Mercantile Bank (MBWM) 10-K 28 Feb 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Feb. 01, 2014	Jun. 30, 2013
Document And Entity Information [Abstract]	'	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Trading Symbol	'MBWM	'	'
Entity Registrant Name	'MERCANTILE BANK CORPORATION	'	'
Entity Central Index Key	'0001042729	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Filer Category	'Accelerated Filer	'	'
Entity Common Stock, Shares Outstanding	'	8,739,108	'
Entity Public Float	'	'	$151.50

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Dec. 31, 2013	Dec. 31, 2012
ASSETS	'	'
Cash and due from banks	$17,149,000	$20,302,000
Interest-bearing deposits	6,389,000	10,822,000
Federal funds sold	123,427,000	104,879,000
Total cash and cash equivalents	146,965,000	136,003,000
Securities available for sale	131,178,000	138,314,000
Federal Home Loan Bank stock	11,961,000	11,961,000
Loans	1,053,243,000	1,041,189,000
Allowance for loan losses	-22,821,000	-28,677,000
Loans, net	1,030,422,000	1,012,512,000
Premises and equipment, net	24,898,000	25,919,000
Bank owned life insurance	51,377,000	50,048,000
Accrued interest receivable	3,649,000	3,874,000
Other real estate owned and repossessed assets	2,851,000	6,970,000
Net deferred tax asset	17,754,000	22,015,000
Other assets	5,911,000	15,310,000
Total assets	1,426,966,000	1,422,926,000
Deposits	'	'
Noninterest-bearing	224,580,000	190,241,000
Interest-bearing	894,331,000	944,963,000
Total deposits	1,118,911,000	1,135,204,000
Securities sold under agreements to repurchase	69,305,000	64,765,000
Federal Home Loan Bank advances	45,000,000	35,000,000
Subordinated debentures	32,990,000	32,990,000
Accrued interest and other liabilities	7,435,000	8,377,000
Total liabilities	1,273,641,000	1,276,336,000
Shareholders' equity	'	'
Preferred stock, no par value; 1,000,000 shares authorized; 0 shares outstanding at December 31, 2013 and December 31, 2012	0	0
Common stock, no par value; 20,000,000 shares authorized; 8,739,108 shares outstanding at December 31, 2013 and 8,706,251 shares outstanding at December 31, 2012	162,999,000	166,074,000
Retained earnings (deficit)	-4,101,000	-21,134,000
Accumulated other comprehensive income (loss)	-5,573,000	1,650,000
Total shareholders' equity	153,325,000	146,590,000
Total liabilities and shareholders' equity	$1,426,966,000	$1,422,926,000

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]	'	'
Preferred stock, par value	$0	$0
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$0	$0
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares outstanding	8,739,108	8,706,251

CONSOLIDATED_STATEMENTS_OF_INC

CONSOLIDATED STATEMENTS OF INCOME (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Interest income	'	'	'
Loans, including fees	$52,924,000	$53,898,000	$62,356,000
Securities, taxable	4,134,000	4,383,000	6,685,000
Securities, tax-exempt	951,000	1,415,000	1,805,000
Federal funds sold	212,000	192,000	199,000
Interest-bearing deposits	21,000	29,000	24,000
Total interest income	58,242,000	59,917,000	71,069,000
Interest expense	'	'	'
Deposits	8,912,000	11,137,000	16,384,000
Short-term borrowings	80,000	157,000	405,000
Federal Home Loan Bank advances	533,000	993,000	2,033,000
Subordinated debentures and other borrowings	1,261,000	929,000	1,010,000
Total interest expense	10,786,000	13,216,000	19,832,000
Net interest income	47,456,000	46,701,000	51,237,000
Provision for loan losses	-7,200,000	-3,100,000	6,900,000
Net interest income after provision for loan losses	54,656,000	49,801,000	44,337,000
Noninterest income	'	'	'
Service charges on deposit and sweep accounts	1,532,000	1,523,000	1,640,000
Earnings on bank owned life insurance	1,329,000	1,528,000	1,777,000
Credit and debit card fees	1,063,000	891,000	825,000
Mortgage banking activities	800,000	1,479,000	846,000
Payroll processing	660,000	591,000	515,000
Rental income from other real estate owned	528,000	1,061,000	825,000
Letter of credit fees	370,000	336,000	300,000
Other income	590,000	585,000	554,000
Total noninterest income	6,872,000	7,994,000	7,282,000
Noninterest expense	'	'	'
Salaries and benefits	20,298,000	19,367,000	17,891,000
Occupancy	2,547,000	2,501,000	2,780,000
Furniture and equipment rent, depreciation and maintenance	984,000	1,176,000	1,206,000
Data processing	3,440,000	3,193,000	2,719,000
Merger-related costs	1,246,000	0	0
Advertising	1,113,000	1,167,000	747,000
FDIC insurance costs	793,000	1,200,000	2,843,000
Problem asset costs	595,000	5,862,000	8,290,000
FHLB advance prepayment fees	0	0	213,000
Other expense	5,387,000	5,158,000	4,806,000
Total noninterest expenses	36,403,000	39,624,000	41,495,000
Income before federal income tax expense (benefit)	25,125,000	18,171,000	10,124,000
Federal income tax expense (benefit)	8,092,000	5,636,000	-27,361,000
Net income	17,033,000	12,535,000	37,485,000
Preferred stock dividends and accretion	0	1,030,000	1,343,000
Net income attributable to common shares	$17,033,000	$11,505,000	$36,142,000
Earnings per common share:	'	'	'
Basic	$1.96	$1.33	$4.20
Diluted	$1.95	$1.30	$4.07

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]	'	'	'
Net income	$17,033,000	$12,535,000	$37,485,000
Other comprehensive income (loss):	'	'	'
Unrealized holding gains (losses) on securities available for sale	-11,960,000	-2,184,000	3,851,000
Fair value of interest rate swap	849,000	-1,113,000	0
Other comprehensive income (loss), before tax	-11,111,000	-3,297,000	3,851,000
Tax effect of unrealized holding gains (losses) on securities available for sale	4,186,000	1,229,000	-1,348,000
Tax effect of fair value of interest rate swap	-298,000	390,000	0
Other comprehensive income, tax effect	3,888,000	1,619,000	-1,348,000
Other comprehensive income (loss), net of tax effect	-7,223,000	-1,678,000	2,503,000
Comprehensive income	$9,810,000	$10,857,000	$39,988,000

CONSOLIDATED_STATEMENTS_OF_CHA

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS EQUITY (USD $)	Total	Preferred Stock [Member]	Common Stock [Member]	Common Stock Warrant [Member]	Retained Earnings (Deficit) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Opening Balances at Dec. 31, 2010	$125,936,000	$20,077,000	$172,677,000	$1,138,000	($68,781,000)	$825,000
Preferred stock dividends	-1,089,000	'	'	'	-1,089,000	'
Accretion of preferred stock	0	254,000	'	'	-254,000	'
Employee stock purchase plan (4,726 shares, 2400 shares and 1,098 shares in 2011, 2012 and 2013 respectively)	42,000	'	42,000	'	'	'
Dividend reinvestment plan (644 shares, 934 shares and 1,954 shares in 2011, 2012 and 2013 respectively)	6,000	'	6,000	'	'	'
Stock option exercises (8,800 shares 50,930 shares and 51,055 shares in 2011, 2012, and 2013 respectively)	55,000	'	55,000	'	'	'
Stock-based compensation expense	61,000	'	61,000	'	'	'
Net income (loss)	37,485,000	'	'	'	37,485,000	'
Change in net unrealized gain on securities available for sale, net of reclassifications and tax effect	2,503,000	'	'	'	'	2,503,000
Ending Balances at Dec. 31, 2011	164,999,000	20,331,000	172,841,000	1,138,000	-32,639,000	3,328,000
Repurchase of preferred stock	-21,000,000	-21,000,000	'	'	'	'
Preferred stock dividends	-361,000	'	'	'	-361,000	'
Accretion of preferred stock	0	669,000	'	'	-669,000	'
Repurchase of common stock warrant	-7,465,000	'	-6,327,000	-1,138,000	'	'
Employee stock purchase plan (4,726 shares, 2400 shares and 1,098 shares in 2011, 2012 and 2013 respectively)	39,000	'	39,000	'	'	'
Dividend reinvestment plan (644 shares, 934 shares and 1,954 shares in 2011, 2012 and 2013 respectively)	14,000	'	14,000	'	'	'
Stock option exercises (8,800 shares 50,930 shares and 51,055 shares in 2011, 2012, and 2013 respectively)	551,000	'	551,000	'	'	'
Stock tendered for stock option exercises (19,120 shares and 18,950 shares in 2012 and 2013 respectively)	-324,000	'	-324,000	'	'	'
Stock-based compensation expense	54,000	'	54,000	'	'	'
Cash dividends ($0.09 per common share and $0.45 per common share in 2012 and 2013 respectively)	-774,000	'	-774,000	'	'	'
Net income (loss)	12,535,000	'	'	'	12,535,000	'
Change in net unrealized gain on securities available for sale, net of reclassifications and tax effect	-955,000	'	'	'	'	-955,000
Change in fair value of interest rate swap, net of tax effect	-723,000	'	'	'	'	-723,000
Ending Balances at Dec. 31, 2012	146,590,000	0	166,074,000	0	-21,134,000	1,650,000
Employee stock purchase plan (4,726 shares, 2400 shares and 1,098 shares in 2011, 2012 and 2013 respectively)	19,000	'	19,000	'	'	'
Dividend reinvestment plan (644 shares, 934 shares and 1,954 shares in 2011, 2012 and 2013 respectively)	33,000	'	33,000	'	'	'
Stock option exercises (8,800 shares 50,930 shares and 51,055 shares in 2011, 2012, and 2013 respectively)	700,000	'	700,000	'	'	'
Stock tendered for stock option exercises (19,120 shares and 18,950 shares in 2012 and 2013 respectively)	-411,000	'	-411,000	'	'	'
Stock-based compensation expense	473,000	'	473,000	'	'	'
Cash dividends ($0.09 per common share and $0.45 per common share in 2012 and 2013 respectively)	-3,889,000	'	-3,889,000	'	'	'
Net income (loss)	17,033,000	'	'	'	17,033,000	'
Change in net unrealized gain on securities available for sale, net of reclassifications and tax effect	-7,774,000	'	'	'	'	-7,774,000
Change in fair value of interest rate swap, net of tax effect	551,000	'	'	'	'	551,000
Ending Balances at Dec. 31, 2013	$153,325,000	$0	$162,999,000	'	($4,101,000)	($5,573,000)

CONSOLIDATED_STATEMENTS_OF_CHA1

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS EQUITY (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Shares issued using employee stock purchase plan	1,098	2,400	4,726
Shares issued using dividend reinvestment plan	1,954	934	644
Shares issued using stock option exercises	51,055	50,930	8,800
Number of shares tendered for stock option	18,950	19,120	'
Cash dividends per share	$0.45	$0.09	'
Common Stock [Member]	'	'	'
Shares issued using employee stock purchase plan	1,098	2,400	4,726
Shares issued using dividend reinvestment plan	1,954	934	644
Shares issued using stock option exercises	51,055	50,930	8,800
Number of shares tendered for stock option	18,950	19,120	'
Cash dividends per share	$0.45	$0.09	'

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities	'	'	'
Net income	$17,033,000	$12,535,000	$37,485,000
Adjustments to reconcile net income to net cash from (for) operating activities:	'	'	'
Depreciation and amortization	2,208,000	2,238,000	2,200,000
Provision for loan losses	-7,200,000	-3,100,000	6,900,000
Deferred income tax expense (benefit)	8,092,000	5,636,000	-27,361,000
Stock-based compensation expense	473,000	54,000	61,000
Proceeds from sales of mortgage loans held for sale	51,373,000	83,713,000	50,925,000
Origination of mortgage loans held for sale	-48,321,000	-83,986,000	-50,195,000
Net gain on sales of mortgage loans held for sale	-658,000	-1,247,000	-681,000
Net (gain) loss on sale and valuation write-downs of foreclosed assets	-1,585,000	1,725,000	1,826,000
Earnings on bank owned life insurance	-1,329,000	-1,528,000	-1,777,000
Net change in:	'	'	'
Accrued interest receivable	225,000	529,000	1,539,000
Other assets	8,465,000	-1,805,000	2,771,000
Accrued interest and other liabilities	-269,000	2,257,000	-1,187,000
Net cash from operating activities	28,507,000	17,021,000	22,506,000
Cash flows from investing activities	'	'	'
Purchase of securities available for sale	-49,812,000	-69,956,000	-28,835,000
Proceeds from maturities, calls and repayments of securities available for sale	34,809,000	102,672,000	80,739,000
Proceeds from sales of securities available for sale	10,310,000	0	0
Proceeds from Federal Home Loan Bank stock redemption	0	0	2,384,000
Loan originations and payments, net	-15,298,000	16,237,000	162,928,000
Purchases of premises and equipment, net	-326,000	-571,000	-556,000
Proceeds from sale of foreclosed assets	7,898,000	18,348,000	11,062,000
Net cash from (for) investing activities	-12,419,000	66,730,000	227,722,000
Cash flows from financing activities	'	'	'
Net decrease in time deposits	-23,038,000	-47,257,000	-210,617,000
Net increase in all other deposits	6,745,000	70,386,000	48,860,000
Net increase (decrease) in securities sold under agreements to repurchase	4,540,000	-7,804,000	-44,410,000
Proceeds from Federal Home Loan Bank advances	10,000,000	20,000,000	0
Maturities and prepayments of Federal Home Loan Bank advances	0	-30,000,000	-20,000,000
Maturities of wholesale repurchase agreements	0	0	-10,000,000
Net increase (decrease) in other borrowed money	175,000	10,000	-370,000
Repurchase of preferred stock	0	-21,000,000	0
Repurchase of common stock warrant	0	-7,465,000	0
Proceeds from stock option exercises, net of cashless exercises	289,000	227,000	55,000
Employee stock purchase plan	19,000	39,000	42,000
Dividend reinvestment plan	33,000	14,000	6,000
Payment of cash dividends on preferred stock	0	-496,000	-1,620,000
Payment of cash dividends to common shareholders	-3,889,000	-774,000	0
Net cash for financing activities	-5,126,000	-24,120,000	-238,054,000
Net change in cash and cash equivalents	10,962,000	59,631,000	12,174,000
Cash and cash equivalents at beginning of period	136,003,000	76,372,000	64,198,000
Cash and cash equivalents at end of period	146,965,000	136,003,000	76,372,000
Cash paid during the year for:	'	'	'
Interest	11,059,000	13,741,000	21,742,000
Federal income taxes	0	0	0
Noncash financing and investing activities:	'	'	'
Transfers from loans to foreclosed assets	2,194,000	11,761,000	11,495,000
Preferred stock cash dividend accrued	$0	$0	$134,000

SUMMARY_OF_SIGNIFICANT_ACCOUNT

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	'
	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 Mortgage Company, LLC (“Mortgage Company”), 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 formed a business trust, Mercantile Bank Capital Trust I (“our trust”), in 2004 to issue trust preferred securities. We issued subordinated debentures to our trust in return for the proceeds raised from the issuance of the trust preferred securities. In accordance with accounting guidelines, our trust is not consolidated, but instead we report the subordinated debentures issued to the trust as a liability.
	Nature of Operations: Mercantile was incorporated on July 15, 1997 to establish and own the Bank based in Grand Rapids, Michigan. The Bank is a community-based financial institution, and began operations on December 15, 1997. 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 Grand Rapids, Holland and Lansing areas. 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.
	Mercantile Bank Mortgage Company was formed during 2000. A subsidiary of the Bank, Mercantile Bank Mortgage Company was established to increase the profitability and efficiency of the mortgage loan operations. Mercantile Bank Mortgage Company initiated business on October 24, 2000 via the Bank’s contribution of most of its residential mortgage loan portfolio and participation interests in certain commercial mortgage loans. On the same date, the Bank also transferred its residential mortgage origination function to Mercantile Bank Mortgage Company. On January 1, 2004, Mercantile Bank Mortgage Company was reorganized as Mercantile Bank Mortgage Company, LLC, a limited liability company, which was 99% owned by the Bank and 1% owned by Mercantile Insurance. Mortgage loans originated and held by the mortgage company were serviced by the Bank pursuant to a servicing agreement. Effective January 1, 2013, we dissolved the mortgage company to streamline the administration of our mortgage business. A cash amount commensurate with its 1% ownership interest was distributed to the insurance company. The remaining assets of the mortgage company were assigned to the Bank. We anticipate the business that was formerly conducted by the mortgage company to be performed by the Bank in its ordinary course and do not expect the dissolution to materially impact our financial position or results of operation.
	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 (as applicable). FHLB 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 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 management has 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 $0.5 million and $0.7 million at December 31, 2013 and 2012, 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. Such loans are sold servicing released. Loans held for sale amounted to $1.1 million and $3.5 million as of December 31, 2013 and 2012, respectively. Income from mortgage banking activities includes fees on direct brokered mortgage loans and the net gain on sale of mortgage loans originated for sale.
	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 in to 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 originated for sale, which were insignificant for 2013, 2012 and 2011.
	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.
	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.
	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 Sheet.
	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.
	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. At December 31, 2011, we reversed the full valuation allowance that was initially recorded at December 31, 2009, as described in Note 8.
	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 and our common stock warrant granted to the U.S. Department of Treasury that we repurchased on July 3, 2012, and are determined 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 separate components 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 consisted of interest rate swap agreements that qualified for hedge accounting. In February 2012, we entered into an interest rate swap agreement that qualifies for hedge accounting. However, in June 2011, we simultaneously purchased and sold an interest rate cap, a structure commonly referred to as a “cap corridor”, which does not qualify for hedge accounting. The current outstanding interest rate swap agreement and matured cap corridor are discussed in more detail in Note 13. 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.
	Operating Segment: While we monitor the revenue streams of the various products and services offered, Mercantile manages its business on the basis of one operating segment, banking.
	Adoption of New Accounting Standards: In February 2013, the FASB issued ASU 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income, which is intended to improve the reporting of reclassifications out of accumulated other comprehensive income. The ASU requires an entity to report, either on the face of the income statement or in the notes to the financial statements, the effect of significant reclassifications out of accumulated other comprehensive income on the respective line items in the income statement. We adopted this ASU in the first quarter of 2013.

SECURITIES

SECURITIES	12 Months Ended
	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]	'
SECURITIES	'
	NOTE 2 – 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
	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
	Michigan Strategic Fund bonds		0			0		0			0
	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
	2012
	U.S. Government agency debt obligations	$	78,447,000		$	1,039,000	$	(388,000	)	$	79,098,000
	Mortgage-backed securities		20,182,000			1,814,000		0			21,996,000
	Michigan Strategic Fund bonds		11,255,000			0		0			11,255,000
	Municipal general obligation bonds		21,700,000			1,043,000		0			22,743,000
	Municipal revenue bonds		1,726,000			91,000		0			1,817,000
	Mutual funds		1,354,000			51,000		0			1,405,000
		$	134,664,000		$	4,038,000	$	(388,000	)	$	138,314,000
	Securities with unrealized losses at year-end 2013 and 2012, 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
	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
	Michigan Strategic Fund bonds		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
	2012
	U.S. Government agency debt obligations	$	33,555,000		$	388,000	$	0		$	0	$	33,555,000	$	388,000
	Mortgage-backed securities		0			0		0			0		0		0
	Michigan Strategic Fund bonds		0			0		0			0		0		0
	Municipal general obligation bonds		0			0		0			0		0		0
	Municipal revenue bonds		0			0		0			0		0		0
	Mutual funds		0			0		0			0		0		0
		$	33,555,000		$	388,000	$	0		$	0	$	33,555,000	$	388,000
	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, 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, 2013, 65 debt securities and one mutual fund with a combined fair value totaling $88.4 million have unrealized losses aggregating $10.1 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 the securities, we believe it is more likely than not that we will not be required to sell the securities before recovery and we do expect to recover the entire amortized cost of the securities, no unrealized losses are deemed to be other-than-temporary.
	The amortized cost and fair values of debt securities at December 31, 2013, 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		5.32	%	$	2,444,000	$	2,494,000
	Due from one to five years		6.31			1,018,000		1,047,000
	Due from five to ten years		3.13			32,373,000		31,008,000
	Due after ten years		3.68			89,810,000		81,716,000
	Mortgage-backed securities		5.17			12,456,000		13,558,000
	Mutual funds		2.32			1,386,000		1,355,000
			3.73	%	$	139,487,000	$	131,178,000
	During 2013, Michigan Strategic Fund bonds totaling $10.3 million were sold at par. No securities were sold during 2012 and 2011.
	At year-end 2013 and 2012, the amortized cost of securities issued by the State of Michigan and all its political subdivisions totaled $17.4 million and $23.4 million, with an estimated fair value of $17.8 million and $24.6 million, respectively. Total securities of any other specific issuer, other than the U.S. Government and its agencies, 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 $94.4 million and $83.8 million at December 31, 2013 and 2012, 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.

LOANS_AND_ALLOWANCE_FOR_LOAN_L

LOANS AND ALLOWANCE FOR LOAN LOSSES	12 Months Ended
	Dec. 31, 2013
Receivables [Abstract]	'
LOANS AND ALLOWANCE FOR LOAN LOSSES	'
	NOTE 3 – LOANS AND ALLOWANCE FOR LOAN LOSSES
	Year-end loans disaggregated by class of loan within the loan portfolio segments were as follows:
																Percent
			31-Dec-13						31-Dec-12							Increase
			Balance			%			Balance				%			(Decrease)
	Commercial:
	Commercial and industrial		$	286,373,000			27.2	%	$	285,322,000				27.4	%		0.4	%
	Vacant land, land development, and residential construction			36,741,000			3.5			48,099,000				4.6			(23.6	)
	Real estate – owner occupied			261,877,000			24.9			259,277,000				24.9			1
	Real estate – non-owner occupied			364,066,000			34.6			324,886,000				31.2			12.1
	Real estate – multi-family and residential rental			37,639,000			3.5			50,922,000				4.9			(26.1	)
	Total commercial			986,696,000			93.7			968,506,000				93			1.9
	Retail:
	Home equity and other			35,080,000			3.3			38,917,000				3.7			(9.9	)
	1-4 family mortgages			31,467,000			3			33,766,000				3.3			(6.8	)
	Total retail			66,547,000			6.3			72,683,000				7			(8.4	)
	Total loans		$	1,053,243,000			100	%	$	1,041,189,000				100	%		1.2	%
	Concentrations within the loan portfolio were as follows at year-end:
			2013						2012
						Percentage of							Percentage of
			Balance			Loan Portfolio			Balance				Loan Portfolio
	Commercial real estate loans to lessors of non-residential buildings		$	299,446,000			28.4	%	$	302,723,000				29.1	%
	Year-end nonperforming loans were as follows:
			2013			2012
	Loans past due 90 days or more still accruing interest		$	0		$	0
	Nonaccrual loans			6,718,000			18,970,000
	Total nonperforming loans		$	6,718,000		$	18,970,000
	The recorded principal balance of nonaccrual loans was as follows:
			December 31,			December 31,
			2013			2012
	Commercial:
	Commercial and industrial		$	1,501,000		$	1,677,000
	Vacant land, land development, and residential construction			785,000			2,194,000
	Real estate – owner occupied			389,000			2,087,000
	Real estate – non-owner occupied			168,000			9,010,000
	Real estate – multi-family and residential rental			208,000			2,021,000
	Total commercial			3,051,000			16,989,000
	Retail:
	Home equity and other			788,000			889,000
	1-4 family mortgages			2,879,000			1,092,000
	Total retail			3,667,000			1,981,000
	Total nonaccrual loans		$	6,718,000		$	18,970,000
	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
	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
	An age analysis of past due loans is as follows as of December 31, 2012:
									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
Commercial:
Commercial and industrial		$	80,000		$	0		$	871,000			$	951,000		$	284,371,000		$	285,322,000	$	0
Vacant land, land development, and residential construction			289,000			0			614,000				903,000			47,196,000			48,099,000		0
Real estate – owner occupied			199,000			0			1,337,000				1,536,000			257,741,000			259,277,000		0
Real estate – non-owner occupied			303,000			0			1,123,000				1,426,000			323,460,000			324,886,000		0
Real estate – multi-family and residential rental			0			0			613,000				613,000			50,309,000			50,922,000		0
Total commercial			871,000			0			4,558,000				5,429,000			963,077,000			968,506,000		0
Retail:
Home equity and other			1,000			0			13,000				14,000			38,903,000			38,917,000		0
1- 4 family mortgages			47,000			190,000			437,000				674,000			33,092,000			33,766,000		0
Total retail			48,000			190,000			450,000				688,000			71,995,000			72,683,000		0
Total past due loans		$	919,000		$	190,000		$	5,008,000			$	6,117,000		$	1,035,072,000		$	1,041,189,000	$	0
Impaired 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				$	8,917,000
Impaired 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 with no related allowance recorded were as follows as of December 31, 2012:
										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		$	1,926,000		$	1,617,000				$	3,140,000
Vacant land, land development and residential construction			2,356,000			1,401,000					1,848,000
Real estate – owner occupied			2,368,000			1,557,000					3,139,000
Real estate – non-owner occupied			9,984,000			5,492,000					6,578,000
Real estate – multi-family and residential rental			1,188,000			413,000					756,000
Total commercial			17,822,000			10,480,000					15,461,000
Retail:
Home equity and other			580,000			483,000					579,000
1-4 family mortgages			1,636,000			789,000					730,000
Total retail			2,216,000			1,272,000					1,309,000
Total with no related allowance recorded		$	20,038,000		$	11,752,000				$	16,770,000
Impaired loans with an allowance recorded and total impaired loans were as follows as of December 31, 2012:
												Year-To-Date
		Unpaid										Average
		Contractual			Recorded							Recorded
		Principal			Principal			Related				Principal
		Balance			Balance			Allowance				Balance
With an allowance recorded:
Commercial:
Commercial and industrial		$	3,221,000		$	1,926,000		$	924,000			$	3,110,000
Vacant land, land development and residential construction			2,333,000			2,219,000			1,367,000				3,267,000
Real estate – owner occupied			4,307,000			3,626,000			1,388,000				4,913,000
Real estate – non-owner occupied			33,818,000			32,964,000			11,773,000				25,061,000
Real estate – multi-family and residential rental			4,471,000			3,923,000			1,408,000				7,429,000
Total commercial			48,150,000			44,658,000			16,860,000				43,780,000
Retail:
Home equity and other			423,000			394,000			204,000				286,000
1-4 family mortgages			555,000			475,000			125,000				482,000
Total retail			978,000			869,000			329,000				768,000
Total with an allowance recorded		$	49,128,000		$	45,527,000		$	17,189,000			$	44,548,000
Total impaired loans:
Commercial		$	65,972,000		$	55,138,000		$	16,860,000			$	59,241,000
Retail			3,194,000			2,141,000			329,000				2,077,000
Total impaired loans		$	69,166,000		$	57,279,000		$	17,189,000			$	61,318,000
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 $2.5 million, $2.0 million and $0.2 million during 2013, 2012 and 2011, 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 collections of interest income were recorded during 2012 or 2011. Lost interest income on nonaccrual loans totaled $0.4 million during 2013, $0.8 million during 2012, and $1.4 million during 2011.
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, 2013:
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		$	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
Loans by credit quality indicators were as follows as of December 31, 2012:
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		$	180,314,000		$	6,526,000		$	150,467,000			$	154,127,000		$	24,015,000
Grades 5 – 7			101,832,000			37,697,000			102,988,000				128,041,000			22,082,000
Grades 8 – 9			3,176,000			3,876,000			5,822,000				42,718,000			4,825,000
Total commercial		$	285,322,000		$	48,099,000		$	259,277,000			$	324,886,000		$	50,922,000
Retail credit exposure – credit risk profiled by collateral type:
		Retail			Retail
		Home Equity			1-4 Family
		and Other			Mortgages
Total retail		$	38,917,000		$	33,766,000
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 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			Unallocated				Total
		Loans			Loans
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
The allowance for loan losses and recorded investments in loans for the year-ended December 31, 2011 are as follows:
		Commercial			Retail			Unallocated				Total
		Loans			Loans
Allowance for loan losses:
Beginning balance		$	42,359,000		$	2,972,000		$	37,000			$	45,368,000
Provision for loan losses			4,125,000			2,730,000			45,000				6,900,000
Charge-offs			(16,978,000	)		(2,919,000	)		0				(19,897,000	)
Recoveries			3,925,000			236,000			0				4,161,000
Ending balance		$	33,431,000		$	3,019,000		$	82,000			$	36,532,000
Ending balance: individually evaluated for impairment		$	18,645,000		$	351,000		$	0			$	18,996,000
Ending balance: collectively evaluated for impairment		$	14,786,000		$	2,668,000		$	82,000			$	17,536,000
Total loans:
Ending balance		$	996,905,000		$	75,517,000						$	1,072,422,000
Ending balance: individually evaluated for impairment		$	68,893,000		$	2,085,000						$	70,978,000
Ending balance: collectively evaluated for impairment		$	928,012,000		$	73,432,000						$	1,001,444,000
Loans modified as troubled debt restructurings during 2013 were as follows:
		Number of			Pre-			Post-
		Contracts			Modification			Modification
					Recorded			Recorded
					Principal			Principal
					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 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			Recorded
		Contracts			Principal
					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
Loans modified as troubled debt restructurings during 2012 were as follows:
		Number of			Pre-			Post-
		Contracts			Modification			Modification
					Recorded			Recorded
					Principal			Principal
					Balance			Balance
Commercial:
Commercial and industrial			8		$	1,357,000		$	1,353,000
Vacant land, land development and residential construction			0			0			0
Real estate – owner occupied			6			1,745,000			1,744,000
Real estate – non-owner occupied			15			28,987,000			28,987,000
Real estate – multi-family and residential rental			0			0			0
Total commercial			29			32,089,000			32,084,000
Retail:
Home equity and other			0			0			0
1-4 family mortgages			0			0			0
Total retail			0			0			0
Total			29		$	32,089,000		$	32,084,000
The following loans, modified as troubled debt restructurings within the previous twelve months, became over 30 days past due during the twelve months ended December 31, 2012 (amounts as of period end):
		Number of			Recorded
		Contracts			Principal
					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
Activity for loans categorized as troubled debt restructurings during 2013 is as follows:
		Commercial			Commercial			Commercial				Commercial			Commercial
		and			Vacant Land,			Real Estate -				Real Estate -			Real Estate -
		Industrial			Land Development,			Owner				Non-Owner			Multi-Family
					and Residential			Occupied				Occupied			and Residential
					Construction										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				2,125,000			343,000
Ending Balance		$	1,656,000		$	4,501,000		$	1,816,000			$	22,311,000		$	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			Commercial			Commercial				Commercial			Commercial
		and			Vacant Land,			Real Estate -				Real Estate -			Real Estate -
		Industrial			Land Development,			Owner				Non-Owner			Multi-Family
					and Residential			Occupied				Occupied			and Residential
					Construction										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 Home			Retail
		Equity and			1-4 Family
		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
Activity for loans categorized as troubled debt restructurings during 2011 is as follows:
		Commercial			Commercial			Commercial				Commercial			Commercial
		and			Vacant Land,			Real Estate -				Real Estate -			Real Estate -
		Industrial			Land Development,			Owner				Non-Owner			Multi-Family
					and Residential			Occupied				Occupied			and Residential
					Construction										Rental
Commercial Loan Portfolio:
Beginning Balance		$	850,000		$	10,696,000		$	2,589,000			$	9,330,000		$	7,848,000
Charge-Offs			(850,000	)		(2,429,000	)		0				(1,195,000	)		(21,000	)
Payments			0			(3,137,000	)		(2,477,000	)			(3,614,000	)		(92,000	)
Transfers to ORE			0			(5,130,000	)		0				0			0
Net Additions/Deletions			4,553,000			5,100,000			6,071,000				7,515,000			4,891,000
Ending Balance		$	4,553,000		$	5,100,000		$	6,183,000			$	12,036,000		$	12,626,000
		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			0			164,000
Ending Balance		$	0		$	164,000
The allowance related to loans categorized as troubled debt restructurings was as follows:
		December 31,			December 31,
		2013			2012
Commercial:
Commercial and industrial		$	187,000		$	772,000
Vacant land, land development, and residential construction			798,000			713,000
Real estate – owner occupied			528,000			1,116,000
Real estate – non-owner occupied			7,828,000			9,751,000
Real estate – multi-family and residential rental			1,010,000			745,000
Total commercial			10,351,000			13,097,000
Retail:
Home equity and other			0			0
1-4 family mortgages			0			0
Total retail			0			0
Total related allowance		$	10,351,000		$	13,097,000
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.

PREMISES_AND_EQUIPMENT_NET

PREMISES AND EQUIPMENT, NET	12 Months Ended
	Dec. 31, 2013
Property Plant And Equipment [Abstract]	'
PREMISES AND EQUIPMENT, NET	'
	NOTE 4 – PREMISES AND EQUIPMENT, NET
	Year-end premises and equipment were as follows:
		2013		2012
	Land and improvements	$	8,556,000	$	8,556,000
	Buildings		24,733,000		24,564,000
	Furniture and equipment		12,718,000		12,861,000
			46,007,000		45,981,000
	Less: accumulated depreciation		21,109,000		20,062,000
	Total premises and equipment	$	24,898,000	$	25,919,000
	Depreciation expense totaled $1.3 million in 2013, $1.5 million in 2012, and $1.6 million in 2011.

DEPOSITS

DEPOSITS	12 Months Ended
	Dec. 31, 2013
Banking And Thrift [Abstract]	'
DEPOSITS	'
	NOTE 5 – DEPOSITS
	Deposits at year-end are summarized as follows:
		December 31, 2013					December 31, 2012					Percent
												Increase
		Balance		%			Balance		%			(Decrease)
	Noninterest-bearing demand	$	224,580,000		20.1	%	$	190,241,000		16.8	%		18.1	%
	Interest-bearing checking		197,388,000		17.6			188,057,000		16.5			5
	Money market		133,369,000		11.9			144,479,000		12.7			(7.7	)
	Savings		52,606,000		4.7			56,454,000		5			(6.8	)
	Time, under $100,000		43,251,000		3.9			51,730,000		4.6			(16.4	)
	Time, $100,000 and over		254,600,000		22.8			234,430,000		20.6			8.6
			905,794,000		81			865,391,000		76.2			4.7
	Out-of-area interest-bearing checking		0		NA			21,967,000		1.9			NM
	Out-of-area time, under $100,000		4,078,000		0.4			7,706,000		0.7			(47.1	)
	Out-of-area time, $100,000 and over		209,039,000		18.6			240,140,000		21.2			(13.0	)
			213,117,000		19			269,813,000		23.8			(21.0	)
	Total deposits	$	1,118,911,000		100	%	$	1,135,204,000		100	%		(1.4	%)
	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:
		2013		2012
	In one year or less	$	213,454,000	$	246,630,000
	In one to two years		80,138,000		61,004,000
	In two to three years		73,271,000		67,635,000
	In three to four years		95,979,000		63,894,000
	In four to five years		48,126,000		94,843,000
	Total certificates of deposit	$	510,968,000	$	534,006,000
	The following table depicts the maturity distribution for certificates of deposit with balances of $100,000 or more at year-end:
		2013		2012
	Up to three months	$	57,469,000	$	100,460,000
	Three months to six months		41,237,000		51,762,000
	Six months to twelve months		93,920,000		64,633,000
	Over twelve months		271,013,000		257,715,000
	Total certificates of deposit	$	463,639,000	$	474,570,000

SECURITIES_SOLD_UNDER_AGREEMEN

SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE	12 Months Ended
	Dec. 31, 2013
Banking And Thrift [Abstract]	'
SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE	'
	NOTE 6 – SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE
	Information regarding securities sold under agreements to repurchase at year-end is summarized below:
		2013			2012
	Outstanding balance at year-end	$	69,305,000		$	64,765,000
	Weighted average interest rate at year-end		0.12	%		0.13	%
	Average daily balance during the year	$	65,939,000		$	61,930,000
	Weighted average interest rate during the year		0.12	%		0.25	%
	Maximum daily balance during the year	$	78,960,000		$	81,980,000
	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.

FEDERAL_HOME_LOAN_BANK_ADVANCE

FEDERAL HOME LOAN BANK ADVANCES	12 Months Ended
	Dec. 31, 2013
Banking And Thrift [Abstract]	'
FEDERAL HOME LOAN BANK ADVANCES	'
	NOTE 7 – FEDERAL HOME LOAN BANK ADVANCES
	Federal Home Loan Bank (“FHLB”) advances totaled $45.0 million at December 31, 2013, and mature at varying dates from March 2017 through September 2017, with fixed rates of interest from 1.22% to 1.51% and averaging 1.34%. FHLB advances totaled $35.0 million at December 31, 2012, and mature at varying dates ranging from March 2017 through September 2017, with fixed rates of interest from 1.22% to 1.51% and averaging 1.35%.
	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 collateralized by residential mortgage loans, first mortgage liens on multi-family residential property loans, first mortgage liens on commercial real estate property loans, and substantially all other assets of our Bank, under a blanket lien arrangement. Our borrowing line of credit as of December 31, 2013 totaled $171.9 million, with availability of $116.1 million.
	Maturities over the next five years are:
	2014	$	0
	2015		0
	2016		0
	2017		45,000,000
	2018		0

FEDERAL_INCOME_TAXES

FEDERAL INCOME TAXES	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
FEDERAL INCOME TAXES	'
	NOTE 8 – FEDERAL INCOME TAXES
	The consolidated income tax expense (benefit) is as follows:
		2013			2012			2011
	Current expense (benefit)	$	0		$	0		$	0
	Deferred expense (benefit)		8,092,000			5,636,000			0
	Valuation allowance – change in estimate		0			0			(27,361,000	)
	Tax expense (benefit)	$	8,092,000		$	5,636,000		$	(27,361,000	)
	2011 reflects the reversal of the valuation allowance, which was established in 2009, related to a change in estimate about our ability to realize our net deferred tax assets in future years based on a change in circumstances.
	A reconciliation of the differences between the federal income tax expense (benefit) recorded and the amount computed by applying the federal statutory rate to income before income taxes is as follows:
		2013			2012			2011
	Tax at statutory rate (35%)	$	8,794,000		$	6,360,000		$	3,543,000
	Increase (decrease) from
	Tax-exempt interest		(347,000	)		(486,000	)		(595,000	)
	Bank owned life insurance		(465,000	)		(535,000	)		(622,000	)
	Change in valuation allowance		0			0			(29,640,000	)
	Other		110,000			297,000			(47,000	)
	Tax expense (benefit)	$	8,092,000		$	5,636,000		$	(27,361,000	)
	Significant components of deferred tax assets and liabilities as of December 31, 2013 and 2012 are as follows:
		2013			2012
	Deferred income tax assets
	Allowance for loan losses	$	7,987,000		$	10,037,000
	Net operating loss carryforward		4,050,000			8,235,000
	Unrealized loss on securities		2,908,000			0
	Tax credit carryforwards		1,397,000			1,198,000
	Nonaccrual loan interest income		605,000			892,000
	Deferred compensation		567,000			506,000
	Deferred loan fees		273,000			229,000
	Fair value write-downs on foreclosed properties		241,000			2,124,000
	Fair value of interest rate swap		92,000			390,000
	Contributions carryforwards		0			256,000
	Other		343,000			369,000
			18,463,000			24,236,000
	Deferred income tax liabilities
	Depreciation		419,000			491,000
	Prepaid expenses		192,000			339,000
	Unrealized gain on securities		0			1,278,000
	Other		98,000			113,000
			709,000			2,221,000
	Total net deferred tax asset	$	17,754,000		$	22,015,000
	At December 31, 2013, we had carryforwards of the following tax attributes: gross federal net operating loss of $11.9 million that expires in years 2030 through 2031; general business tax credits of $0.5 million that expire in the years 2028 through 2033; and $0.9 million of federal alternative minimum tax credits with an indefinite life. $0.3 million of the gross federal net operating loss relates to unrealized excess benefits on stock-based compensation for which a tax benefit will be recorded to shareholders’ equity when utilized.
	Accounting guidance requires us to assess whether a valuation allowance should be carried against our deferred tax assets based on the consideration of all available evidence using a “more likely than not” standard. In making such judgments, we consider both positive and negative evidence and analyze changes in near-term market conditions as well as other factors which may impact future operating results. Significant weight is given to evidence that can be objectively verified. During 2011, we returned to pre-tax profitability for four consecutive quarters. Additionally, we experienced lower provision expense, continued declines in nonperforming assets and problem asset administration costs, a higher net interest margin, further strengthening of our regulatory capital ratios, and additional reductions in wholesale funding. Our analysis of the positive and negative evidence led us to conclude that, as of December 31, 2011, it was more likely than not that we had returned to sustainable profitability in amounts sufficient to allow for realization of our deferred tax assets in future years.
	Consequently, in 2011 we reversed the valuation allowance that we had previously determined necessary to carry against our entire net deferred tax asset as of December 31, 2010 and 2009. $27.4 million of our December 31, 2010 valuation allowance was reversed due to this change in judgment and the remaining $2.2 million was reduced due to the tax effects of our 2011 pre-tax income.
	At December 31, 2013, the positive evidence, including that cited above, continues to outweigh any negative evidence and, therefore, we continue to believe it is more likely than not that we will be able to realize all of our deferred tax assets in future years.
	We had no unrecognized tax benefits at any time during 2013 or 2012 and do not anticipate any significant increase in unrecognized tax benefits during 2014. 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 2013 or 2012. Our U.S. federal income tax returns are no longer subject to examination for all years before 2010.

STOCKBASED_COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
STOCK-BASED COMPENSATION	'
	NOTE 9 – 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 Corporation (see Note 23).
	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 are 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 vest after two years. No payments were required from employees for the restricted stock awards. At year-end 2013, there were approximately 384,000 shares authorized for future incentive awards.
	There was no unrecognized compensation cost related to unvested stock options granted under our various stock-based compensation plans, and $0.4 million of total unrecognized compensation cost related to unvested restricted stock granted under our Stock Incentive Plan of 2006 as of December 31, 2013, which is expected to be fully recognized during 2014.
	A summary of restricted stock activity is as follows:
		2013					2012					2011
					Weighted					Weighted					Weighted
					Average					Average					Average
		Shares			Fair Value		Shares			Fair Value		Shares			Fair Value
	Nonvested at beginning of year		66,100		$	14.3		38,650		$	6.2		73,955		$	11.02
	Granted		0			NA		66,100			14.3		0			NA
	Vested		0			NA		(38,266	)		6.2		(28,533	)		17.57
	Forfeited		(2,300	)		14.3		(384	)		6.2		(6,772	)		10.99
	Nonvested at end of year		63,800		$	14.3		66,100		$	14.3		38,650		$	6.2
	A summary of stock option activity is as follows:
		2013					2012					2011
					Weighted					Weighted					Weighted
					Average					Average					Average
					Exercise					Exercise					Exercise
		Shares			Price		Shares			Price		Shares			Price
	Outstanding at beginning of year		152,896		$	26.15		214,903		$	22.4		262,042		$	21.18
	Granted		0			NA		0			NA		0			NA
	Exercised		(51,055	)		13.72		(50,930	)		10.83		(8,800	)		6.21
	Forfeited or expired		(40,965	)		31.3		(11,077	)		23.77		(38,339	)		17.8
	Outstanding at end of year		60,876		$	33.11		152,896		$	26.15		214,903		$	22.4
	Options exercisable at year-end		60,876		$	33.11		152,896		$	26.15		212,643		$	22.57
	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. No stock option grants were made during 2011, 2012 or 2013.
	Options outstanding at year-end 2013 were as follows:
		Outstanding								Exercisable
					Weighted Average		Weighted					Weighted
	Range of				Remaining		Average					Average
	Exercise				Contractual		Exercise					Exercise
	Prices	Number			Life		Price			Number		Price
	$6.21 - $ 8.00		2,700			1.9 Years	$	6.21			2,700	$	6.21
	$16.01 - $ 20.00		2,845			0.9 Years		17.74			2,845		17.74
	$32.01 - $ 36.00		51,863			1.4 Years		34.87			51,863		34.87
	$40.01 - $ 44.00		3,468			0.8 Years		40.28			3,468		40.28
	Outstanding at year end		60,876			1.4 Years	$	33.11			60,876	$	33.11
	Information related to options outstanding at year-end 2013, 2012 and 2011 is as follows:
		2013			2012		2011
	Minimum exercise price	$	6.21		$	6.21	$	6.21
	Maximum exercise price		40.28			40.28		40.28
	Average remaining option term		1.4 Years			1.9 Years		2.8 Years
	Information related to stock option grants and exercises during 2013, 2012 and 2011 follows:
		2013			2012		2011
	Aggregate intrinsic value of stock options exercised	$	408,000		$	307,000	$	26,000
	Cash received from stock option exercises		289,000			227,000		55,000
	Tax benefit realized from stock option exercises		0			0		0
	Weighted average per share fair value of stock options granted		NA			NA		NA
	The aggregate intrinsic value of all stock options outstanding and exercisable at December 31, 2013 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.

RELATED_PARTIES

RELATED PARTIES	12 Months Ended
	Dec. 31, 2013
Related Party Transactions [Abstract]	'
RELATED PARTIES	'
	NOTE 10 – 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 2013 and 2012, the Bank had $7.8 million and $2.9 million in loan commitments to directors and executive officers, of which $6.9 million and $1.4 million were outstanding at year-end 2013 and 2012, respectively, as reflected in the following table. The line item entitled “Adjustments” primarily relates to Board member retirements during 2013 and 2012.
		2013			2012
	Beginning balance	$	1,418,000		$	1,242,000
	New loans		6,309,000			324,000
	Repayments		(252,000	)		(110,000	)
	Adjustments		(591,000	)		(38,000	)
	Ending balance	$	6,884,000		$	1,418,000
	Related party deposits and repurchase agreements totaled $3.9 million and $3.3 million at year-end 2013 and 2012, respectively.

COMMITMENTS_AND_OFFBALANCESHEE

COMMITMENTS AND OFF-BALANCE-SHEET RISK	12 Months Ended
	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]	'
COMMITMENTS AND OFF-BALANCE-SHEET RISK	'
	NOTE 11 – 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, 2013.
	At year-end 2013 and 2012, 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:
		2013		2012
	Commercial unused lines of credit	$	257,937,000	$	222,237,000
	Unused lines of credit secured by 1 – 4 family residential properties		23,429,000		24,250,000
	Credit card unused lines of credit		9,013,000		8,512,000
	Other consumer unused lines of credit		5,695,000		4,613,000
	Commitments to make loans		58,799,000		64,565,000
	Standby letters of credit		19,670,000		10,591,000
	Total commitments	$	374,543,000	$	334,768,000
	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, 2013, the total notional amount of the underlying interest rate swap agreements was $17.9 million, with a net fair value from our commercial loan customers’ perspective of negative $2.3 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 $0.1 million at December 31, 2013 and December 31, 2012.
	The following instruments are considered financial guarantees under current accounting guidance. These instruments are carried at fair value.
		2013				2012
		Contract		Carrying		Contract		Carrying
		Amount		Value		Amount		Value
	Standby letters of credit	$	19,670,000	$	148,000	$	10,591,000	$	218,000
	We were required to have $1.5 million and $1.2 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 2013 and 2012, respectively.

BENEFIT_PLANS

BENEFIT PLANS	12 Months Ended
	Dec. 31, 2013
Compensation And Retirement Disclosure [Abstract]	'
BENEFIT PLANS	'
	NOTE 12 – 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. Effective May 1, 2011 we reinstated our matching contribution to the 401(k) benefit plan at 2% after having suspended matching contributions effective April 1, 2009. We raised the matching contribution to 3% as of January 1, 2012, and then up 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 2013, 2012 and 2011 matching 401(k) contributions charged to expense were $0.5 million, $0.4 million and $0.2 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 are categorized as other liabilities in the Consolidated Balance Sheet, 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 (“Stock Purchase Plan”) is a non-compensatory plan 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 55,000 shares of common stock may be issued under the Stock Purchase Plan; however, the number of shares has been adjusted, and may continue to be adjusted in the future, to reflect stock dividends and other changes in our capitalization. The number of shares issued under the Stock Purchase Plan totaled 1,098 and 2,400 in 2013 and 2012, respectively. As of December 31, 2013, there were 3,942 shares available under the Stock Purchase Plan. As provided for in the merger agreement with Firstbank Corporation, the Stock Purchase Plan was suspended effective August 14, 2013, and is expected to be reinstated after the merger is consummated (see Note 23).

HEDGING_ACTIVITIES

HEDGING ACTIVITIES	12 Months Ended
	Dec. 31, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]	'
HEDGING ACTIVITIES	'
	NOTE 13 – 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 our trust preferred securities. Our $32.0 million of trust preferred securities 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 trust preferred securities. While the trade date of the interest rate swap agreement was in February 2012, the effective date was not until January 2013, with a maturity date in January 2018. 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, 2013 and 2012, the fair value of the interest rate swap agreement was recorded as a liability in the amount of $0.3 million and $1.1 million, respectively.
	In June 2011, we simultaneously purchased and sold an interest rate cap with a correspondent bank, a structure commonly referred to as a “cap corridor.” The cap corridor, which does not qualify for hedge accounting, consisted of us purchasing a $100 million interest rate cap with a strike rate in close proximity to the then-current 30-Day Libor rate and selling a $100 million interest rate cap with a strike rate that is 125 basis points higher than the purchased interest rate cap strike rate. On the settlement date, the present value of the purchased interest rate cap was recorded as an asset, while the present value of the sold interest rate cap was recorded as a liability. At each month end, the recorded balances of the purchased and sold interest rate caps are adjusted to reflect the current present values, with the offsetting entry being recorded to interest income on commercial loans. We recorded a nominal decrease during 2013 to interest income on commercial loans to reflect the net change in present values.
	Payments made or received under the purchased and sold interest rate cap contracts, if any, are also recorded to interest income on commercial loans. No such payments were made or received during 2013. The cap corridor matured in June 2013.

FAIR_VALUES_OF_FINANCIAL_INSTR

FAIR VALUES OF FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
FAIR VALUES OF FINANCIAL INSTRUMENTS	'
	NOTE 14 – 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	2013				2012
			Fair Value	Carrying		Fair		Carrying		Fair
			Hierarchy	Amount		Value		Amount		Value
	Financial assets
	Cash		Level 1	$	1,464	$	1,464	$	1,576	$	1,576
	Cash equivalents		Level 2		145,501		145,501		134,427		134,427
	Securities available for sale		-1		131,178		131,178		138,314		138,314
	Federal Home Loan Bank stock		-2		11,961		11,961		11,961		11,961
	Loans, net		Level 3		1,030,422		1,027,300		1,012,512		1,004,541
	Bank owned life insurance		Level 2		51,377		51,377		50,048		50,048
	Accrued interest receivable		Level 2		3,649		3,649		3,874		3,874
	Financial liabilities
	Deposits		Level 2		1,118,911		1,120,576		1,135,204		1,135,614
	Securities sold under agreements to repurchase		Level 2		69,305		69,305		64,765		64,765
	Federal Home Loan Bank advances		Level 2		45,000		45,139		35,000		35,000
	Subordinated debentures		Level 2		32,990		32,974		32,990		32,943
	Accrued interest payable		Level 2		2,041		2,041		2,314		2,314
	Interest rate swap		-1		264		264		1,113		1,113
	-1	See Note 15 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.

FAIR_VALUE_MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2013
Fair Value Disclosures [Abstract]	'
FAIR VALUE MEASUREMENTS	'
	NOTE 15 – 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, Michigan Strategic Fund bonds and mutual funds. We have no Level 1 or Level 3 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, 2013 and 2012, we determined that the fair value of our mortgage loans held for sale approximated the recorded cost of $1.1 million and $3.5 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, 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.
	The balances of assets and liabilities measured at fair value on a recurring basis as of December 31, 2012 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		$	79,098,000		$	0	$	79,098,000		$	0
	Mortgage-backed securities			21,996,000			0		21,996,000			0
	Michigan Strategic Fund bonds			11,255,000			0		11,255,000			0
	Municipal general obligation bonds			22,743,000			0		22,743,000			0
	Municipal revenue bonds			1,817,000			0		1,817,000			0
	Mutual funds			1,405,000			0		1,405,000			0
	Derivatives
	Interest rate swap agreement			(1,113,000	)		0		(1,113,000	)		0
	Total		$	137,201,000		$	0	$	137,201,000		$	0
	There were no transfers in or out of Level 1, Level 2 or Level 3 during 2012.
	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, 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
	The balances of assets and liabilities measured at fair value on a nonrecurring basis as of December 31, 2012 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)		$	34,406,000		$	0	$	0		$	34,406,000
Foreclosed assets (1)			6,970,000			0		0			6,970,000
Total		$	41,376,000		$	0	$	0		$	41,376,000
-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.

EARNINGS_PER_SHARE

EARNINGS PER SHARE	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
EARNINGS PER SHARE	'
	NOTE 16 – EARNINGS PER SHARE
	The factors used in the earnings per share computation follow:
		2013		2012		2011
	Basic
	Net income attributable to common shares	$	17,033,000	$	11,505,000	$	36,142,000
	Weighted average common shares outstanding		8,710,677		8,625,198		8,602,845
	Basic earnings per common share	$	1.96	$	1.33	$	4.2
	Diluted
	Net income attributable to common shares	$	17,033,000	$	11,505,000	$	36,142,000
	Weighted average common shares outstanding for basic earnings per common share		8,710,677		8,625,198		8,602,845
	Add: Dilutive effects of share-based awards		14,031		224,429		275,335
	Average shares and dilutive potential common shares		8,724,708		8,849,627		8,878,180
	Diluted earnings per common share	$	1.95	$	1.3	$	4.07
	Stock options for approximately 55,000, 132,000 and 167, 000 shares of common stock were antidilutive and were not included in determining dilutive earnings per share in 2013, 2012, and 2011, respectively.

SUBORDINATED_DEBENTURES

SUBORDINATED DEBENTURES	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
SUBORDINATED DEBENTURES	'
	NOTE 17 – SUBORDINATED DEBENTURES
	Our trust, a business trust formed by Mercantile, was organized in 2004 for the purpose of issuing Series A and Series B Preferred Securities. On September 16, 2004, our trust sold the Series A Preferred Securities in a private sale for $16.0 million, and also sold $495,000 of Series A Common Securities to Mercantile. The proceeds of the Series A Preferred Securities and the Series A Common Securities were used by the trust to purchase $16,495,000 of Series A Floating Rate Notes that were issued by Mercantile on September 16, 2004. Mercantile used the proceeds of the Series A Floating Rate Notes to finance the redemption on September 17, 2004 of the $16.0 million of 9.60% Cumulative Preferred Securities issued in 1999 by MBWM Capital Trust I. On December 10, 2004, our trust sold the Series B Preferred Securities in a private sale for $16.0 million, and also sold $495,000 of Series B Common Securities to Mercantile. The proceeds of the Series B Preferred Securities and the Series B Common Securities were used by our trust to purchase $16,495,000 of Series B Floating Rate Notes that were issued by Mercantile on December 10, 2004. Substantially all of the net proceeds of the Series B Floating Rate Notes were contributed to our Bank as capital to provide support for asset growth, fund investments in loans and securities and for general corporate purposes.
	The only significant assets of our trust are the Series A and Series B Floating Rate Notes, and the only significant liabilities of our trust are the Series A and Series B Preferred Securities. The Series A and Series B 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.

REGULATORY_MATTERS

REGULATORY MATTERS	12 Months Ended
	Dec. 31, 2013
Banking And Thrift [Abstract]	'
REGULATORY MATTERS	'
	NOTE 18 – 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 2013 and 2012, 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, 2013 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
	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
	2012
	Total capital (to risk weighted assets)
	Consolidated	$	173,323		14.6	%	$	94,738		8	%	$	NA		NA
	Bank		173,828		14.7			94,629		8			118,286		10	%
	Tier 1 capital (to risk weighted assets)
	Consolidated		158,349		13.4			47,369		4			NA		NA
	Bank		158,871		13.4			47,315		4			70,972		6
	Tier 1 capital (to average assets)
	Consolidated		158,349		11.3			55,995		4			NA		NA
	Bank		158,871		11.4			55,937		4			69,922		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 2013, under the most restrictive of these regulations, our Bank could distribute approximately $31.4 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 October 11, 2012, our Board of Directors declared a cash dividend on our common stock in the amount of $0.09 per share, that was paid on December 10, 2012 to shareholders of record as of November 9, 2012. This represented our first common stock cash dividend since the first quarter of 2010, as in April 2010 we had suspended payments of cash dividends on our common stock. On January 10, 2013, our Board of Directors declared a cash dividend on our common stock in the amount of $0.10 per share that was paid on March 8, 2013 to shareholders of record as of February 8, 2013. On April 11, 2013, our Board of Directors declared a cash dividend on our common stock in the amount of $0.11 per share that was paid on June 10, 2013 to shareholders of record as of May 10, 2013. On July 11, 2013, 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 10, 2013 to shareholders of record as of August 9, 2013. On October 10, 2013, 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 10, 2013 to shareholders of record as of November 8, 2013. 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 will be paid on March 10, 2014 to shareholders of record as of February 10, 2014.
	Our consolidated capital levels as of December 31, 2013 and 2012 include $32.0 million of trust preferred securities issued by the trust in September 2004 and December 2004 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, 2013 and 2012, all $32.0 million of the trust preferred securities were included as Tier 1 capital of Mercantile.

US_TREASURY_CAPITAL_PURCHASE_P

U.S. TREASURY CAPITAL PURCHASE PROGRAM PARTICIPATION	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
U.S. TREASURY CAPITAL PURCHASE PROGRAM PARTICIPATION	'
	NOTE 19 – 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.
	We allocated the $21.0 million in proceeds to the preferred stock and the common stock warrant based on their relative fair values. To determine the fair value of the preferred stock, we used a discounted cash flow model that assumed redemption of the preferred stock at the end of year 5. The discount rate utilized was 12.00% and the estimated fair value was determined to be $15.5 million. The fair value of the common stock warrant was estimated to be $0.9 million using the Black-Scholes option pricing model with the following assumptions: expected dividend yield of 1.00%; risk-free interest rate of 1.99%; expected life of five years; expected volatility of 53.00%; and a weighted average fair value of $3.92 per share.
	The aggregate fair value for both the preferred stock and the common stock warrant was determined to be $16.4 million, with 94.6% of this aggregate attributable to the preferred stock and 5.4% attributable to the common stock warrant. Therefore, the $21.0 million issuance was allocated with $19.9 million being assigned to the preferred stock and $1.1 million being assigned to the common stock warrant.
	The sum of the $1.1 million difference between the $21.0 million face value of the preferred stock and the $19.9 million allocated to it upon issuance and $0.2 million of direct costs associated with the transaction, or $1.3 million, was recorded as a discount on the preferred stock. The $1.3 million discount was being accreted, using the effective interest method, as a reduction in net income available to common shareholders over the five-year period at approximately $0.2 million to $0.3 million per year.
	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.

ACCUMULATED_OTHER_COMPREHENSIV

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	12 Months Ended
	Dec. 31, 2013
Equity [Abstract]	'
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	'
	NOTE 20 – ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)
	At December 31, 2013, accumulated other comprehensive loss, 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 the 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 the interest rate swap of negative $0.7 million. At December 31, 2011, accumulated other comprehensive income, net of tax effects (as applicable), consists of a net unrealized gain on available for sale securities of $3.3 million.

QUARTERLY_FINANCIAL_DATA_UNAUD

QUARTERLY FINANCIAL DATA (UNAUDITED)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]	'
QUARTERLY FINANCIAL DATA (UNAUDITED)	'
	NOTE 21 – QUARTERLY FINANCIAL DATA (UNAUDITED)
						Net Income
						Attributable to
		Interest		Net Interest		Common		Earnings per Share
		Income		Income		Shares		Basic		Diluted
	2013
	First quarter	$	14,209,000	$	11,454,000	$	4,400,000	$	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
	2012
	First quarter	$	15,553,000	$	11,869,000	$	2,552,000	$	0.3	$	0.28
	Second quarter		14,930,000		11,511,000		3,288,000		0.38		0.36
	Third quarter		14,768,000		11,584,000		2,616,000		0.3		0.3
	Fourth quarter		14,666,000		11,737,000		3,049,000		0.35		0.35

MERCANTILE_BANK_CORPORATION_PA

MERCANTILE BANK CORPORATION (PARENT COMPANY ONLY) CONDENSED FINANCIAL STATEMENTS	12 Months Ended
	Dec. 31, 2013
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]	'
MERCANTILE BANK CORPORATION (PARENT COMPANY ONLY) CONDENSED FINANCIAL STATEMENTS	'
	NOTE 22 – MERCANTILE BANK CORPORATION (PARENT COMPANY ONLY) CONDENSED FINANCIAL STATEMENTS
	Following are condensed parent company only financial statements:
	CONDENSED BALANCE SHEETS
		2013			2012
	ASSETS
	Cash and cash equivalents	$	2,506,000		$	473,000
	Investment in bank subsidiary		179,706,000			173,019,000
	Other assets		4,740,000			7,433,000
	Total assets	$	186,952,000		$	180,925,000
	LIABILITIES AND SHAREHOLDERS’ EQUITY
	Liabilities	$	637,000		$	1,345,000
	Subordinated debentures		32,990,000			32,990,000
	Shareholders’ equity		153,325,000			146,590,000
	Total liabilities and shareholders’ equity	$	186,952,000		$	180,925,000
	CONDENSED STATEMENTS OF INCOME
		2013			2012			2011
	Income
	Interest and dividends from subsidiaries	$	5,516,000		$	32,532,000		$	4,974,000
	Total income		5,516,000			32,532,000			4,974,000
	Expenses
	Interest expense		1,213,000			884,000			847,000
	Other operating expenses		2,773,000			1,048,000			1,059,000
	Total expenses		3,986,000			1,932,000			1,906,000
	Income before income tax expense (benefit) and equity in undistributed net income (loss) of subsidiary		1,530,000			30,600,000			3,068,000
	Federal income tax benefit		(1,042,000	)		(665,000	)		(2,272,000	)
	Equity in undistributed net income (loss) of subsidiary		14,461,000			(18,730,000	)		32,145,000
	Net income		17,033,000			12,535,000			37,485,000
	Preferred stock dividends and accretion		0			1,030,000			1,343,000
	Net income attributable to common shares	$	17,033,000		$	11,505,000		$	36,142,000
	CONDENSED STATEMENTS OF CASH FLOWS
		2013			2012			2011
	Cash flows from operating activities
	Net income	$	17,033,000		$	12,535,000		$	37,485,000
	Adjustments to reconcile net income to net cash from (for) operating activities:
	Equity in undistributed (income) loss of subsidiary		(14,461,000	)		18,730,000			(32,145,000	)
	Stock-based compensation expense		473,000			54,000			61,000
	Change in other assets		3,244,000			(3,006,000	)		(3,619,000	)
	Change in other liabilities		(708,000	)		1,073,000			(956,000	)
	Net cash from operating activities		5,581,000			29,386,000			826,000
	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			(21,000,000	)		0
	Repurchase of common stock warrant		0			(7,465,000	)		0
	Stock option exercises, net of cashless exercises		289,000			227,000			55,000
	Employee stock purchase plan		19,000			39,000			42,000
	Dividend reinvestment plan		33,000			14,000			6,000
	Cash dividends on preferred stock		0			(496,000	)		(1,620,000	)
	Cash dividends on common stock		(3,889,000	)		(774,000	)		0
	Net cash for financing activities		(3,548,000	)		(29,455,000	)		(1,517,000	)
	Net change in cash and cash equivalents		2,033,000			(69,000	)		(691,000	)
	Cash and cash equivalents at beginning of period		473,000			542,000			1,233,000
	Cash and cash equivalents at end of period	$	2,506,000		$	473,000		$	542,000

BUSINESS_COMBINATION

BUSINESS COMBINATION	12 Months Ended
	Dec. 31, 2013
Business Combinations [Abstract]	'
BUSINESS COMBINATION	'
	NOTE 23 – BUSINESS COMBINATION
	On August 14, 2013, Mercantile Bank Corporation (“Mercantile”) and Firstbank Corporation (“Firstbank”) entered into an Agreement and Plan of Merger (the “merger agreement”). Under the terms of the merger agreement, Firstbank will be merged with and into Mercantile, with Mercantile as the surviving corporation. Both Mercantile and Firstbank shareholders approved the merger effective December 12, 2013. Approval of the Board of Governors of the Federal Reserve System is required to complete the merger. Approval has not yet been obtained. Mercantile and Firstbank have each agreed to take actions in order to obtain regulatory clearance required to consummate the merger.

SUMMARY_OF_SIGNIFICANT_ACCOUNT1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Principles of Consolidation	'
	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 Mortgage Company, LLC (“Mortgage Company”), 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 formed a business trust, Mercantile Bank Capital Trust I (“our trust”), in 2004 to issue trust preferred securities. We issued subordinated debentures to our trust in return for the proceeds raised from the issuance of the trust preferred securities. In accordance with accounting guidelines, our trust is not consolidated, but instead we report the subordinated debentures issued to the trust as a liability.
Nature of Operations	'
	Nature of Operations: Mercantile was incorporated on July 15, 1997 to establish and own the Bank based in Grand Rapids, Michigan. The Bank is a community-based financial institution, and began operations on December 15, 1997. 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 Grand Rapids, Holland and Lansing areas. 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.
	Mercantile Bank Mortgage Company was formed during 2000. A subsidiary of the Bank, Mercantile Bank Mortgage Company was established to increase the profitability and efficiency of the mortgage loan operations. Mercantile Bank Mortgage Company initiated business on October 24, 2000 via the Bank’s contribution of most of its residential mortgage loan portfolio and participation interests in certain commercial mortgage loans. On the same date, the Bank also transferred its residential mortgage origination function to Mercantile Bank Mortgage Company. On January 1, 2004, Mercantile Bank Mortgage Company was reorganized as Mercantile Bank Mortgage Company, LLC, a limited liability company, which was 99% owned by the Bank and 1% owned by Mercantile Insurance. Mortgage loans originated and held by the mortgage company were serviced by the Bank pursuant to a servicing agreement. Effective January 1, 2013, we dissolved the mortgage company to streamline the administration of our mortgage business. A cash amount commensurate with its 1% ownership interest was distributed to the insurance company. The remaining assets of the mortgage company were assigned to the Bank. We anticipate the business that was formerly conducted by the mortgage company to be performed by the Bank in its ordinary course and do not expect the dissolution to materially impact our financial position or results of operation.
	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	'
	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 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	'
	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 (as applicable). FHLB 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 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: Loans that management has 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 $0.5 million and $0.7 million at December 31, 2013 and 2012, 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	'
	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. Such loans are sold servicing released. Loans held for sale amounted to $1.1 million and $3.5 million as of December 31, 2013 and 2012, respectively. Income from mortgage banking activities includes fees on direct brokered mortgage loans and the net gain on sale of mortgage loans originated for sale.
Troubled Debt Restructurings	'
	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 in to the determination of the allowance for loan losses in the same manner as other defaulted loans.
Allowance for Loan Losses	'
	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: 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 originated for sale, which were insignificant for 2013, 2012 and 2011.
Premises and Equipment	'
	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	'
	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	'
	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.
Bank Owned Life Insurance	'
	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.
Repurchase Agreements	'
	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 Sheet.
Financial Instruments and Loan Commitments	'
	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	'
	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.
Income Taxes	'
	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. At December 31, 2011, we reversed the full valuation allowance that was initially recorded at December 31, 2009, as described in Note 8.
Fair Values of Financial Instruments	'
	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	'
	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 and our common stock warrant granted to the U.S. Department of Treasury that we repurchased on July 3, 2012, and are determined 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: 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 separate components of equity.
Derivatives	'
	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 consisted of interest rate swap agreements that qualified for hedge accounting. In February 2012, we entered into an interest rate swap agreement that qualifies for hedge accounting. However, in June 2011, we simultaneously purchased and sold an interest rate cap, a structure commonly referred to as a “cap corridor”, which does not qualify for hedge accounting. The current outstanding interest rate swap agreement and matured cap corridor are discussed in more detail in Note 13. 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	'
	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.
Operating Segment	'
	Operating Segment: While we monitor the revenue streams of the various products and services offered, Mercantile manages its business on the basis of one operating segment, banking.
Adoption of New Accounting Standards	'
	Adoption of New Accounting Standards: In February 2013, the FASB issued ASU 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income, which is intended to improve the reporting of reclassifications out of accumulated other comprehensive income. The ASU requires an entity to report, either on the face of the income statement or in the notes to the financial statements, the effect of significant reclassifications out of accumulated other comprehensive income on the respective line items in the income statement. We adopted this ASU in the first quarter of 2013.

SECURITIES_Tables

SECURITIES (Tables)	12 Months Ended
	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]	'
Amortized Cost and Fair Value of Available for Sale Securities and Related Pre-tax Gross Unrealized Gains and Losses	'
	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
	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
	Michigan Strategic Fund bonds		0			0		0			0
	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
	2012
	U.S. Government agency debt obligations	$	78,447,000		$	1,039,000	$	(388,000	)	$	79,098,000
	Mortgage-backed securities		20,182,000			1,814,000		0			21,996,000
	Michigan Strategic Fund bonds		11,255,000			0		0			11,255,000
	Municipal general obligation bonds		21,700,000			1,043,000		0			22,743,000
	Municipal revenue bonds		1,726,000			91,000		0			1,817,000
	Mutual funds		1,354,000			51,000		0			1,405,000
		$	134,664,000		$	4,038,000	$	(388,000	)	$	138,314,000
Securities with Unrealized Losses Aggregated by Investment Category and Length of Time	'
	Securities with unrealized losses at year-end 2013 and 2012, 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
	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
	Michigan Strategic Fund bonds		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
	2012
	U.S. Government agency debt obligations	$	33,555,000		$	388,000	$	0		$	0	$	33,555,000	$	388,000
	Mortgage-backed securities		0			0		0			0		0		0
	Michigan Strategic Fund bonds		0			0		0			0		0		0
	Municipal general obligation bonds		0			0		0			0		0		0
	Municipal revenue bonds		0			0		0			0		0		0
	Mutual funds		0			0		0			0		0		0
		$	33,555,000		$	388,000	$	0		$	0	$	33,555,000	$	388,000
Maturities of Securities and Their Weighted Average Yields	'
	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		5.32	%	$	2,444,000	$	2,494,000
	Due from one to five years		6.31			1,018,000		1,047,000
	Due from five to ten years		3.13			32,373,000		31,008,000
	Due after ten years		3.68			89,810,000		81,716,000
	Mortgage-backed securities		5.17			12,456,000		13,558,000
	Mutual funds		2.32			1,386,000		1,355,000
			3.73	%	$	139,487,000	$	131,178,000

LOANS_AND_ALLOWANCE_FOR_LOAN_L1

LOANS AND ALLOWANCE FOR LOAN LOSSES (Tables)	12 Months Ended
	Dec. 31, 2013
Receivables [Abstract]	'
Components of Loan Portfolio Disaggregated by Class of Loan and Percentage Change in Total Loans	'
	Year-end loans disaggregated by class of loan within the loan portfolio segments were as follows:
															Percent
		31-Dec-13						31-Dec-12							Increase
		Balance			%			Balance				%			(Decrease)
	Commercial:
	Commercial and industrial	$	286,373,000			27.2	%	$	285,322,000				27.4	%		0.4	%
	Vacant land, land development, and residential construction		36,741,000			3.5			48,099,000				4.6			(23.6	)
	Real estate – owner occupied		261,877,000			24.9			259,277,000				24.9			1
	Real estate – non-owner occupied		364,066,000			34.6			324,886,000				31.2			12.1
	Real estate – multi-family and residential rental		37,639,000			3.5			50,922,000				4.9			(26.1	)
	Total commercial		986,696,000			93.7			968,506,000				93			1.9
	Retail:
	Home equity and other		35,080,000			3.3			38,917,000				3.7			(9.9	)
	1-4 family mortgages		31,467,000			3			33,766,000				3.3			(6.8	)
	Total retail		66,547,000			6.3			72,683,000				7			(8.4	)
	Total loans	$	1,053,243,000			100	%	$	1,041,189,000				100	%		1.2	%
Concentrations within Loan Portfolio	'
	Concentrations within the loan portfolio were as follows at year-end:
		2013						2012
					Percentage of							Percentage of
		Balance			Loan Portfolio			Balance				Loan Portfolio
	Commercial real estate loans to lessors of non-residential buildings	$	299,446,000			28.4	%	$	302,723,000				29.1	%
Nonperforming Loans	'
	Year-end nonperforming loans were as follows:
		2013			2012
	Loans past due 90 days or more still accruing interest	$	0		$	0
	Nonaccrual loans		6,718,000			18,970,000
	Total nonperforming loans	$	6,718,000		$	18,970,000
Recorded Principal Balance of Nonaccrual Loans	'
	The recorded principal balance of nonaccrual loans was as follows:
		December 31,			December 31,
		2013			2012
	Commercial:
	Commercial and industrial	$	1,501,000		$	1,677,000
	Vacant land, land development, and residential construction		785,000			2,194,000
	Real estate – owner occupied		389,000			2,087,000
	Real estate – non-owner occupied		168,000			9,010,000
	Real estate – multi-family and residential rental		208,000			2,021,000
	Total commercial		3,051,000			16,989,000
	Retail:
	Home equity and other		788,000			889,000
	1-4 family mortgages		2,879,000			1,092,000
	Total retail		3,667,000			1,981,000
	Total nonaccrual loans	$	6,718,000		$	18,970,000
Age Analysis of Past Due Loans	'
	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
	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
	An age analysis of past due loans is as follows as of December 31, 2012:
								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
	Commercial:
	Commercial and industrial	$	80,000		$	0		$	871,000			$	951,000		$	284,371,000		$	285,322,000	$	0
	Vacant land, land development, and residential construction		289,000			0			614,000				903,000			47,196,000			48,099,000		0
	Real estate – owner occupied		199,000			0			1,337,000				1,536,000			257,741,000			259,277,000		0
	Real estate – non-owner occupied		303,000			0			1,123,000				1,426,000			323,460,000			324,886,000		0
	Real estate – multi-family and residential rental		0			0			613,000				613,000			50,309,000			50,922,000		0
	Total commercial		871,000			0			4,558,000				5,429,000			963,077,000			968,506,000		0
	Retail:
	Home equity and other		1,000			0			13,000				14,000			38,903,000			38,917,000		0
	1- 4 family mortgages		47,000			190,000			437,000				674,000			33,092,000			33,766,000		0
	Total retail		48,000			190,000			450,000				688,000			71,995,000			72,683,000		0
	Total past due loans	$	919,000		$	190,000		$	5,008,000			$	6,117,000		$	1,035,072,000		$	1,041,189,000	$	0
Impaired Loans	'
	Impaired 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				$	8,917,000
	Impaired 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 with no related allowance recorded were as follows as of December 31, 2012:
										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	$	1,926,000		$	1,617,000				$	3,140,000
	Vacant land, land development and residential construction		2,356,000			1,401,000					1,848,000
	Real estate – owner occupied		2,368,000			1,557,000					3,139,000
	Real estate – non-owner occupied		9,984,000			5,492,000					6,578,000
	Real estate – multi-family and residential rental		1,188,000			413,000					756,000
	Total commercial		17,822,000			10,480,000					15,461,000
	Retail:
	Home equity and other		580,000			483,000					579,000
	1-4 family mortgages		1,636,000			789,000					730,000
	Total retail		2,216,000			1,272,000					1,309,000
	Total with no related allowance recorded	$	20,038,000		$	11,752,000				$	16,770,000
	Impaired loans with an allowance recorded and total impaired loans were as follows as of December 31, 2012:
												Year-To-Date
	Unpaid										Average
	Contractual			Recorded							Recorded
	Principal			Principal			Related				Principal
	Balance			Balance			Allowance				Balance
With an allowance recorded:
Commercial:
Commercial and industrial	$	3,221,000		$	1,926,000		$	924,000			$	3,110,000
Vacant land, land development and residential construction		2,333,000			2,219,000			1,367,000				3,267,000
Real estate – owner occupied		4,307,000			3,626,000			1,388,000				4,913,000
Real estate – non-owner occupied		33,818,000			32,964,000			11,773,000				25,061,000
Real estate – multi-family and residential rental		4,471,000			3,923,000			1,408,000				7,429,000
Total commercial		48,150,000			44,658,000			16,860,000				43,780,000
Retail:
Home equity and other		423,000			394,000			204,000				286,000
1-4 family mortgages		555,000			475,000			125,000				482,000
Total retail		978,000			869,000			329,000				768,000
Total with an allowance recorded	$	49,128,000		$	45,527,000		$	17,189,000			$	44,548,000
Total impaired loans:
Commercial	$	65,972,000		$	55,138,000		$	16,860,000			$	59,241,000
Retail		3,194,000			2,141,000			329,000				2,077,000
Total impaired loans	$	69,166,000		$	57,279,000		$	17,189,000			$	61,318,000
Loans by Credit Quality Indicators	'
	Loans by credit quality indicators were as follows as of December 31, 2013:
	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	$	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
	Loans by credit quality indicators were as follows as of December 31, 2012:
	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	$	180,314,000		$	6,526,000		$	150,467,000			$	154,127,000		$	24,015,000
	Grades 5 – 7		101,832,000			37,697,000			102,988,000				128,041,000			22,082,000
	Grades 8 – 9		3,176,000			3,876,000			5,822,000				42,718,000			4,825,000
	Total commercial	$	285,322,000		$	48,099,000		$	259,277,000			$	324,886,000		$	50,922,000
	Retail credit exposure – credit risk profiled by collateral type:
		Retail			Retail
		Home Equity			1-4 Family
		and Other			Mortgages
	Total retail	$	38,917,000		$	33,766,000
Activity in Allowance for Loan Losses and Recorded Investments in Loans	'
	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			Unallocated				Total
		Loans			Loans
	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
	The allowance for loan losses and recorded investments in loans for the year-ended December 31, 2011 are as follows:
		Commercial			Retail			Unallocated				Total
		Loans			Loans
	Allowance for loan losses:
	Beginning balance	$	42,359,000		$	2,972,000		$	37,000			$	45,368,000
	Provision for loan losses		4,125,000			2,730,000			45,000				6,900,000
	Charge-offs		(16,978,000	)		(2,919,000	)		0				(19,897,000	)
	Recoveries		3,925,000			236,000			0				4,161,000
	Ending balance	$	33,431,000		$	3,019,000		$	82,000			$	36,532,000
	Ending balance: individually evaluated for impairment	$	18,645,000		$	351,000		$	0			$	18,996,000
	Ending balance: collectively evaluated for impairment	$	14,786,000		$	2,668,000		$	82,000			$	17,536,000
	Total loans:
	Ending balance	$	996,905,000		$	75,517,000						$	1,072,422,000
	Ending balance: individually evaluated for impairment	$	68,893,000		$	2,085,000						$	70,978,000
	Ending balance: collectively evaluated for impairment	$	928,012,000		$	73,432,000						$	1,001,444,000
Loans Modified as Troubled Debt Restructurings	'
	Loans modified as troubled debt restructurings during 2013 were as follows:
		Number of			Pre-			Post-
		Contracts			Modification			Modification
					Recorded			Recorded
					Principal			Principal
					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
	Loans modified as troubled debt restructurings during 2012 were as follows:
		Number of			Pre-			Post-
		Contracts			Modification			Modification
					Recorded			Recorded
					Principal			Principal
					Balance			Balance
	Commercial:
	Commercial and industrial		8		$	1,357,000		$	1,353,000
	Vacant land, land development and residential construction		0			0			0
	Real estate – owner occupied		6			1,745,000			1,744,000
	Real estate – non-owner occupied		15			28,987,000			28,987,000
	Real estate – multi-family and residential rental		0			0			0
	Total commercial		29			32,089,000			32,084,000
	Retail:
	Home equity and other		0			0			0
	1-4 family mortgages		0			0			0
	Total retail		0			0			0
	Total		29		$	32,089,000		$	32,084,000
Loans, Modified as Troubled Debt Restructurings within Previous Twelve Months, that Became Over 30 Days Past Due	'
	The following 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			Recorded
		Contracts			Principal
					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
	The following loans, modified as troubled debt restructurings within the previous twelve months, became over 30 days past due during the twelve months ended December 31, 2012 (amounts as of period end):
		Number of			Recorded
		Contracts			Principal
					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
Activity for Loans Categorized as Troubled Debt Restructurings	'
	Activity for loans categorized as troubled debt restructurings during 2013 is as follows:
		Commercial			Commercial			Commercial				Commercial			Commercial
		and			Vacant Land,			Real Estate -				Real Estate -			Real Estate -
		Industrial			Land Development,			Owner				Non-Owner			Multi-Family
					and Residential			Occupied				Occupied			and Residential
					Construction										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				2,125,000			343,000
	Ending Balance	$	1,656,000		$	4,501,000		$	1,816,000			$	22,311,000		$	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			Commercial			Commercial				Commercial			Commercial
		and			Vacant Land,			Real Estate -				Real Estate -			Real Estate -
		Industrial			Land Development,			Owner				Non-Owner			Multi-Family
					and Residential			Occupied				Occupied			and Residential
					Construction										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 Home			Retail
		Equity and			1-4 Family
		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
	Activity for loans categorized as troubled debt restructurings during 2011 is as follows:
		Commercial			Commercial			Commercial				Commercial			Commercial
		and			Vacant Land,			Real Estate -				Real Estate -			Real Estate -
		Industrial			Land Development,			Owner				Non-Owner			Multi-Family
					and Residential			Occupied				Occupied			and Residential
					Construction										Rental
	Commercial Loan Portfolio:
	Beginning Balance	$	850,000		$	10,696,000		$	2,589,000			$	9,330,000		$	7,848,000
	Charge-Offs		(850,000	)		(2,429,000	)		0				(1,195,000	)		(21,000	)
	Payments		0			(3,137,000	)		(2,477,000	)			(3,614,000	)		(92,000	)
	Transfers to ORE		0			(5,130,000	)		0				0			0
	Net Additions/Deletions		4,553,000			5,100,000			6,071,000				7,515,000			4,891,000
	Ending Balance	$	4,553,000		$	5,100,000		$	6,183,000			$	12,036,000		$	12,626,000
		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		0			164,000
Ending Balance	$	0		$	164,000
Allowance Related to Loans Categorized as Troubled Debt Restructurings	'
	The allowance related to loans categorized as troubled debt restructurings was as follows:
		December 31,			December 31,
		2013			2012
	Commercial:
	Commercial and industrial	$	187,000		$	772,000
	Vacant land, land development, and residential construction		798,000			713,000
	Real estate – owner occupied		528,000			1,116,000
	Real estate – non-owner occupied		7,828,000			9,751,000
	Real estate – multi-family and residential rental		1,010,000			745,000
	Total commercial		10,351,000			13,097,000
	Retail:
	Home equity and other		0			0
	1-4 family mortgages		0			0
	Total retail		0			0
	Total related allowance	$	10,351,000		$	13,097,000

PREMISES_AND_EQUIPMENT_NET_Tab

PREMISES AND EQUIPMENT, NET (Tables)	12 Months Ended
	Dec. 31, 2013
Property Plant And Equipment [Abstract]	'
Summary of Premises and Equipment	'
	Year-end premises and equipment were as follows:
		2013		2012
	Land and improvements	$	8,556,000	$	8,556,000
	Buildings		24,733,000		24,564,000
	Furniture and equipment		12,718,000		12,861,000
			46,007,000		45,981,000
	Less: accumulated depreciation		21,109,000		20,062,000
	Total premises and equipment	$	24,898,000	$	25,919,000

DEPOSITS_Tables

DEPOSITS (Tables)	12 Months Ended
	Dec. 31, 2013
Banking And Thrift [Abstract]	'
Components of Outstanding Balances and Percentage Change in Deposits	'
	Deposits at year-end are summarized as follows:
		December 31, 2013					December 31, 2012					Percent
												Increase
		Balance		%			Balance		%			(Decrease)
	Noninterest-bearing demand	$	224,580,000		20.1	%	$	190,241,000		16.8	%		18.1	%
	Interest-bearing checking		197,388,000		17.6			188,057,000		16.5			5
	Money market		133,369,000		11.9			144,479,000		12.7			(7.7	)
	Savings		52,606,000		4.7			56,454,000		5			(6.8	)
	Time, under $100,000		43,251,000		3.9			51,730,000		4.6			(16.4	)
	Time, $100,000 and over		254,600,000		22.8			234,430,000		20.6			8.6
			905,794,000		81			865,391,000		76.2			4.7
	Out-of-area interest-bearing checking		0		NA			21,967,000		1.9			NM
	Out-of-area time, under $100,000		4,078,000		0.4			7,706,000		0.7			(47.1	)
	Out-of-area time, $100,000 and over		209,039,000		18.6			240,140,000		21.2			(13.0	)
			213,117,000		19			269,813,000		23.8			(21.0	)
	Total deposits	$	1,118,911,000		100	%	$	1,135,204,000		100	%		(1.4	%)
Maturity Distribution for Certificates of Deposit	'
	The following table depicts the maturity distribution for certificates of deposit at year-end:
		2013		2012
	In one year or less	$	213,454,000	$	246,630,000
	In one to two years		80,138,000		61,004,000
	In two to three years		73,271,000		67,635,000
	In three to four years		95,979,000		63,894,000
	In four to five years		48,126,000		94,843,000
	Total certificates of deposit	$	510,968,000	$	534,006,000
Maturity Distribution for Certificates of Deposit of More Than Specified Amount	'
	The following table depicts the maturity distribution for certificates of deposit with balances of $100,000 or more at year-end:
		2013		2012
	Up to three months	$	57,469,000	$	100,460,000
	Three months to six months		41,237,000		51,762,000
	Six months to twelve months		93,920,000		64,633,000
	Over twelve months		271,013,000		257,715,000
	Total certificates of deposit	$	463,639,000	$	474,570,000

SECURITIES_SOLD_UNDER_AGREEMEN1

SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE (Tables)	12 Months Ended
	Dec. 31, 2013
Banking And Thrift [Abstract]	'
Securities Sold Under Agreements to Repurchase	'
	Information regarding securities sold under agreements to repurchase at year-end is summarized below:
		2013			2012
	Outstanding balance at year-end	$	69,305,000		$	64,765,000
	Weighted average interest rate at year-end		0.12	%		0.13	%
	Average daily balance during the year	$	65,939,000		$	61,930,000
	Weighted average interest rate during the year		0.12	%		0.25	%
	Maximum daily balance during the year	$	78,960,000		$	81,980,000

FEDERAL_HOME_LOAN_BANK_ADVANCE1

FEDERAL HOME LOAN BANK ADVANCES (Tables)	12 Months Ended
	Dec. 31, 2013
Banking And Thrift [Abstract]	'
Maturities of Currently Outstanding FHLB Advances	'
	Maturities over the next five years are:
	2014	$	0
	2015		0
	2016		0
	2017		45,000,000
	2018		0

FEDERAL_INCOME_TAXES_Tables

FEDERAL INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Consolidated Income Tax Expense (Benefit)	'
	The consolidated income tax expense (benefit) is as follows:
		2013			2012			2011
	Current expense (benefit)	$	0		$	0		$	0
	Deferred expense (benefit)		8,092,000			5,636,000			0
	Valuation allowance – change in estimate		0			0			(27,361,000	)
	Tax expense (benefit)	$	8,092,000		$	5,636,000		$	(27,361,000	)
Reconciliation of Differences between Federal Income Tax Expense (Benefit) Recorded and Amount Computed by Applying Federal Statutory Rate to Income Before Income Taxes	'
	A reconciliation of the differences between the federal income tax expense (benefit) recorded and the amount computed by applying the federal statutory rate to income before income taxes is as follows:
		2013			2012			2011
	Tax at statutory rate (35%)	$	8,794,000		$	6,360,000		$	3,543,000
	Increase (decrease) from
	Tax-exempt interest		(347,000	)		(486,000	)		(595,000	)
	Bank owned life insurance		(465,000	)		(535,000	)		(622,000	)
	Change in valuation allowance		0			0			(29,640,000	)
	Other		110,000			297,000			(47,000	)
	Tax expense (benefit)	$	8,092,000		$	5,636,000		$	(27,361,000	)
Significant Components of Deferred Tax Assets and Liabilities	'
	Significant components of deferred tax assets and liabilities as of December 31, 2013 and 2012 are as follows:
		2013			2012
	Deferred income tax assets
	Allowance for loan losses	$	7,987,000		$	10,037,000
	Net operating loss carryforward		4,050,000			8,235,000
	Unrealized loss on securities		2,908,000			0
	Tax credit carryforwards		1,397,000			1,198,000
	Nonaccrual loan interest income		605,000			892,000
	Deferred compensation		567,000			506,000
	Deferred loan fees		273,000			229,000
	Fair value write-downs on foreclosed properties		241,000			2,124,000
	Fair value of interest rate swap		92,000			390,000
	Contributions carryforwards		0			256,000
	Other		343,000			369,000
			18,463,000			24,236,000
	Deferred income tax liabilities
	Depreciation		419,000			491,000
	Prepaid expenses		192,000			339,000
	Unrealized gain on securities		0			1,278,000
	Other		98,000			113,000
			709,000			2,221,000
	Total net deferred tax asset	$	17,754,000		$	22,015,000

STOCKBASED_COMPENSATION_Tables

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Summary of Restricted Stock Activity	'
	A summary of restricted stock activity is as follows:
		2013					2012					2011
					Weighted					Weighted					Weighted
					Average					Average					Average
		Shares			Fair Value		Shares			Fair Value		Shares			Fair Value
	Nonvested at beginning of year		66,100		$	14.3		38,650		$	6.2		73,955		$	11.02
	Granted		0			NA		66,100			14.3		0			NA
	Vested		0			NA		(38,266	)		6.2		(28,533	)		17.57
	Forfeited		(2,300	)		14.3		(384	)		6.2		(6,772	)		10.99
	Nonvested at end of year		63,800		$	14.3		66,100		$	14.3		38,650		$	6.2
Summary of Stock Option Activity	'
	A summary of stock option activity is as follows:
		2013					2012					2011
					Weighted					Weighted					Weighted
					Average					Average					Average
					Exercise					Exercise					Exercise
		Shares			Price		Shares			Price		Shares			Price
	Outstanding at beginning of year		152,896		$	26.15		214,903		$	22.4		262,042		$	21.18
	Granted		0			NA		0			NA		0			NA
	Exercised		(51,055	)		13.72		(50,930	)		10.83		(8,800	)		6.21
	Forfeited or expired		(40,965	)		31.3		(11,077	)		23.77		(38,339	)		17.8
	Outstanding at end of year		60,876		$	33.11		152,896		$	26.15		214,903		$	22.4
	Options exercisable at year-end		60,876		$	33.11		152,896		$	26.15		212,643		$	22.57
Summary of Options Outstanding	'
	Options outstanding at year-end 2013 were as follows:
		Outstanding								Exercisable
					Weighted Average		Weighted					Weighted
	Range of				Remaining		Average					Average
	Exercise				Contractual		Exercise					Exercise
	Prices	Number			Life		Price			Number		Price
	$6.21 - $ 8.00		2,700			1.9 Years	$	6.21			2,700	$	6.21
	$16.01 - $ 20.00		2,845			0.9 Years		17.74			2,845		17.74
	$32.01 - $ 36.00		51,863			1.4 Years		34.87			51,863		34.87
	$40.01 - $ 44.00		3,468			0.8 Years		40.28			3,468		40.28
	Outstanding at year end		60,876			1.4 Years	$	33.11			60,876	$	33.11
Summary of Information Related to Options Outstanding	'
	Information related to options outstanding at year-end 2013, 2012 and 2011 is as follows:
		2013			2012		2011
	Minimum exercise price	$	6.21		$	6.21	$	6.21
	Maximum exercise price		40.28			40.28		40.28
	Average remaining option term		1.4 Years			1.9 Years		2.8 Years
Summary of Stock Option Grants and Exercises	'
	Information related to stock option grants and exercises during 2013, 2012 and 2011 follows:
		2013			2012		2011
	Aggregate intrinsic value of stock options exercised	$	408,000		$	307,000	$	26,000
	Cash received from stock option exercises		289,000			227,000		55,000
	Tax benefit realized from stock option exercises		0			0		0
	Weighted average per share fair value of stock options granted		NA			NA		NA

RELATED_PARTIES_Tables

RELATED PARTIES (Tables)	12 Months Ended
	Dec. 31, 2013
Related Party Transactions [Abstract]	'
Loans Outstanding to Directors and Executive Officers at Beginning of Period and End of Period, Including Activity During Period	'
		2013			2012
	Beginning balance	$	1,418,000		$	1,242,000
	New loans		6,309,000			324,000
	Repayments		(252,000	)		(110,000	)
	Adjustments		(591,000	)		(38,000	)
	Ending balance	$	6,884,000		$	1,418,000

COMMITMENTS_AND_OFFBALANCESHEE1

COMMITMENTS AND OFF-BALANCE-SHEET RISK (Tables)	12 Months Ended
	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Maximum Exposure to Credit Losses for Loan Commitments and Standby Letters of Credit Outstanding	'
	Our maximum exposure to credit losses for loan commitments and standby letters of credit outstanding at year-end was as follows:
		2013		2012
	Commercial unused lines of credit	$	257,937,000	$	222,237,000
	Unused lines of credit secured by 1 – 4 family residential properties		23,429,000		24,250,000
	Credit card unused lines of credit		9,013,000		8,512,000
	Other consumer unused lines of credit		5,695,000		4,613,000
	Commitments to make loans		58,799,000		64,565,000
	Standby letters of credit		19,670,000		10,591,000
	Total commitments	$	374,543,000	$	334,768,000
Instruments Carried at Fair Value	'
	The following instruments are considered financial guarantees under current accounting guidance. These instruments are carried at fair value.
		2013				2012
		Contract		Carrying		Contract		Carrying
		Amount		Value		Amount		Value
	Standby letters of credit	$	19,670,000	$	148,000	$	10,591,000	$	218,000

FAIR_VALUES_OF_FINANCIAL_INSTR1

FAIR VALUES OF FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Carrying Amount, Estimated Fair Value and Level Within Fair Value Hierarchy 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	2013				2012
			Fair Value	Carrying		Fair		Carrying		Fair
			Hierarchy	Amount		Value		Amount		Value
	Financial assets
	Cash		Level 1	$	1,464	$	1,464	$	1,576	$	1,576
	Cash equivalents		Level 2		145,501		145,501		134,427		134,427
	Securities available for sale		-1		131,178		131,178		138,314		138,314
	Federal Home Loan Bank stock		-2		11,961		11,961		11,961		11,961
	Loans, net		Level 3		1,030,422		1,027,300		1,012,512		1,004,541
	Bank owned life insurance		Level 2		51,377		51,377		50,048		50,048
	Accrued interest receivable		Level 2		3,649		3,649		3,874		3,874
	Financial liabilities
	Deposits		Level 2		1,118,911		1,120,576		1,135,204		1,135,614
	Securities sold under agreements to repurchase		Level 2		69,305		69,305		64,765		64,765
	Federal Home Loan Bank advances		Level 2		45,000		45,139		35,000		35,000
	Subordinated debentures		Level 2		32,990		32,974		32,990		32,943
	Accrued interest payable		Level 2		2,041		2,041		2,314		2,314
	Interest rate swap		-1		264		264		1,113		1,113
	-1	See Note 15 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.

FAIR_VALUE_MEASUREMENTS_Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2013
Fair Value Disclosures [Abstract]	'
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, 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
	The balances of assets and liabilities measured at fair value on a recurring basis as of December 31, 2012 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		$	79,098,000		$	0	$	79,098,000		$	0
	Mortgage-backed securities			21,996,000			0		21,996,000			0
	Michigan Strategic Fund bonds			11,255,000			0		11,255,000			0
	Municipal general obligation bonds			22,743,000			0		22,743,000			0
	Municipal revenue bonds			1,817,000			0		1,817,000			0
	Mutual funds			1,405,000			0		1,405,000			0
	Derivatives
	Interest rate swap agreement			(1,113,000	)		0		(1,113,000	)		0
	Total		$	137,201,000		$	0	$	137,201,000		$	0
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, 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
	The balances of assets and liabilities measured at fair value on a nonrecurring basis as of December 31, 2012 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)		$	34,406,000		$	0	$	0		$	34,406,000
	Foreclosed assets (1)			6,970,000			0		0			6,970,000
	Total		$	41,376,000		$	0	$	0		$	41,376,000
	-1	Represents carrying value and related write-downs for which adjustments are based on the estimated value of the property or other assets.

EARNINGS_PER_SHARE_Tables

EARNINGS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	The factors used in the earnings per share computation follow:
		2013		2012		2011
	Basic
	Net income attributable to common shares	$	17,033,000	$	11,505,000	$	36,142,000
	Weighted average common shares outstanding		8,710,677		8,625,198		8,602,845
	Basic earnings per common share	$	1.96	$	1.33	$	4.2
	Diluted
	Net income attributable to common shares	$	17,033,000	$	11,505,000	$	36,142,000
	Weighted average common shares outstanding for basic earnings per common share		8,710,677		8,625,198		8,602,845
	Add: Dilutive effects of share-based awards		14,031		224,429		275,335
	Average shares and dilutive potential common shares		8,724,708		8,849,627		8,878,180
	Diluted earnings per common share	$	1.95	$	1.3	$	4.07

REGULATORY_MATTERS_Tables

REGULATORY MATTERS (Tables)	12 Months Ended
	Dec. 31, 2013
Banking And Thrift [Abstract]	'
Summary of Actual Capital Levels and Minimum Levels	'
	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
	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
	2012
	Total capital (to risk weighted assets)
	Consolidated	$	173,323		14.6	%	$	94,738		8	%	$	NA		NA
	Bank		173,828		14.7			94,629		8			118,286		10	%
	Tier 1 capital (to risk weighted assets)
	Consolidated		158,349		13.4			47,369		4			NA		NA
	Bank		158,871		13.4			47,315		4			70,972		6
	Tier 1 capital (to average assets)
	Consolidated		158,349		11.3			55,995		4			NA		NA
	Bank		158,871		11.4			55,937		4			69,922		5

QUARTERLY_FINANCIAL_DATA_UNAUD1

QUARTERLY FINANCIAL DATA (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]	'
Quarterly Financial Data (Unaudited)	'
						Net Income
						Attributable to
		Interest		Net Interest		Common		Earnings per Share
		Income		Income		Shares		Basic		Diluted
	2013
	First quarter	$	14,209,000	$	11,454,000	$	4,400,000	$	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
	2012
	First quarter	$	15,553,000	$	11,869,000	$	2,552,000	$	0.3	$	0.28
	Second quarter		14,930,000		11,511,000		3,288,000		0.38		0.36
	Third quarter		14,768,000		11,584,000		2,616,000		0.3		0.3
	Fourth quarter		14,666,000		11,737,000		3,049,000		0.35		0.35

MERCANTILE_BANK_CORPORATION_PA1

MERCANTILE BANK CORPORATION (PARENT COMPANY ONLY) CONDENSED FINANCIAL STATEMENTS (Tables)	12 Months Ended
	Dec. 31, 2013
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]	'
Summary of Condensed Balance Sheets	'
	Following are condensed parent company only financial statements:
	CONDENSED BALANCE SHEETS
		2013			2012
	ASSETS
	Cash and cash equivalents	$	2,506,000		$	473,000
	Investment in bank subsidiary		179,706,000			173,019,000
	Other assets		4,740,000			7,433,000
	Total assets	$	186,952,000		$	180,925,000
	LIABILITIES AND SHAREHOLDERS’ EQUITY
	Liabilities	$	637,000		$	1,345,000
	Subordinated debentures		32,990,000			32,990,000
	Shareholders’ equity		153,325,000			146,590,000
	Total liabilities and shareholders’ equity	$	186,952,000		$	180,925,000
Summary of Condensed Statements of Income	'
	CONDENSED STATEMENTS OF INCOME
		2013			2012			2011
	Income
	Interest and dividends from subsidiaries	$	5,516,000		$	32,532,000		$	4,974,000
	Total income		5,516,000			32,532,000			4,974,000
	Expenses
	Interest expense		1,213,000			884,000			847,000
	Other operating expenses		2,773,000			1,048,000			1,059,000
	Total expenses		3,986,000			1,932,000			1,906,000
	Income before income tax expense (benefit) and equity in undistributed net income (loss) of subsidiary		1,530,000			30,600,000			3,068,000
	Federal income tax benefit		(1,042,000	)		(665,000	)		(2,272,000	)
	Equity in undistributed net income (loss) of subsidiary		14,461,000			(18,730,000	)		32,145,000
	Net income		17,033,000			12,535,000			37,485,000
	Preferred stock dividends and accretion		0			1,030,000			1,343,000
	Net income attributable to common shares	$	17,033,000		$	11,505,000		$	36,142,000
Summary of Condensed Statements of Cash Flows	'
	CONDENSED STATEMENTS OF CASH FLOWS
		2013			2012			2011
	Cash flows from operating activities
	Net income	$	17,033,000		$	12,535,000		$	37,485,000
	Adjustments to reconcile net income to net cash from (for) operating activities:
	Equity in undistributed (income) loss of subsidiary		(14,461,000	)		18,730,000			(32,145,000	)
	Stock-based compensation expense		473,000			54,000			61,000
	Change in other assets		3,244,000			(3,006,000	)		(3,619,000	)
	Change in other liabilities		(708,000	)		1,073,000			(956,000	)
	Net cash from operating activities		5,581,000			29,386,000			826,000
	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			(21,000,000	)		0
	Repurchase of common stock warrant		0			(7,465,000	)		0
	Stock option exercises, net of cashless exercises		289,000			227,000			55,000
	Employee stock purchase plan		19,000			39,000			42,000
	Dividend reinvestment plan		33,000			14,000			6,000
	Cash dividends on preferred stock		0			(496,000	)		(1,620,000	)
	Cash dividends on common stock		(3,889,000	)		(774,000	)		0
	Net cash for financing activities		(3,548,000	)		(29,455,000	)		(1,517,000	)
	Net change in cash and cash equivalents		2,033,000			(69,000	)		(691,000	)
	Cash and cash equivalents at beginning of period		473,000			542,000			1,233,000
	Cash and cash equivalents at end of period	$	2,506,000		$	473,000		$	542,000

Recovered_Sheet1

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
	Segment
Schedule Of Significant Accounting Policies [Line Items]	'	'
Mercantile Bank Corporation incorporation date	15-Jul-97	'
Mercantile Bank Corporation operational date	15-Dec-97	'
Date Mercantile Bank Mortgage Company was reorganized as Mercantile Bank Mortgage Company, LLC	1-Jan-04	'
Percentage of ownership by the Bank for limited liability company	99.00%	'
Percentage of ownership interest distributed to insurance company	1.00%	'
Mortgage company's dissolution date	1-Jan-13	'
Maturities of short-term borrowings reported net for cash flow purposes	'90 days or less	'
Net unamortized deferred loan fees amounted	$0.50	$0.70
Delinquent period on commercial and mortgage Loans	'90 days	'
Maximum period of Consumer and credit card loans	'120 days	'
Loans held for sale	$1.10	$3.50
Reversed the full valuation allowance against the net deferred tax asset that was initially recorded at December 31, 2009	31-Dec-11	'
Number of operating Segments	1	'
Buildings and related components [Member] | Minimum [Member]	'	'
Schedule Of Significant Accounting Policies [Line Items]	'	'
Property and Equipment Useful lives	'5 years	'
Buildings and related components [Member] | Maximum [Member]	'	'
Schedule Of Significant Accounting Policies [Line Items]	'	'
Property and Equipment Useful lives	'33 years	'
Furniture and Fixtures [Member] | Minimum [Member]	'	'
Schedule Of Significant Accounting Policies [Line Items]	'	'
Property and Equipment Useful lives	'3 years	'
Furniture and Fixtures [Member] | Maximum [Member]	'	'
Schedule Of Significant Accounting Policies [Line Items]	'	'
Property and Equipment Useful lives	'7 years	'
Mercantile Bank Mortgage Company [Member]	'	'
Schedule Of Significant Accounting Policies [Line Items]	'	'
Bank subsidiary year of formation	'2000	'
Mercantile Bank Mortgage Company initiated business and Real Estate	24-Oct-00	'
Mercantile Insurance Company [Member]	'	'
Schedule Of Significant Accounting Policies [Line Items]	'	'
Bank subsidiary year of formation	'2002	'
Ownership percentage of Mercantile Bank Mortgage Company, LLC	1.00%	'
Mercantile Real Estate [Member]	'	'
Schedule Of Significant Accounting Policies [Line Items]	'	'
Mercantile Bank Mortgage Company initiated business and Real Estate	21-Jul-03	'
Date of facility operations	30-Jun-05	'

Securities_Amortized_Cost_and_

Securities - Amortized Cost and Fair Value of Available for Sale Securities and Related Pre-tax Gross Unrealized Gains and Losses (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	$139,487,000	$134,664,000
Gross Unrealized Gains	1,791,000	4,038,000
Gross Unrealized Losses	-10,100,000	-388,000
Fair Value	131,178,000	138,314,000
U.S. Government agency debt obligations [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	108,279,000	78,447,000
Gross Unrealized Gains	263,000	1,039,000
Gross Unrealized Losses	-10,065,000	-388,000
Fair Value	98,477,000	79,098,000
Mortgage-backed securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	12,456,000	20,182,000
Gross Unrealized Gains	1,102,000	1,814,000
Gross Unrealized Losses	0	0
Fair Value	13,558,000	21,996,000
Michigan Strategic Fund bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	0	11,255,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	0	11,255,000
Municipal general obligation bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	16,488,000	21,700,000
Gross Unrealized Gains	388,000	1,043,000
Gross Unrealized Losses	-4,000	0
Fair Value	16,872,000	22,743,000
Municipal revenue bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	878,000	1,726,000
Gross Unrealized Gains	38,000	91,000
Gross Unrealized Losses	0	0
Fair Value	916,000	1,817,000
Mutual funds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	1,386,000	1,354,000
Gross Unrealized Gains	0	51,000
Gross Unrealized Losses	-31,000	0
Fair Value	$1,355,000	$1,405,000

Securities_Securities_with_Unr

Securities - Securities with Unrealized Losses Aggregated by Investment Category and Length of Time (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	$58,767,000	$33,555,000
Unrealized Loss, Less than 12 Months	5,833,000	388,000
Fair Value, 12 Months or More	29,679,000	0
Unrealized Loss, 12 Months or More	4,267,000	0
Fair Value	88,446,000	33,555,000
Unrealized Loss	10,100,000	388,000
U.S. Government agency debt obligations [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	57,117,000	33,555,000
Unrealized Loss, Less than 12 Months	5,798,000	388,000
Fair Value, 12 Months or More	29,679,000	0
Unrealized Loss, 12 Months or More	4,267,000	0
Fair Value	86,796,000	33,555,000
Unrealized Loss	10,065,000	388,000
Mortgage-backed securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	0	0
Unrealized Loss, Less than 12 Months	0	0
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value	0	0
Unrealized Loss	0	0
Michigan Strategic Fund bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	0	0
Unrealized Loss, Less than 12 Months	0	0
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value	0	0
Unrealized Loss	0	0
Municipal general obligation bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	295,000	0
Unrealized Loss, Less than 12 Months	4,000	0
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value	295,000	0
Unrealized Loss	4,000	0
Municipal revenue bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	0	0
Unrealized Loss, Less than 12 Months	0	0
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value	0	0
Unrealized Loss	0	0
Mutual funds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	1,355,000	0
Unrealized Loss, Less than 12 Months	31,000	0
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value	1,355,000	0
Unrealized Loss	$31,000	$0

Securities_Additional_Informat

Securities - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Number of mutual funds with unrealized losses	1	'	'
Fair value of debt securities with unrealized losses	$88,446,000	$33,555,000	'
Aggregate depreciation of securities with unrealized losses	10,100,000	388,000	'
Available for sale securities/Fair Value	131,178,000	138,314,000	'
Total securities of specific issuer, other than U.S. Government and its agencies, maximum percentage of stockholders' equity	10.00%	'	'
Debt securities[Member]	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Number of debt securities with unrealized losses	65	'	'
Michigan Strategic Fund bonds [Member]	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Fair value of debt securities with unrealized losses	0	0	'
Aggregate depreciation of securities with unrealized losses	0	0	'
Securities available for sale	10,300,000	0	0
Available for sale securities/Fair Value	0	11,255,000	'
State of Michigan and all its political subdivisions [Member]	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Amortized cost of securities	17,400,000	23,400,000	'
Available for sale securities/Fair Value	17,800,000	24,600,000	'
U.S. Government agency debt obligations and mortgage-backed securities [Member]	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Carrying value of securities pledged to secure repurchase agreements	$94,400,000	$83,800,000	'

Securities_Maturities_of_Secur

Securities - Maturities of Securities and Their Weighted Average Yields (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]	'	'
Weighted Average Yield	3.73%	'
Amortized Cost	$139,487,000	$134,664,000
Available for sale securities/Fair Value	131,178,000	138,314,000
Due in one year or less [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Weighted Average Yield	5.32%	'
Amortized Cost	2,444,000	'
Available for sale securities/Fair Value	2,494,000	'
Due from one to five years [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Weighted Average Yield	6.31%	'
Amortized Cost	1,018,000	'
Available for sale securities/Fair Value	1,047,000	'
Due from five to ten years [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Weighted Average Yield	3.13%	'
Amortized Cost	32,373,000	'
Available for sale securities/Fair Value	31,008,000	'
Due after ten years [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Weighted Average Yield	3.68%	'
Amortized Cost	89,810,000	'
Available for sale securities/Fair Value	81,716,000	'
Mortgage-backed securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Weighted Average Yield	5.17%	'
Amortized Cost	12,456,000	20,182,000
Available for sale securities/Fair Value	13,558,000	21,996,000
Mutual funds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Weighted Average Yield	2.32%	'
Amortized Cost	1,386,000	1,354,000
Available for sale securities/Fair Value	$1,355,000	$1,405,000

Recovered_Sheet2

Loans and Allowance for Loan Losses - Components of Loan Portfolio Disaggregated by Class of Loan and Percentage Change in Total Loans (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]	'	'	'
Total loans	$1,053,243,000	$1,041,189,000	$1,072,422,000
Percentage of Total Loan Portfolio	100.00%	100.00%	'
Loans and leases receivable net of deferred income increase decrease percentage	1.20%	'	'
Commercial and Industrial [Member]	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'
Total loans	286,373,000	285,322,000	'
Percentage of Total Loan Portfolio	27.20%	27.40%	'
Loans and leases receivable net of deferred income increase decrease percentage	0.40%	'	'
Commercial Vacant Land, Land Development, and Residential Construction [Member]	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'
Total loans	36,741,000	48,099,000	'
Percentage of Total Loan Portfolio	3.50%	4.60%	'
Loans and leases receivable net of deferred income increase decrease percentage	-23.60%	'	'
Commercial Real Estate - Owner Occupied [Member]	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'
Total loans	261,877,000	259,277,000	'
Percentage of Total Loan Portfolio	24.90%	24.90%	'
Loans and leases receivable net of deferred income increase decrease percentage	1.00%	'	'
Commercial Real Estate - Non-Owner Occupied [Member]	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'
Total loans	364,066,000	324,886,000	'
Percentage of Total Loan Portfolio	34.60%	31.20%	'
Loans and leases receivable net of deferred income increase decrease percentage	12.10%	'	'
Commercial Real Estate - Multi-Family and Residential Rental [Member]	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'
Total loans	37,639,000	50,922,000	'
Percentage of Total Loan Portfolio	3.50%	4.90%	'
Loans and leases receivable net of deferred income increase decrease percentage	-26.10%	'	'
Commercial Loans [Member]	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'
Total loans	986,696,000	968,506,000	996,905,000
Percentage of Total Loan Portfolio	93.70%	93.00%	'
Loans and leases receivable net of deferred income increase decrease percentage	1.90%	'	'
Retail Home Equity and Other [Member]	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'
Total loans	35,080,000	38,917,000	'
Percentage of Total Loan Portfolio	3.30%	3.70%	'
Loans and leases receivable net of deferred income increase decrease percentage	-9.90%	'	'
Retail 1-4 Family Mortgages [Member]	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'
Total loans	31,467,000	33,766,000	'
Percentage of Total Loan Portfolio	3.00%	3.30%	'
Loans and leases receivable net of deferred income increase decrease percentage	-6.80%	'	'
Retail Loans [Member]	'	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'	'
Total loans	$66,547,000	$72,683,000	$75,517,000
Percentage of Total Loan Portfolio	6.30%	7.00%	'
Loans and leases receivable net of deferred income increase decrease percentage	-8.40%	'	'

Recovered_Sheet3

Loans and Allowance for Loan Losses - Concentrations within Loan Portfolio (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Concentrations Within Loan Portfolio [Abstract]	'	'	'
Loans	$1,053,243,000	$1,041,189,000	$1,072,422,000
Percentage of Loan Portfolio	100.00%	100.00%	'
Commercial Real Estate Loans to Lessors of Non-residential Buildings [Member]	'	'	'
Concentrations Within Loan Portfolio [Abstract]	'	'	'
Loans	$299,446,000	$302,723,000	'
Percentage of Loan Portfolio	28.40%	29.10%	'

Loans_and_Allowance_for_Loan_L2

Loans and Allowance for Loan Losses - Nonperforming Loans (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Receivables [Abstract]	'	'
Loans past due 90 days or more still accruing interest	$0	$0
Nonaccrual loans	6,718,000	18,970,000
Total nonperforming loans	$6,718,000	$18,970,000

Loans_and_Allowance_for_Loan_L3

Loans and Allowance for Loan Losses - Recorded Principal Balance of Nonaccrual Loans (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]	'	'
Total nonaccrual loans	$6,718,000	$18,970,000
Commercial and Industrial [Member]	'	'
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]	'	'
Total nonaccrual loans	1,501,000	1,677,000
Commercial Vacant Land, Land Development, and Residential Construction [Member]	'	'
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]	'	'
Total nonaccrual loans	785,000	2,194,000
Commercial Real Estate - Owner Occupied [Member]	'	'
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]	'	'
Total nonaccrual loans	389,000	2,087,000
Commercial Real Estate - Non-Owner Occupied [Member]	'	'
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]	'	'
Total nonaccrual loans	168,000	9,010,000
Commercial Real Estate - Multi-Family and Residential Rental [Member]	'	'
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]	'	'
Total nonaccrual loans	208,000	2,021,000
Commercial Loans [Member]	'	'
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]	'	'
Total nonaccrual loans	3,051,000	16,989,000
Retail Home Equity and Other [Member]	'	'
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]	'	'
Total nonaccrual loans	788,000	889,000
Retail 1-4 Family Mortgages [Member]	'	'
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]	'	'
Total nonaccrual loans	2,879,000	1,092,000
Retail Loans [Member]	'	'
Financing Receivable Recorded Investment Nonaccrual Loans [Line Items]	'	'
Total nonaccrual loans	$3,667,000	$1,981,000

Loans_and_Allowance_for_Loan_L4

Loans and Allowance for Loan Losses - Age Analysis of Past Due Loans (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'	'
Total past due loans 30 - 59 Days Past Due	$100,000	$919,000	'
Total past due loans 60 - 89 Days Past Due	44,000	190,000	'
Total past due loans Greater Than 89 Days Past Due	798,000	5,008,000	'
Total Past Due	942,000	6,117,000	'
Current	1,052,301,000	1,035,072,000	'
Total Loans	1,053,243,000	1,041,189,000	1,072,422,000
Recorded Balance greater than 89 Days and Accruing	0	0	'
Commercial and Industrial [Member]	'	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'	'
Total past due loans 30 - 59 Days Past Due	0	80,000	'
Total past due loans 60 - 89 Days Past Due	0	0	'
Total past due loans Greater Than 89 Days Past Due	309,000	871,000	'
Total Past Due	309,000	951,000	'
Current	286,064,000	284,371,000	'
Total Loans	286,373,000	285,322,000	'
Recorded Balance greater than 89 Days and Accruing	0	0	'
Commercial Vacant Land, Land Development, and Residential Construction [Member]	'	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'	'
Total past due loans 30 - 59 Days Past Due	0	289,000	'
Total past due loans 60 - 89 Days Past Due	0	0	'
Total past due loans Greater Than 89 Days Past Due	0	614,000	'
Total Past Due	0	903,000	'
Current	36,741,000	47,196,000	'
Total Loans	36,741,000	48,099,000	'
Recorded Balance greater than 89 Days and Accruing	0	0	'
Commercial Real Estate - Owner Occupied [Member]	'	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'	'
Total past due loans 30 - 59 Days Past Due	65,000	199,000	'
Total past due loans 60 - 89 Days Past Due	0	0	'
Total past due loans Greater Than 89 Days Past Due	50,000	1,337,000	'
Total Past Due	115,000	1,536,000	'
Current	261,762,000	257,741,000	'
Total Loans	261,877,000	259,277,000	'
Recorded Balance greater than 89 Days and Accruing	0	0	'
Commercial Real Estate - Non-Owner Occupied [Member]	'	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'	'
Total past due loans 30 - 59 Days Past Due	0	303,000	'
Total past due loans 60 - 89 Days Past Due	0	0	'
Total past due loans Greater Than 89 Days Past Due	0	1,123,000	'
Total Past Due	0	1,426,000	'
Current	364,066,000	323,460,000	'
Total Loans	364,066,000	324,886,000	'
Recorded Balance greater than 89 Days and Accruing	0	0	'
Commercial Real Estate - Multi-Family and Residential Rental [Member]	'	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'	'
Total past due loans 30 - 59 Days Past Due	0	0	'
Total past due loans 60 - 89 Days Past Due	0	0	'
Total past due loans Greater Than 89 Days Past Due	64,000	613,000	'
Total Past Due	64,000	613,000	'
Current	37,575,000	50,309,000	'
Total Loans	37,639,000	50,922,000	'
Recorded Balance greater than 89 Days and Accruing	0	0	'
Commercial Loans [Member]	'	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'	'
Total past due loans 30 - 59 Days Past Due	65,000	871,000	'
Total past due loans 60 - 89 Days Past Due	0	0	'
Total past due loans Greater Than 89 Days Past Due	423,000	4,558,000	'
Total Past Due	488,000	5,429,000	'
Current	986,208,000	963,077,000	'
Total Loans	986,696,000	968,506,000	996,905,000
Recorded Balance greater than 89 Days and Accruing	0	0	'
Retail Home Equity and Other [Member]	'	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'	'
Total past due loans 30 - 59 Days Past Due	14,000	1,000	'
Total past due loans 60 - 89 Days Past Due	0	0	'
Total past due loans Greater Than 89 Days Past Due	0	13,000	'
Total Past Due	14,000	14,000	'
Current	35,066,000	38,903,000	'
Total Loans	35,080,000	38,917,000	'
Recorded Balance greater than 89 Days and Accruing	0	0	'
Retail 1-4 Family Mortgages [Member]	'	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'	'
Total past due loans 30 - 59 Days Past Due	21,000	47,000	'
Total past due loans 60 - 89 Days Past Due	44,000	190,000	'
Total past due loans Greater Than 89 Days Past Due	375,000	437,000	'
Total Past Due	440,000	674,000	'
Current	31,027,000	33,092,000	'
Total Loans	31,467,000	33,766,000	'
Recorded Balance greater than 89 Days and Accruing	0	0	'
Retail Loans [Member]	'	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'	'
Total past due loans 30 - 59 Days Past Due	35,000	48,000	'
Total past due loans 60 - 89 Days Past Due	44,000	190,000	'
Total past due loans Greater Than 89 Days Past Due	375,000	450,000	'
Total Past Due	454,000	688,000	'
Current	66,093,000	71,995,000	'
Total Loans	66,547,000	72,683,000	75,517,000
Recorded Balance greater than 89 Days and Accruing	$0	$0	'

Loans_and_Allowance_for_Loan_L5

Loans and Allowance for Loan Losses - Impaired Loans (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Impaired Loans By Type [Line Items]	'	'
Unpaid Contractual Principal Balance, with no related allowance	$6,689,000	$20,038,000
Impaired loans, Unpaid Contractual Principal Balance	41,056,000	69,166,000
Recorded Principal Balance, with no related allowance	3,500,000	11,752,000
Impaired loans, Recorded Principal Balance	36,868,000	57,279,000
Impaired loans, Related Allowance	'	'
Year-To-Date Average Recorded Principal Balance, with no related allowance	8,917,000	16,770,000
Unpaid Contractual Principal Balance, with related allowance	34,367,000	49,128,000
Recorded Principal Balance, with related allowance	33,368,000	45,527,000
Impaired loans, Related Allowance	12,386,000	17,189,000
Year-To-Date Average Recorded Principal Balance, with related allowance	41,044,000	44,548,000
Impaired loans, Year-To-Date Average Recorded Principal Balance	49,961,000	61,318,000
Commercial and Industrial [Member]	'	'
Impaired Loans By Type [Line Items]	'	'
Unpaid Contractual Principal Balance, with no related allowance	2,229,000	1,926,000
Recorded Principal Balance, with no related allowance	511,000	1,617,000
Impaired loans, Related Allowance	'	'
Year-To-Date Average Recorded Principal Balance, with no related allowance	1,205,000	3,140,000
Unpaid Contractual Principal Balance, with related allowance	1,517,000	3,221,000
Recorded Principal Balance, with related allowance	1,440,000	1,926,000
Impaired loans, Related Allowance	792,000	924,000
Year-To-Date Average Recorded Principal Balance, with related allowance	1,880,000	3,110,000
Commercial Vacant Land, Land Development, and Residential Construction [Member]	'	'
Impaired Loans By Type [Line Items]	'	'
Unpaid Contractual Principal Balance, with no related allowance	475,000	2,356,000
Recorded Principal Balance, with no related allowance	362,000	1,401,000
Impaired loans, Related Allowance	'	'
Year-To-Date Average Recorded Principal Balance, with no related allowance	991,000	1,848,000
Unpaid Contractual Principal Balance, with related allowance	4,436,000	2,333,000
Recorded Principal Balance, with related allowance	4,139,000	2,219,000
Impaired loans, Related Allowance	844,000	1,367,000
Year-To-Date Average Recorded Principal Balance, with related allowance	3,354,000	3,267,000
Commercial Real Estate - Owner Occupied [Member]	'	'
Impaired Loans By Type [Line Items]	'	'
Unpaid Contractual Principal Balance, with no related allowance	1,270,000	2,368,000
Recorded Principal Balance, with no related allowance	785,000	1,557,000
Impaired loans, Related Allowance	'	'
Year-To-Date Average Recorded Principal Balance, with no related allowance	1,084,000	3,139,000
Unpaid Contractual Principal Balance, with related allowance	1,513,000	4,307,000
Recorded Principal Balance, with related allowance	1,513,000	3,626,000
Impaired loans, Related Allowance	528,000	1,388,000
Year-To-Date Average Recorded Principal Balance, with related allowance	2,550,000	4,913,000
Commercial Real Estate - Non-Owner Occupied [Member]	'	'
Impaired Loans By Type [Line Items]	'	'
Unpaid Contractual Principal Balance, with no related allowance	895,000	9,984,000
Recorded Principal Balance, with no related allowance	733,000	5,492,000
Impaired loans, Related Allowance	'	'
Year-To-Date Average Recorded Principal Balance, with no related allowance	4,049,000	6,578,000
Unpaid Contractual Principal Balance, with related allowance	21,088,000	33,818,000
Recorded Principal Balance, with related allowance	21,072,000	32,964,000
Impaired loans, Related Allowance	7,969,000	11,773,000
Year-To-Date Average Recorded Principal Balance, with related allowance	28,388,000	25,061,000
Commercial Real Estate - Multi-Family and Residential Rental [Member]	'	'
Impaired Loans By Type [Line Items]	'	'
Unpaid Contractual Principal Balance, with no related allowance	41,000	1,188,000
Recorded Principal Balance, with no related allowance	1,000	413,000
Impaired loans, Related Allowance	'	'
Year-To-Date Average Recorded Principal Balance, with no related allowance	390,000	756,000
Unpaid Contractual Principal Balance, with related allowance	3,219,000	4,471,000
Recorded Principal Balance, with related allowance	2,684,000	3,923,000
Impaired loans, Related Allowance	1,127,000	1,408,000
Year-To-Date Average Recorded Principal Balance, with related allowance	2,915,000	7,429,000
Commercial Loans [Member]	'	'
Impaired Loans By Type [Line Items]	'	'
Unpaid Contractual Principal Balance, with no related allowance	4,910,000	17,822,000
Impaired loans, Unpaid Contractual Principal Balance	36,683,000	65,972,000
Recorded Principal Balance, with no related allowance	2,392,000	10,480,000
Impaired loans, Recorded Principal Balance	33,240,000	55,138,000
Impaired loans, Related Allowance	'	'
Year-To-Date Average Recorded Principal Balance, with no related allowance	7,719,000	15,461,000
Unpaid Contractual Principal Balance, with related allowance	31,773,000	48,150,000
Recorded Principal Balance, with related allowance	30,848,000	44,658,000
Impaired loans, Related Allowance	11,260,000	16,860,000
Year-To-Date Average Recorded Principal Balance, with related allowance	39,087,000	43,780,000
Impaired loans, Year-To-Date Average Recorded Principal Balance	46,806,000	59,241,000
Retail Home Equity and Other [Member]	'	'
Impaired Loans By Type [Line Items]	'	'
Unpaid Contractual Principal Balance, with no related allowance	507,000	580,000
Recorded Principal Balance, with no related allowance	461,000	483,000
Impaired loans, Related Allowance	'	'
Year-To-Date Average Recorded Principal Balance, with no related allowance	471,000	579,000
Unpaid Contractual Principal Balance, with related allowance	320,000	423,000
Recorded Principal Balance, with related allowance	289,000	394,000
Impaired loans, Related Allowance	96,000	204,000
Year-To-Date Average Recorded Principal Balance, with related allowance	329,000	286,000
Retail 1-4 Family Mortgages [Member]	'	'
Impaired Loans By Type [Line Items]	'	'
Unpaid Contractual Principal Balance, with no related allowance	1,272,000	1,636,000
Recorded Principal Balance, with no related allowance	647,000	789,000
Impaired loans, Related Allowance	'	'
Year-To-Date Average Recorded Principal Balance, with no related allowance	727,000	730,000
Unpaid Contractual Principal Balance, with related allowance	2,274,000	555,000
Recorded Principal Balance, with related allowance	2,231,000	475,000
Impaired loans, Related Allowance	1,030,000	125,000
Year-To-Date Average Recorded Principal Balance, with related allowance	1,628,000	482,000
Retail Loans [Member]	'	'
Impaired Loans By Type [Line Items]	'	'
Unpaid Contractual Principal Balance, with no related allowance	1,779,000	2,216,000
Impaired loans, Unpaid Contractual Principal Balance	4,373,000	3,194,000
Recorded Principal Balance, with no related allowance	1,108,000	1,272,000
Impaired loans, Recorded Principal Balance	3,628,000	2,141,000
Impaired loans, Related Allowance	'	'
Year-To-Date Average Recorded Principal Balance, with no related allowance	1,198,000	1,309,000
Unpaid Contractual Principal Balance, with related allowance	2,594,000	978,000
Recorded Principal Balance, with related allowance	2,520,000	869,000
Impaired loans, Related Allowance	1,126,000	329,000
Year-To-Date Average Recorded Principal Balance, with related allowance	1,957,000	768,000
Impaired loans, Year-To-Date Average Recorded Principal Balance	$3,155,000	$2,077,000

Loans_and_Allowance_for_Loan_L6

Loans and Allowance for Loan Losses - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Receivables [Abstract]	'	'	'
Interest income recognized on accruing troubled debt restructuring	$2.50	$2	$0.20
Interest income recognized on nonaccrual loans	1.9	0	0
Lost interest income on nonaccrual loans	$0.40	$0.80	$1.40
Number of past due days for loans modified as TDR	'30 days	'30 days	'

Loans_and_Allowance_for_Loan_L7

Loans and Allowance for Loan Losses - Loans by Credit Quality Indicators (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	$1,053,243,000	$1,041,189,000	$1,072,422,000
Commercial and Industrial [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	286,373,000	285,322,000	'
Commercial and Industrial [Member] | Grades 1-4 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	208,151,000	180,314,000	'
Commercial and Industrial [Member] | Grades 5-7 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	76,237,000	101,832,000	'
Commercial and Industrial [Member] | Grades 8-9 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	1,985,000	3,176,000	'
Commercial Vacant Land, Land Development, and Residential Construction [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	36,741,000	48,099,000	'
Commercial Vacant Land, Land Development, and Residential Construction [Member] | Grades 1-4 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	6,973,000	6,526,000	'
Commercial Vacant Land, Land Development, and Residential Construction [Member] | Grades 5-7 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	25,535,000	37,697,000	'
Commercial Vacant Land, Land Development, and Residential Construction [Member] | Grades 8-9 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	4,233,000	3,876,000	'
Commercial Real Estate - Owner Occupied [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	261,877,000	259,277,000	'
Commercial Real Estate - Owner Occupied [Member] | Grades 1-4 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	156,230,000	150,467,000	'
Commercial Real Estate - Owner Occupied [Member] | Grades 5-7 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	103,066,000	102,988,000	'
Commercial Real Estate - Owner Occupied [Member] | Grades 8-9 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	2,581,000	5,822,000	'
Commercial Real Estate - Non-Owner Occupied [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	364,066,000	324,886,000	'
Commercial Real Estate - Non-Owner Occupied [Member] | Grades 1-4 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	219,325,000	154,127,000	'
Commercial Real Estate - Non-Owner Occupied [Member] | Grades 5-7 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	122,717,000	128,041,000	'
Commercial Real Estate - Non-Owner Occupied [Member] | Grades 8-9 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	22,024,000	42,718,000	'
Commercial Real Estate - Multi-Family and Residential Rental [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	37,639,000	50,922,000	'
Commercial Real Estate - Multi-Family and Residential Rental [Member] | Grades 1-4 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	15,465,000	24,015,000	'
Commercial Real Estate - Multi-Family and Residential Rental [Member] | Grades 5-7 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	19,469,000	22,082,000	'
Commercial Real Estate - Multi-Family and Residential Rental [Member] | Grades 8-9 [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	2,705,000	4,825,000	'
Retail Home Equity and Other [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	35,080,000	38,917,000	'
Retail 1-4 Family Mortgages [Member]	'	'	'
Financing Receivable Credit Quality Indicator [Line Items]	'	'	'
Total loans	$31,467,000	$33,766,000	'

Loans_and_Allowance_for_Loan_L8

Loans and Allowance for Loan Losses - Activity in Allowance for Loan Losses and Recorded Investments in Loans (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Beginning balance	$28,677,000	$36,532,000	$45,368,000
Provision for loan losses	-7,200,000	-3,100,000	6,900,000
Charge-offs	-5,290,000	-12,644,000	-19,897,000
Recoveries	6,634,000	7,889,000	4,161,000
Ending balance	22,821,000	28,677,000	36,532,000
Ending balance: individually evaluated for impairment	12,386,000	17,189,000	18,996,000
Ending balance: collectively evaluated for impairment	10,435,000	11,488,000	17,536,000
Ending balance	1,053,243,000	1,041,189,000	1,072,422,000
Ending balance: individually evaluated for impairment	36,868,000	57,279,000	70,978,000
Ending balance: collectively evaluated for impairment	1,016,375,000	983,910,000	1,001,444,000
Commercial Loans [Member]	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Beginning balance	26,043,000	33,431,000	42,359,000
Provision for loan losses	-6,730,000	-2,800,000	4,125,000
Charge-offs	-5,120,000	-12,075,000	-16,978,000
Recoveries	6,262,000	7,487,000	3,925,000
Ending balance	20,455,000	26,043,000	33,431,000
Ending balance: individually evaluated for impairment	11,260,000	16,860,000	18,645,000
Ending balance: collectively evaluated for impairment	9,195,000	9,183,000	14,786,000
Ending balance	986,696,000	968,506,000	996,905,000
Ending balance: individually evaluated for impairment	33,240,000	55,138,000	68,893,000
Ending balance: collectively evaluated for impairment	953,456,000	913,368,000	928,012,000
Retail Loans [Member]	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Beginning balance	2,645,000	3,019,000	2,972,000
Provision for loan losses	-489,000	-207,000	2,730,000
Charge-offs	-170,000	-569,000	-2,919,000
Recoveries	372,000	402,000	236,000
Ending balance	2,358,000	2,645,000	3,019,000
Ending balance: individually evaluated for impairment	1,126,000	329,000	351,000
Ending balance: collectively evaluated for impairment	1,232,000	2,316,000	2,668,000
Ending balance	66,547,000	72,683,000	75,517,000
Ending balance: individually evaluated for impairment	3,628,000	2,141,000	2,085,000
Ending balance: collectively evaluated for impairment	62,919,000	70,542,000	73,432,000
Unallocated [Member]	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Beginning balance	-11,000	82,000	37,000
Provision for loan losses	19,000	-93,000	45,000
Charge-offs	0	0	0
Recoveries	0	0	0
Ending balance	8,000	-11,000	82,000
Ending balance: individually evaluated for impairment	0	0	0
Ending balance: collectively evaluated for impairment	$8,000	($11,000)	$82,000

Loans_and_Allowance_for_Loan_L9

Loans and Allowance for Loan Losses - Loans Modified as Troubled Debt Restructurings (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
	Contract	Contract
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Financing Receivable Modification, Number of Contracts	10	29
Financing Receivable Modification, Pre-Modification Recorded Principal Balance	$7,231,000	$32,089,000
Financing Receivable Modification, Post-Modification Recorded Principal Balance	7,231,000	32,084,000
Commercial and industrial [Member]	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Financing Receivable Modification, Number of Contracts	3	8
Financing Receivable Modification, Pre-Modification Recorded Principal Balance	741,000	1,357,000
Financing Receivable Modification, Post-Modification Recorded Principal Balance	741,000	1,353,000
Vacant land, land development and residential construction [Member]	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Financing Receivable Modification, Number of Contracts	2	0
Financing Receivable Modification, Pre-Modification Recorded Principal Balance	3,610,000	0
Financing Receivable Modification, Post-Modification Recorded Principal Balance	3,610,000	0
Real estate - owner occupied [Member]	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Financing Receivable Modification, Number of Contracts	2	6
Financing Receivable Modification, Pre-Modification Recorded Principal Balance	715,000	1,745,000
Financing Receivable Modification, Post-Modification Recorded Principal Balance	715,000	1,744,000
Real estate - non-owner occupied [Member]	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Financing Receivable Modification, Number of Contracts	1	15
Financing Receivable Modification, Pre-Modification Recorded Principal Balance	45,000	28,987,000
Financing Receivable Modification, Post-Modification Recorded Principal Balance	45,000	28,987,000
Real estate - multi-family and residential rental [Member]	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Financing Receivable Modification, Number of Contracts	1	0
Financing Receivable Modification, Pre-Modification Recorded Principal Balance	241,000	0
Financing Receivable Modification, Post-Modification Recorded Principal Balance	241,000	0
Commercial Loans [Member]	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Financing Receivable Modification, Number of Contracts	9	29
Financing Receivable Modification, Pre-Modification Recorded Principal Balance	5,352,000	32,089,000
Financing Receivable Modification, Post-Modification Recorded Principal Balance	5,352,000	32,084,000
Home equity and other [Member]	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Financing Receivable Modification, Number of Contracts	0	0
Financing Receivable Modification, Pre-Modification Recorded Principal Balance	0	0
Financing Receivable Modification, Post-Modification Recorded Principal Balance	0	0
1 - 4 family mortgages [Member]	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Financing Receivable Modification, Number of Contracts	1	0
Financing Receivable Modification, Pre-Modification Recorded Principal Balance	1,879,000	0
Financing Receivable Modification, Post-Modification Recorded Principal Balance	1,879,000	0
Retail Loans [Member]	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Financing Receivable Modification, Number of Contracts	1	0
Financing Receivable Modification, Pre-Modification Recorded Principal Balance	1,879,000	0
Financing Receivable Modification, Post-Modification Recorded Principal Balance	$1,879,000	$0

Recovered_Sheet4

Loans and Allowance for Loan Losses - Loans, Modified As Troubled Debt Restructurings within the Previous Twelve Months, That Became Over 30 Days Past Due (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
	Contract	Contract
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	1	0
Recorded Principal Balance	$65,000	$0
Commercial Loans [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	1	0
Recorded Principal Balance	65,000	0
Commercial Loans [Member] | Commercial and industrial [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	0	0
Recorded Principal Balance	0	0
Commercial Loans [Member] | Vacant land, land development and residential construction [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	0	0
Recorded Principal Balance	0	0
Commercial Loans [Member] | Real estate - owner occupied [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	1	0
Recorded Principal Balance	65,000	0
Commercial Loans [Member] | Real estate - non-owner occupied [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	0	0
Recorded Principal Balance	0	0
Commercial Loans [Member] | Real estate - multi-family and residential rental [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	0	0
Recorded Principal Balance	0	0
Retail Loans [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	0	0
Recorded Principal Balance	0	0
Retail Loans [Member] | Home equity and other [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	0	0
Recorded Principal Balance	0	0
Retail Loans [Member] | 1 - 4 family mortgages [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	0	0
Recorded Principal Balance	$0	$0

Recovered_Sheet5

Loans and Allowance for Loan Losses - Activity for Loans Categorized as Troubled Debt Restructurings (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Commercial and Industrial [Member]	'	'	'
Schedule Of Troubled Debt Restructured Loans [Line Items]	'	'	'
Beginning Balance	$2,720,000	$4,553,000	$850,000
Charge-Offs	-35,000	-540,000	-850,000
Payments	-2,781,000	-2,584,000	0
Transfers to ORE	-74,000	-96,000	0
Net Additions/Deletions	1,826,000	1,387,000	4,553,000
Ending Balance	1,656,000	2,720,000	4,553,000
Commercial Vacant Land, Land Development, and Residential Construction [Member]	'	'	'
Schedule Of Troubled Debt Restructured Loans [Line Items]	'	'	'
Beginning Balance	3,071,000	5,100,000	10,696,000
Charge-Offs	-725,000	-63,000	-2,429,000
Payments	-1,596,000	-2,013,000	-3,137,000
Transfers to ORE	0	0	-5,130,000
Net Additions/Deletions	3,751,000	47,000	5,100,000
Ending Balance	4,501,000	3,071,000	5,100,000
Commercial Real Estate - Owner Occupied [Member]	'	'	'
Schedule Of Troubled Debt Restructured Loans [Line Items]	'	'	'
Beginning Balance	4,116,000	6,183,000	2,589,000
Charge-Offs	-70,000	-426,000	0
Payments	-2,151,000	-3,443,000	-2,477,000
Transfers to ORE	-363,000	-65,000	0
Net Additions/Deletions	284,000	1,867,000	6,071,000
Ending Balance	1,816,000	4,116,000	6,183,000
Commercial Real Estate - Non-Owner Occupied [Member]	'	'	'
Schedule Of Troubled Debt Restructured Loans [Line Items]	'	'	'
Beginning Balance	37,671,000	12,036,000	9,330,000
Charge-Offs	-2,537,000	-720,000	-1,195,000
Payments	-13,795,000	-2,482,000	-3,614,000
Transfers to ORE	-1,153,000	-1,045,000	0
Net Additions/Deletions	2,125,000	29,882,000	7,515,000
Ending Balance	22,311,000	37,671,000	12,036,000
Commercial Real Estate - Multi-Family and Residential Rental [Member]	'	'	'
Schedule Of Troubled Debt Restructured Loans [Line Items]	'	'	'
Beginning Balance	3,027,000	12,626,000	7,848,000
Charge-Offs	-15,000	-2,180,000	-21,000
Payments	-735,000	-7,422,000	-92,000
Transfers to ORE	0	-186,000	0
Net Additions/Deletions	343,000	189,000	4,891,000
Ending Balance	2,620,000	3,027,000	12,626,000
Retail Home Equity and Other [Member]	'	'	'
Schedule Of Troubled Debt Restructured Loans [Line Items]	'	'	'
Beginning Balance	0	0	0
Charge-Offs	0	0	0
Payments	0	0	0
Transfers to ORE	0	0	0
Net Additions/Deletions	0	0	0
Ending Balance	0	0	0
Retail 1-4 Family Mortgages [Member]	'	'	'
Schedule Of Troubled Debt Restructured Loans [Line Items]	'	'	'
Beginning Balance	155,000	164,000	0
Charge-Offs	0	0	0
Payments	-46,000	-9,000	0
Transfers to ORE	0	0	0
Net Additions/Deletions	1,878,000	0	164,000
Ending Balance	$1,987,000	$155,000	$164,000

Recovered_Sheet6

Loans and Allowance for Loan Losses - Allowance Related to Loans Categorized as Troubled Debt Restructurings (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	$22,821,000	$28,677,000	$36,532,000	$45,368,000
Commercial Loans [Member]	'	'	'	'
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	20,455,000	26,043,000	33,431,000	42,359,000
Retail Loans [Member]	'	'	'	'
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	2,358,000	2,645,000	3,019,000	2,972,000
Financing Receivable Troubled Debt Restructuring [Member]	'	'	'	'
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	10,351,000	13,097,000	'	'
Financing Receivable Troubled Debt Restructuring [Member] | Commercial and Industrial [Member]	'	'	'	'
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	187,000	772,000	'	'
Financing Receivable Troubled Debt Restructuring [Member] | Commercial Vacant Land, Land Development, and Residential Construction [Member]	'	'	'	'
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	798,000	713,000	'	'
Financing Receivable Troubled Debt Restructuring [Member] | Commercial Real Estate - Owner Occupied [Member]	'	'	'	'
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	528,000	1,116,000	'	'
Financing Receivable Troubled Debt Restructuring [Member] | Commercial Real Estate - Non-Owner Occupied [Member]	'	'	'	'
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	7,828,000	9,751,000	'	'
Financing Receivable Troubled Debt Restructuring [Member] | Commercial Real Estate - Multi-Family and Residential Rental [Member]	'	'	'	'
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	1,010,000	745,000	'	'
Financing Receivable Troubled Debt Restructuring [Member] | Commercial Loans [Member]	'	'	'	'
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	10,351,000	13,097,000	'	'
Financing Receivable Troubled Debt Restructuring [Member] | Home equity and other [Member]	'	'	'	'
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	0	0	'	'
Financing Receivable Troubled Debt Restructuring [Member] | 1 - 4 family mortgages [Member]	'	'	'	'
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	0	0	'	'
Financing Receivable Troubled Debt Restructuring [Member] | Retail Loans [Member]	'	'	'	'
Schedule Of Financing Receivable Troubled Debt Restructurings [Line Items]	'	'	'	'
Total	$0	$0	'	'

Premises_and_Equipment_Net_Sum

Premises and Equipment, Net - Summary of Premises and Equipment (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]	'	'
Premises and equipment, gross	$46,007,000	$45,981,000
Less: accumulated depreciation	21,109,000	20,062,000
Premises and equipment, net	24,898,000	25,919,000
Land and improvements [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Premises and equipment, gross	8,556,000	8,556,000
Buildings [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Premises and equipment, gross	24,733,000	24,564,000
Furniture and equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Premises and equipment, gross	$12,718,000	$12,861,000

Premises_and_Equipment_Net_Add

Premises and Equipment, Net - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property Plant And Equipment Useful Life And Values [Abstract]	'	'	'
Depreciation expense	$1.30	$1.50	$1.60

Deposits_Components_of_Outstan

Deposits - Components of Outstanding Balances and Percentage Change in Deposits (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Deposits By Component Alternative [Abstract]	'	'
Noninterest-bearing demand	$224,580,000	$190,241,000
Interest-bearing checking	197,388,000	188,057,000
Money market	133,369,000	144,479,000
Savings	52,606,000	56,454,000
Time, under $100,000	43,251,000	51,730,000
Time, $100,000 and over	254,600,000	234,430,000
Total Local Deposits	905,794,000	865,391,000
Out-of-area interest-bearing checking	0	21,967,000
Out-of-area time, under $100,000	4,078,000	7,706,000
Out-of-area time, $100,000 and over	209,039,000	240,140,000
Total out-of-area deposits	213,117,000	269,813,000
Total deposits	$1,118,911,000	$1,135,204,000
Percentage of Noninterest-bearing demand	20.10%	16.80%
Percentage of Interest-bearing checking	17.60%	16.50%
Percentage of Money market	11.90%	12.70%
Percentage of Savings	4.70%	5.00%
Percentage of time, under $100,000	3.90%	4.60%
Percentage of time, $100,000 and over	22.80%	20.60%
Percentage of total local deposits	81.00%	76.20%
Percentage of out-of-area interest-bearing checking	'	1.90%
Percentage of out-of-area time, under $100,000	0.40%	0.70%
Percentage of out-of-area time, $100,000 and over	18.60%	21.20%
Aggregate percentage of out-of-area deposits	19.00%	23.80%
Aggregate percentage of total deposits	100.00%	100.00%
Percentage of Increase or (Decrease) in Noninterest-bearing demand	18.10%	'
Percentage of Increase or (Decrease) of Interest-bearing checking Deposits	5.00%	'
Percentage of Increase or (Decrease) of Money market Deposits	-7.70%	'
Percentage of Increase or (Decrease) of Savings Deposits	-6.80%	'
Percentage of Increase or (Decrease) in Time, under $100,000	-16.40%	'
Percentage of Increase or (Decrease) in Time, $100,000 and over	8.60%	'
Percentage of Increase or (Decrease) in Total Local Deposits	4.70%	'
Percentage of Increase or (Decrease) in out-of-area interest-bearing checking	'	'
Percentage of Increase or (Decrease) in out-of- area time, under $100,000	-47.10%	'
Percentage Increase or (Decrease) in out-of-area time, $100,000 and over	-13.00%	'
Aggregate Percentage Increase or (Decrease) in out-of-area deposits	-21.00%	'
Aggregate Percentage Increase or (Decrease) in Total Deposits	-1.40%	'

Deposits_Maturity_Distribution

Deposits - Maturity Distribution for Certificates of Deposit (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Time Deposits By Maturity [Abstract]	'	'
In one year or less	$213,454,000	$246,630,000
In one to two years	80,138,000	61,004,000
In two to three years	73,271,000	67,635,000
In three to four years	95,979,000	63,894,000
In four to five years	48,126,000	94,843,000
Total certificates of deposit	$510,968,000	$534,006,000

Deposits_Maturity_Distribution1

Deposits - Maturity Distribution for Certificates of Deposit of More Than Specified Amount (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Contractual Maturities Of Time Deposits 100000 Or More Disclosures [Abstract]	'	'
Up to three months	$57,469,000	$100,460,000
Three months to six months	41,237,000	51,762,000
Six months to twelve months	93,920,000	64,633,000
Over twelve months	271,013,000	257,715,000
Total certificates of deposit	$463,639,000	$474,570,000

Recovered_Sheet7

Securities Sold Under Agreements To Repurchase - Securities Sold Under Agreements to Repurchase (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Debt Disclosure [Abstract]	'	'
Outstanding balance at year-end	$69,305,000	$64,765,000
Weighted average interest rate at year-end	0.12%	0.13%
Average daily balance during the year	65,939,000	61,930,000
Weighted average interest rate during the year	0.12%	0.25%
Maximum daily balance during the year	$78,960,000	$81,980,000

Recovered_Sheet8

Securities Sold Under Agreements To Repurchase - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Repurchase agreements original maturity description	'Less than one year

Recovered_Sheet9

Federal Home Loan Bank Advances - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Line of Credit Facility [Line Items]	'	'
Federal Home Loan Bank advances	$45,000,000	$35,000,000
Start date of maturities	'2017-03	'2017-03
End date of maturities	'2017-09	'2017-09
Average rate of interest maturities	1.34%	1.35%
Borrowing line of credit facility	171,900,000	'
Available borrowing capacity under line of credit	$116,100,000	'
Minimum [Member]	'	'
Line of Credit Facility [Line Items]	'	'
Fixed rate of interest on maturities	1.22%	1.22%
Maximum [Member]	'	'
Line of Credit Facility [Line Items]	'	'
Fixed rate of interest on maturities	1.51%	1.51%

Recovered_Sheet10

Federal Home Loan Bank Advances - Maturities of Currently Outstanding FHLB Advances (Detail) (USD $)	Dec. 31, 2013
Debt Disclosure [Abstract]	'
2014	$0
2015	0
2016	0
2017	45,000,000
2018	$0

Federal_Income_Taxes_Consolida

Federal Income Taxes - Consolidated Income Tax Expense (Benefit) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'
Current expense (benefit)	$0	$0	$0
Deferred expense (benefit)	8,092,000	5,636,000	0
Valuation allowance - change in estimate	0	0	-27,361,000
Tax expense (benefit)	$8,092,000	$5,636,000	($27,361,000)

Federal_Income_Taxes_Reconcili

Federal Income Taxes - Reconciliation of Differences between Federal Income Tax Expense (Benefit) Recorded and Amount Computed by Applying Federal Statutory Rate to Income Before Income Taxes (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Abstract]	'	'	'
Tax at statutory rate (35%)	$8,794,000	$6,360,000	$3,543,000
Increase (decrease) from Tax-exempt interest	-347,000	-486,000	-595,000
Bank owned life insurance	-465,000	-535,000	-622,000
Change in valuation allowance	0	0	-29,640,000
Other	110,000	297,000	-47,000
Tax expense (benefit)	$8,092,000	$5,636,000	($27,361,000)

Federal_Income_Taxes_Significa

Federal Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Deferred income tax assets	'	'
Allowance for loan losses	$7,987,000	$10,037,000
Net operating loss carryforward	4,050,000	8,235,000
Unrealized loss on securities	2,908,000	0
Tax credit carryforwards	1,397,000	1,198,000
Nonaccrual loan interest income	605,000	892,000
Deferred compensation	567,000	506,000
Deferred loan fees	273,000	229,000
Fair value write-downs on foreclosed properties	241,000	2,124,000
Fair value of interest rate swap	92,000	390,000
Contributions carryforwards	0	256,000
Other	343,000	369,000
Deferred income tax assets, Total	18,463,000	24,236,000
Deferred income tax liabilities	'	'
Depreciation	419,000	491,000
Prepaid expenses	192,000	339,000
Unrealized gain on securities	0	1,278,000
Other	98,000	113,000
Deferred income tax liabilities, Total	709,000	2,221,000
Total net deferred tax asset	$17,754,000	$22,015,000

Federal_Income_Taxes_Additiona

Federal Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2011	Dec. 31, 2012
Income Tax Disclosure [Abstract]	'	'	'
Gross federal net operating loss	$11,900,000	'	'
Start expiry date	'2030	'	'
End expiry date	'2031	'	'
General business tax credits	500,000	'	'
Expiry date	'2028	'	'
Expiry end date	'2033	'	'
Federal alternative minimum tax credits with an indefinite life	900,000	'	'
Net operating loss relates to unrealized excess benefits	300,000	'	'
Reversal of valuation allowance against net deferred tax asset	'	27,400,000	'
Reversal of valuation allowance against net deferred tax asset resulting from 2011 pre-tax income	'	2,200,000	'
Unrecognized tax benefits	0	'	0
Accruals of any interest or penalties	$0	'	$0

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'
Stock option grants	0	0	0	0	0
Stock option or restricted stock grants under 2000 and 2004 Employee stock option plans, Independent Director Stock Option Plan, and Stock Incentive Plan of 2006, vesting period	'1 year	'	'	'	'
Stock options granted to non-executive officers during 2005	'3 weeks	'	'	'	'
Stock options granted to non-employee directors under Independent Director Stock Option Plan, purchase price as a percentage of market price on date of grant	125.00%	'	'	'	'
Number of shares authorized for future incentive awards under our Stock Incentive Plan of 2006	384,000	'	'	'	'
Unrecognized compensation cost related to unvested stock options granted under various stock-based compensation plans	$0	'	'	'	'
Total unrecognized compensation costs relating to unvested restricted stock granted under Stock Incentive Plan of 2006	400,000	'	'	'	'
Intrinsic value of all stock options outstanding and exercisable	100,000	'	'	'	'
Maximum [Member]	'	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'
Stock options granted to employees under 2000, and 2004 Employee Stock Option Plans, Independent Director Stock Option Plan, and Stock Incentive Plan of 2006, expiration period	'10 years	'	'	'	'
Restricted stock [Member]	'	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'
Stock option or restricted stock grants under 2000 and 2004 Employee stock option plans, Independent Director Stock Option Plan, and Stock Incentive Plan of 2006, vesting period	'4 years	'	'	'	'
Payments received from employees for restricted stock awards	$0	'	'	'	'
Stock Options [Member]	'	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'
Stock options granted to employees under 2000, and 2004 Employee Stock Option Plans, Independent Director Stock Option Plan, and Stock Incentive Plan of 2006, expiration period	'7 years	'	'	'	'
Stock option or restricted stock grants under 2000 and 2004 Employee stock option plans, Independent Director Stock Option Plan, and Stock Incentive Plan of 2006, vesting period	'2 years	'	'	'	'
Director Stock Option Plan [Member]	'	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'
Stock options granted to employees under 2000, and 2004 Employee Stock Option Plans, Independent Director Stock Option Plan, and Stock Incentive Plan of 2006, expiration period	'10 years	'	'	'	'
Stock option or restricted stock grants under 2000 and 2004 Employee stock option plans, Independent Director Stock Option Plan, and Stock Incentive Plan of 2006, vesting period	'5 years	'	'	'	'
Director Stock Option Plan [Member] | Restricted stock [Member]	'	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'
Stock option or restricted stock grants under 2000 and 2004 Employee stock option plans, Independent Director Stock Option Plan, and Stock Incentive Plan of 2006, vesting period	'2 years	'	'	'	'

StockBased_Compensation_Summar

Stock-Based Compensation - Summary of Restricted Stock Activity (Detail) (Restricted stock [Member], USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Restricted stock [Member]	'	'	'
Reconciliation Of Restricted Stock Activity [Line Items]	'	'	'
Shares, Nonvested at beginning of year	66,100	38,650	73,955
Shares, Granted	0	66,100	0
Shares, Vested	0	-38,266	-28,533
Shares, Forfeited	-2,300	-384	-6,772
Shares, Nonvested at end of year	63,800	66,100	38,650
Weighted Average Fair Value, Nonvested at beginning of year	$14.30	$6.20	$11.02
Weighted Average Fair Value, Granted	'	$14.30	'
Weighted Average Fair Value, Vested	'	$6.20	$17.57
Weighted Average Fair Value, Forfeited	$14.30	$6.20	$10.99
Weighted Average Fair Value, Nonvested at end of year	$14.30	$14.30	$6.20

StockBased_Compensation_Summar1

Stock-Based Compensation - Summary of Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'
Outstanding at beginning of year, Shares	152,896	214,903	262,042
Granted ,Shares	0	0	0
Exercised ,Shares	-51,055	-50,930	-8,800
Forfeited or expired ,Shares	-40,965	-11,077	-38,339
Outstanding at end of year ,Shares	60,876	152,896	214,903
Options exercisable at year-end ,Shares	60,876	152,896	212,643
Weighted Average Exercise Price, Outstanding at beginning of year	$26.15	$22.40	$21.18
Weighted Average Exercise Price, Granted	'	'	'
Weighted Average Exercise Price, Exercised	$13.72	$10.83	$6.21
Weighted Average Exercise Price, Forfeited or expired	$31.30	$23.77	$17.80
Weighted Average Exercise Price, Outstanding at end of year	$33.11	$26.15	$22.40
Weighted Average Exercise Price, Options exercisable at year-end	$33.11	$26.15	$22.57

StockBased_Compensation_Summar2

Stock-Based Compensation - Summary of Options Outstanding (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule Of Stock Option Activity [Line Items]	'	'	'
Exercise price range, lower range limit	$6.21	$6.21	$6.21
Exercise price range, upper range limit	$40.28	$40.28	$40.28
Number of Options Outstanding	60,876	'	'
Weighted Average Remaining Contractual Life	'1 year 4 months 24 days	'1 year 10 months 24 days	'2 years 9 months 18 days
Weighted Average Exercise Price	$33.11	'	'
Number of Options Exercisable	60,876	'	'
Options Exercisable, Weighted Average Exercise Price	$33.11	'	'
Price Range One [Member]	'	'	'
Schedule Of Stock Option Activity [Line Items]	'	'	'
Exercise price range, lower range limit	$6.21	'	'
Exercise price range, upper range limit	$8	'	'
Number of Options Outstanding	2,700	'	'
Weighted Average Remaining Contractual Life	'1 year 10 months 24 days	'	'
Weighted Average Exercise Price	$6.21	'	'
Number of Options Exercisable	2,700	'	'
Options Exercisable, Weighted Average Exercise Price	$6.21	'	'
Price Range Two [Member]	'	'	'
Schedule Of Stock Option Activity [Line Items]	'	'	'
Exercise price range, lower range limit	$16.01	'	'
Exercise price range, upper range limit	$20	'	'
Number of Options Outstanding	2,845	'	'
Weighted Average Remaining Contractual Life	'10 months 24 days	'	'
Weighted Average Exercise Price	$17.74	'	'
Number of Options Exercisable	2,845	'	'
Options Exercisable, Weighted Average Exercise Price	$17.74	'	'
Price Range Three [Member]	'	'	'
Schedule Of Stock Option Activity [Line Items]	'	'	'
Exercise price range, lower range limit	$32.01	'	'
Exercise price range, upper range limit	$36	'	'
Number of Options Outstanding	51,863	'	'
Weighted Average Remaining Contractual Life	'1 year 4 months 24 days	'	'
Weighted Average Exercise Price	$34.87	'	'
Number of Options Exercisable	51,863	'	'
Options Exercisable, Weighted Average Exercise Price	$34.87	'	'
Price Range Four [Member]	'	'	'
Schedule Of Stock Option Activity [Line Items]	'	'	'
Exercise price range, lower range limit	$40.01	'	'
Exercise price range, upper range limit	$44	'	'
Number of Options Outstanding	3,468	'	'
Weighted Average Remaining Contractual Life	'9 months 18 days	'	'
Weighted Average Exercise Price	$40.28	'	'
Number of Options Exercisable	3,468	'	'
Options Exercisable, Weighted Average Exercise Price	$40.28	'	'

StockBased_Compensation_Summar3

Stock-Based Compensation - Summary of Information Related to Options Outstanding (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share Based Compensation Shares Authorized Under Stock Option Plans Information Related To Option Outstanding [Abstract]	'	'	'
Minimum exercise price	$6.21	$6.21	$6.21
Maximum exercise price	$40.28	$40.28	$40.28
Average remaining option term	'1 year 4 months 24 days	'1 year 10 months 24 days	'2 years 9 months 18 days

StockBased_Compensation_Summar4

Stock-Based Compensation - Summary of Stock Option Grants and Exercises (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share Based Compensation Arrangement By Share Based Payment Award Options Information Related To Stock Option Grants And Exercises [Abstract]	'	'	'
Aggregate intrinsic value of stock options exercised	$408,000	$307,000	$26,000
Cash received from stock option exercises	289,000	227,000	55,000
Tax benefit realized from stock option exercises	$0	$0	$0
Weighted average per share fair value of stock options granted	'	'	'

Related_Parties_Additional_Inf

Related Parties - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Related Party Transactions [Abstract]	'	'	'
Loan commitments to directors and executive officers	$7,800,000	$2,900,000	'
Loan outstanding	6,884,000	1,418,000	1,242,000
Related party deposits and repurchase agreements total	$3,900,000	$3,300,000	'

Related_Parties_Loans_Outstand

Related Parties - Loans Outstanding to Directors and Executive Officers at Beginning of Period and End of Period, Including Activity During Period (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Related Party Transactions [Abstract]	'	'
Beginning balance	$1,418,000	$1,242,000
New loans	6,309,000	324,000
Repayments	-252,000	-110,000
Adjustments	-591,000	-38,000
Ending balance	$6,884,000	$1,418,000

Commitments_and_OffBalance_She

Commitments and Off-Balance Sheet Risk - Maximum Exposure to Credit Losses for Loan Commitments and Standby Letters of Credit Outstanding (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]	'	'
Contractual amounts of financial instruments with off-balance sheet risk	$374,543,000	$334,768,000
Commercial unused lines of credit [Member]	'	'
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]	'	'
Contractual amounts of financial instruments with off-balance sheet risk	257,937,000	222,237,000
Unused lines of credit secured by 1 - 4 family residential properties [Member]	'	'
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]	'	'
Contractual amounts of financial instruments with off-balance sheet risk	23,429,000	24,250,000
Credit card unused lines of credit [Member]	'	'
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]	'	'
Contractual amounts of financial instruments with off-balance sheet risk	9,013,000	8,512,000
Other consumer unused lines of credit [Member]	'	'
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]	'	'
Contractual amounts of financial instruments with off-balance sheet risk	5,695,000	4,613,000
Commitments to make loans [Member]	'	'
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]	'	'
Contractual amounts of financial instruments with off-balance sheet risk	58,799,000	64,565,000
Standby letters of credit [Member]	'	'
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]	'	'
Contractual amounts of financial instruments with off-balance sheet risk	$19,670,000	$10,591,000

Commitments_and_OffBalance_She1

Commitments and Off-Balance Sheet Risk - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]	'	'
Line of credit facilities	'1 year	'
Libor rate period	'30 days	'
Fixed rate range of term debt secured by real estate, Maximum	4.00%	'
Fixed rate range of term debt secured by real estate, Maximum	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	'
Remaining amount of fees collected from customers relating to risk participation agreements associated with interest rate swap agreements, reflected as liabilities	$0.10	$0.10
Amount of federal reserve requirement	1.5	1.2
Interest rate swap agreement [Member]	'	'
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]	'	'
Notional amount of the underlying interest rate swap agreements, entered into by commercial loan customers with correspondent banks	17.9	'
Net fair value of interest rate swaps entered into by commercial loan customer's with correspondent banks	($2.30)	'
Minimum [Member]	'	'
Commitments Contingencies And Off Balance Sheet Arrangements [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%	'
Income recognition period for risk participation agreement fees collected from customers entering into interest rate swap agreements with correspondent banks	'4 years	'
Maximum [Member]	'	'
Commitments Contingencies And Off Balance Sheet Arrangements [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%	'
Income recognition period for risk participation agreement fees collected from customers entering into interest rate swap agreements with correspondent banks	'15 years	'

Commitments_and_OffBalance_She2

Commitments and Off-Balance Sheet Risk - Instruments Carried at Fair Value (Detail) (Standby letters of credit [Member], USD $)	Dec. 31, 2013	Dec. 31, 2012
Standby letters of credit [Member]	'	'
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]	'	'
Contract Amount	$19,670,000	$10,591,000
Carrying Value	$148,000	$218,000

Benefit_Plans_Additional_Infor

Benefit Plans - Additional Information (Detail) (USD $)	1 Months Ended			12 Months Ended			1 Months Ended
In Millions, except Share data, unless otherwise specified	Oct. 31, 2012	Jan. 31, 2012	31-May-11	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 31, 2014
							Subsequent Event [Member]
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'	'	'	'
Percentage of matching contribution to benefits plan	4.00%	3.00%	2.00%	'	'	'	4.25%
Expenses on contribution charged	'	'	'	$0.50	$0.40	$0.20	'
Number of shares of common stock issuable under employee stock purchase plan of 2002	'	'	'	55,000	'	'	'
Number of shares issued under employee stock purchase plan	'	'	'	1,098	2,400	4,726	'
Number of shares available under employee stock purchase plan	'	'	'	3,942	'	'	'

Hedging_Activities_Additional_

Hedging Activities - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Feb. 29, 2012	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2011
Derivative Instruments and Hedging Activities Disclosures [Line Items]	'	'	'	'
Trust preferred securities	$32	'	'	'
Bank payment on corresponding notional amount fixed rate/ Basis for determining strike rate on purchased interest rate cap	'	'30-Day Libor rate	'	'
Interest rate swap agreement maturity date	'2018-01	'	'	'
Fair value of Interest rate swap, record as liability	'	0.3	1.1	'
Notional amount of sold interest rate cap	'	'	'	100
Strike rate of sold interest rate cap in basis points above strike rate on purchased interest rate cap	'	'	'	1.25%
Payments made under interest rate cap contracts	'	0	'	'
Interest rate swap agreement [Member]	'	'	'	'
Derivative Instruments and Hedging Activities Disclosures [Line Items]	'	'	'	'
Bank payment on corresponding notional amount fixed rate/ Basis for determining strike rate on purchased interest rate cap	'	'90-Day Libor Rate	'	'
Trust preferred securities interest rate index	'	'90-Day Libor Rate	'	'
Fixed spread added to the variable rate on our trust preferred securities	218	'	'	'
Notional amounts of interest rate swap agreement and purchased interest rate cap	32	'	'	'
Interest rate cap contracts [Member]	'	'	'	'
Derivative Instruments and Hedging Activities Disclosures [Line Items]	'	'	'	'
Notional amounts of interest rate swap agreement and purchased interest rate cap	'	'	'	$100

Recovered_Sheet11

Fair Values of Financial Instruments - Carrying Amount, Estimated Fair Value and Level Within Fair Value Hierarchy of Financial Instruments (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Financial assets	'	'
Securities available for sale	$131,178,000	$138,314,000
Carrying Amount [Member]	'	'
Financial assets	'	'
Securities available for sale	131,178,000	138,314,000
Federal Home Loan Bank stock	11,961,000	11,961,000
Carrying Amount [Member] | Level 1 [Member]	'	'
Financial assets	'	'
Cash	1,464,000	1,576,000
Carrying Amount [Member] | Level 2 [Member]	'	'
Financial assets	'	'
Cash equivalents	145,501,000	134,427,000
Bank owned life insurance	51,377,000	50,048,000
Accrued interest receivable	3,649,000	3,874,000
Financial liabilities	'	'
Deposits	1,118,911,000	1,135,204,000
Securities sold under agreements to repurchase	69,305,000	64,765,000
Federal Home Loan Bank advances	45,000,000	35,000,000
Subordinated debentures	32,990,000	32,990,000
Accrued interest payable	2,041,000	2,314,000
Carrying Amount [Member] | Level 3 [Member]	'	'
Financial assets	'	'
Loans, net	1,030,422,000	1,012,512,000
Carrying Amount [Member] | Interest rate swap agreement [Member]	'	'
Financial liabilities	'	'
Interest rate swap	264,000	1,113,000
Fair Value [Member]	'	'
Financial assets	'	'
Securities available for sale	131,178,000	138,314,000
Federal Home Loan Bank stock	11,961,000	11,961,000
Fair Value [Member] | Level 1 [Member]	'	'
Financial assets	'	'
Cash	1,464,000	1,576,000
Fair Value [Member] | Level 2 [Member]	'	'
Financial assets	'	'
Cash equivalents	145,501,000	134,427,000
Bank owned life insurance	51,377,000	50,048,000
Accrued interest receivable	3,649,000	3,874,000
Financial liabilities	'	'
Deposits	1,120,576,000	1,135,614,000
Securities sold under agreements to repurchase	69,305,000	64,765,000
Federal Home Loan Bank advances	45,139,000	35,000,000
Subordinated debentures	32,974,000	32,943,000
Accrued interest payable	2,041,000	2,314,000
Fair Value [Member] | Level 3 [Member]	'	'
Financial assets	'	'
Loans, net	1,027,300,000	1,004,541,000
Fair Value [Member] | Interest rate swap agreement [Member]	'	'
Financial liabilities	'	'
Interest rate swap	$264,000	$1,113,000

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument Fair Value Carrying Value [Abstract]	'	'
Recorded cost of mortgage loans held for sale	$1.10	$3.50
Transfers in or out of Level 1, Level 2 or Level 3 of fair value hierarchy	$0	$0

Fair_Value_Measurements_Assets

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	$131,178,000	$138,314,000
U.S. Government agency debt obligations [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	98,477,000	79,098,000
Mortgage-backed securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	13,558,000	21,996,000
Michigan Strategic Fund bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	0	11,255,000
Municipal general obligation bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	16,872,000	22,743,000
Mutual funds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	1,355,000	1,405,000
Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Assets and liabilities measured at fair value on recurring basis	130,914,000	137,201,000
Fair Value, Measurements, Recurring [Member] | U.S. Government agency debt obligations [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	98,477,000	79,098,000
Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	13,558,000	21,996,000
Fair Value, Measurements, Recurring [Member] | Michigan Strategic Fund bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	'	11,255,000
Fair Value, Measurements, Recurring [Member] | Municipal general obligation bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	16,872,000	22,743,000
Fair Value, Measurements, Recurring [Member] | Municipal revenue bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	916,000	1,817,000
Fair Value, Measurements, Recurring [Member] | Mutual funds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	1,355,000	1,405,000
Fair Value, Measurements, Recurring [Member] | Interest rate swap agreement [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivatives	-264,000	-1,113,000
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Assets and liabilities measured at fair value on recurring basis	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | U.S. Government agency debt obligations [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Mortgage-backed securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Michigan Strategic Fund bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	'	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Municipal general obligation bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Municipal revenue bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Mutual funds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Interest rate swap agreement [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivatives	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Assets and liabilities measured at fair value on recurring basis	130,914,000	137,201,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. Government agency debt obligations [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	98,477,000	79,098,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Mortgage-backed securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	13,558,000	21,996,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Michigan Strategic Fund bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	'	11,255,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Municipal general obligation bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	16,872,000	22,743,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Municipal revenue bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	916,000	1,817,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Mutual funds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	1,355,000	1,405,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Interest rate swap agreement [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivatives	-264,000	-1,113,000
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Assets and liabilities measured at fair value on recurring basis	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | U.S. Government agency debt obligations [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Mortgage-backed securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Michigan Strategic Fund bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	'	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Municipal general obligation bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Municipal revenue bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Mutual funds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available for sale securities/Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Interest rate swap agreement [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivatives	$0	$0

Fair_Value_Measurements_Assets1

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Detail) (Fair Value, Measurements, Nonrecurring [Member], USD $)	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Impaired loans	$23,405,000	$34,406,000
Foreclosed assets	2,851,000	6,970,000
Total	26,256,000	41,376,000
Level 1 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Impaired loans	0	0
Foreclosed assets	0	0
Total	0	0
Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Impaired loans	0	0
Foreclosed assets	0	0
Total	0	0
Level 3 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Impaired loans	23,405,000	34,406,000
Foreclosed assets	2,851,000	6,970,000
Total	$26,256,000	$41,376,000

Earnings_Per_Share_Earnings_Pe

Earnings Per Share - Earnings Per Share (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Basic	'	'	'	'	'	'	'	'	'	'	'
Net income attributable to common shares	$5,163,000	$3,453,000	$4,016,000	$4,400,000	$3,049,000	$2,616,000	$3,288,000	$2,552,000	$17,033,000	$11,505,000	$36,142,000
Weighted average common shares outstanding	'	'	'	'	'	'	'	'	8,710,677	8,625,198	8,602,845
Basic earnings per common share	$0.59	$0.40	$0.46	$0.51	$0.35	$0.30	$0.38	$0.30	$1.96	$1.33	$4.20
Diluted	'	'	'	'	'	'	'	'	'	'	'
Net income attributable to common shares	'	'	'	'	'	'	'	'	$17,033,000	$11,505,000	$36,142,000
Weighted average common shares outstanding for basic earnings per common share	'	'	'	'	'	'	'	'	8,710,677	8,625,198	8,602,845
Add: Dilutive effects of share-based awards	'	'	'	'	'	'	'	'	14,031	224,429	275,335
Average shares and dilutive potential common shares	'	'	'	'	'	'	'	'	8,724,708	8,849,627	8,878,180
Diluted earnings per common share	$0.59	$0.40	$0.46	$0.50	$0.35	$0.30	$0.36	$0.28	$1.95	$1.30	$4.07

Earnings_Per_Share_Additional_

Earnings Per Share - Additional Information (Detail) (Stock Options [Member])	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock Options [Member]	'	'	'
Earnings Per Common Share [Line Items]	'	'	'
Antidilutive stock options not included in determining dilutive earnings per share	55,000	132,000	167,000

Subordinated_Debentures_Additi

Subordinated Debentures - Additional Information (Detail) (USD $)	1 Months Ended			0 Months Ended
	Sep. 30, 2004	Sep. 16, 2004	Dec. 10, 2004	Sep. 16, 2004	Sep. 16, 2004	Dec. 10, 2004	Dec. 10, 2004
		Series A Note [Member]	Series B Notes [Member]	Series A Preferred Stock [Member]	Common Class A [Member]	Series B Preferred Stock [Member]	Common Class B [Member]
		Mercantile Bank Capital Trust [Member]	Mercantile Bank Capital Trust [Member]		Mercantile Bank Capital Trust [Member]		Mercantile Bank Capital Trust [Member]
Subordinated Borrowing [Line Items]	'	'	'	'	'	'	'
Series A and B Preferred Securities sold in a private sale	'	'	'	$16,000,000	'	$16,000,000	'
Series A and B Common Securities sold by trust to Mercantile	'	'	'	'	495,000	'	495,000
Proceeds of series A preferred securities and series A common securities used to purchase of series A floating rate notes	'	16,495,000	16,495,000	'	'	'	'
Preferred Securities percentage	9.60%	'	'	'	'	'	'
Proceeds of Series A floating rate notes to finance redemption	$16,000,000	'	'	'	'	'	'

Regulatory_Matters_Summary_of_

Regulatory Matters - Summary of Actual Capital Levels and Minimum Levels (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Consolidated [Member]	'	'
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]	'	'
Total capital (to risk weighted assets), Actual Amount	$193,925	$173,323
Tier 1 capital (to risk weighted assets), Actual Amount	178,598	158,349
Tier 1 capital (to average assets), Actual Amount	178,598	158,349
Total capital (to risk weighted assets), Actual Ratio	15.90%	14.60%
Tier 1 capital (to risk weighted assets), Actual Ratio	14.70%	13.40%
Tier 1 capital (to average assets), Actual Ratio	12.50%	11.30%
Total capital (to risk weighted assets), Minimum Amount Required for Capital Adequacy Purposes	97,498	94,738
Tier 1 capital (to risk weighted assets), Minimum Amount Required for Capital Adequacy Purposes	48,749	47,369
Tier 1 capital (to average assets), Minimum Amount Required for Capital Adequacy Purposes	57,006	55,995
Total capital (to risk weighted assets), Minimum Ratio Required for Capital Adequacy Purposes	8.00%	8.00%
Tier 1 capital (to risk weighted assets), Minimum Ratio Required for Capital Adequacy Purposes	4.00%	4.00%
Tier 1 capital (to average assets), Minimum Ratio Required for Capital Adequacy Purposes	4.00%	4.00%
Total capital (to risk weighted assets), Minimum Amount Required to be Well Capitalized Under Prompt Corrective Action Regulations	'	'
Tier 1 capital (to risk weighted assets), Minimum Amount Required to be Well Capitalized Under Prompt Corrective Action Regulations	'	'
Tier 1 capital (to average assets), Minimum Amount Required to be Well Capitalized Under Prompt Corrective Action Regulations	'	'
Total capital (to risk weighted assets), Minimum Ratio Required to be Well Capitalized Under Prompt Corrective Action Regulations	'	'
Tier 1 capital (to risk weighted assets), Minimum Ratio Required to be Well Capitalized Under Prompt Corrective Action Regulations	'	'
Tier 1 capital (to average assets), Minimum Ratio Required to be Well Capitalized Under Prompt Corrective Action Regulations	'	'
Bank [Member]	'	'
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]	'	'
Total capital (to risk weighted assets), Actual Amount	190,493	173,828
Tier 1 capital (to risk weighted assets), Actual Amount	175,192	158,871
Tier 1 capital (to average assets), Actual Amount	175,192	158,871
Total capital (to risk weighted assets), Actual Ratio	15.70%	14.70%
Tier 1 capital (to risk weighted assets), Actual Ratio	14.40%	13.40%
Tier 1 capital (to average assets), Actual Ratio	12.30%	11.40%
Total capital (to risk weighted assets), Minimum Amount Required for Capital Adequacy Purposes	97,329	94,629
Tier 1 capital (to risk weighted assets), Minimum Amount Required for Capital Adequacy Purposes	48,665	47,315
Tier 1 capital (to average assets), Minimum Amount Required for Capital Adequacy Purposes	56,860	55,937
Total capital (to risk weighted assets), Minimum Ratio Required for Capital Adequacy Purposes	8.00%	8.00%
Tier 1 capital (to risk weighted assets), Minimum Ratio Required for Capital Adequacy Purposes	4.00%	4.00%
Tier 1 capital (to average assets), Minimum Ratio Required for Capital Adequacy Purposes	4.00%	4.00%
Total capital (to risk weighted assets), Minimum Amount Required to be Well Capitalized Under Prompt Corrective Action Regulations	121,662	118,286
Tier 1 capital (to risk weighted assets), Minimum Amount Required to be Well Capitalized Under Prompt Corrective Action Regulations	72,997	70,972
Tier 1 capital (to average assets), Minimum Amount Required to be Well Capitalized Under Prompt Corrective Action Regulations	$71,075	$69,922
Total capital (to risk weighted assets), Minimum Ratio Required to be Well Capitalized Under Prompt Corrective Action Regulations	10.00%	10.00%
Tier 1 capital (to risk weighted assets), Minimum Ratio Required to be Well Capitalized Under Prompt Corrective Action Regulations	6.00%	6.00%
Tier 1 capital (to average assets), Minimum Ratio Required to be Well Capitalized Under Prompt Corrective Action Regulations	5.00%	5.00%

Regulatory_Matters_Additional_

Regulatory Matters - Additional Information (Detail) (USD $)

0 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

Dec. 10, 2013

Sep. 10, 2013

Jun. 10, 2013

Mar. 08, 2013

Dec. 10, 2012

Oct. 31, 2013

Jul. 31, 2013

Apr. 30, 2013

Jan. 31, 2013

Oct. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2009

Jan. 31, 2014

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Subsequent Event [Member]

Installment One FY Two Thousand Thirteen [Member]

Installment Two FY Two Thousand Thirteen [Member]

Installment Three FY Two Thousand Thirteen [Member]

Installment Four FY Two Thousand Thirteen [Member]

Installment Five Fy Two Thousand Thirteen [Member]

Installment Six Fy Two Thousand Thirteen [Member]

Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum amount of dividends distributed by bank to holding company without prior regulatory approval

'

'

'

'

'

'

'

'

'

'

$31,400,000

'

'

'

'

'

'

'

'

'

Cash dividend on common stock

$0.12

$0.12

$0.11

$0.10

$0.09

'

'

'

'

'

$0.45

$0.09

'

'

'

'

'

'

'

'

Cash dividend declared on common stock

'

'

'

'

'

$0.12

$0.12

$0.11

$0.10

$0.09

'

'

'

$0.12

'

'

'

'

'

'

Dividend declared date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

11-Oct-12

10-Jan-13

11-Apr-13

11-Jul-13

10-Oct-13

16-Jan-14

Dividend payable date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

10-Dec-12

8-Mar-13

10-Jun-13

10-Sep-13

10-Dec-13

10-Mar-14

Dividend payable date of record

'

'

'

'

'

'

'

'

'

'

'

'

'

'

9-Nov-12

8-Feb-13

10-May-13

9-Aug-13

8-Nov-13

10-Feb-14

Dividend suspended date

'

'

'

'

'

'

'

'

'

'

1-Apr-10

'

'

'

'

'

'

'

'

'

Trust preferred securities

'

'

'

'

'

'

'

'

'

'

32,000,000

32,000,000

'

'

'

'

'

'

'

'

Aggregate amount of restricted core elements allowed in Tier 1 capital

'

'

'

'

'

'

'

'

'

'

25.00%

'

'

'

'

'

'

'

'

'

Trusted preferred securities issued date

'

'

'

'

'

'

'

'

'

'

'Before May 19, 2010

'

'

'

'

'

'

'

'

'

Maximum level of consolidated aggregate assets allowing for inclusion of trust preferred securities in Tier Capital under Dodd-Frank Act

'

'

'

'

'

'

'

'

'

'

'

'

$15,000,000,000

'

'

'

'

'

'

'

USTreasury_Capital_Purchase_Pr

U.S.Treasury Capital Purchase Program Participation - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended		12 Months Ended
	15-May-09	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Class of Warrant or Right [Line Items]	'	'	'	'	'	'
Sale of preferred stock and a warrant for common stock	$21,000,000	'	'	'	'	'
Number of cumulative perpetual preferred stock shares	21,000	'	'	'	'	'
Liquidation value of cumulative perpetual preferred stock	$1,000	'	'	'	'	'
Number of common stock shares available to U.S. Treasury under warrant issued	616,438	'	'	'	'	'
Preferred stock, par value	'	'	'	'	'	'
Rate of cumulative dividends for the first five years	5.00%	'	'	'	'	'
Rate of cumulative dividends for the remaining period	9.00%	'	'	'	'	'
Period of common stock warrant	'	'	'	'10 years	'	'
Exercise price of common stock warrant	5.11	'	'	'	'	'
Discount rate	12.00%	'	'	'	'	'
Estimated fair value	15,500,000	'	'	'	'	'
Fair value of common stock warrant	900,000	'	'	'	'	'
Aggregate fair value for preferred stock and the common stock warrant	16,400,000	'	'	'	'	'
Aggregate attributable to the preferred stock	94.60%	'	'	'	'	'
Aggregate attributable to the common stock warrants	5.40%	'	'	'	'	'
Issuance amount allocated to preferred stock	19,900,000	'	'	'	'	'
Issuance amount allocated to common stock warrant	1,100,000	'	'	'	'	'
Discount on the preferred stock	1,300,000	'	'	'	'	'
Period of reduction in net income available to common shareholders	'5 years	'	'	'	'	'
Reduction from retained earnings resulting from accelerated discount on preferred Stock	'	'	600,000	'	'	'
Reduction in shareholders' equity resulting from repurchase of warrant	'	7,500,000	'	'	'	'
Repurchase price of warrant	'	'	'	0	7,465,000	0
Minimum [Member]	'	'	'	'	'	'
Class of Warrant or Right [Line Items]	'	'	'	'	'	'
Reduction in net income attributable to common shareholders due to accretion of preferred stock discount	200,000	'	'	'	'	'
Maximum [Member]	'	'	'	'	'	'
Class of Warrant or Right [Line Items]	'	'	'	'	'	'
Reduction in net income attributable to common shareholders due to accretion of preferred stock discount	300,000	'	'	'	'	'
Stock warrant [Member]	'	'	'	'	'	'
Class of Warrant or Right [Line Items]	'	'	'	'	'	'
Expected dividend yield	1.00%	'	'	'	'	'
Risk-free interest rate	1.99%	'	'	'	'	'
Expected life	'5 years	'	'	'	'	'
Expected volatility	53.00%	'	'	'	'	'
Weighted average fair value	$3.92	'	'	'	'	'
Repurchase price of warrant	'	7,500,000	'	'	'	'
Preferred Stock [Member]	'	'	'	'	'	'
Class of Warrant or Right [Line Items]	'	'	'	'	'	'
Direct cost associated with transaction	200,000	'	'	'	'	'
Repurchase of Preferred Stock	'	'	$21,000,000	'	'	'

Recovered_Sheet12

Accumulated Other Comprehensive Income (Loss) - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Millions, unless otherwise specified
Statement Of Income And Comprehensive Income [Abstract]	'	'	'
Net unrealized gain (loss) on available for sale securities	($5.40)	$2.40	$3.30
Fair value of the interest rate swap	($0.20)	($0.70)	'

Recovered_Sheet13

Quarterly Financial Data (Unaudited) - Quarterly Financial Data (Unaudited) (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Interest Income	$15,373,000	$14,667,000	$13,992,000	$14,209,000	$14,666,000	$14,768,000	$14,930,000	$15,553,000	$58,242,000	$59,917,000	$71,069,000
Net Interest Income	12,695,000	11,994,000	11,312,000	11,454,000	11,737,000	11,584,000	11,511,000	11,869,000	47,456,000	46,701,000	51,237,000
Net income attributable to common shares	$5,163,000	$3,453,000	$4,016,000	$4,400,000	$3,049,000	$2,616,000	$3,288,000	$2,552,000	$17,033,000	$11,505,000	$36,142,000
Earnings per Share Basic	$0.59	$0.40	$0.46	$0.51	$0.35	$0.30	$0.38	$0.30	$1.96	$1.33	$4.20
Earnings per Share Diluted	$0.59	$0.40	$0.46	$0.50	$0.35	$0.30	$0.36	$0.28	$1.95	$1.30	$4.07

Recovered_Sheet14

Mercantile Bank Corporation (Parent Company Only) Condensed Financial Statements - Summary of Condensed Balance Sheets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
ASSETS	'	'	'	'
Other assets	$5,911,000	$15,310,000	'	'
Total assets	1,426,966,000	1,422,926,000	'	'
LIABILITIES AND SHAREHOLDERS' EQUITY	'	'	'	'
Liabilities	1,273,641,000	1,276,336,000	'	'
Subordinated debentures	32,990,000	32,990,000	'	'
Shareholders' equity	153,325,000	146,590,000	164,999,000	125,936,000
Total liabilities and shareholders' equity	1,426,966,000	1,422,926,000	'	'
Parent Company [Member]	'	'	'	'
ASSETS	'	'	'	'
Cash and cash equivalents	2,506,000	473,000	542,000	1,233,000
Investment in bank subsidiary	179,706,000	173,019,000	'	'
Other assets	4,740,000	7,433,000	'	'
Total assets	186,952,000	180,925,000	'	'
LIABILITIES AND SHAREHOLDERS' EQUITY	'	'	'	'
Liabilities	637,000	1,345,000	'	'
Subordinated debentures	32,990,000	32,990,000	'	'
Shareholders' equity	153,325,000	146,590,000	'	'
Total liabilities and shareholders' equity	$186,952,000	$180,925,000	'	'

Recovered_Sheet15

Mercantile Bank Corporation (Parent Company Only) Condensed Financial Statements - Summary of Condensed Statements of Income (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income	'	'	'	'	'	'	'	'	'	'	'
Interest and dividends from subsidiaries	$15,373,000	$14,667,000	$13,992,000	$14,209,000	$14,666,000	$14,768,000	$14,930,000	$15,553,000	$58,242,000	$59,917,000	$71,069,000
Expenses	'	'	'	'	'	'	'	'	'	'	'
Interest expense	'	'	'	'	'	'	'	'	10,786,000	13,216,000	19,832,000
Income before income tax expense (benefit) and equity in undistributed net income (loss) of subsidiary	'	'	'	'	'	'	'	'	25,125,000	18,171,000	10,124,000
Federal income tax benefit	'	'	'	'	'	'	'	'	8,092,000	5,636,000	-27,361,000
Net income	'	'	'	'	'	'	'	'	17,033,000	12,535,000	37,485,000
Preferred stock dividends and accretion	'	'	'	'	'	'	'	'	0	1,030,000	1,343,000
Net income attributable to common shares	5,163,000	3,453,000	4,016,000	4,400,000	3,049,000	2,616,000	3,288,000	2,552,000	17,033,000	11,505,000	36,142,000
Parent Company [Member]	'	'	'	'	'	'	'	'	'	'	'
Income	'	'	'	'	'	'	'	'	'	'	'
Interest and dividends from subsidiaries	'	'	'	'	'	'	'	'	5,516,000	32,532,000	4,974,000
Total income	'	'	'	'	'	'	'	'	5,516,000	32,532,000	4,974,000
Expenses	'	'	'	'	'	'	'	'	'	'	'
Interest expense	'	'	'	'	'	'	'	'	1,213,000	884,000	847,000
Other operating expenses	'	'	'	'	'	'	'	'	2,773,000	1,048,000	1,059,000
Total expenses	'	'	'	'	'	'	'	'	3,986,000	1,932,000	1,906,000
Income before income tax expense (benefit) and equity in undistributed net income (loss) of subsidiary	'	'	'	'	'	'	'	'	1,530,000	30,600,000	3,068,000
Federal income tax benefit	'	'	'	'	'	'	'	'	-1,042,000	-665,000	-2,272,000
Equity in undistributed net income (loss) of subsidiary	'	'	'	'	'	'	'	'	14,461,000	-18,730,000	32,145,000
Net income	'	'	'	'	'	'	'	'	17,033,000	12,535,000	37,485,000
Preferred stock dividends and accretion	'	'	'	'	'	'	'	'	0	1,030,000	1,343,000
Net income attributable to common shares	'	'	'	'	'	'	'	'	$17,033,000	$11,505,000	$36,142,000

Mercantile_Bank_Corporation_Pa2

Mercantile Bank Corporation (Parent Company Only) Condensed Financial Statements - Summary of condensed statements of Cash Flows (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities	'	'	'
Net income	$17,033,000	$12,535,000	$37,485,000
Adjustments to reconcile net income to net cash from (for) operating activities:	'	'	'
Stock-based compensation expense	473,000	54,000	61,000
Change in other assets	8,465,000	-1,805,000	2,771,000
Change in other liabilities	-269,000	2,257,000	-1,187,000
Net cash from operating activities	28,507,000	17,021,000	22,506,000
Cash flows from investing activities	'	'	'
Net cash for investing activities	-12,419,000	66,730,000	227,722,000
Cash flows from financing activities	'	'	'
Repurchase of preferred stock	0	-21,000,000	0
Repurchase of common stock warrant	0	-7,465,000	0
Stock option exercises, net of cashless exercises	289,000	227,000	55,000
Employee stock purchase plan	19,000	39,000	42,000
Dividend reinvestment plan	33,000	14,000	6,000
Cash dividends on preferred stock	0	-496,000	-1,620,000
Cash dividends on common stock	-3,889,000	-774,000	0
Net cash for financing activities	-5,126,000	-24,120,000	-238,054,000
Net change in cash and cash equivalents	10,962,000	59,631,000	12,174,000
Parent Company [Member]	'	'	'
Cash flows from operating activities	'	'	'
Net income	17,033,000	12,535,000	37,485,000
Adjustments to reconcile net income to net cash from (for) operating activities:	'	'	'
Equity in undistributed (income) loss of subsidiary	-14,461,000	18,730,000	-32,145,000
Stock-based compensation expense	473,000	54,000	61,000
Change in other assets	3,244,000	-3,006,000	-3,619,000
Change in other liabilities	-708,000	1,073,000	-956,000
Net cash from operating activities	5,581,000	29,386,000	826,000
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	-21,000,000	0
Repurchase of common stock warrant	0	-7,465,000	0
Stock option exercises, net of cashless exercises	289,000	227,000	55,000
Employee stock purchase plan	19,000	39,000	42,000
Dividend reinvestment plan	33,000	14,000	6,000
Cash dividends on preferred stock	0	-496,000	-1,620,000
Cash dividends on common stock	-3,889,000	-774,000	0
Net cash for financing activities	-3,548,000	-29,455,000	-1,517,000
Net change in cash and cash equivalents	2,033,000	-69,000	-691,000
Cash and cash equivalents at beginning of period	473,000	542,000	1,233,000
Cash and cash equivalents at end of period	$2,506,000	$473,000	$542,000