			Loss		Value			Loss		Value		Loss
	2014
	U.S. Government agency debt obligations	$	81,891,000		$	202,000	$	74,120,000		$	2,836,000	$	156,011,000	$	3,038,000
	Mortgage-backed securities		49,940,000			218,000		0			0		49,940,000		218,000
	Municipal general obligation bonds		54,104,000			307,000		0			0		54,104,000		307,000
	Municipal revenue bonds		4,644,000			13,000		0			0		4,644,000		13,000
	Other investments		0			0		0			0		0		0
		$	190,579,000		$	740,000	$	74,120,000		$	2,836,000	$	264,699,000	$	3,576,000
	2013
	U.S. Government agency debt obligations	$	57,117,000		$	5,798,000	$	29,679,000		$	4,267,000	$	86,796,000	$	10,065,000
	Mortgage-backed securities		0			0		0			0		0		0
	Municipal general obligation bonds		295,000			4,000		0			0		295,000		4,000
	Municipal revenue bonds		0			0		0			0		0		0
	Mutual funds		1,355,000			31,000		0			0		1,355,000		31,000
		$	58,767,000		$	5,833,000	$	29,679,000		$	4,267,000	$	88,446,000	$	10,100,000
	We evaluate securities for other-than-temporary impairment at least on a quarterly basis. Consideration is given to the length of time and the extent to which the fair value has been less than cost, the financial condition and near-term prospects of the issuer, and the intent and ability we have to retain our investment in the issuer for a period of time sufficient to allow for any anticipated recovery in fair value. For those debt securities whose fair value is less than their amortized cost basis, we also consider our intent to sell the security, whether it is more likely than not that we will be required to sell the security before recovery and if we do not expect to recover the entire amortized cost basis of the security. In analyzing an issuer’s financial condition, we may consider whether the securities are issued by the federal government or its agencies, whether downgrades by bond rating agencies have occurred and the results of reviews of the issuer’s financial condition.
	At December 31, 2014, 341 debt securities with fair values totaling $264.7 million have unrealized losses aggregating $3.6 million. After we considered whether the securities were issued by the federal government or its agencies and whether downgrades by bond rating agencies had occurred, we determined that unrealized losses were due to changing interest rate environments. As we do not intend to sell our debt securities before recovery of their cost basis and we believe it is more likely than not that we will not be required to sell our debt securities before recovery of the cost basis, no unrealized losses are deemed to be other-than-temporary.
	The amortized cost and fair values of debt securities at December 31, 2014, by maturity, are shown in the following table. The contractual maturity is utilized for U.S. Government agency debt obligations and municipal bonds. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Securities not due at a single maturity date, primarily mortgage-backed securities, are shown separately. Weighted average yields are also reflected, with yields for municipal securities shown at their tax equivalent yield.
		Weighted
		Average			Amortized		Fair
		Yield			Cost		Value
	Due in one year or less		0.72	%	$	27,651,000	$	27,662,000
	Due from one to five years		1.35			148,233,000		147,974,000
	Due from five to ten years		2.99			70,282,000		70,191,000
	Due after ten years		3.62			91,844,000		91,596,000
	Mortgage-backed securities		1.79			92,656,000		93,561,000
	Other investments		2.57			1,925,000		1,928,000
			2.17	%	$	432,591,000	$	432,912,000
	During 2013, Michigan Strategic Fund bonds totaling $10.3 million were sold at par. No securities were sold during 2014 and 2012.
	Securities issued by the State of Michigan and all its political subdivisions had a combined amortized cost of $113.1 million and $17.4 million at December 31, 2014 and December 31, 2013, respectively, with estimated market values of $113.9 million and $17.8 million, respectively. Securities issued by all other states and their political subdivisions had a combined amortized cost of $30.0 million and estimated market value of $30.0 million at December 31, 2014; as of December 31, 2013, our entire municipal bond portfolio consisted of securities issued by the State of Michigan and its political subdivisions. Total securities of any other specific issuer, other than the U.S. Government and its agencies and the State of Michigan and all its political subdivisions, did not exceed 10% of shareholders’ equity.
	The carrying value of U.S. Government agency debt obligations and mortgage-backed securities that are pledged to secure repurchase agreements was $180.5 million and $94.4 million at December 31, 2014 and 2013, respectively. In addition, substantially all of our municipal bonds have been pledged to the Discount Window of the Federal Reserve Bank of Chicago. Investments in FHLB stock are restricted and may only be resold to, or redeemed by, the issuer.

Note_4_Loans_and_Allowance_for

Note 4 - Loans and Allowance for Loan Losses	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Loans, Notes, Trade and Other Receivables Disclosure [Text Block]	NOTE 4 – LOANS AND ALLOWANCE FOR LOAN LOSSES
	Loans originated for investment are stated at their principal amount outstanding adjusted for partial charge-offs, the allowance, and net deferred loan fees and costs. Interest income on loans is accrued over the term of the loans primarily using the simple interest method based on the principal balance outstanding. Interest is not accrued on loans where collectability is uncertain. Accrued interest is included in other assets in the Consolidated Balance Sheets. Loan origination fees and certain direct costs incurred to extend credit are deferred and amortized over the term of the loan or loan commitment period as an adjustment to the related loan yield.
	Acquired loans are those purchased in the Firstbank merger (see Note 2 – Business Combination for further information). These loans were recorded at estimated fair value at the Merger Date with no carryover of the related allowance. The acquired loans were segregated between those considered to be performing (“acquired non-impaired loans”) and those with evidence of credit deterioration (“acquired impaired loans”). Acquired loans are considered impaired if there is evidence of credit deterioration and if it is probable, at acquisition, all contractually required payments will not be collected. Acquired loans restructured after acquisition are not considered or reported as troubled debt restructurings if the loans evidenced credit deterioration as of the Merger Date and are accounted for in pools.
	The fair value estimates for acquired loans are based on expected prepayments and the amount and timing of discounted expected principal, interest and other cash flows. Credit discounts representing the principal losses expected over the life of the loan are also a component of the initial fair value. In determining the Merger Date fair value of acquired impaired loans, and in subsequent accounting, we have generally aggregated acquired commercial and consumer loans into pools of loans with common risk characteristics.
	The difference between the fair value of an acquired non-impaired loan and contractual amounts due at the Merger Date is accreted into income over the estimated life of the loan. Contractually required payments represent the total undiscounted amount of all uncollected principal and interest payments. Acquired non-impaired loans are placed on nonaccrual status and reported as nonperforming or past due using the same criteria applied to the originated loan portfolio.
	The excess of an acquired impaired loan’s contractually required payments over the amount of its undiscounted cash flows expected to be collected is referred to as the non-accretable difference. The non-accretable difference, which is neither accreted into income nor recorded on the Consolidated Balance Sheets, reflects estimated future credit losses and uncollectable contractual interest expected to be incurred over the life of the acquired impaired loan. The excess cash flows expected to be collected over the carrying amount of the acquired loan is referred to as the accretable yield. This amount is accreted into interest income over the remaining life of the acquired loans or pools using the level yield method. The accretable yield is affected by changes in interest rate indices for variable rate loans, changes in prepayment speed assumptions and changes in expected principal and interest payments over the estimated lives of the acquired impaired loans.
	We evaluate quarterly the remaining contractually required payments receivable and estimate cash flows expected to be collected over the lives of the impaired loans. Contractually required payments receivable may increase or decrease for a variety of reasons, for example, when the contractual terms of the loan agreement are modified, when interest rates on variable rate loans change, or when principal and/or interest payments are received. Cash flows expected to be collected on acquired impaired loans are estimated by incorporating several key assumptions similar to the initial estimate of fair value. These key assumptions include probability of default, loss given default, and the amount of actual prepayments after the Merger Date. Prepayments affect the estimated lives of loans and could change the amount of interest income, and possibly principal, expected to be collected. In re-forecasting future estimated cash flows, credit loss expectations are adjusted as necessary. The adjustments are based, in part, on actual loss severities recognized for each loan type, as well as changes in the probability of default. For periods in which estimated cash flows are not re-forecasted, the prior reporting period’s estimated cash flows are adjusted to reflect the actual cash received and credit events that transpired during the current reporting period.
	Increases in expected cash flows of acquired impaired loans subsequent to the Merger Date are recognized prospectively through adjustments of the yield on the loans or pools over their remaining lives, while decreases in expected cash flows are recognized as impairment through a provision for loan losses and an increase in the allowance.
	Year-end loans disaggregated by class of loan within the loan portfolio segments were as follows:
														Percent
		31-Dec-14						31-Dec-13						Increase
		Balance			%			Balance			%			(Decrease)
	Originated Loans
	Commercial:
	Commercial and industrial	$	384,570,000			30.8	%	$	286,373,000			27.2	%		34.3	%
	Vacant land, land development, and residential construction		29,826,000			2.4			36,741,000			3.5			(18.8	)
	Real estate – owner occupied		291,758,000			23.4			261,877,000			24.9			11.4
	Real estate – non-owner occupied		410,977,000			33			364,066,000			34.6			12.9
	Real estate – multi-family and residential rental		36,058,000			2.9			37,639,000			3.5			(4.2	)
	Total commercial		1,153,189,000			92.5			986,696,000			93.7			16.9
	Retail:
	Home equity and other		50,059,000			4			35,080,000			3.3			42.7
	1-4 family mortgages		42,868,000			3.5			31,467,000			3			36.2
	Total retail		92,927,000			7.5			66,547,000			6.3			39.6
	Total originated loans	$	1,246,116,000			100	%	$	1,053,243,000			100	%		18.3	%
														Percent
		31-Dec-14						31-Dec-13						Increase
		Balance			%			Balance			%			(Decrease)
	Acquired Loans
	Commercial:
	Commercial and industrial	$	166,037,000			19.7	%	$	0			NA			NM
	Vacant land, land development, and residential construction		22,148,000			2.6			0			NA			NM
	Real estate – owner occupied		138,630,000			16.4			0			NA			NM
	Real estate – non-owner occupied		148,597,000			17.6			0			NA			NM
	Real estate – multi-family and residential rental		86,702,000			10.3			0			NA			NM
	Total commercial		562,114,000			66.6			0			NA			NM
	Retail:
	Home equity and other		109,219,000			13			0			NA			NM
	1-4 family mortgages		171,828,000			20.4			0			NA			NM
	Total retail		281,047,000			33.4			0			NA			NM
	Total acquired loans	$	843,161,000			100	%	$	0			NA			NM
														Percent
		31-Dec-14						31-Dec-13						Increase
		Balance			%			Balance			%			(Decrease)
	Total Loans
	Commercial:
	Commercial and industrial	$	550,607,000			26.4	%	$	286,373,000			27.2	%		92.3	%
	Vacant land, land development, and residential construction		51,974,000			2.5			36,741,000			3.5			41.5
	Real estate – owner occupied		430,388,000			20.5			261,877,000			24.9			64.3
	Real estate – non-owner occupied		559,574,000			26.8			364,066,000			34.6			53.7
	Real estate – multi-family and residential rental		122,760,000			5.9			37,639,000			3.5			226.2
	Total commercial		1,715,303,000			82.1			986,696,000			93.7			73.8
	Retail:
	Home equity and other		159,278,000			7.6			35,080,000			3.3			354
	1-4 family mortgages		214,696,000			10.3			31,467,000			3			582.3
	Total retail		373,974,000			17.9			66,547,000			6.3			462
	Total loans	$	2,089,277,000			100	%	$	1,053,243,000			100	%		98.4	%
	The total contractually required payments and carrying value of acquired impaired loans was $31.4 million and $18.6 million, respectively, as of December 31, 2014. Changes in the accretable yield for acquired impaired loans for the seven-month period ended December 31, 2014 were as follows:
		2014
	Balance at May 31, 2014	$	0
	Additions		2,514,000
	Accretion		(786,000	)
	Net reclassification from nonaccretable to accretable		3,537,000
	Disposals		(40,000	)
Other activity		(227,000	)
Balance at December 31, 2014	$	4,998,000
Concentrations within the loan portfolio were as follows at year-end:
	2014						2013
				Percentage of						Percentage of
	Balance			Loan Portfolio			Balance			Loan Portfolio
Commercial real estate loans to lessors of non-residential buildings	$	480,170,000			23	%	$	299,446,000			28.4	%
Year-end nonperforming originated loans were as follows:
	2014			2013
Loans past due 90 days or more still accruing interest	$	0		$	0
Nonaccrual loans		26,048,000			6,718,000
Total nonperforming loans	$	26,048,000		$	6,718,000
Year-end nonperforming acquired loans were as follows:
	2014			2013
Loans past due 90 days or more still accruing interest	$	26,000		$	NA
Nonaccrual loans		3,358,000			NA
Total nonperforming loans	$	3,384,000		$	NA
The recorded principal balance of nonperforming loans was as follows:
	December 31,			December 31,
	2014			2013
Commercial:
Commercial and industrial	$	6,478,000		$	1,501,000
Vacant land, land development, and residential construction		209,000			785,000
Real estate – owner occupied		18,062,000			389,000
Real estate – non-owner occupied		378,000			168,000
Real estate – multi-family and residential rental		106,000			208,000
Total commercial		25,233,000			3,051,000
Retail:
Home equity and other		800,000			788,000
1-4 family mortgages		3,399,000			2,879,000
Total retail		4,199,000			3,667,000
Total nonperforming loans	$	29,432,000		$	6,718,000
Acquired impaired loans are not reported as nonperforming loans based on acquired impaired loan accounting. Acquired non-impaired loans are placed on nonaccrual status and reported as nonperforming or past due using the same criteria applied to the originated loan portfolio.
An age analysis of past due loans is as follows as of December 31, 2014:
							Greater											Recorded
	30 – 59			60 – 89			Than 89											Balance > 89
	Days			Days			Days			Total						Total		Days and
	Past Due			Past Due			Past Due			Past Due			Current			Loans		Accruing
Originated Loans
Commercial:
Commercial and industrial	$	0		$	0		$	0		$	0		$	384,570,000		$	384,570,000	$	0
Vacant land, land development, and residential construction		0			0			0			0			29,826,000			29,826,000		0
Real estate – owner occupied		0			0			120,000			120,000			291,638,000			291,758,000		0
Real estate – non-owner occupied		0			0			116,000			116,000			410,861,000			410,977,000		0
Real estate – multi-family and residential rental		0			0			0			0			36,058,000			36,058,000		0
Total commercial		0			0			236,000			236,000			1,152,953,000			1,153,189,000		0
Retail:
Home equity and other		38,000			3,000			0			41,000			50,018,000			50,059,000		0
1- 4 family mortgages		0			0			366,000			366,000			42,502,000			42,868,000		0
Total retail		38,000			3,000			366,000			407,000			92,520,000			92,927,000		0
Total past due loans	$	38,000		$	3,000		$	602,000		$	643,000		$	1,245,473,000		$	1,246,116,000	$	0
							Greater											Recorded
	30 – 59			60 – 89			Than 89											Balance > 89
	Days			Days			Days			Total						Total		Days and
	Past Due			Past Due			Past Due			Past Due			Current			Loans		Accruing
Acquired Loans
Commercial:
Commercial and industrial	$	29,000		$	32,000		$	76,000		$	137,000		$	165,900,000		$	166,037,000	$	0
Vacant land, land development, and residential construction		0			38,000			0			38,000			22,110,000			22,148,000		0
Real estate – owner occupied		51,000			425,000			1,625,000			2,101,000			136,529,000			138,630,000		0
Real estate – non-owner occupied		68,000			598,000			395,000			1,061,000			147,536,000			148,597,000		0
Real estate – multi-family and residential rental		37,000			0			105,000			142,000			86,560,000			86,702,000		0
Total commercial		185,000			1,093,000			2,201,000			3,479,000			558,635,000			562,114,000		0
Retail:
Home equity and other		445,000			419,000			155,000			1,019,000			108,200,000			109,219,000		26,000
1- 4 family mortgages		1,087,000			408,000			750,000			2,245,000			169,583,000			171,828,000		0
Total retail		1,532,000			827,000			905,000			3,264,000			277,783,000			281,047,000		26,000
Total past due loans	$	1,717,000		$	1,920,000		$	3,106,000		$	6,743,000		$	836,418,000		$	843,161,000	$	26,000
An age analysis of past due loans is as follows as of December 31, 2013:
							Greater											Recorded
	30 – 59			60 – 89			Than 89											Balance > 89
	Days			Days			Days			Total						Total		Days and
	Past Due			Past Due			Past Due			Past Due			Current			Loans		Accruing
Originated Loans
Commercial:
Commercial and industrial	$	0		$	0		$	309,000		$	309,000		$	286,064,000		$	286,373,000	$	0
Vacant land, land development, and residential construction		0			0			0			0			36,741,000			36,741,000		0
Real estate – owner occupied		65,000			0			50,000			115,000			261,762,000			261,877,000		0
Real estate – non-owner occupied		0			0			0			0			364,066,000			364,066,000		0
Real estate – multi-family and residential rental		0			0			64,000			64,000			37,575,000			37,639,000		0
Total commercial		65,000			0			423,000			488,000			986,208,000			986,696,000		0
Retail:
Home equity and other		14,000			0			0			14,000			35,066,000			35,080,000		0
1- 4 family mortgages		21,000			44,000			375,000			440,000			31,027,000			31,467,000		0
Total retail		35,000			44,000			375,000			454,000			66,093,000			66,547,000		0
Total past due loans	$	100,000		$	44,000		$	798,000		$	942,000		$	1,052,301,000		$	1,053,243,000	$	0
Impaired originated loans with no related allowance recorded were as follows as of December 31, 2014:
										Year-To-Date
	Unpaid									Average
	Contractual			Recorded						Recorded
	Principal			Principal			Related			Principal
	Balance			Balance			Allowance			Balance
With no related allowance recorded:
Commercial:
Commercial and industrial	$	1,170,000		$	1,164,000					$	652,000
Vacant land, land development and residential construction		540,000			209,000						227,000
Real estate – owner occupied		3,609,000			1,901,000						4,365,000
Real estate – non-owner occupied		1,210,000			1,210,000						971,000
Real estate – multi-family and residential rental		375,000			317,000						64,000
Total commercial		6,904,000			4,801,000						6,279,000
Retail:
Home equity and other		207,000			191,000						517,000
1-4 family mortgages		1,144,000			560,000						585,000
Total retail		1,351,000			751,000						1,102,000
Total with no related allowance recorded	$	8,255,000		$	5,552,000			0		$	7,381,000
Impaired originated loans with an allowance recorded and total impaired loans were as follows as of December 31, 2014:
										Year-To-Date
	Unpaid									Average
	Contractual			Recorded						Recorded
	Principal			Principal			Related			Principal
	Balance			Balance			Allowance			Balance
With an allowance recorded:
Commercial:
Commercial and industrial	$	5,299,000		$	5,226,000		$	1,578,000		$	2,759,000
Vacant land, land development and residential construction		2,000,000			2,000,000			151,000			3,229,000
Real estate – owner occupied		15,745,000			15,674,000			2,200,000			4,630,000
Real estate – non-owner occupied		16,033,000			15,949,000			4,779,000			18,245,000
Real estate – multi-family and residential rental		1,371,000			1,371,000			666,000			1,700,000
Total commercial		40,448,000			40,220,000			9,374,000			30,563,000
Retail:
Home equity and other		115,000			84,000			84,000			128,000
1-4 family mortgages		2,194,000			2,000,000			694,000			2,115,000
Total retail		2,309,000			2,084,000			778,000			2,243,000
Total with an allowance recorded	$	42,757,000		$	42,304,000		$	10,152,000		$	32,806,000
Total impaired loans:
Commercial	$	47,352,000		$	45,021,000		$	9,374,000		$	36,842,000
Retail		3,660,000			2,835,000			778,000			3,345,000
Total impaired loans	$	51,012,000		$	47,856,000		$	10,152,000		$	40,187,000
Impaired acquired loans with no related allowance recorded were as follows as of December 31, 2014:
										Year-To-Date
	Unpaid									Average
	Contractual			Recorded						Recorded
	Principal			Principal			Related			Principal
	Balance			Balance			Allowance			Balance
With no related allowance recorded:
Commercial:
Commercial and industrial	$	1,586,000		$	1,579,000					$	563,000
Vacant land, land development and residential construction		0			0						0
Real estate – owner occupied		113,000			113,000						52,000
Real estate – non-owner occupied		326,000			326,000						260,000
Real estate – multi-family and residential rental		487,000			487,000						166,000
Total commercial		2,512,000			2,505,000						1,041,000
Retail:
Home equity and other		641,000			639,000						262,000
1-4 family mortgages		866,000			866,000						458,000
Total retail		1,507,000			1,505,000						720,000
Total with no related allowance recorded	$	4,019,000		$	4,010,000			0		$	1,761,000
Impaired acquired loans with an allowance recorded and total impaired loans were as follows as of December 31, 2014:
										Year-To-Date
	Unpaid									Average
	Contractual			Recorded						Recorded
	Principal			Principal			Related			Principal
	Balance			Balance			Allowance			Balance
With an allowance recorded:
Commercial:
Commercial and industrial	$	0		$	0		$	0		$	0
Vacant land, land development and residential construction		0			0			0			0
Real estate – owner occupied		1,516,000			1,502,000			605,000			501,000
Real estate – non-owner occupied		0			0			0			0
Real estate – multi-family and residential rental		0			0			0			0
Total commercial		1,516,000			1,502,000			605,000			501,000
Retail:
Home equity and other		0			0			0			0
1-4 family mortgages		0			0			0			0
Total retail		0			0			0			0
Total with an allowance recorded	$	1,516,000		$	1,502,000		$	605,000		$	501,000
Total impaired loans:
Commercial	$	4,028,000		$	4,007,000		$	605,000		$	1,542,000
Retail		1,507,000			1,505,000			0			720,000
Total impaired loans	$	5,535,000		$	5,512,000		$	605,000		$	2,262,000
Impaired originated loans with no related allowance recorded were as follows as of December 31, 2013:
										Year-To-Date
	Unpaid									Average
	Contractual			Recorded						Recorded
	Principal			Principal			Related			Principal
	Balance			Balance			Allowance			Balance
With no related allowance recorded:
Commercial:
Commercial and industrial	$	2,229,000		$	511,000					$	1,205,000
Vacant land, land development and residential construction		475,000			362,000						991,000
Real estate – owner occupied		1,270,000			785,000						1,084,000
Real estate – non-owner occupied		895,000			733,000						4,049,000
Real estate – multi-family and residential rental		41,000			1,000						390,000
Total commercial		4,910,000			2,392,000						7,719,000
Retail:
Home equity and other		507,000			461,000						471,000
1-4 family mortgages		1,272,000			647,000						727,000
Total retail		1,779,000			1,108,000						1,198,000
Total with no related allowance recorded	$	6,689,000		$	3,500,000			0		$	8,917,000
Impaired originated loans with an allowance recorded and total impaired loans were as follows as of December 31, 2013:
										Year-To-Date
	Unpaid									Average
	Contractual			Recorded						Recorded
	Principal			Principal			Related			Principal
	Balance			Balance			Allowance			Balance
With an allowance recorded:
Commercial:
Commercial and industrial	$	1,517,000		$	1,440,000		$	792,000		$	1,880,000
Vacant land, land development and residential construction		4,436,000			4,139,000			844,000			3,354,000
Real estate – owner occupied		1,513,000			1,513,000			528,000			2,550,000
Real estate – non-owner occupied		21,088,000			21,072,000			7,969,000			28,388,000
Real estate – multi-family and residential rental		3,219,000			2,684,000			1,127,000			2,915,000
Total commercial		31,773,000			30,848,000			11,260,000			39,087,000
Retail:
Home equity and other		320,000			289,000			96,000			329,000
1-4 family mortgages		2,274,000			2,231,000			1,030,000			1,628,000
Total retail		2,594,000			2,520,000			1,126,000			1,957,000
Total with an allowance recorded	$	34,367,000		$	33,368,000		$	12,386,000		$	41,044,000
Total impaired loans:
Commercial	$	36,683,000		$	33,240,000		$	11,260,000		$	46,806,000
Retail		4,373,000			3,628,000			1,126,000			3,155,000
Total impaired loans	$	41,056,000		$	36,868,000		$	12,386,000		$	49,961,000
Impaired loans for which no allocation of the allowance for loan losses has been made generally reflect situations whereby the loans have been charged-down to estimated collateral value. Interest income recognized on accruing troubled debt restructurings totaled $1.8 million, $2.5 million and $2.0 million during 2014, 2013 and 2012, respectively. Interest income recognized on nonaccrual loans totaled $1.9 million during 2013, reflecting the collection of interest at the time of principal pay-off. No such significant collections of interest income were recorded during 2014 or 2012. Lost interest income on nonaccrual loans totaled $0.1 million, $0.4 million and $0.8 million during 2014, 2013 and 2012, respectively.
Credit Quality Indicators. We utilize a comprehensive grading system for our commercial loans. All commercial loans are graded on a ten grade rating system. The rating system utilizes standardized grade paradigms that analyze several critical factors such as cash flow, operating performance, financial condition, collateral, industry condition and management. All commercial loans are graded at inception and reviewed and, if appropriate, re-graded at various intervals thereafter. The risk assessment for retail loans is primarily based on the type of collateral and payment activity.
Loans by credit quality indicators were as follows as of December 31, 2014:
Originated Loans
Commercial credit exposure – credit risk profiled by internal credit risk grades:
	Commercial			Commercial			Commercial			Commercial			Commercial
	and			Vacant Land, Land			Real Estate -			Real Estate -			Real Estate -
	Industrial			Development,			Owner			Non-Owner			Multi-Family
				and Residential			Occupied			Occupied			and Residential
				Construction									Rental
Internal credit risk grade groupings:
Grades 1 – 4	$	266,631,000		$	11,242,000		$	190,656,000		$	285,035,000		$	12,394,000
Grades 5 – 7		109,639,000			16,375,000			83,123,000			113,982,000			22,282,000
Grades 8 – 9		8,300,000			2,209,000			17,979,000			11,960,000			1,382,000
Total commercial	$	384,570,000		$	29,826,000		$	291,758,000		$	410,977,000		$	36,058,000
Retail credit exposure – credit risk profiled by collateral type:
	Retail			Retail
	Home Equity			1-4 Family
	and Other			Mortgages
Total retail	$	50,059,000		$	42,868,000
Acquired Loans
Commercial credit exposure – credit risk profiled by internal credit risk grades:
				Commercial									Commercial
				Vacant Land,			Commercial			Commercial			Real Estate -
	Commercial			Land Development,			Real Estate -			Real Estate -			Multi-Family
	and			and Residential			Owner			Non-Owner			and Residential
	Industrial			Construction			Occupied			Occupied			Rental
Internal credit risk grade groupings:
Grades 1 – 4	$	72,411,000		$	5,875,000		$	39,496,000		$	65,886,000		$	35,858,000
Grades 5 – 7		90,320,000			14,472,000			92,212,000			78,103,000			49,781,000
Grades 8 – 9		3,306,000			1,801,000			6,922,000			4,608,000			1,063,000
Total commercial	$	166,037,000		$	22,148,000		$	138,630,000		$	148,597,000		$	86,702,000
Retail credit exposure – credit risk profiled by collateral type:
	Retail			Retail
	Home Equity			1-4 Family
	and Other			Mortgages
Total retail	$	109,219,000		$	171,828,000
Loans by credit quality indicators were as follows as of December 31, 2013:
Originated Loans
Commercial credit exposure – credit risk profiled by internal credit risk grades:
				Commercial Vacant Land, Land			Commercial			Commercial			Commercial Real Estate -
	Commercial			Development,			Real Estate -			Real Estate -			Multi-Family
	and			and Residential			Owner			Non-Owner			and Residential
	Industrial			Construction			Occupied			Occupied			Rental
Internal credit risk grade groupings:
Grades 1 – 4	$	208,151,000		$	6,973,000		$	156,230,000		$	219,325,000		$	15,465,000
Grades 5 – 7		76,237,000			25,535,000			103,066,000			122,717,000			19,469,000
Grades 8 – 9		1,985,000			4,233,000			2,581,000			22,024,000			2,705,000
Total commercial	$	286,373,000		$	36,741,000		$	261,877,000		$	364,066,000		$	37,639,000
Retail credit exposure – credit risk profiled by collateral type:
	Retail			Retail
	Home Equity			1-4 Family
	and Other			Mortgages
Total retail	$	35,080,000		$	31,467,000
All commercial loans are graded using the following number system:
Grade 1.     Excellent credit rating that contain very little, if any, risk of loss.
Grade 2.     Strong sources of repayment and have low repayment risk.
Grade 3.     Good sources of repayment and have limited repayment risk.
Grade 4.     Adequate sources of repayment and acceptable repayment risk; however, characteristics are present that render the credit more vulnerable to a negative event.
Grade 5.     Marginally acceptable sources of repayment and exhibit defined weaknesses and negative characteristics.
Grade 6.     Well defined weaknesses which may include negative current cash flow, high leverage, or operating losses. Generally, if the credit does not stabilize or if further deterioration is observed in the near term, the loan will likely be downgraded and placed on the Watch List (i.e., list of lending relationships that receive increased scrutiny and review by the Board of Directors and senior management).
Grade 7.     Defined weaknesses or negative trends that merit close monitoring through Watch List status.
Grade 8.     Inadequately protected by current sound net worth, paying capacity of the obligor, or pledged collateral, resulting in a distinct possibility of loss requiring close monitoring through Watch List status.
Grade 9.     Vital weaknesses exist where collection of principal is highly questionable.
Grade 10.   Considered uncollectable and of such little value that their continuance as an asset is not warranted.
The primary risk elements with respect to commercial loans are the financial condition of the borrower, the sufficiency of collateral, and timeliness of scheduled payments. We have a policy of requesting and reviewing periodic financial statements from commercial loan customers and employ a disciplined and formalized review of the existence of collateral and its value. The primary risk element with respect to each residential real estate loan and consumer loan is the timeliness of scheduled payments. We have a reporting system that monitors past due loans and have adopted policies to pursue creditor’s rights in order to preserve our collateral position.
The allowance for originated loan losses and recorded investments in originated loans for the year-ended December 31, 2014 are as follows:
	Commercial			Retail
	Loans			Loans			Unallocated			Total
Allowance for loan losses:
Beginning balance	$	20,455,000		$	2,358,000		$	8,000		$	22,821,000
Provision for loan losses		(3,140,000	)		(721,000	)		68,000			(3,793,000	)
Charge-offs		(876,000	)		(554,000	)		0			(1,430,000	)
Recoveries		1,297,000			404,000			0			1,701,000
Ending balance	$	17,736,000		$	1,487,000		$	76,000		$	19,299,000
Ending balance: individually evaluated for impairment	$	9,374,000		$	777,000		$	0		$	10,151,000
Ending balance: collectively evaluated for impairment	$	8,362,000		$	710,000		$	76,000		$	9,148,000
Total loans:
Ending balance	$	1,153,189,000		$	92,927,000					$	1,246,116,000
Ending balance: individually evaluated for impairment	$	45,021,000		$	2,835,000					$	47,856,000
Ending balance: collectively evaluated for impairment	$	1,108,168,000		$	90,092,000					$	1,198,260,000
The allowance for acquired loan losses for the year-ended December 31, 2014 is as follows:
	Commercial			Retail
	Loans			Loans			Unallocated			Total
Allowance for loan losses:
Beginning balance	$	0		$	0		$	0		$	0
Provision for loan losses		734,000			59,000			0			793,000
Charge-offs		(55,000	)		(16,000	)		0			(71,000	)
Recoveries		2,000			18,000			0			20,000
Ending balance	$	681,000		$	61,000		$	0		$	742,000
In accordance with the applicable accounting guidance for business combinations, there was no carry-over of Firstbank’s previously established allowance for loan losses.
The allowance for loan losses and recorded investments in loans for the year-ended December 31, 2013 are as follows:
	Commercial			Retail
	Loans			Loans			Unallocated			Total
Allowance for loan losses:
Beginning balance	$	26,043,000		$	2,645,000		$	(11,000	)	$	28,677,000
Provision for loan losses		(6,730,000	)		(489,000	)		19,000			(7,200,000	)
Charge-offs		(5,120,000	)		(170,000	)		0			(5,290,000	)
Recoveries		6,262,000			372,000			0			6,634,000
Ending balance	$	20,455,000		$	2,358,000		$	8,000		$	22,821,000
Ending balance: individually evaluated for impairment	$	11,260,000		$	1,126,000		$	0		$	12,386,000
Ending balance: collectively evaluated for impairment	$	9,195,000		$	1,232,000		$	8,000		$	10,435,000
Total loans:
Ending balance	$	986,696,000		$	66,547,000					$	1,053,243,000
Ending balance: individually evaluated for impairment	$	33,240,000		$	3,628,000					$	36,868,000
Ending balance: collectively evaluated for impairment	$	953,456,000		$	62,919,000					$	1,016,375,000
The allowance for loan losses and recorded investments in loans for the year-ended December 31, 2012 are as follows:
	Commercial			Retail
	Loans			Loans			Unallocated			Total
Allowance for loan losses:
Beginning balance	$	33,431,000		$	3,019,000		$	82,000		$	36,532,000
Provision for loan losses		(2,800,000	)		(207,000	)		(93,000	)		(3,100,000	)
Charge-offs		(12,075,000	)		(569,000	)		0			(12,644,000	)
Recoveries		7,487,000			402,000			0			7,889,000
Ending balance	$	26,043,000		$	2,645,000		$	(11,000	)	$	28,677,000
Ending balance: individually evaluated for impairment	$	16,860,000		$	329,000		$	0		$	17,189,000
Ending balance: collectively evaluated for impairment	$	9,183,000		$	2,316,000		$	(11,000	)	$	11,488,000
Total loans:
Ending balance	$	968,506,000		$	72,683,000					$	1,041,189,000
Ending balance: individually evaluated for impairment	$	55,138,000		$	2,141,000					$	57,279,000
Ending balance: collectively evaluated for impairment	$	913,368,000		$	70,542,000					$	983,910,000
Loans modified as troubled debt restructurings during 2014 were as follows:
				Pre-			Post-
				Modification			Modification
				Recorded			Recorded
	Number of			Principal			Principal
	Contracts			Balance			Balance
Originated Loans
Commercial:
Commercial and industrial		2		$	5,994,000		$	6,094,000
Vacant land, land development and residential construction		0			0			0
Real estate – owner occupied		2			16,787,000			16,787,000
Real estate – non-owner occupied		1			146,000			146,000
Real estate – multi-family and residential rental		0			0			0
Total commercial		5			22,927,000			23,027,000
Retail:
Home equity and other		0			0			0
1-4 family mortgages		0			0			0
Total retail		0			0			0
Total		5		$	22,927,000		$	23,027,000
Acquired Loans
Commercial:
Commercial and industrial		7		$	1,604,000		$	1,604,000
Vacant land, land development and residential construction		0			0			0
Real estate – owner occupied		2			1,619,000			1,619,000
Real estate – non-owner occupied		1			65,000			65,000
Real estate – multi-family and residential rental		4			394,000			394,000
Total commercial		14			3,682,000			3,682,000
Retail:
Home equity and other		1			26,000			26,000
1-4 family mortgages		1			179,000			179,000
Total retail		2			205,000			205,000
Total		16		$	3,887,000		$	3,887,000
Originated loans modified as troubled debt restructurings during 2013 were as follows:
				Pre-			Post-
				Modification			Modification
				Recorded			Recorded
	Number of			Principal			Principal
	Contracts			Balance			Balance
Commercial:
Commercial and industrial		3		$	741,000		$	741,000
Vacant land, land development and residential construction		2			3,610,000			3,610,000
Real estate – owner occupied		2			715,000			715,000
Real estate – non-owner occupied		1			45,000			45,000
Real estate – multi-family and residential rental		1			241,000			241,000
Total commercial		9			5,352,000			5,352,000
Retail:
Home equity and other		0			0			0
1-4 family mortgages		1			1,879,000			1,879,000
Total retail		1			1,879,000			1,879,000
Total		10		$	7,231,000		$	7,231,000
The following originated loans, modified as troubled debt restructurings within the previous twelve months, became over 30 days past due during the twelve months ended December 31, 2014 (amounts as of period end):
				Recorded
	Number of			Principal
	Contracts			Balance
Commercial:
Commercial and industrial		0		$	0
Vacant land, land development and residential construction		0			0
Real estate – owner occupied		0			0
Real estate – non-owner occupied		0			0
Real estate – multi-family and residential rental		0			0
Total commercial		0			0
Retail:
Home equity and other		0			0
1-4 family mortgages		0			0
Total retail		0			0
Total		0		$	0
The following acquired loans, modified as troubled debt restructurings within the previous seven months, became over 30 days past due during the seven months ended December 31, 2014 (amounts as of period end):
				Recorded
	Number of			Principal
	Contracts			Balance
Commercial:
Commercial and industrial		0		$	0
Vacant land, land development and residential construction		0			0
Real estate – owner occupied		0			0
Real estate – non-owner occupied		0			0
Real estate – multi-family and residential rental		0			0
Total commercial		0			0
Retail:
Home equity and other		0			0
1-4 family mortgages		0			0
Total retail		0			0
Total		0		$	0
The following originated loans, modified as troubled debt restructurings within the previous twelve months, became over 30 days past due during the twelve months ended December 31, 2013 (amounts as of period end):
	Number of			Principal
	Contracts			Balance
Commercial:
Commercial and industrial		0		$	0
Vacant land, land development and residential construction		0			0
Real estate – owner occupied		1			65,000
Real estate – non-owner occupied		0			0
Real estate – multi-family and residential rental		0			0
Total commercial		1			65,000
Retail:
Home equity and other		0			0
1-4 family mortgages		0			0
Total retail		0			0
Total		1		$	65,000
Activity for originated loans categorized as troubled debt restructurings during 2014 is as follows:
				Commercial
				Vacant Land,			Commercial			Commercial			Commercial
				Land									Real Estate -
	Commercial			Development,			Real Estate -			Real Estate -			Multi-Family
	and			and Residential			Owner			Non-Owner			and Residential
	Industrial			Construction			Occupied			Occupied			Rental
Commercial Loan Portfolio:
Beginning Balance	$	1,656,000		$	4,501,000		$	1,816,000		$	22,311,000		$	2,620,000
Charge-Offs		(67,000	)		0			(11,000	)		0			(420,000	)
Payments		(871,000	)		(4,719,000	)		(2,343,000	)		(5,190,000	)		(1,695,000	)
Transfers to ORE		(21,000	)		0			(48,000	)		0			0
Net Additions/Deletions		6,329,000			2,898,000			17,746,000			318,000			0
Ending Balance	$	7,026,000		$	2,680,000		$	17,160,000		$	17,439,000		$	505,000
	Retail			Retail
	Home Equity			1-4 Family
	and Other			Mortgages
Retail Loan Portfolio:
Beginning Balance	$	0		$	1,987,000
Charge-Offs		0			0
Payments		0			(224,000	)
Transfers to ORE		0			0
Net Additions/Deletions		0			204,000
Ending Balance	$	0		$	1,967,000
Activity for acquired loans categorized as troubled debt restructurings during the last seven months of 2014 is as follows:
				Commercial
				Vacant Land,			Commercial			Commercial			Commercial
				Land									Real Estate -
	Commercial			Development,			Real Estate -			Real Estate -			Multi-Family
	and			and Residential			Owner			Non-Owner			and Residential
	Industrial			Construction			Occupied			Occupied			Rental
Commercial Loan Portfolio:
Beginning Balance	$	0		$	0		$	0		$	0		$	0
Charge-Offs		0			0			0			0			0
Payments		(2,000	)		0			0			0			(18,000	)
Transfers to ORE		0			0			0			0			0
Net Additions/Deletions		1,441,000			0			1,569,000			64,000			399,000
Ending Balance	$	1,439,000		$	0		$	1,569,000		$	64,000		$	381,000
	Retail			Retail
	Home Equity			1-4 Family
	and Other			Mortgages
Retail Loan Portfolio:
Beginning Balance	$	0		$	0
Charge-Offs		0			0
Payments		0			0
Transfers to ORE		0			0
Net Additions/Deletions		26,000			178,000
Ending Balance	$	26,000		$	178,000
Activity for loans categorized as troubled debt restructurings during 2013 is as follows:
				Commercial
				Vacant Land,			Commercial			Commercial			Commercial
				Land									Real Estate -
	Commercial			Development,			Real Estate -			Real Estate -			Multi-Family
	and			and Residential			Owner			Non-Owner			and Residential
	Industrial			Construction			Occupied			Occupied			Rental
Commercial Loan Portfolio:
Beginning Balance	$	2,720,000		$	3,071,000		$	4,116,000		$	37,671,000		$	3,027,000
Charge-Offs		(35,000	)		(725,000	)		(70,000	)		(2,537,000	)		(15,000	)
Payments		(2,781,000	)		(1,596,000	)		(2,151,000	)		(13,795,000	)		(735,000	)
Transfers to ORE		(74,000	)		0			(363,000	)		(1,153,000	)		0
Net Additions/Deletions		1,826,000			3,751,000			284,000			2,126,000			343,000
Ending Balance	$	1,656,000		$	4,501,000		$	1,816,000		$	22,312,000		$	2,620,000
	Retail			Retail
	Home Equity			1-4 Family
	and Other			Mortgages
Retail Loan Portfolio:
Beginning Balance	$	0		$	155,000
Charge-Offs		0			0
Payments		0			(46,000	)
Transfers to ORE		0			0
Net Additions/Deletions		0			1,878,000
Ending Balance	$	0		$	1,987,000
Activity for loans categorized as troubled debt restructurings during 2012 is as follows:
				Commercial
				Vacant Land,			Commercial			Commercial			Commercial
				Land									Real Estate -
	Commercial			Development,			Real Estate -			Real Estate -			Multi-Family
	and			and Residential			Owner			Non-Owner			and Residential
	Industrial			Construction			Occupied			Occupied			Rental
Commercial Loan Portfolio:
Beginning Balance	$	4,553,000		$	5,100,000		$	6,183,000		$	12,036,000		$	12,626,000
Charge-Offs		(540,000	)		(63,000	)		(426,000	)		(720,000	)		(2,180,000	)
Payments		(2,584,000	)		(2,013,000	)		(3,443,000	)		(2,482,000	)		(7,422,000	)
Transfers to ORE		(96,000	)		0			(65,000	)		(1,045,000	)		(186,000	)
Net Additions/Deletions		1,387,000			47,000			1,867,000			29,882,000			189,000
Ending Balance	$	2,720,000		$	3,071,000		$	4,116,000		$	37,671,000		$	3,027,000
	Retail			Retail
	Home Equity			1-4 Family
	and Other			Mortgages
Retail Loan Portfolio:
Beginning Balance	$	0		$	164,000
Charge-Offs		0			0
Payments		0			(9,000	)
Transfers to ORE		0			0
Net Additions/Deletions		0			0
Ending Balance	$	0		$	155,000
The allowance related to loans categorized as troubled debt restructurings was as follows:
	December 31,			December 31,
	2014			2013
Commercial:
Commercial and industrial	$	16,000		$	187,000
Vacant land, land development, and residential construction		151,000			798,000
Real estate – owner occupied		182,000			528,000
Real estate – non-owner occupied		4,778,000			7,828,000
Real estate – multi-family and residential rental		666,000			1,010,000
Total commercial		5,793,000			10,351,000
Retail:
Home equity and other		0			0
1-4 family mortgages		0			48,000
Total retail		0			48,000
Total related allowance	$	5,793,000		$	10,399,000
In general, our policy dictates that a renewal or modification of an 8- or 9-rated commercial loan meets the criteria of a troubled debt restructuring, although we review and consider all renewed and modified loans as part of our troubled debt restructuring assessment procedures. Loan relationships rated 8 contain significant financial weaknesses, resulting in a distinct possibility of loss, while relationships rated 9 reflect vital financial weaknesses, resulting in a highly questionable ability on our part to collect principal; we believe borrowers warranting such ratings would have difficulty obtaining financing from other market participants. Thus, due to the lack of comparable market rates for loans with similar risk characteristics, we believe 8- or 9-rated loans renewed or modified were done so at below market rates. Loans that are identified as troubled debt restructurings are considered impaired and are individually evaluated for impairment when assessing these credits in our allowance for loan losses calculation.

Note_5_Premises_and_Equipment_

Note 5 - Premises and Equipment, Net	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	NOTE 5 - PREMISES AND EQUIPMENT, NET
	Year-end premises and equipment were as follows:
		2014		2013
	Land and improvements	$	16,579,000	$	8,556,000
	Buildings		38,761,000		24,733,000
	Furniture and equipment		16,622,000		12,718,000
			71,962,000		46,007,000
	Less: accumulated depreciation		23,150,000		21,109,000
	Total premises and equipment	$	48,812,000	$	24,898,000
	Future lease payments total $1.8 million, comprised of $0.4 million in one year, $0.8 million in one to three years, $0.5 million in three to five years and $0.1 million in over five years. Depreciation expense totaled $2.3 million in 2014, $1.3 million in 2013, and $1.5 million in 2012.

Note_6_Mortgage_Loan_Servicing

Note 6 - Mortgage Loan Servicing	12 Months Ended
	Dec. 31, 2014
Mortgage Loan Servicing [Abstract]
Mortgage Loan Servicing [Text Block]	NOTE 6 – MORTGAGE LOAN SERVICING
	Mortgage loans serviced for others are not reported as assets in the Consolidated Balance Sheets. The mortgage loan servicing portfolio was acquired in the merger with Firstbank. The year-end aggregate unpaid principal balances of mortgage loans serviced for others were as follows:
		2014
	Mortgage loan portfolios serviced for:
	Federal Home Loan Mortgage Corporation	$	589,118,000
	Federal Home Loan Bank		1,702,000
	Total mortgage loans serviced for others	$	590,820,000
	Custodial escrow balances maintained in connection with serviced loans were $2.8 million as of December 31, 2014.
	Activity for capitalized mortgage loan servicing rights, included in other assets in the Consolidated Balance Sheets, during 2014 was as follows:
		2014
	Balance at January 1, 2014	$	0
	Firstbank merger		7,389,000
	Additions		575,000
	Amortized to expense		(1,252,000	)
	Balance at December 31, 2014	$	6,712,000
	We determined that no valuation allowance was necessary as of December 31, 2014. The estimated fair value of mortgage servicing rights was $7.3 million as of December 31, 2014. The fair value of mortgage servicing rights is estimated using a valuation model that calculates the present value of estimated future net servicing cash flows, taking into consideration expected mortgage loan prepayment rates, discount rates, servicing costs and other economic factors, which are determined based on current market conditions. Fair value was determined using a discount rate of 7.05%, a weighted average constant prepayment rate of 12.6%, depending on the stratification of the specific right, and a weighted average delinquency rate of 1.01%.
	The weighted average amortization period is 3.7 years as of December 31, 2014. Estimated amortization is as follows:
	2015	$	1,560,000
	2016		1,256,000
	2017		1,023,000
	2018		857,000
	2019		722,000
	Thereafter		1,294,000

Note_7_Core_Deposit_Intangible

Note 7 - Core Deposit Intangible Assets, Net	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Intangible Assets Disclosure [Text Block]	NOTE 7 – CORE DEPOSIT INTANGIBLE ASSETS, NET
	The gross carrying amount of core deposit intangible assets totaled $17.5 million as of December 31, 2014 (none at December 31, 2013). The accumulated amortization on core deposit intangible assets was $1.9 million, providing for a net carry balance of $15.6 million as of December 31, 2014.
	The estimated amortization expense on core deposit intangible assets in future periods is:
	2015	$	2,992,000
	2016		2,675,000
	2017		2,357,000
	2018		2,039,000
	2019		1,721,000
	Thereafter		3,839,000

Note_8_Deposits

Note 8 - Deposits	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Deposit Liabilities Disclosures [Text Block]	NOTE 8 – DEPOSITS
	Deposits at year-end are summarized as follows:
												Percent
		31-Dec-14					31-Dec-13					Increase
		Balance		%			Balance		%			(Decrease)
	Noninterest-bearing demand	$	558,738,000		24.5	%	$	224,580,000		20.1	%		148.8	%
	Interest-bearing checking		413,382,000		18.2			197,388,000		17.6			109.4
	Money market		235,587,000		10.3			133,369,000		11.9			76.6
	Savings		330,459,000		14.5			52,606,000		4.7			528.2
	Time, under $100,000		181,026,000		8			43,251,000		3.9			318.5
	Time, $100,000 and over		382,120,000		16.8			254,600,000		22.8			50.1
			2,101,312,000		92.3			905,794,000		81			132
	Out-of-area time, under $100,000		2,422,000		0.1			4,078,000		0.4			(40.6	)
	Out-of-area time, $100,000 and over		173,181,000		7.6			209,039,000		18.6			(17.2	)
			175,603,000		7.7			213,117,000		19			(17.6	)
	Total deposits	$	2,276,915,000		100	%	$	1,118,911,000		100	%		103.5
	Out-of-area certificates of deposit consist of certificates obtained from depositors outside of our primary market areas almost exclusively through deposit brokers.
	The following table depicts the maturity distribution for certificates of deposit at year-end:
		2014		2013
	In one year or less	$	368,163,000	$	213,454,000
	In one to two years		153,346,000		80,138,000
	In two to three years		118,919,000		73,271,000
	In three to four years		60,953,000		95,979,000
	In four to five years		37,368,000		48,126,000
	Total certificates of deposit	$	738,749,000	$	510,968,000
	The following table depicts the maturity distribution for certificates of deposit with balances of $100,000 or more at year-end:
		2014		2013
	Up to three months	$	75,356,000	$	57,469,000
	Three months to six months		65,838,000		41,237,000
	Six months to twelve months		125,492,000		93,920,000
	Over twelve months		288,615,000		271,013,000
	Total certificates of deposit	$	555,301,000	$	463,639,000

Note_9_Securities_Sold_Under_A

Note 9 - Securities Sold Under Agreements to Repurchase	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Repurchase Agreements, Resale Agreements, Securities Borrowed, and Securities Loaned Disclosure [Text Block]	NOTE 9 – SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE
	Information regarding securities sold under agreements to repurchase at year-end is summarized below:
		2014			2013
	Outstanding balance at year-end	$	167,569,000		$	69,305,000
	Weighted average interest rate at year-end		0.11	%		0.12	%
	Average daily balance during the year	$	105,474,000		$	65,939,000
	Weighted average interest rate during the year		0.12	%		0.12	%
	Maximum daily balance during the year	$	178,042,000		$	78,960,000
	Securities sold under agreements to repurchase (“repurchase agreements”) generally have original maturities of less than one year. Repurchase agreements are treated as financings, and the obligations to repurchase securities sold are reflected as liabilities. Securities involved with the repurchase agreements are recorded as assets of our Bank and are held in safekeeping by a correspondent bank. Repurchase agreements are offered principally to certain large deposit customers. Repurchase agreements are secured by securities with an aggregate fair value equal to the aggregate outstanding balance.

Note_10_Federal_Home_Loan_Bank

Note 10 - Federal Home Loan Bank Advances	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Federal Home Loan Bank Advances, Disclosure [Text Block]	NOTE 10 - FEDERAL HOME LOAN BANK ADVANCES
	Federal Home Loan Bank (“FHLB”) advances totaled $54.0 million at December 31, 2014, and mature at varying dates from January 2015 through September 2017, with fixed rates of interest from 0.62% to 1.51% and averaging 1.26%. FHLB advances totaled $45.0 million at December 31, 2013, and were expected to mature at varying dates ranging from March 2017 through September 2017, with fixed rates of interest from 1.22% to 1.51% and averaging 1.34%.
	Each advance is payable at its maturity date, and is subject to a prepayment fee if paid prior to the maturity date. The advances are generally collateralized by a blanket lien on our residential mortgage loan portfolio. Our borrowing line of credit as of December 31, 2014 totaled $409.5 million, with availability of $355.5 million.
	Maturities over the next five years are:
	2015	$	6,022,000
	2016		3,000,000
	2017		45,000,000
	2018		0
	2019		0

Note_11_Federal_Income_Taxes

Note 11 - Federal Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	NOTE 11 - FEDERAL INCOME TAXES
	The consolidated income tax expense is as follows:
		2014			2013			2012
	Current expense	$	3,359,000		$	0		$	0
	Deferred expense		4,506,000			8,092,000			5,636,000
	Tax expense	$	7,865,000		$	8,092,000		$	5,636,000
	A reconciliation of the differences between the federal income tax expense recorded and the amount computed by applying the federal statutory rate to income before income taxes is as follows:
		2014			2013			2012
	Tax at statutory rate (35%)	$	8,819,000		$	8,794,000		$	6,360,000
	Increase (decrease) from
	Tax-exempt interest		(621,000	)		(347,000	)		(486,000	)
	Bank owned life insurance		(415,000	)		(465,000	)		(535,000	)
	Other		82,000			110,000			297,000
	Tax expense	$	7,865,000		$	8,092,000		$	5,636,000
	Significant components of deferred tax assets and liabilities as of December 31, 2014 and 2013 are as follows:
		2014			2013
	Deferred income tax assets
	Allowance for loan losses	$	7,014,000		$	7,987,000
	Tax credit carryforwards		3,395,000			1,397,000
	Nonaccrual loan interest income		471,000			605,000
	Deferred compensation		1,304,000			567,000
	Deferred loan fees		445,000			273,000
	Fair value write-downs on foreclosed properties		212,000			241,000
	Fair value of interest rate swap		89,000			92,000
	Losses on capital investments		450,000			0
	Stock compensation		521,000			207,000
	Net operating loss carryforward		0			4,050,000
	Unrealized loss on securities		0			2,908,000
	Other		725,000			136,000
			14,626,000			18,463,000
	Deferred income tax liabilities
	Depreciation		1,217,000			419,000
	Prepaid expenses		425,000			192,000
	Core deposit intangible		5,386,000			0
	Mortgage loan servicing rights		2,349,000			0
	Unrealized gain on securities		112,000			0
	Other		476,000			98,000
			9,965,000			709,000
	Net deferred tax asset before valuation allowance		4,661,000			17,754,000
	Valuation allowance		(450,000	)		0
	Total net deferred tax asset	$	4,211,000		$	17,754,000
	A valuation allowance related to deferred tax assets is required when it is considered more likely than not that all or part of the benefits related to such assets will not be realized. We do not believe the deferred tax asset related to losses on certain capital investments acquired in our merger with Firstbank is more likely than not to be realized. Therefore, we established a valuation allowance of $0.5 million in connection with the acquisition accounting at the time of the merger.
	At December 31, 2014, we had carryforwards of the following tax attributes: general business tax credits of $0.6 million that expire in the years 2028 through 2034; and $2.8 million of federal alternative minimum tax credits with an indefinite life.
	We had no unrecognized tax benefits at any time during 2014 or 2013 and do not anticipate any significant increase in unrecognized tax benefits during 2015. Should the accrual of any interest or penalties relative to unrecognized tax benefits be necessary, it is our policy to record such accruals in our income tax accounts; no such accruals existed at any time during 2014 or 2013. Our U.S. federal income tax returns are no longer subject to examination for all years before 2011.

Note_12_Stockbased_Compensatio

Note 12 - Stock-based Compensation	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	NOTE 12 – STOCK-BASED COMPENSATION
	Stock-based compensation plans are used to provide directors and employees with an increased incentive to contribute to our long-term performance and growth, to align the interests of directors and employees with the interests of our shareholders through the opportunity for increased stock ownership and to attract and retain directors and employees. From 2000 through 2005, stock option grants were provided to directors and certain employees through several stock option plans, including the 2000 Employee Stock Option Plan, 2004 Employee Stock Option Plan and Independent Director Stock Option Plan. During 2006, 2007 and 2008, stock option and restricted stock grants were provided to certain employees through the Stock Incentive Plan of 2006. No stock option or restricted stock grants were made during 2009, 2010 or 2011. During 2012, restricted stock grants were provided to directors and certain employees through the Stock Incentive Plan of 2006. No stock option or restricted stock grants were made during 2013 due to the pending merger with Firstbank. During 2014, stock option and restricted stock grants were provided to certain employees through the Stock Incentive Plan of 2006. In addition, stock grants were provided to directors as retainer payments during 2014 through the Stock Incentive Plan of 2006.
	Under our 2000 Employee Stock Option Plan and 2004 Employee Stock Option Plan, stock options granted to employees were granted at the market price on the date of grant, generally fully vested after one year and expired ten years from the date of grant. Stock options granted to non-executive officers during 2005 vested about three weeks after being granted. Under our Independent Director Stock Option Plan, stock options granted to non-employee directors were at 125% of the market price on the date of grant, fully vested after five years and expire ten years from the date of grant.
	The Stock Incentive Plan of 2006 replaced all of our outstanding stock option plans for stock options not previously granted. Under the Stock Incentive Plan of 2006, incentive awards may include, but are not limited to, stock options, restricted stock, stock appreciation rights and stock awards. Incentive awards that are stock options or stock appreciation rights are granted with an exercise price not less than the closing price of our common stock on the date of grant, or for stock options granted in 2006 or 2007, the day before the date of grant, if the closing price was higher on the day before the date of grant. Price, vesting and expiration date parameters are determined by Mercantile’s Compensation Committee on a grant-by-grant basis. Generally, the stock options granted to employees during 2006, 2007 and 2008 fully vested after two years and expire after seven years. The restricted stock awards granted to certain employees during 2006, 2007 and 2008 fully vested after four years, while the restricted stock awards granted to directors and certain employees during 2012 fully vested after two years. No payments were required from employees for the restricted stock awards. The restricted stock awards granted to certain employees during 2014 fully vest after three years. The stock options granted to certain employees during 2014, which were at 110% of the market price on the date of grant, fully vest after two years and expire after seven years. At year-end 2014, there were approximately 277,000 shares authorized for future incentive awards.
	In conjunction with the Firstbank merger, all of our outstanding restricted stock awards, which were scheduled to vest in full in November, 2014, became fully vested on June 1, 2014, resulting in the recognition of compensation expense of $0.2 million in the second quarter of 2014 to reflect the accelerated vesting of the restricted stock awards. The unrecognized compensation cost related to unvested stock options was less than $0.1 million as of December 31, 2014, which will be recognized as expense over the next two years. The unrecognized compensation cost related to restricted stock grants was $2.0 million as of December 31, 2014, which will be recognized as expense over the next three years.
	Also in conjunction with the Firstbank merger, we issued Mercantile stock options in replacement of all outstanding Firstbank stock option grants that had been previously issued to Firstbank employees under the Firstbank Corporation Stock Option and Restricted Stock Plan of 1997 and the Firstbank Corporation 2006 Stock Compensation Plan. In general, stock option grants for 50 shares or less fully vested after one year from date of grant, while stock option grants for more than 50 shares vested over a five-year period at 20% of the grant per annum starting one year from date of grant. The stock option grants expire ten years from date of grant. There were approximately 282,200 Mercantile stock options issued as a result of the merger, with about 258,400 of the stock option grants fully vested and exercisable on the date of merger. Unrecognized compensation cost related to the unvested stock options was less than $0.1 million as of December 31, 2014, which will be fully expensed during 2015.
	A summary of restricted stock activity from grants issued under the Mercantile Stock Incentive Plan of 2006 during the past three years is as follows:
			2014							2013					2012
							Weighted						Weighted					Weighted
							Average						Average					Average
			Shares				Fair Value			Shares			Fair Value		Shares			Fair Value
	Nonvested at beginning of year			63,800			$	14.3			66,100		$	14.3		38,650		$	6.2
	Granted			101,490				20.13			0		NA			66,100			14.3
	Vested			(63,300	)			14.3			0		NA			(38,266	)		6.2
	Forfeited			(500	)			14.3			(2,300	)		14.3		(384	)		6.2
	Nonvested at end of year			101,490			$	20.13			63,800		$	14.3		66,100		$	14.3
	A summary of stock option activity from grants issued under various Mercantile plans during the past three years is as follows:
			2014							2013					2012
							Weighted						Weighted					Weighted
							Average						Average					Average
							Exercise						Exercise					Exercise
			Shares				Price			Shares			Price		Shares			Price
	Outstanding at beginning of year			60,876			$	33.11			152,896		$	26.15		214,903		$	22.4
	Granted			6,488				22.15			0		NA			0		NA
	Exercised			(2,845	)			17.74			(51,055	)		13.72		(50,930	)		10.83
	Forfeited or expired			(29,184	)			34.6			(40,965	)		31.3		(11,077	)		23.77
	Outstanding at end of year			35,335			$	31.09			60,876		$	33.11		152,896		$	26.15
	Options exercisable at year-end			28,847			$	33.11			60,876		$	33.11		152,896		$	26.15
	The fair value of each stock option award is estimated on the date of grant using a closed option valuation (Black-Scholes) model that uses the assumptions noted in the table below. Expected volatilities are based on historical volatilities on our common stock. Historical data is used to estimate stock option expense and post-vesting termination behavior. The expected term of stock options granted is based on historical data and represents the period of time that stock options granted are expected to be outstanding, which takes into account that the stock options are not transferable. The risk-free interest rate for the expected term of the stock option is based on the U.S. Treasury yield curve in effect at the time of the stock option grant.
	The fair value of stock options granted during 2014 was determined using the following weighted-average assumptions as of the grant date. No stock options were granted during 2013 or 2012.
			2014
	Risk-free interest rate			1.56	%
	Expected option life (Years)			5
	Expected stock price volatility			26	%
	Dividend yield			2.5	%
	Options issued under various Mercantile plans outstanding at year-end 2014 were as follows:
						Outstanding							Exercisable
									Weighted Average	Weighted					Weighted
	Range of								Remaining	Average					Average
	Exercise								Contractual	Exercise					Exercise
	Prices					Number			Life (Years)	Price			Number		Price
	$6.21	-	$8.00				2,700		0.9	$	6.21			2,700	$	6.21
	$20.01	-	$24.00				6,488		6.9		22.15			0	NA
	$32.01	-	$36.00				26,147		0.9		35.88			26,147		35.88
	Outstanding at year end						35,335		2	$	31.09			28,847	$	33.11
	Information related to options issued under various Mercantile plans outstanding at year-end 2014, 2013 and 2012 is as follows:
			2014				2013			2012
	Minimum exercise price		$	6.21			$	6.21		$	6.21
	Maximum exercise price			35.88				40.28			40.28
	Average remaining option term (Years)		2				1.4			1.9
	Information related to stock option grants and exercises issued under various Mercantile plans during 2014, 2013 and 2012 is as follows:
			2014				2013			2012
	Aggregate intrinsic value of stock options exercised		$	11,000			$	408,000		$	307,000
	Cash received from stock option exercises			50,000				289,000			227,000
	Tax benefit realized from stock option exercises			0				0			0
	Weighted average per share fair value of stock options granted		$	2.72				NA			NA
	The aggregate intrinsic value of all stock options issued under various Mercantile plans outstanding and exercisable at December 31, 2014 was less than $0.1 million. Shares issued as a result of the exercise of stock option grants have been authorized and previously unissued shares.
	A summary of stock option activity from grants issued under various Firstbank plans that became part of Mercantile’s plans upon consummation of the merger on June 1, 2014 is as follows:
			2014
							Weighted
							Average
							Exercise
			Shares				Price
	Outstanding at beginning of year			0				0
Granted			0				0
Replaced as part of merger			282,178				15.48
Exercised			(27,740	)			8.34
Forfeited or expired			(36,456	)			24.46
Outstanding at end of year			217,982			$	14.89
Options exercisable at year-end			210,777			$	15.22
Options issued under various Firstbank plans outstanding at year-end 2014 were as follows:
					Outstanding							Exercisable
								Weighted Average	Weighted					Weighted
Range of								Remaining	Average					Average
Exercise								Contractual	Exercise					Exercise
Prices					Number			Life (Years)	Price			Number		Price
$4.00	-	$8.00				63,590		4.9	$	6.53			56,385	$	6.7
$8.01	-	$12.00				68,430		3.7		13.2			68,430		13.2
$20.01	-	$25.00				85,962		1.4		22.43			85,962		22.43
Outstanding at year end						217,982		3.1	$	14.89			210,777	$	15.22
Information related to options issued under various Firstbank plans outstanding at year-end 2014 is as follows:
		2014
Minimum exercise price		$	5.19
Maximum exercise price			24.46
Average remaining option term (Years)		3.1
Information related to stock option grants and exercises issued under various Firstbank plans during 2014 is as follows:
		2014
Aggregate intrinsic value of stock options exercised		$	333,000
Cash received from stock option exercises			232,000
Tax benefit realized from stock option exercises			116,000
Weighted average per share fair value of stock options granted		NA
The aggregate intrinsic value of all stock options issued under various Firstbank plans outstanding and exercisable at December 31, 2014 was $1.3 million. Shares issued as a result of the exercise of stock option grants have been authorized and previously unissued shares.
On June 26, 2014, we granted a total of 7,375 shares of common stock to our Corporate, Bank and Regional Advisory Boards of Directors for retainer payments for the period of June 1, 2014 through December 31, 2014. The associated $0.2 million cost was expensed on a straightline basis over the last six months of 2014.

Note_13_Related_Parties

Note 13 - Related Parties	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	NOTE 13 – RELATED PARTIES
	Certain directors and executive officers of the Bank, including their immediate families and companies in which they are principal owners, were loan customers of the Bank. At year-end 2014 and 2013, the Bank had $15.8 million and $7.8 million in loan commitments to directors and executive officers, of which $9.0 million and $6.9 million were outstanding at year-end 2014 and 2013, respectively, as reflected in the following table. The line item entitled “Adjustments” primarily relates to the Firstbank merger in 2014 and Board member retirements during 2013.
		2014			2013
	Beginning balance	$	6,884,000		$	1,418,000
	New loans		781,000			6,309,000
	Repayments		(381,000	)		(252,000	)
	Adjustments		1,718,000			(591,000	)
	Ending balance	$	9,002,000		$	6,884,000
	Related party deposits and repurchase agreements totaled $16.6 million and $3.9 million at year-end 2014 and 2013, respectively.

Note_14_Commitments_and_Offbal

Note 14 - Commitments and Off-balance-sheet Risk	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block Supplement [Abstract]
Commitments Contingencies and Guarantees [Text Block]	NOTE 14 – COMMITMENTS AND OFF-BALANCE-SHEET RISK
	We are a party to financial instruments with off-balance sheet risk in the normal course of business to meet the financing needs of our customers. These financial instruments include commitments to extend credit and standby letters of credit. Loan commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Standby letters of credit are conditional commitments issued by our Bank to guarantee the performance of a customer to a third party. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements.
	These instruments involve, to varying degrees, elements of credit risk in excess of the amount recognized, if any, in the balance sheet. Our maximum exposure to loan loss in the event of nonperformance by the other party to the financial instrument for commitments to extend credit and standby letters of credit is represented by the contractual notional amount of those instruments. We use the same credit policies in making commitments and conditional obligations as we do for on-balance sheet instruments. Collateral, such as accounts receivable, securities, inventory, and property and equipment, is generally obtained based on management’s credit assessment of the borrower. If required, estimated loss exposure resulting from these instruments is expensed and recorded as a liability. There was no liability balance for these instruments as of December 31, 2014 and 2013.
	At year-end 2014 and 2013, the rates on existing off-balance sheet instruments were substantially equivalent to current market rates, considering the underlying credit standing of the counterparties.
	Our maximum exposure to credit losses for loan commitments and standby letters of credit outstanding at year-end was as follows:
		2014		2013
	Commercial unused lines of credit	$	554,856,000	$	257,937,000
	Unused lines of credit secured by 1 – 4 family residential properties		60,983,000		23,429,000
	Credit card unused lines of credit		11,649,000		9,013,000
	Other consumer unused lines of credit		8,673,000		5,695,000
	Commitments to make loans		110,126,000		58,799,000
	Standby letters of credit		35,461,000		19,670,000
	Total commitments	$	781,748,000	$	374,543,000
	Commitments to make loans generally reflect our binding obligations to existing and prospective customers to extend credit, including line of credit facilities secured by accounts receivable and inventory, and term debt secured by either real estate or equipment. In most instances, line of credit facilities are for a one-year term and are at a floating rate tied to the Mercantile Bank Prime Rate, the Wall Street Journal Prime Rate or the 30-Day Libor rate. For term debt secured by real estate, customers are generally offered a floating rate tied to the Mercantile Bank Prime Rate or Wall Street Journal Prime Rate, and a fixed rate currently ranging from 4.00% to 7.00%. These credit facilities generally balloon within five years, with payments based on amortizations ranging from 10 to 20 years. For term debt secured by non-real estate collateral, customers are generally offered a floating rate tied to the Mercantile Bank Prime Rate or Wall Street Journal Prime Rate, and a fixed rate currently ranging from 4.00% to 7.50%. These credit facilities generally mature and fully amortize within five years.
	Certain of our commercial loan customers have entered into interest rate swap agreements directly with our correspondent banks. To assist our commercial loan customers in these transactions, and to encourage our correspondent banks to enter into the interest rate swap transactions with minimal credit underwriting analyses on their part, we have entered into risk participation agreements with the correspondent banks whereby we agree to make payments to the correspondent banks owed by our commercial loan customers under the interest rate swap agreement in the event that our commercial loan customers do not make the payments. We are not a party to the interest rate swap agreements under these arrangements. As of December 31, 2014, the total notional amount of the underlying interest rate swap agreements was $15.4 million, with a net fair value from our commercial loan customers’ perspective of negative $2.9 million. These risk participation agreements are considered financial guarantees in accordance with applicable accounting guidance and are therefore recorded as liabilities at fair value, generally equal to the fees collected at the time of their execution. These liabilities are accreted into income during the terms of the interest rate swap agreements, generally ranging from an original term of four to fifteen years, and totaled less than $0.1 million at December 31, 2014 and December 31, 2013.
	The following instruments are considered financial guarantees under current accounting guidance. These instruments are carried at fair value.
		2014				2013
		Contract		Carrying		Contract		Carrying
		Amount		Value		Amount		Value
	Standby letters of credit	$	35,461,000	$	150,000	$	19,670,000	$	148,000
	We were required to have $8.4 million and $1.5 million of cash on hand or on deposit with the Federal Reserve Bank of Chicago to meet regulatory reserve and clearing requirements at year-end 2014 and 2013, respectively.

Note_15_Benefit_Plans

Note 15 - Benefit Plans	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Pension and Other Postretirement Benefits Disclosure [Text Block]	NOTE 15 – BENEFIT PLANS
	We have a 401(k) benefit plan that covers substantially all of our employees. The percent of our matching contributions to the 401(k) benefit plan is determined annually by the Board of Directors. The matching contribution was 3% as of January 1, 2012, and then increased to 4% as of October 1, 2012. Effective January 1, 2014, the matching contribution was increased to 4.25%. Matching contributions, if made, are immediately vested. Our 2014, 2013 and 2012 matching 401(k) contributions charged to expense were $0.9 million, $0.5 million and $0.4 million, respectively.
	We have a deferred compensation plan in which all persons serving on the Board of Directors may defer all or portions of their annual retainer and meeting fees, with distributions to be paid upon termination of service as a director or specific dates selected by the director. We also have a non-qualified deferred compensation program in which selected officers may defer all or portions of salary and bonus payments. The deferred amounts, totaling $3.7 million and $1.6 million as of December 31, 2014 and 2013, respectively, are categorized as other liabilities in the Consolidated Balance Sheets, and are paid interest at a rate equal to the Wall Street Journal Prime Rate. Interest expense is insignificant for all periods presented.
	The Mercantile Bank Corporation Employee Stock Purchase Plan of 2002 was replaced by the Mercantile Bank Corporation Employee Stock Purchase Plan of 2014 (herein after referred to as the “Stock Purchase Plans”) in June of 2014. The Stock Purchase Plans are non-compensatory plans intended to encourage full- and part-time employees of Mercantile and its subsidiaries to promote our best interests and to align employees’ interests with the interests of our shareholders by permitting employees to purchase shares of our common stock through regular payroll deductions. Shares are purchased on the last business day of each calendar quarter at a price equal to the consolidated closing bid price of our common stock reported on The Nasdaq Stock Market. A total of 250,000 shares of common stock may be issued under the existing plan; however, the number of shares may be adjusted to reflect any stock dividends and other changes in our capitalization. The number of shares issued under the Stock Purchase Plans totaled 1,150 and 1,098 in 2014 and 2013, respectively. As of December 31, 2014, there were 28,850 shares available under our current plan.

Note_16_Hedging_Activities

Note 16 - Hedging Activities	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	NOTE 16 – HEDGING ACTIVITIES
	Our interest rate risk policy includes guidelines for measuring and monitoring interest rate risk. Within these guidelines, parameters have been established for maximum fluctuations in net interest income. Possible fluctuations are measured and monitored using net interest income simulation. Our policy provides for the use of certain derivative instruments and hedging activities to aid in managing interest rate risk to within policy parameters.
	In February 2012, we entered into an interest rate swap agreement with a correspondent bank to hedge the floating rate on the subordinated debentures issued to Mercantile Bank Capital Trust I, which became effective in January 2013 and matures in January 2018. The $32.0 million of subordinated debentures have a rate equal to the 90-Day Libor Rate plus a fixed spread of 218 basis points, and are subject to repricing quarterly. The interest rate swap agreement provides for us to pay our correspondent bank a fixed rate, while our correspondent bank will pay us the 90-Day Libor Rate on a $32.0 million notional amount. The quarterly re-set dates for the floating rate on the interest rate swap agreement are the same as the re-set dates for the floating rate on the subordinated debentures. The interest rate swap agreement qualifies for hedge accounting; therefore, fluctuations in the fair value of the interest rate swap agreement, net of tax effect, are recorded in other comprehensive income. As of December 31, 2014 and 2013, the fair value of the interest rate swap agreement was recorded as a liability in the amount of $0.3 million.

Note_17_Fair_Values_of_Financi

Note 17 - Fair Values of Financial Instruments	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	NOTE 17 – FAIR VALUES OF FINANCIAL INSTRUMENTS
	Carrying amount, estimated fair value and level within the fair value hierarchy of financial instruments were as follows at year-end (dollars in thousands):
			Level in		2014				2013
			Fair Value		Carrying		Fair		Carrying		Fair
			Hierarchy		Amount		Value		Amount		Value
	Financial assets
	Cash		Level 1		$	13,261	$	13,261	$	1,464	$	1,464
	Cash equivalents		Level 2			159,477		159,477		145,501		145,501
	Securities available for sale			-1		432,912		432,912		131,178		131,178
	Federal Home Loan Bank stock			-2		13,699		13,699		11,961		11,961
	Loans, net		Level 3			2,069,236		2,064,140		1,030,422		1,027,300
	Bank owned life insurance		Level 2			57,861		57,861		51,377		51,377
	Accrued interest receivable		Level 2			8,033		8,033		3,649		3,649
	Financial liabilities
	Deposits		Level 2			2,276,915		2,254,749		1,118,911		1,120,576
	Securities sold under agreements to repurchase		Level 2			167,569		167,569		69,305		69,305
	Federal Home Loan Bank advances		Level 2			54,022		54,720		45,000		45,139
	Subordinated debentures		Level 2			54,472		54,508		32,990		32,974
	Accrued interest payable		Level 2			1,942		1,942		2,041		2,041
	Interest rate swap			-1		253		253		264		264
	-1	See Note 18 for a description of the fair value hierarchy as well as a disclosure of levels for classes of financial assets and liabilities.
	-2	It is not practical to determine the fair value of FHLB stock due to transferability restrictions.
	Carrying amount is the estimated fair value for cash and cash equivalents, Federal Home Loan Bank stock, accrued interest receivable and payable, bank owned life insurance, demand deposits, securities sold under agreements to repurchase, and variable rate loans and deposits that reprice frequently and fully. Security fair values are based on market prices or dealer quotes, and if no such information is available, on the rate and term of the security and information about the issuer. For fixed rate loans and deposits and for variable rate loans and deposits with infrequent repricing or repricing limits, fair value is based on discounted cash flows using current market rates applied to the estimated life and credit risk. Fair value of subordinated debentures and Federal Home Loan Bank advances is based on current rates for similar financing. Fair value of the interest rate swap is determined primarily utilizing market-consensus forecasted yield curves. Fair value of off-balance sheet items is estimated to be nominal.

Note_18_Fair_Values_Measuremen

Note 18 - Fair Values Measurements	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Fair Value, Measurement Inputs, Disclosure [Text Block]	NOTE 18 – FAIR VALUE MEASUREMENTS
	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. A fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability, or in the absence of a principal market, the most advantageous market for the asset or liability. The price of the principal (or most advantageous) market used to measure the fair value of the asset or liability is not adjusted for transaction costs. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for marketing activities that are usual and customary for transactions involving such assets and liabilities; it is not a forced transaction. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact and (iv) willing to transact.
	We are required to use valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets and liabilities. The income approach uses valuation techniques to convert future amounts, such as cash flows or earnings, to a single present amount on a discounted basis. The cost approach is based on the amount that currently would be required to replace the service capacity of an asset (replacement cost). Valuation techniques should be consistently applied. Inputs to valuation techniques refer to the assumptions that market participants would use in pricing the asset or liability. Inputs may be observable, meaning those that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from independent sources, or unobservable, meaning those that reflect our own estimates about the assumptions market participants would use in pricing the asset or liability based on the best information available in the circumstances. In that regard, we utilize a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The fair value hierarchy is as follows:
	Level 1: Quoted prices (unadjusted) for identical assets or liabilities in active markets that we have the ability to access as of the measurement date.
	Level 2: Significant other observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities in markets that are not active; or other inputs that are observable or can be derived from or corroborated by observable market data by correlation or other means.
	Level 3: Significant unobservable inputs that reflect our own estimates about the assumptions that market participants would use in pricing an asset or liability.
	The following is a description of our valuation methodologies used to measure and disclose the fair values of our financial assets and liabilities on a recurring or nonrecurring basis:
	Securities available for sale. Securities available for sale are recorded at fair value on a recurring basis. Fair value measurement is based on quoted prices, if available. If quoted prices are not available, fair values are measured using independent pricing models. Level 2 securities include U.S. Government agency debt obligations, mortgage-backed securities issued or guaranteed by U.S. Government agencies, municipal general obligation and revenue bonds, and mutual funds. Level 3 securities include bonds issued by certain relatively small municipalities located within our markets that have very limited marketability due to their size and lack of ratings from a recognized rating service. We carry these bonds at historical cost, which we believe approximates fair value, unless our periodic financial analysis or other information becomes known which necessitates a valuation allowance. There was no such valuation allowance as of December 31, 2014 or 2013. We have no Level 1 securities available for sale.
	Mortgage loans held for sale. Mortgage loans held for sale are carried at the lower of aggregate cost or fair value and are measured on a nonrecurring basis. Fair value is based on independent quoted market prices, where applicable, or the prices for other mortgage whole loans with similar characteristics. As of December 31, 2014 and 2013, we determined that the fair value of our mortgage loans held for sale approximated the recorded cost of $1.6 million and $1.1 million, respectively.
	Loans. We do not record loans at fair value on a recurring basis. However, from time to time, we record nonrecurring fair value adjustments to collateral dependent loans to reflect partial write-downs or specific reserves that are based on the observable market price or current estimated value of the collateral. These loans are reported in the nonrecurring table below at initial recognition of impairment and on an ongoing basis until recovery or charge-off.
	Foreclosed assets. At time of foreclosure or repossession, foreclosed and repossessed assets are adjusted to fair value less costs to sell upon transfer of the loans to foreclosed and repossessed assets, establishing a new cost basis. We subsequently adjust estimated fair value on foreclosed assets on a nonrecurring basis to reflect write-downs based on revised fair value estimates.
	Derivatives. The interest rate swap agreement is measured at fair value on a recurring basis. We measure fair value utilizing models that use primarily market observable inputs, such as forecasted yield curves, and accordingly, the interest rate swap agreement is classified as Level 2.
	Assets and Liabilities Measured at Fair Value on a Recurring Basis
	The balances of assets and liabilities measured at fair value on a recurring basis as of December 31, 2014 are as follows:
					Quoted Prices
					in Active		Significant
					Markets for		Other			Significant
					Identical		Observable			Unobservable
					Assets		Inputs			Inputs
		Total			(Level 1)		(Level 2)			(Level 3)
	Available for sale securities
	U.S. Government agency debt obligations	$	193,468,000		$	0	$	193,468,000		$	0
	Mortgage-backed securities		93,561,000			0		93,561,000			0
	Municipal general obligation bonds		133,082,000			0		122,801,000			10,281,000
	Municipal revenue bonds		10,873,000			0		10,873,000			0
	Other investments		1,928,000			0		1,928,000			0
	Derivatives
	Interest rate swap agreement		(253,000	)		0		(253,000	)		0
	Total	$	432,659,000		$	0	$	422,378,000		$	10,281,000
	There were no transfers in or out of Level 1, Level 2 or Level 3 during 2014. The Level 3 investments in the table above originated from the merger with Firstbank.
	The balances of assets and liabilities measured at fair value on a recurring basis as of December 31, 2013 are as follows:
					Quoted Prices
					in Active		Significant
					Markets for		Other			Significant
					Identical		Observable			Unobservable
					Assets		Inputs			Inputs
		Total			(Level 1)		(Level 2)			(Level 3)
	Available for sale securities U.S. Government agency debt obligations	$	98,477,000		$	0	$	98,477,000		$	0
	Mortgage-backed securities		13,558,000			0		13,558,000			0
	Municipal general obligation bonds		16,872,000			0		16,872,000			0
	Municipal revenue bonds		916,000			0		916,000			0
	Mutual funds		1,355,000			0		1,355,000			0
	Derivatives
	Interest rate swap agreement		(264,000	)		0		(264,000	)		0
	Total	$	130,914,000		$	0	$	130,914,000		$	0
	There were no transfers in or out of Level 1, Level 2 or Level 3 during 2013.
	Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis
	The balances of assets and liabilities measured at fair value on a nonrecurring basis as of December 31, 2014 are as follows:
					Quoted Prices
					in Active		Significant
					Markets for		Other			Significant
					Identical		Observable			Unobservable
					Assets		Inputs			Inputs
		Total			(Level 1)		(Level 2)			(Level 3)
	Impaired loans (1)	$	17,097,000		$	0	$	0		$	17,097,000
	Foreclosed assets (1)		1,995,000			0		0			1,995,000
	Total	$	19,092,000		$	0	$	0		$	19,092,000
	The balances of assets and liabilities measured at fair value on a nonrecurring basis as of December 31, 2013 are as follows:
					Quoted Prices
					in Active		Significant
					Markets for		Other			Significant
					Identical		Observable			Unobservable
					Assets		Inputs			Inputs
		Total			(Level 1)		(Level 2)			(Level 3)
Impaired loans (1)	$	23,405,000		$	0	$	0		$	23,405,000
Foreclosed assets (1)		2,851,000			0		0			2,851,000
Total	$	26,256,000		$	0	$	0		$	26,256,000
(1) Represents carrying value and related write-downs for which adjustments are based on the estimated value of the property or other assets.
Fair value estimates of collateral on impaired loans, as well as on foreclosed assets, are reviewed periodically. Our credit policies establish criteria for obtaining appraisals and determining internal value estimates. We may also adjust outside appraisals and internal evaluations based on identifiable trends within our markets, such as sales of similar properties or assets, listing prices and offers received. In addition, we may discount certain appraised and internal value estimates to address current distressed market conditions.

Note_19_Earnings_Per_Share

Note 19 - Earnings Per Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	NOTE 19 – EARNINGS PER SHARE
	The factors used in the earnings per share computation follow:
		2014		2013		2012
	Basic
	Net income attributable to common shares	$	17,331,000	$	17,033,000	$	11,505,000
	Weighted average common shares outstanding		13,510,991		8,710,677		8,625,198
	Basic earnings per common share	$	1.28	$	1.96	$	1.33
	Diluted
	Net income attributable to common shares	$	17,331,000	$	17,033,000	$	11,505,000
	Weighted average common shares outstanding for basic earnings per common share		13,510,991		8,710,677		8,625,198
	Add: Dilutive effects of share-based awards		30,913		14,031		224,429
	Average shares and dilutive potential common shares		13,541,904		8,724,708		8,849,627
	Diluted earnings per common share	$	1.28	$	1.95	$	1.3
	Stock options for approximately 168,000, 55,000 and 132,000 shares of common stock were antidilutive and were not included in determining dilutive earnings per share in 2014, 2013, and 2012, respectively.

Note_20_Subordinated_Debenture

Note 20 - Subordinated Debentures	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Debt Disclosure [Text Block]	NOTE 20 – SUBORDINATED DEBENTURES
	We have five business trusts that are wholly-owned subsidiaries of Mercantile, four of which were assumed by Mercantile in conjunction with the Firstbank merger. A fair value discount of $15.0 million was recorded at the time of the merger, which is being amortized at $0.7 million annually over the next 21.5 years. Each of the trusts was formed to issue Preferred Securities that were sold in private sales, as well as selling Common Securities to Mercantile. The proceeds from the Preferred and Common Securities sales were used by the trusts to purchase Floating Rate Notes issued by Mercantile. The rates of interest, interest payment dates, call features and maturity dates of each Floating Rate Note are identical to its respective Preferred Securities. The net proceeds from the issuance of the Floating Rate Notes were used for a variety of purposes, including contributions to the Bank as capital to provide support for asset growth and the funding of stock repurchase programs and certain acquisitions.
	The only significant assets of our trusts are the Floating Rate Notes, and the only significant liabilities of our trusts are the Preferred Securities. The Floating Rate Notes are categorized on our Consolidated Balance Sheets as subordinated debentures and the interest expense is recorded on our Consolidated Statements of Income under interest expense on other borrowings.
	The following table depicts our five business trusts as of December 31, 2014:
		Preferred
		Securities
	Trust Name	Outstanding	Interest Rate	Maturity Date
	Mercantile Bank Capital Trust I	$32,000,000	3 Month Libor + 218 bps	16-Sep-34
	Firstbank Capital Trust I	$10,000,000	3 Month Libor + 199 bps	18-Oct-34
	Firstbank Capital Trust II	$10,000,000	3 Month Libor + 127 bps	7-Apr-36
	Firstbank Capital Trust III	$7,500,000	3 Month Libor + 135 bps	30-Jul-37
	Firstbank Capital Trust IV	$7,500,000	3 Month Libor + 135 bps	30-Jul-37

Note_21_Regulatory_Matters

Note 21 - Regulatory Matters	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Regulatory Capital Requirements under Banking Regulations [Text Block]	NOTE 21 - REGULATORY MATTERS
	We are subject to regulatory capital requirements administered by federal banking agencies. Capital adequacy guidelines and prompt corrective action regulations involve quantitative measures of assets, liabilities, and certain off-balance sheet items calculated under regulatory accounting practices. Capital amounts and classifications are also subject to qualitative judgments by regulators about components, risk weightings, and other factors, and the regulators can lower classifications in certain cases. Failure to meet various capital requirements can initiate regulatory action that could have a direct material effect on the financial statements.
	The prompt corrective action regulations provide five classifications, including well capitalized, adequately capitalized, undercapitalized, significantly undercapitalized, and critically undercapitalized, although these terms are not used to represent overall financial condition. If an institution is not well capitalized, regulatory approval is required to accept brokered deposits. Subject to limited exceptions, no institution may make a capital distribution if, after making the distribution, it would be undercapitalized. If an institution is undercapitalized, it is subject to close monitoring by its principal federal regulator, its asset growth and expansion are restricted, and plans for capital restoration are required. In addition, further specific types of restrictions may be imposed on the institution at the discretion of the federal regulator. At year-end 2014 and 2013, our Bank was in the well capitalized category under the regulatory framework for prompt corrective action. There are no conditions or events since December 31, 2014 that we believe have changed our Bank’s categorization.
	Our actual capital levels (dollars in thousands) and minimum required levels were:
												Minimum Required
												to be Well
							Minimum Required					Capitalized Under
							for Capital					Prompt Corrective
		Actual					Adequacy Purposes					Action Regulations
		Amount		Ratio			Amount		Ratio			Amount		Ratio
	2014
	Total capital (to risk weighted assets)
	Consolidated	$	334,793		14.4	%	$	185,553		8	%	$	NA		NA
	Bank		332,749		14.4			185,309		8			231,636		10	%
	Tier 1 capital (to risk weighted assets)
	Consolidated		314,752		13.6			92,777		4			NA		NA
	Bank		312,708		13.5			92,655		4			138,982		6
	Tier 1 capital (to average assets)
	Consolidated		314,752		11.2			112,949		4			NA		NA
	Bank		312,708		11.1			112,856		4			141,070		5
	2013
	Total capital (to risk weighted assets)
	Consolidated	$	193,925		15.9	%	$	97,498		8	%	$	NA		NA
	Bank		190,493		15.7			97,329		8			121,662		10	%
	Tier 1 capital (to risk weighted assets)
	Consolidated		178,598		14.7			48,749		4			NA		NA
	Bank		175,192		14.4			48,665		4			72,997		6
	Tier 1 capital (to average assets)
	Consolidated		178,598		12.5			57,006		4			NA		NA
	Bank		175,192		12.3			56,860		4			71,075		5
	Federal and state banking laws and regulations place certain restrictions on the amount of dividends our Bank can transfer to Mercantile and on the capital levels that must be maintained. At year-end 2014, under the most restrictive of these regulations, our Bank could distribute approximately $87.7 million to Mercantile as dividends without prior regulatory approval.
	Our and our bank’s ability to pay cash and stock dividends is subject to limitations under various laws and regulations and to prudent and sound banking practices. On January 16, 2014, our Board of Directors declared a cash dividend on our common stock in the amount of $0.12 per share that was paid on March 10, 2014 to shareholders of record as of February 10, 2014. On May 9, 2014, our Board of Directors declared a cash dividend on our common stock in the amount of $0.12 per share that was paid on June 25, 2014 to shareholders of record as of June 13, 2014. On July 17, 2014, our Board of Directors declared a cash dividend on our common stock in the amount of $0.12 per share that was paid on September 24, 2014 to shareholders of record as of September 12, 2014. On October 16, 2014, our Board of Directors declared a cash dividend on our common stock in the amount of $0.12 per share that was paid on December 24, 2014 to shareholders of record as of December 12, 2014. In addition, on May 9, 2014, our Board of Directors declared a special cash dividend on our common stock in the amount of $2.00 per share that was paid on May 29, 2014 to shareholders of record as of May 22, 2014. The special cash dividend, in contemplation of the plan of merger with Firstbank, was paid to Mercantile shareholders prior to the effective date of the merger with Firstbank and before the issuance of Mercantile shares in exchange for Firstbank shares.
	On January 15, 2015, our Board of Directors declared a cash dividend on our common stock in the amount of $0.14 per share that will be paid on March 25, 2015 to shareholders of record as of March 13, 2015. In addition, on January 30, 2015, we announced that our Board of Directors had authorized a new program to repurchase up to $20.0 million of our common stock from time to time in open market transactions at prevailing market prices or by other means in accordance with applicable regulations. We expect to fund a majority of such repurchases from cash dividends paid to us from our Bank.
	Our consolidated capital levels as of December 31, 2014 and 2013 include $52.4 million and $32.0 million, respectively, of trust preferred securities subject to certain limitations. Under applicable Federal Reserve guidelines, the trust preferred securities constitute a restricted core capital element. The guidelines provide that the aggregate amount of restricted core elements that may be included in Tier 1 capital must not exceed 25% of the sum of all core capital elements, including restricted core capital elements, net of goodwill less any associated deferred tax liability. Our ability to include the trust preferred securities in Tier 1 capital in accordance with the guidelines is not affected by the provision of the Dodd-Frank Act generally restricting such treatment, because (i) the trust preferred securities were issued before May 19, 2010, and (ii) our total consolidated assets as of December 31, 2009 were less than $15.0 billion. At December 31, 2014 and 2013, all $52.4 million and $32.0 million, respectively, of the trust preferred securities were included as Tier 1 capital of Mercantile.

Note_22_US_Treasury_Capital_Pu

Note 22 - U.S. Treasury Capital Purchase Program Participation	12 Months Ended
	Dec. 31, 2014
US Treasury Capital Purchase Program Participation [Abstract]
US Treasury Capital Purchase Program Participation [Text Block]	NOTE 22 – U.S. TREASURY CAPITAL PURCHASE PROGRAM PARTICIPATION
	On May 15, 2009, we completed the sale of preferred stock and a warrant for common stock to the United States Treasury Department (“Treasury”) for $21.0 million under the Treasury’s Capital Purchase Program.  The program was designed to attract broad participation by healthy banking institutions to help stabilize the financial system and increase lending for the benefit of the U.S. economy.  Under the terms of the sale, the Treasury received 21,000 shares of fixed rate cumulative perpetual preferred stock with a liquidation value of $1,000 per share and a warrant to purchase 616,438 shares of our common stock, no par value, in exchange for $21.0 million.  The preferred stock qualified as Tier 1 capital and paid cumulative dividends at a rate of 5.00% for the first five years, and 9.00% thereafter.  The common stock warrant had a 10-year term and was immediately exercisable upon its issuance, with an exercise price equal to $5.11 per share.  The Treasury agreed not to exercise voting power with respect to any shares of common stock issued upon exercise of the warrant, while it held the shares.
	During the second quarter of 2012, we consummated the repurchase of the $21.0 million in preferred stock at par from the Treasury following approval from the Federal Reserve and consultation with the Federal Deposit Insurance Corporation.  To fund the repurchase, our bank paid us cash dividends aggregating approximately the same amount.  We recorded a reduction of retained earnings of approximately $0.6 million in the second quarter of 2012 resulting from the accelerated discount on the preferred stock which was being amortized over an original period of five years from the issuance date of May 15, 2009. During the third quarter of 2012, we consummated the repurchase of the warrant for approximately $7.5 million from the Treasury.  To fund the repurchase, our bank paid us a cash dividend of approximately the same amount. As part of the repurchase, we recorded a reduction in shareholders’ equity of approximately $7.5 million during the third quarter of 2012.

Note_23_Accumulated_Other_Comp

Note 23 - Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Comprehensive Income (Loss) Note [Text Block]	NOTE 23 – ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)
	At December 31, 2014, accumulated other comprehensive loss, net of tax effects (as applicable), consists of a net unrealized gain on available for sale securities of $0.2 million and the fair value of an interest rate swap of negative $0.2 million. At December 31, 2013, accumulated other comprehensive income, net of tax effects (as applicable), consists of a net unrealized loss on available for sale securities of $5.4 million and the fair value of an interest rate swap of negative $0.2 million. At December 31, 2012, accumulated other comprehensive income, net of tax effects (as applicable), consists of a net unrealized gain on available for sale securities of $2.4 million and the fair value of an interest rate swap of negative $0.7 million.

Note_24_Quarterly_Financial_Da

Note 24 - Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	NOTE 24 - QUARTERLY FINANCIAL DATA (Unaudited)
		Interest		Net Interest		Net		Earnings per Share
		Income		Income		Income		Basic		Diluted
	2014
	First quarter	$	13,588,000	$	11,064,000	$	3,580,000	$	0.41	$	0.41
	Second quarter		18,483,000		15,552,000		1,510,000		0.13		0.13
	Third quarter		28,900,000		25,989,000		5,948,000		0.35		0.35
	Fourth quarter		28,147,000		25,173,000		6,293,000		0.37		0.37
	2013
	First quarter	$	14,210,000	$	11,455,000	$	4,401,000	$	0.51	$	0.5
	Second quarter		13,992,000		11,312,000		4,016,000		0.46		0.46
	Third quarter		14,667,000		11,994,000		3,453,000		0.4		0.4
	Fourth quarter		15,373,000		12,695,000		5,163,000		0.59		0.59

Note_25_Mercantile_Bank_Corpor

Note 25 - Mercantile Bank Corporation (Parent Company Only) Condensed Financial Statements	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Financial Information of Parent Company Only Disclosure [Text Block]	NOTE 25 – MERCANTILE BANK CORPORATION (PARENT COMPANY ONLY)
	CONDENSED FINANCIAL STATEMENTS
	CONDENSED BALANCE SHEETS
		2014			2013
	ASSETS
	Cash and cash equivalents	$	1,441,000		$	2,506,000
	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
	CONDENSED STATEMENTS OF INCOME
		2014			2013			2012
	Income
	Interest and dividends from subsidiaries	$	12,139,000		$	5,516,000		$	32,532,000
	Total income		12,139,000			5,516,000			32,532,000
	Expenses
	Interest expense		2,145,000			1,213,000			884,000
	Other operating expenses		3,552,000			2,773,000			1,048,000
	Total expenses		5,697,000			3,986,000			1,932,000
	Income before income tax benefit and equity in undistributed net income (loss) of subsidiary		6,442,000			1,530,000			30,600,000
	Federal income tax benefit		(1,758,000	)		(1,042,000	)		(665,000	)
	Equity in undistributed net income (loss) of subsidiary		9,131,000			14,461,000			(18,730,000	)
	Net income		17,331,000			17,033,000			12,535,000
	Preferred stock dividends and accretion		0			0			1,030,000
	Net income attributable to common shares	$	17,331,000		$	17,033,000		$	11,505,000
	Comprehensive income	$	22,920,000		$	9,810,000		$	10,857,000
	CONDENSED STATEMENTS OF CASH FLOWS
		2014			2013			2012
	Cash flows from operating activities
	Net income	$	17,331,000		$	17,033,000		$	12,535,000
	Adjustments to reconcile net income to net cash from operating activities:
	Equity in undistributed (income) loss of subsidiary		(9,131,000	)		(14,461,000	)		18,730,000
	Stock-based compensation expense		714,000			473,000			54,000
	Change in other assets		(8,163,000	)		3,244,000			(3,006,000	)
	Change in other liabilities		21,979,000			(708,000	)		1,073,000
	Net cash from operating activities		22,730,000			5,581,000			29,386,000
	Cash flows from investing activities
	Net capital investment into subsidiaries		0			0			0
	Net cash for investing activities		0			0			0
	Cash flows from financing activities
	Repurchase of preferred stock		0			0			(21,000,000	)
	Repurchase of common stock warrant		0			0			(7,465,000	)
	Stock option exercises, net of cashless exercises		282,000			289,000			227,000
	Employee stock purchase plan		23,000			19,000			39,000
	Dividend reinvestment plan		209,000			33,000			14,000
	Stock grants to directors for retainer fees		155,000			0			0
	Cash dividends on preferred stock		0			0			(496,000	)
	Cash dividends on common stock		(24,464,000	)		(3,889,000	)		(774,000	)
	Net cash for financing activities		(23,795,000	)		(3,548,000	)		(29,455,000	)
	Net change in cash and cash equivalents		(1,065,000	)		2,033,000			(69,000	)
	Cash and cash equivalents at beginning of period		2,506,000			473,000			542,000
	Cash and cash equivalents at end of period	$	1,441,000		$	2,506,000		$	473,000

Accounting_Policies_by_Policy_

Accounting Policies, by Policy (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Consolidation, Policy [Policy Text Block]	Principles of Consolidation: The consolidated financial statements include the accounts of Mercantile Bank Corporation (“Mercantile”) and its subsidiary, Mercantile Bank of Michigan (“Bank”), and of Mercantile Bank Real Estate Co., L.L.C. (“Mercantile Real Estate”) and Mercantile Insurance Center, Inc. (“Mercantile Insurance”), subsidiaries of our Bank, after elimination of significant intercompany transactions and accounts.
	We have five separate business trusts: Mercantile Bank Capital Trust I, Firstbank Capital Trust I, Firstbank Capital Trust II, Firstbank Capital Trust III and Firstbank Capital Trust IV (“our trusts”). Our trusts were formed to issue trust preferred securities. We issued subordinated debentures to our trusts in return for the proceeds raised from the issuance of the trust preferred securities. Our trusts are not consolidated, but instead we report the subordinated debentures issued to the trusts as liabilities.
Nature of Operation [Policy Text Block]	Nature of Operations: Mercantile was incorporated on July 15, 1997 to establish and own the Bank based in Grand Rapids, Michigan. The Bank began operations on December 15, 1997. We completed the merger of Firstbank Corporation (“Firstbank”), a Michigan corporation with approximately $1.5 billion in total assets and 46 branch locations, into Mercantile as of June 1, 2014.
	The Bank is a community-based financial institution. The Bank’s primary deposit products are checking, savings, and term certificate accounts, and its primary lending products are commercial loans, residential mortgage loans, and instalment loans. Substantially all loans are secured by specific items of collateral including business assets, real estate or consumer assets. Commercial loans are expected to be repaid from cash flow from operations of businesses. Real estate loans are secured by commercial or residential real estate. The Bank’s loan accounts and retail deposits are primarily with customers located in the communities in which we have bank office locations. As an alternative source of funds, the Bank has also issued certificates of deposit to depositors outside of its primary market areas. Substantially all revenues are derived from banking products and services and investment securities. While we monitor the revenue streams of the various products and services offered, we manage our business on the basis of one operating segment, banking.
	Mercantile Insurance was formed during 2002 through the acquisition of an existing shelf insurance agency. Insurance products are offered through an Agency and Institutions Agreement among Mercantile Insurance, the Bank and Hub International. The insurance products are marketed through a central facility operated by the Michigan Bankers Insurance Association, members of which include the insurance subsidiaries of various Michigan-based financial institutions and Hub International. Mercantile Insurance receives commissions based upon written premiums produced under the Agency and Institutions Agreement.
	Mercantile Real Estate was organized on July 21, 2003, principally to develop, construct, and own a facility in downtown Grand Rapids that serves as our Bank’s main office and Mercantile’s headquarters. This facility was placed into service during the second quarter of 2005.
Use of Estimates, Policy [Policy Text Block]	Use of Estimates: To prepare financial statements in conformity with accounting principles generally accepted in the United States of America, management makes estimates and assumptions based on available information. These estimates and assumptions affect the amounts reported in the financial statements and the disclosures provided, and actual results could differ. The allowance for loan losses and the fair values of financial instruments are particularly subject to change.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash Flow Reporting: Cash and cash equivalents include cash on hand, demand deposits with other financial institutions, short-term investments (including securities with daily put provisions) and federal funds sold. Cash flows are reported net for customer loan and deposit transactions, interest-bearing time deposits with other financial institutions and short-term borrowings with maturities of 90 days or less.
Marketable Securities, Policy [Policy Text Block]	Securities: Debt securities classified as held to maturity are carried at amortized cost when management has the positive intent and ability to hold them to maturity. Debt securities are classified as available for sale when they might be sold prior to maturity. Equity securities with readily determinable fair values are classified as available for sale. Securities available for sale are carried at fair value, with unrealized holding gains and losses reported in other comprehensive income, net of tax. Federal Home Loan Bank stock is carried at cost.
	Interest income includes amortization of purchase premiums and accretion of discounts. Premiums and discounts on securities are amortized or accreted on the level-yield method without anticipating prepayments, except for mortgage-backed securities where prepayments are anticipated. Gains and losses on sales are recorded on the trade date and determined using the specific identification method.
	Declines in the fair value of debt securities below their amortized cost that are other than temporary (“OTTI”) are reflected in earnings or other comprehensive income, as appropriate. For those debt securities whose fair value is less than their amortized cost, we consider our intent to sell the security, whether it is more likely than not that we will be required to sell the security before recovery and whether we expect to recover the entire amortized cost of the security based on our assessment of the issuer’s financial condition. In analyzing an issuer’s financial condition, we consider whether the securities are issued by the federal government or its agencies, and whether downgrades by bond rating agencies have occurred. If either of the criteria regarding intent or requirement to sell is met, the entire difference between amortized cost and fair value is recognized as impairment through earnings. For debt securities that do not meet the aforementioned criteria, the amount of impairment is split into two components as follows: 1) OTTI related to credit loss, which must be recognized in the income statement, and 2) OTTI related to other factors, such as liquidity conditions in the market or changes in market interest rates, which is recognized in other comprehensive income. The credit loss is defined as the difference between the present value of the cash flows expected to be collected and the amortized cost.
Finance, Loan and Lease Receivables, Held-for-investment, Policy [Policy Text Block]	Loans: Loans that we have the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at the principal balance outstanding, net of deferred loan fees and costs and an allowance for loan losses. Interest income is accrued on the unpaid principal balance. Loan origination fees, net of certain direct origination costs, are deferred and recognized in interest income using the level-yield method without anticipating prepayments. Net unamortized deferred loan fees amounted to $1.1 million and $0.5 million at December 31, 2014 and 2013, respectively.
	Interest income on commercial loans and mortgage loans is discontinued at the time the loan is 90 days delinquent unless the loan is well-secured and in process of collection. Consumer and credit card loans are typically charged off no later than when they are 120 days past due. Past due status is based on the contractual terms of the loan. In all cases, loans are placed on nonaccrual or charged off at an earlier date if collection of principal and interest is considered doubtful.
	All interest accrued but not received for loans placed on nonaccrual is reversed against interest income. Interest received on such loans is accounted for on the cash-basis or cost-recovery method, until qualifying for return to accrual. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured.
Finance, Loan and Lease Receivables, Held-for-sale, Policy [Policy Text Block]	Loans Held for Sale: Mortgage loans originated and intended for sale in the secondary market are carried at the lower of aggregate cost or fair value, as determined by outstanding commitments from investors. Net unrealized losses, if any, are recorded as a valuation allowance and charged to earnings. Prior to the merger with Firstbank, such mortgage loans were sold servicing released. Subsequent to the merger, mortgage loans held for sale are generally sold with servicing rights retained. Gains and losses on sales of mortgage loans are based on the difference between the selling price and the carrying value of the related mortgage loan sold, which is reduced by the cost allocated to the servicing right. We generally lock in the sale price to the purchaser of the mortgage loan at the same time we make an interest rate commitment to the borrower.
	Year-end mortgage loans held for sale were as follows:
		2014		2013
	Mortgage loans held for sale	$	1,574,000	$	1,115,000
	Less: Allowance to adjust to lower of cost or market		0		0
	Mortgage loans held for sale, net	$	1,574,000	$	1,115,000
Mortgage Loan Derivatives [Policy Text Block]	Mortgage Loan Derivatives: From time to time, we enter into mortgage loan derivatives such as forward contracts and interest rate lock commitments in the ordinary course of business. The derivatives are not designated as hedges and are carried at fair value. The net gain or loss on mortgage loan derivatives is included in mortgage banking activities in the income statement. The balance of mortgage loan derivatives was immaterial at December 31, 2014 and 2013.
Loans and Leases Receivable, Mortgage Banking Activities, Policy [Policy Text Block]	Mortgage Banking Activities: Mortgage loan servicing rights are recognized as assets based on the allocated value of retained servicing rights on mortgage loans sold. Mortgage loan servicing rights are carried at the lower of amortized cost or fair value and are expensed in proportion to, and over the period of, estimated net servicing revenues. Impairment is evaluated based on the fair value of the rights using groupings of the underlying mortgage loans as to interest rates. Any impairment of a grouping is reported as a valuation allowance.
	Servicing fee income is recorded for fees earned for serving mortgage loans. The fees are based on a contractual percentage of the outstanding principal or a fixed amount per loan and are recorded as income when earned. Amortization of mortgage loan servicing rights is netted against mortgage loan servicing income and recorded in mortgage banking activities in the income statement.
Loans and Leases Receivable, Troubled Debt Restructuring Policy [Policy Text Block]	Troubled Debt Restructurings: A loan is accounted for as a troubled debt restructuring if we, for economic or legal reasons, grant a concession to a borrower considered to be experiencing financial difficulties that we would not otherwise consider. A troubled debt restructuring may involve the receipt of assets from the debtor in partial or full satisfaction of the loan, or a modification of terms such as a reduction of the stated interest rate or balance of the loan, a reduction of accrued interest, an extension of the maturity date or renewal of the loan at a stated interest rate lower than the current market rate for a new loan with similar risk, or some combination of these concessions. Troubled debt restructurings can be in either accrual or nonaccrual status. Nonaccrual troubled debt restructurings are included in nonperforming loans. Accruing troubled debt restructurings are generally excluded from nonperforming loans as it is considered probable that all contractual principal and interest due under the restructured terms will be collected.
	Loans modified as troubled debt restructurings are, by definition, considered to be impaired loans. Impairment for these loans is measured on a loan-by-loan basis similar to other impaired loans as described below under “Allowance for Loan Losses.” Certain loans modified as troubled debt restructurings may have been previously measured for impairment under a general allowance methodology (i.e., pooling), thus at the time the loan is modified as a troubled debt restructuring the allowance will be impacted by the difference between the results of these two measurement methodologies. Loans modified as troubled debt restructurings that subsequently default are factored into the determination of the allowance for loan losses in the same manner as other defaulted loans.
Loans and Leases Receivable, Allowance for Loan Losses Policy [Policy Text Block]	Allowance for Loan Losses: The allowance for loan losses (“allowance”) is a valuation allowance for probable incurred credit losses. Loan losses are charged against the allowance when we believe the uncollectability of a loan is confirmed. Subsequent recoveries, if any, are credited to the allowance. We estimate the allowance balance required using past loan loss experience, the nature and volume of the loan portfolio, information about specific borrower situations and estimated collateral values, economic conditions and other factors. We estimate credit losses based on individual loans determined to be impaired and on all other loans grouped on similar risk characteristics. Our historical loss component is the most significant of the allowance components and is based on historical loss experience by credit risk grade for commercial loans and payment status for mortgage and consumer loans. Loans are pooled based on similar risk characteristics supported by observable data. The historical loss experience component of the allowance represents the results of migration analysis of historical net charge-offs for portfolios of loans, including groups of commercial loans within each credit risk grade. For measuring loss exposure in a pool of loans, the historical net charge-off or migration experience is utilized to estimate expected future losses to be realized from the pool of loans. Allocations of the allowance may be made for specific loans, but the entire allowance is available for any loan that, in our judgment, should be charged-off.
	A loan is considered impaired when, based on current information and events, it is probable we will be unable to collect the scheduled payments of principal and interest when due according to the contractual terms of the loan agreement. Factors considered in determining impairment include payment status and collateral value. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired. We determine the significance of payment delays and payment shortfalls on a case-by-case basis, taking into consideration all of the circumstances surrounding the loan and the borrower, including the length of delay, the reasons for delay, the borrower’s prior payment record and the amount of the shortfall in relation to the principal and interest owed. Impairment is measured on a loan-by-loan basis for commercial and construction loans by the present value of expected future cash flows discounted at the loan’s effective interest rate, the loan’s obtainable market price or the fair value of collateral if the loan is collateral dependent. Large groups of smaller balance homogeneous loans are collectively evaluated for impairment.
Transfers and Servicing of Financial Assets, Policy [Policy Text Block]	Transfers of Financial Assets: Transfers of financial assets are accounted for as sales when control over the assets has been surrendered. Control over transferred assets is deemed to be surrendered when: (1) the assets have been isolated from the Bank and put presumptively beyond the reach of the transferor and its creditors, even in bankruptcy or other receivership, (2) the transferee obtains the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred assets, and (3) the Bank does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity or the ability to unilaterally cause the holder to return specific assets. Our transfers of financial assets are generally limited to commercial loan participations sold and residential mortgage loans sold in the secondary market.
Property, Plant and Equipment, Policy [Policy Text Block]	Premises and Equipment: Land is carried at cost. Premises and equipment are stated at cost less accumulated depreciation. Buildings and related components are depreciated using the straight-line method with useful lives ranging from 5 to 33 years. Furniture, fixtures and equipment are depreciated using the straight-line method with useful lives ranging from 3 to 7 years. Maintenance, repairs and minor alterations are charged to current operations as expenditures occur and major improvements are capitalized.
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]	Long-lived Assets: Premises and equipment and other long-lived assets are reviewed for impairment when events indicate their carrying amount may not be recoverable based on future undiscounted cash flows. If impaired, the assets are recorded at the lower of carrying value or fair value.
Finance, Loan and Lease Receivables, Held for Investments, Foreclosed Assets Policy [Policy Text Block]	Foreclosed Assets: Assets acquired through or in lieu of foreclosure are initially recorded at their estimated fair value net of estimated selling costs, establishing a new cost basis. If fair value subsequently declines, a valuation allowance is recorded through noninterest expense, as are collection and operating costs after acquisition. Foreclosed assets totaled $2.0 million and $2.9 million as of December 31, 2014 and 2013, respectively.
Bank Owned Life Insurance [Policy Text Block]	Bank Owned Life Insurance: The Bank has purchased life insurance policies on certain key officers. Bank owned life insurance is recorded at its cash surrender value, or the amount that can be realized.
Goodwill and Intangible Assets, Policy [Policy Text Block]	Goodwill and Core Deposit Intangible: Goodwill results from business acquisitions and represents the excess of the purchase price over the fair value of acquired tangible assets and liabilities and identifiable intangible assets. Goodwill is assessed at least annually for impairment and any such impairment is recognized in the period identified. A more frequent assessment is performed should events or changes in circumstances indicate the carrying value of the goodwill may not be recoverable. We may elect to perform a qualitative assessment for the annual impairment test. If the qualitative assessment indicates it is more likely than not that the fair value of a reporting unit is less than its carrying amount, or if we elect not to perform a qualitative assessment, then we would be required to perform a quantitative test for goodwill impairment. The quantitative test is a two-step process consisting of comparing the carrying value of the reporting unit to an estimate of its fair value. If the estimated fair value of the reporting unit is less than the carrying value, goodwill is impaired and is written down to its estimated fair value. In 2014, we elected to perform a qualitative assessment for our annual impairment test and concluded our fair value was greater than its carrying amount; therefore, no further testing was required.
	The core deposit intangible that arose from the merger with Firstbank was initially measured at fair value and is being amortized into noninterest expense over a ten-year period using the sum-of-the-years-digits methodology.
Repurchase and Resale Agreements Policy [Policy Text Block]	Repurchase Agreements: The Bank sells certain securities under agreements to repurchase. The agreements are treated as collateralized financing transactions, with the obligations to repurchase the securities sold reflected as liabilities and the securities underlying the agreements remaining in assets in the Consolidated Balance Sheets.
Off-Balance-Sheet Credit Exposure, Policy [Policy Text Block]	Financial Instruments and Loan Commitments: Financial instruments include off-balance-sheet credit instruments, such as commitments to make loans and commercial letters of credit, issued to meet customer financing needs. The face amount for these items represents the exposure to loss, before considering customer collateral or ability to repay. Such financial instruments are recorded when they are funded. Instruments, such as standby letters of credit, that are considered financial guarantees are recorded at fair value.
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]	Stock-Based Compensation: Compensation cost for equity-based awards is measured on the grant date based on the fair value of the award at that date, and is recognized over the requisite service period, net of estimated forfeitures. Fair value of stock option awards is estimated using a closed option valuation (Black-Scholes) model. Fair value of restricted stock awards is based upon the quoted market price of the common stock on the date of grant.
Advertising Costs, Policy [Policy Text Block]	Advertising Costs: Advertising costs are expensed as incurred.
Income Tax, Policy [Policy Text Block]	Income Taxes: Income tax expense is the total of the current year income tax due or refundable, the change in deferred income tax assets and liabilities, and any adjustments related to unrecognized tax benefits. Deferred income tax assets and liabilities are recognized for the tax consequences of temporary differences between the carrying amounts and tax bases of assets and liabilities, computed using enacted tax rates applicable to future years. A valuation allowance, if needed, reduces deferred income tax assets to the amount expected to be realized.
Fair Value of Financial Instruments, Policy [Policy Text Block]	Fair Values of Financial Instruments: Fair values of financial instruments are estimated using relevant market information and other assumptions. Fair value estimates involve uncertainties and matters of significant judgment regarding interest rates, credit risk, prepayments and other factors, especially in the absence of broad markets for particular items. Changes in assumptions or in market conditions could significantly affect the estimates. The fair value estimates of existing on- and off-balance sheet financial instruments do not include the value of anticipated future business or the values of assets and liabilities not considered financial instruments.
Earnings Per Share, Policy [Policy Text Block]	Earnings Per Share: Basic earnings per share is based on the weighted average number of common shares and participating securities outstanding during the period. Diluted earnings per share include the dilutive effect of additional potential common shares issuable under our stock-based compensation plans using the treasury stock method. In addition, diluted earnings per share for 2012 include the dilutive effect of our common stock warrant granted to the U.S. Department of Treasury that we repurchased on July 3, 2012, also using the treasury stock method. Our unvested stock awards, which contain non-forfeitable rights to dividends whether paid or unpaid (i.e., participating securities), are included in the number of shares outstanding for both basic and diluted earnings per share calculations. In the event of a net loss, our unvested stock awards are excluded from the calculations of both basic and diluted earnings per share.
Comprehensive Income, Policy [Policy Text Block]	Comprehensive Income: Comprehensive income consists of net income and other comprehensive income (loss). Other comprehensive income (loss) includes unrealized gains and losses on securities available for sale and interest rate swaps which are also recognized as a separate component of equity.
Derivatives, Policy [Policy Text Block]	Derivatives: Derivative financial instruments are recognized as assets or liabilities at fair value. The accounting for changes in the fair value of derivatives depends on the use of the derivatives and whether the derivatives qualify for hedge accounting. Used as part of our asset and liability management to help manage interest rate risk, our derivatives have historically generally consisted of interest rate swap agreements that qualified for hedge accounting. We do not use derivatives for trading purposes.
	Changes in the fair value of derivatives that are designated, for accounting purposes, as a hedge of the variability of cash flows to be received on various assets and liabilities and are effective are reported in other comprehensive income. They are later reclassified into earnings in the same periods during which the hedged transaction affects earnings and are included in the line item in which the hedged cash flows are recorded. If hedge accounting does not apply, changes in the fair value of derivatives are recognized immediately in current earnings as interest income or expense.
	If designated as a hedge, we formally document the relationship between the derivative instrument and the hedged item, as well as the risk-management objective and the strategy for undertaking the hedge transaction. This documentation includes linking cash flow hedges to specific assets on the balance sheet. If designated as a hedge, we also formally assess, both at the hedge’s inception and on an ongoing basis, whether the derivative instrument that is used is highly effective in offsetting changes in cash flows of the hedged items. Ineffective hedge gains and losses are recognized immediately in current earnings as noninterest income or expense. We discontinue hedge accounting when we determine the derivative is no longer effective in offsetting changes in the cash flows of the hedged item, the derivative is settled or terminates, or treatment of the derivatives as a hedge is no longer appropriate or intended.
Commitments and Contingencies, Policy [Policy Text Block]	Contingencies: Loss contingencies, including claims and legal actions arising in the ordinary course of business, are recorded as liabilities when the likelihood of loss is probable and an amount or range of loss can be reasonably estimated. We do not believe there are any such matters outstanding that would have a material effect on the financial statements.
Reclassification, Policy [Policy Text Block]	Reclassifications: Certain items in the prior years’ financial statements have been reclassified to conform to the current year presentation.
New Accounting Pronouncements, Policy [Policy Text Block]	Accounting Standards Updates: In January of 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-04, Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure. This ASU clarifies that an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. The ASU also requires additional related interim and annual disclosures. The guidance in this ASU is effective for annual and interim periods beginning after December 15, 2014, and is not expected to have a material effect on our financial position or results of operations when adopted.
	In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. This ASU establishes a comprehensive revenue recognition standard for virtually all industries under U.S. GAAP, including those that previously followed industry-specific guidance such as the real estate, construction and software industries. The revenue standard’s core principle is built on the contract between a vendor and a customer for the provision of goods and services. It attempts to depict the exchange of rights and obligations between the parties in the pattern of revenue recognition based on the consideration to which the vendor is entitled. To accomplish this objective, the standard requires five basic steps: i) identify the contract with the customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract, and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The guidance in this ASU is effective for annual and interim periods beginning after December 15, 2016, with three transition methods available – full retrospective, retrospective and cumulative effect approach. Although we are in process of evaluating the impact, the adoption of this ASU is not expected to have a material effect on our financial position or results of operations.
	In June 2014, the FASB issued ASU 2014-11, Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures. This ASU requires two accounting changes. First, repurchase-to-maturity transactions will be accounted for as secured borrowing transactions on the balance sheet, rather than sales. Second, for repurchase financing arrangements, the ASU requires separate accounting for a transfer of a financial asset executed contemporaneously with (or in contemplation of) a repurchase agreement with the same counterparty, which also will generally result in secured borrowing accounting for the repurchase agreement. The ASU also introduces new disclosures to increase transparency about the types of collateral pledged for repurchase agreements, securities lending transactions, and repurchase-to-maturity transactions that are accounted for as secured borrowings. The ASU also requires a transferor to disclose information about transactions accounted for as a sale in which the transferor retains substantially all of the exposure to the economic return on the transferred financial assets through an agreement with the transferee. The accounting changes and disclosure for certain transactions accounted for as a sale are effective for the first annual and interim periods beginning after December 15, 2014. The disclosure for transactions accounted for as secured borrowings is required for annual periods beginning after December 15, 2014, and for interim periods beginning after March 15, 2015. Adoption of this ASU is not expected to have a material effect on our financial position or results of operations.
	In August 2014, the FASB issued ASU 2014-14, Classification of Certain Government-Guaranteed Mortgage Loans Upon Foreclosure. This ASU requires that certain government-guaranteed mortgage loans, including those guaranteed by the Federal Housing Administration, be derecognized and that a separate other receivable be recognized upon foreclosure if certain conditions are met. Upon foreclosure on the loans that meet these criteria, a separate receivable should be recorded based on the amount of the loan balance expected to be recovered from the guarantor. The guidance in this ASU is effective for annual and interim periods beginning after December 15, 2014, and is not expected to have a material effect on our financial position or results of operations when adopted.

Note_1_Summary_of_Significant_1

Note 1 - Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Mortgage Loans Held for Sale [Table Text Block]		2014		2013
	Mortgage loans held for sale	$	1,574,000	$	1,115,000
	Less: Allowance to adjust to lower of cost or market		0		0
	Mortgage loans held for sale, net	$	1,574,000	$	1,115,000

Note_2_Business_Combination_Ta

Note 2 - Business Combination (Tables)	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Schedule of Business Acquisitions by Acquisition, Equity Interest Issued or Issuable [Table Text Block]	Purchase Price:
	Mercantile common shares issued for Firstbank common shares		8,087,272
	Price per share, based on Mercantile closing price on May 30, 2014	$	21.43
	Value of common stock issued		173,310,000
	Value of replacement stock options granted		1,664,000
	Total purchase price	$	174,974,000
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	Preliminary Statement of Net Assets Acquired at Fair Value:
	Assets
	Cash and cash equivalents	$	91,806,000
	Securities		358,599,000
	Total loans		943,662,000
	Premises and equipment		24,049,000
	Core deposit intangible		17,478,000
	Mortgage servicing rights		7,389,000
	Other assets		9,897,000
	Total Assets	$	1,452,880,000
	Liabilities
	Deposits	$	1,229,609,000
	Borrowings		87,615,000
	Other liabilities		10,155,000
	Total Liabilities	$	1,327,379,000
	Net Identifiable Assets Acquired			$	125,501,000
	Goodwill			$	49,473,000
Business Acquisition, Pro Forma Information [Table Text Block]		2014		2013
	Net interest income	$	98,607,000	$	93,862,000
	Noninterest expense		81,295,000		93,263,000
	Net income		22,659,000		16,068,000
	Net income per diluted share		1.33		0.96
Business Acquisition, Fair Value of Loans Acquired [Table Text Block]		Acquired		Acquired		Acquired
		Impaired		Non-Impaired		Total Loans
	Commercial Loans:
	Commercial & industrial	$	878,000	$	163,316,000	$	164,194,000
	Commercial real estate		12,973,000		378,016,000		390,989,000
	Construction & development		1,289,000		33,726,000		35,015,000
	Total Commercial Loans	$	15,140,000	$	575,058,000	$	590,198,000
	Consumer Loans:
	Residential mortgages	$	9,694,000	$	216,653,000	$	226,347,000
	Instalment		167,000		61,657,000		61,824,000
	Home equity lines		288,000		52,054,000		52,342,000
	Construction		76,000		12,875,000		12,951,000
	Total Consumer Loans	$	10,225,000	$	343,239,000	$	353,464,000
	Total Loans	$	25,365,000	$	918,297,000	$	943,662,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Table Text Block]		Acquired Impaired
	Contractually required payments	$	44,936,000
	Nonaccretable difference		17,057,000
	Expected cash flows		27,879,000
	Accretable yield		2,514,000
	Carrying balance	$	25,365,000

Note_3_Securities_Tables

Note 3 - Securities (Tables)	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities [Table Text Block]					Gross		Gross
		Amortized			Unrealized		Unrealized			Fair
		Cost			Gains		Losses			Value
	2014
	U.S. Government agency debt obligations	$	194,894,000		$	1,612,000	$	(3,038,000	)	$	193,468,000
	Mortgage-backed securities		92,656,000			1,123,000		(218,000	)		93,561,000
	Municipal general obligation bonds		132,347,000			1,042,000		(307,000	)		133,082,000
	Municipal revenue bonds		10,769,000			117,000		(13,000	)		10,873,000
	Other investments		1,925,000			3,000		0			1,928,000
		$	432,591,000		$	3,897,000	$	(3,576,000	)	$	432,912,000
	2013
	U.S. Government agency debt obligations	$	108,279,000		$	263,000	$	(10,065,000	)	$	98,477,000
	Mortgage-backed securities		12,456,000			1,102,000		0			13,558,000
	Municipal general obligation bonds		16,488,000			388,000		(4,000	)		16,872,000
	Municipal revenue bonds		878,000			38,000		0			916,000
	Mutual funds		1,386,000			0		(31,000	)		1,355,000
		$	139,487,000		$	1,791,000	$	(10,100,000	)	$	131,178,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Table Text Block]		Less than 12 Months					12 Months or More					Total
		Fair			Unrealized		Fair			Unrealized		Fair		Unrealized
	Description of Securities	Value			Loss		Value			Loss		Value		Loss
	2014
	U.S. Government agency debt obligations	$	81,891,000		$	202,000	$	74,120,000		$	2,836,000	$	156,011,000	$	3,038,000
	Mortgage-backed securities		49,940,000			218,000		0			0		49,940,000		218,000
	Municipal general obligation bonds		54,104,000			307,000		0			0		54,104,000		307,000
	Municipal revenue bonds		4,644,000			13,000		0			0		4,644,000		13,000
	Other investments		0			0		0			0		0		0
		$	190,579,000		$	740,000	$	74,120,000		$	2,836,000	$	264,699,000	$	3,576,000
	2013
	U.S. Government agency debt obligations	$	57,117,000		$	5,798,000	$	29,679,000		$	4,267,000	$	86,796,000	$	10,065,000
	Mortgage-backed securities		0			0		0			0		0		0
	Municipal general obligation bonds		295,000			4,000		0			0		295,000		4,000
	Municipal revenue bonds		0			0		0			0		0		0
	Mutual funds		1,355,000			31,000		0			0		1,355,000		31,000
		$	58,767,000		$	5,833,000	$	29,679,000		$	4,267,000	$	88,446,000	$	10,100,000
Investments Classified by Contractual Maturity Date [Table Text Block]		Weighted
		Average			Amortized		Fair
		Yield			Cost		Value
	Due in one year or less		0.72	%	$	27,651,000	$	27,662,000
	Due from one to five years		1.35			148,233,000		147,974,000
	Due from five to ten years		2.99			70,282,000		70,191,000
	Due after ten years		3.62			91,844,000		91,596,000
	Mortgage-backed securities		1.79			92,656,000		93,561,000
	Other investments		2.57			1,925,000		1,928,000
			2.17	%	$	432,591,000	$	432,912,000

Note_4_Loans_and_Allowance_for1

Note 4 - Loans and Allowance for Loan Losses (Tables)	12 Months Ended
	Dec. 31, 2014
Note 4 - Loans and Allowance for Loan Losses (Tables) [Line Items]
Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]														Percent
		31-Dec-14						31-Dec-13						Increase
		Balance			%			Balance			%			(Decrease)
	Originated Loans
	Commercial:
	Commercial and industrial	$	384,570,000			30.8	%	$	286,373,000			27.2	%		34.3	%
	Vacant land, land development, and residential construction		29,826,000			2.4			36,741,000			3.5			(18.8	)
	Real estate – owner occupied		291,758,000			23.4			261,877,000			24.9			11.4
	Real estate – non-owner occupied		410,977,000			33			364,066,000			34.6			12.9
	Real estate – multi-family and residential rental		36,058,000			2.9			37,639,000			3.5			(4.2	)
	Total commercial		1,153,189,000			92.5			986,696,000			93.7			16.9
	Retail:
	Home equity and other		50,059,000			4			35,080,000			3.3			42.7
	1-4 family mortgages		42,868,000			3.5			31,467,000			3			36.2
	Total retail		92,927,000			7.5			66,547,000			6.3			39.6
	Total originated loans	$	1,246,116,000			100	%	$	1,053,243,000			100	%		18.3	%
														Percent
		31-Dec-14						31-Dec-13						Increase
		Balance			%			Balance			%			(Decrease)
	Acquired Loans
	Commercial:
	Commercial and industrial	$	166,037,000			19.7	%	$	0			NA			NM
	Vacant land, land development, and residential construction		22,148,000			2.6			0			NA			NM
	Real estate – owner occupied		138,630,000			16.4			0			NA			NM
	Real estate – non-owner occupied		148,597,000			17.6			0			NA			NM
	Real estate – multi-family and residential rental		86,702,000			10.3			0			NA			NM
	Total commercial		562,114,000			66.6			0			NA			NM
	Retail:
	Home equity and other		109,219,000			13			0			NA			NM
	1-4 family mortgages		171,828,000			20.4			0			NA			NM
	Total retail		281,047,000			33.4			0			NA			NM
	Total acquired loans	$	843,161,000			100	%	$	0			NA			NM
														Percent
		31-Dec-14						31-Dec-13						Increase
		Balance			%			Balance			%			(Decrease)
	Total Loans
	Commercial:
	Commercial and industrial	$	550,607,000			26.4	%	$	286,373,000			27.2	%		92.3	%
	Vacant land, land development, and residential construction		51,974,000			2.5			36,741,000			3.5			41.5
	Real estate – owner occupied		430,388,000			20.5			261,877,000			24.9			64.3
	Real estate – non-owner occupied		559,574,000			26.8			364,066,000			34.6			53.7
	Real estate – multi-family and residential rental		122,760,000			5.9			37,639,000			3.5			226.2
	Total commercial		1,715,303,000			82.1			986,696,000			93.7			73.8
	Retail:
	Home equity and other		159,278,000			7.6			35,080,000			3.3			354
	1-4 family mortgages		214,696,000			10.3			31,467,000			3			582.3
	Total retail		373,974,000			17.9			66,547,000			6.3			462
	Total loans	$	2,089,277,000			100	%	$	1,053,243,000			100	%		98.4	%
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Accretable Yield Movement [Table Text Block]		2014
	Balance at May 31, 2014	$	0
	Additions		2,514,000
	Accretion		(786,000	)
	Net reclassification from nonaccretable to accretable		3,537,000
	Disposals		(40,000	)
	Other activity		(227,000	)
	Balance at December 31, 2014	$	4,998,000
Concentrations Within Loan Portfolio [Table Text Block]		2014						2013
					Percentage of						Percentage of
		Balance			Loan Portfolio			Balance			Loan Portfolio
	Commercial real estate loans to lessors of non-residential buildings	$	480,170,000			23	%	$	299,446,000			28.4	%
Schedule of Financing Receivables, Non Accrual Status [Table Text Block]		2014			2013
	Loans past due 90 days or more still accruing interest	$	0		$	0
	Nonaccrual loans		26,048,000			6,718,000
	Total nonperforming loans	$	26,048,000		$	6,718,000
		2014			2013
	Loans past due 90 days or more still accruing interest	$	26,000		$	NA
	Nonaccrual loans		3,358,000			NA
	Total nonperforming loans	$	3,384,000		$	NA
		December 31,			December 31,
		2014			2013
	Commercial:
	Commercial and industrial	$	6,478,000		$	1,501,000
	Vacant land, land development, and residential construction		209,000			785,000
	Real estate – owner occupied		18,062,000			389,000
	Real estate – non-owner occupied		378,000			168,000
	Real estate – multi-family and residential rental		106,000			208,000
	Total commercial		25,233,000			3,051,000
	Retail:
	Home equity and other		800,000			788,000
	1-4 family mortgages		3,399,000			2,879,000
	Total retail		4,199,000			3,667,000
	Total nonperforming loans	$	29,432,000		$	6,718,000
Past Due Financing Receivables [Table Text Block]								Greater											Recorded
		30 – 59			60 – 89			Than 89											Balance > 89
		Days			Days			Days			Total						Total		Days and
		Past Due			Past Due			Past Due			Past Due			Current			Loans		Accruing
	Originated Loans
	Commercial:
	Commercial and industrial	$	0		$	0		$	0		$	0		$	384,570,000		$	384,570,000	$	0
	Vacant land, land development, and residential construction		0			0			0			0			29,826,000			29,826,000		0
	Real estate – owner occupied		0			0			120,000			120,000			291,638,000			291,758,000		0
	Real estate – non-owner occupied		0			0			116,000			116,000			410,861,000			410,977,000		0
	Real estate – multi-family and residential rental		0			0			0			0			36,058,000			36,058,000		0
	Total commercial		0			0			236,000			236,000			1,152,953,000			1,153,189,000		0
	Retail:
	Home equity and other		38,000			3,000			0			41,000			50,018,000			50,059,000		0
	1- 4 family mortgages		0			0			366,000			366,000			42,502,000			42,868,000		0
	Total retail		38,000			3,000			366,000			407,000			92,520,000			92,927,000		0
	Total past due loans	$	38,000		$	3,000		$	602,000		$	643,000		$	1,245,473,000		$	1,246,116,000	$	0
								Greater											Recorded
		30 – 59			60 – 89			Than 89											Balance > 89
		Days			Days			Days			Total						Total		Days and
		Past Due			Past Due			Past Due			Past Due			Current			Loans		Accruing
	Acquired Loans
	Commercial:
	Commercial and industrial	$	29,000		$	32,000		$	76,000		$	137,000		$	165,900,000		$	166,037,000	$	0
	Vacant land, land development, and residential construction		0			38,000			0			38,000			22,110,000			22,148,000		0
	Real estate – owner occupied		51,000			425,000			1,625,000			2,101,000			136,529,000			138,630,000		0
	Real estate – non-owner occupied		68,000			598,000			395,000			1,061,000			147,536,000			148,597,000		0
	Real estate – multi-family and residential rental		37,000			0			105,000			142,000			86,560,000			86,702,000		0
	Total commercial		185,000			1,093,000			2,201,000			3,479,000			558,635,000			562,114,000		0
	Retail:
	Home equity and other		445,000			419,000			155,000			1,019,000			108,200,000			109,219,000		26,000
	1- 4 family mortgages		1,087,000			408,000			750,000			2,245,000			169,583,000			171,828,000		0
	Total retail		1,532,000			827,000			905,000			3,264,000			277,783,000			281,047,000		26,000
	Total past due loans	$	1,717,000		$	1,920,000		$	3,106,000		$	6,743,000		$	836,418,000		$	843,161,000	$	26,000
								Greater											Recorded
		30 – 59			60 – 89			Than 89											Balance > 89
		Days			Days			Days			Total						Total		Days and
		Past Due			Past Due			Past Due			Past Due			Current			Loans		Accruing
	Originated Loans
	Commercial:
	Commercial and industrial	$	0		$	0		$	309,000		$	309,000		$	286,064,000		$	286,373,000	$	0
	Vacant land, land development, and residential construction		0			0			0			0			36,741,000			36,741,000		0
	Real estate – owner occupied		65,000			0			50,000			115,000			261,762,000			261,877,000		0
	Real estate – non-owner occupied		0			0			0			0			364,066,000			364,066,000		0
	Real estate – multi-family and residential rental		0			0			64,000			64,000			37,575,000			37,639,000		0
	Total commercial		65,000			0			423,000			488,000			986,208,000			986,696,000		0
	Retail:
	Home equity and other		14,000			0			0			14,000			35,066,000			35,080,000		0
	1- 4 family mortgages		21,000			44,000			375,000			440,000			31,027,000			31,467,000		0
	Total retail		35,000			44,000			375,000			454,000			66,093,000			66,547,000		0
	Total past due loans	$	100,000		$	44,000		$	798,000		$	942,000		$	1,052,301,000		$	1,053,243,000	$	0
Impaired Financing Receivables [Table Text Block]											Year-To-Date
		Unpaid									Average
		Contractual			Recorded						Recorded
		Principal			Principal			Related			Principal
		Balance			Balance			Allowance			Balance
	With no related allowance recorded:
	Commercial:
	Commercial and industrial	$	1,170,000		$	1,164,000					$	652,000
	Vacant land, land development and residential construction		540,000			209,000						227,000
	Real estate – owner occupied		3,609,000			1,901,000						4,365,000
	Real estate – non-owner occupied		1,210,000			1,210,000						971,000
	Real estate – multi-family and residential rental		375,000			317,000						64,000
	Total commercial		6,904,000			4,801,000						6,279,000
	Retail:
	Home equity and other		207,000			191,000						517,000
	1-4 family mortgages		1,144,000			560,000						585,000
	Total retail		1,351,000			751,000						1,102,000
	Total with no related allowance recorded	$	8,255,000		$	5,552,000			0		$	7,381,000
											Year-To-Date
		Unpaid									Average
		Contractual			Recorded						Recorded
		Principal			Principal			Related			Principal
		Balance			Balance			Allowance			Balance
	With an allowance recorded:
	Commercial:
	Commercial and industrial	$	5,299,000		$	5,226,000		$	1,578,000		$	2,759,000
	Vacant land, land development and residential construction		2,000,000			2,000,000			151,000			3,229,000
	Real estate – owner occupied		15,745,000			15,674,000			2,200,000			4,630,000
	Real estate – non-owner occupied		16,033,000			15,949,000			4,779,000			18,245,000
	Real estate – multi-family and residential rental		1,371,000			1,371,000			666,000			1,700,000
	Total commercial		40,448,000			40,220,000			9,374,000			30,563,000
	Retail:
	Home equity and other		115,000			84,000			84,000			128,000
	1-4 family mortgages		2,194,000			2,000,000			694,000			2,115,000
	Total retail		2,309,000			2,084,000			778,000			2,243,000
	Total with an allowance recorded	$	42,757,000		$	42,304,000		$	10,152,000		$	32,806,000
	Total impaired loans:
	Commercial	$	47,352,000		$	45,021,000		$	9,374,000		$	36,842,000
	Retail		3,660,000			2,835,000			778,000			3,345,000
	Total impaired loans	$	51,012,000		$	47,856,000		$	10,152,000		$	40,187,000
											Year-To-Date
		Unpaid									Average
		Contractual			Recorded						Recorded
		Principal			Principal			Related			Principal
		Balance			Balance			Allowance			Balance
	With no related allowance recorded:
	Commercial:
	Commercial and industrial	$	1,586,000		$	1,579,000					$	563,000
	Vacant land, land development and residential construction		0			0						0
	Real estate – owner occupied		113,000			113,000						52,000
	Real estate – non-owner occupied		326,000			326,000						260,000
	Real estate – multi-family and residential rental		487,000			487,000						166,000
	Total commercial		2,512,000			2,505,000						1,041,000
	Retail:
	Home equity and other		641,000			639,000						262,000
	1-4 family mortgages		866,000			866,000						458,000
	Total retail		1,507,000			1,505,000						720,000
	Total with no related allowance recorded	$	4,019,000		$	4,010,000			0		$	1,761,000
											Year-To-Date
		Unpaid									Average
		Contractual			Recorded						Recorded
		Principal			Principal			Related			Principal
		Balance			Balance			Allowance			Balance
	With an allowance recorded:
Commercial:
Commercial and industrial	$	0		$	0		$	0		$	0
Vacant land, land development and residential construction		0			0			0			0
Real estate – owner occupied		1,516,000			1,502,000			605,000			501,000
Real estate – non-owner occupied		0			0			0			0
Real estate – multi-family and residential rental		0			0			0			0
Total commercial		1,516,000			1,502,000			605,000			501,000
Retail:
Home equity and other		0			0			0			0
1-4 family mortgages		0			0			0			0
Total retail		0			0			0			0
Total with an allowance recorded	$	1,516,000		$	1,502,000		$	605,000		$	501,000
Total impaired loans:
Commercial	$	4,028,000		$	4,007,000		$	605,000		$	1,542,000
Retail		1,507,000			1,505,000			0			720,000
Total impaired loans	$	5,535,000		$	5,512,000		$	605,000		$	2,262,000
										Year-To-Date
	Unpaid									Average
	Contractual			Recorded						Recorded
	Principal			Principal			Related			Principal
	Balance			Balance			Allowance			Balance
With no related allowance recorded:
Commercial:
Commercial and industrial	$	2,229,000		$	511,000					$	1,205,000
Vacant land, land development and residential construction		475,000			362,000						991,000
Real estate – owner occupied		1,270,000			785,000						1,084,000
Real estate – non-owner occupied		895,000			733,000						4,049,000
Real estate – multi-family and residential rental		41,000			1,000						390,000
Total commercial		4,910,000			2,392,000						7,719,000
Retail:
Home equity and other		507,000			461,000						471,000
1-4 family mortgages		1,272,000			647,000						727,000
Total retail		1,779,000			1,108,000						1,198,000
Total with no related allowance recorded	$	6,689,000		$	3,500,000			0		$	8,917,000
										Year-To-Date
	Unpaid									Average
	Contractual			Recorded						Recorded
	Principal			Principal			Related			Principal
	Balance			Balance			Allowance			Balance
With an allowance recorded:
Commercial:
Commercial and industrial	$	1,517,000		$	1,440,000		$	792,000		$	1,880,000
Vacant land, land development and residential construction		4,436,000			4,139,000			844,000			3,354,000
Real estate – owner occupied		1,513,000			1,513,000			528,000			2,550,000
Real estate – non-owner occupied		21,088,000			21,072,000			7,969,000			28,388,000
Real estate – multi-family and residential rental		3,219,000			2,684,000			1,127,000			2,915,000
Total commercial		31,773,000			30,848,000			11,260,000			39,087,000
Retail:
Home equity and other		320,000			289,000			96,000			329,000
1-4 family mortgages		2,274,000			2,231,000			1,030,000			1,628,000
Total retail		2,594,000			2,520,000			1,126,000			1,957,000
Total with an allowance recorded	$	34,367,000		$	33,368,000		$	12,386,000		$	41,044,000
Total impaired loans:
Commercial	$	36,683,000		$	33,240,000		$	11,260,000		$	46,806,000
Retail		4,373,000			3,628,000			1,126,000			3,155,000
Total impaired loans	$	41,056,000		$	36,868,000		$	12,386,000		$	49,961,000
Financing Receivable Credit Quality Indicators [Table Text Block]		Commercial			Commercial			Commercial			Commercial			Commercial
		and			Vacant Land, Land			Real Estate -			Real Estate -			Real Estate -
		Industrial			Development,			Owner			Non-Owner			Multi-Family
					and Residential			Occupied			Occupied			and Residential
					Construction									Rental
	Internal credit risk grade groupings:
	Grades 1 – 4	$	266,631,000		$	11,242,000		$	190,656,000		$	285,035,000		$	12,394,000
	Grades 5 – 7		109,639,000			16,375,000			83,123,000			113,982,000			22,282,000
	Grades 8 – 9		8,300,000			2,209,000			17,979,000			11,960,000			1,382,000
	Total commercial	$	384,570,000		$	29,826,000		$	291,758,000		$	410,977,000		$	36,058,000
					Commercial									Commercial
					Vacant Land,			Commercial			Commercial			Real Estate -
		Commercial			Land Development,			Real Estate -			Real Estate -			Multi-Family
		and			and Residential			Owner			Non-Owner			and Residential
		Industrial			Construction			Occupied			Occupied			Rental
	Internal credit risk grade groupings:
	Grades 1 – 4	$	72,411,000		$	5,875,000		$	39,496,000		$	65,886,000		$	35,858,000
	Grades 5 – 7		90,320,000			14,472,000			92,212,000			78,103,000			49,781,000
	Grades 8 – 9		3,306,000			1,801,000			6,922,000			4,608,000			1,063,000
	Total commercial	$	166,037,000		$	22,148,000		$	138,630,000		$	148,597,000		$	86,702,000
					Commercial Vacant Land, Land			Commercial			Commercial			Commercial Real Estate -
		Commercial			Development,			Real Estate -			Real Estate -			Multi-Family
		and			and Residential			Owner			Non-Owner			and Residential
		Industrial			Construction			Occupied			Occupied			Rental
	Internal credit risk grade groupings:
	Grades 1 – 4	$	208,151,000		$	6,973,000		$	156,230,000		$	219,325,000		$	15,465,000
	Grades 5 – 7		76,237,000			25,535,000			103,066,000			122,717,000			19,469,000
	Grades 8 – 9		1,985,000			4,233,000			2,581,000			22,024,000			2,705,000
	Total commercial	$	286,373,000		$	36,741,000		$	261,877,000		$	364,066,000		$	37,639,000
Allowance for Credit Losses on Financing Receivables [Table Text Block]		Commercial			Retail
		Loans			Loans			Unallocated			Total
	Allowance for loan losses:
	Beginning balance	$	20,455,000		$	2,358,000		$	8,000		$	22,821,000
	Provision for loan losses		(3,140,000	)		(721,000	)		68,000			(3,793,000	)
	Charge-offs		(876,000	)		(554,000	)		0			(1,430,000	)
	Recoveries		1,297,000			404,000			0			1,701,000
	Ending balance	$	17,736,000		$	1,487,000		$	76,000		$	19,299,000
	Ending balance: individually evaluated for impairment	$	9,374,000		$	777,000		$	0		$	10,151,000
	Ending balance: collectively evaluated for impairment	$	8,362,000		$	710,000		$	76,000		$	9,148,000
	Total loans:
	Ending balance	$	1,153,189,000		$	92,927,000					$	1,246,116,000
	Ending balance: individually evaluated for impairment	$	45,021,000		$	2,835,000					$	47,856,000
	Ending balance: collectively evaluated for impairment	$	1,108,168,000		$	90,092,000					$	1,198,260,000
		Commercial			Retail
		Loans			Loans			Unallocated			Total
	Allowance for loan losses:
	Beginning balance	$	0		$	0		$	0		$	0
	Provision for loan losses		734,000			59,000			0			793,000
	Charge-offs		(55,000	)		(16,000	)		0			(71,000	)
	Recoveries		2,000			18,000			0			20,000
	Ending balance	$	681,000		$	61,000		$	0		$	742,000
		Commercial			Retail
		Loans			Loans			Unallocated			Total
	Allowance for loan losses:
	Beginning balance	$	26,043,000		$	2,645,000		$	(11,000	)	$	28,677,000
	Provision for loan losses		(6,730,000	)		(489,000	)		19,000			(7,200,000	)
	Charge-offs		(5,120,000	)		(170,000	)		0			(5,290,000	)
	Recoveries		6,262,000			372,000			0			6,634,000
	Ending balance	$	20,455,000		$	2,358,000		$	8,000		$	22,821,000
	Ending balance: individually evaluated for impairment	$	11,260,000		$	1,126,000		$	0		$	12,386,000
	Ending balance: collectively evaluated for impairment	$	9,195,000		$	1,232,000		$	8,000		$	10,435,000
	Total loans:
	Ending balance	$	986,696,000		$	66,547,000					$	1,053,243,000
	Ending balance: individually evaluated for impairment	$	33,240,000		$	3,628,000					$	36,868,000
	Ending balance: collectively evaluated for impairment	$	953,456,000		$	62,919,000					$	1,016,375,000
		Commercial			Retail
		Loans			Loans			Unallocated			Total
	Allowance for loan losses:
	Beginning balance	$	33,431,000		$	3,019,000		$	82,000		$	36,532,000
	Provision for loan losses		(2,800,000	)		(207,000	)		(93,000	)		(3,100,000	)
	Charge-offs		(12,075,000	)		(569,000	)		0			(12,644,000	)
	Recoveries		7,487,000			402,000			0			7,889,000
	Ending balance	$	26,043,000		$	2,645,000		$	(11,000	)	$	28,677,000
	Ending balance: individually evaluated for impairment	$	16,860,000		$	329,000		$	0		$	17,189,000
	Ending balance: collectively evaluated for impairment	$	9,183,000		$	2,316,000		$	(11,000	)	$	11,488,000
	Total loans:
	Ending balance	$	968,506,000		$	72,683,000					$	1,041,189,000
	Ending balance: individually evaluated for impairment	$	55,138,000		$	2,141,000					$	57,279,000
	Ending balance: collectively evaluated for impairment	$	913,368,000		$	70,542,000					$	983,910,000
Troubled Debt Restructurings on Financing Receivables [Table Text Block]					Pre-			Post-
					Modification			Modification
					Recorded			Recorded
		Number of			Principal			Principal
		Contracts			Balance			Balance
	Originated Loans
	Commercial:
	Commercial and industrial		2		$	5,994,000		$	6,094,000
	Vacant land, land development and residential construction		0			0			0
	Real estate – owner occupied		2			16,787,000			16,787,000
	Real estate – non-owner occupied		1			146,000			146,000
	Real estate – multi-family and residential rental		0			0			0
	Total commercial		5			22,927,000			23,027,000
	Retail:
	Home equity and other		0			0			0
	1-4 family mortgages		0			0			0
	Total retail		0			0			0
	Total		5		$	22,927,000		$	23,027,000
	Acquired Loans
	Commercial:
	Commercial and industrial		7		$	1,604,000		$	1,604,000
	Vacant land, land development and residential construction		0			0			0
	Real estate – owner occupied		2			1,619,000			1,619,000
	Real estate – non-owner occupied		1			65,000			65,000
	Real estate – multi-family and residential rental		4			394,000			394,000
	Total commercial		14			3,682,000			3,682,000
	Retail:
	Home equity and other		1			26,000			26,000
	1-4 family mortgages		1			179,000			179,000
	Total retail		2			205,000			205,000
	Total		16		$	3,887,000		$	3,887,000
					Pre-			Post-
					Modification			Modification
					Recorded			Recorded
		Number of			Principal			Principal
		Contracts			Balance			Balance
	Commercial:
	Commercial and industrial		3		$	741,000		$	741,000
	Vacant land, land development and residential construction		2			3,610,000			3,610,000
	Real estate – owner occupied		2			715,000			715,000
	Real estate – non-owner occupied		1			45,000			45,000
	Real estate – multi-family and residential rental		1			241,000			241,000
	Total commercial		9			5,352,000			5,352,000
	Retail:
	Home equity and other		0			0			0
	1-4 family mortgages		1			1,879,000			1,879,000
	Total retail		1			1,879,000			1,879,000
	Total		10		$	7,231,000		$	7,231,000
Troubled Debt Restructurings on Financing Receivables WithIn Previous Twelve Months that Became Over Thirty Days Past Due [Table Text Block]					Recorded
		Number of			Principal
		Contracts			Balance
	Commercial:
	Commercial and industrial		0		$	0
	Vacant land, land development and residential construction		0			0
	Real estate – owner occupied		0			0
	Real estate – non-owner occupied		0			0
	Real estate – multi-family and residential rental		0			0
	Total commercial		0			0
	Retail:
	Home equity and other		0			0
	1-4 family mortgages		0			0
	Total retail		0			0
	Total		0		$	0
					Recorded
		Number of			Principal
		Contracts			Balance
	Commercial:
	Commercial and industrial		0		$	0
	Vacant land, land development and residential construction		0			0
	Real estate – owner occupied		0			0
	Real estate – non-owner occupied		0			0
	Real estate – multi-family and residential rental		0			0
	Total commercial		0			0
	Retail:
	Home equity and other		0			0
	1-4 family mortgages		0			0
	Total retail		0			0
	Total		0		$	0
		Number of			Principal
		Contracts			Balance
	Commercial:
	Commercial and industrial		0		$	0
	Vacant land, land development and residential construction		0			0
	Real estate – owner occupied		1			65,000
	Real estate – non-owner occupied		0			0
	Real estate – multi-family and residential rental		0			0
	Total commercial		1			65,000
	Retail:
	Home equity and other		0			0
	1-4 family mortgages		0			0
	Total retail		0			0
	Total		1		$	65,000
Trouble Debt Restructuring Activity [Table Text Block]					Commercial
					Vacant Land,			Commercial			Commercial			Commercial
					Land									Real Estate -
		Commercial			Development,			Real Estate -			Real Estate -			Multi-Family
		and			and Residential			Owner			Non-Owner			and Residential
		Industrial			Construction			Occupied			Occupied			Rental
	Commercial Loan Portfolio:
	Beginning Balance	$	1,656,000		$	4,501,000		$	1,816,000		$	22,311,000		$	2,620,000
	Charge-Offs		(67,000	)		0			(11,000	)		0			(420,000	)
	Payments		(871,000	)		(4,719,000	)		(2,343,000	)		(5,190,000	)		(1,695,000	)
	Transfers to ORE		(21,000	)		0			(48,000	)		0			0
	Net Additions/Deletions		6,329,000			2,898,000			17,746,000			318,000			0
	Ending Balance	$	7,026,000		$	2,680,000		$	17,160,000		$	17,439,000		$	505,000
		Retail			Retail
		Home Equity			1-4 Family
		and Other			Mortgages
	Retail Loan Portfolio:
	Beginning Balance	$	0		$	1,987,000
	Charge-Offs		0			0
	Payments		0			(224,000	)
	Transfers to ORE		0			0
	Net Additions/Deletions		0			204,000
	Ending Balance	$	0		$	1,967,000
					Commercial
					Vacant Land,			Commercial			Commercial			Commercial
					Land									Real Estate -
		Commercial			Development,			Real Estate -			Real Estate -			Multi-Family
		and			and Residential			Owner			Non-Owner			and Residential
		Industrial			Construction			Occupied			Occupied			Rental
	Commercial Loan Portfolio:
	Beginning Balance	$	0		$	0		$	0		$	0		$	0
	Charge-Offs		0			0			0			0			0
	Payments		(2,000	)		0			0			0			(18,000	)
	Transfers to ORE		0			0			0			0			0
	Net Additions/Deletions		1,441,000			0			1,569,000			64,000			399,000
	Ending Balance	$	1,439,000		$	0		$	1,569,000		$	64,000		$	381,000
		Retail			Retail
		Home Equity			1-4 Family
		and Other			Mortgages
	Retail Loan Portfolio:
	Beginning Balance	$	0		$	0
	Charge-Offs		0			0
	Payments		0			0
	Transfers to ORE		0			0
	Net Additions/Deletions		26,000			178,000
	Ending Balance	$	26,000		$	178,000
					Commercial
					Vacant Land,			Commercial			Commercial			Commercial
					Land									Real Estate -
		Commercial			Development,			Real Estate -			Real Estate -			Multi-Family
		and			and Residential			Owner			Non-Owner			and Residential
		Industrial			Construction			Occupied			Occupied			Rental
	Commercial Loan Portfolio:
	Beginning Balance	$	2,720,000		$	3,071,000		$	4,116,000		$	37,671,000		$	3,027,000
	Charge-Offs		(35,000	)		(725,000	)		(70,000	)		(2,537,000	)		(15,000	)
	Payments		(2,781,000	)		(1,596,000	)		(2,151,000	)		(13,795,000	)		(735,000	)
	Transfers to ORE		(74,000	)		0			(363,000	)		(1,153,000	)		0
	Net Additions/Deletions		1,826,000			3,751,000			284,000			2,126,000			343,000
	Ending Balance	$	1,656,000		$	4,501,000		$	1,816,000		$	22,312,000		$	2,620,000
		Retail			Retail
		Home Equity			1-4 Family
		and Other			Mortgages
	Retail Loan Portfolio:
	Beginning Balance	$	0		$	155,000
Charge-Offs		0			0
Payments		0			(46,000	)
Transfers to ORE		0			0
Net Additions/Deletions		0			1,878,000
Ending Balance	$	0		$	1,987,000
				Commercial
				Vacant Land,			Commercial			Commercial			Commercial
				Land									Real Estate -
	Commercial			Development,			Real Estate -			Real Estate -			Multi-Family
	and			and Residential			Owner			Non-Owner			and Residential
	Industrial			Construction			Occupied			Occupied			Rental
Commercial Loan Portfolio:
Beginning Balance	$	4,553,000		$	5,100,000		$	6,183,000		$	12,036,000		$	12,626,000
Charge-Offs		(540,000	)		(63,000	)		(426,000	)		(720,000	)		(2,180,000	)
Payments		(2,584,000	)		(2,013,000	)		(3,443,000	)		(2,482,000	)		(7,422,000	)
Transfers to ORE		(96,000	)		0			(65,000	)		(1,045,000	)		(186,000	)
Net Additions/Deletions		1,387,000			47,000			1,867,000			29,882,000			189,000
Ending Balance	$	2,720,000		$	3,071,000		$	4,116,000		$	37,671,000		$	3,027,000
	Retail			Retail
	Home Equity			1-4 Family
	and Other			Mortgages
Retail Loan Portfolio:
Beginning Balance	$	0		$	164,000
Charge-Offs		0			0
Payments		0			(9,000	)
Transfers to ORE		0			0
Net Additions/Deletions		0			0
Ending Balance	$	0		$	155,000
Allowance Related to Loans Categorized as Troubled Debt Restructurings [Table Text Block]		December 31,			December 31,
		2014			2013
	Commercial:
	Commercial and industrial	$	16,000		$	187,000
	Vacant land, land development, and residential construction		151,000			798,000
	Real estate – owner occupied		182,000			528,000
	Real estate – non-owner occupied		4,778,000			7,828,000
	Real estate – multi-family and residential rental		666,000			1,010,000
	Total commercial		5,793,000			10,351,000
	Retail:
	Home equity and other		0			0
	1-4 family mortgages		0			48,000
	Total retail		0			48,000
	Total related allowance	$	5,793,000		$	10,399,000
Retail Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Tables) [Line Items]
Financing Receivable Credit Quality Indicators [Table Text Block]		Retail			Retail
		Home Equity			1-4 Family
		and Other			Mortgages
	Total retail	$	50,059,000		$	42,868,000
		Retail			Retail
		Home Equity			1-4 Family
		and Other			Mortgages
	Total retail	$	109,219,000		$	171,828,000
		Retail			Retail
		Home Equity			1-4 Family
		and Other			Mortgages
	Total retail	$	35,080,000		$	31,467,000

Note_5_Premises_and_Equipment_1

Note 5 - Premises and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Table Text Block]		2014		2013
	Land and improvements	$	16,579,000	$	8,556,000
	Buildings		38,761,000		24,733,000
	Furniture and equipment		16,622,000		12,718,000
			71,962,000		46,007,000
	Less: accumulated depreciation		23,150,000		21,109,000
	Total premises and equipment	$	48,812,000	$	24,898,000

Note_6_Mortgage_Loan_Servicing1

Note 6 - Mortgage Loan Servicing (Tables)	12 Months Ended
	Dec. 31, 2014
Mortgage Loan Servicing [Abstract]
Mortgage Loans Serviced for Others [Table Text Block]		2014
	Mortgage loan portfolios serviced for:
	Federal Home Loan Mortgage Corporation	$	589,118,000
	Federal Home Loan Bank		1,702,000
	Total mortgage loans serviced for others	$	590,820,000
Schedule of Servicing Assets at Fair Value [Table Text Block]		2014
	Balance at January 1, 2014	$	0
	Firstbank merger		7,389,000
	Additions		575,000
	Amortized to expense		(1,252,000	)
	Balance at December 31, 2014	$	6,712,000
Servicing Asset at Amortized Cost [Table Text Block]	2015	$	1,560,000
	2016		1,256,000
	2017		1,023,000
	2018		857,000
	2019		722,000
	Thereafter		1,294,000

Note_7_Core_Deposit_Intangible1

Note 7 - Core Deposit Intangible Assets, Net (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	2015	$	2,992,000
	2016		2,675,000
	2017		2,357,000
	2018		2,039,000
	2019		1,721,000
	Thereafter		3,839,000

Note_8_Deposits_Tables

Note 8 - Deposits (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Summary of Deposits and Percentage Change in Deposits [Table Text Block]												Percent
		31-Dec-14					31-Dec-13					Increase
		Balance		%			Balance		%			(Decrease)
	Noninterest-bearing demand	$	558,738,000		24.5	%	$	224,580,000		20.1	%		148.8	%
	Interest-bearing checking		413,382,000		18.2			197,388,000		17.6			109.4
	Money market		235,587,000		10.3			133,369,000		11.9			76.6
	Savings		330,459,000		14.5			52,606,000		4.7			528.2
	Time, under $100,000		181,026,000		8			43,251,000		3.9			318.5
	Time, $100,000 and over		382,120,000		16.8			254,600,000		22.8			50.1
			2,101,312,000		92.3			905,794,000		81			132
	Out-of-area time, under $100,000		2,422,000		0.1			4,078,000		0.4			(40.6	)
	Out-of-area time, $100,000 and over		173,181,000		7.6			209,039,000		18.6			(17.2	)
			175,603,000		7.7			213,117,000		19			(17.6	)
	Total deposits	$	2,276,915,000		100	%	$	1,118,911,000		100	%		103.5
ContractualMaturities of Certificates of Deposits [Table Text Block]		2014		2013
	In one year or less	$	368,163,000	$	213,454,000
	In one to two years		153,346,000		80,138,000
	In two to three years		118,919,000		73,271,000
	In three to four years		60,953,000		95,979,000
	In four to five years		37,368,000		48,126,000
	Total certificates of deposit	$	738,749,000	$	510,968,000
Contractual Maturities of Certificates of Deposits of More Than Specified Amount [Table Text Block]		2014		2013
	Up to three months	$	75,356,000	$	57,469,000
	Three months to six months		65,838,000		41,237,000
	Six months to twelve months		125,492,000		93,920,000
	Over twelve months		288,615,000		271,013,000
	Total certificates of deposit	$	555,301,000	$	463,639,000

Note_9_Securities_Sold_Under_A1

Note 9 - Securities Sold Under Agreements to Repurchase (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Schedule of Repurchase Agreements [Table Text Block]		2014			2013
	Outstanding balance at year-end	$	167,569,000		$	69,305,000
	Weighted average interest rate at year-end		0.11	%		0.12	%
	Average daily balance during the year	$	105,474,000		$	65,939,000
	Weighted average interest rate during the year		0.12	%		0.12	%
	Maximum daily balance during the year	$	178,042,000		$	78,960,000

Note_10_Federal_Home_Loan_Bank1

Note 10 - Federal Home Loan Bank Advances (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Maturities of Currently Outstanding FHLB Advances [Table Text Block]	Maturities over the next five years are:
	2015	$	6,022,000
	2016		3,000,000
	2017		45,000,000
	2018		0
	2019		0

Note_11_Federal_Income_Taxes_T

Note 11 - Federal Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]		2014			2013			2012
	Current expense	$	3,359,000		$	0		$	0
	Deferred expense		4,506,000			8,092,000			5,636,000
	Tax expense	$	7,865,000		$	8,092,000		$	5,636,000
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]		2014			2013			2012
	Tax at statutory rate (35%)	$	8,819,000		$	8,794,000		$	6,360,000
	Increase (decrease) from
	Tax-exempt interest		(621,000	)		(347,000	)		(486,000	)
	Bank owned life insurance		(415,000	)		(465,000	)		(535,000	)
	Other		82,000			110,000			297,000
	Tax expense	$	7,865,000		$	8,092,000		$	5,636,000
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]		2014			2013
	Deferred income tax assets
	Allowance for loan losses	$	7,014,000		$	7,987,000
	Tax credit carryforwards		3,395,000			1,397,000
	Nonaccrual loan interest income		471,000			605,000
	Deferred compensation		1,304,000			567,000
	Deferred loan fees		445,000			273,000
	Fair value write-downs on foreclosed properties		212,000			241,000
	Fair value of interest rate swap		89,000			92,000
	Losses on capital investments		450,000			0
	Stock compensation		521,000			207,000
	Net operating loss carryforward		0			4,050,000
	Unrealized loss on securities		0			2,908,000
	Other		725,000			136,000
			14,626,000			18,463,000
	Deferred income tax liabilities
	Depreciation		1,217,000			419,000
	Prepaid expenses		425,000			192,000
	Core deposit intangible		5,386,000			0
	Mortgage loan servicing rights		2,349,000			0
	Unrealized gain on securities		112,000			0
	Other		476,000			98,000
			9,965,000			709,000
	Net deferred tax asset before valuation allowance		4,661,000			17,754,000
	Valuation allowance		(450,000	)		0
	Total net deferred tax asset	$	4,211,000		$	17,754,000

Note_12_Stockbased_Compensatio1

Note 12 - Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Note 12 - Stock-based Compensation (Tables) [Line Items]
Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]			2014							2013					2012
							Weighted						Weighted					Weighted
							Average						Average					Average
			Shares				Fair Value			Shares			Fair Value		Shares			Fair Value
	Nonvested at beginning of year			63,800			$	14.3			66,100		$	14.3		38,650		$	6.2
	Granted			101,490				20.13			0		NA			66,100			14.3
	Vested			(63,300	)			14.3			0		NA			(38,266	)		6.2
	Forfeited			(500	)			14.3			(2,300	)		14.3		(384	)		6.2
	Nonvested at end of year			101,490			$	20.13			63,800		$	14.3		66,100		$	14.3
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]			2014							2013					2012
							Weighted						Weighted					Weighted
							Average						Average					Average
							Exercise						Exercise					Exercise
			Shares				Price			Shares			Price		Shares			Price
	Outstanding at beginning of year			60,876			$	33.11			152,896		$	26.15		214,903		$	22.4
	Granted			6,488				22.15			0		NA			0		NA
	Exercised			(2,845	)			17.74			(51,055	)		13.72		(50,930	)		10.83
	Forfeited or expired			(29,184	)			34.6			(40,965	)		31.3		(11,077	)		23.77
	Outstanding at end of year			35,335			$	31.09			60,876		$	33.11		152,896		$	26.15
	Options exercisable at year-end			28,847			$	33.11			60,876		$	33.11		152,896		$	26.15
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]			2014
	Risk-free interest rate			1.56	%
	Expected option life (Years)			5
	Expected stock price volatility			26	%
	Dividend yield			2.5	%
Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]						Outstanding							Exercisable
									Weighted Average	Weighted					Weighted
	Range of								Remaining	Average					Average
	Exercise								Contractual	Exercise					Exercise
	Prices					Number			Life (Years)	Price			Number		Price
	$6.21	-	$8.00				2,700		0.9	$	6.21			2,700	$	6.21
	$20.01	-	$24.00				6,488		6.9		22.15			0	NA
	$32.01	-	$36.00				26,147		0.9		35.88			26,147		35.88
	Outstanding at year end						35,335		2	$	31.09			28,847	$	33.11
						Outstanding							Exercisable
									Weighted Average	Weighted					Weighted
	Range of								Remaining	Average					Average
	Exercise								Contractual	Exercise					Exercise
	Prices					Number			Life (Years)	Price			Number		Price
	$4.00	-	$8.00				63,590		4.9	$	6.53			56,385	$	6.7
	$8.01	-	$12.00				68,430		3.7		13.2			68,430		13.2
	$20.01	-	$25.00				85,962		1.4		22.43			85,962		22.43
	Outstanding at year end						217,982		3.1	$	14.89			210,777	$	15.22
Schedule of Share-based Compensation Shares Authorized under Stock Option Plans Information Related to Option Outstanding [Table Text Block]			2014				2013			2012
	Minimum exercise price		$	6.21			$	6.21		$	6.21
	Maximum exercise price			35.88				40.28			40.28
	Average remaining option term (Years)		2				1.4			1.9
			2014
	Minimum exercise price		$	5.19
	Maximum exercise price			24.46
	Average remaining option term (Years)		3.1
Schedule of Share-based Compensation Arrangement by Share-based Payment Award Options Information Related to Stock Option Grants and Exercised [Table Text Block]			2014				2013			2012
	Aggregate intrinsic value of stock options exercised		$	11,000			$	408,000		$	307,000
	Cash received from stock option exercises			50,000				289,000			227,000
	Tax benefit realized from stock option exercises			0				0			0
	Weighted average per share fair value of stock options granted		$	2.72				NA			NA
			2014
	Aggregate intrinsic value of stock options exercised		$	333,000
	Cash received from stock option exercises			232,000
	Tax benefit realized from stock option exercises			116,000
	Weighted average per share fair value of stock options granted		NA
Firstbank Plans [Member]
Note 12 - Stock-based Compensation (Tables) [Line Items]
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]			2014
							Weighted
							Average
							Exercise
			Shares				Price
	Outstanding at beginning of year			0				0
	Granted			0				0
	Replaced as part of merger			282,178				15.48
	Exercised			(27,740	)			8.34
	Forfeited or expired			(36,456	)			24.46
	Outstanding at end of year			217,982			$	14.89
	Options exercisable at year-end			210,777			$	15.22

Note_13_Related_Parties_Tables

Note 13 - Related Parties (Tables)	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Schedule of Related Party Transactions [Table Text Block]		2014			2013
	Beginning balance	$	6,884,000		$	1,418,000
	New loans		781,000			6,309,000
	Repayments		(381,000	)		(252,000	)
	Adjustments		1,718,000			(591,000	)
	Ending balance	$	9,002,000		$	6,884,000

Note_14_Commitments_and_Offbal1

Note 14 - Commitments and Off-balance-sheet Risk (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block Supplement [Abstract]
Summary of Contractual Amounts of Financial Instruments with Off-balance Sheet Risk [Table Text Block]		2014		2013
	Commercial unused lines of credit	$	554,856,000	$	257,937,000
	Unused lines of credit secured by 1 – 4 family residential properties		60,983,000		23,429,000
	Credit card unused lines of credit		11,649,000		9,013,000
	Other consumer unused lines of credit		8,673,000		5,695,000
	Commitments to make loans		110,126,000		58,799,000
	Standby letters of credit		35,461,000		19,670,000
	Total commitments	$	781,748,000	$	374,543,000
Schedule of Fair Value, Off-balance Sheet Risks [Table Text Block]		2014				2013
		Contract		Carrying		Contract		Carrying
		Amount		Value		Amount		Value
	Standby letters of credit	$	35,461,000	$	150,000	$	19,670,000	$	148,000

Note_17_Fair_Values_of_Financi1

Note 17 - Fair Values of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value, by Balance Sheet Grouping [Table Text Block]		Level in		2014				2013
		Fair Value		Carrying		Fair		Carrying		Fair
		Hierarchy		Amount		Value		Amount		Value
	Financial assets
	Cash	Level 1		$	13,261	$	13,261	$	1,464	$	1,464
	Cash equivalents	Level 2			159,477		159,477		145,501		145,501
	Securities available for sale		-1		432,912		432,912		131,178		131,178
	Federal Home Loan Bank stock		-2		13,699		13,699		11,961		11,961
	Loans, net	Level 3			2,069,236		2,064,140		1,030,422		1,027,300
	Bank owned life insurance	Level 2			57,861		57,861		51,377		51,377
	Accrued interest receivable	Level 2			8,033		8,033		3,649		3,649
	Financial liabilities
	Deposits	Level 2			2,276,915		2,254,749		1,118,911		1,120,576
	Securities sold under agreements to repurchase	Level 2			167,569		167,569		69,305		69,305
	Federal Home Loan Bank advances	Level 2			54,022		54,720		45,000		45,139
	Subordinated debentures	Level 2			54,472		54,508		32,990		32,974
	Accrued interest payable	Level 2			1,942		1,942		2,041		2,041
	Interest rate swap		-1		253		253		264		264

Note_18_Fair_Values_Measuremen1

Note 18 - Fair Values Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]					Quoted Prices
					in Active		Significant
					Markets for		Other			Significant
					Identical		Observable			Unobservable
					Assets		Inputs			Inputs
		Total			(Level 1)		(Level 2)			(Level 3)
	Available for sale securities
	U.S. Government agency debt obligations	$	193,468,000		$	0	$	193,468,000		$	0
	Mortgage-backed securities		93,561,000			0		93,561,000			0
	Municipal general obligation bonds		133,082,000			0		122,801,000			10,281,000
	Municipal revenue bonds		10,873,000			0		10,873,000			0
	Other investments		1,928,000			0		1,928,000			0
	Derivatives
	Interest rate swap agreement		(253,000	)		0		(253,000	)		0
	Total	$	432,659,000		$	0	$	422,378,000		$	10,281,000
					Quoted Prices
					in Active		Significant
					Markets for		Other			Significant
					Identical		Observable			Unobservable
					Assets		Inputs			Inputs
		Total			(Level 1)		(Level 2)			(Level 3)
	Available for sale securities U.S. Government agency debt obligations	$	98,477,000		$	0	$	98,477,000		$	0
	Mortgage-backed securities		13,558,000			0		13,558,000			0
	Municipal general obligation bonds		16,872,000			0		16,872,000			0
	Municipal revenue bonds		916,000			0		916,000			0
	Mutual funds		1,355,000			0		1,355,000			0
	Derivatives
	Interest rate swap agreement		(264,000	)		0		(264,000	)		0
	Total	$	130,914,000		$	0	$	130,914,000		$	0
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Valuation Techniques [Table Text Block]					Quoted Prices
					in Active		Significant
					Markets for		Other			Significant
					Identical		Observable			Unobservable
					Assets		Inputs			Inputs
		Total			(Level 1)		(Level 2)			(Level 3)
	Impaired loans (1)	$	17,097,000		$	0	$	0		$	17,097,000
	Foreclosed assets (1)		1,995,000			0		0			1,995,000
	Total	$	19,092,000		$	0	$	0		$	19,092,000
					Quoted Prices
					in Active		Significant
					Markets for		Other			Significant
					Identical		Observable			Unobservable
					Assets		Inputs			Inputs
		Total			(Level 1)		(Level 2)			(Level 3)
	Impaired loans (1)	$	23,405,000		$	0	$	0		$	23,405,000
	Foreclosed assets (1)		2,851,000			0		0			2,851,000
	Total	$	26,256,000		$	0	$	0		$	26,256,000

Note_19_Earnings_Per_Share_Tab

Note 19 - Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]		2014		2013		2012
	Basic
	Net income attributable to common shares	$	17,331,000	$	17,033,000	$	11,505,000
	Weighted average common shares outstanding		13,510,991		8,710,677		8,625,198
	Basic earnings per common share	$	1.28	$	1.96	$	1.33
	Diluted
	Net income attributable to common shares	$	17,331,000	$	17,033,000	$	11,505,000
	Weighted average common shares outstanding for basic earnings per common share		13,510,991		8,710,677		8,625,198
	Add: Dilutive effects of share-based awards		30,913		14,031		224,429
	Average shares and dilutive potential common shares		13,541,904		8,724,708		8,849,627
	Diluted earnings per common share	$	1.28	$	1.95	$	1.3

Note_20_Subordinated_Debenture1

Note 20 - Subordinated Debentures (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Schedule of Subordinated Borrowing [Table Text Block]		Preferred
		Securities
	Trust Name	Outstanding	Interest Rate	Maturity Date
	Mercantile Bank Capital Trust I	$32,000,000	3 Month Libor + 218 bps	16-Sep-34
	Firstbank Capital Trust I	$10,000,000	3 Month Libor + 199 bps	18-Oct-34
	Firstbank Capital Trust II	$10,000,000	3 Month Libor + 127 bps	7-Apr-36
	Firstbank Capital Trust III	$7,500,000	3 Month Libor + 135 bps	30-Jul-37
	Firstbank Capital Trust IV	$7,500,000	3 Month Libor + 135 bps	30-Jul-37

Note_21_Regulatory_Matters_Tab

Note 21 - Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block]												Minimum Required
												to be Well
							Minimum Required					Capitalized Under
							for Capital					Prompt Corrective
		Actual					Adequacy Purposes					Action Regulations
		Amount		Ratio			Amount		Ratio			Amount		Ratio
	2014
	Total capital (to risk weighted assets)
	Consolidated	$	334,793		14.4	%	$	185,553		8	%	$	NA		NA
	Bank		332,749		14.4			185,309		8			231,636		10	%
	Tier 1 capital (to risk weighted assets)
	Consolidated		314,752		13.6			92,777		4			NA		NA
	Bank		312,708		13.5			92,655		4			138,982		6
	Tier 1 capital (to average assets)
	Consolidated		314,752		11.2			112,949		4			NA		NA
	Bank		312,708		11.1			112,856		4			141,070		5
	2013
	Total capital (to risk weighted assets)
	Consolidated	$	193,925		15.9	%	$	97,498		8	%	$	NA		NA
	Bank		190,493		15.7			97,329		8			121,662		10	%
	Tier 1 capital (to risk weighted assets)
	Consolidated		178,598		14.7			48,749		4			NA		NA
	Bank		175,192		14.4			48,665		4			72,997		6
	Tier 1 capital (to average assets)
	Consolidated		178,598		12.5			57,006		4			NA		NA
	Bank		175,192		12.3			56,860		4			71,075		5

Note_24_Quarterly_Financial_Da1

Note 24 - Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]		Interest		Net Interest		Net		Earnings per Share
		Income		Income		Income		Basic		Diluted
	2014
	First quarter	$	13,588,000	$	11,064,000	$	3,580,000	$	0.41	$	0.41
	Second quarter		18,483,000		15,552,000		1,510,000		0.13		0.13
	Third quarter		28,900,000		25,989,000		5,948,000		0.35		0.35
	Fourth quarter		28,147,000		25,173,000		6,293,000		0.37		0.37
	2013
	First quarter	$	14,210,000	$	11,455,000	$	4,401,000	$	0.51	$	0.5
	Second quarter		13,992,000		11,312,000		4,016,000		0.46		0.46
	Third quarter		14,667,000		11,994,000		3,453,000		0.4		0.4
	Fourth quarter		15,373,000		12,695,000		5,163,000		0.59		0.59

Note_25_Mercantile_Bank_Corpor1

Note 25 - Mercantile Bank Corporation (Parent Company Only) Condensed Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Balance Sheet [Table Text Block]		2014			2013
	ASSETS
	Cash and cash equivalents	$	1,441,000		$	2,506,000
	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
Condensed Income Statement [Table Text Block]		2014			2013			2012
	Income
	Interest and dividends from subsidiaries	$	12,139,000		$	5,516,000		$	32,532,000
	Total income		12,139,000			5,516,000			32,532,000
	Expenses
	Interest expense		2,145,000			1,213,000			884,000
	Other operating expenses		3,552,000			2,773,000			1,048,000
	Total expenses		5,697,000			3,986,000			1,932,000
	Income before income tax benefit and equity in undistributed net income (loss) of subsidiary		6,442,000			1,530,000			30,600,000
	Federal income tax benefit		(1,758,000	)		(1,042,000	)		(665,000	)
	Equity in undistributed net income (loss) of subsidiary		9,131,000			14,461,000			(18,730,000	)
	Net income		17,331,000			17,033,000			12,535,000
	Preferred stock dividends and accretion		0			0			1,030,000
	Net income attributable to common shares	$	17,331,000		$	17,033,000		$	11,505,000
	Comprehensive income	$	22,920,000		$	9,810,000		$	10,857,000
Condensed Cash Flow Statement [Table Text Block]		2014			2013			2012
	Cash flows from operating activities
	Net income	$	17,331,000		$	17,033,000		$	12,535,000
	Adjustments to reconcile net income to net cash from operating activities:
	Equity in undistributed (income) loss of subsidiary		(9,131,000	)		(14,461,000	)		18,730,000
	Stock-based compensation expense		714,000			473,000			54,000
	Change in other assets		(8,163,000	)		3,244,000			(3,006,000	)
	Change in other liabilities		21,979,000			(708,000	)		1,073,000
	Net cash from operating activities		22,730,000			5,581,000			29,386,000
	Cash flows from investing activities
	Net capital investment into subsidiaries		0			0			0
	Net cash for investing activities		0			0			0
	Cash flows from financing activities
	Repurchase of preferred stock		0			0			(21,000,000	)
	Repurchase of common stock warrant		0			0			(7,465,000	)
	Stock option exercises, net of cashless exercises		282,000			289,000			227,000
	Employee stock purchase plan		23,000			19,000			39,000
	Dividend reinvestment plan		209,000			33,000			14,000
	Stock grants to directors for retainer fees		155,000			0			0
	Cash dividends on preferred stock		0			0			(496,000	)
	Cash dividends on common stock		(24,464,000	)		(3,889,000	)		(774,000	)
	Net cash for financing activities		(23,795,000	)		(3,548,000	)		(29,455,000	)
	Net change in cash and cash equivalents		(1,065,000	)		2,033,000			(69,000	)
	Cash and cash equivalents at beginning of period		2,506,000			473,000			542,000
	Cash and cash equivalents at end of period	$	1,441,000		$	2,506,000		$	473,000

Note_1_Summary_of_Significant_2

Note 1 - Summary of Significant Accounting Policies (Details) (USD $)	0 Months Ended	12 Months Ended
	Jun. 01, 2014	Dec. 31, 2014	Dec. 31, 2013
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Entity Incorporation, Date of Incorporation		15-Jul-97
Entity Incorporation Date of Operations		15-Dec-97
Business Acquisition, Effective Date of Acquisition	1-Jun-14
Number of Operating Segments		1
Loans and Leases Receivable, Deferred Income		$1,100,000	$500,000
Interest Income on Commercial and Mortgage Loans, Discontinued Period		90 days
Maximum Delinquency Period for Consumer and Credit Card Loans to be Charged-off		120 days
Repossessed Assets		2,000,000	2,900,000
Building Improvements [Member] | Minimum [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life		5 years
Building Improvements [Member] | Maximum [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life		33 years
Furniture and Fixtures [Member] | Minimum [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life		3 years
Furniture and Fixtures [Member] | Maximum [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life		7 years
Core Deposits [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		10 years
Firstbank Corporation [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	1,452,880,000
Business Combination, Branches Acquired	46
Mercantile Real Estate [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Business Initiation Date of Company		21-Jul-03

Note_1_Summary_of_Significant_3

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

Note_2_Business_Combination_De

Note 2 - Business Combination (Details) (USD $)	12 Months Ended			0 Months Ended		6 Months Ended	24 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Jun. 01, 2014	Jun. 30, 2014	Dec. 31, 2014
Note 2 - Business Combination (Details) [Line Items]
Goodwill	$49,473,000	$0		$49,473,000			$49,473,000
Business Combination, Acquisition Related Costs	5,447,000	1,246,000	0
Firstbank Corporation [Member]
Note 2 - Business Combination (Details) [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets					1,452,880,000
Business Combination, Branches Acquired					46
Business Acquisition, Conversion of Stock Per Share (in Shares)					1
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in Shares)					8,087,272	8,087,272
Goodwill					49,473,000
Goodwill, Purchase Accounting Adjustments				-1,400,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment Net Deferred Tax Asset				1,400,000
Business Combination, Acquisition Related Costs	5,400,000	1,200,000
Business Combination, Aggregate Merger Related Expenses Recorded by Acquirer and Acquiree							12,200,000
Business Combination, Acquired Receivables and Certain Loans, Estimated Uncollectible Cash Flows					10,400,000
Business Combination, Acquired Receivables and Certain Loans, Pre-acquisition Charge-offs					2,800,000
Business Combination, Acquired Receivables and Certain Loans, Estimated Uncollectible Interest					3,900,000
Business Combination, Acquired Receivables, Gross Contractual Amount					926,400,000
Business Combination, Acquired Receivables, Unaccredted Discount					$8,100,000

Note_2_Business_Combination_De1

Note 2 - Business Combination (Details) - Purchase Price (Firstbank Corporation [Member], USD $)	0 Months Ended	6 Months Ended
	Jun. 01, 2014	Jun. 30, 2014
Firstbank Corporation [Member]
Purchase Price:
Mercantile common shares issued for Firstbank common shares (in Shares)	8,087,272	8,087,272
Price per share, based on Mercantile closing price on May 30, 2014 (in Dollars per share)		$21.43
Value of common stock issued		$173,310,000
Value of replacement stock options granted		1,664,000
Total purchase price		$174,974,000

Note_2_Business_Combination_De2

Note 2 - Business Combination (Details) - Net Assets Acquired (USD $)	Dec. 31, 2014	Dec. 31, 2013	Jun. 01, 2014
Liabilities
Goodwill	$49,473,000	$0
Core Deposits [Member] | Firstbank Corporation [Member]
Assets
Intangibles			17,478,000
Servicing Contracts [Member] | Firstbank Corporation [Member]
Assets
Intangibles			7,389,000
Firstbank Corporation [Member]
Assets
Cash and cash equivalents			91,806,000
Securities			358,599,000
Total loans			943,662,000
Premises and equipment			24,049,000
Other assets			9,897,000
Total Assets			1,452,880,000
Liabilities
Deposits			1,229,609,000
Borrowings			87,615,000
Other liabilities			10,155,000
Total Liabilities			1,327,379,000
Net Identifiable Assets Acquired			125,501,000
Goodwill			$49,473,000

Note_2_Business_Combination_De3

Note 2 - Business Combination (Details) - Pro Forma Information (Firstbank Corporation [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Firstbank Corporation [Member]
Note 2 - Business Combination (Details) - Pro Forma Information [Line Items]
Net interest income	$98,607,000	$93,862,000
Noninterest expense	81,295,000	93,263,000
Net income	$22,659,000	$16,068,000
Net income per diluted share (in Dollars per share)	$1.33	$0.96

Note_2_Business_Combination_De4

Note 2 - Business Combination (Details) - Acquired Loans Fair Value (Firstbank Corporation [Member], USD $)	Jun. 01, 2014
Commercial Loans:
Loans	$943,662,000
Commercial and Industrial [Member] | Nonperforming Financing Receivable [Member]
Commercial Loans:
Loans	878,000
Commercial and Industrial [Member] | Performing Financing Receivable [Member]
Commercial Loans:
Loans	163,316,000
Commercial and Industrial [Member]
Commercial Loans:
Loans	164,194,000
Commercial Real Estate Portfolio Segment [Member] | Nonperforming Financing Receivable [Member]
Commercial Loans:
Loans	12,973,000
Commercial Real Estate Portfolio Segment [Member] | Performing Financing Receivable [Member]
Commercial Loans:
Loans	378,016,000
Commercial Real Estate Portfolio Segment [Member]
Commercial Loans:
Loans	390,989,000
Commercial Real Estate Construction Financing Receivable [Member] | Nonperforming Financing Receivable [Member]
Commercial Loans:
Loans	1,289,000
Commercial Real Estate Construction Financing Receivable [Member] | Performing Financing Receivable [Member]
Commercial Loans:
Loans	33,726,000
Commercial Real Estate Construction Financing Receivable [Member]
Commercial Loans:
Loans	35,015,000
Commercial Portfolio Segment [Member] | Nonperforming Financing Receivable [Member]
Commercial Loans:
Loans	15,140,000
Commercial Portfolio Segment [Member] | Performing Financing Receivable [Member]
Commercial Loans:
Loans	575,058,000
Commercial Portfolio Segment [Member]
Commercial Loans:
Loans	590,198,000
Residential Portfolio Segment [Member] | Nonperforming Financing Receivable [Member]
Commercial Loans:
Loans	9,694,000
Residential Portfolio Segment [Member] | Performing Financing Receivable [Member]
Commercial Loans:
Loans	216,653,000
Residential Portfolio Segment [Member]
Commercial Loans:
Loans	226,347,000
Consumer Installment Portfolio Segment [Member] | Nonperforming Financing Receivable [Member]
Commercial Loans:
Loans	167,000
Consumer Installment Portfolio Segment [Member] | Performing Financing Receivable [Member]
Commercial Loans:
Loans	61,657,000
Consumer Installment Portfolio Segment [Member]
Commercial Loans:
Loans	61,824,000
Consumer Home Equity Line Portfolio Segment [Member] | Nonperforming Financing Receivable [Member]
Commercial Loans:
Loans	288,000
Consumer Home Equity Line Portfolio Segment [Member] | Performing Financing Receivable [Member]
Commercial Loans:
Loans	52,054,000
Consumer Home Equity Line Portfolio Segment [Member]
Commercial Loans:
Loans	52,342,000
Consumer Construction Portfolio Segment [Member] | Nonperforming Financing Receivable [Member]
Commercial Loans:
Loans	76,000
Consumer Construction Portfolio Segment [Member] | Performing Financing Receivable [Member]
Commercial Loans:
Loans	12,875,000
Consumer Construction Portfolio Segment [Member]
Commercial Loans:
Loans	12,951,000
Consumer Portfolio Segment [Member] | Nonperforming Financing Receivable [Member]
Commercial Loans:
Loans	10,225,000
Consumer Portfolio Segment [Member] | Performing Financing Receivable [Member]
Commercial Loans:
Loans	343,239,000
Consumer Portfolio Segment [Member]
Commercial Loans:
Loans	353,464,000
Nonperforming Financing Receivable [Member]
Commercial Loans:
Loans	25,365,000
Performing Financing Receivable [Member]
Commercial Loans:
Loans	$918,297,000

Note_2_Business_Combination_De5

Note 2 - Business Combination (Details) - Acquired Impaired and Non-impaired Loans (Firstbank Corporation [Member], USD $)	Jun. 01, 2014
Firstbank Corporation [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required payments	$44,936,000
Nonaccretable difference	17,057,000
Expected cash flows	27,879,000
Accretable yield	2,514,000
Carrying balance	$25,365,000

Note_3_Securities_Details

Note 3 - Securities (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2014
Note 3 - Securities (Details) [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$88,446,000		264,699,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	10,100,000		3,576,000
Available-for-sale Debt Securities, Amortized Cost Basis			432,591,000
Available-for-sale Securities	131,178,000	[1]	432,912,000	[1]
Debt Securities [Member]
Note 3 - Securities (Details) [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions			341
Michigan Strategic Fund Bonds [Member]
Note 3 - Securities (Details) [Line Items]
Available-for-sale Securities, Sold at Par	10,300,000
State of Michigan and all its Political Subdivisions [Member]
Note 3 - Securities (Details) [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	17,400,000		113,100,000
Available-for-sale Securities	17,800,000		113,900,000
All Other States and Their Political Subdivisions [Member]
Note 3 - Securities (Details) [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis			30,000,000
Available-for-sale Securities			30,000,000
Securities Other Than US Government Agencies and the State of Michigan and Political Subdivisions [Member] | Stockholders' Equity, Total [Member] | Securities Issued Concentration Risk [Member]
Note 3 - Securities (Details) [Line Items]
Concentration Risk, Percentage			10.00%
US Government Agency Debt Obligations and Mortgage-Backed Securities [Member]
Note 3 - Securities (Details) [Line Items]
Available-for-sale Securities, Restricted	$94,400,000		180,500,000
[1]	See Note 18 for a description of the fair value hierarchy as well as a disclosure of levels for classes of financial assets and liabilities.

Note_3_Securities_Details_Avai

Note 3 - Securities (Details) - Available-for-sale Securities (USD $)	Dec. 31, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	$432,591,000		$139,487,000
Securities available for sale, gross unrealized gains	3,897,000		1,791,000
Securities available for sale, gross unrealized losses	-3,576,000		-10,100,000
Securities available for sale	432,912,000	[1]	131,178,000	[1]
US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	194,894,000		108,279,000
Securities available for sale, gross unrealized gains	1,612,000		263,000
Securities available for sale, gross unrealized losses	-3,038,000		-10,065,000
Securities available for sale	193,468,000		98,477,000
Collateralized Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	92,656,000		12,456,000
Securities available for sale, gross unrealized gains	1,123,000		1,102,000
Securities available for sale, gross unrealized losses	-218,000		0
Securities available for sale	93,561,000		13,558,000
Municipal General Obligation Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	132,347,000		16,488,000
Securities available for sale, gross unrealized gains	1,042,000		388,000
Securities available for sale, gross unrealized losses	-307,000		-4,000
Securities available for sale	133,082,000		16,872,000
Municipal Revenue Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	10,769,000		878,000
Securities available for sale, gross unrealized gains	117,000		38,000
Securities available for sale, gross unrealized losses	-13,000		0
Securities available for sale	10,873,000		916,000
Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	1,925,000
Securities available for sale, gross unrealized gains	3,000
Securities available for sale, gross unrealized losses	0
Securities available for sale	1,928,000
Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost			1,386,000
Securities available for sale, gross unrealized gains			0
Securities available for sale, gross unrealized losses			-31,000
Securities available for sale			$1,355,000
[1]	See Note 18 for a description of the fair value hierarchy as well as a disclosure of levels for classes of financial assets and liabilities.

Note_3_Securities_Details_Secu

Note 3 - Securities (Details) - Securities in a Continuous Loss Position (USD $)	Dec. 31, 2014	Dec. 31, 2013
Note 3 - Securities (Details) - Securities in a Continuous Loss Position [Line Items]
Securities available for sale, continuous unrealized loss position, less than 12 months	$190,579,000	$58,767,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	740,000	5,833,000
Securities available for sale, continuous unrealized loss position, 12 months or more	74,120,000	29,679,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	2,836,000	4,267,000
Securities available for sale, continuous unrealized loss position	264,699,000	88,446,000
Securities available for sale, continuous unrealized loss position, unrealized loss	3,576,000	10,100,000
US Government Agencies Debt Securities [Member]
Note 3 - Securities (Details) - Securities in a Continuous Loss Position [Line Items]
Securities available for sale, continuous unrealized loss position, less than 12 months	81,891,000	57,117,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	202,000	5,798,000
Securities available for sale, continuous unrealized loss position, 12 months or more	74,120,000	29,679,000
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	2,836,000	4,267,000
Securities available for sale, continuous unrealized loss position	156,011,000	86,796,000
Securities available for sale, continuous unrealized loss position, unrealized loss	3,038,000	10,065,000
Collateralized Mortgage Backed Securities [Member]
Note 3 - Securities (Details) - Securities in a Continuous Loss Position [Line Items]
Securities available for sale, continuous unrealized loss position, less than 12 months	49,940,000	0
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	218,000	0
Securities available for sale, continuous unrealized loss position, 12 months or more	0	0
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	0	0
Securities available for sale, continuous unrealized loss position	49,940,000	0
Securities available for sale, continuous unrealized loss position, unrealized loss	218,000	0
Municipal General Obligation Bonds [Member]
Note 3 - Securities (Details) - Securities in a Continuous Loss Position [Line Items]
Securities available for sale, continuous unrealized loss position, less than 12 months	54,104,000	295,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	307,000	4,000
Securities available for sale, continuous unrealized loss position, 12 months or more	0	0
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	0	0
Securities available for sale, continuous unrealized loss position	54,104,000	295,000
Securities available for sale, continuous unrealized loss position, unrealized loss	307,000	4,000
Municipal Revenue Bonds [Member]
Note 3 - Securities (Details) - Securities in a Continuous Loss Position [Line Items]
Securities available for sale, continuous unrealized loss position, less than 12 months	4,644,000	0
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	13,000	0
Securities available for sale, continuous unrealized loss position, 12 months or more	0	0
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	0	0
Securities available for sale, continuous unrealized loss position	4,644,000	0
Securities available for sale, continuous unrealized loss position, unrealized loss	13,000	0
Other Debt Obligations [Member]
Note 3 - Securities (Details) - Securities in a Continuous Loss Position [Line Items]
Securities available for sale, continuous unrealized loss position, less than 12 months	0
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss	0
Securities available for sale, continuous unrealized loss position, 12 months or more	0
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss	0
Securities available for sale, continuous unrealized loss position	0
Securities available for sale, continuous unrealized loss position, unrealized loss	0
Mutual Funds [Member]
Note 3 - Securities (Details) - Securities in a Continuous Loss Position [Line Items]
Securities available for sale, continuous unrealized loss position, less than 12 months		1,355,000
Securities available for sale, continuous unrealized loss position, less than 12 months, unrealized loss		31,000
Securities available for sale, continuous unrealized loss position, 12 months or more		0
Securities available for sale, continuous unrealized loss position, 12 months or more, unrealized loss		0
Securities available for sale, continuous unrealized loss position		1,355,000
Securities available for sale, continuous unrealized loss position, unrealized loss		$31,000

Note_3_Securities_Details_Debt

Note 3 - Securities (Details) - Debt Securities by Maturity (USD $)	Dec. 31, 2014
Note 3 - Securities (Details) - Debt Securities by Maturity [Line Items]
Due in one year or less	0.72%
Due in one year or less	$27,651,000
Due in one year or less	27,662,000
Due from one to five years	1.35%
Due from one to five years	148,233,000
Due from one to five years	147,974,000
Due from five to ten years	2.99%
Due from five to ten years	70,282,000
Due from five to ten years	70,191,000
Due after ten years	3.62%
Due after ten years	91,844,000
Due after ten years	91,596,000
	2.17%
	432,591,000
	432,912,000
Collateralized Mortgage Backed Securities [Member]
Note 3 - Securities (Details) - Debt Securities by Maturity [Line Items]
No single maturity, weighted average yield	1.79%
No single maturity, amortized cost	92,656,000
No single maturity, fair value	93,561,000
Other Debt Obligations [Member]
Note 3 - Securities (Details) - Debt Securities by Maturity [Line Items]
No single maturity, weighted average yield	2.57%
No single maturity, amortized cost	1,925,000
No single maturity, fair value	$1,928,000

Note_4_Loans_and_Allowance_for2

Note 4 - Loans and Allowance for Loan Losses (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Receivables [Abstract]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance	$31.40
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	18.6
Impaired Financing Receivable, Interest Income, Accrual Method	1.8	2.5	2
Loans and Leases Receivable, Nonaccrual Loans, Interest Income Recognized		1.9
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	$0.10	$0.40	$0.80
Minimum Number of Days Past Due at Period End for Loans Modified as Troubled Debt Restructurings	30 days	30 days

Note_4_Loans_and_Allowance_for3

Note 4 - Loans and Allowance for Loan Losses (Details) - Components of Loan Portfolio (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	$2,089,277,000	$1,053,243,000	$1,041,189,000
Loans, percentage of portfolio	100.00%	100.00%
Loans, percentage of change in loans	98.40%
Originated Loan [Member] | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	384,570,000	286,373,000
Loans, percentage of portfolio	30.80%	27.20%
Loans, percentage of change in loans	34.30%
Originated Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	29,826,000	36,741,000
Loans, percentage of portfolio	2.40%	3.50%
Loans, percentage of change in loans	-18.80%
Originated Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	291,758,000	261,877,000
Loans, percentage of portfolio	23.40%	24.90%
Loans, percentage of change in loans	11.40%
Originated Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	410,977,000	364,066,000
Loans, percentage of portfolio	33.00%	34.60%
Loans, percentage of change in loans	12.90%
Originated Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	36,058,000	37,639,000
Loans, percentage of portfolio	2.90%	3.50%
Loans, percentage of change in loans	-4.20%
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	1,153,189,000	986,696,000
Loans, percentage of portfolio	92.50%	93.70%
Loans, percentage of change in loans	16.90%
Originated Loan [Member] | Retail Home Equity and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	50,059,000	35,080,000
Loans, percentage of portfolio	4.00%	3.30%
Loans, percentage of change in loans	42.70%
Originated Loan [Member] | Retail 1-4 Family Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	42,868,000	31,467,000
Loans, percentage of portfolio	3.50%	3.00%
Loans, percentage of change in loans	36.20%
Originated Loan [Member] | Retail Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	92,927,000	66,547,000
Loans, percentage of portfolio	7.50%	6.30%
Loans, percentage of change in loans	39.60%
Originated Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	1,246,116,000	1,053,243,000
Loans, percentage of portfolio	100.00%	100.00%
Loans, percentage of change in loans	18.30%
Acquired Loan [Member] | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	166,037,000	0
Loans, percentage of portfolio	19.70%
Loans, percentage of change in loans
Acquired Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	22,148,000	0
Loans, percentage of portfolio	2.60%
Loans, percentage of change in loans
Acquired Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	138,630,000	0
Loans, percentage of portfolio	16.40%
Loans, percentage of change in loans
Acquired Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	148,597,000	0
Loans, percentage of portfolio	17.60%
Loans, percentage of change in loans
Acquired Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	86,702,000	0
Loans, percentage of portfolio	10.30%
Loans, percentage of change in loans
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	562,114,000	0
Loans, percentage of portfolio	66.60%
Loans, percentage of change in loans
Acquired Loan [Member] | Retail Home Equity and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	109,219,000	0
Loans, percentage of portfolio	13.00%
Loans, percentage of change in loans
Acquired Loan [Member] | Retail 1-4 Family Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	171,828,000	0
Loans, percentage of portfolio	20.40%
Loans, percentage of change in loans
Acquired Loan [Member] | Retail Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	281,047,000	0
Loans, percentage of portfolio	33.40%
Loans, percentage of change in loans
Acquired Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	843,161,000	0
Loans, percentage of portfolio	100.00%
Loans, percentage of change in loans
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	550,607,000	286,373,000
Loans, percentage of portfolio	26.40%	27.20%
Loans, percentage of change in loans	92.30%
Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	51,974,000	36,741,000
Loans, percentage of portfolio	2.50%	3.50%
Loans, percentage of change in loans	41.50%
Commercial Real Estate Owner Occupied Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	430,388,000	261,877,000
Loans, percentage of portfolio	20.50%	24.90%
Loans, percentage of change in loans	64.30%
Commercial Real Estate Non Owner Occupied Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	559,574,000	364,066,000
Loans, percentage of portfolio	26.80%	34.60%
Loans, percentage of change in loans	53.70%
Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	122,760,000	37,639,000
Loans, percentage of portfolio	5.90%	3.50%
Loans, percentage of change in loans	226.20%
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	1,715,303,000	986,696,000	968,506,000
Loans, percentage of portfolio	82.10%	93.70%
Loans, percentage of change in loans	73.80%
Retail Home Equity and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	159,278,000	35,080,000
Loans, percentage of portfolio	7.60%	3.30%
Loans, percentage of change in loans	354.00%
Retail 1-4 Family Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	214,696,000	31,467,000
Loans, percentage of portfolio	10.30%	3.00%
Loans, percentage of change in loans	582.30%
Retail Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (in Dollars)	$373,974,000	$66,547,000	$72,683,000
Loans, percentage of portfolio	17.90%	6.30%
Loans, percentage of change in loans	462.00%

Note_4_Loans_and_Allowance_for4

Note 4 - Loans and Allowance for Loan Losses (Details) - Acquired Impaired Loans Accretable Yield (USD $)	7 Months Ended
	Dec. 31, 2014	31-May-14
Acquired Impaired Loans Accretable Yield [Abstract]
Balance	$4,998,000	$0
Additions	2,514,000
Accretion	-786,000
Net reclassification from nonaccretable to accretable	3,537,000
Disposals	-40,000
Other activity	($227,000)

Note_4_Loans_and_Allowance_for5

Note 4 - Loans and Allowance for Loan Losses (Details) - Concentrations Within the Loan Portfolio (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 4 - Loans and Allowance for Loan Losses (Details) - Concentrations Within the Loan Portfolio [Line Items]
Commercial real estate loans to lessors of non-residential buildings	$2,089,277,000	$1,053,243,000	$1,041,189,000
Commercial Real Estate Loans to Lessors of Non-Residential Buildings [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Concentrations Within the Loan Portfolio [Line Items]
Commercial real estate loans to lessors of non-residential buildings	$480,170,000	$299,446,000
Commercial real estate loans to lessors of non-residential buildings	23.00%	28.40%

Note_4_Loans_and_Allowance_for6

Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans (USD $)	Dec. 31, 2014	Dec. 31, 2013
Originated Loan [Member] | Commercial and Industrial [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	$0	$0
Originated Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Retail Home Equity and Other [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Retail 1-4 Family Mortgages [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Retail Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Nonperforming Financing Receivable [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0	0
Nonaccrual loans	26,048,000	6,718,000
Nonperforming loans	26,048,000	6,718,000
Originated Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member] | Commercial and Industrial [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0
Acquired Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0
Acquired Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0
Acquired Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0
Acquired Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0
Acquired Loan [Member] | Retail Home Equity and Other [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	26,000
Acquired Loan [Member] | Retail 1-4 Family Mortgages [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	0
Acquired Loan [Member] | Retail Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	26,000
Acquired Loan [Member] | Nonperforming Financing Receivable [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	26,000
Nonaccrual loans	3,358,000
Nonperforming loans	3,384,000
Acquired Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Loans past due 90 days or more still accruing interest	26,000
Commercial and Industrial [Member] | Nonperforming Financing Receivable [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Nonperforming loans	6,478,000	1,501,000
Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Nonperforming Financing Receivable [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Nonperforming loans	209,000	785,000
Commercial Real Estate Owner Occupied Loan [Member] | Nonperforming Financing Receivable [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Nonperforming loans	18,062,000	389,000
Commercial Real Estate Non Owner Occupied Loan [Member] | Nonperforming Financing Receivable [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Nonperforming loans	378,000	168,000
Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Nonperforming Financing Receivable [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Nonperforming loans	106,000	208,000
Commercial Portfolio Segment [Member] | Nonperforming Financing Receivable [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Nonperforming loans	25,233,000	3,051,000
Retail Home Equity and Other [Member] | Nonperforming Financing Receivable [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Nonperforming loans	800,000	788,000
Retail 1-4 Family Mortgages [Member] | Nonperforming Financing Receivable [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Nonperforming loans	3,399,000	2,879,000
Retail Loan [Member] | Nonperforming Financing Receivable [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Nonperforming loans	4,199,000	3,667,000
Nonperforming Financing Receivable [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Nonperforming Loans [Line Items]
Nonperforming loans	$29,432,000	$6,718,000

Note_4_Loans_and_Allowance_for7

Note 4 - Loans and Allowance for Loan Losses (Details) - Age Analysis of Past Due Loans (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commercial:
Loans	$2,089,277,000	$1,053,243,000	$1,041,189,000
Originated Loan [Member] | Commercial and Industrial [Member]
Commercial:
Loans- 30 to 59 days past due	0	0
Loans- 60 to 89 days past due	0	0
Loans- Greater than 89 days past due	0	309,000
Loans- Total past due	0	309,000
Loans- Current	384,570,000	286,064,000
Loans	384,570,000	286,373,000
Loans- Recorded Balance >89days and accruing	0	0
Originated Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Commercial:
Loans- 30 to 59 days past due	0	0
Loans- 60 to 89 days past due	0	0
Loans- Greater than 89 days past due	0	0
Loans- Total past due	0	0
Loans- Current	29,826,000	36,741,000
Loans	29,826,000	36,741,000
Loans- Recorded Balance >89days and accruing	0	0
Originated Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Commercial:
Loans- 30 to 59 days past due	0	65,000
Loans- 60 to 89 days past due	0	0
Loans- Greater than 89 days past due	120,000	50,000
Loans- Total past due	120,000	115,000
Loans- Current	291,638,000	261,762,000
Loans	291,758,000	261,877,000
Loans- Recorded Balance >89days and accruing	0	0
Originated Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Commercial:
Loans- 30 to 59 days past due	0	0
Loans- 60 to 89 days past due	0	0
Loans- Greater than 89 days past due	116,000	0
Loans- Total past due	116,000	0
Loans- Current	410,861,000	364,066,000
Loans	410,977,000	364,066,000
Loans- Recorded Balance >89days and accruing	0	0
Originated Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Commercial:
Loans- 30 to 59 days past due	0	0
Loans- 60 to 89 days past due	0	0
Loans- Greater than 89 days past due	0	64,000
Loans- Total past due	0	64,000
Loans- Current	36,058,000	37,575,000
Loans	36,058,000	37,639,000
Loans- Recorded Balance >89days and accruing	0	0
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Commercial:
Loans- 30 to 59 days past due	0	65,000
Loans- 60 to 89 days past due	0	0
Loans- Greater than 89 days past due	236,000	423,000
Loans- Total past due	236,000	488,000
Loans- Current	1,152,953,000	986,208,000
Loans	1,153,189,000	986,696,000
Loans- Recorded Balance >89days and accruing	0	0
Originated Loan [Member] | Retail Home Equity and Other [Member]
Commercial:
Loans- 30 to 59 days past due	38,000	14,000
Loans- 60 to 89 days past due	3,000	0
Loans- Greater than 89 days past due	0	0
Loans- Total past due	41,000	14,000
Loans- Current	50,018,000	35,066,000
Loans	50,059,000	35,080,000
Loans- Recorded Balance >89days and accruing	0	0
Originated Loan [Member] | Retail 1-4 Family Mortgages [Member]
Commercial:
Loans- 30 to 59 days past due	0	21,000
Loans- 60 to 89 days past due	0	44,000
Loans- Greater than 89 days past due	366,000	375,000
Loans- Total past due	366,000	440,000
Loans- Current	42,502,000	31,027,000
Loans	42,868,000	31,467,000
Loans- Recorded Balance >89days and accruing	0	0
Originated Loan [Member] | Retail Loan [Member]
Commercial:
Loans- 30 to 59 days past due	38,000	35,000
Loans- 60 to 89 days past due	3,000	44,000
Loans- Greater than 89 days past due	366,000	375,000
Loans- Total past due	407,000	454,000
Loans- Current	92,520,000	66,093,000
Loans	92,927,000	66,547,000
Loans- Recorded Balance >89days and accruing	0	0
Originated Loan [Member]
Commercial:
Loans- 30 to 59 days past due	38,000	100,000
Loans- 60 to 89 days past due	3,000	44,000
Loans- Greater than 89 days past due	602,000	798,000
Loans- Total past due	643,000	942,000
Loans- Current	1,245,473,000	1,052,301,000
Loans	1,246,116,000	1,053,243,000
Loans- Recorded Balance >89days and accruing	0	0
Acquired Loan [Member] | Commercial and Industrial [Member]
Commercial:
Loans- 30 to 59 days past due	29,000
Loans- 60 to 89 days past due	32,000
Loans- Greater than 89 days past due	76,000
Loans- Total past due	137,000
Loans- Current	165,900,000
Loans	166,037,000	0
Loans- Recorded Balance >89days and accruing	0
Acquired Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Commercial:
Loans- 30 to 59 days past due	0
Loans- 60 to 89 days past due	38,000
Loans- Greater than 89 days past due	0
Loans- Total past due	38,000
Loans- Current	22,110,000
Loans	22,148,000	0
Loans- Recorded Balance >89days and accruing	0
Acquired Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Commercial:
Loans- 30 to 59 days past due	51,000
Loans- 60 to 89 days past due	425,000
Loans- Greater than 89 days past due	1,625,000
Loans- Total past due	2,101,000
Loans- Current	136,529,000
Loans	138,630,000	0
Loans- Recorded Balance >89days and accruing	0
Acquired Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Commercial:
Loans- 30 to 59 days past due	68,000
Loans- 60 to 89 days past due	598,000
Loans- Greater than 89 days past due	395,000
Loans- Total past due	1,061,000
Loans- Current	147,536,000
Loans	148,597,000	0
Loans- Recorded Balance >89days and accruing	0
Acquired Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Commercial:
Loans- 30 to 59 days past due	37,000
Loans- 60 to 89 days past due	0
Loans- Greater than 89 days past due	105,000
Loans- Total past due	142,000
Loans- Current	86,560,000
Loans	86,702,000	0
Loans- Recorded Balance >89days and accruing	0
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Commercial:
Loans- 30 to 59 days past due	185,000
Loans- 60 to 89 days past due	1,093,000
Loans- Greater than 89 days past due	2,201,000
Loans- Total past due	3,479,000
Loans- Current	558,635,000
Loans	562,114,000	0
Loans- Recorded Balance >89days and accruing	0
Acquired Loan [Member] | Retail Home Equity and Other [Member]
Commercial:
Loans- 30 to 59 days past due	445,000
Loans- 60 to 89 days past due	419,000
Loans- Greater than 89 days past due	155,000
Loans- Total past due	1,019,000
Loans- Current	108,200,000
Loans	109,219,000	0
Loans- Recorded Balance >89days and accruing	26,000
Acquired Loan [Member] | Retail 1-4 Family Mortgages [Member]
Commercial:
Loans- 30 to 59 days past due	1,087,000
Loans- 60 to 89 days past due	408,000
Loans- Greater than 89 days past due	750,000
Loans- Total past due	2,245,000
Loans- Current	169,583,000
Loans	171,828,000	0
Loans- Recorded Balance >89days and accruing	0
Acquired Loan [Member] | Retail Loan [Member]
Commercial:
Loans- 30 to 59 days past due	1,532,000
Loans- 60 to 89 days past due	827,000
Loans- Greater than 89 days past due	905,000
Loans- Total past due	3,264,000
Loans- Current	277,783,000
Loans	281,047,000	0
Loans- Recorded Balance >89days and accruing	26,000
Acquired Loan [Member]
Commercial:
Loans- 30 to 59 days past due	1,717,000
Loans- 60 to 89 days past due	1,920,000
Loans- Greater than 89 days past due	3,106,000
Loans- Total past due	6,743,000
Loans- Current	836,418,000
Loans	843,161,000	0
Loans- Recorded Balance >89days and accruing	26,000
Commercial and Industrial [Member]
Commercial:
Loans	550,607,000	286,373,000
Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Commercial:
Loans	51,974,000	36,741,000
Commercial Real Estate Owner Occupied Loan [Member]
Commercial:
Loans	430,388,000	261,877,000
Commercial Real Estate Non Owner Occupied Loan [Member]
Commercial:
Loans	559,574,000	364,066,000
Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Commercial:
Loans	122,760,000	37,639,000
Commercial Portfolio Segment [Member]
Commercial:
Loans	1,715,303,000	986,696,000	968,506,000
Retail Home Equity and Other [Member]
Commercial:
Loans	159,278,000	35,080,000
Retail 1-4 Family Mortgages [Member]
Commercial:
Loans	214,696,000	31,467,000
Retail Loan [Member]
Commercial:
Loans	$373,974,000	$66,547,000	$72,683,000

Note_4_Loans_and_Allowance_for8

Note 4 - Loans and Allowance for Loan Losses (Details) - Impaired Loans (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		$12,386,000
Commercial:
Impaired loans, related allowance		12,386,000
Total impaired loans:
Impaired loans, unpaid contractual principal balance		41,056,000
Impaired loans, recorded principal balance		36,868,000
Impaired loans, related allowance		12,386,000
Impaired loans, average recorded principal balance		49,961,000
Originated Loan [Member] | With No Related Allowance [Member] | Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	1,170,000	2,229,000
Impaired loans with no related allowance recorded, recorded principal balance	1,164,000	511,000
Impaired loans with no related allowance recorded, average recorded principal balance	652,000	1,205,000
Originated Loan [Member] | With No Related Allowance [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	540,000	475,000
Impaired loans with no related allowance recorded, recorded principal balance	209,000	362,000
Impaired loans with no related allowance recorded, average recorded principal balance	227,000	991,000
Originated Loan [Member] | With No Related Allowance [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	3,609,000	1,270,000
Impaired loans with no related allowance recorded, recorded principal balance	1,901,000	785,000
Impaired loans with no related allowance recorded, average recorded principal balance	4,365,000	1,084,000
Originated Loan [Member] | With No Related Allowance [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	1,210,000	895,000
Impaired loans with no related allowance recorded, recorded principal balance	1,210,000	733,000
Impaired loans with no related allowance recorded, average recorded principal balance	971,000	4,049,000
Originated Loan [Member] | With No Related Allowance [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	375,000	41,000
Impaired loans with no related allowance recorded, recorded principal balance	317,000	1,000
Impaired loans with no related allowance recorded, average recorded principal balance	64,000	390,000
Originated Loan [Member] | With No Related Allowance [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	6,904,000	4,910,000
Impaired loans with no related allowance recorded, recorded principal balance	4,801,000	2,392,000
Impaired loans with no related allowance recorded, average recorded principal balance	6,279,000	7,719,000
Originated Loan [Member] | With No Related Allowance [Member] | Retail Home Equity and Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	207,000	507,000
Impaired loans with no related allowance recorded, recorded principal balance	191,000	461,000
Impaired loans with no related allowance recorded, average recorded principal balance	517,000	471,000
Originated Loan [Member] | With No Related Allowance [Member] | Retail 1-4 Family Mortgages [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	1,144,000	1,272,000
Impaired loans with no related allowance recorded, recorded principal balance	560,000	647,000
Impaired loans with no related allowance recorded, average recorded principal balance	585,000	727,000
Originated Loan [Member] | With No Related Allowance [Member] | Retail Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	1,351,000	1,779,000
Impaired loans with no related allowance recorded, recorded principal balance	751,000	1,108,000
Impaired loans with no related allowance recorded, average recorded principal balance	1,102,000	1,198,000
Originated Loan [Member] | With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	8,255,000	6,689,000
Impaired loans with no related allowance recorded, recorded principal balance	5,552,000	3,500,000
Impaired loans with no related allowance recorded, related allowance	0	0
Impaired loans with no related allowance recorded, average recorded principal balance	7,381,000	8,917,000
Commercial:
Impaired loans, related allowance	0	0
Total impaired loans:
Impaired loans, related allowance	0	0
Originated Loan [Member] | With An Allowance Recorded [Member] | Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	1,578,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	5,299,000
Impaired loans with an allowance recorded, recorded principal balance	5,226,000
Impaired loans, related allowance	1,578,000
Impaired loans with an allowance recorded, average recorded principal balance	2,759,000
Total impaired loans:
Impaired loans, related allowance	1,578,000
Originated Loan [Member] | With An Allowance Recorded [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	151,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	2,000,000
Impaired loans with an allowance recorded, recorded principal balance	2,000,000
Impaired loans, related allowance	151,000
Impaired loans with an allowance recorded, average recorded principal balance	3,229,000
Total impaired loans:
Impaired loans, related allowance	151,000
Originated Loan [Member] | With An Allowance Recorded [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	2,200,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	15,745,000
Impaired loans with an allowance recorded, recorded principal balance	15,674,000
Impaired loans, related allowance	2,200,000
Impaired loans with an allowance recorded, average recorded principal balance	4,630,000
Total impaired loans:
Impaired loans, related allowance	2,200,000
Originated Loan [Member] | With An Allowance Recorded [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	4,779,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	16,033,000
Impaired loans with an allowance recorded, recorded principal balance	15,949,000
Impaired loans, related allowance	4,779,000
Impaired loans with an allowance recorded, average recorded principal balance	18,245,000
Total impaired loans:
Impaired loans, related allowance	4,779,000
Originated Loan [Member] | With An Allowance Recorded [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	666,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	1,371,000
Impaired loans with an allowance recorded, recorded principal balance	1,371,000
Impaired loans, related allowance	666,000
Impaired loans with an allowance recorded, average recorded principal balance	1,700,000
Total impaired loans:
Impaired loans, related allowance	666,000
Originated Loan [Member] | With An Allowance Recorded [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	9,374,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	40,448,000
Impaired loans with an allowance recorded, recorded principal balance	40,220,000
Impaired loans, related allowance	9,374,000
Impaired loans with an allowance recorded, average recorded principal balance	30,563,000
Total impaired loans:
Impaired loans, related allowance	9,374,000
Originated Loan [Member] | With An Allowance Recorded [Member] | Retail Home Equity and Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	84,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	115,000
Impaired loans with an allowance recorded, recorded principal balance	84,000
Impaired loans, related allowance	84,000
Impaired loans with an allowance recorded, average recorded principal balance	128,000
Total impaired loans:
Impaired loans, related allowance	84,000
Originated Loan [Member] | With An Allowance Recorded [Member] | Retail 1-4 Family Mortgages [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	694,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	2,194,000
Impaired loans with an allowance recorded, recorded principal balance	2,000,000
Impaired loans, related allowance	694,000
Impaired loans with an allowance recorded, average recorded principal balance	2,115,000
Total impaired loans:
Impaired loans, related allowance	694,000
Originated Loan [Member] | With An Allowance Recorded [Member] | Retail Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	778,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	2,309,000
Impaired loans with an allowance recorded, recorded principal balance	2,084,000
Impaired loans, related allowance	778,000
Impaired loans with an allowance recorded, average recorded principal balance	2,243,000
Total impaired loans:
Impaired loans, related allowance	778,000
Originated Loan [Member] | With An Allowance Recorded [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	10,152,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	42,757,000
Impaired loans with an allowance recorded, recorded principal balance	42,304,000
Impaired loans, related allowance	10,152,000
Impaired loans with an allowance recorded, average recorded principal balance	32,806,000
Total impaired loans:
Impaired loans, related allowance	10,152,000
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	9,374,000
Commercial:
Impaired loans, related allowance	9,374,000
Total impaired loans:
Impaired loans, unpaid contractual principal balance	47,352,000
Impaired loans, recorded principal balance	45,021,000
Impaired loans, related allowance	9,374,000
Impaired loans, average recorded principal balance	36,842,000
Originated Loan [Member] | Retail Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	778,000
Commercial:
Impaired loans, related allowance	778,000
Total impaired loans:
Impaired loans, unpaid contractual principal balance	3,660,000
Impaired loans, recorded principal balance	2,835,000
Impaired loans, related allowance	778,000
Impaired loans, average recorded principal balance	3,345,000
Originated Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	10,152,000
Commercial:
Impaired loans, related allowance	10,152,000
Total impaired loans:
Impaired loans, unpaid contractual principal balance	51,012,000
Impaired loans, recorded principal balance	47,856,000
Impaired loans, related allowance	10,152,000
Impaired loans, average recorded principal balance	40,187,000
Acquired Loan [Member] | With No Related Allowance [Member] | Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	1,586,000
Impaired loans with no related allowance recorded, recorded principal balance	1,579,000
Impaired loans with no related allowance recorded, average recorded principal balance	563,000
Acquired Loan [Member] | With No Related Allowance [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	0
Impaired loans with no related allowance recorded, recorded principal balance	0
Impaired loans with no related allowance recorded, average recorded principal balance	0
Acquired Loan [Member] | With No Related Allowance [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	113,000
Impaired loans with no related allowance recorded, recorded principal balance	113,000
Impaired loans with no related allowance recorded, average recorded principal balance	52,000
Acquired Loan [Member] | With No Related Allowance [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	326,000
Impaired loans with no related allowance recorded, recorded principal balance	326,000
Impaired loans with no related allowance recorded, average recorded principal balance	260,000
Acquired Loan [Member] | With No Related Allowance [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	487,000
Impaired loans with no related allowance recorded, recorded principal balance	487,000
Impaired loans with no related allowance recorded, average recorded principal balance	166,000
Acquired Loan [Member] | With No Related Allowance [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	2,512,000
Impaired loans with no related allowance recorded, recorded principal balance	2,505,000
Impaired loans with no related allowance recorded, average recorded principal balance	1,041,000
Acquired Loan [Member] | With No Related Allowance [Member] | Retail Home Equity and Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	641,000
Impaired loans with no related allowance recorded, recorded principal balance	639,000
Impaired loans with no related allowance recorded, average recorded principal balance	262,000
Acquired Loan [Member] | With No Related Allowance [Member] | Retail 1-4 Family Mortgages [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	866,000
Impaired loans with no related allowance recorded, recorded principal balance	866,000
Impaired loans with no related allowance recorded, average recorded principal balance	458,000
Acquired Loan [Member] | With No Related Allowance [Member] | Retail Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	1,507,000
Impaired loans with no related allowance recorded, recorded principal balance	1,505,000
Impaired loans with no related allowance recorded, average recorded principal balance	720,000
Acquired Loan [Member] | With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, unpaid contractual principal balance	4,019,000
Impaired loans with no related allowance recorded, recorded principal balance	4,010,000
Impaired loans with no related allowance recorded, related allowance	0
Impaired loans with no related allowance recorded, average recorded principal balance	1,761,000
Commercial:
Impaired loans, related allowance	0
Total impaired loans:
Impaired loans, related allowance	0
Acquired Loan [Member] | With An Allowance Recorded [Member] | Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	0
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	0
Impaired loans with an allowance recorded, recorded principal balance	0
Impaired loans, related allowance	0
Impaired loans with an allowance recorded, average recorded principal balance	0
Total impaired loans:
Impaired loans, related allowance	0
Acquired Loan [Member] | With An Allowance Recorded [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	0
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	0
Impaired loans with an allowance recorded, recorded principal balance	0
Impaired loans, related allowance	0
Impaired loans with an allowance recorded, average recorded principal balance	0
Total impaired loans:
Impaired loans, related allowance	0
Acquired Loan [Member] | With An Allowance Recorded [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	605,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	1,516,000
Impaired loans with an allowance recorded, recorded principal balance	1,502,000
Impaired loans, related allowance	605,000
Impaired loans with an allowance recorded, average recorded principal balance	501,000
Total impaired loans:
Impaired loans, related allowance	605,000
Acquired Loan [Member] | With An Allowance Recorded [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	0
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	0
Impaired loans with an allowance recorded, recorded principal balance	0
Impaired loans, related allowance	0
Impaired loans with an allowance recorded, average recorded principal balance	0
Total impaired loans:
Impaired loans, related allowance	0
Acquired Loan [Member] | With An Allowance Recorded [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	0
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	0
Impaired loans with an allowance recorded, recorded principal balance	0
Impaired loans, related allowance	0
Impaired loans with an allowance recorded, average recorded principal balance	0
Total impaired loans:
Impaired loans, related allowance	0
Acquired Loan [Member] | With An Allowance Recorded [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	605,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	1,516,000
Impaired loans with an allowance recorded, recorded principal balance	1,502,000
Impaired loans, related allowance	605,000
Impaired loans with an allowance recorded, average recorded principal balance	501,000
Total impaired loans:
Impaired loans, related allowance	605,000
Acquired Loan [Member] | With An Allowance Recorded [Member] | Retail Home Equity and Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	0
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	0
Impaired loans with an allowance recorded, recorded principal balance	0
Impaired loans, related allowance	0
Impaired loans with an allowance recorded, average recorded principal balance	0
Total impaired loans:
Impaired loans, related allowance	0
Acquired Loan [Member] | With An Allowance Recorded [Member] | Retail 1-4 Family Mortgages [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	0
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	0
Impaired loans with an allowance recorded, recorded principal balance	0
Impaired loans, related allowance	0
Impaired loans with an allowance recorded, average recorded principal balance	0
Total impaired loans:
Impaired loans, related allowance	0
Acquired Loan [Member] | With An Allowance Recorded [Member] | Retail Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	0
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	0
Impaired loans with an allowance recorded, recorded principal balance	0
Impaired loans, related allowance	0
Impaired loans with an allowance recorded, average recorded principal balance	0
Total impaired loans:
Impaired loans, related allowance	0
Acquired Loan [Member] | With An Allowance Recorded [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	605,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance	1,516,000
Impaired loans with an allowance recorded, recorded principal balance	1,502,000
Impaired loans, related allowance	605,000
Impaired loans with an allowance recorded, average recorded principal balance	501,000
Total impaired loans:
Impaired loans, related allowance	605,000
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	605,000
Commercial:
Impaired loans, related allowance	605,000
Total impaired loans:
Impaired loans, unpaid contractual principal balance	4,028,000
Impaired loans, recorded principal balance	4,007,000
Impaired loans, related allowance	605,000
Impaired loans, average recorded principal balance	1,542,000
Acquired Loan [Member] | Retail Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	0
Commercial:
Impaired loans, related allowance	0
Total impaired loans:
Impaired loans, unpaid contractual principal balance	1,507,000
Impaired loans, recorded principal balance	1,505,000
Impaired loans, related allowance	0
Impaired loans, average recorded principal balance	720,000
Acquired Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance	605,000
Commercial:
Impaired loans, related allowance	605,000
Total impaired loans:
Impaired loans, unpaid contractual principal balance	5,535,000
Impaired loans, recorded principal balance	5,512,000
Impaired loans, related allowance	605,000
Impaired loans, average recorded principal balance	2,262,000
With An Allowance Recorded [Member] | Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		792,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance		1,517,000
Impaired loans with an allowance recorded, recorded principal balance		1,440,000
Impaired loans, related allowance		792,000
Impaired loans with an allowance recorded, average recorded principal balance		1,880,000
Total impaired loans:
Impaired loans, related allowance		792,000
With An Allowance Recorded [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		844,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance		4,436,000
Impaired loans with an allowance recorded, recorded principal balance		4,139,000
Impaired loans, related allowance		844,000
Impaired loans with an allowance recorded, average recorded principal balance		3,354,000
Total impaired loans:
Impaired loans, related allowance		844,000
With An Allowance Recorded [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		528,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance		1,513,000
Impaired loans with an allowance recorded, recorded principal balance		1,513,000
Impaired loans, related allowance		528,000
Impaired loans with an allowance recorded, average recorded principal balance		2,550,000
Total impaired loans:
Impaired loans, related allowance		528,000
With An Allowance Recorded [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		7,969,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance		21,088,000
Impaired loans with an allowance recorded, recorded principal balance		21,072,000
Impaired loans, related allowance		7,969,000
Impaired loans with an allowance recorded, average recorded principal balance		28,388,000
Total impaired loans:
Impaired loans, related allowance		7,969,000
With An Allowance Recorded [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		1,127,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance		3,219,000
Impaired loans with an allowance recorded, recorded principal balance		2,684,000
Impaired loans, related allowance		1,127,000
Impaired loans with an allowance recorded, average recorded principal balance		2,915,000
Total impaired loans:
Impaired loans, related allowance		1,127,000
With An Allowance Recorded [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		11,260,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance		31,773,000
Impaired loans with an allowance recorded, recorded principal balance		30,848,000
Impaired loans, related allowance		11,260,000
Impaired loans with an allowance recorded, average recorded principal balance		39,087,000
Total impaired loans:
Impaired loans, related allowance		11,260,000
With An Allowance Recorded [Member] | Retail Home Equity and Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		96,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance		320,000
Impaired loans with an allowance recorded, recorded principal balance		289,000
Impaired loans, related allowance		96,000
Impaired loans with an allowance recorded, average recorded principal balance		329,000
Total impaired loans:
Impaired loans, related allowance		96,000
With An Allowance Recorded [Member] | Retail 1-4 Family Mortgages [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		1,030,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance		2,274,000
Impaired loans with an allowance recorded, recorded principal balance		2,231,000
Impaired loans, related allowance		1,030,000
Impaired loans with an allowance recorded, average recorded principal balance		1,628,000
Total impaired loans:
Impaired loans, related allowance		1,030,000
With An Allowance Recorded [Member] | Retail Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		1,126,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance		2,594,000
Impaired loans with an allowance recorded, recorded principal balance		2,520,000
Impaired loans, related allowance		1,126,000
Impaired loans with an allowance recorded, average recorded principal balance		1,957,000
Total impaired loans:
Impaired loans, related allowance		1,126,000
With An Allowance Recorded [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		12,386,000
Commercial:
Impaired loans with an allowance recorded, unpaid contractual principal balance		34,367,000
Impaired loans with an allowance recorded, recorded principal balance		33,368,000
Impaired loans, related allowance		12,386,000
Impaired loans with an allowance recorded, average recorded principal balance		41,044,000
Total impaired loans:
Impaired loans, related allowance		12,386,000
Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		11,260,000
Commercial:
Impaired loans, related allowance		11,260,000
Total impaired loans:
Impaired loans, unpaid contractual principal balance		36,683,000
Impaired loans, recorded principal balance		33,240,000
Impaired loans, related allowance		11,260,000
Impaired loans, average recorded principal balance		46,806,000
Retail Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance recorded, related allowance		1,126,000
Commercial:
Impaired loans, related allowance		1,126,000
Total impaired loans:
Impaired loans, unpaid contractual principal balance		4,373,000
Impaired loans, recorded principal balance		3,628,000
Impaired loans, related allowance		1,126,000
Impaired loans, average recorded principal balance		$3,155,000

Note_4_Loans_and_Allowance_for9

Note 4 - Loans and Allowance for Loan Losses (Details) - Loans by Credit Quality Indicators (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Internal credit risk grade groupings:
Loans	$2,089,277,000	$1,053,243,000	$1,041,189,000
Originated Loan [Member] | Commercial and Industrial [Member] | Grade 1 - 4 [Member]
Internal credit risk grade groupings:
Loans	266,631,000	208,151,000
Originated Loan [Member] | Commercial and Industrial [Member] | Grade 5 - 7 [Member]
Internal credit risk grade groupings:
Loans	109,639,000	76,237,000
Originated Loan [Member] | Commercial and Industrial [Member] | Grade 8 - 9 [Member]
Internal credit risk grade groupings:
Loans	8,300,000	1,985,000
Originated Loan [Member] | Commercial and Industrial [Member]
Internal credit risk grade groupings:
Loans	384,570,000	286,373,000
Originated Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Grade 1 - 4 [Member]
Internal credit risk grade groupings:
Loans	11,242,000	6,973,000
Originated Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Grade 5 - 7 [Member]
Internal credit risk grade groupings:
Loans	16,375,000	25,535,000
Originated Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Grade 8 - 9 [Member]
Internal credit risk grade groupings:
Loans	2,209,000	4,233,000
Originated Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Internal credit risk grade groupings:
Loans	29,826,000	36,741,000
Originated Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member] | Grade 1 - 4 [Member]
Internal credit risk grade groupings:
Loans	190,656,000	156,230,000
Originated Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member] | Grade 5 - 7 [Member]
Internal credit risk grade groupings:
Loans	83,123,000	103,066,000
Originated Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member] | Grade 8 - 9 [Member]
Internal credit risk grade groupings:
Loans	17,979,000	2,581,000
Originated Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Internal credit risk grade groupings:
Loans	291,758,000	261,877,000
Originated Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member] | Grade 1 - 4 [Member]
Internal credit risk grade groupings:
Loans	285,035,000	219,325,000
Originated Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member] | Grade 5 - 7 [Member]
Internal credit risk grade groupings:
Loans	113,982,000	122,717,000
Originated Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member] | Grade 8 - 9 [Member]
Internal credit risk grade groupings:
Loans	11,960,000	22,024,000
Originated Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Internal credit risk grade groupings:
Loans	410,977,000	364,066,000
Originated Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Grade 1 - 4 [Member]
Internal credit risk grade groupings:
Loans	12,394,000	15,465,000
Originated Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Grade 5 - 7 [Member]
Internal credit risk grade groupings:
Loans	22,282,000	19,469,000
Originated Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Grade 8 - 9 [Member]
Internal credit risk grade groupings:
Loans	1,382,000	2,705,000
Originated Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Internal credit risk grade groupings:
Loans	36,058,000	37,639,000
Originated Loan [Member]
Internal credit risk grade groupings:
Loans	1,246,116,000	1,053,243,000
Acquired Loan [Member] | Commercial and Industrial [Member] | Grade 1 - 4 [Member]
Internal credit risk grade groupings:
Loans	72,411,000
Acquired Loan [Member] | Commercial and Industrial [Member] | Grade 5 - 7 [Member]
Internal credit risk grade groupings:
Loans	90,320,000
Acquired Loan [Member] | Commercial and Industrial [Member] | Grade 8 - 9 [Member]
Internal credit risk grade groupings:
Loans	3,306,000
Acquired Loan [Member] | Commercial and Industrial [Member]
Internal credit risk grade groupings:
Loans	166,037,000	0
Acquired Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Grade 1 - 4 [Member]
Internal credit risk grade groupings:
Loans	5,875,000
Acquired Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Grade 5 - 7 [Member]
Internal credit risk grade groupings:
Loans	14,472,000
Acquired Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Grade 8 - 9 [Member]
Internal credit risk grade groupings:
Loans	1,801,000
Acquired Loan [Member] | Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Internal credit risk grade groupings:
Loans	22,148,000	0
Acquired Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member] | Grade 1 - 4 [Member]
Internal credit risk grade groupings:
Loans	39,496,000
Acquired Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member] | Grade 5 - 7 [Member]
Internal credit risk grade groupings:
Loans	92,212,000
Acquired Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member] | Grade 8 - 9 [Member]
Internal credit risk grade groupings:
Loans	6,922,000
Acquired Loan [Member] | Commercial Real Estate Owner Occupied Loan [Member]
Internal credit risk grade groupings:
Loans	138,630,000	0
Acquired Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member] | Grade 1 - 4 [Member]
Internal credit risk grade groupings:
Loans	65,886,000
Acquired Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member] | Grade 5 - 7 [Member]
Internal credit risk grade groupings:
Loans	78,103,000
Acquired Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member] | Grade 8 - 9 [Member]
Internal credit risk grade groupings:
Loans	4,608,000
Acquired Loan [Member] | Commercial Real Estate Non Owner Occupied Loan [Member]
Internal credit risk grade groupings:
Loans	148,597,000	0
Acquired Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Grade 1 - 4 [Member]
Internal credit risk grade groupings:
Loans	35,858,000
Acquired Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Grade 5 - 7 [Member]
Internal credit risk grade groupings:
Loans	49,781,000
Acquired Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Grade 8 - 9 [Member]
Internal credit risk grade groupings:
Loans	1,063,000
Acquired Loan [Member] | Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Internal credit risk grade groupings:
Loans	86,702,000	0
Acquired Loan [Member]
Internal credit risk grade groupings:
Loans	843,161,000	0
Commercial and Industrial [Member]
Internal credit risk grade groupings:
Loans	550,607,000	286,373,000
Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Internal credit risk grade groupings:
Loans	51,974,000	36,741,000
Commercial Real Estate Owner Occupied Loan [Member]
Internal credit risk grade groupings:
Loans	430,388,000	261,877,000
Commercial Real Estate Non Owner Occupied Loan [Member]
Internal credit risk grade groupings:
Loans	559,574,000	364,066,000
Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Internal credit risk grade groupings:
Loans	$122,760,000	$37,639,000

Recovered_Sheet1

Note 4 - Loans and Allowance for Loan Losses (Details) - Retail Credit Risk by Collateral Type (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Total retail	$2,089,277,000	$1,053,243,000	$1,041,189,000
Originated Loan [Member] | Retail Home Equity and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total retail	50,059,000	35,080,000
Originated Loan [Member] | Retail 1-4 Family Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Total retail	42,868,000	31,467,000
Originated Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Total retail	1,246,116,000	1,053,243,000
Acquired Loan [Member] | Retail Home Equity and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total retail	109,219,000	0
Acquired Loan [Member] | Retail 1-4 Family Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Total retail	171,828,000	0
Acquired Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Total retail	843,161,000	0
Retail Home Equity and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total retail	159,278,000	35,080,000
Retail 1-4 Family Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Total retail	$214,696,000	$31,467,000

Recovered_Sheet2

Note 4 - Loans and Allowance for Loan Losses (Details) - Activity in Allowance for Loan Losses and the Recorded Investments in Loans (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	$22,821,000	$28,677,000	$36,532,000
Allowance for loan losses: individually evaluated for impairment		12,386,000	17,189,000
Allowance for loan losses: collectively evaluated for impairment		10,435,000	11,488,000
Total loans:
Loans	2,089,277,000	1,053,243,000	1,041,189,000
Loans: individually evaluated for impairment		36,868,000	57,279,000
Loans: collectively evaluated for impairment		1,016,375,000	983,910,000
Provision for loan losses	-3,000,000	-7,200,000	-3,100,000
Charge-offs		-5,290,000	-12,644,000
Recoveries		6,634,000	7,889,000
Allowance for loan losses		22,821,000	28,677,000
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	20,455,000
Allowance for loan losses: individually evaluated for impairment	9,374,000
Allowance for loan losses: collectively evaluated for impairment	8,362,000
Total loans:
Loans	1,153,189,000	986,696,000
Loans: individually evaluated for impairment	45,021,000
Loans: collectively evaluated for impairment	1,108,168,000
Provision for loan losses	-3,140,000
Charge-offs	-876,000
Recoveries	1,297,000
Allowance for loan losses	17,736,000
Originated Loan [Member] | Retail Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	2,358,000
Allowance for loan losses: individually evaluated for impairment	777,000
Allowance for loan losses: collectively evaluated for impairment	710,000
Total loans:
Loans	92,927,000	66,547,000
Loans: individually evaluated for impairment	2,835,000
Loans: collectively evaluated for impairment	90,092,000
Provision for loan losses	-721,000
Charge-offs	-554,000
Recoveries	404,000
Allowance for loan losses	1,487,000
Originated Loan [Member] | Unallocated Financing Receivables [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	8,000
Allowance for loan losses: individually evaluated for impairment	0
Allowance for loan losses: collectively evaluated for impairment	76,000
Total loans:
Provision for loan losses	68,000
Charge-offs	0
Recoveries	0
Allowance for loan losses	76,000
Originated Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	22,821,000
Allowance for loan losses: individually evaluated for impairment	10,151,000
Allowance for loan losses: collectively evaluated for impairment	9,148,000
Total loans:
Loans	1,246,116,000	1,053,243,000
Loans: individually evaluated for impairment	47,856,000
Loans: collectively evaluated for impairment	1,198,260,000
Provision for loan losses	-3,793,000
Charge-offs	-1,430,000
Recoveries	1,701,000
Allowance for loan losses	19,299,000
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	0
Total loans:
Loans	562,114,000	0
Provision for loan losses	734,000
Charge-offs	-55,000
Recoveries	2,000
Allowance for loan losses	681,000
Acquired Loan [Member] | Retail Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	0
Total loans:
Loans	281,047,000	0
Provision for loan losses	59,000
Charge-offs	-16,000
Recoveries	18,000
Allowance for loan losses	61,000
Acquired Loan [Member] | Unallocated Financing Receivables [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	0
Total loans:
Provision for loan losses	0
Charge-offs	0
Recoveries	0
Allowance for loan losses	0
Acquired Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	0
Total loans:
Loans	843,161,000	0
Provision for loan losses	793,000
Charge-offs	-71,000
Recoveries	20,000
Allowance for loan losses	742,000
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses		26,043,000	33,431,000
Allowance for loan losses: individually evaluated for impairment		11,260,000	16,860,000
Allowance for loan losses: collectively evaluated for impairment		9,195,000	9,183,000
Total loans:
Loans	1,715,303,000	986,696,000	968,506,000
Loans: individually evaluated for impairment		33,240,000	55,138,000
Loans: collectively evaluated for impairment		953,456,000	913,368,000
Provision for loan losses		-6,730,000	-2,800,000
Charge-offs		-5,120,000	-12,075,000
Recoveries		6,262,000	7,487,000
Allowance for loan losses		20,455,000	26,043,000
Retail Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses		2,645,000	3,019,000
Allowance for loan losses: individually evaluated for impairment		1,126,000	329,000
Allowance for loan losses: collectively evaluated for impairment		1,232,000	2,316,000
Total loans:
Loans	373,974,000	66,547,000	72,683,000
Loans: individually evaluated for impairment		3,628,000	2,141,000
Loans: collectively evaluated for impairment		62,919,000	70,542,000
Provision for loan losses		-489,000	-207,000
Charge-offs		-170,000	-569,000
Recoveries		372,000	402,000
Allowance for loan losses		2,358,000	2,645,000
Unallocated Financing Receivables [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses		-11,000	82,000
Allowance for loan losses: individually evaluated for impairment		0	0
Allowance for loan losses: collectively evaluated for impairment		8,000	-11,000
Total loans:
Provision for loan losses		19,000	-93,000
Charge-offs		0	0
Recoveries		0	0
Allowance for loan losses		$8,000	($11,000)

Recovered_Sheet3

Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Commercial:
Loans modified, number of contracts		10
Loans modified, pre-modification recorded principal balance		$7,231,000
Loans modified, post-modification recorded principal balance		7,231,000
Commercial and Industrial [Member] | Originated Loan [Member]
Commercial:
Loans modified, number of contracts	2	3
Loans modified, pre-modification recorded principal balance	5,994,000	741,000
Loans modified, post-modification recorded principal balance	6,094,000	741,000
Commercial and Industrial [Member] | Acquired Loan [Member]
Commercial:
Loans modified, number of contracts	7
Loans modified, pre-modification recorded principal balance	1,604,000
Loans modified, post-modification recorded principal balance	1,604,000
Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Originated Loan [Member]
Commercial:
Loans modified, number of contracts	0	2
Loans modified, pre-modification recorded principal balance	0	3,610,000
Loans modified, post-modification recorded principal balance	0	3,610,000
Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Acquired Loan [Member]
Commercial:
Loans modified, number of contracts	0
Loans modified, pre-modification recorded principal balance	0
Loans modified, post-modification recorded principal balance	0
Commercial Real Estate Owner Occupied Loan [Member] | Originated Loan [Member]
Commercial:
Loans modified, number of contracts	2	2
Loans modified, pre-modification recorded principal balance	16,787,000	715,000
Loans modified, post-modification recorded principal balance	16,787,000	715,000
Commercial Real Estate Owner Occupied Loan [Member] | Acquired Loan [Member]
Commercial:
Loans modified, number of contracts	2
Loans modified, pre-modification recorded principal balance	1,619,000
Loans modified, post-modification recorded principal balance	1,619,000
Commercial Real Estate Non Owner Occupied Loan [Member] | Originated Loan [Member]
Commercial:
Loans modified, number of contracts	1	1
Loans modified, pre-modification recorded principal balance	146,000	45,000
Loans modified, post-modification recorded principal balance	146,000	45,000
Commercial Real Estate Non Owner Occupied Loan [Member] | Acquired Loan [Member]
Commercial:
Loans modified, number of contracts	1
Loans modified, pre-modification recorded principal balance	65,000
Loans modified, post-modification recorded principal balance	65,000
Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Originated Loan [Member]
Commercial:
Loans modified, number of contracts	0	1
Loans modified, pre-modification recorded principal balance	0	241,000
Loans modified, post-modification recorded principal balance	0	241,000
Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Acquired Loan [Member]
Commercial:
Loans modified, number of contracts	4
Loans modified, pre-modification recorded principal balance	394,000
Loans modified, post-modification recorded principal balance	394,000
Commercial Portfolio Segment [Member] | Originated Loan [Member]
Commercial:
Loans modified, number of contracts	5	9
Loans modified, pre-modification recorded principal balance	22,927,000	5,352,000
Loans modified, post-modification recorded principal balance	23,027,000	5,352,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Commercial:
Loans modified, number of contracts	14
Loans modified, pre-modification recorded principal balance	3,682,000
Loans modified, post-modification recorded principal balance	3,682,000
Retail Home Equity and Other [Member] | Originated Loan [Member]
Commercial:
Loans modified, number of contracts	0
Loans modified, pre-modification recorded principal balance	0
Loans modified, post-modification recorded principal balance	0
Retail Home Equity and Other [Member] | Acquired Loan [Member]
Commercial:
Loans modified, number of contracts	1
Loans modified, pre-modification recorded principal balance	26,000
Loans modified, post-modification recorded principal balance	26,000
Retail Home Equity and Other [Member]
Commercial:
Loans modified, number of contracts		0
Loans modified, pre-modification recorded principal balance		0
Loans modified, post-modification recorded principal balance		0
Retail 1-4 Family Mortgages [Member] | Originated Loan [Member]
Commercial:
Loans modified, number of contracts	0
Loans modified, pre-modification recorded principal balance	0
Loans modified, post-modification recorded principal balance	0
Retail 1-4 Family Mortgages [Member] | Acquired Loan [Member]
Commercial:
Loans modified, number of contracts	1
Loans modified, pre-modification recorded principal balance	179,000
Loans modified, post-modification recorded principal balance	179,000
Retail 1-4 Family Mortgages [Member]
Commercial:
Loans modified, number of contracts		1
Loans modified, pre-modification recorded principal balance		1,879,000
Loans modified, post-modification recorded principal balance		1,879,000
Retail Loan [Member] | Originated Loan [Member]
Commercial:
Loans modified, number of contracts	0
Loans modified, pre-modification recorded principal balance	0
Loans modified, post-modification recorded principal balance	0
Retail Loan [Member] | Acquired Loan [Member]
Commercial:
Loans modified, number of contracts	2
Loans modified, pre-modification recorded principal balance	205,000
Loans modified, post-modification recorded principal balance	205,000
Retail Loan [Member]
Commercial:
Loans modified, number of contracts		1
Loans modified, pre-modification recorded principal balance		1,879,000
Loans modified, post-modification recorded principal balance		1,879,000
Originated Loan [Member]
Commercial:
Loans modified, number of contracts	5
Loans modified, pre-modification recorded principal balance	22,927,000
Loans modified, post-modification recorded principal balance	23,027,000
Acquired Loan [Member]
Commercial:
Loans modified, number of contracts	16
Loans modified, pre-modification recorded principal balance	3,887,000
Loans modified, post-modification recorded principal balance	$3,887,000

Recovered_Sheet4

Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due (USD $)	12 Months Ended		7 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014
Commercial and Industrial [Member] | Originated Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts	0	0
Recorded principal balance	$0	$0
Commercial and Industrial [Member] | Acquired Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts			0
Recorded principal balance			0
Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Originated Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts	0	0
Recorded principal balance	0	0
Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Acquired Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts			0
Recorded principal balance			0
Commercial Real Estate Owner Occupied Loan [Member] | Originated Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts	0	1
Recorded principal balance	0	65,000
Commercial Real Estate Owner Occupied Loan [Member] | Acquired Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts			0
Recorded principal balance			0
Commercial Real Estate Non Owner Occupied Loan [Member] | Originated Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts	0	0
Recorded principal balance	0	0
Commercial Real Estate Non Owner Occupied Loan [Member] | Acquired Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts			0
Recorded principal balance			0
Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Originated Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts	0	0
Recorded principal balance	0	0
Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Acquired Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts			0
Recorded principal balance			0
Commercial Portfolio Segment [Member] | Originated Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts	0	1
Recorded principal balance	0	65,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts			0
Recorded principal balance			0
Retail Home Equity and Other [Member] | Originated Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts	0	0
Recorded principal balance	0	0
Retail Home Equity and Other [Member] | Acquired Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts			0
Recorded principal balance			0
Retail 1-4 Family Mortgages [Member] | Originated Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts	0	0
Recorded principal balance	0	0
Retail 1-4 Family Mortgages [Member] | Acquired Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts			0
Recorded principal balance			0
Retail Loan [Member] | Originated Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts	0	0
Recorded principal balance	0	0
Retail Loan [Member] | Acquired Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts			0
Recorded principal balance			0
Originated Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts	0	1
Recorded principal balance	0	65,000
Acquired Loan [Member]
Note 4 - Loans and Allowance for Loan Losses (Details) - Loans Modified as Troubled Debt Restructurings within the Previous Twelve Months That Became Over 30 Days Past Due [Line Items]
Number of contracts			0
Recorded principal balance			$0

Recovered_Sheet5

Note 4 - Loans and Allowance for Loan Losses (Details) - Activity for Troubled Debt Restructurings (USD $)	12 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commercial and Industrial [Member] | Originated Loan [Member]
Commercial Loan Portfolio:
Beginning Balance	$1,656,000
Ending Balance	7,026,000	7,026,000
Charge-Offs	-67,000
Payments	-871,000
Transfers to ORE	-21,000
Net Additions/Deletions	6,329,000
Commercial and Industrial [Member] | Acquired Loan [Member]
Commercial Loan Portfolio:
Beginning Balance		0
Ending Balance	1,439,000	1,439,000
Charge-Offs		0
Payments		-2,000
Transfers to ORE		0
Net Additions/Deletions		1,441,000
Commercial and Industrial [Member]
Commercial Loan Portfolio:
Beginning Balance			2,720,000	4,553,000
Ending Balance			1,656,000	2,720,000
Charge-Offs			-35,000	-540,000
Payments			-2,781,000	-2,584,000
Transfers to ORE			-74,000	-96,000
Net Additions/Deletions			1,826,000	1,387,000
Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Originated Loan [Member]
Commercial Loan Portfolio:
Beginning Balance	4,501,000
Ending Balance	2,680,000	2,680,000
Charge-Offs	0
Payments	-4,719,000
Transfers to ORE	0
Net Additions/Deletions	2,898,000
Commercial Vacant Land and Land Development and Residential Construction Loan [Member] | Acquired Loan [Member]
Commercial Loan Portfolio:
Beginning Balance		0
Ending Balance	0	0
Charge-Offs		0
Payments		0
Transfers to ORE		0
Net Additions/Deletions		0
Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Commercial Loan Portfolio:
Beginning Balance			3,071,000	5,100,000
Ending Balance			4,501,000	3,071,000
Charge-Offs			-725,000	-63,000
Payments			-1,596,000	-2,013,000
Transfers to ORE			0	0
Net Additions/Deletions			3,751,000	47,000
Commercial Real Estate Owner Occupied Loan [Member] | Originated Loan [Member]
Commercial Loan Portfolio:
Beginning Balance	1,816,000
Ending Balance	17,160,000	17,160,000
Charge-Offs	-11,000
Payments	-2,343,000
Transfers to ORE	-48,000
Net Additions/Deletions	17,746,000
Commercial Real Estate Owner Occupied Loan [Member] | Acquired Loan [Member]
Commercial Loan Portfolio:
Beginning Balance		0
Ending Balance	1,569,000	1,569,000
Charge-Offs		0
Payments		0
Transfers to ORE		0
Net Additions/Deletions		1,569,000
Commercial Real Estate Owner Occupied Loan [Member]
Commercial Loan Portfolio:
Beginning Balance			4,116,000	6,183,000
Ending Balance			1,816,000	4,116,000
Charge-Offs			-70,000	-426,000
Payments			-2,151,000	-3,443,000
Transfers to ORE			-363,000	-65,000
Net Additions/Deletions			284,000	1,867,000
Commercial Real Estate Non Owner Occupied Loan [Member] | Originated Loan [Member]
Commercial Loan Portfolio:
Beginning Balance	22,311,000
Ending Balance	17,439,000	17,439,000
Charge-Offs	0
Payments	-5,190,000
Transfers to ORE	0
Net Additions/Deletions	318,000
Commercial Real Estate Non Owner Occupied Loan [Member] | Acquired Loan [Member]
Commercial Loan Portfolio:
Beginning Balance		0
Ending Balance	64,000	64,000
Charge-Offs		0
Payments		0
Transfers to ORE		0
Net Additions/Deletions		64,000
Commercial Real Estate Non Owner Occupied Loan [Member]
Commercial Loan Portfolio:
Beginning Balance			37,671,000	12,036,000
Ending Balance			22,312,000	37,671,000
Charge-Offs			-2,537,000	-720,000
Payments			-13,795,000	-2,482,000
Transfers to ORE			-1,153,000	-1,045,000
Net Additions/Deletions			2,126,000	29,882,000
Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Originated Loan [Member]
Commercial Loan Portfolio:
Beginning Balance	2,620,000
Ending Balance	505,000	505,000
Charge-Offs	-420,000
Payments	-1,695,000
Transfers to ORE	0
Net Additions/Deletions	0
Commercial Real Estate Multi Family and Residential Rental Loan [Member] | Acquired Loan [Member]
Commercial Loan Portfolio:
Beginning Balance		0
Ending Balance	381,000	381,000
Charge-Offs		0
Payments		-18,000
Transfers to ORE		0
Net Additions/Deletions		399,000
Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Commercial Loan Portfolio:
Beginning Balance			3,027,000	12,626,000
Ending Balance			2,620,000	3,027,000
Charge-Offs			-15,000	-2,180,000
Payments			-735,000	-7,422,000
Transfers to ORE			0	-186,000
Net Additions/Deletions			343,000	189,000
Retail Home Equity and Other [Member] | Originated Loan [Member]
Commercial Loan Portfolio:
Beginning Balance	0
Ending Balance	0	0
Charge-Offs	0
Payments	0
Transfers to ORE	0
Net Additions/Deletions	0
Retail Home Equity and Other [Member] | Acquired Loan [Member]
Commercial Loan Portfolio:
Beginning Balance		0
Ending Balance	26,000	26,000
Charge-Offs		0
Payments		0
Transfers to ORE		0
Net Additions/Deletions		26,000
Retail Home Equity and Other [Member]
Commercial Loan Portfolio:
Beginning Balance			0	0
Ending Balance			0	0
Charge-Offs			0	0
Payments			0	0
Transfers to ORE			0	0
Net Additions/Deletions			0	0
Retail 1-4 Family Mortgages [Member] | Originated Loan [Member]
Commercial Loan Portfolio:
Beginning Balance	1,987,000
Ending Balance	1,967,000	1,967,000
Charge-Offs	0
Payments	-224,000
Transfers to ORE	0
Net Additions/Deletions	204,000
Retail 1-4 Family Mortgages [Member] | Acquired Loan [Member]
Commercial Loan Portfolio:
Beginning Balance		0
Ending Balance	178,000	178,000
Charge-Offs		0
Payments		0
Transfers to ORE		0
Net Additions/Deletions		178,000
Retail 1-4 Family Mortgages [Member]
Commercial Loan Portfolio:
Beginning Balance			155,000	164,000
Ending Balance			1,987,000	155,000
Charge-Offs			0	0
Payments			-46,000	-9,000
Transfers to ORE			0	0
Net Additions/Deletions			$1,878,000	$0

Recovered_Sheet6

Note 4 - Loans and Allowance for Loan Losses (Details) - Allowance Related to Troubled Debt Restructurings (USD $)	Dec. 31, 2014	Dec. 31, 2013
Commercial:
Allowance for losses, troubled debt restructurings	$5,793,000	$10,399,000
Commercial and Industrial [Member]
Commercial:
Allowance for losses, troubled debt restructurings	16,000	187,000
Commercial Vacant Land and Land Development and Residential Construction Loan [Member]
Commercial:
Allowance for losses, troubled debt restructurings	151,000	798,000
Commercial Real Estate Owner Occupied Loan [Member]
Commercial:
Allowance for losses, troubled debt restructurings	182,000	528,000
Commercial Real Estate Non Owner Occupied Loan [Member]
Commercial:
Allowance for losses, troubled debt restructurings	4,778,000	7,828,000
Commercial Real Estate Multi Family and Residential Rental Loan [Member]
Commercial:
Allowance for losses, troubled debt restructurings	666,000	1,010,000
Commercial Portfolio Segment [Member]
Commercial:
Allowance for losses, troubled debt restructurings	5,793,000	10,351,000
Retail Home Equity and Other [Member]
Commercial:
Allowance for losses, troubled debt restructurings	0	0
Retail 1-4 Family Mortgages [Member]
Commercial:
Allowance for losses, troubled debt restructurings	0	48,000
Retail Loan [Member]
Commercial:
Allowance for losses, troubled debt restructurings	$0	$48,000

Note_5_Premises_and_Equipment_2

Note 5 - Premises and Equipment, Net (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Abstract]
Operating Leases, Future Minimum Payments Due	$1.80
Operating Leases, Future Minimum Payments Due, Next Twelve Months	0.4
Operating Leases, Future Minimum Payments, Due in One to Three Years	0.8
Operating Leases, Future Minimum Payments, Due in Three to Five Years	0.5
Operating Leases, Future Minimum Payments, Due Thereafter	0.1
Depreciation	$2.30	$1.30	$1.50

Note_5_Premises_and_Equipment_3

Note 5 - Premises and Equipment, Net (Details) - Summary of Premises and Equipment (USD $)	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Premises and equipment	$71,962,000	$46,007,000
Less: accumulated depreciation	23,150,000	21,109,000
Total premises and equipment	48,812,000	24,898,000
Land and Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment	16,579,000	8,556,000
Building [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment	38,761,000	24,733,000
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment	$16,622,000	$12,718,000

Note_6_Mortgage_Loan_Servicing2

Note 6 - Mortgage Loan Servicing (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014
Mortgage Loan Servicing [Abstract]
Continuing Involvement with Transferred Financial Assets, Custodial Escrow Balance (in Dollars)	$2.80
Servicing Asset at Fair Value, Amount (in Dollars)	$7.30
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate	7.05%
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Prepayment Speed	12.60%
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Expected Credit Losses	1.01%
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Weighted Average Life	3 years 255 days

Note_6_Mortgage_Loan_Servicing3

Note 6 - Mortgage Loan Servicing (Details) - Mortgage Loans Serviced for Others (USD $)	Dec. 31, 2014
Mortgage loan portfolios serviced for:
Mortgage loans serviced for others	$590,820,000
Federal Home Loan Mortgage Corporation [Member]
Mortgage loan portfolios serviced for:
Mortgage loans serviced for others	589,118,000
Federal Home Loan Bank [Member]
Mortgage loan portfolios serviced for:
Mortgage loans serviced for others	$1,702,000

Note_6_Mortgage_Loan_Servicing4

Note 6 - Mortgage Loan Servicing (Details) - Activity for Capitalized Mortgage Loan Servicing Rights (USD $)	12 Months Ended
	Dec. 31, 2014
Servicing Assets at Fair Value [Line Items]
Balance at January 1, 2014	$0
Additions	575,000
Amortized to expense	-1,252,000
Balance at December 31, 2014	6,712,000
Firstbank Corporation [Member]
Servicing Assets at Fair Value [Line Items]
Additions	$7,389,000

Note_6_Mortgage_Loan_Servicing5

Note 6 - Mortgage Loan Servicing (Details) - Estimated Amortization (USD $)	Dec. 31, 2014
Estimated Amortization [Abstract]
2015	$1,560,000
2016	1,256,000
2017	1,023,000
2018	857,000
2019	722,000
Thereafter	$1,294,000

Note_7_Core_Deposit_Intangible2

Note 7 - Core Deposit Intangible Assets, Net (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Note 7 - Core Deposit Intangible Assets, Net (Details) [Line Items]
Finite-Lived Core Deposits, Gross	$17,500,000
Finite-Lived Intangible Assets, Net	15,624,000	0
Core Deposits [Member]
Note 7 - Core Deposit Intangible Assets, Net (Details) [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	1,900,000
Finite-Lived Intangible Assets, Net	$15,600,000

Note_7_Core_Deposit_Intangible3

Note 7 - Core Deposit Intangible Assets, Net (Details) - Estimated Amortization Expense on Core Deposit Intangible Assets (Core Deposits [Member], USD $)	Dec. 31, 2014
Core Deposits [Member]
Note 7 - Core Deposit Intangible Assets, Net (Details) - Estimated Amortization Expense on Core Deposit Intangible Assets [Line Items]
2015	$2,992,000
2016	2,675,000
2017	2,357,000
2018	2,039,000
2019	1,721,000
Thereafter	$3,839,000

Note_8_Deposits_Details_Summar

Note 8 - Deposits (Details) - Summary of Deposits (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Summary of Deposits [Abstract]
Noninterest-bearing demand (in Dollars)	$558,738,000	$224,580,000
Noninterest-bearing demand	24.50%	20.10%
Noninterest-bearing demand	148.80%
Interest-bearing checking (in Dollars)	413,382,000	197,388,000
Interest-bearing checking	18.20%	17.60%
Interest-bearing checking	109.40%
Money market (in Dollars)	235,587,000	133,369,000
Money market	10.30%	11.90%
Money market	76.60%
Savings (in Dollars)	330,459,000	52,606,000
Savings	14.50%	4.70%
Savings	528.20%
Time, under $100,000 (in Dollars)	181,026,000	43,251,000
Time, under $100,000	8.00%	3.90%
Time, under $100,000	318.50%
Time, $100,000 and over (in Dollars)	382,120,000	254,600,000
Time, $100,000 and over	16.80%	22.80%
Time, $100,000 and over	50.10%
(in Dollars)	2,101,312,000	905,794,000
	92.30%	81.00%
	132.00%
Out-of-area time, under $100,000 (in Dollars)	2,422,000	4,078,000
Out-of-area time, under $100,000	0.10%	0.40%
Out-of-area time, under $100,000	-40.60%
Out-of-area time, $100,000 and over (in Dollars)	173,181,000	209,039,000
Out-of-area time, $100,000 and over	7.60%	18.60%
Out-of-area time, $100,000 and over	-17.20%
(in Dollars)	175,603,000	213,117,000
	7.70%	19.00%
	-17.60%
Total deposits (in Dollars)	$2,276,915,000	$1,118,911,000
Total deposits	100.00%	100.00%
Total deposits	103.50%

Note_8_Deposits_Details_Maturi

Note 8 - Deposits (Details) - Maturity Distribution for Certificate of Deposits (USD $)	Dec. 31, 2014	Dec. 31, 2013
Maturity Distribution for Certificate of Deposits [Abstract]
In one year or less	$368,163,000	$213,454,000
In one to two years	153,346,000	80,138,000
In two to three years	118,919,000	73,271,000
In three to four years	60,953,000	95,979,000
In four to five years	37,368,000	48,126,000
Total certificates of deposit	$738,749,000	$510,968,000

Note_8_Deposits_Details_Certif

Note 8 - Deposits (Details) - Certificates of Deposit with Balances of $100,000 or More (USD $)	Dec. 31, 2014	Dec. 31, 2013
Certificates of Deposit with Balances of $100,000 or More [Abstract]
Up to three months	$75,356,000	$57,469,000
Three months to six months	65,838,000	41,237,000
Six months to twelve months	125,492,000	93,920,000
Over twelve months	288,615,000	271,013,000
Total certificates of deposit	$555,301,000	$463,639,000

Note_9_Securities_Sold_Under_A2

Note 9 - Securities Sold Under Agreements to Repurchase (Details) (Maximum [Member])	12 Months Ended
	Dec. 31, 2014
Maximum [Member]
Note 9 - Securities Sold Under Agreements to Repurchase (Details) [Line Items]
Repurchase Agreement Counterparty, Weighted Average Maturity of Agreements	1 year

Note_9_Securities_Sold_Under_A3

Note 9 - Securities Sold Under Agreements to Repurchase (Details) - Securities Sold Under Agreement To Repurchase (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Securities Sold Under Agreement To Repurchase [Abstract]
Outstanding balance at year-end	$167,569,000	$69,305,000
Weighted average interest rate at year-end	0.11%	0.12%
Average daily balance during the year	105,474,000	65,939,000
Weighted average interest rate during the year	0.12%	0.12%
Maximum daily balance during the year	$178,042,000	$78,960,000

Note_10_Federal_Home_Loan_Bank2

Note 10 - Federal Home Loan Bank Advances (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Disclosure Text Block [Abstract]
Long-term Federal Home Loan Bank Advances (in Dollars)	$54,022,000	$45,000,000
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Interest Rate, Range from	0.62%	1.22%
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Interest Rate, Range to	1.51%	1.51%
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Weighted Average Interest Rate	1.26%	1.34%
Line of Credit Facility, Maximum Borrowing Capacity (in Dollars)	409,500,000
Line of Credit Facility, Remaining Borrowing Capacity (in Dollars)	$355,500,000

Note_10_Federal_Home_Loan_Bank3

Note 10 - Federal Home Loan Bank Advances (Details) - Maturities of Currently Outstanding FHLB Advances (USD $)	Dec. 31, 2014
Maturities over the next five years are:
2015	$6,022,000
2016	3,000,000
2017	45,000,000
2018	0
2019	$0

Note_11_Federal_Income_Taxes_D

Note 11 - Federal Income Taxes (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Jun. 01, 2014
Note 11 - Federal Income Taxes (Details) [Line Items]
Deferred Tax Assets, Valuation Allowance	$450,000	$0
Federal Alternative Minimum Tax Credits	2,800,000
Losses on Capital Investments Acquired [Member]
Note 11 - Federal Income Taxes (Details) [Line Items]
Deferred Tax Assets, Valuation Allowance			500,000
General Business Tax Credit Carryforward [Member]
Note 11 - Federal Income Taxes (Details) [Line Items]
Tax Credit Carryforward, Amount	$600,000

Note_11_Federal_Income_Taxes_D1

Note 11 - Federal Income Taxes (Details) - Consolidated Income Tax Expense (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Consolidated Income Tax Expense [Abstract]
Current expense	$3,359,000	$0	$0
Deferred expense	4,506,000	8,092,000	5,636,000
Tax expense	$7,865,000	$8,092,000	$5,636,000

Note_11_Federal_Income_Taxes_D2

Note 11 - Federal Income Taxes (Details) - Effective Income Tax Rate Reconciliation (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Effective Income Tax Rate Reconciliation [Abstract]
Tax at statutory rate (35%)	$8,819,000	$8,794,000	$6,360,000
Increase (decrease) from
Tax-exempt interest	-621,000	-347,000	-486,000
Bank owned life insurance	-415,000	-465,000	-535,000
Other	82,000	110,000	297,000
Tax expense	$7,865,000	$8,092,000	$5,636,000

Note_11_Federal_Income_Taxes_D3

Note 11 - Federal Income Taxes (Details) - Significant Components of Deferred Tax Assets and Liabilities (USD $)	Dec. 31, 2014	Dec. 31, 2013
Deferred income tax assets
Allowance for loan losses	$7,014,000	$7,987,000
Tax credit carryforwards	3,395,000	1,397,000
Nonaccrual loan interest income	471,000	605,000
Deferred compensation	1,304,000	567,000
Deferred loan fees	445,000	273,000
Fair value write-downs on foreclosed properties	212,000	241,000
Fair value of interest rate swap	89,000	92,000
Losses on capital investments	450,000	0
Stock compensation	521,000	207,000
Net operating loss carryforward	0	4,050,000
Unrealized loss on securities	0	2,908,000
Other	725,000	136,000
	14,626,000	18,463,000
Deferred income tax liabilities
Depreciation	1,217,000	419,000
Prepaid expenses	425,000	192,000
Core deposit intangible	5,386,000	0
Mortgage loan servicing rights	2,349,000	0
Unrealized gain on securities	112,000	0
Other	476,000	98,000
	9,965,000	709,000
Net deferred tax asset before valuation allowance	4,661,000	17,754,000
Valuation allowance	-450,000	0
Total net deferred tax asset	$4,211,000	$17,754,000

Note_12_Stockbased_Compensatio2

Note 12 - Stock-based Compensation (Details) (USD $)	12 Months Ended						3 Months Ended	0 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Jun. 30, 2014	Jun. 01, 2014	Jun. 26, 2014
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Grants in Period (in Shares)		0		0	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in Shares)	277,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in Shares)	6,488	0	0
Employee Stock Option [Member] | Firstbank Corporation [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options (in Dollars)	0.1
Employee Stock Option [Member] | Non-Executive Officers [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	21 days
Employee Stock Option [Member] | Director [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	5 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent	125.00%
Employee Stock Option [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 year
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in Shares)		0	0
Options Granted During 2006, 2007 and 2008 [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	2 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	7 years
Restricted Stock Granted During 2006, 2007 and 2008 [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Restricted Stock Granted in 2012 [Member] | Directors and Certain Employees [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	2 years
Restricted Stock Granted in 2014 [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Stock Options Granted in 2014 [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	2 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	7 years
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent	110.00%
Restricted Stock [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost (in Dollars)							0.2
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	3 years
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options (in Dollars)	2
Stock Option Grants for 50 Shares or Less [Member] | Firstbank Corporation [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 year
Stock Option Grants for Over 50 Shares [Member] | Firstbank Corporation [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	5 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	20.00%
Firstbank Corporation [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in Shares)								282,200
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number (in Shares)								258,400
Maximum [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options (in Dollars)	0.1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value (in Dollars)	0.1
Director [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Stock Issued During Period, Shares, Issued for Services (in Shares)									7,375
Allocated Share-based Compensation Expense (in Dollars)									0.2
Stock Issued for Services, Share-based Compensation Expense Period									6 months
Firstbank Plans [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in Shares)	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value (in Dollars)	1.3

Note_12_Stockbased_Compensatio3

Note 12 - Stock-based Compensation (Details) - Summary of Restricted Stock Activity (Restricted Stock [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted Stock [Member]
Note 12 - Stock-based Compensation (Details) - Summary of Restricted Stock Activity [Line Items]
Nonvested at beginning of year	63,800	66,100	38,650
Nonvested at beginning of year (in Dollars per share)	$14.30	$14.30	$6.20
Granted	101,490	0	66,100
Granted (in Dollars per share)	$20.13		$14.30
Vested	-63,300	0	-38,266
Vested (in Dollars per share)	$14.30		$6.20
Forfeited	-500	-2,300	-384
Forfeited (in Dollars per share)	$14.30	$14.30	$6.20
Nonvested at end of year	101,490	63,800	66,100
Nonvested at end of year (in Dollars per share)	$20.13	$14.30	$14.30

Note_12_Stockbased_Compensatio4

Note 12 - Stock-based Compensation (Details) - Summary Of Stock Option Activity (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary Of Stock Option Activity [Abstract]
Outstanding	60,876	152,896	214,903
Outstanding (in Dollars per share)	$33.11	$26.15	$22.40
Options exercisable at year-end	28,847	60,876	152,896
Options exercisable at year-end (in Dollars per share)	$33.11	$33.11	$26.15
Granted	6,488	0	0
Granted (in Dollars per share)	$22.15
Exercised	-2,845	-51,055	-50,930
Exercised (in Dollars per share)	$17.74	$13.72	$10.83
Forfeited or expired	-29,184	-40,965	-11,077
Forfeited or expired (in Dollars per share)	$34.60	$31.30	$23.77
Outstanding	35,335	60,876	152,896
Outstanding (in Dollars per share)	$31.09	$33.11	$26.15

Note_12_Stockbased_Compensatio5

Note 12 - Stock-based Compensation (Details) - Stock Option Valuation Assumptions (Employee Stock Option [Member])	12 Months Ended
	Dec. 31, 2014
Employee Stock Option [Member]
Note 12 - Stock-based Compensation (Details) - Stock Option Valuation Assumptions [Line Items]
Risk-free interest rate	1.56%
Expected option life (Years)	5 years
Expected stock price volatility	26.00%
Dividend yield	2.50%

Note_12_Stockbased_Compensatio6

Note 12 - Stock-based Compensation (Details) - Summary of Options Outstanding (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit	$6.21	$6.21	$6.21
Exercise price range, upper range limit	$35.88	$40.28	$40.28
Number of Options Outstanding (in Shares)	35,335
Weighted Average Remaining Contractual Life	2 years	1 year 146 days	1 year 328 days
Weighted Average Exercise Price	$31.09
Number of Options Exercisable (in Shares)	28,847
Options Exercisable, Weighted Average Exercise Price	$33.11
Exercise Price Range 1 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit	$6.21
Exercise price range, upper range limit	$8
Number of Options Outstanding (in Shares)	2,700
Weighted Average Remaining Contractual Life	328 days
Weighted Average Exercise Price	$6.21
Number of Options Exercisable (in Shares)	2,700
Options Exercisable, Weighted Average Exercise Price	$6.21
Exercise Price Range 2 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit	$20.01
Exercise price range, upper range limit	$24
Number of Options Outstanding (in Shares)	6,488
Weighted Average Remaining Contractual Life	6 years 328 days
Weighted Average Exercise Price	$22.15
Number of Options Exercisable (in Shares)	0
Exercise Price Range 3 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit	$32.01
Exercise price range, upper range limit	$36
Number of Options Outstanding (in Shares)	26,147
Weighted Average Remaining Contractual Life	328 days
Weighted Average Exercise Price	$35.88
Number of Options Exercisable (in Shares)	26,147
Options Exercisable, Weighted Average Exercise Price	$35.88
Exercise Price Range 4 [Member] | Firstbank Plans [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit	$4
Exercise price range, upper range limit	$8
Number of Options Outstanding (in Shares)	63,590
Weighted Average Remaining Contractual Life	4 years 328 days
Weighted Average Exercise Price	$6.53
Number of Options Exercisable (in Shares)	56,385
Options Exercisable, Weighted Average Exercise Price	$6.70
Exercise Price Range 5 [Member] | Firstbank Plans [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit	$8.01
Exercise price range, upper range limit	$12
Number of Options Outstanding (in Shares)	68,430
Weighted Average Remaining Contractual Life	3 years 255 days
Weighted Average Exercise Price	$13.20
Number of Options Exercisable (in Shares)	68,430
Options Exercisable, Weighted Average Exercise Price	$13.20
Exercise Price Range 6 [Member] | Firstbank Plans [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit	$20.01
Exercise price range, upper range limit	$25
Number of Options Outstanding (in Shares)	85,962
Weighted Average Remaining Contractual Life	1 year 146 days
Weighted Average Exercise Price	$22.43
Number of Options Exercisable (in Shares)	85,962
Options Exercisable, Weighted Average Exercise Price	$22.43
Firstbank Plans [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit	$5.19
Exercise price range, upper range limit	$24.46
Number of Options Outstanding (in Shares)	217,982
Weighted Average Remaining Contractual Life	3 years 36 days
Weighted Average Exercise Price	$14.89
Number of Options Exercisable (in Shares)	210,777
Options Exercisable, Weighted Average Exercise Price	$15.22

Note_12_Stockbased_Compensatio7

Note 12 - Stock-based Compensation (Details) - Summary of Information Related to Options Outstanding (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 12 - Stock-based Compensation (Details) - Summary of Information Related to Options Outstanding [Line Items]
Minimum exercise price	$6.21	$6.21	$6.21
Maximum exercise price	$35.88	$40.28	$40.28
Average remaining option term (Years)	2 years	1 year 146 days	1 year 328 days
Firstbank Plans [Member]
Note 12 - Stock-based Compensation (Details) - Summary of Information Related to Options Outstanding [Line Items]
Minimum exercise price	$5.19
Maximum exercise price	$24.46
Average remaining option term (Years)	3 years 36 days

Note_12_Stockbased_Compensatio8

Note 12 - Stock-based Compensation (Details) - Summary of Stock Option Grants and Exercises (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 12 - Stock-based Compensation (Details) - Summary of Stock Option Grants and Exercises [Line Items]
Cash received from stock option exercises	$282,000	$289,000	$227,000
Mercantile Plans [Member]
Note 12 - Stock-based Compensation (Details) - Summary of Stock Option Grants and Exercises [Line Items]
Aggregate intrinsic value of stock options exercised	11,000	408,000	307,000
Cash received from stock option exercises	50,000	289,000	227,000
Tax benefit realized from stock option exercises	0	0	0
Weighted average per share fair value of stock options granted (in Dollars per share)	$2.72
Firstbank Plans [Member]
Note 12 - Stock-based Compensation (Details) - Summary of Stock Option Grants and Exercises [Line Items]
Aggregate intrinsic value of stock options exercised	333,000
Cash received from stock option exercises	232,000
Tax benefit realized from stock option exercises	$116,000

Note_12_Stockbased_Compensatio9

Note 12 - Stock-based Compensation (Details) - Summary of Stock Option Activity from Grants Issued under Various Firstbank Plans (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Note 12 - Stock-based Compensation (Details) - Summary of Stock Option Activity from Grants Issued under Various Firstbank Plans [Line Items]
Outstanding, shares	35,335	60,876	152,896	214,903
Outstanding, weighted average exercise price	$31.09	$33.11	$26.15	$22.40
Options exercisable at year-end	28,847	60,876	152,896
Options exercisable at year-end	$33.11	$33.11	$26.15
Granted	6,488	0	0
Granted	$22.15
Exercised	-2,845	-51,055	-50,930
Exercised	$17.74	$13.72	$10.83
Forfeited or expired	-29,184	-40,965	-11,077
Forfeited or expired	$34.60	$31.30	$23.77
Firstbank Plans [Member]
Note 12 - Stock-based Compensation (Details) - Summary of Stock Option Activity from Grants Issued under Various Firstbank Plans [Line Items]
Outstanding, shares	217,982	0
Outstanding, weighted average exercise price	$14.89	$0
Options exercisable at year-end	210,777
Options exercisable at year-end	$15.22
Granted	0
Granted	$0
Replaced as part of merger	282,178
Replaced as part of merger	$15.48
Exercised	-27,740
Exercised	$8.34
Forfeited or expired	-36,456
Forfeited or expired	$24.46

Note_13_Related_Parties_Detail

Note 13 - Related Parties (Details) (Directors and Executive Officers [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Directors and Executive Officers [Member]
Note 13 - Related Parties (Details) [Line Items]
Loan Commitments to Related Parties	$15,800,000	$7,800,000
Loans and Leases Receivable, Related Parties	9,002,000	6,884,000	1,418,000
Related Party Deposits and Repurchase Agreements	$16,600,000	$3,900,000

Note_13_Related_Parties_Detail1

Note 13 - Related Parties (Details) - Loans Outstanding to Directors and Executive Officers (Directors and Executive Officers [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Directors and Executive Officers [Member]
Related Party Transaction [Line Items]
Beginning balance	$6,884,000	$1,418,000
New loans	781,000	6,309,000
Repayments	-381,000	-252,000
Adjustments	1,718,000	-591,000
Ending balance	$9,002,000	$6,884,000

Note_14_Commitments_and_Offbal2

Note 14 - Commitments and Off-balance-sheet Risk (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Note 14 - Commitments and Off-balance-sheet Risk (Details) [Line Items]
Reserve or Liability Balance for Financial Instruments with Off-balance Sheet Risk	$0	$0
Mortgage Loans on Real Estate, Minimum Interest Rate in Range	4.00%
Mortgage Loans on Real Estate, Maximum Interest Rate in Range	7.00%
Term Debt Secured by Real Estate Balloon Payment Period	5 years
Term Debt Secured by Non-Real Estate Collateral Maturity Period	5 years
Liabilities for Accreted Fee Collected from Customer	100,000	100,000
Amount of Federal Reserve Requirement	8,400,000	1,500,000
Interest Rate Swap [Member]
Note 14 - Commitments and Off-balance-sheet Risk (Details) [Line Items]
Derivative, Notional Amount	15,400,000
Derivative, Fair Value, Net	($2,900,000)
Minimum [Member]
Note 14 - Commitments and Off-balance-sheet Risk (Details) [Line Items]
Amortization Period for Term Debt Secured by Real Estate	10 years
Interest Rates on Loans Secured by Non-Real Estate Collateral	4.00%
Fees Accreted Into Income During Interest Rate Swap Agreements Term	4 years
Maximum [Member]
Note 14 - Commitments and Off-balance-sheet Risk (Details) [Line Items]
Amortization Period for Term Debt Secured by Real Estate	20 years
Interest Rates on Loans Secured by Non-Real Estate Collateral	7.50%
Fees Accreted Into Income During Interest Rate Swap Agreements Term	15 years

Note_14_Commitments_and_Offbal3

Note 14 - Commitments and Off-balance-sheet Risk (Details) - Exposure to Credit Losses (USD $)	Dec. 31, 2014	Dec. 31, 2013
Note 14 - Commitments and Off-balance-sheet Risk (Details) - Exposure to Credit Losses [Line Items]
Contractual amounts of financial instruments with off-balance sheet risk	$781,748,000	$374,543,000
Unused lines of Credit [Member] | Commercial Portfolio Segment [Member]
Note 14 - Commitments and Off-balance-sheet Risk (Details) - Exposure to Credit Losses [Line Items]
Contractual amounts of financial instruments with off-balance sheet risk	554,856,000	257,937,000
Unused lines of Credit [Member] | Retail 1-4 Family Mortgages [Member]
Note 14 - Commitments and Off-balance-sheet Risk (Details) - Exposure to Credit Losses [Line Items]
Contractual amounts of financial instruments with off-balance sheet risk	60,983,000	23,429,000
Unused lines of Credit [Member] | Consumer Credit Card Financing Receivable [Member]
Note 14 - Commitments and Off-balance-sheet Risk (Details) - Exposure to Credit Losses [Line Items]
Contractual amounts of financial instruments with off-balance sheet risk	11,649,000	9,013,000
Unused lines of Credit [Member] | Consumer Other Financing Receivable [Member]
Note 14 - Commitments and Off-balance-sheet Risk (Details) - Exposure to Credit Losses [Line Items]
Contractual amounts of financial instruments with off-balance sheet risk	8,673,000	5,695,000
Loan Origination Commitments [Member]
Note 14 - Commitments and Off-balance-sheet Risk (Details) - Exposure to Credit Losses [Line Items]
Contractual amounts of financial instruments with off-balance sheet risk	110,126,000	58,799,000
Standby Letters of Credit [Member]
Note 14 - Commitments and Off-balance-sheet Risk (Details) - Exposure to Credit Losses [Line Items]
Contractual amounts of financial instruments with off-balance sheet risk	$35,461,000	$19,670,000

Note_14_Commitments_and_Offbal4

Note 14 - Commitments and Off-balance-sheet Risk (Details) - Instruments Carried at Fair Values (Standby Letters of Credit [Member], USD $)	Dec. 31, 2014	Dec. 31, 2013
Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Standby letters of credit	$35,461,000	$19,670,000
Standby letters of credit	$150,000	$148,000

Note_15_Benefit_Plans_Details

Note 15 - Benefit Plans (Details) (USD $)	0 Months Ended			12 Months Ended
In Millions, except Share data, unless otherwise specified	Jan. 01, 2014	Oct. 01, 2012	Jan. 01, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 15 - Benefit Plans (Details) [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	4.25%	4.00%	3.00%
Defined Contribution Plan, Cost Recognized				$0.90	$0.50	$0.40
Deferred Compensation Liability, Current and Noncurrent				$3.70	$1.60
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in Shares)				1,150	1,098
Stock Purchase Plan [Member]
Note 15 - Benefit Plans (Details) [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance (in Shares)				250,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in Shares)				28,850

Note_16_Hedging_Activities_Det

Note 16 - Hedging Activities (Details) (USD $)	1 Months Ended
	Feb. 29, 2012	Dec. 31, 2014	Dec. 31, 2013
Note 16 - Hedging Activities (Details) [Line Items]
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	$32,000,000	$54,472,000	$32,990,000
Fair Value of Interest Rate Swap Agreement Liability		300,000	300,000
Junior Subordinated Debt [Member] | London Interbank Offered Rate (LIBOR) [Member]
Note 16 - Hedging Activities (Details) [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.18%
Derivative, Notional Amount	$32,000,000

Note_17_Fair_Values_of_Financi2

Note 17 - Fair Values of Financial Instruments (Details) - Fair Value Hierarchy of Financial Instruments (USD $)	Dec. 31, 2014		Dec. 31, 2013
Financial assets
Securities available for sale	$432,912,000	[1]	$131,178,000	[1]
Federal Home Loan Bank stock	13,699,000	[2]	11,961,000	[2]
Federal Home Loan Bank stock	13,699,000	[2]	11,961,000	[2]
Bank owned life insurance	57,861,000		51,377,000
Financial liabilities
Deposits	2,276,915,000		1,118,911,000
Securities sold under agreements to repurchase	167,569,000		69,305,000
Accrued interest payable	12,263,000		7,435,000
Fair Value, Inputs, Level 1 [Member]
Financial assets
Cash	13,261,000		1,464,000
Cash	13,261,000		1,464,000
Fair Value, Inputs, Level 2 [Member]
Financial assets
Cash equivalents	159,477,000		145,501,000
Cash equivalents	159,477,000		145,501,000
Bank owned life insurance	57,861,000		51,377,000
Bank owned life insurance	57,861,000		51,377,000
Accrued interest receivable	8,033,000		3,649,000
Accrued interest receivable	8,033,000		3,649,000
Financial liabilities
Deposits	2,276,915,000		1,118,911,000
Deposits	2,254,749,000		1,120,576,000
Securities sold under agreements to repurchase	167,569,000		69,305,000
Securities sold under agreements to repurchase	167,569,000		69,305,000
Federal Home Loan Bank advances	54,022,000		45,000,000
Federal Home Loan Bank advances	54,720,000		45,139,000
Subordinated debentures	54,472,000		32,990,000
Subordinated debentures	54,508,000		32,974,000
Accrued interest payable	1,942,000		2,041,000
Accrued interest payable	1,942,000		2,041,000
Fair Value, Inputs, Level 3 [Member]
Financial assets
Loans, net	2,069,236,000		1,030,422,000
Loans, net	2,064,140,000		1,027,300,000
Interest Rate Swap [Member]
Financial liabilities
Interest rate swap	253,000	[1]	264,000	[1]
Interest rate swap	$253,000	[1]	$264,000	[1]
[1]	See Note 18 for a description of the fair value hierarchy as well as a disclosure of levels for classes of financial assets and liabilities.
[2]	It is not practical to determine the fair value of FHLB stock due to transferability restrictions.

Note_18_Fair_Values_Measuremen2

Note 18 - Fair Values Measurements (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Disclosure Text Block [Abstract]
Disposal Group, Including Discontinued Operation, Mortgage Loans	$1,574,000	$1,115,000

Note_18_Fair_Values_Measuremen3

Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis (USD $)	Dec. 31, 2014		Dec. 31, 2013
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	$432,912,000	[1]	$131,178,000	[1]
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	0
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			0
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	193,468,000
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			98,477,000
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	0
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			0
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	193,468,000
US Government Agencies Debt Securities [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	193,468,000		98,477,000
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	0
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			0
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	93,561,000
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			13,558,000
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	0
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			0
Collateralized Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	93,561,000
Collateralized Mortgage Backed Securities [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	93,561,000		13,558,000
Municipal General Obligation Bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	0
Municipal General Obligation Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			0
Municipal General Obligation Bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	122,801,000
Municipal General Obligation Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			16,872,000
Municipal General Obligation Bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	10,281,000
Municipal General Obligation Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			0
Municipal General Obligation Bonds [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	133,082,000
Municipal General Obligation Bonds [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	133,082,000		16,872,000
Municipal Revenue Bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	0
Municipal Revenue Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			0
Municipal Revenue Bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	10,873,000
Municipal Revenue Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			916,000
Municipal Revenue Bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	0
Municipal Revenue Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			0
Municipal Revenue Bonds [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	10,873,000
Municipal Revenue Bonds [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	10,873,000		916,000
Other Debt Obligations [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	0
Other Debt Obligations [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	1,928,000
Other Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	0
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	1,928,000
Other Debt Obligations [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities	1,928,000
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			0
Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			1,355,000
Mutual Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			0
Mutual Funds [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Available for sale securities			1,355,000
Fair Value, Inputs, Level 1 [Member] | Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative	0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Assets and Liabilities measured at fair value on recurring basis	0		0
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative	-253,000		-264,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Assets and Liabilities measured at fair value on recurring basis	422,378,000		130,914,000
Fair Value, Inputs, Level 3 [Member] | Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative	0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Assets and Liabilities measured at fair value on recurring basis	10,281,000		0
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative	-253,000		-264,000
Fair Value, Measurements, Recurring [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Assets and Liabilities measured at fair value on recurring basis	$432,659,000		$130,914,000
[1]	See Note 18 for a description of the fair value hierarchy as well as a disclosure of levels for classes of financial assets and liabilities.

Note_18_Fair_Values_Measuremen4

Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Fair Value, Measurements, Nonrecurring [Member], USD $)	Dec. 31, 2014		Dec. 31, 2013
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Impaired loans	$17,097,000	[1]	$23,405,000	[1]
Foreclosed assets	1,995,000	[1]	2,851,000	[1]
Assets and liabilities measured at fair value on a nonrecurring basis	19,092,000		26,256,000
Fair Value, Inputs, Level 1 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Impaired loans	0	[1]	0	[1]
Foreclosed assets	0	[1]	0	[1]
Assets and liabilities measured at fair value on a nonrecurring basis	0		0
Fair Value, Inputs, Level 2 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Impaired loans	0	[1]	0	[1]
Foreclosed assets	0	[1]	0	[1]
Assets and liabilities measured at fair value on a nonrecurring basis	0		0
Fair Value, Inputs, Level 3 [Member]
Note 18 - Fair Values Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis [Line Items]
Impaired loans	17,097,000	[1]	23,405,000	[1]
Foreclosed assets	1,995,000	[1]	2,851,000	[1]
Assets and liabilities measured at fair value on a nonrecurring basis	$19,092,000		$26,256,000
[1]	Represents carrying value and related write-downs for which adjustments are based on the estimated value of the property or other assets.

Note_19_Earnings_Per_Share_Det

Note 19 - Earnings Per Share (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	168,000	55,000	132,000

Note_19_Earnings_Per_Share_Det1

Note 19 - Earnings Per Share (Details) - Earnings Per Share (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basic
Net income attributable to common shares (in Dollars)	$6,293,000	$5,948,000	$1,510,000	$3,580,000	$5,163,000	$3,453,000	$4,016,000	$4,401,000	$17,331,000	$17,033,000	$11,505,000
Net income attributable to common shares (in Dollars)									$17,331,000	$17,033,000	$11,505,000
Weighted average common shares outstanding									13,510,991	8,710,677	8,625,198
Basic earnings per common share (in Dollars per share)	$0.37	$0.35	$0.13	$0.41	$0.59	$0.40	$0.46	$0.51	$1.28	$1.96	$1.33
Add: Dilutive effects of share-based awards									30,913	14,031	224,429
Average shares and dilutive potential common shares									13,541,904	8,724,708	8,849,627
Diluted earnings per common share (in Dollars per share)	$0.37	$0.35	$0.13	$0.41	$0.59	$0.40	$0.46	$0.50	$1.28	$1.95	$1.30

Note_20_Subordinated_Debenture2

Note 20 - Subordinated Debentures (Details) (USD $)	0 Months Ended
In Millions, unless otherwise specified	Jun. 01, 2014	Dec. 31, 2014	Jun. 01, 2014
Debt Disclosure [Abstract]
Number of Business Trusts		5
Business Combination, Debt Assumed, Number of Trusts		4
Fair Value Discount of Subordinated Debentures Related to Assumed Business Trusts at Time of Merger			$15
Amortization of Fair Value Discount Related to Subordinated Debentures of Assumed Business Trusts	$0.70
Amortization Period of Fair Value Discount Related to Subordinated Debentures of Assumed Business Trusts	21 years 6 months

Note_20_Subordinated_Debenture3

Note 20 - Subordinated Debentures (Details) - Business Trusts (USD $)	Dec. 31, 2014	Dec. 31, 2013
Subordinated Borrowing [Line Items]
Preferred securities outstanding	$52,400,000	$32,000,000
Mercantile Bank Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Preferred securities outstanding	32,000,000
Firstbank Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Preferred securities outstanding	10,000,000
Firstbank Capital Trust II [Member]
Subordinated Borrowing [Line Items]
Preferred securities outstanding	10,000,000
Firstbank Capital Trust III [Member]
Subordinated Borrowing [Line Items]
Preferred securities outstanding	7,500,000
Firstbank Capital Trust IV [Member]
Subordinated Borrowing [Line Items]
Preferred securities outstanding	$7,500,000

Note_21_Regulatory_Matters_Det

Note 21 - Regulatory Matters (Details) (USD $)	0 Months Ended					12 Months Ended	0 Months Ended
	Dec. 24, 2014	Sep. 24, 2014	Jun. 25, 2014	29-May-14	Mar. 10, 2014	Dec. 31, 2014	Jan. 15, 2015	Dec. 31, 2013	Dec. 31, 2009	Jan. 30, 2015
Note 21 - Regulatory Matters (Details) [Line Items]
Statutory Accounting Practices, Statutory Amount Available for Dividend Payments without Regulatory Approval						$87,700,000
Common Stock, Dividends, Per Share, Cash Paid (in Dollars per share)	$0.12	$0.12	$0.12	$2	$0.12
Trust Preferred Securities Included in Tier One Capital						52,400,000		32,000,000
Maximum Restricted Core Element Allowed in Tier One Capital, Percent						25.00%
Maximum Level of Consolidated Aggregate Assets Allowing for Inclusion of Trust Preferred Securities in Tier One Capital									15,000,000,000
Preferred Securities of Subsidiary Trust						52,400,000		32,000,000
Subsequent Event [Member]
Note 21 - Regulatory Matters (Details) [Line Items]
Common Stock, Dividends, Per Share, Declared (in Dollars per share)							$0.14
Stock Repurchase Program, Authorized Amount										$20,000,000

Note_21_Regulatory_Matters_Det1

Note 21 - Regulatory Matters (Details) - Actual Capital Levels and Minimum Levels (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Consolidated Entities [Member]
Total capital (to risk weighted assets)
Total capital (to risk weighted assets), actual amount	$334,793	$193,925
Total capital (to risk weighted assets), actual ratio	14.40%	15.90%
Total capital (to risk weighted assets), minimum required for capital adequacy purposes amount	185,553	97,498
Total capital (to risk weighted assets), minimum required for capital adequacy purposes ratio	8.00%	8.00%
Total capital (to risk weighted assets), minimum required to be well capitalized under prompt corrective action regulations amount
Total capital (to risk weighted assets), minimum required to be well capitalized under prompt corrective action regulations ratio
Tier 1 capital (to risk weighted assets)
Tier 1 capital (to risk weighted assets), actual amount	314,752	178,598
Tier 1 capital (to risk weighted assets), actual ratio	13.60%	14.70%
Tier 1 capital (to risk weighted assets), minimum required for capital adequacy purposes amount	92,777	48,749
Tier 1 capital (to risk weighted assets), minimum required for capital adequacy purposes ratio	4.00%	4.00%
Tier 1 capital (to risk weighted assets), minimum required to be well capitalized under prompt corrective action regulations amount
Tier 1 capital (to risk weighted assets), minimum required to be well capitalized under prompt corrective action regulations ratio
Tier 1 capital (to average assets)
Tier 1 capital (to average assets), actual amount	314,752	178,598
Tier 1 capital (to average assets), actual ratio	11.20%	12.50%
Tier 1 capital (to average assets), minimum required for capital adequacy purposes amount	112,949	57,006
Tier 1 capital (to risk average assets), minimum required for capital adequacy purposes ratio	4.00%	4.00%
Tier 1 capital (to risk average assets), minimum required to be well capitalized under prompt corrective action regulations amount
Tier 1 capital (to risk average assets), minimum required to be well capitalized under prompt corrective action regulations ratio
Bank [Member]
Total capital (to risk weighted assets)
Total capital (to risk weighted assets), actual amount	332,749	190,493
Total capital (to risk weighted assets), actual ratio	14.40%	15.70%
Total capital (to risk weighted assets), minimum required for capital adequacy purposes amount	185,309	97,329
Total capital (to risk weighted assets), minimum required for capital adequacy purposes ratio	8.00%	8.00%
Total capital (to risk weighted assets), minimum required to be well capitalized under prompt corrective action regulations amount	231,636	121,662
Total capital (to risk weighted assets), minimum required to be well capitalized under prompt corrective action regulations ratio	10.00%	10.00%
Tier 1 capital (to risk weighted assets)
Tier 1 capital (to risk weighted assets), actual amount	312,708	175,192
Tier 1 capital (to risk weighted assets), actual ratio	13.50%	14.40%
Tier 1 capital (to risk weighted assets), minimum required for capital adequacy purposes amount	92,655	48,665
Tier 1 capital (to risk weighted assets), minimum required for capital adequacy purposes ratio	4.00%	4.00%
Tier 1 capital (to risk weighted assets), minimum required to be well capitalized under prompt corrective action regulations amount	138,982	72,997
Tier 1 capital (to risk weighted assets), minimum required to be well capitalized under prompt corrective action regulations ratio	6.00%	6.00%
Tier 1 capital (to average assets)
Tier 1 capital (to average assets), actual amount	312,708	175,192
Tier 1 capital (to average assets), actual ratio	11.10%	12.30%
Tier 1 capital (to average assets), minimum required for capital adequacy purposes amount	112,856	56,860
Tier 1 capital (to risk average assets), minimum required for capital adequacy purposes ratio	4.00%	4.00%
Tier 1 capital (to risk average assets), minimum required to be well capitalized under prompt corrective action regulations amount	$141,070	$71,075
Tier 1 capital (to risk average assets), minimum required to be well capitalized under prompt corrective action regulations ratio	5.00%	5.00%

Note_22_US_Treasury_Capital_Pu1

Note 22 - U.S. Treasury Capital Purchase Program Participation (Details) (USD $)	0 Months Ended	3 Months Ended		12 Months Ended
	15-May-09	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 22 - U.S. Treasury Capital Purchase Program Participation (Details) [Line Items]
Proceeds from Issuance or Sale of Equity	$21,000,000
Number of Cumulative Perpetual Preferred Shares Received by Treasury under Capital Purchase Program (in Shares)	21,000
Preferred Stock, Redemption Price Per Share (in Dollars per share)	$1,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in Shares)	616,438
Preferred Stock, Par or Stated Value Per Share (in Dollars per share)	$0			$0	$0
Cumulative Dividends Preferred Stock Dividend Rate Percentage for First Five Years	5.00%
Cumulative Dividends Preferred Stock Dividend Rate Percentage for After Five Years	9.00%
Warrant Expiration Period	10 years
Class of Warrant or Right, Exercise Price of Warrants or Rights (in Dollars per share)	$5.11
Reduction from Retained Earnings Resulting from Accelerated Discount on Preferred Stock			600,000
Amortization Period for Accelerated Discount on Preferred Stock			5 years
Payments for Repurchase of Warrants		7,500,000		0	0	7,465,000
Reduction in Shareholders' Equity Resulting from Repurchase of Warrant		7,500,000
Preferred Stock 1 [Member]
Note 22 - U.S. Treasury Capital Purchase Program Participation (Details) [Line Items]
Treasury Stock, Value, Acquired, Par Value Method			$21,000,000

Note_23_Accumulated_Other_Comp1

Note 23 - Accumulated Other Comprehensive Income (Loss) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 23 - Accumulated Other Comprehensive Income (Loss) (Details) [Line Items]
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	$200,000	$5,400,000	$2,400,000
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	7,000	551,000	-723,000
Interest Rate Swap [Member]
Note 23 - Accumulated Other Comprehensive Income (Loss) (Details) [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	($200,000)	($200,000)	($700,000)

Note_24_Quarterly_Financial_Da2

Note 24 - Quarterly Financial Data (Unaudited) (Details) - Quarterly Financial Data (Unaudited) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
2014
Interest Income	$28,147,000	$28,900,000	$18,483,000	$13,588,000	$15,373,000	$14,667,000	$13,992,000	$14,210,000	$89,118,000	$58,242,000	$59,917,000
Net Interest Income	25,173,000	25,989,000	15,552,000	11,064,000	12,695,000	11,994,000	11,312,000	11,455,000	77,778,000	47,456,000	46,701,000
Net Income	$6,293,000	$5,948,000	$1,510,000	$3,580,000	$5,163,000	$3,453,000	$4,016,000	$4,401,000	$17,331,000	$17,033,000	$11,505,000
Basic Earnings per Share (in Dollars per share)	$0.37	$0.35	$0.13	$0.41	$0.59	$0.40	$0.46	$0.51	$1.28	$1.96	$1.33
Diluted Earnings per Share (in Dollars per share)	$0.37	$0.35	$0.13	$0.41	$0.59	$0.40	$0.46	$0.50	$1.28	$1.95	$1.30

Note_25_Mercantile_Bank_Corpor2

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	$33,024,000	$30,165,000
Total assets	2,893,379,000	1,426,966,000
LIABILITIES AND SHAREHOLDERSb EQUITY
Liabilities	2,565,241,000	1,273,641,000
Subordinated debentures	54,472,000	32,990,000		32,000,000
Shareholdersb equity	328,138,000	153,325,000	146,590,000		164,999,000
Total liabilities and shareholdersb 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 SHAREHOLDERSb EQUITY
Liabilities	1,134,000	637,000
Subordinated debentures	54,472,000	32,990,000
Shareholdersb equity	328,138,000	153,325,000
Total liabilities and shareholdersb equity	$383,744,000	$186,952,000

Note_25_Mercantile_Bank_Corpor3

Note 25 - Mercantile Bank Corporation (Parent Company Only) Condensed Financial Statements (Details) - Condensed Statements of Income (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income
Interest and dividends from subsidiaries	$28,147,000	$28,900,000	$18,483,000	$13,588,000	$15,373,000	$14,667,000	$13,992,000	$14,210,000	$89,118,000	$58,242,000	$59,917,000
Expenses
Interest expense									11,340,000	10,786,000	13,216,000
Income before income tax benefit and equity in undistributed net income (loss) of subsidiary									25,196,000	25,125,000	18,171,000
Federal income tax benefit									7,865,000	8,092,000	5,636,000
Net income									17,331,000	17,033,000	12,535,000
Preferred stock dividends and accretion									0	0	1,030,000
Net income attributable to common shares	6,293,000	5,948,000	1,510,000	3,580,000	5,163,000	3,453,000	4,016,000	4,401,000	17,331,000	17,033,000	11,505,000
Comprehensive income									22,920,000	9,810,000	10,857,000
Parent Company [Member]
Income
Interest and dividends from subsidiaries									12,139,000	5,516,000	32,532,000
Total income									12,139,000	5,516,000	32,532,000
Expenses
Interest expense									2,145,000	1,213,000	884,000
Other operating expenses									3,552,000	2,773,000	1,048,000
Total expenses									5,697,000	3,986,000	1,932,000
Income before income tax benefit and equity in undistributed net income (loss) of subsidiary									6,442,000	1,530,000	30,600,000
Federal income tax benefit									-1,758,000	-1,042,000	-665,000
Equity in undistributed net income (loss) of subsidiary									9,131,000	14,461,000	-18,730,000
Net income									17,331,000	17,033,000	12,535,000
Preferred stock dividends and accretion									0	0	1,030,000
Net income attributable to common shares									17,331,000	17,033,000	11,505,000
Comprehensive income									$22,920,000	$9,810,000	$10,857,000

Note_25_Mercantile_Bank_Corpor4

Note 25 - Mercantile Bank Corporation (Parent Company Only) Condensed Financial Statements (Details) - Condensed Statement of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities
Net income	$17,331,000	$17,033,000	$12,535,000
Adjustments to reconcile net income to net cash from operating activities:
Stock-based compensation expense	714,000	473,000	54,000
Change in other assets	1,795,000	8,465,000	-1,805,000
Net cash from operating activities	14,414,000	28,682,000	17,031,000
Cash flows from investing activities
Net cash for investing activities	64,763,000	-12,419,000	66,730,000
Cash flows from financing activities
Repurchase of preferred stock	0	0	-21,000,000
Repurchase of common stock warrant	0	0	-7,465,000
Stock option exercises, net of cashless exercises	282,000	289,000	227,000
Employee stock purchase plan	23,000	19,000	39,000
Dividend reinvestment plan	209,000	33,000	14,000
Stock grants to directors for retainer fees	155,000	0	0
Cash dividends on preferred stock	0	0	-496,000
Cash dividends on common stock	-24,464,000	-3,889,000	-774,000
Net cash for financing activities	-53,404,000	-5,301,000	-24,130,000
Net change in cash and cash equivalents	25,773,000	10,962,000	59,631,000
Parent Company [Member]
Cash flows from operating activities
Net income	17,331,000	17,033,000	12,535,000
Adjustments to reconcile net income to net cash from operating activities:
Equity in undistributed (income) loss of subsidiary	-9,131,000	-14,461,000	18,730,000
Stock-based compensation expense	714,000	473,000	54,000
Change in other assets	-8,163,000	3,244,000	-3,006,000
Change in other liabilities	21,979,000	-708,000	1,073,000
Net cash from operating activities	22,730,000	5,581,000	29,386,000
Cash flows from investing activities
Net capital investment into subsidiaries	0	0	0
Net cash for investing activities	0	0	0
Cash flows from financing activities
Repurchase of preferred stock	0	0	-21,000,000
Repurchase of common stock warrant	0	0	-7,465,000
Stock option exercises, net of cashless exercises	282,000	289,000	227,000
Employee stock purchase plan	23,000	19,000	39,000
Dividend reinvestment plan	209,000	33,000	14,000
Stock grants to directors for retainer fees	155,000	0	0
Cash dividends on preferred stock	0	0	-496,000
Cash dividends on common stock	-24,464,000	-3,889,000	-774,000
Net cash for financing activities	-23,795,000	-3,548,000	-29,455,000
Net change in cash and cash equivalents	-1,065,000	2,033,000	-69,000
Cash and cash equivalents at beginning of period	2,506,000	473,000	542,000
Cash and cash equivalents at end of period	$1,441,000	$2,506,000	$473,000