First Merchants (FRME) 10-K 27 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Feb. 20, 2015	Jun. 30, 2014
Document Documentand Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	FRME
Entity Registrant Name	FIRST MERCHANTS CORP
Entity Central Index Key	712534
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		37,680,604
Entity Public Float			$762,144

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
ASSETS
Cash and cash equivalents	$118,616	$109,434
Interest-bearing time deposits	47,520	55,069
Investment securities available for sale	549,543	536,201
Investment securities held to maturity (fair value of $647,723 and $560,847)	631,088	559,378
Loans held for sale	7,235	5,331
Loans	3,924,865	3,632,409
Less: Allowance for loan losses	-63,964	-67,870
Net loans	3,860,901	3,564,539
Premises and equipment	77,691	74,454
Federal Reserve and Federal Home Loan Bank stock	41,353	38,990
Interest receivable	19,984	18,672
Core deposit intangibles	16,031	13,818
Goodwill	202,724	188,948
Cash surrender value of life insurance	169,424	164,571
Other real estate owned	19,293	22,246
Tax asset, deferred and receivable	41,960	56,614
Other assets	20,764	28,997
TOTAL ASSETS	5,824,127	5,437,262
Deposits:
Noninterest-bearing	1,070,859	930,772
Interest-bearing	3,569,835	3,300,696
Total Deposits	4,640,694	4,231,468
Borrowings:
Federal funds purchased	15,381	125,645
Securities sold under repurchase agreements	124,539	148,672
Federal Home Loan Bank advances	145,264	122,140
Subordinated debentures and term loans	126,810	126,807
Total Borrowings	411,994	523,264
Interest payable	3,201	1,771
Other liabilities	41,411	45,836
Total Liabilities	5,097,300	4,802,339
COMMITMENTS AND CONTINGENT LIABILITIES
STOCKHOLDERS' EQUITY
Cumulative Preferred Stock, $1,000 par value, $1,000 liquidation value, Authorized 600 shares, Issued and outstanding - 125 shares	125	125
Common Stock - $.125 stated value, Authorized 50,000,000 shares, Issued and outstanding 37,669,948 and 35,921,761 shares	4,709	4,490
Additional paid-in capital	431,220	393,783
Retained earnings	292,403	242,935
Accumulated other comprehensive loss	-1,630	-6,410
Total Stockholders' Equity	726,827	634,923
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$5,824,127	$5,437,262

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]
Investment securities held to maturity	$647,723	$560,847
Common Stock, stated value (in dollars per share)	$0.13	$0.13
Common Stock, shares authorized	50,000,000	50,000,000
Common Stock, shares Issued	37,669,948	35,921,761
Common Stock, shares outstanding	37,669,948	35,921,761
Preferred Stock, par value (in dollars per share)	$1,000	$1,000
Preferred Stock, liquidation value (in dollars per share)	$1,000	$1,000
Preferred Stock, shares authorized	600	600
Preferred Stock, shares issued	125	125
Preferred Stock, shares outstanding	125	125

CONSOLIDATED_STATEMENTS_OF_INC

CONSOLIDATED STATEMENTS OF INCOME (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Loans receivable:
Taxable	$172,039	$142,752	$146,745
Tax-exempt	327	393	480
Investment securities:
Taxable	19,882	15,214	17,027
Tax-exempt	14,383	10,829	10,189
Deposits with financial institutions	124	158	100
Federal Reserve and Federal Home Loan Bank stock	2,124	1,488	1,408
Total Interest Income	208,879	170,834	175,949
INTEREST EXPENSE
Deposits	11,678	10,053	14,800
Federal funds purchased	177	102	69
Securities sold under repurchase agreements	529	787	907
Federal Home Loan Bank advances	2,842	2,096	2,624
Subordinated debentures, revolving credit lines and term loans	6,616	3,531	5,213
Total Interest Expense	21,842	16,569	23,613
NET INTEREST INCOME	187,037	154,265	152,336
Provision for loan losses	2,560	6,648	18,534
NET INTEREST INCOME AFTER PROVISION FOR LOAN LOSSES	184,477	147,617	133,802
OTHER INCOME
Service charges on deposit accounts	15,747	12,400	11,587
Fiduciary activities	8,966	8,594	7,891
Other customer fees	15,699	11,866	11,233
Commission income	7,411	7,141	6,224
Earnings on cash surrender value of life insurance	3,659	2,613	3,418
Net gains and fees on sales of loans	4,899	7,511	10,628
Net realized gains on sales of available for sale securities	3,581	487	2,389
Gain on FDIC modified whole bank transaction			9,124
Other income	5,705	4,197	1,808
Total Other Income	65,667	54,809	64,302
OTHER EXPENSES
Salaries and employee benefits	96,499	85,413	79,398
Net occupancy	13,831	10,291	10,186
Equipment	9,337	7,737	7,201
Marketing	3,464	2,236	2,158
Outside data processing fees	7,315	5,591	5,656
Printing and office supplies	1,565	1,340	1,169
Core deposit amortization	2,445	1,649	1,927
FDIC assessments	3,738	2,862	3,509
Other real estate owned and foreclosure expenses	8,043	6,661	8,178
Professional and other outside services	8,116	8,297	6,228
Other expenses	14,239	11,142	11,505
Total Other Expenses	168,592	143,219	137,115
INCOME BEFORE INCOME TAX	81,552	59,207	60,989
Income tax expense	21,390	14,677	15,867
NET INCOME	60,162	44,530	45,122
Preferred stock dividends		-2,380	-4,539
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$60,162	$42,150	$40,583
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS PER SHARE:
Basic EPS	$1.66	$1.42	$1.42
Diluted EPS	$1.65	$1.41	$1.41

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$60,162	$44,530	$45,122
Other comprehensive income (loss) net of tax:
Unrealized holding gain (loss) on securities available for sale arising during the period, net of tax of $8,001, $6,841, and $654	14,860	-12,705	1,214
Unrealized loss on securities transferred to held-to-maturity, net of tax of $0, $1,786, and $0		-3,316
Unrealized gain (loss) on securities available for sale for which a portion of an other than temporary impairment has been recognized in income, net of tax of $995, $767, and $56	1,847	1,425	-104
Unrealized gain (loss) on cash flow hedges arising during the period, net of tax of $1,397, $831, and $514	-2,599	1,543	-952
Reclassification adjustment for net losses (gains) included in net income net of tax of $760, $157, and $759	-1,410	291	-1,413
Defined benefit pension plans, net of tax of $4,264, $6,382, and $346
Net gain (loss) arising during period	-7,580	10,704	-577
Amortization of prior service cost	-338	1,147	-65
Period change	4,780	-911	-1,897
Comprehensive income	$64,942	$43,619	$43,225

CONSOLIDATED_STATEMENTS_OF_COM1

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Unrealized holding gain (loss) on securities available for sale arising during the period, income tax	$8,001	($6,841)	$654
Unrealized gain (loss) on securities transferred to held-to-maturity, tax		-1,786	0
Unrealized gain (loss) on securities available for sale for which a portion of an other than temporary impairment has been recognized in income, tax	-995	-767	56
Unrealized gains/(losses) arising during the period, tax	-1,397	831	-514
Reclassification adjustment for gains (losses) included in net income, tax	760	-157	759
Defined benefit pension plans gain (loss), tax	$4,264	($6,382)	$346

CONSOLIDATED_STATEMENT_OF_STOC

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (USD $)	Total	Preferred Stock	Common Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2011	$514,467,000	$90,908,000	$3,570,000	$254,874,000	$168,717,000	($3,602,000)
Beginning balance (in shares) at Dec. 31, 2011		90,908	28,559,707
Comprehensive Income
Net income	45,122,000				45,122,000
Other comprehensive income (loss), net of tax	-1,897,000					-1,897,000
Cash dividends on common stock	-2,903,000				-2,903,000
Cash dividends on preferred stock under small business lending fund	-4,539,000				-4,539,000
Share-based compensation (in shares)			86,325
Share-based compensation	1,492,000		11,000	1,481,000
Stock Issued under employee benefit plans (in shares)			41,867
Stock issued under employee benefit plans	449,000		5,000	444,000
Stock issued under dividend reinvestment and stock purchase plan (in shares)			15,709
Stock issued under dividend reinvestment and stock purchase plan	202,000		2,000	200,000
Stock options exercised (in shares)			10,500
Stock options exercised	78,000		1,000	77,000
Stock redeemed (in shares)			-21,492
Stock redeemed	-235,000		-2,000	-233,000
Ending balance at Dec. 31, 2012	552,236,000	90,908,000	3,587,000	256,843,000	206,397,000	-5,499,000
Ending balance (in shares) at Dec. 31, 2012		90,908	28,692,616
Comprehensive Income
Net income	44,530,000				44,530,000
Other comprehensive income (loss), net of tax	-911,000					-911,000
Cash dividends on common stock	-5,612,000				-5,612,000
Cash dividends on preferred stock under small business lending fund	-2,380,000				-2,380,000
Preferred stock redemption under small business lending fund (in shares)		-90,783
Preferred stock redemption under small business lending fund	-90,783,000	-90,783,000
Issuance of common stock related to acquisition (in shares)			7,079,457
Issuance of common stock related to acquisition	135,642,000		885,000	134,757,000
Share-based compensation (in shares)			116,978
Share-based compensation	1,773,000		15,000	1,758,000
Stock Issued under employee benefit plans (in shares)			33,451
Stock issued under employee benefit plans	479,000		4,000	475,000
Stock issued under dividend reinvestment and stock purchase plan (in shares)			18,449
Stock issued under dividend reinvestment and stock purchase plan	325,000		2,000	323,000
Stock options exercised (in shares)			13,750
Stock options exercised	115,000		2,000	113,000
Stock redeemed (in shares)			-32,940
Stock redeemed	-491,000		-5,000	-486,000
Ending balance at Dec. 31, 2013	634,923,000	125,000	4,490,000	393,783,000	242,935,000	-6,410,000
Ending balance (in shares) at Dec. 31, 2013		125	35,921,761
Comprehensive Income
Net income	60,162,000				60,162,000
Other comprehensive income (loss), net of tax	4,780,000					4,780,000
Cash dividends on common stock	-10,694,000				-10,694,000
Issuance of common stock related to acquisition (in shares)			1,574,298
Issuance of common stock related to acquisition	34,981,000		197,000	34,784,000
Share-based compensation (in shares)			132,446
Share-based compensation	2,177,000		17,000	2,160,000
Stock Issued under employee benefit plans (in shares)			26,547
Stock issued under employee benefit plans	478,000		3,000	475,000
Stock issued under dividend reinvestment and stock purchase plan (in shares)			24,556
Stock issued under dividend reinvestment and stock purchase plan	523,000		3,000	520,000
Stock options exercised (in shares)	41,249		41,249
Stock options exercised	564,000		5,000	559,000
Stock redeemed (in shares)			-50,909
Stock redeemed	-1,067,000		-6,000	-1,061,000
Ending balance at Dec. 31, 2014	$726,827,000	$125,000	$4,709,000	$431,220,000	$292,403,000	($1,630,000)
Ending balance (in shares) at Dec. 31, 2014		125	37,669,948

CONSOLIDATED_STATEMENT_OF_STOC1

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Stockholders' Equity [Abstract]
Cash dividends on common stock (in dollars per share)	$0.29	$0.18	$0.10

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Flow From Operating Activities:
Net income	$60,162	$44,530	$45,122
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	2,560	6,648	18,534
Depreciation and amortization	6,007	4,670	4,472
Change in deferred taxes	23,051	13,939	15,890
Share-based compensation	2,177	1,773	1,492
Tax benefit from stock options exercised	-60
Loans originated for sale	-222,892	-280,693	-393,565
Proceeds from sales of Loans	220,988	297,851	389,129
Net gain on acquisition			-9,124
Gains on sales of securities available for sale	-3,581	-487	-2,389
Change in interest receivable	-545	-535	1,884
Change in interest payable	1,332	-364	-1,451
Change in other receivable		110,032
Other adjustments	-13,359	-14,233	275
Net cash provided by operating activities	75,840	183,131	70,269
Cash Flows from Investing Activities:
Net change in interest-bearing deposits	24,075	196,753	14,408
Purchases of:
Securities available for sale	-110,936	-398,491	-139,555
Securities held to maturity	-142,988	-11,145	-4,262
Proceeds from sales of securities available for sale	126,575	25,222	52,350
Proceeds from maturities of:
Securities available for sale	68,339	93,273	112,141
Securities held to maturity	69,420	78,534	68,118
Change in Federal Reserve and Federal Home Loan Bank stock	-413	-17	246
Net change in loans	-170,109	-142,861	-123,036
Net cash and cash equivalents received (paid) in acquisition	-10,084	10,992	29,113
Proceeds from the sale of other real estate owned	14,241	12,346	4,428
Other adjustments	5,889	-2,768	-2,065
Net cash provided by (used in) investing activities	-125,991	-138,162	11,886
Net change in :
Demand and savings deposits	53,062	141,052	228,725
Certificates of deposit and other time deposits	127,740	-211,399	-142,906
Borrowings	678,290	295,537	138,127
Repayment of borrowings	-789,563	-163,838	-271,005
Cash dividends on common stock	-10,694	-5,612	-2,903
Cash dividends on preferred stock		-2,380	-4,539
Stock issued under employee benefit plans	478	479	449
Stock issued under dividend reinvestment and stock purchase plans	523	325	202
Stock options exercised	504	115	78
Tax benefit from stock options exercised	60
Cumulative preferred stock redeemed (SBLF)		-90,783
Stock redeemed	-1,067	-491	-235
Net cash provided by (used in) financing activities	59,333	-36,995	-54,007
Net Change in Cash and Cash Equivalents	9,182	7,974	28,148
Cash and Cash Equivalents, January 1	109,434	101,460	73,312
Cash and Cash Equivalents, December 31	118,616	109,434	101,460
Additional cash flow information:
Interest paid	20,412	16,639	24,697
Income tax paid	6,209	7,578	11,738
Loans transferred to other real estate owned	4,431	7,170	4,441
Fixed assets transferred to other real estate owned	297	461
Non-cash investing activities using trade date accounting	3,170	4,984	1,518
Liabilities assumed in conjunction with acquisitions
Fair value of assets acquired	280,725	1,132,231	128,923
Cash received (paid) in acquisition	-14,208		17,200
Net gain on acquisition			-9,124
Less: Common stock issued	34,981	135,642
Liabilities assumed	$231,536	$996,589	$136,999

Nature_of_Operations_and_Summa

Nature of Operations and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Nature of Operations and Summary of Significant Accounting Policies	NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	The accounting and reporting policies of First Merchants Corporation (the “Corporation”), and its principal wholly owned subsidiaries, First Merchants Bank, N.A. (the “Bank”), and First Merchants Insurance Services, Inc. operating as First Merchants Insurance Group (“FMIG”), conform to accounting principles generally accepted in the United States of America and reporting practices followed by the banking industry. The Bank also operates Lafayette Bank and Trust, Commerce National Bank, Community Bank of Noblesville and First Merchants Trust Company as divisions of First Merchants Bank, N.A.
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	The Corporation is a financial holding company whose principal activity is the ownership and management of the Bank and operates in a single significant business segment. The Bank operates under a national bank charter and provides full banking services. As a national bank, the Bank is subject to the regulation of the Office of Comptroller of the Currency (“OCC”) and the Federal Deposit Insurance Corporation (“FDIC”).  The OCC and the FDIC regulate or monitor virtually all areas of the Bank’s operations. The Bank must undergo regular on-site examinations by the OCC and FDIC and must submit periodic reports to both.
	The Bank generates commercial, mortgage, and consumer loans and receives deposits from customers located primarily in central and northwest Indiana, northeast Illinois and central Ohio counties. The Bank’s loans are generally secured by specific items of collateral, including real property, consumer assets and business assets.
	A brief description of current accounting practices and current valuation methodologies are presented below.
	CONSOLIDATION of the Corporation's financial statements include the accounts of the Corporation and all its subsidiaries, after elimination of all material intercompany transactions.
	BUSINESS COMBINATIONS are accounted for under the acquisition method of accounting. Under the acquisition method, assets and liabilities of the business acquired are recorded at their estimated fair values as of the date of acquisition with any excess of the cost of the acquisition over the fair value of the net tangible and intangible assets acquired recorded as goodwill. Results of operations of the acquired business are included in the income statement from the date of acquisition.
	AVAILABLE FOR SALE SECURITIES are recorded at fair value on a recurring basis with the unrealized gains and losses, net of applicable income taxes, recorded in other comprehensive income. Realized gains and losses are recorded in earnings and the prior fair value adjustments are reclassified within stockholders' equity. Gains and losses on sales of securities are determined on the specific-identification method. Amortization of premiums and accretion of discounts are recorded as interest income from securities.
	Available for sale and held to maturity securities are evaluated for other-than-temporary impairment (“OTTI”) at least on a quarterly basis, and more frequently when economic or market conditions warrant such an evaluation. The investment securities portfolio is evaluated for OTTI by segregating the portfolio into two general segments and applying the appropriate OTTI model. Investment securities are generally evaluated for OTTI under ASC 320. However, certain purchased beneficial interest, including certain non-agency government-sponsored mortgage-backed securities, asset-backed securities and collateralized debt obligations are evaluated using the model outlined in ASC 325-10.
	In determining OTTI under ASC 320, management considers many factors, including: (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near term prospects of the issuer, (3) whether the market decline was affected by macroeconomic conditions, and (4) whether the Corporation has the intent to sell the debt security or more likely than not will be required to sell the debt security before its anticipated recovery. The assessment of whether a decline exists that is other-than-temporary, involves a high degree of subjectivity and judgment and is based on the information available to management at a point in time.
	When the Corporation does not intend to sell a debt security, and it is more likely than not, the Corporation will not have to sell the security before recovery of its cost basis, it recognizes the credit component of an other-than-temporary impairment of a debt security in earnings and the remaining portion in other comprehensive income.  The amount of the total OTTI related to the credit loss is determined based on the present value of cash flows expected to be collected and is recognized in earnings. The amount of the total OTTI related to other factors has been recognized in other comprehensive income, net of applicable income taxes. The previous amortized cost basis less the OTTI recognized in earnings becomes the new amortized cost basis of the investment.
	If the intent is to sell or it is more likely than not that the Corporation will be required to sell the security before recovery of its amortized cost basis, less any recognized credit loss, the OTTI is recognized in earnings equal to the entire difference between the investment’s amortized cost basis, less any recognized credit loss, and its fair value at the balance sheet date.
	HELD TO MATURITY SECURITIES are classified as held to maturity when the Corporation has the positive intent and ability to hold the securities to maturity. Securities held to maturity are carried at amortized cost.  For held to maturity debt securities, the amount of an OTTI recorded in other comprehensive income for the noncredit portion of a previous other-than-temporary impairment is amortized prospectively over the remaining life of the security on the basis of the timing of future estimated cash flows of the security.
	LOANS HELD FOR SALE are carried at the principal amount outstanding. The carrying amount approximates fair value due to the short duration between origination and the date of sale.
	LOANS held in the Corporation’s portfolio are carried at the principal amount outstanding, net of unearned income. Certain non-accrual and substantially delinquent loans may be considered to be impaired. A loan is impaired when, based on current information or events, it is probable that the Bank will be unable to collect all amounts due (principal and interest) according to the contractual terms of the loan agreement. In applying the provisions of ASC 310, the Corporation considers its investment in one-to-four family residential loans and consumer installment loans to be homogeneous and therefore excluded from separate identification for evaluation of impairment. Interest income is accrued on the principal balances of loans, except for installment loans with add-on interest, for which a method that approximates the level yield method is used. The accrual of interest on impaired loans is discontinued when, in management’s opinion, the borrower may be unable to meet payments as they become due. When interest accrual is discontinued, all unpaid accrued interest is reversed against earnings when considered uncollectable. Interest income accrued in the prior year, if any, is charged to the allowance for loan losses. Interest income is subsequently recognized only to the extent cash payments are received and the loan is returned to accruing status. Certain loan fees and direct costs are being deferred and amortized as an adjustment of yield on the loans.
	Impaired loans are carried at the present value of estimated future cash flows using the loan’s existing rate, or the fair value of collateral if the loan is collateral dependent. A portion of the allowance for loan losses is allocated to impaired loans if the value of such loans is deemed to be less than the unpaid balance. If these allocations cause the allowance for loan losses to increase, such increase is reported as a component of the provision for loan losses. Loan losses are charged against the allowance when management believes the uncollectability of the loan is confirmed. The valuation would be considered Level 3, consisting of appraisals of underlying collateral and discounted cash flow analysis.
	Loan commitments and letters-of-credit generally have short-term, variable-rate features and contain clauses which limit the Bank’s exposure to changes in customer credit quality. Accordingly, their carrying values, which are immaterial at the respective balance sheet dates, are reasonable estimates of fair value.
	LOANS ACQUIRED IN BUSINESS COMBINATIONS with evidence of credit deterioration since origination and for which it is probable that all contractually required payments will not be collected are considered to be credit impaired. Evidence of credit quality deterioration as of purchase dates may include information such as past-due and nonaccrual status, borrower credit scores and recent loan to value percentages. Acquired credit-impaired loans are accounted for under the accounting guidance for loans and debt securities acquired with deteriorated credit quality (ASC 310-30). These loans are initially measured at fair value based upon expected cash flows without anticipation of prepayments and includes estimated future credit losses expected to be incurred over the life of the loans. As a result, related discounts are recognized subsequently through accretion based on the expected cash flows of the acquired loans. For purposes of applying ASC 310-30, loans acquired in business combinations are aggregated into pools of loans with common risk characteristics for the initial fair value measurement. Accordingly, allowances for credit losses related to these loans are not carried over and recorded at the acquisition date.
	The expected cash flows of the acquired loans in excess of the fair values recorded is referred to as the accretable yield and is recognized in interest income over the remaining estimated lives of the loans. The Corporation will continually evaluate the fair value of the loans including cash flows expected to be collected.
	ALLOWANCE FOR LOAN LOSSES is maintained to absorb losses inherent in the loan portfolio and is based on ongoing, quarterly assessments of the probable losses inherent in the loan portfolio. The allowance is increased by the provision for loan losses, which is charged against current operating results. Loan losses are charged against the allowance when management believes the uncollectability of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance. The Corporation’s strategy for credit risk management includes conservative credit policies and underwriting criteria for all loans, as well as an overall credit limit for each customer significantly below legal lending limits. The strategy also emphasizes diversification on a regional geographic, industry and customer level, regular credit quality reviews and management reviews of large credit exposures and loans experiencing deterioration of credit quality.
	The Corporation’s methodology for assessing the appropriateness of the allowance consists of three key elements – the determination of the appropriate reserves for specifically identified loans, probable losses estimated from historical loss rates, and probable losses resulting from economic, environmental, qualitative or other deterioration above and beyond what is reflected in the first two components of the allowance.
	Larger commercial loans that exhibit probable or observed credit weaknesses are subject to individual review. Where appropriate, reserves are allocated to individual loans based on management’s estimate of the borrower’s ability to repay the loan given the availability of collateral, other sources of cash flow and legal options available to the Corporation. Included in the review of individual loans are those that are impaired as provided in ASC 310. Any allowances for impaired loans are measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate or fair value of the underlying collateral. The Corporation evaluates the collectability of both principal and interest when assessing the need for a loss accrual. Historical loss rates are applied to other commercial loans not subject to specific reserve allocations.
	The historical allocation for commercial loans graded pass are established by loan segments using loss rates based on the Corporation’s migration analysis. This migration analysis shows the loss rates for each segment of loans based on the loan grades at the beginning of the twelve month period. This loss rate is then applied to the current portfolio of loans in each respective loan segment.
	Homogenous loans, such as consumer installment and residential mortgage loans, are not individually risk graded. Reserves are established for each segment of loans using loss rates based on charge offs for the same period as the migration analysis used for commercial loans.
	Historical loss allocations for commercial and consumer loans may be adjusted for significant factors that, in management’s judgment, reflect the impact of any current conditions on loss recognition. Factors which management considers in the analysis include the effects of the national and local economies, trends in loan growth and charge-off rates, changes in mix, concentration of loans in specific industries, asset quality trends (delinquencies, charge offs and non-accrual loans), risk management and loan administration, changes in the internal lending policies and credit standards, examination results from bank regulatory agencies and the Corporation’s internal loan review.
	PENSION benefits are provided to the Corporation’s employees. Its accounting policies related to pensions and other post retirement benefits reflect the guidance in ASC 715, Compensation – Retirement Benefits. The Corporation does not consolidate the assets and liabilities associated with the pension plan. Instead, the Corporation recognizes the funded status of the plan in the consolidated balance sheets. The measurement of the funded status and the annual pension expense involves actuarial and economic assumptions. Various statistical and other factors, which attempt to anticipate future events, are used in calculating the expense and liabilities related to the plans. Key factors include assumptions on the expected rates of return on plan assets, discount rates, expected rates of salary increases and health care costs and trends. The Corporation considers market conditions, including changes in investment returns and interest rates in making these assumptions. The primary assumptions used in determining the Corporation’s pension and post retirement benefit obligations and related expenses are presented in Note 21. PENSION AND OTHER POST RETIREMENT BENEFIT PLANS, in the Notes to Consolidated Financial Statements included as Item 8 of this Annual Report on Form 10-K.
	PREMISES AND EQUIPMENT is carried at cost net of accumulated depreciation. Depreciation is computed using the straight-line and declining balance methods based on the estimated useful lives of the assets ranging from three to forty years. Maintenance and repairs are expensed as incurred, while major additions and improvements, which extend the useful life, are capitalized. Gains and losses on dispositions are included in current operations.
	FEDERAL RESERVE AND FEDERAL HOME LOAN BANK STOCK are required investments for institutions that are members of the Federal Reserve Bank (“FRB”) and Federal Home Loan Bank systems. The required investment in the common stock is based on a predetermined formula based on the level of borrowings and other factors. These investments are carried at cost, classified as a restricted security and periodically evaluated for impairment based on ultimate recovery of par value. Both cash and stock dividends are reported as income.
	INTANGIBLE ASSETS that are subject to amortization, including core deposit intangibles, are being amortized on both the straight-line and accelerated basis over three to twenty years. Intangible assets are periodically evaluated as to the recoverability of their carrying value.
	GOODWILL is maintained by applying the provisions of ASC 350. For purchase acquisitions, the Corporation is required to record the assets acquired, including identified intangible assets, and the liabilities assumed at their fair value, which in many instances involves estimates based on third party valuations, such as appraisals, or internal valuations based on discounted cash flow analysis or other valuation techniques that may include estimates of attrition, inflation, asset growth rates or other relevant factors. In addition, the determination of the useful lives for which an intangible asset will be amortized is subjective.
	Under ASC 350, Intangibles – Goodwill and Other, the Corporation is required to evaluate goodwill for impairment on an annual basis, as well as on an interim basis, if events or changes indicate that the asset may be impaired, indicating that the carrying value may not be recoverable. The Corporation has historically elected to test for goodwill impairment as of October 1 of each year and has determined that no impairment exists.
	BANK OWNED LIFE INSURANCE has been purchased on certain employees and directors of the Corporation. The Corporation records the life insurance at the amount that can be realized under the insurance contract at the balance sheet date, which is the cash surrender value adjusted for other charges or amounts due that are probable at settlement.
	OTHER REAL ESTATE OWNED consists of assets acquired through, or in lieu of, loan foreclosure and are held for sale. They are initially recorded at fair value less cost to sell at the date of foreclosure, establishing a new cost basis.  Subsequent to foreclosure, valuations are periodically performed by management and the assets are carried at the lower of carrying amount or fair value less cost to sell.  Revenue and expenses from operations and changes in the valuation are included in net income or expense from foreclosed assets. Other real estate owned also includes bank premises qualifying as held for sale. Bank premises are transferred at the lower of carrying value or fair value less cost to sell.
	DERIVATIVE INSTRUMENTS are carried at the fair value of the derivatives and reflects the estimated amounts that would have been received to terminate these contracts at the reporting date based upon pricing or valuation models applied to current market information.
	As part of the asset/liability management program, the Corporation will utilize, from time to time, interest rate floors, caps or swaps to reduce its sensitivity to interest rate fluctuations. These are derivative instruments, which are recorded as assets or liabilities in the consolidated balance sheets at fair value. Changes in the fair values of derivatives are reported in the consolidated statements of operations or other comprehensive income (“OCI”) depending on the use of the derivative and whether the instrument qualifies for hedge accounting. The key criterion for the hedge accounting is that the hedged relationship must be highly effective in achieving offsetting changes in those cash flows that are attributable to the hedged risk, both at inception of the hedge and on an ongoing basis.
	Derivatives that qualify for the hedge accounting treatment are designated as either: a hedge of the fair value of the recognized asset or liability or of an unrecognized firm commitment (a fair value hedge) or a hedge of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (a cash flow hedge). To date, the Corporation has only entered into a cash flow hedge. For cash flow hedges, changes in the fair values of the derivative instruments are reported in OCI to the extent the hedge is effective. The gains and losses on derivative instruments that are reported in OCI are reflected in the consolidated statements of income in the periods in which the results of operations are impacted by the variability of the cash flows of the hedged item. Generally, net interest income is increased or decreased by amounts receivable or payable with respect to the derivatives, which qualify for hedge accounting. At inception of the hedge, the Corporation establishes the method it uses for assessing the effectiveness of the hedging derivative and the measurement approach for determining the ineffective aspect of the hedge. The ineffective portion of the hedge, if any, is recognized currently in the consolidated statements of operations. The Corporation excludes the time value expiration of the hedge when measuring ineffectiveness.
	The Corporation offers interest rate derivative products (e.g. interest rate swaps) to certain of its high-quality commercial borrowers. This product allows customers to enter into an agreement with the Corporation to swap their variable rate loan to a fixed rate. These derivative products are designed to reduce, eliminate or modify the risk of changes in the borrower’s interest rate or market price risk. The extension of credit incurred through the execution of these derivative products is subject to the same approvals and rigorous underwriting standards as the related traditional credit product. The Corporation limits its risk exposure to these products by entering into a mirror-image, offsetting swap agreement with a separate, well-capitalized and rated counterparty previously approved by the Credit and Asset Liability Committee. By using these interest rate swap arrangements, the Corporation is also better insulated from the interest rate risk associated with underwriting fixed-rate loans. These derivative contracts are not designated against specific assets or liabilities under ASC 815, Derivatives and Hedging, and, therefore, do not qualify for hedge accounting. The derivatives are recorded on the balance sheet at fair value and changes in fair value of both the customer and the offsetting swap agreements are recorded (and essentially offset) in non-interest income. The fair value of the derivative instruments incorporates a consideration of credit risk (in accordance with ASC 820), resulting in some volatility in earnings each period.
	INCOME TAX in the consolidated statements of income includes deferred income tax provisions or benefits for all significant temporary differences in recognizing income and expenses for financial reporting and income tax purposes. The Corporation files consolidated income tax returns with its subsidiaries.
	The Corporation adopted the provisions of the ASC 740, Income Taxes, which prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. ASC 740 also provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure and transition. As a result of the implementation of ASC 740, the Corporation did not identify any uncertain tax positions that it believes should be recognized in the financial statements. The tax years still subject to examination by taxing authorities are years subsequent to 2010.
	STOCK OPTION AND RESTRICTED STOCK AWARD PLANS are maintained by the Corporation. The compensation costs are recognized for stock options and restricted stock awards issued to employees and directors based on the fair value of these awards at the date of grant. A Black-Scholes model is utilized to estimate the fair value of stock options.  The market price of the Corporation’s common stock at the date of grant is used for restricted stock awards. Compensation expense is recognized over the appropriate service period, which is generally two or three years.
	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 Corporation 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 Corporation 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.
	NET INCOME PER SHARE is computed by dividing net income available to common shareholders by the weighted-average number of shares of common stock outstanding. Diluted net income per share is computed by dividing net income available to common shareholders by the weighted-average number of shares of common stock outstanding, plus the dilutive effect of outstanding stock options and nonvested restricted stock.
	RECLASSIFICATIONS have been made to prior financial statements to conform to the current financial statement presentation. These reclassifications had no effect on net income.

Purchase_and_Assumption

Purchase and Assumption	12 Months Ended
	Dec. 31, 2014
Business Acquisition [Line Items]
Purchase and Assumption	BUSINESS COMBINATIONS
	Community Bancshares, Inc.
	On November 7, 2014, the Corporation acquired 100 percent of Community Bancshares, Inc. ("Community"). Community was headquartered in Noblesville, Indiana and had 10 full-service banking centers serving central Indiana. Pursuant to the merger agreement, each outstanding share of common stock of Community was converted into the right to receive either (a) 4.0926 shares of the Corporation's common stock, plus cash in lieu of fractional shares; or (b) $85.94 in cash, based upon shareholder elections. The Corporation paid $14.2 million in cash and issued approximately 1.6 million shares of common stock, valued at approximately $35.0 million, for a total purchase price of approximately $49.2 million.
	The Corporation engaged in this transaction with the expectation that it would be accretive and expand the existing footprint in central Indiana. Goodwill resulted from this transaction due to the expected synergies from combining operations.
	Under the acquisition method of accounting, the total purchase price is allocated to net tangible and intangible assets based on their current estimated fair values on the date of the acquisition. Based on preliminary valuations of the fair value of tangible and intangible assets acquired and liabilities assumed, which are based on assumptions that are subject to change, the purchase price for the Community acquisition is detailed in the following table.
	Prior to the end of the one year measurement period for finalizing the purchase price allocation, if information becomes available which would indicate adjustments are required to the purchase price allocation, such adjustments will be included in the purchase price allocation retrospectively.
		Fair Value
	Cash and cash equivalents	$	4,124
	Interest -bearing time deposits	16,526
	Investment Securities, available for sale	76,807
	Loans	145,064
	Premises and equipment	3,610
	Federal Home Loan Bank stock	1,950
	Interest Receivable	767
	Cash surrender value of life insurance	3,266
	Other real estate owned	6,662
	Taxes, deferred and receivable	3,348
	Other assets	167
	Deposits	(228,424		)
	Interest payable	(98		)
	Other liabilities	(3,014		)
	Net tangible assets acquired	$	30,755
	Core deposit intangible	4,658
	Goodwill	13,776
	Purchase price	$	49,189
	Of the total purchase price, $4,658,000 has been allocated to a core deposit intangible that will be amortized over its estimated life of 10 years. The remaining purchase price has been allocated to goodwill, which is not deductible for tax purposes.
	CFS Bancorp, Inc.
	On November 12, 2013, the Corporation acquired 100 percent of CFS Bancorp, Inc. ("CFS") in an all stock transaction. CFS was headquartered in Munster, Indiana and had 20 full-service banking centers serving the northwestern Indiana and northeastern Illinois areas. Pursuant to the merger agreement, the shareholders of CFS received 0.65 percent of a share of the Corporation's common stock for each share of CFS Bancorp common stock held. The Corporation issued approximately 7.1 million shares of common stock, which was valued at approximately $135.6 million.
	The Corporation engaged in this transaction with the expectation that it would be accretive and add a new market area with a demographic profile consistent with many of the current Indiana markets served by the Bank. Goodwill resulted from this transaction due to the expected synergies from combining operations.
	The purchase price for the CFS acquisition was allocated as follows:
		Fair Value
	Cash and cash equivalents	$	10,992
	Interest-bearing time deposits	213,379
	Investment securities available for sale	15,913
	Investment securities held to maturity	14,372
	Mortgage loans held for sale	189
	Loans	603,114
	Premises and equipment	19,643
	Federal Home Loan Bank stock	6,188
	Interest receivable	1,770
	Cash surrender value of life insurance	36,555
	Other real estate owned	12,857
	Tax asset, deferred and receivable	30,717
	Other assets	111,656
	Deposits	(955,432		)
	Securities sold under repurchase agreements	(9,830		)
	Federal Home Loan Bank advances	(15,000		)
	Interest payable	(294		)
	Other liabilities	(16,033		)
	Net tangible assets acquired	$	80,756
	Core deposit intangible	7,313
	Goodwill	47,573
	Purchase price	$	135,642
	Of the total purchase price, $7,313,000 has been allocated to a core deposit intangible that will be amortized over its estimated life of 10 years. The remaining purchase price has been allocated to goodwill, which is not deductible for tax purposes.
	Pro Forma Financial Information
	The results of operations of Community and CFS have been included in the Corporation's consolidated financial statements since the acquisition dates. The following schedule includes pro forma results for the periods ended December 31, 2014, 2013 and 2012 as if the Community and CFS acquisitions had occurred as of the beginning of the comparable prior annual reporting period.
		2014			2013			2012
	Total revenue (net interest income plus other income)	$	263,070		$	253,668		$	266,034
	Net income	$	61,572		$	39,979		$	50,092
	Net income available to common shareholders	$	61,572		$	37,599		$	45,553
	Earnings per share:
	Basic	$	1.63		$	0.98		$	1.28
	Diluted	$	1.61		$	0.97		$	1.27
	The pro forma information includes adjustments for interest income on loans, amortization of intangibles arising from the transaction, interest expense on deposits acquired, premises expense for the banking centers acquired and the related income tax effects. The pro forma information for the year ended 2014 includes $1.6 million of operating revenue from Community since the acquisition and approximately $1.8 million, net of tax, of non-recurring expenses directly attributable to the Community acquisition. The pro forma information for the year ended 2013 includes $4.9 million of operating revenue from CFS since the acquisition and approximately $9.5 million, net of tax, of non-recurring expenses directly attributable to the CFS acquisition.
The pro forma financial information is presented for information purposes only and is not indicative of the results of operations that actually would have been achieved had the acquisition consummated as of that time, nor is it intended to be a projection of future results.
SCB Bank
Business Acquisition [Line Items]
Purchase and Assumption	PURCHASE AND ASSUMPTION
	Effective February 10, 2012, the Bank assumed substantially all of the deposits and certain other liabilities and acquired certain assets of SCB Bank, a federal savings bank headquartered in Shelbyville, Indiana, from the Federal Deposit Insurance Corporation (“FDIC”), as receiver for SCB Bank (the “Acquisition”), pursuant to the terms of the Purchase and Assumption Agreement - Modified Whole Bank; All Deposits (the “Agreement”), entered into by the Bank, the FDIC as receiver of SCB Bank and the FDIC.
	Under the terms of the Agreement, the Bank acquired $147.7 million in assets, including approximately $11.9 million of cash and cash equivalents, $18.9 million of marketable securities, $1.8 million in Federal Home Loan Bank stock, $113.0 million in loans and $2.1 million of premises and other assets. The Bank assumed approximately $135.7 million of liabilities, including approximately $125.9 million in customer deposits, $9.6 million of other borrowed money and $402,000 in other liabilities. These balances are book balances and do not reflect the fair value adjustments which are shown in the following table. The acquisition did not include any loss sharing agreement with the FDIC.
	The bid accepted by the FDIC included no deposit premium. The assets were acquired at a discount of $29.0 million from book value. The FDIC made a payment of $17.2 million to the Bank upon the final closing date balance sheet for SCB Bank that reflected the difference between the purchase price of the assets acquired and the value of the liabilities assumed.
	The Bank engaged in this transaction with the expectation that it would be immediately accretive and add a new market area with a demographic profile consistent with many of the current Indiana markets served by the Bank.
	The transaction was accounted for under the acquisition method of accounting in accordance with the Business Combination topic of the FASB Accounting Standards Codification (“ASC 310-20 and 310-30”). The statement of net assets and liabilities acquired as of February 10, 2012, are presented below. The assets and liabilities of SCB Bank were recorded at the respective acquisition date provisional fair values, and identifiable intangible assets were recorded at provisional fair value.
	Assets				Liabilities
	Cash and due from banks (1)	$	29,113		Deposits:
	Investment securities, available for sale	18,896			Non-interest bearing	$	13,715
	Federal Home Loan Bank stock	1,761			NOW accounts	14,746
	Loans:				Savings and money market	25,843
	Commercial	51,042			Certificate of deposit	71,605
	Residential mortgage	11,181			Total Deposits	125,909
	Installment	31,570
	Total Loans	93,793			Federal Home Loan Bank advances	10,286
					Other liabilities	804
	Premises	1,516			Total Liabilities Assumed	$	136,999
	Core deposit intangible	484
	Other assets	560			Net Gain on Acquisition	$	9,124
	Total Assets Purchased	$	146,123
	-1	Includes $17,200,000 cash received from the FDIC.
	In many cases, the fair values of assets acquired and liabilities assumed were determined by estimating cash flows expected to result from those assets and liabilities and discounting them at appropriate market rates. The most significant category of assets for which this procedure was used was acquired loans. The Bank acquired the $113.0 million loan portfolio at a fair value discount of $19.2 million. The performing portion of the portfolio,$86.3 million, had an estimated fair value of $76.5 million. The excess of expected cash flows above the fair value of the performing portion of loans will be accreted to interest income over the remaining lives of the loans in accordance with ASC 310-20. Discounts or premiums on term loans are accounted for under an effective yield method. Prepayments on term loans would be accounted for in the effective yield calculation. Discounts or premiums on lines of credit are treated in a straight line method over the term of the lines of credit.
	Certain loans for which specific credit-related deterioration has occurred since origination are recorded at fair value which is derived from calculating the present value of the amounts expected to be collected. Income recognition on these loans is based on reasonable expectation about the timing and amount of cash flows to be collected. Some of the acquired loans deemed impaired and considered collateral dependent, with the timing of a sale of loan collateral indeterminate, remain on non-accrual status and have little or no accretable yield.
	In accordance with ASC 310-30 (formerly Statement of Position (“SOP”) 03-3 as of February 10, 2012, loans acquired during 2012 for which it was probable at acquisition that all contractually required payments would not be collected are as follows:
	Preliminary estimate of contractually required principal and interest at acquisition	$	31,143
	Preliminary estimate of contractual cash flows not expected to be collected (nonaccretable differences)	9,688
	Preliminary estimate of expected cash flows at acquisition	21,455
	Preliminary estimate of interest component of expected cash flows (accretable discount)	4,152
	Preliminary estimate of fair value of acquired loans accounted for under ASC 310-30	$	17,303
	Pro-forma statements were determined to be impracticable due to the nature of the transaction as certain assets were not purchased.

Business_Combination

Business Combination	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Business Combinations	BUSINESS COMBINATIONS
	Community Bancshares, Inc.
	On November 7, 2014, the Corporation acquired 100 percent of Community Bancshares, Inc. ("Community"). Community was headquartered in Noblesville, Indiana and had 10 full-service banking centers serving central Indiana. Pursuant to the merger agreement, each outstanding share of common stock of Community was converted into the right to receive either (a) 4.0926 shares of the Corporation's common stock, plus cash in lieu of fractional shares; or (b) $85.94 in cash, based upon shareholder elections. The Corporation paid $14.2 million in cash and issued approximately 1.6 million shares of common stock, valued at approximately $35.0 million, for a total purchase price of approximately $49.2 million.
	The Corporation engaged in this transaction with the expectation that it would be accretive and expand the existing footprint in central Indiana. Goodwill resulted from this transaction due to the expected synergies from combining operations.
	Under the acquisition method of accounting, the total purchase price is allocated to net tangible and intangible assets based on their current estimated fair values on the date of the acquisition. Based on preliminary valuations of the fair value of tangible and intangible assets acquired and liabilities assumed, which are based on assumptions that are subject to change, the purchase price for the Community acquisition is detailed in the following table.
	Prior to the end of the one year measurement period for finalizing the purchase price allocation, if information becomes available which would indicate adjustments are required to the purchase price allocation, such adjustments will be included in the purchase price allocation retrospectively.
		Fair Value
	Cash and cash equivalents	$	4,124
	Interest -bearing time deposits	16,526
	Investment Securities, available for sale	76,807
	Loans	145,064
	Premises and equipment	3,610
	Federal Home Loan Bank stock	1,950
	Interest Receivable	767
	Cash surrender value of life insurance	3,266
	Other real estate owned	6,662
	Taxes, deferred and receivable	3,348
	Other assets	167
	Deposits	(228,424		)
	Interest payable	(98		)
	Other liabilities	(3,014		)
	Net tangible assets acquired	$	30,755
	Core deposit intangible	4,658
	Goodwill	13,776
	Purchase price	$	49,189
	Of the total purchase price, $4,658,000 has been allocated to a core deposit intangible that will be amortized over its estimated life of 10 years. The remaining purchase price has been allocated to goodwill, which is not deductible for tax purposes.
	CFS Bancorp, Inc.
	On November 12, 2013, the Corporation acquired 100 percent of CFS Bancorp, Inc. ("CFS") in an all stock transaction. CFS was headquartered in Munster, Indiana and had 20 full-service banking centers serving the northwestern Indiana and northeastern Illinois areas. Pursuant to the merger agreement, the shareholders of CFS received 0.65 percent of a share of the Corporation's common stock for each share of CFS Bancorp common stock held. The Corporation issued approximately 7.1 million shares of common stock, which was valued at approximately $135.6 million.
	The Corporation engaged in this transaction with the expectation that it would be accretive and add a new market area with a demographic profile consistent with many of the current Indiana markets served by the Bank. Goodwill resulted from this transaction due to the expected synergies from combining operations.
	The purchase price for the CFS acquisition was allocated as follows:
		Fair Value
	Cash and cash equivalents	$	10,992
	Interest-bearing time deposits	213,379
	Investment securities available for sale	15,913
	Investment securities held to maturity	14,372
	Mortgage loans held for sale	189
	Loans	603,114
	Premises and equipment	19,643
	Federal Home Loan Bank stock	6,188
	Interest receivable	1,770
	Cash surrender value of life insurance	36,555
	Other real estate owned	12,857
	Tax asset, deferred and receivable	30,717
	Other assets	111,656
	Deposits	(955,432		)
	Securities sold under repurchase agreements	(9,830		)
	Federal Home Loan Bank advances	(15,000		)
	Interest payable	(294		)
	Other liabilities	(16,033		)
	Net tangible assets acquired	$	80,756
	Core deposit intangible	7,313
	Goodwill	47,573
	Purchase price	$	135,642
	Of the total purchase price, $7,313,000 has been allocated to a core deposit intangible that will be amortized over its estimated life of 10 years. The remaining purchase price has been allocated to goodwill, which is not deductible for tax purposes.
	Pro Forma Financial Information
	The results of operations of Community and CFS have been included in the Corporation's consolidated financial statements since the acquisition dates. The following schedule includes pro forma results for the periods ended December 31, 2014, 2013 and 2012 as if the Community and CFS acquisitions had occurred as of the beginning of the comparable prior annual reporting period.
		2014			2013		2012
	Total revenue (net interest income plus other income)	$	263,070		$	253,668	$	266,034
	Net income	$	61,572		$	39,979	$	50,092
	Net income available to common shareholders	$	61,572		$	37,599	$	45,553
	Earnings per share:
	Basic	$	1.63		$	0.98	$	1.28
	Diluted	$	1.61		$	0.97	$	1.27
	The pro forma information includes adjustments for interest income on loans, amortization of intangibles arising from the transaction, interest expense on deposits acquired, premises expense for the banking centers acquired and the related income tax effects. The pro forma information for the year ended 2014 includes $1.6 million of operating revenue from Community since the acquisition and approximately $1.8 million, net of tax, of non-recurring expenses directly attributable to the Community acquisition. The pro forma information for the year ended 2013 includes $4.9 million of operating revenue from CFS since the acquisition and approximately $9.5 million, net of tax, of non-recurring expenses directly attributable to the CFS acquisition.
The pro forma financial information is presented for information purposes only and is not indicative of the results of operations that actually would have been achieved had the acquisition consummated as of that time, nor is it intended to be a projection of future results.

Restriction_on_Cash_and_Due_Fr

Restriction on Cash and Due From Banks	12 Months Ended
	Dec. 31, 2014
Cash and Cash Equivalents [Abstract]
Restriction on Cash and Due From Banks	RESTRICTION ON CASH AND DUE FROM BANKS
	The Corporation considers all liquid investments with original maturities of three months or less to be cash equivalents. As of December 31, 2014, cash and cash equivalents is defined to include cash on hand, deposits in other institutions and federal funds sold.
	Effective October 3, 2008, the FDIC’s insurance limits temporarily increased to $250,000. On July 21, 2010, the Dodd-Frank Wall Street Reform and Consumer Protection Act (“Dodd-Frank Act”) was signed into law, which, in part, permanently raised the standard maximum deposit insurance amount to $250,000.  On November 9, 2010, the FDIC implemented section 343 of the Dodd-Frank Act providing unlimited insurance coverage on noninterest-bearing transaction accounts.  Beginning December 31, 2010, through December 31, 2012, all noninterest-bearing transaction accounts were fully insured, regardless of the balance of the account, at all FDIC-insured institutions.  As of January 1, 2013, noninterest-bearing transaction deposit accounts are no longer insured separately from other accounts at the same FDIC-insured institution. Instead, noninterest-bearing transaction accounts are added to any of the Corporation's other accounts, and the aggregate balance insured up to at least the Standard Maximum Deposit Insurance Amount of $250,000, at each institution.
	At December 31, 2014, the Corporation’s interest-bearing cash accounts and noninterest-bearing transaction deposits held at other institutions exceeded federally insured limits by approximately $103,154,000. Each correspondent bank’s financial performance and market rating are reviewed on a quarterly basis to ensure the Corporation has deposits only at institutions providing minimal risk for those exceeding the federally insured limits.
	Additionally, the Corporation had approximately $13,910,000 at the Federal Home Loan Bank and Federal Reserve Bank, which are government-sponsored entities not insured by the FDIC.
	The Corporation is required to maintain reserve funds in cash and/or on deposit with the Federal Reserve Bank.  The reserve required at December 31, 2014, was $22,595,000.

Investment_Securities

Investment Securities	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Investment Securities	INVESTMENT SECURITIES
	The amortized cost, gross unrealized gains, gross unrealized losses and approximate market value of the Corporation's investment securities at the dates indicated were:
		Amortized Cost			Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	Available for sale at December 31, 2014
	U.S. Government-sponsored agency securities	$	100		$	9			$	109
	State and municipal	216,915			11,801		$	123	228,593
	U.S. Government-sponsored mortgage-backed securities	310,460			8,771		127		319,104
	Corporate obligations	31							31
	Equity securities	1,706							1,706
	Total available for sale	529,212			20,581		250		549,543
	Held to maturity at December 31, 2014
	State and municipal	204,443			5,716		96		210,063
	U.S. Government-sponsored mortgage-backed securities	426,645			11,527		512		437,660
	Total held to maturity	631,088			17,243		608		647,723
	Total Investment Securities	$	1,160,300		$	37,824	$	858	$	1,197,266
	Available for sale at December 31, 2013
	U.S. Treasury	$	15,914		$	80	$	21	$	15,973
	U.S. Government-sponsored agency securities	3,550			12		17		3,545
	State and municipal	231,005			3,878		3,896		230,987
	U.S. Government-sponsored mortgage-backed securities	279,299			3,926		1,973		281,252
	Corporate obligations	6,374					3,636		2,738
	Equity securities	1,706							1,706
	Total available for sale	537,848			7,896		9,543		536,201
	Held to maturity at December 31, 2013
	State and municipal	145,941			62		91		145,912
	U.S. Government-sponsored mortgage-backed securities	413,437			5,220		3,722		414,935
	Total held to maturity	559,378			5,282		3,813		560,847
	Total Investment Securities	$	1,097,226		$	13,178	$	13,356	$	1,097,048
	Certain investments in debt securities are reported in the financial statements at amounts less than their historical cost.  The historical cost of these investments totaled $73,249,000 and $490,488,000 at December 31, 2014 and 2013, respectively.  Total fair value of these investments was $72,390,000  and $477,132,000, which was approximately 6.1 and 43.6 percent of the Corporation's available for sale and held to maturity investment portfolio at December 31, 2014 and 2013, respectively.
	Except as discussed below, management believes the decline in fair value for these securities was temporary. Should the impairment of any of these securities become other-than-temporary, the cost basis of the investment will be reduced and the resulting loss recognized in net income during the period the other-than-temporary impairment (“OTTI”) is identified.
	The Corporation’s management has evaluated all securities with unrealized losses for OTTI as of December 31, 2014.  The evaluations are based on the nature of the securities, the extent and duration of the loss and the intent and ability of the Corporation to hold these securities either to maturity or through the expected recovery period.
	In determining the fair value of the investment securities portfolio, the Corporation utilizes a third party for portfolio accounting services, including market value input, for those securities classified as Level I and Level II in the fair value hierarchy.  The Corporation has obtained an understanding of what inputs are being used by the vendor in pricing the portfolio and how the vendor classified these securities based upon these inputs.  From these discussions, the Corporation’s management is comfortable that the classifications are proper.  The Corporation has gained trust in the data for two reasons:  (a) independent spot testing of the data is conducted by the Corporation through obtaining market quotes from various brokers on a periodic basis; and (b) actual gains or loss resulting from the sale of certain securities has proven the data to be accurate over time.   Fair value of securities classified as Level 3 in the valuation hierarchy was determined using a discounted cash flow model that incorporated market estimates of interest rates and volatility in markets that have not been active.
	U.S. Government-Sponsored Mortgage-Backed Securities
	The unrealized losses on the Corporation's investment in mortgage-backed securities were a result of interest rate changes. The Corporation expects to recover the amortized cost basis over the term of the securities. Because the decline in market value is attributable to changes in interest rates and not credit quality, and because the Corporation does not intend to sell the investments and it is not more likely than not that the Corporation will be required to sell the investments before recovery of their amortized cost basis, which may be maturity, the Corporation does not consider those investments to be other-than-temporarily impaired at December 31, 2014. As noted in the table above, the mortgage-backed securities portfolio contains unrealized losses of $127,000 on four securities and $512,000 on thirteen securities in the available for sale and held to maturity portfolios, respectively. All these securities are issued by a government-sponsored entity.
	State and Municipal Securities
	The unrealized losses on the Corporation's investments in securities of state and political subdivisions were caused by interest rate increases. The contractual terms of those investments do not permit the issuer to settle the securities at a price less than the amortized cost basis of the investments. Because the Corporation does not intend to sell the investments and it is not more likely than not that the Corporation will be required to sell the investments before recovery of their amortized cost basis, which may be maturity, the Corporation does not consider those investments to be other-than-temporarily impaired at December 31, 2014. As noted in the table above, the state and political subdivision securities portfolio contains unrealized losses of $123,000 on twenty-two securities and $96,000 on sixteen securities in the available for sale and held to maturity portfolios respectively.
	Corporate Obligations
	In 2013, the Corporation’s unrealized losses on trust preferred securities totaled $3.6 million on a book value of $6.4 million. In 2014, the Corporation sold all but one of its trust preferred securities, which resulted in gains of $1.9 million. These securities had previous OTTI of $9.4 million. The one remaining trust preferred security has no remaining book value as a result of OTTI of approximately $500,000 taken in 2009.
	Certain Losses Recognized on Investments
	Certain debt securities have experienced fair value deterioration due to credit losses and other market factors.  The following table provides information about debt securities for which only a credit loss was recognized in income and other losses were recorded in other comprehensive income.
		Accumulated Credit Losses in			Accumulated Credit Losses in
		2014			2013
	Credit losses on debt securities held:
	Balance, January 1	$	11,355		$	11,355
	Reductions for previous other-than-temporary losses realized on securities sold during the year	(10,855		)
	Balance, December 31	$	500		$	11,355
	The following table shows the Corporation’s gross unrealized losses and fair value, aggregated by investment category and length of time the individual securities have been in a continuous unrealized loss position at December 31, 2014 and 2013:
		Less than					12 Months				Total
		12 Months					or Longer
		Fair			Gross		Fair		Gross		Fair		Gross
		Value			Unrealized		Value		Unrealized		Value		Unrealized
					Losses				Losses				Losses
	Temporarily Impaired Available for Sale Securities at December 31, 2014
	State and municipal	$	1,256		$	7	$	9,850	$	116	$	11,106	$	123
	U.S. Government-sponsored mortgage-backed securities	2,186			13		5,447		114		7,633		127
	Total Temporarily Impaired Available for Sale Securities	3,442			20		15,297		230		18,739		250
	Temporarily Impaired Held to Maturity Securities at December 31, 2014
	State and municipal	5,119			96		250				5,369		96
	U.S. Government-sponsored mortgage-backed securities	9,791			82		38,491		430		48,282		512
	Total Temporarily Impaired Held to Maturity Securities	14,910			178		38,741		430		53,651		608
	Total Temporarily Impaired Investment Securities	$	18,352		$	198	$	54,038	$	660	$	72,390	$	858
		Less than					12 Months				Total
		12 Months					or Longer
		Fair			Gross		Fair		Gross		Fair		Gross
Value			Unrealized		Value		Unrealized		Value		Unrealized
			Losses				Losses				Losses
Temporarily Impaired Available for Sale Securities at December 31, 2013
U.S. Treasury	$	4,875		$	21					$	4,875	$	21
U.S. Government-sponsored agency securities	3,433			17						3,433		17
State and municipal	111,791			3,840		$	583	$	56	112,374		3,896
U.S. Government-sponsored mortgage-backed securities	117,866			1,701		2,683		272		120,549		1,973
Corporate obligations						2,711		3,636		2,711		3,636
Total Temporarily Impaired Available for Sale Securities	237,965			5,579		5,977		3,964		243,942		9,543
Temporarily Impaired Held to Maturity Securities at December 31, 2013
State and municipal	17,318			91		184				17,502		91
U.S. Government-sponsored mortgage-backed securities	213,048			3,462		2,640		260		215,688		3,722
Total Temporarily Impaired Held to Maturity Securities	230,366			3,553		2,824		260		233,190		3,813
Total Temporarily Impaired Investment Securities	$	468,331		$	9,132	$	8,801	$	4,224	$	477,132	$	13,356
The amortized cost and fair value of securities available for sale and held to maturity at December 31, 2014 by contractual maturity are shown below.  Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties.
	Available for Sale					Held to Maturity
	Amortized Cost			Fair Value		Amortized Cost		Fair Value
Maturity Distribution at December 31, 2014
Due in one year or less	$	3,127		$	3,153	$	6,258	$	6,329
Due after one through five years	9,565			9,840		18,440		18,930
Due after five through ten years	48,675			50,889		85,997		87,903
Due after ten years	155,679			164,851		93,748		96,901
	217,046			228,733		204,443		210,063
U.S. Government-sponsored mortgage-backed securities	310,460			319,104		426,645		437,660
Equity securities	1,706			1,706
Total Investment Securities	$	529,212		$	549,543	$	631,088	$	647,723
Securities with a carrying value of approximately $449,408,000, $373,533,000 and $345,866,000  were pledged at December 31, 2014, 2013 and 2012, respectively, to secure certain deposits and securities sold under repurchase agreements, and for other purposes as permitted or required by law.
Gross gains of $3,581,000, $487,000 and $2,389,000 were realized on sales of available for sale securities in 2014, 2013 and 2012, respectively. There were no losses from the sale of available for sale securities in 2014, 2013 or 2012, respectively.

Loans_and_Allowance

Loans and Allowance	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Loans and Allowance	LOANS AND ALLOWANCE
	The Corporation's primary lending focus is small business and middle market commercial, commercial real estate, residential real estate and consumer, which results in portfolio diversification. The following tables show the composition of the loan portfolio, the allowance for loan losses and certain credit quality elements, all excluding loans held for sale.  Loans held for sale at December 31, 2014 and 2013, were $7,235,000 and $5,331,000, respectively.
	The following table illustrates the composition of the Corporation’s loan portfolio by loan class for the years indicated:
		31-Dec-14				31-Dec-13
	Commercial and industrial loans	$	896,688			$	761,705
	Agricultural production financing and other loans to farmers	104,927				114,348
	Real estate loans:
	Construction	207,221				177,082
	Commercial and farmland	1,672,661				1,611,809
	Residential	647,315				616,385
	Home equity	286,529				255,223
	Individuals' loans for household and other personal expenditures	73,400				69,783
	Lease financing receivables, net of unearned income	1,106				1,545
	Other loans	35,018				24,529
	Loans	3,924,865				3,632,409
	Allowance for loan losses	(63,964		)		(67,870		)
	Net Loans	$	3,860,901			$	3,564,539
	Allowance, Credit Quality and Loan Portfolio
	The Corporation maintains an allowance for loan losses to cover probable credit losses identified during its loan review process. Management believes that the allowance for loan losses is adequate to cover probable losses inherent in the loan portfolio at December 31, 2014.  The process for determining the adequacy of the allowance for loan losses is critical to the Corporation’s financial results.  It requires management to make difficult, subjective and complex judgments to estimate the effect of uncertain matters.  The allowance for loan losses considers current factors, including economic conditions and ongoing internal and external examinations, and will increase or decrease as deemed necessary to ensure the allowance remains adequate.  In addition, the allowance as a percentage of charge offs and nonperforming loans will change at different points in time based on credit performance, loan mix and collateral values.
	The allowance is increased by the provision for loan losses and decreased by charge offs less recoveries. All charge offs are approved by the Bank’s senior loan officers or loan committees, depending on the amount of the charge off. The Bank charges off a loan when a determination is made that all or a portion of the loan is uncollectible. The allowance for loan losses is maintained through the provision for loan losses, which is a charge against earnings. The amount provided for loan losses in a given period may be greater than or less than net loan losses experienced during the period, and is based on management’s judgment as to the appropriate level of the allowance for loan losses. The determination of the provision amount in a given period is based on management’s ongoing review and evaluation of the loan portfolio, including an internally administered loan "watch" list and independent loan reviews.  The evaluation takes into consideration identified credit problems, the possibility of losses inherent in the loan portfolio that are not specifically identified and management’s judgment as to the impact of the current environment and economic conditions on the portfolio.
	In conformance with ASC 805 and ASC 820, loans purchased after December 31, 2008 are recorded at the acquisition date fair value. Such loans are only included in the allowance to the extent a specific impairment is identified that exceeds the fair value adjustment on an impaired loan or the historical loss and environmental factor analysis indicates losses inherent in a purchased portfolio exceeds the fair value adjustment on the portion of the purchased portfolio not deemed impaired.
	The allowance consists of specific impairment reserves as required by ASC 310-10-35, a component for historical losses in accordance with ASC 450 and the consideration of current environmental factors in accordance with ASC 450. A loan is deemed impaired when, based on current information or events, it is probable that all amounts due of principal and interest according to the contractual terms of the loan agreement will not be collected.
	The historical loss allocation for loans not deemed impaired according to ASC 310 is the product of the volume of loans within the non-impaired criticized and non-criticized risk grade classifications, each segmented by call code, and the historical loss factor for each respective classification and call code segment. The historical loss factors are based upon actual loss experience within each risk and call code classification. The historical look back period for non-criticized loans looks to the most recent rolling-four-quarter average and aligns with the look back period for non-impaired criticized loans. Each of the rolling four quarter periods used to obtain the average, include all charge offs for the previous twelve-month period, therefore the historical look back period includes seven quarters. The resulting allocation is reflective of current conditions. Criticized loans are grouped based on the risk grade assigned to the loan. Loans with a special mention grade are assigned a loss factor, and loans with a classified grade but not impaired are assigned a separate loss factor. The loss factor computation for this allocation includes a segmented historical loss migration analysis of criticized risk grades to charge off.
	In addition to the specific reserves and historical loss components of the allowance, consideration is given to various environmental factors to help ensure that losses inherent in the portfolio are reflected in the allowance for loan losses. The environmental component adjusts the historical loss allocations for commercial and consumer loans to reflect relevant current conditions that, in management's opinion, have an impact on loss recognition. Environmental factors that management reviews in the analysis include: national and local economic trends and conditions; trends in growth in the loan portfolio and growth in higher risk areas; levels of, and trends in, delinquencies and non-accruals; experience and depth of lending management and staff; adequacy of, and adherence to, lending policies and procedures including those for underwriting; industry concentrations of credit; and adequacy of risk identification systems and controls through the internal loan review and internal audit processes.
	At December 31, 2014, the allowance for loan losses was $63,964,000, a decrease of $3,906,000 from the December 31, 2013 balance of $67,870,000. Specific reserves on impaired loans increased $1,186,000 to $2,769,000, from $1,583,000 at December 31, 2013. Net charge offs for the twelve months ended December 31, 2014, were $6,466,000, a decrease of $1,678,000 from the same period in 2013. The provision for loan losses for the twelve months ended December 31, 2014 was $2,560,000, a decrease of $4,088,000 for the same period in in 2013. The determination of the provision for loan losses in any period is based on management’s continuing review and evaluation of the loan portfolio, and its judgment as to the impact of current economic conditions on the portfolio.
	The following table summarizes changes in the allowance for loan losses by loan segment for the twelve months ended December 31, 2014, 2013 and 2012:
		Twelve Months Ended December 31, 2014
		Commercial				Commercial Real Estate			Consumer			Residential			Finance				Total
															Leases
	Allowance for loan losses:
	Balances, January 1	$	27,176			$	23,102		$	2,515		$	15,077						$	67,870
	Provision for losses	3,459				(464		)	423			(839		)	$	(19	)		2,560
	Recoveries on loans	5,435				3,297			377			1,783			24				10,916
	Loans charged off	(7,246		)		(6,608		)	(657		)	(2,869		)	(2		)		(17,382		)
	Balances, December 31, 2014	$	28,824			$	19,327		$	2,658		$	13,152		$	3			$	63,964
		Twelve Months Ended December 31, 2013
		Commercial				Commercial Real Estate			Consumer			Residential			Finance				Total
															Leases
	Allowance for loan losses:
	Balances, January 1	$	25,913			$	26,703		$	2,593		$	14,157						$	69,366
	Provision for losses	2,794				340			(11		)	3,514			$	11			6,648
	Recoveries on loans	4,586				3,552			556			1,292			4				9,990
	Loans charged off	(6,117		)		(7,493		)	(623		)	(3,886		)	(15		)		(18,134		)
	Balances, December 31, 2013	$	27,176			$	23,102		$	2,515		$	15,077						$	67,870
		Twelve Months Ended December 31, 2012
		Commercial				Commercial Real Estate			Consumer			Residential			Finance				Total
															Leases
	Allowance for loan losses:
	Balances, January 1	$	17,731			$	37,919		$	2,902		$	12,343		$	3			$	70,898
	Provision for losses	14,749				(2,546		)	126			6,176			29				18,534
	Recoveries on loans	1,744				3,652			695			1,113			2				7,206
	Loans charged off	(8,311		)		(12,322		)	(1,130		)	(5,475		)	(34		)		(27,272		)
	Balances, December 31, 2012	$	25,913			$	26,703		$	2,593		$	14,157						$	69,366
	The following tables show the Corporation’s allowance for loan losses and loan portfolio by loan segment for the years indicated:
		December 31, 2014
		Commercial				Commercial			Consumer			Residential			Finance				Total
						Real Estate									Leases
	Allowance balances:
	Individually evaluated for impairment	$	1,455			$	470					$	194						$	2,119
	Collectively evaluated for impairment	27,369				18,207			$	2,658		12,958			$	3			61,195
	Loans acquired with deteriorated credit quality					650													650
	Total Allowance for Loan Losses	$	28,824			$	19,327		$	2,658		$	13,152		$	3			$	63,964
	Loan balances:
	Individually evaluated for impairment	$	16,108			$	23,963					$	4,022						$	44,093
Collectively evaluated for impairment	1,011,122				1,796,797			$	73,400		925,282			$	1,106			3,807,707
Loans acquired with deteriorated credit quality	9,403				59,122						4,540							73,065
Loans	$	1,036,633			$	1,879,882		$	73,400		$	933,844		$	1,106			$	3,924,865
	December 31, 2013
	Commercial				Commercial			Consumer			Residential			Finance				Total
					Real Estate									Leases
Allowance balances:
Individually evaluated for impairment	$	585			$	763					$	6						$	1,354
Collectively evaluated for impairment	26,493				22,208			$	2,515		15,071							66,287
Loans acquired with deteriorated credit quality	98				131													229
Total Allowance for Loan Losses	$	27,176			$	23,102		$	2,515		$	15,077						$	67,870
Loan balances:
Individually evaluated for impairment	$	10,240			$	29,007					$	2,820						$	42,067
Collectively evaluated for impairment	882,794				1,690,285			$	69,783		867,094			$	1,545			3,511,501
Loans acquired with deteriorated credit quality	7,548				69,599						1,694							78,841
Loans	$	900,582			$	1,788,891		$	69,783		$	871,608		$	1,545			$	3,632,409
The risk characteristics of the Corporation’s material portfolio segments are as follows:
Commercial
Commercial loans are primarily based on the identified cash flows of the borrower and secondarily on the underlying collateral provided by the borrower. The cash flows of borrowers, however, may not be as expected and the collateral securing these loans may fluctuate in value. Most commercial loans are secured by the assets being financed or other business assets such as accounts receivable or inventory and may incorporate a personal guarantee; however, some short-term loans may be made on an unsecured basis. In the case of loans secured by accounts receivable, the availability of funds for the repayment of these loans may be substantially dependent on the ability of the borrower to collect amounts due from its customers.
Commercial real estate
These loans are viewed primarily as cash flow loans and secondarily as loans secured by real estate. Commercial real estate lending typically involves higher loan principal amounts and the repayment of these loans is generally dependent on the successful operation of the property securing the loan or the business conducted on the property securing the loan. Commercial real estate loans may be more adversely affected by conditions in the real estate markets or in the general economy. Management monitors and evaluates commercial real estate loans based on collateral and risk grade criteria. In addition, management tracks the level of owner-occupied commercial real estate loans versus non-owner occupied loans.
Residential and Consumer
With respect to residential loans that are secured by 1-4 family residences and are typically owner occupied, the Corporation generally establishes a maximum loan-to-value ratio and requires private mortgage insurance if that ratio is exceeded. Home equity loans are typically secured by a subordinate interest in 1-4 family residences, and consumer loans are secured by consumer assets such as automobiles or recreational vehicles. Some consumer loans are unsecured such as small installment loans and certain lines of credit. Repayment of these loans is primarily dependent on the personal income and credit rating of the borrowers, which can be impacted by economic conditions in their market areas such as unemployment levels. Repayment can also be impacted by changes in property values on residential properties. Risk is mitigated by the fact that the loans are of smaller individual amounts and spread over a large number of borrowers.
Loans are reclassified to a non-accruing status when, in management’s judgment, the collateral value and financial condition of the borrower do not justify accruing interest. Uncollected interest previously recorded, but not deemed collectible, is reversed and charged against current income. Payments subsequently received on non-accrual loans are applied to principal. A loan is returned to accrual status when principal and interest are no longer past due and collectability is probable, typically after a minimum of six consecutive months of performance.  Payments received on impaired accruing or delinquent loans are applied to interest income as accrued.
The following table summarizes the Corporation’s non-accrual loans by loan class for the years indicated:
	31-Dec-14				31-Dec-13
Commercial and industrial loans	$	7,048			$	9,283
Agriculture production financing and other loans to farmers	5,800				30
Real estate loans:
Construction	1,439				4,978
Commercial and farmland	19,350				28,095
Residential	12,933				12,068
Home equity	1,988				1,667
Individuals' loans for household and other personal expenditures	231				117
Other loans					164
Total	$	48,789			$	56,402
Commercial impaired loans include non-accrual loans, loans accounted for under ASC 310-30, as well as substandard, doubtful and loss grade loans that were still accruing but deemed impaired according to the guidance set forth in ASC 310. Also included in impaired loans are accruing loans that are contractually past due 90 days or more and troubled debt restructurings.
Allowable methods for determining the amount of impairment include estimating fair value using the fair value of the collateral for collateral dependent loans. If the impaired loan is identified as collateral dependent, then the fair value method of measuring the amount of impairment is utilized.  This method requires obtaining a current independent appraisal of the collateral and applying a discount factor to the value. The fair value of real estate is generally based on appraisals by qualified licensed appraisers. The appraisers typically determine the value of the real estate by utilizing an income or market valuation approach. If an appraisal is not available, the fair value may be determined by using a cash flow analysis. Fair value on other collateral such as business assets is typically ascertained by assessing, either singularly or some combination of, asset appraisals, accounts receivable aging reports, inventory listings and or customer financial statements. Both appraised values and values based on borrower’s financial information are discounted as considered appropriate based on age and quality of the information and current market conditions.
The following tables show the composition of the Corporation’s commercial impaired loans by loan class for the years indicated:
	December 31, 2014
	Unpaid Principal				Recorded			Related			Average Recorded Investment			Interest Income Recognized
	Balance				Investment			Allowance
Impaired loans with no related allowance:
Commercial and industrial loans	$	35,514			$	18,029					$	18,711		$	362
Agriculture production financing and other loans to farmers	26				22						26
Real estate loans:
Construction	12,956				9,318						9,837			427
Commercial and farmland	95,856				68,187						70,844			3,389
Residential	10,591				6,839						6,987			119
Home equity	3,590				398						402
Other loans	30
Total	$	158,563			$	102,793					$	106,807		$	4,297
Impaired loans with related allowance:
Commercial and industrial loans	$	1,766			$	1,684		$	1,055		$	1,721		$	40
Agriculture production financing and other loans to farmers	6,777				5,777			400			8,044			1
Real estate loans:
Commercial and farmland	7,159				4,971			1,120			4,999			24
Residential	1,001				998			194			1,000
Total	$	16,703			$	13,430		$	2,769		$	15,764		$	65
Total Impaired Loans	$	175,266			$	116,223		$	2,769		$	122,571		$	4,362
	December 31, 2013
	Unpaid Principal				Recorded			Related			Average Recorded Investment			Interest Income Recognized
	Balance				Investment			Allowance
Impaired loans with no related allowance:
Commercial and industrial loans	$	35,066			$	16,371					$	19,209		$	192
Agriculture production financing and other loans to farmers	32				30						32
Real estate loans:
Construction	16,109				10,625						11,621			117
Commercial and farmland	128,073				83,033						84,057			1,663
Residential	6,746				3,910						4,236			75
Home equity	3,299				112						225
Other loans	454				172						181			1
Total	$	189,779			$	114,253					$	119,561		$	2,048
Impaired loans with related allowance:
Commercial and industrial loans	$	1,390			$	1,216		$	683		$	1,240		$	9
Real estate loans:
Construction
Commercial and farmland	4,657				4,215			894			4,291			9
Residential	74				71			6			76
Total	$	6,121			$	5,502		$	1,583		$	5,607		$	18
Total Impaired Loans	$	195,900			$	119,755		$	1,583		$	125,168		$	2,066
	December 31, 2012
	Unpaid Principal				Recorded			Related			Average Recorded Investment			Interest Income Recognized
	Balance				Investment			Allowance
Impaired loans with no related allowance:
Commercial and industrial loans	$	28,532			$	11,730					$	15,089		$	124
Real estate loans:
Construction	9,787				5,164						6,471			66
Commercial and farmland	58,173				43,204						46,788			1,211
Residential	8,820				6,215						7,129			83
Home equity	4,199				1,006						1,022			13
Other loans	83				14						18			1
Total	$	109,594			$	67,333					$	76,517		$	1,498
Impaired loans with related allowance:
Commercial and industrial loans	$	4,415			$	4,155		$	1,628		$	4,225		$	33
Real estate loans:
Construction	1,202				1,058			105			1,175
Commercial and farmland	5,579				5,182			2,460			5,239			95
Residential	1,722				1,451			50			1,458			75
Total	$	12,918			$	11,846		$	4,243		$	12,097		$	203
Total Impaired Loans	$	122,512			$	79,179		$	4,243		$	88,614		$	1,701
At December 31, 2014, the commercial impaired loan total of $116,223,000 included $17,027,000 in loans acquired from Community. At December 31, 2013, the commercial impaired loan total of $119,755,000 included $69,448,000 in loans acquired from CFS. At December 31, 2012, the commercial impaired loan total of $79,179,000 included $17,334,000 in loans acquired from SCB.
As part of the ongoing monitoring of the credit quality of the Corporation's loan portfolio, management tracks certain credit quality indicators including trends related to: (i) the level of criticized commercial loans, (ii) net charge offs, (iii) non-performing loans and (iv) the general national and local economic conditions.
The Corporation utilizes a risk grading of pass, special mention, substandard, doubtful and loss to assess the overall credit quality of large commercial loans. All large commercial credit grades are reviewed at a minimum of once a year for pass grade loans. Loans with grades below pass are reviewed more frequently depending on the grade. A description of the general characteristics of these grades is as follows:
•	Pass - Loans that are considered to be of acceptable credit quality.
•	Special Mention - Loans which possess some credit deficiency or potential weakness, which deserves close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the asset or in the Corporation's credit position at some future date. Special mention assets are not adversely classified and do not expose the Corporation to sufficient risk to warrant adverse classification. The key distinctions of this category's classification are that it is indicative of an unwarranted level of risk; and weaknesses are considered “potential”, not “defined”, impairments to the primary source of repayment. Examples include businesses that may be suffering from inadequate management, loss of key personnel or significant customer or litigation.
•	Substandard - A substandard loan is inadequately protected by the current net worth and paying capacity of the obligor or of the collateral pledged, if any. Assets so classified have a well-defined weakness that jeopardizes the liquidation of the debt. They are characterized by the distinct possibility that the Corporation will sustain some loss if the deficiencies are not corrected. Other characteristics may include:
	o	the likelihood that a loan will be paid from the primary source of repayment is uncertain or financial deterioration is underway and very close attention is warranted to ensure that the loan is collected without loss,
	o	the primary source of repayment is gone, and the Corporation is forced to rely on a secondary source of repayment, such as collateral liquidation or guarantees,
	o	loans have a distinct possibility that the Corporation will sustain some loss if deficiencies are not corrected,
	o	unusual courses of action are needed to maintain a high probability of repayment,
	o	the borrower is not generating enough cash flow to repay loan principal; however, it continues to make interest payments,
	o	the Corporation is forced into a subordinated or unsecured position due to flaws in documentation,
	o	loans have been restructured so that payment schedules, terms and collateral represent concessions to the borrower when compared to the normal loan terms,
	o	the Corporation is seriously contemplating foreclosure or legal action due to the apparent deterioration of the loan, and
	o	there is significant deterioration in market conditions to which the borrower is highly vulnerable.
•	Doubtful - Loans that have all of the weaknesses of those classified as Substandard. However, based on currently existing facts, conditions and values, these weaknesses make full collection of principal highly questionable and improbable. Other credit characteristics may include the primary source of repayment is gone or there is considerable doubt as to the quality of the secondary sources of repayment. The possibility of loss is high, but because of certain important pending factors that may strengthen the loan, loss classification is deferred until the exact status of repayment is known.
•	Loss – Loans that are considered uncollectible and of such little value that continuing to carry them as an asset is not warranted. Loans will be classified as Loss when it is neither practical not desirable to defer writing off or reserving all or a portion of a basically worthless asset, even though partial recovery may be possible at some time in the future.
The following tables summarize the credit quality of the Corporation’s loan portfolio, by loan class for the years indicated.  Consumer non-performing loans include accruing consumer loans 90 plus days delinquent and consumer non-accrual loans.  The entire balance of a loan is considered delinquent if the minimum payment contractually required to be made is not received by the specified date. Loans that evidenced deterioration of credit quality since origination and it was probable, at acquisition, that all contractually required payments would not be collected are included in the applicable categories below.
	December 31, 2014
	Commercial Pass				Commercial Special Mention			Commercial Substandard			Commercial Doubtful			Commercial Loss		Consumer Performing				Consumer				Total
																				Non Performing
Commercial and industrial loans	$	823,732			$	24,455		$	48,226		$	275												$	896,688
Agriculture production financing and other loans to farmers	96,155				1,195			7,577																104,927
Real estate loans:
Construction	185,394				3,164			2,928								$	15,588			$	147			207,221
Commercial and farmland	1,552,781				29,484			90,161												235				1,672,661
Residential	149,430				6,321			10,918								470,972				9,674				647,315
Home equity	6,368				12			690								277,571				1,888				286,529
Individuals' loans for household and other personal expenditures																73,165				235				73,400
Lease financing receivables, net of unearned income	998							108																1,106
Other loans	35,018																							35,018
Loans	$	2,849,876			$	64,631		$	160,608		$	275				$	837,296			$	12,179			$	3,924,865
	December 31, 2013
	Commercial Pass				Commercial Special Mention			Commercial Substandard			Commercial Doubtful			Commercial Loss		Consumer Performing				Consumer				Total
																				Non Performing
Commercial and industrial loans	$	708,835			$	11,332		$	41,013		$	525												$	761,705
Agriculture production financing and other loans to farmers	114,318							30																114,348
Real estate loans:
Construction	162,976				1,132			12,029												$	945			177,082
Commercial and farmland	1,473,714				57,676			80,184												235				1,611,809
Residential	143,657				2,232			11,494			136					$	448,494			10,372				616,385
Home equity	6,194				35			1,184								246,101				1,709				255,223
Individuals' loans for household and other personal expenditures																69,666				117				69,783
Lease financing receivables, net of unearned income	1,420							125																1,545
Other loans	24,334							195																24,529
Loans	$	2,635,448			$	72,407		$	146,254		$	661				$	764,261			$	13,378			$	3,632,409
The following tables illustrate the past due aging of the Corporation’s loan portfolio, by loan class, for the years indicated:
	December 31, 2014
	Current				30-59 Days			60-89 Days			Loans > 90 Days			Non-Accrual				Total Past Due				Total
					Past Due			Past Due			And Accruing							& Non-Accrual
Commercial and industrial loans	$	882,596			$	4,006		$	53		$	2,985		$	7,048			$	14,092			$	896,688
Agriculture production financing and other loans to farmers	98,236				891									5,800				6,691				104,927
Real estate loans:
Construction	204,683				1,017			82						1,439				2,538				207,221
Commercial and farmland	1,642,016				9,846			778			671			19,350				30,645				1,672,661
Residential	626,821				4,876			1,831			854			12,933				20,494				647,315
Home equity	282,828				1,213			352			148			1,988				3,701				286,529
Individuals' loans for household and other personal expenditures	72,853				258			53			5			231				547				73,400
Lease financing receivables, net of unearned income	1,106																					1,106
Other loans	35,018																					35,018
Loans	$	3,846,157			$	22,107		$	3,149		$	4,663		$	48,789			$	78,708			$	3,924,865
	December 31, 2013
	Current				30-59 Days			60-89 Days			Loans > 90 Days			Non-Accrual				Total Past Due				Total
					Past Due			Past Due			And Accruing							& Non-Accrual
Commercial and industrial loans	$	749,020			$	2,628		$	774					$	9,283			$	12,685			$	761,705
Agriculture production financing and other loans to farmers	114,305				13									30				43				114,348
Real estate loans:
Construction	171,046				1,058									4,978				6,036				177,082
Commercial and farmland	1,573,403				3,807			5,801			$	703		28,095				38,406				1,611,809
Residential	595,192				7,156			1,475			494			12,068				21,193				616,385
Home equity	251,188				1,652			563			153			1,667				4,035				255,223
Individuals' loans for household and other personal expenditures	69,061				550			55						117				722				69,783
Lease financing receivables, net of unearned income	1,545																					1,545
Other loans	24,365													164				164				24,529
Loans	$	3,549,125			$	16,864		$	8,668		$	1,350		$	56,402			$	83,284			$	3,632,409
See the information regarding the analysis of loan loss experience in the “Loan Quality" and "Provision And Allowance For Loan Losses" section of Management’s Discussion and Analysis of Financial Condition and Results of Operations included as Item 7 of this Annual Report on Form 10-K.
On occasion, borrowers experience declines in income and cash flow. As a result, these borrowers seek to reduce contractual cash outlays including debt payments. Concurrently, in an effort to preserve and protect its earning assets, specifically troubled loans, the Corporation is working to maintain its relationship with certain customers who are experiencing financial difficulty by contractually modifying the borrower's debt agreement with the Corporation. In certain loan restructuring situations, the Corporation may grant a concession to a debtor experiencing financial difficulty, resulting in a trouble debt restructuring. A concession is deemed to be granted when, as a result of the restructuring, the Corporation does not expect to collect all original amounts due, including interest accrued at the original contract rate. If the payment of principal at original maturity is primarily dependent on the value of collateral, the current value of the collateral is considered in determining whether the principal will be paid.
The following tables summarize troubled debt restructurings that occurred during the periods ended December 31, 2014 and 2013:
	December 31, 2014
	Pre-Modification				Post-Modification			Number
	Recorded Balance				Recorded Balance			of Loans
Real estate loans:
Commercial and farmland	$	259			$	259		1
Residential	632				622			9
Home equity	320				350			11
Individuals' loans for household and other personal expenditures	26				26			2
Total	$	1,237			$	1,257		23
	December 31, 2013
	Pre-Modification				Post-Modification			Number
	Recorded Balance				Recorded Balance			of Loans
Commercial and industrial loans	$	295			$	316		5
Real estate loans:
Commercial and farmland	6,506				5,492			11
Residential	809				804			12
Individuals' loans for household and other personal expenditures	143				145			4
Total	$	7,753			$	6,757		32
The following tables show the recorded investment of troubled debt restructurings, by modification type, that occurred during the years indicated:
	31-Dec-14
	Term				Rate			Combination			Total
	Modification				Modification						Modification
Real estate loans:
Commercial and farmland	$	288									$	288
Residential	31				$	218		$	360		609
Home equity					100			243			343
Individuals' loans for household and other personal expenditures								23			23
Total	$	319			$	318		$	626		$	1,263
	31-Dec-13
	Term				Rate			Combination			Total
	Modification				Modification						Modification
Commercial and industrial loans	$	207						$	60		$	267
Real estate loans:
Commercial and farmland	1,388							1,985			3,373
Residential	167				$	237		351			755
Individuals' loans for household and other personal expenditures	61				38			25			124
Total	$	1,823			$	275		$	2,421		$	4,519
Loans secured by residential real estate made up 49 percent of the post-modification balances of the troubled debt restructured loans during the twelve months ending December 31, 2014.  The second largest class of troubled debt restructurings during 2014 was home equity real estate loans, which accounted for 28 percent of the total post modification balances.
The following tables summarize troubled debt restructures that occurred during the twelve months ended December 31, 2014 and 2013, that subsequently defaulted during the period indicated and remained in default at period end. For purposes of this schedule, a loan is considered in default if it is 30 or more days past due.
	Twelve Months Ended December 31, 2014
	Number of Loans			Recorded Balance
Real estate loans:
Residential	1			$	70
Total	1			$	70
	Twelve Months Ended December 31, 2013
	Number of Loans			Recorded Balance
Commercial and industrial loans	3			$	173
Real estate loans:
Commercial and farmland	2			1,034
Total	5			$	1,207
For potential consumer loan restructures, impairment evaluation occurs prior to modification. Any subsequent impairment is typically addressed through the charge off process, or may be addressed through a specific reserve. Consumer troubled debt restructurings are generally included in the general historical allowance for loan loss at the post modification balance. Consumer non-accrual and delinquent troubled debt restructurings are also considered in the calculation of the non-accrual and delinquency trend environmental allowance allocation. Commercial troubled debt restructured loans risk graded special mention, substandard, doubtful and loss are individually evaluated for impairment under ASC 310. Any resulting specific reserves are included in the allowance for loan losses. Commercial 30 - 89 day delinquent troubled debt restructurings are included in the calculation of the delinquency trend environmental allowance allocation. All commercial non-impaired loans, including non-accrual and 90+ day delinquents, are included in the ASC 450 loss migration analysis.

Accounting_For_Certain_Loans_A

Accounting For Certain Loans Acquired In a Purchase	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Accounting For Certain Loans Acquired In a Purchase	ACCOUNTING FOR CERTAIN LOANS ACQUIRED IN A PURCHASE
	The Bank acquired loans in a purchase during the years ended December 31, 2014, 2013 and 2012. The acquired loans detailed in the tables below are included in Note 6. LOANS AND ALLOWANCE, in the Notes to Consolidated Financial Statements included as Item 8 of this Annual Report on Form 10-K. As described in Note 6, loans purchased after December 31, 2008 are recorded at the acquisition date fair value, which could result in a fair value discount or premium. Purchased loans with evidence of credit deterioration since origination and for which it is probable at the date of acquisition that the acquirer will not collect all contractually required principal and interest payments are accounted for under ASC 310-30, Loans Acquired with Deteriorated Credit Quality. The difference between contractually required payments and the cash flows expected to be collected at acquisition is referred to as the nonaccretable portion of the fair value discount or premium. The accretable portion of the fair value discount or premium is the difference between the expected cash flows and the net present value of expected cash flows, with such difference accreted into earnings over the term of the loans. All other loans not accounted for under ASC 310-30 are accounted for under ASC 310-20.
	The following table includes the outstanding balance and carrying amount of all the performing and non-performing acquired loans, which are included in the Corporation's balance sheet at December 31, 2014 and 2013.
		31-Dec-14												December 31, 2013
		Community			CFS			SCB			Total			CFS			SCB			Total
	Outstanding Balance:
	Commercial and industrial loans	$	8,168		$	64,897		$	6,059		$	79,124		$	81,303		$	8,184		$	89,487
	Agricultural production financing and other loans to farmers	1,100						893			1,993						1,161			1,161
	Real estate loans:
	Construction	19,063			9,113						28,176			17,962						17,962
	Commercial and farmland	74,600			251,002			15,593			341,195			311,631			23,418			335,049
	Residential	28,863			144,396			7,384			180,643			166,754			9,359			176,113
	Home Equity	9,881			39,244			15,758			64,883			49,042			18,236			67,278
	Individuals' loans for household and other personal expenditures	1,314			922			121			2,357			2,360			269			2,629
	Other Loans				86						86			$	132		$	407		$	539
	Total	$	142,989		$	509,660		$	45,808		$	698,457		$	629,184		$	61,034		$	690,218
	Carrying Amount	$	134,198		$	484,949		$	39,324		$	658,471		$	585,913		$	50,269		$	636,182
	Allowance				650						650						229			229
	Carrying Amount Net of Allowance	$	134,198		$	484,299		$	39,324		$	657,821		$	585,913		$	50,040		$	635,953
	The balance of the allowance for loan losses and the corresponding provision expense for loans acquired and accounted for under ASC310-30 was $650,000 and $229,000 at December 31, 2014 and 2013, respectively.
	As customer cash flow expectations improve, nonaccretable yield can be reclassified to accretable yield. The accretable yield, or income expected to be collected, and reclassifications from nonaccretable yield, are identified in the table below.
		Twelve months ended
		31-Dec-14												31-Dec-13									31-Dec-12
		Community			CFS			SCB			Total			CFS			SCB			Total			SCB
	Beginning balance				$	13,435		$	5,864		$	19,299					$	5,142		$	5,142		$	—
	Additions	$	5,687								5,687			$	13,599					13,599
	Accretion	(394		)	(6,431		)	(2,058		)	(8,883		)	(164		)	(2,071		)	(2,235		)	9,774
	Reclassification from nonaccretable	119			4,501			799			5,419						2,888			2,888			(4,632		)
	Disposals				(1,594		)	(492		)	(2,086		)				(95		)	(95		)	—
	Ending balance	$	5,412		$	9,911		$	4,113		$	19,436		$	13,435		$	5,864		$	19,299		$	5,142
	The following table presents loans acquired during the periods ending December 31, 2014 and 2013, for which it was probable at acquisition that all contractually required payments would not be collected:
		Community - 2014			CFS - 2013
	Contractually required payments receivable at acquisition date	$	26,032		$	109,839
	Nonaccretable difference	3,498			22,679
	Expected cash flows at acquisition date	22,534			87,160
	Accretable difference	2,234			3,502
	Basis in loans at acquisition date	$	20,300		$	83,658

Premises_and_Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Premises and Equipment	PREMISES AND EQUIPMENT
	The following table summarizes the Corporation's premises and equipment as of December 31, 2014 and 2013:
		2014			2013
	Cost at December 31:
	Land	$	19,373		$	17,992
	Buildings and Leasehold Improvements	99,451			92,693
	Equipment	56,606			54,274
	Total Cost	175,430			164,959
	Accumulated Depreciation and Amortization	(97,739		)	(90,505		)
	Net	$	77,691		$	74,454
	The Corporation is committed under various non-cancelable lease contracts for certain subsidiary office facilities and equipment. Total lease expense for 2014, 2013 and 2012 was $3,258,000, $2,608,000 and $2,812,000, respectively. The future minimum rental commitments required under the operating leases in effect at December 31, 2014, expiring at various dates through the year 2028 are as follows for the years ending December 31:
		Future Minimum Rental Commitments
	2015	$	2,778
	2016	2,207
	2017	1,514
	2018	844
	2019	537
	After 2019	2,724
	Total Future Minimum Obligations	$	10,604

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2014
Goodwill Disclosure [Abstract]
Goodwill	GOODWILL
	On November 7, 2014, the Community acquisition resulted in goodwill of $13,776,000. Additionally, on November 12, 2013, the CFS acquisition resulted in goodwill of $47,573,000.
	No impairment loss was recorded in 2014 or 2013. The Corporation tested goodwill for impairment during 2014 and 2013. In both valuations, the fair value exceeded the Corporation’s carrying value; therefore, it was concluded goodwill is not impaired. For additional details related to impairment testing, see the “GOODWILL” section of Management’s Discussion and Analysis of Financial Condition and Results of Operations included as Item 7 of this Annual Report on Form 10-K.
		2014		2013
	Balance, January 1	$	188,948	$	141,375
	Goodwill acquired	13,776		47,573
	Balance, December 31	$	202,724	$	188,948

Core_Deposit_and_Other_Intangi

Core Deposit and Other Intangibles	12 Months Ended
	Dec. 31, 2014
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Core Deposit and Other Intangibles	CORE DEPOSIT AND OTHER INTANGIBLES
	On November 7, 2014, the Community acquisition resulted in a core deposit intangible of approximately $4,658,000. Additionally, on November 12, 2013, the CFS acquisition resulted in a core deposit intangible of approximately $7,313,000.
	The carrying basis and accumulated amortization of recognized core deposit and other intangibles are noted below.
		2014			2013
	Gross carrying amount	$	53,702		$	46,389
	Core deposit intangible and other intangibles acquired	4,658			7,313
	Accumulated amortization	(42,329		)	(39,884		)
	Core Deposit and Other Intangibles	$	16,031		$	13,818
	Amortization expense for the years ended December 31, 2014, 2013 and 2012, was $2,445,000, $1,649,000 and $1,927,000, respectively.
	Estimated future amortization expense is summarized as follows:
		Amortization Expense
	2015	$	2,884
	2016	2,817
	2017	2,723
	2018	1,542
	2019	1,293
	After 2019	4,772
	Total Future Minimum Obligations	$	16,031

Deposits

Deposits	12 Months Ended
	Dec. 31, 2014
Banking and Thrift [Abstract]
Deposits	DEPOSITS
	The composition of the deposit portfolio is included in the table below for the years indicated:
		31-Dec-14		31-Dec-13
	Demand deposits	$	2,146,492	$	2,018,650
	Savings deposits	1,376,707		1,257,994
	Certificates and other time deposits of $100,000 or more	260,685		272,660
	Other certificates and time deposits	523,010		595,110
	Brokered deposits	333,800		87,054
	Total deposits	$	4,640,694	$	4,231,468
	At December 31, 2014, the contractual maturities of time deposits are summarized as follows:
		Certificates and Other Time Deposits
	2015	$	469,352
	2016	256,921
	2017	144,348
	2018	87,234
	2019	52,792
	After 2019	106,848
		$	1,117,495

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Borrowings	BORROWINGS
	The following table summarizes the Corporation's borrowings as of December 31, 2014 and 2013:
		31-Dec-14		31-Dec-13
	Federal funds purchased	$	15,381	$	125,645
	Securities sold under repurchase agreements	124,539		148,672
	Federal Home Loan Bank advances	145,264		122,140
	Subordinated debentures and term loans	126,810		126,807
	Total Borrowings	$	411,994	$	523,264
	Securities sold under repurchase agreements consist of obligations of the Bank to other parties. The obligations are secured by U.S. Treasury and U.S. Government-Sponsored Enterprise obligations, certain municipal securities and mortgage loans. The maximum amount of outstanding agreements at any month-end during 2014 and 2013 totaled $155,941,000 and $161,814,000, respectively, and the average of such agreements totaled $130,910,000 and $140,126,000 during 2014 and 2013, respectively.
	Maturities of securities sold under repurchase agreements; Federal Home Loan Bank Advances, subordinated debentures and term loans as of December 31, 2014, are as follows:
	Maturities in Years Ending December 31:	Securities Sold		Federal Home		Subordinated
		Under Repurchase Agreements		Loan Bank		Debentures and
				Advances		Term Loans
	2015	$	124,539	$	30,780	$	108
	2016			41,225
	2017			15,018
	2018			25,637
	2019			12,503
	After 2019			20,101		126,702
		$	124,539	$	145,264	$	126,810
	The terms of a security agreement with the FHLB require the Corporation to pledge, as collateral for advances, qualifying first mortgage loans, investment securities and multi-family loans in an amount equal to at least 146 percent of these advances depending on the type of collateral pledged. Advances, with interest rates from 0.43 to 6.81 percent, are subject to restrictions or penalties in the event of prepayment. The total available remaining borrowing capacity from the FHLB at December 31, 2014, was $399,188,000.
	Subordinated Debentures and Term Loans. As of December 31, 2014, subordinated debentures and term loans totaled $126,810,000.
	•	First Merchants Capital Trust II. The subordinated debenture, entered into on July 2, 2007, for $56,702,000 will mature on September 15, 2037. The Corporation could not redeem the debenture prior to September 15, 2012, and redemption is subject to the prior approval of the Board of Governors of the Federal Reserve System, as required by law or regulation. Interest was fixed at 6.495 percent for the period from the date of issuance through September 15, 2012; interest is now an annual floating rate equal to the three-month LIBOR plus 1.56 percent, reset quarterly. Interest is payable in March, June, September and December of each year. The interest rate at December 31, 2014 was 1.8 percent. The Corporation holds all of the outstanding common securities of First Merchants Capital Trust II.
	•	On November 1, 2013, the Corporation completed the private issuance and sale to four institutional investors of an aggregate of $70 million of debt comprised of (a) 5.00 percent Fixed-to-Floating Rate Senior Notes due 2028 in the aggregate principal amount of $5 million (the "Senior Debt") and (b) 6.75 percent Fixed-to-Floating Rate Subordinated Notes due 2028 in the aggregate principal amount of $65 million (the "Subordinated Debt"). The interest rate on the Senior Debt and Subordinated Debt remains fixed for the first ten (10) years and will become floating thereafter. The Senior Debt agreement contains certain customary representations and warranties and financial and negative covenants. As of December 31, 2014, the Corporation was in compliance with these covenants. The net proceeds of the placement were used to pay off the Corporation's $55 million credit facility with Bank of America, N.A. which was scheduled to mature on February 15, 2015.
	Line of Credit. As of December 31, 2014, there was no outstanding balance on the line of credit.
	•	U.S. Bank, N.A. On April 11, 2014, the Corporation entered into a line of credit agreement with U.S. Bank, N.A. with a maximum borrowing capacity of $20 million. As of December 31, 2014, there was no outstanding balance on the line of credit. Interest is payable quarterly based on one-month LIBOR plus 2.00 percent. The line of credit has a quarterly facility fee of 0.25 percent on the unused balance. The maturity date for the line of credit is April 10, 2015. The line of credit agreement contains certain customary representations and warranties and financial and negative covenants. As of December 31, 2104, the Corporation was in compliance with these covenants.
	Subordinated Debentures and Term Loans. As of December 31, 2013, subordinated debentures and term loans totaled $126,807,000.
	•	First Merchants Capital Trust II. The subordinated debenture, entered into on July 2, 2007, for $56,702,000 will mature on September 15, 2037. The Corporation could not redeem the debenture prior to September 15, 2012, and redemption is subject to the prior approval of the Board of Governors of the Federal Reserve System, as required by law or regulation. Interest was fixed at 6.495 percent for the period from the date of issuance through September 15, 2012; interest is now an annual floating rate equal to the three-month LIBOR plus 1.56 percent, reset quarterly. Interest is payable in March, June, September and December of each year. The interest rate at December 31, 2013 was 1.7 percent. The Corporation holds all of the outstanding common securities of First Merchants Capital Trust II.
	•	On November 1, 2013, the Corporation completed the private issuance and sale to four institutional investors of an aggregate of $70 million of debt comprised of (a) 5.00 percent Fixed-to-Floating Rate Senior Notes due 2028 in the aggregate principal amount of $5 million (the "Senior Debt") and (b) 6.75 percent Fixed-to-Floating Rate Subordinated Notes due 2028 in the aggregate principal amount of $65 million (the "Subordinated Debt"). The interest rate on the Senior Debt and Subordinated Debt remains fixed for the first ten (10) years and will become floating thereafter. The Senior Debt agreement contains certain customary representations and warranties and financial and negative covenants. As of December 31, 2013, the Corporation was in compliance with these covenants. The net proceeds of the placement were used to pay off the Corporation's $55 million credit facility with Bank of America, N.A. which was scheduled to mature on February 15, 2015.
	•	Bank of America, N.A. The Corporation had a $55 million credit facility with Bank of America, N.A. comprised of (a) a term loan in the principal amount of $5 million (the “Term Loan”) and (b) a subordinated debenture in the principal amount of $50 million (the “Subordinated Debt”).  Pursuant to the terms of the underlying Loan Agreement (the “Loan Agreement”), the Term Loan and the Subordinated Debt would have matured on February 15, 2015.  The Term Loan was secured by a pledge of all of the issued and outstanding shares of the Bank. On November 1, 2013, the Corporation used a portion of the proceeds from the $70 million subordinated debt placement to pay-off the Bank of America $55 million credit facility.

Derivative_Instruments_and_Hed

Derivative Instruments and Hedging Activities

12 Months Ended

Dec. 31, 2014

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments and Hedging Activities

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES

Risk Management Objective of Using Derivatives

The Corporation is exposed to certain risks arising from both its business operations and economic conditions.  The Corporation principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Corporation manages economic risks, including interest rate, liquidity, and credit risk, primarily by managing the amount, sources, and duration of its assets and liabilities and through the use of derivative financial instruments.  Specifically, the Corporation enters into derivative financial instruments to manage exposures that arise from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates.  The Corporation’s derivative financial instruments are used to manage differences in the amount, timing, and duration of the Corporation’s known or expected cash payments principally related to certain variable-rate liabilities.  The Corporation also has derivatives that are a result of a service the Corporation provides to certain qualifying customers, and, therefore, are not used to manage interest rate risk in the Corporation’s assets or liabilities.  The Corporation manages a matched book with respect to its derivative instruments offered as a part of this service to its customers in order to minimize its net risk exposure resulting from such transactions.

Fair Values of Derivative Instruments on the Balance Sheet

The table below presents the fair value of the Corporation’s derivative financial instruments as well as their classification on the Balance Sheet as of December 31, 2014 and December 31, 2013.

Asset Derivatives

Liability Derivatives

December 31, 2014

December 31, 2013

December 31, 2014

December 31, 2013

Balance Sheet Location

Fair

Balance Sheet Location

Fair

Balance Sheet Location

Fair

Balance Sheet Location

Fair

Value

Value

Value

Value

Derivatives designated as hedging instruments:

Interest rate contracts

Other Assets

$

137

Other Assets

$

1,162

Other Liabilities

$

2,650

Other Liabilities

$

1,021

Derivatives not designated as hedging instruments:

Interest rate contracts

Other Assets

$

3,730

Other Assets

$

2,847

Other Liabilities

$

3,887

Other Liabilities

$

2,932

Cash Flow Hedges of Interest Rate Risk

The Corporation’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish this objective, the Corporation primarily uses interest rate swaps and interest rate caps as part of its interest rate risk management strategy.  Interest rate swaps designated as cash flow hedges involve the payment of fixed amounts to a counterparty in exchange for the Corporation receiving variable payments over the life of the agreements without exchange of the underlying notional amount. Interest rate caps designated as cash flow hedges involve the receipt of variable amounts from a counterparty if interest rates rise above the strike rate on the contract in exchange for an up-front premium.  As of December 31, 2014 and 2013, the Corporation had five interest rate swaps with a notional amount of $56.0 million and one interest rate cap with a notional amount of $13.0 million.

The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in accumulated other comprehensive income and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. During 2014, $26.0 million of the interest rate swaps and the $13.0 million interest rate cap were used to hedge the variable cash outflows (LIBOR-based) associated with existing trust preferred securities when the outflows converted from a fixed rate to variable rate in September 2012.  In addition, the remaining $30.0 million of interest rate swaps were used to hedge the variable cash outflows (LIBOR-based) associated with three Federal Home Loan Bank advances. The ineffective portion of the change in fair value of the derivatives is recognized directly in earnings. During the years ended December 31, 2014 and 2013, the Corporation did not recognize any ineffectiveness.

Amounts reported in accumulated other comprehensive income related to derivatives will be reclassified to interest expense as interest payments are made on the Corporation’s variable-rate liabilities.  During the next twelve months, the Corporation expects to reclassify $1,341,000 from accumulated other comprehensive income to interest expense.

Non-designated Hedges

The Corporation does not use derivatives for trading or speculative purposes.  Derivatives not designated as hedges are not speculative and result from a service the Corporation provides to certain customers. The Corporation executes interest rate swaps with commercial banking customers to facilitate their respective risk management strategies.  Those interest rate swaps are simultaneously hedged by offsetting interest rate swaps that the Corporation executes with a third party, such that the Corporation minimizes its net risk exposure resulting from such transactions.  As the interest rate swaps associated with this program do not meet the strict hedge accounting requirements, changes in the fair value of both the customer swaps and the offsetting swaps are recognized directly in earnings.  As of December 31, 2014, the notional amount of customer-facing swaps was approximately $155,891,000.  This amount is offset with third party counterparties, as described above.

Effect of Derivative Instruments on the Income Statement

The tables below present the effect of the Corporation’s derivative financial instruments on the Income Statement for the years ended December 31, 2014, 2013 and 2012.

Derivatives Not

Location of Gain

Amount of Gain (Loss)

Amount of Gain (Loss)

Amount of Gain (Loss)

Designated as Hedging

(Loss) Recognized in

Recognized in Income on

Recognized in Income on

Recognized in Income on

Instruments under

Income on Derivative

Derivative for the Year Ended December 31, 2014

Derivative for the Year Ended December 31, 2013

Derivative for the Year Ended December 31, 2012

FASB ASC 815-10

Interest rate contracts

Other income

$

(73

)

$

247

$

(79

)

Derivatives in Cash Flow Hedging Relationships

Amount of Gain (Loss) Recognized in Other Comprehensive Income on Derivative

Location of Loss Reclassified from Accumulated Other Comprehensive Income (Effective Portion)

Amount of Loss Reclassified from Other Comprehensive Income into Income

(Effective Portion)

(Effective Portion)

For the Year Ended

For the Year Ended

2014

2013

2014

2013

2012

Interest rate products

$

(3,996

)

$

2,374

Interest expense

$

(1,411

)

$

(935

)

$

(217

)

The Corporation’s exposure to credit risk occurs because of nonperformance by its counterparties.  The counterparties approved by the Corporation are usually financial institutions, which are well capitalized and have credit ratings through Moody’s and/or Standard & Poor’s, at or above investment grade.  The Corporation’s control of such risk is through quarterly financial reviews, comparing mark-to-market values with policy limitations, credit ratings and collateral pledging.

Credit-Risk-Related Contingent Features

The Corporation has agreements with certain of its derivative counterparties that contain a provision where if the Corporation fails to maintain its status as a well/adequately capitalized institution, then the Corporation could be required to terminate or fully collateralize all outstanding derivative contracts. Additionally, the Corporation has agreements with certain of its derivative counterparties that contain a provision where if the Corporation defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then the Corporation could also be declared in default on its derivative obligations. As of December 31, 2014, the termination value of derivatives in a net liability position related to these agreements was $6,785,000. As of December 31, 2014, the Corporation has minimum collateral posting thresholds with certain of its derivative counterparties and has posted collateral of $7,411,000. If the Corporation had breached any of these provisions at December 31, 2014, it could have been required to settle its obligations under the agreements at their termination value.

Fair_Values_of_Financial_Instr

Fair Values of Financial Instruments	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Values of Financial Instruments	FAIR VALUES OF FINANCIAL INSTRUMENTS
	The Corporation used fair value measurements to record fair value adjustments, to certain assets, and liabilities and to determine fair value disclosures. The accounting guidance defines fair value, establishes a framework for measuring fair value and expands disclosures about fair value measurements.  ASC 820 applies only when other guidance requires or permits assets or liabilities to be measured at fair value; it does not expand the use of fair value in any new circumstances.
	As defined in ASC 820, fair value is the price to sell an asset or transfer a liability in an orderly transaction between market participants. It represents an exit price at the measurement date. Market participants are buyers and sellers, who are independent, knowledgeable, and willing and able to transact in the principal (or most advantageous) market for the asset or liability being measured. Current market conditions, including imbalances between supply and demand, are considered in determining fair value. The Corporation values its assets and liabilities in the principal market where it sells the particular asset or transfers the liability with the greatest volume and level of activity. In the absence of a principal market, the valuation is based on the most advantageous market for the asset or liability (i.e., the market where the asset could be sold or the liability transferred at a price that maximizes the amount to be received for the asset or minimizes the amount to be paid to transfer the liability).
	Valuation inputs refer to the assumptions market participants would use in pricing a given asset or liability. Inputs can be observable or unobservable. Observable inputs are those assumptions which market participants would use in pricing the particular asset or liability. These inputs are based on market data and are obtained from a source independent of the Corporation. Unobservable inputs are assumptions based on the Corporation’s own information or estimate of assumptions used by market participants in pricing the asset or liability. Unobservable inputs are based on the best and most current information available on the measurement date. All inputs, whether observable or unobservable, are ranked in accordance with a prescribed fair value hierarchy which gives the highest ranking to quoted prices (unadjusted) in active markets for identical assets or liabilities (Level 1) and the lowest ranking to unobservable inputs for which there is little or no market activity (Level 3). Fair values for assets or liabilities classified as Level 2 are based on one or a combination of the following factors: (i) quoted prices for similar assets; (ii) observable inputs for the asset or liability, such as interest rates or yield curves; or (iii) inputs derived principally from or corroborated by observable market data. The level in the fair value hierarchy within which the fair value measurement in its entirety falls is determined based on the lowest level input that is significant to the fair value measurement in its entirety. The Corporation considers an input to be significant if it drives 10 percent or more of the total fair value of a particular asset or liability.
	RECURRING MEASUREMENTS
	Assets and liabilities are considered to be measured at fair value on a recurring basis if fair value is measured regularly (i.e., daily, weekly, monthly or quarterly). Recurring valuation occurs at a minimum on the measurement date. Assets and liabilities are considered to be measured at fair value on a nonrecurring basis if the fair value measurement of the instrument does not necessarily result in a change in the amount recorded on the balance sheet. Generally, nonrecurring valuation is the result of the application of other accounting pronouncements which require assets or liabilities to be assessed for impairment or recorded at the lower of cost or fair value. The fair value of assets or liabilities transferred in or out of Level 3 is measured on the transfer date, with any additional changes in fair value subsequent to the transfer considered to be realized or unrealized gains or losses.
	Following is a description of the valuation methodologies used for instruments measured at fair value on a recurring basis and recognized in the accompanying balance sheet, as well as the general classification of such instruments pursuant to the valuation hierarchy.
	Investment Securities
	Where quoted, market prices are available in an active market and securities are classified within Level 1 of the valuation hierarchy. There are no securities classified within Level 1 of the hierarchy. If quoted market prices are not available, then fair values are estimated by using pricing models, quoted prices of securities with similar characteristics or discounted cash flows. Level 2 securities include agencies, government-sponsored mortgage backs, state and municipal and equity securities. In certain cases where Level 1 or Level 2 inputs are not available, securities are classified within Level 3 of the hierarchy and include state and municipal, corporate obligations and equity securities. Level 3 fair value on state and municipal, corporate obligations and equity securities was determined using a discounted cash flow model that incorporated market estimates of interest rates and volatility in markets that have not been active.
	Third party vendors compile prices from various sources and may apply such techniques as matrix pricing to determine the value of identical or similar investment securities (Level 2). Matrix pricing is a mathematical technique widely used in the banking industry to value investment securities without relying exclusively on quoted prices for specific investment securities but rather relying on the investment securities’ relationship to other benchmark quoted investment securities. Any investment security not valued based upon the methods above are considered Level 3.
	Corporate Obligations
	In 2013, the Corporation’s corporate obligations consisted primarily of pooled trust preferred securities. The issuers of these securities were primarily banks, but some of the pools did include a limited number of insurance companies. The Corporation used an other-than-temporary ("OTTI") evaluation process to compare the present value of expected cash flows to determine whether an adverse change in cash flows had occurred. The OTTI process considered the structure and term of the collateralized debt obligation ("CDO") and the financial condition of the underlying issuers. Specifically, the process detailed interest rates, principal balances of note classes and underlying issuers, the timing and amount of interest and principal payments of the underlying issuers, and the allocation of the payments to the note classes. The estimated expected cash flows were based on the most recent trustee reports and any other relevant market information including announcements of interest payment deferrals or defaults of underlying trust preferred securities. In 2014, the Corporation sold all but one of its trust preferred securities, which resulted in gains of $1.9 million. These securities had previous OTTI of $9.4 million. The one remaining trust preferred security has no remaining book value as a result of OTTI of approximately $500,000 taken in 2009.
	Interest Rate Derivative Agreements
	See information regarding the Corporation’s interest rate derivative products in Note 13. DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES, in the Notes to Consolidated Financial Statements included as Item 8 of this Annual Report on Form 10-K.
	The following table presents the fair value measurements of assets and liabilities recognized in the accompanying balance sheets measured at fair value on a recurring basis and the level within the ASC 820-10 fair value hierarchy in which the fair value measurements fall at December 31, 2014 and 2013.
							Fair Value Measurements Using:
							Quoted Prices in Active		Significant Other Observable Inputs				Significant
							Markets for Identical Assets						Unobservable Inputs
	December 31, 2014		Fair Value				(Level 1)		(Level 2)				(Level 3)
	Available for sale securities:
	U.S. Government-sponsored agency securities		$	109					$	109
	State and municipal		228,593						221,982				$	6,611
	U.S. Government-sponsored mortgage-backed securities		319,104						319,104
	Corporate obligations		31										31
	Equity securities		1,706						1,702				4
	Interest rate swap asset		3,730						3,730
	Interest rate cap		137						137
	Interest rate swap liability		6,537						6,537
							Fair Value Measurements Using:
							Quoted Prices in Active		Significant Other Observable Inputs				Significant
							Markets for Identical Assets						Unobservable Inputs
	December 31, 2013		Fair Value				(Level 1)		(Level 2)				(Level 3)
	Available for sale securities:
	U.S. Treasury		$	15,973					$	15,973
	U.S. Government-sponsored agency securities		3,545						3,545
	State and municipal		230,987						223,752				$	7,235
	U.S. Government-sponsored mortgage-backed securities		281,252						281,252
	Corporate obligations		2,738										2,738
	Equity securities		1,706						1,702				4
	Interest rate swap asset		3,619						3,619
	Interest rate cap		390						390
	Interest rate swap liability		3,953						3,953
	LEVEL 3 RECONCILIATION
	The following is a reconciliation of the beginning and ending balances of recurring fair value measurements recognized in the accompanying balance sheets using significant unobservable Level 3 inputs for year ended December 31, 2014 and 2013.
		Available for Sale Securities
		For The Year Ended
		December 31, 2014				December 31, 2013
	Beginning Balance	$	9,977			$	18,328
	Included in other comprehensive income	3,656				1,330
	Purchases, issuances, and settlements					7,590
	Transfers in/(out) of Level 3					(16,434		)
	Principal payments	(6,987		)		(837		)
	Ending balance	$	6,646			$	9,977
	There were no gains or losses for the period included in earnings that were attributable to the changes in unrealized gains or losses related to assets or liabilities held at December 31, 2014 or 2013.
	TRANSFERS BETWEEN LEVELS
		Quoted Prices in Active		Significant Other Observable Inputs				Significant
		Markets for Identical Assets						Unobservable Inputs
	31-Dec-13	(Level 1)		(Level 2)				(Level 3)				Reason for Transfer
	Transfers to/(from) Level:
	Available for sale securities			$	(350	)		$	350			Selected state and municipal securities were transferred from Level 2 to Level 3 due to limited availability of similar securities in active markets.
	Available for sale securities transferred to held to maturity							$	(16,784	)		Selected state and municipal securities were transferred from available for sale to held to maturity. These securities are valued at amortized cost and are no longer classified within the fair value hierarchy.
	In 2013, approximately $350,000 of selected state and municipal securities were transferred from Level 2 to Level 3 due to limited availability of similar securities in active markets. Additionally, the Corporation transferred $16,784,000 of selected state and municipal securities from available for sale to held to maturity. These securities are valued at amortized cost and are no longer classified within the fair value hierarchy. All securities transferred to held to maturity were previously classified as Level 3 in the fair value hierarchy. There were no transfers in or out of Level 3 during 2014.
	NONRECURRING MEASUREMENTS
	Following is a description of valuation methodologies used for instruments measured at fair value on a non-recurring basis and recognized in the accompanying balance sheets, as well as the general classification of such instruments pursuant to the valuation hierarchy for year ended December 31, 2014 and 2013.
						Fair Value Measurements Using
						Quoted Prices in Active		Significant Other Observable Inputs		Significant
						Markets for Identical Assets				Unobservable Inputs
December 31, 2014		Fair Value				(Level 1)		(Level 2)		(Level 3)
Impaired Loans (collateral dependent)		$	17,134							$	17,134
Other real estate owned		$	5,155							$	5,155
						Fair Value Measurements Using
						Quoted Prices in Active		Significant Other Observable Inputs		Significant
						Markets for Identical Assets				Unobservable Inputs
December 31, 2013		Fair Value				(Level 1)		(Level 2)		(Level 3)
Impaired Loans (collateral dependent)		$	12,117							$	12,117
Other real estate owned		$	6,877							$	6,877
Impaired Loans (collateral dependent)
Loans for which it is probable that the Corporation will not collect all principal and interest due according to contractual terms are measured for impairment. Allowable methods for determining the amount of impairment include estimating fair value of the collateral for collateral dependent loans. If the impaired loan is identified as collateral dependent, then the fair value method of measuring the amount of impairment is utilized. This method requires obtaining a current independent appraisal of the collateral and applying a discount factor to the value. A portion of the allowance for loan losses is allocated to impaired loans if the value of such loans is deemed to be less than the unpaid balance. If these allocations cause the allowance for loan losses to increase, such increase is reported as a component of the provision for loan losses. Loan losses are charged against the allowance when management believes the uncollectability of the loan is confirmed. During 2014, certain impaired loans were partially charged off or re-evaluated. Impaired loans that are collateral dependent are classified within Level 3 of the fair value hierarchy when impairment is determined using the fair value method.
Other Real Estate Owned
The fair value for impaired loans and other real estate owned is measured based on the value of the collateral securing those loans or real estate and is determined using several methods. The fair value of real estate is generally determined based on appraisals by qualified licensed appraisers. The appraisers typically determine the value of the real estate by utilizing an income or market valuation approach. If an appraisal is not available, the fair value may be determined by using a cash flow analysis. Fair value on other collateral such as business assets is typically ascertained by assessing, either singularly or some combination of,  asset appraisals, accounts receivable aging reports, inventory listings and or customer financial statements. Both appraised values and values based on borrower’s financial information are discounted as considered appropriate based on age and quality of the information and current market conditions.
UNOBSERVABLE (LEVEL 3) INPUTS
The following table presents quantitative information about unobservable inputs used in recurring and nonrecurring Level 3 fair value measurements, other than goodwill, at December 31, 2014 and 2013.
December 31, 2014	Fair Value				Valuation Technique		Unobservable Inputs		Range (Weighted-Average)
State and municipal securities	$	6,611			Discounted cash flow		Maturity Call Date		1 month to 15 years
							US Muni BQ curve		A- to BBB-
							Discount rate		.90% - 5%
Corporate obligations and Equity securities	$	35			Discounted cash flow		Risk free rate		3 month LIBOR
							plus Premium for illiquidity		plus 200 bps
Impaired loans (collateral dependent)	$	17,134			Collateral based measurements		Discount to reflect current market conditions and ultimate collectability		0% - 50% (3%)
Other real estate owned	$	5,155			Appraisals		Discount to reflect current market conditions		0% - 20% (7%)
December 31, 2013	Fair Value				Valuation Technique		Unobservable Inputs		Range (Weighted-Average)
State and municipal securities	$	7,235			Discounted cash flow		Maturity Call Date		1 month to 15 years
							US Muni BQ curve		A- to BBB-
							Discount rate		1% - 5%
Corporate obligations and Equity securities	$	2,742			Discounted cash flow		Risk free rate		3 month LIBOR
							plus Premium for illiquidity		plus 200 bps
Impaired loans (collateral dependent)	$	12,117			Collateral based measurements		Discount to reflect current market conditions and ultimate collectability		0% - 50% (3%)
Other real estate owned	$	6,877			Appraisals		Discount to reflect current market conditions		0% - 20% (2%)
The following is a discussion of the sensitivity of significant unobservable inputs, the interrelationships between those inputs and other unobservable inputs used in recurring fair value measurement and how those inputs might magnify or mitigate the effect of changes in the unobservable inputs on the fair value measurement.
State and Municipal Securities, Corporate Obligations and Equity Securities
The significant unobservable inputs used in the fair value measurement of the Corporation's state and municipal securities, corporate obligations and equity securities are premiums for unrated securities and marketability discounts. Significant increases or decreases in either of those inputs in isolation would result in a significantly lower or higher fair value measurement. Generally, changes in either of those inputs will not affect the other input.
FAIR VALUE OF FINANCIAL INSTRUMENTS
The following table presents estimated fair values of the Corporation's financial instruments and the level within the fair value hierarchy in which the fair value measurements fall at December 31, 2014 and 2013.
	2014
	Carrying				Quoted Prices in Active Markets for Identical Assets				Significant Other Observable Inputs				Significant Unobservable Inputs
	Amount				(Level 1)				(Level 2)				(Level 3)
Assets at December 31:
Cash and cash equivalents	$	118,616			$	118,616
Interest-bearing time deposits	47,520				47,520
Investment securities available for sale	549,543								$	542,897			$	6,646
Investment securities held to maturity	631,088								614,457				33,266
Loans held for sale	7,235								7,235
Loans	3,860,901												3,810,912
FRB and FHLB stock	41,353								41,353
Interest rate swap asset	3,867								3,867
Interest receivable	19,984								19,984
Liabilities at December 31:
Deposits	$	4,640,694			$	3,523,199			$	1,099,610
Borrowings:
Federal funds purchased	15,381								15,381
Securities sold under repurchase agreements	124,539								124,539
FHLB Advances	145,264								146,669
Subordinated debentures and term loans	126,810								92,802
Interest rate swap liability	6,537								6,537
Interest payable	3,201								3,201
	2013
	Carrying				Quoted Prices in Active Markets for Identical Assets				Significant Other Observable Inputs				Significant Unobservable Inputs
	Amount				(Level 1)				(Level 2)				(Level 3)
Assets at December 31:
Cash and cash equivalents	$	109,434			$	109,434
Interest-bearing time deposits	55,069				55,069
Investment securities available for sale	536,201								$	526,224			$	9,977
Investment securities held to maturity	559,378								525,998				34,849
Loans held for sale	5,331								5,331
Loans	3,564,539												3,506,615
FRB and FHLB stock	38,990								38,990
Interest rate swap asset	4,009								4,009
Interest receivable	18,672								18,672
Liabilities at December 31:
Deposits	$	4,231,468			$	3,082,117			$	934,937
Borrowings:
Federal funds purchased	125,645								125,645
Securities sold under repurchase agreements	148,672								148,852
FHLB Advances	122,140								122,962
Subordinated debentures and term loans	126,807								82,607
Interest rate swap liability	3,953								3,953
Interest payable	1,771								1,771
The following methods were used to estimate the fair value of all other financial instruments recognized in the Consolidated Condensed Balance Sheets at amounts other than fair value.
Cash and cash equivalents:  The fair value of cash and cash equivalents approximates carrying value.
Interest-bearing time deposits:  The fair value of interest-bearing time deposits approximates carrying value.
Investment securities:  Fair value is based on quoted market prices, if available.  If a quoted market price is not available, fair value is estimated using quoted market prices for similar securities. The fair value of certain Level III securities is estimated using discounted cash flow analysis, using interest rates currently being offered on investments with similar maturities and investment quality.
Mortgage loans held for sale:  The carrying amount approximates fair value due to the short duration between origination and date of sale.
Loans:  The fair value for loans is estimated using discounted cash flow analysis, using interest rates currently being offered for loans with similar terms to borrowers of similar credit quality.  See Impaired Loans above.
Federal Reserve and Federal Home Loan Bank stock:  The fair value of Federal Reserve Bank and Federal Home Loan Bank stock is based on the price which it may be resold to the Federal Reserve and Federal Home Loan Bank.
Derivative instruments:  The fair value of interest rate swaps reflect the estimated amounts that would have been received to terminate these contracts at the reporting date based upon pricing or valuation models applied to current market information.  Interest rate caps are valued using the market standard methodology of discounting the future expected cash receipts that would occur if variable interest rates rose above the strike rate of the caps.  The projected cash receipts on the caps are based on an expectation of future interest rates derived from observed market interest rate curves and volatilities.
Interest receivable and Interest payable:  The fair value of interest receivable/payable approximates carrying value.
Deposits:  The fair values of noninterest-bearing and interest-bearing demand accounts and savings deposits are equal to the amount payable on demand at the balance sheet date. The carrying amounts for variable rate, fixed-term certificates of deposit approximate their fair values at the balance sheet date. Fair values for fixed-rate certificates of deposit and other time deposits are estimated using a discounted cash flow calculation that applies interest rates currently being offered to a schedule of aggregated expected monthly maturities on such time deposits.
Borrowings:  The fair value of Federal Funds purchased approximates the carrying amount. The fair value of all other borrowings is estimated using a discounted cash flow calculation, based on current rates for similar debt.

Commitments_and_Contingent_Lia

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	COMMITMENTS AND CONTINGENT LIABILITIES
	In the normal course of business there are outstanding commitments and contingent liabilities, such as commitments to extend credit and standby letters of credit, which are not included in the accompanying financial statements.  The Corporation's exposure to credit loss in the event of nonperformance by the other party to the financial instruments for commitments to extend credit and standby letters of credit is represented by the contractual or notional amount of those instruments.  The Bank uses the same credit policies in making such commitments as they do for instruments that are included in the consolidated balance sheets.
	Financial instruments, whose contract amount represents credit risk as of December 31, were as follows:
		2014		2013
	Amounts of commitments:
	Loan commitments to extend credit	$	1,617,552	$	1,216,470
	Standby letters of credit	$	52,655	$	41,508
	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.  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.  The Bank evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if deemed necessary by the Bank upon extension of credit, is based on management's credit evaluation.  Collateral held varies, but may include accounts receivable, inventory, property and equipment, and income-producing commercial properties.
	Standby letters of credit are conditional commitments issued by the Bank to guarantee the performance of a customer to a third party.
	The Corporation and subsidiaries are also subject to claims and lawsuits, which arise primarily in the ordinary course of business.  It is the opinion of management that the disposition or ultimate resolution of such claims and lawsuits will not have a material adverse effect on the consolidated financial position of the Corporation.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Stockholders' Equity	STOCKHOLDERS' EQUITY
	National banking laws restrict the maximum amount of dividends that a bank may pay in any calendar year.  National banks are limited to the bank’s retained net income (as defined) for the current year plus those for the previous two years.  The amount at December 31, 2014, available for 2015 dividends from the Corporation’s subsidiaries (both banking and non-banking) was $23,340,000.
	Total stockholders' equity for all subsidiaries at December 31, 2014, was $818,420,000 of which $795,080,000 was restricted from dividend distribution to the Corporation.
	The Corporation has a Dividend Reinvestment and Stock Purchase Plan, enabling stockholders to elect to have their cash dividends on all shares automatically reinvested in additional shares of the Corporation’s common stock. In addition, stockholders may elect to make optional cash payments up to an aggregate of $2,500 per quarter for the purchase of additional shares of common stock.  The stock is credited to participant accounts at fair market value.  Dividends are reinvested on a quarterly basis.
	Preferred Stock
	On September 22, 2011, the Corporation entered into a Securities Purchase Agreement (the “Purchase Agreement”) with the Treasury, pursuant to which the Corporation issued 90,782.94 shares of the Corporation’s Senior Non-Cumulative Perpetual Preferred Stock, Series B (the “Series B Preferred Stock”), having a liquidation amount per share equal to $1,000, for a total purchase price of $90,782,940. The Purchase Agreement was entered into, and the Series B Preferred Stock was issued, pursuant to the SBLF program, a $30 billion fund established under the Small Business Jobs Act of 2010, that encourages lending to small businesses by providing capital to qualified community banks with assets of less than $10 billion.
	On January 3, 2013, the Corporation redeemed 22,695.94 shares of the Series B Preferred Stock held by the Treasury at an aggregate redemption price of $22,695,940 plus accrued but unpaid dividends. Following the redemption, the Treasury held 68,087 shares of the Series B Preferred Stock representing a remaining liquidation amount of approximately $68 million.
	On July 2, 2013, the Corporation redeemed an additional 34,044 shares of the Series B Preferred Stock held by the Treasury at an aggregate redemption price of $34,044,000 plus accrued but unpaid dividends. Following the redemption, the Treasury held 34,043 shares of the Series B Preferred Stock representing a remaining liquidation amount of approximately $34 million.
	On November 22, 2013, the Corporation redeemed the final 34,043 shares of the Series B Preferred Stock held by the Treasury at an aggregate redemption price of $34,043,000 plus accrued but unpaid dividends. There are no shares of the Corporation's Series B Preferred Stock currently outstanding.
	CFS Acquisition
	On November 12, 2013, the Corporation acquired 100 percent of CFS Bancorp, Inc. ("CFS") in an all stock transaction. Pursuant to the merger agreement, the shareholders of CFS received 0.65 percent of a share of the Corporation's common stock for each share of CFS Bancorp common stock held. The Corporation issued approximately 7.1 million shares of common stock, which was valued at approximately $135.6 million.
	Community Acquisition
	On November 7, 2014, the Corporation acquired 100 percent of Community Bancshares, Inc. ("Community"). Pursuant to the merger agreement, each outstanding share of common stock of Community was converted into the right to receive either (a) 4.0926 shares of First Merchants' common stock, plus cash in lieu of fractional shares; or (b) $85.94 in cash, based upon shareholder elections. The Corporation paid $14.2 million in cash and issued approximately 1.6 million shares of common stock, valued at approximately $35.0 million, for a total purchase price of approximately $49.2 million.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)
	The following table summarizes the changes in the balances of each component of accumulated other comprehensive income (loss), net of tax, as of December 31, 2014 and 2013:
		Accumulated Other Comprehensive Income (Loss)
		Unrealized Gains (Losses) on Securities Available for Sale			Unrealized Gains (Losses) on Securities Available for Sale for which a Portion of Other-Than-Temporary Impairment has been Recognized in Income			Unrealized Gains (Losses) on Cash Flow Hedges			Unrealized Gains (Losses) on Defined Benefit Plans			Total
	Balance at December 31, 2013	$	1,566		$	(1,847	)	$	(501	)	$	(5,628	)	$	(6,410	)
	Other comprehensive income before reclassifications	14,860			1,847			(2,599		)	(7,580		)	6,528
	Amounts reclassified from accumulated other comprehensive income	(2,328		)				918			(338		)	(1,748		)
	Period change	12,532			1,847			(1,681		)	(7,918		)	4,780
	Balance at December 31, 2014	$	14,098		$	—		$	(2,182	)	$	(13,546	)	$	(1,630	)
	Balance at December 31, 2012	$	17,904		$	(3,272	)	$	(2,652	)	$	(17,479	)	$	(5,499	)
	Other comprehensive income before reclassifications	(16,021		)	1,425			1,543			10,704			(2,349		)
	Amounts reclassified from accumulated other comprehensive income	(317		)				608			1,147			1,438
	Period change	(16,338		)	1,425			2,151			11,851			(911		)
	Balance at December 31, 2013	$	1,566		$	(1,847	)	$	(501	)	$	(5,628	)	$	(6,410	)
	The following table presents the reclassification adjustments out of accumulated other comprehensive income (loss) that were included in net income in the Consolidated Condensed Statements of Income for the twelve months ended December 31, 2014, 2013 and 2012:
		Amount Reclassified from Accumulated Other Comprehensive Income (Loss) For the Year Ended December 31,
	Details about Accumulated Other Comprehensive Income (Loss) Components	2014			2013			2012			Affected Line Item in the Statements of Income
	Unrealized gains (losses) on available for sale securities (1)
	Realized securities gains reclassified into income	$	3,581		$	487		$	2,389		Other income - net realized gains on sales of available for sale securities
	Related income tax expense	(1,253		)	(170		)	(835		)	Income tax expense
		$	2,328		$	317		$	1,554
	Unrealized gains (losses) on cash flow hedges (2)
	Interest rate contracts	$	(1,411	)	$	(935	)	$	(217	)	Interest expense - subordinated debentures and term loans
	Related income tax benefit	493			327			76			Income tax expense
		$	(918	)	$	(608	)	$	(141	)
	Unrealized gains (losses) on defined benefit plans
	Amortization of net loss and prior service costs	$	520		$	(1,765	)	$	100		Other expenses - salaries and employee benefits
	Related income tax benefit (expense)	(182		)	618			(35		)	Income tax expense
		$	338		$	(1,147	)	$	65
	Total reclassifications for the period, net of tax	$	1,748		$	(1,438	)	1,478
	(1) For additional detail related to unrealized gains (losses) on available for sale securities and related amounts reclassified from accumulated other comprehensive income see Note 5. INVESTMENT SECURITIES.
	(2) For additional detail related to unrealized gains (losses) on cash flow hedges and related amounts reclassified from accumulated other comprehensive income see Note 13. DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES.

Regulatory_Capital

Regulatory Capital	12 Months Ended
	Dec. 31, 2014
Banking and Thrift [Abstract]
Regulatory Capital	REGULATORY CAPITAL
	The Corporation and the Bank are subject to various regulatory capital requirements administered by the federal banking agencies and are assigned to a capital category.  The assigned capital category is largely determined by three ratios that are calculated according to the regulations: total risk adjusted capital, Tier 1 capital, and Tier 1 leverage ratios. The ratios are intended to measure capital relative to assets and credit risk associated with those assets and off-balance sheet exposures of the entity.  The capital category assigned to an entity can also be affected by qualitative judgments made by regulatory agencies about the risk inherent in the entity's activities that are not part of the calculated ratios.
	There are five capital categories defined in the regulations, ranging from well capitalized to critically undercapitalized. Classification of a bank in any of the undercapitalized categories can result in actions by regulators that could have a material effect on a bank's operations.
	At December 31, 2014, the management of the Corporation believes that it meets all capital adequacy requirements to which it is subject. The most recent notifications from the regulatory agencies categorized the Bank as well capitalized under the regulatory framework for prompt corrective action.  To be categorized as well capitalized, a bank must maintain a minimum total capital to risk-weighted assets, Tier I capital to risk-weighted assets and Tier I capital to average assets of 10 percent, 6 percent and 5 percent, respectively.  It should be noted that a bank's capital category is determined solely for the purpose of applying the OCC's "prompt corrective action" regulations and that the capital category may not constitute an accurate representation of the Bank's overall financial condition or prospects.
	Actual and required capital amounts and ratios are listed below.
		2014								2013
						Required For								Required For
		Actual				Adequate Capital				Actual				Adequate Capital
	December 31,	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
	Total Capital (to Risk-weighted Assets)
	First Merchants Corporation	$	685,507	15.34	%	$	357,581	8	%	$	599,966	14.54	%	$	330,107	8	%
	First Merchants Bank	653,169		14.64		356,884		8		599,272		14.56		329,344		8
	Tier I Capital (to Risk-weighted Assets)
	First Merchants Corporation	$	564,535	12.63	%	$	178,791	4	%	$	483,186	11.71	%	$	165,053	4	%
	First Merchants Bank	597,305		13.39		178,442		4		547,655		13.3		164,672		4
	Tier I Capital (to Average Assets)
	First Merchants Corporation	$	564,535	10.15	%	$	222,533	4	%	$	483,186	10.2	%	$	189,485	4	%
	First Merchants Bank	597,305		10.56		226,339		4		547,655		11.58		189,095		4

Loan_Servicing

Loan Servicing	12 Months Ended
	Dec. 31, 2014
Banking and Thrift [Abstract]
Loan Servicing	LOAN SERVICING
	Mortgage loans serviced for others are not included in the accompanying consolidated balance sheets.  The loans are serviced primarily for the Federal Home Loan Mortgage Corporation and Fannie Mae, and the unpaid balances totaled $254,223,000, $271,871,000 and $167,879,000 at December 31, 2014, 2013 and 2012, respectively.  The amount of capitalized servicing assets is considered immaterial.

ShareBased_Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	SHARE-BASED COMPENSATION
	Stock options and restricted stock awards ("RSAs") have been issued to directors, officers and other management employees under the Corporation's 1999 Long-term Equity Incentive Plan and the 2009 Long-term Equity Incentive Plan.  The stock options, which have a ten-year life, become 100 percent vested ranging from six months to two years and are fully exercisable when vested. Option exercise prices equal the Corporation's common stock closing price on NASDAQ on the date of grant.  RSAs issued to employees and non-employee directors provide for the issuance of shares of the Corporation's common stock at no cost to the holder and generally vest after three years.  The RSAs vest only if the employee is actively employed by the Corporation on the vesting date and, therefore, any unvested shares are forfeited.  For non-employee directors, the RSA's vest only if the non-employee director remains as an active board member on the vesting date and, therefore, any unvested shares are forfeited. RSAs for employees and non-employee directors retired from the Corporation are either immediately vested at retirement or continue to vest after retirement, depending on the plan under which the shares were granted. Deferred stock units ("DSUs") can be credited to non-employee directors who elect to defer payment of compensation under the Corporation's 2008 Equity Compensation Plan for Non-employee Directors.  DSUs credited are equal to the restricted shares that the non-employee director would have received under the plan.  As of December 31, 2014, the Corporation did not have any outstanding DSUs.
	The Corporation’s 2009 Employee Stock Purchase Plan (“ESPP”) provides eligible employees of the Corporation and its subsidiaries an opportunity to purchase shares of common stock of the Corporation through quarterly offerings financed by payroll deductions. The price of the stock to be paid by the employees shall be equal to 85 percent of the average of the closing price of the Corporation’s common stock on each trading day during the offering period. However, in no event shall such purchase price be less than the lesser of an amount equal to 85 percent of the market price of the Corporation’s stock on the offering date or an amount equal to 85 percent of the market value on the date of purchase. Common stock purchases are made quarterly and are paid through advance payroll deductions up to a calendar year maximum of $25,000.
	Compensation expense related to unvested share-based awards is recorded by recognizing the unamortized grant date fair value of these awards over the remaining service periods of those awards, with no change in historical reported fair values and earnings. Awards are valued at fair value in accordance with provisions of share-based compensation guidance and are recognized on a straight-line basis over the service periods of each award. To complete the exercise of vested stock options, RSA’s and ESPP options, the Corporation generally issues new shares from its authorized but unissued share pool. Share-based compensation for the years ended December 31, 2014, 2013, and 2012 was $2,177,000, $1,773,000, and $1,492,000, respectively, and has been recognized as a component of salaries and benefits expense in the accompanying CONSOLIDATED STATEMENTS OF INCOME.
	The estimated fair value of the stock options granted during 2014, 2013, and 2012 was calculated using a Black-Scholes option pricing model.  The following summarizes the assumptions used in the Black-Scholes model:
		2014			2013			2012
	Risk-free interest rate	2.41	%		1.25	%		1.36	%
	Expected price volatility	45.05	%		45.68	%		46.22	%
	Dividend yield	2.73	%		2.96	%		3.29	%
	Forfeiture rate	5.46	%		4.73	%		4.77	%
	Weighted-average expected life, until exercise	7.74		years	7.27		years	7.2		years
	The Black-Scholes model incorporates assumptions used to value share-based awards. The risk-free rate of interest, for periods equal to the expected life of the option, is based on a U.S. government instrument over a similar contractual term of the equity instrument. Expected price volatility is based on historical volatility of the Corporation’s common stock.  In addition, the Corporation generally uses historical information to determine the dividend yield and weighted-average expected life of the options until exercise. Separate groups of employees that have similar historical exercise behavior with regard to option exercise timing and forfeiture rates are considered separately for valuation and attribution purposes.
	Share-based compensation expense recognized in the CONSOLIDATED STATEMENTS OF INCOME is based on awards ultimately expected to vest and is reduced for estimated forfeitures. Share-based compensation guidance requires forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods, if actual forfeitures differ from those estimates. Pre-vesting forfeitures were estimated to be approximately 5.5 percent for the year ended December 31, 2014, based on historical experience.
	The following table summarizes the components of the Corporation's share-based compensation awards recorded as expense:
		Year Ended				Year Ended				Year Ended
		December 31,				December 31,				December 31,
		2014				2013				2012
	Stock and ESPP Options
	Pre-tax compensation expense	$	237			$	253			$	284
	Income tax benefit	(47		)		(16		)		(23		)
	Stock and ESPP option expense, net of income taxes	$	190			$	237			$	261
	Restricted Stock Awards
	Pre-tax compensation expense	$	1,940			$	1,520			$	1,208
	Income tax benefit	(679		)		(531		)		(428		)
	Restricted stock awards expense, net of income taxes	$	1,261			$	989			$	780
	Total Share-Based Compensation:
	Pre-tax compensation expense	$	2,177			$	1,773			$	1,492
	Income tax benefit	(726		)		(547		)		(451		)
	Total share-based compensation expense, net of income taxes	$	1,451			$	1,226			$	1,041
	As of December 31, 2014, unrecognized compensation expense related to stock options and RSAs totaling $4,000 and $2,618,000, respectively, is expected to be recognized over weighted-average periods of 0.14 years and 1.16 years, respectively.
	Stock option activity under the Corporation's stock option plans, as of December 31, 2014, and changes during the year ended December 31, 2014, were as follows:
		Number of			Weighted-Average				Weighted Average		Aggregate
		Shares			Exercise Price				Remaining Contractual		Intrinsic Value
									Term (in Years)
	Outstanding at January 1, 2014	958,786			$	21.32
	Granted	13,500			$	21.65
	Exercised	(41,249	)		$	12.21
	Canceled	(193,106	)		$	24.42
	Outstanding December 31, 2014	737,931			$	20.99			3.08		2,645,356
	Vested and Expected to Vest at December 31, 2014	737,931			$	20.99			3.08		2,645,356
	Exercisable at December 31, 2014	715,431			$	21.05			2.9		2,563,636
	The weighted-average grant date fair value was $8.13, $5.73 and $3.97 for stock options granted during the years ended December 31, 2014, 2013 and 2012, respectively.
	The aggregate intrinsic value in the table above represents the total pre-tax intrinsic value (the difference between the Corporation's closing stock price on the last trading day of 2014 and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their stock options on December 31, 2014.  The amount of aggregate intrinsic value will change based on the fair market value of the Corporation's common stock.
	The aggregate intrinsic value of stock options exercised during the years ended December 31, 2014 and 2013 was $392,000 and $143,000, respectively. Cash receipts of stock options exercised during 2014 and 2013 were $504,000 and $115,000, respectively.
	The following table summarizes information on unvested RSAs outstanding as of December 31, 2014:
		Number of			Weighted-Average
		Shares			Grant Date Fair Value
	Unvested RSAs at January 1, 2014	429,002			$	12.51
	Granted	98,611			$	20.54
	Forfeited	(9,717	)		$	15.78
	Vested	(132,446	)		$	9.16
	Unvested RSAs at December 31, 2014	385,450			$	15.65
	The grant date fair value of ESPP options was estimated at the beginning of the October 1, 2014, quarterly offering period of approximately $20,000. The ESPP options vested during the three months ending December 31, 2014, leaving no unrecognized compensation expense related to unvested ESPP options at December 31, 2014.

Pension_and_Other_Post_Retirem

Pension and Other Post Retirement Benefit Plans	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Pension and Other Post Retirement Benefit Plans	PENSION AND OTHER POST RETIREMENT BENEFIT PLANS
	The Corporation’s defined-benefit pension plans cover approximately 25 percent of the Corporation’s employees. In 2005, the Board of Directors of the Corporation approved the curtailment of the accumulation of defined benefits for future services provided by certain participants in the First Merchants Corporation Retirement Plan. No additional pension benefits have been earned by any employees who had not attained both the age of 55 and accrued at least 10 years of vesting service as of March 1, 2005. The benefits are based primarily on years of service and employees’ pay near retirement. Contributions are intended to provide not only for benefits attributed to service-to-date, but also for those expected to be earned in the future. The Corporation also maintains post retirement benefit plans that provide health insurance benefits to retirees. The plans allow retirees to be carried under the Corporation’s health insurance plan, generally from ages 55 to 65. The retirees pay 100 percent of the premiums due for their coverage. The table below sets forth the plans’ funded status and amounts recognized in the consolidated balance sheets at December 31, using measurement dates of December 31, 2014 and 2013.
		2014				2013
	Change in Benefit Obligation:
	Benefit obligation at beginning of year	$	62,270			$	69,166
	Service cost	73				131
	Interest cost	3,235				2,670
	Actuarial loss (gain)	12,968				(5,597		)
	Benefits paid	(5,541		)		(4,100		)
	Net transfers in from CFS acquisition	7,645
	Benefit obligation at end of year	$	80,650			$	62,270
	Change in Plan Assets:
	Fair value of plan assets at beginning of year	$	69,871			$	62,865
	Actual return on plan assets	5,232				10,610
	Employer contributions	504				496
	Benefits paid	(5,541		)		(4,100		)
	CFS acquisition	7,073
	End of year	77,139				69,871
	Funded status at end of year	$	(3,511	)		$	7,601
	Assets and Liabilities Recognized in the Balance Sheets:
	Deferred tax asset	$	8,541			$	4,266
	Assets	$	1,329			$	12,383
	Liabilities	$	4,840			$	4,782
	Amounts Recognized in Accumulated Other Comprehensive Income Not Yet Recognized as Components of Net Periodic (Benefit) Cost Consist of:
	Accumulated loss	$	(15,863	)		$	(7,922	)
	Prior service credit	(346		)		(28		)
		$	(16,209	)		$	(7,950	)
	The actuarial loss recognized in 2014 was primarily due to two factors. The first factor was a decrease in the discount rate assumption from 4.80% at December 31, 2013 to 4.00% at December 31, 2014. The second factor contributing to the loss was the Corporation's adoption of the Society of Actuaries new mortality tables.
	Citizens Financial Bank participated in the Pentegra Defined Benefit Plan for Financial Institutions (the "Pentegra Plan”), an industry-wide, tax-qualified defined-benefit pension plan. The Pentegra Plan operated as a multi-employer plan for accounting purposes and as a multiple employer plan under ERISA and the Internal Revenue Code. On September 30, 2013, the Board of Citizens Financial Bank approved a resolution to withdraw as a Participating Employer in the Pentegra Plan. Upon completion of the withdrawal from the Pentegra Plan, the assets and liabilities were merged into the First Merchants Corporation Retirement Plan in early 2014.
	The accumulated benefit obligation for all defined benefit plans was $80,650,000 and $62,263,000 at December 31, 2014 and 2013, respectively.
	Information for pension plans with an accumulated benefit obligation in excess of plan assets is included in the table below.
		December 31, 2014				December 31, 2013
	Projected benefit obligation	$	4,840			$	4,782
	Accumulated benefit obligation	$	4,840			$	4,782
	Fair value of plan assets
	The following table shows the components of net periodic pension costs:
		31-Dec-14				31-Dec-13				31-Dec-12
	Service cost	$	73			$	131			$	161
	Interest cost	3,235				2,670				2,990
	Expected return on plan assets	(4,467		)		(4,265		)		(4,216		)
	Amortization of prior service costs	81				25				25
	Amortization of net loss	478				2,131				2,207
	Net periodic pension (benefit) cost	$	(600	)		$	692			$	1,167
	Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss):
		31-Dec-14				31-Dec-13				31-Dec-12
	Net periodic pension (benefit) cost	$	(600	)		$	692			$	1,167
	Net gain (loss)	(12,203		)		11,942				(1,242		)
	Amortization of loss	478				2,131				2,207
	Amortization of prior service cost	81				25				25
	Total recognized in other comprehensive income (loss)	(11,644		)		14,098				990
	Total recognized in net periodic pension cost and other comprehensive income (loss)	$	(11,044	)		$	13,406			$	(177	)
	The estimated net loss and transition obligation for the defined benefit pension plans that will be amortized from accumulated other comprehensive income into net periodic pension cost over the next fiscal year are:
		December 31, 2014				December 31, 2013				December 31, 2012
	Amortization of net loss	$	(1,770	)		$	(533	)		$	(2,158	)
	Amortization of prior service cost	(64		)		(25		)		(25		)
	Total	$	(1,834	)		$	(558	)		$	(2,183	)
	Significant assumptions include:
		31-Dec-14			31-Dec-13			December 31, 2012
	Weighted-average Assumptions Used to Determine Benefit Obligation:
	Discount rate	4	%		4.8	%		4	%
	Rate of compensation increase for accruing active participants	3	%		3	%		3	%
	Weighted-average Assumptions Used to Determine Cost:
	Discount rate	4.8	%		4	%		4.5	%
	Expected return on plan assets	6	%		7	%		7	%
Rate of compensation increase for accruing active participants	3	%		3	%		4	%
At December 31, 2014 and 2013, the Corporation based its estimate of the expected long-term rate of return on analysis of the historical returns of the plans and current market information available. The plans’ investment strategies are to provide for preservation of capital with an emphasis on long-term growth without undue exposure to risk. The assets of the plans’ are invested in accordance with the plans’ Investment Policy Statement, subject to strict compliance with Employee Retirement Income Security Act of 1974 ("ERISA") and any other applicable statutes.
The plans’ risk management practices include quarterly evaluations of investment managers, including reviews of compliance with investment manager guidelines and restrictions; ability to exceed performance objectives; adherence to the investment philosophy and style; and ability to exceed the performance of other investment managers. The evaluations are reviewed by management with appropriate follow-up and actions taken, as deemed necessary. The Investment Policy Statement generally allows investments in cash and cash equivalents, real estate, fixed income debt securities and equity securities, and specifically prohibits investments in derivatives, options, futures, private placements, short selling, non-marketable securities and purchases of non-investment grade bonds.
At December 31, 2014, the maturities of the plans’ debt securities ranged from 15 days to 9.59 years, with a weighted average maturity of 5.02 years. At December 31, 2013, the maturities of the plans’ debt securities ranged from 2 days to 9.61 years, with a weighted average maturity of 4.63 years.
The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid as of December 31, 2014. The minimum contribution required in 2015 will likely be zero but the Corporation may decide to make a discretionary contribution during the year.
2015	$	4,761
2016	4,757
2017	4,751
2018	4,783
2019	4,997
After 2019	25,125
	$	49,174
Plan assets are re-balanced quarterly. At December 31, 2014 and 2013, plan assets by category are as follows:
	December 31, 2014						December 31, 2013
	Actual			Target			Actual			Target
Cash and cash equivalents	2.6	%		2	%		2.7	%		2	%
Equity securities	58.7			60			62.2			60
Debt securities	36.5			36			33.2			36
Alternative investments	2.2			2			1.9			2
	100	%		100	%		100	%		100	%
The First Merchants Corporation Retirement and Income Savings Plan (the “Savings Plan”), a Section 401(k) qualified defined contribution plan, was amended on March 1, 2005 to provide enhanced retirement benefits, including employer and matching contributions, for eligible employees of the Corporation and its subsidiaries. The Corporation matches employees’ contributions primarily at the rate of 50 percent for the first 6 percent of base salary contributed by participants.
Beginning in 2005, employees who have completed 1000 hours of service and are an active employee on the last day of the year receive an additional retirement contribution after year-end. Employees hired after January 1, 2010 do not participate in the additional retirement contribution. Effective January 1, 2013, the additional retirement contribution was fixed at 2 percent. Full vesting occurs after five years of service. The Corporation’s expense for the Savings Plan, including the additional retirement contribution, was $3,396,000, $3,138,000 and $2,914,000 for 2014, 2013 and 2012, respectively.
The Corporation maintains post retirement benefit plans that provide health insurance benefits to retirees. The plans allow retirees to be carried under the Corporation’s health insurance plan, generally from ages 55 to 65. The retirees pay 100 percent of the premiums due for their coverage. The obligations payable under the plans totaled $1,811,000 and $1,534,000 at December 31, 2014 and 2013, respectively. Post retirement plan expense totaled $97,000, $519,000 and $477,000 for the years ending December 31, 2014, 2013 and 2012, respectively.
Pension Plan Assets
Following is a description of the valuation methodologies used for pension plan assets measured at fair value on a recurring basis, as well as the general classification of pension plan assets pursuant to the valuation hierarchy.
Where quoted market prices are available in an active market, plan assets are classified within Level 1 of the valuation hierarchy.  Level 1 plan assets total $57,413,000 and include cash and cash equivalents, common stocks, mutual funds and corporate bonds and notes.  If quoted market prices are not available, then fair values are estimated by using pricing models, quoted prices of plan assets with similar characteristics or discounted cash flows.  Level 2 plan assets total $19,726,000 and include governmental agencies, taxable municipals, common collective trust investments (which are classified below as Party-in-Interest investments -- common bond fund and common equity fund) and certificates of deposit.  In certain cases where Level 1 or Level 2 inputs are not available, plan assets are classified within Level 3 of the hierarchy.  There are no assets classified within Level 3 of the hierarchy at December 31, 2014 and 2013.
					Fair Value Measurements Using
					Quoted Prices in				Significant Other Observable Inputs			Significant
					Active Markets for							Unobservable
					Identical Assets							Inputs
December 31, 2014	Fair Value				(Level 1)				(Level 2)			(Level 3)
Cash & Cash Equivalents	$	2,032			$	2,032
Corporate Bonds and Notes	9,384				9,384
Government Agency and Municipal Bonds and Notes	8,252								$	8,252
Certificates of Deposit	1,001								1,001
Party-in-Interest Investments
Common Stock	1,376				1,376
Common Bond Fund	4,615								4,615
Common Equity Fund	5,858								5,858
Mutual Funds
Taxable Bond	4,987				4,987
Large Cap Equity	21,185				21,185
Mid Cap Equity	9,434				9,434
Small Cap Equity	3,872				3,872
International Equity	3,474				3,474
Specialty Alternative Equity	1,669				1,669
	$	77,139			$	57,413			$	19,726		$	—
					Fair Value Measurements Using
					Quoted Prices in				Significant Other Observable Inputs			Significant
					Active Markets for							Unobservable
					Identical Assets							Inputs
December 31, 2013	Fair Value				(Level 1)				(Level 2)			(Level 3)
Cash & Cash Equivalents	$	1,864			$	1,864
Corporate Bonds and Notes	6,076				6,076
Government Agency and Municipal Bonds and Notes	8,263								$	8,263
Certificates of Deposit	607								607
Party-in-Interest Investments
Common Stock	1,375				1,375
Common Bond Fund	5,318								5,318
Common Equity Fund	4,507								4,507
Mutual Funds
Taxable Bond	3,901				3,901
Large Cap Equity	20,617				20,617
Mid Cap Equity	8,721				8,721
Small Cap Equity	3,584				3,584
International Equity	3,727				3,727
Specialty Alternative Equity	1,311				1,311
	$	69,871			$	51,176			$	18,695		$	—

Income_Tax

Income Tax	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax	INCOME TAX
	The reconciliation between the statutory and actual income tax expense (benefit) is summarized in the following table for the years indicated:
		2014			2013			2012
	Income Tax Expense for the Year Ended December 31:
	Currently Payable:
	Federal	$	(1,661	)	$	738		$	(23	)
	State
	Deferred:
	Federal	22,541			13,939			15,890
	State	510
	Total Income Tax Expense	$	21,390		$	14,677		$	15,867
	Reconciliation of Federal Statutory to Actual Tax Expense:
	Federal Statutory Income Tax at 35%	$	28,543		$	20,722		$	21,347
	Tax-exempt Interest Income	(5,148		)	(3,923		)	(3,716		)
	Stock Compensation	36			50			76
	Earnings on Life Insurance	(1,271		)	(905		)	(1,187		)
	Tax Credits	(911		)	(857		)	(73		)
	Other	141			(410		)	(580		)
	Actual Tax Expense	$	21,390		$	14,677		$	15,867
	Tax expense applicable to security gains and losses, including unrealized losses relating to other-than-temporary impairment charges, for the years ended December 31, 2014, 2013 and 2012, was $760,000, $157,000 and $759,000, respectively.
	The Corporation or one of its subsidiaries files income tax returns in the U.S. federal jurisdiction and various state jurisdictions.  With a few exceptions, the Corporation is no longer subject to U.S. federal, state and local or non-U.S. income tax examinations by tax authorities for years before 2011.
	The tax effects of temporary differences related to deferred taxes shown on the balance sheets were:
		2014			2013
	Deferred Tax Asset at December 31:
	Assets:
	Differences in Accounting for Loan Losses	$	26,665		$	28,064
	Differences in Accounting for Loan Fees	747			736
	Differences in Accounting for Loans and Securities	9,910			13,579
	Deferred Compensation	5,234			5,479
	Difference in Accounting for Pensions and Other Employee Benefits	1,084
	Federal & State Income Tax Loss Carryforward and Credits	23,977			24,981
	Net Unrealized Loss on Securities Available for Sale				151
	Other	8,535			12,828
	Total Assets	76,152			85,818
	Liabilities:
	Differences in Depreciation Methods	8,220			8,008
	Difference in Accounting for Pensions and Other Employee Benefits				1,096
	State Income Tax	591			354
	Net Unrealized Gain on Securities Available for Sale	7,591
	Gain on FDIC Modified Whole Bank Transaction	1,694			2,147
	Other	1,096			1,257
	Total Liabilities	19,192			12,862
	Net Deferred Tax Asset Before Valuation Allowance	56,960			72,956
	Valuation allowance:
	Beginning Balance	(17,171		)	(13,859		)
	Decrease/(Increase) During the Year	(397		)	(3,312		)
	Ending Balance	(17,568		)	(17,171		)
	Net Deferred Tax Asset	$	39,392		$	55,785
	The $16,393,000 decrease in the Corporation’s net deferred tax asset was due to a combination of a decrease in deferred tax assets and an increase in deferred tax liabilities. The largest deferred tax asset decreases were associated with accounting for loans, other than temporary impairment on securities, and other real estate owned in the amounts of $3,669,000, $3,261,000 and $1,988,000, respectively. Partially offsetting these deferred tax asset decreases was the $2,180,000 net change in the shift of the accounting for pensions and other employee benefits from a deferred tax liability to a deferred tax asset. Finally, the largest deferred tax liability increase of $7,742,000 resulted from the accounting for unrealized gains on available for sale securities.
	The Corporation has recorded a valuation allowance of $17,568,000 related to deferred state taxes as it does not anticipate having future state taxable income sufficient to fully utilize the deferred state tax asset.  This is primarily due to the Corporation’s current tax structure as discussed in the “INCOME TAXES” section of Management’s Discussion and Analysis of Financial Condition and Results of Operations included as item 7 of this Annual Report on Form 10-K.
	As of December 31, 2014, the Corporation had approximately $143,467,000 of state tax loss carryforward available to offset future state taxes.  This state loss carryforward has a valuation allowance of approximately $142,358,000.
	The Corporation has approximately $13,393,000 of additional paid-in capital that is considered restricted resulting from the CFS acquisition. CFS qualified as a bank under provisions of the Internal Revenue Code which permitted it to deduct from taxable income an allowance for bad debts which differed from the provision for losses charged to income. No provision for income taxes had been provided. If in the future this portion of additional paid-in capital is distributed, or the Corporation no longer qualifies as a bank for income tax purposes, income taxes may be imposed at the then applicable tax rates. The unrecorded deferred tax liability at December 31, 2014, would have been approximately $4,688,000.

Net_Income_Per_Share

Net Income Per Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Net Income Per Share	NET INCOME PER SHARE
	Basic net income per share is computed by dividing net income by the weighted-average shares outstanding during the reporting period. Diluted net income per share is computed by dividing net income by the combination of all dilutive common share equivalents, comprised of shares issuable under the Corporation’s share-based compensation plans, and the weighted-average shares outstanding during the reporting period.
	Dilutive common share equivalents include the dilutive effect of in-the-money share-based awards, which are calculated based on the average share price for each period using the treasury stock method. Under the treasury stock method, the exercise price of share-based awards, the amount of compensation expense, if any, for future service that the Corporation has not yet recognized, and the amount of estimated tax benefits that would be recorded in additional paid-in capital when share-based awards are exercised, are assumed to be used to repurchase common stock in the current period.
	The following table reconciles basic and diluted net income per share for the years indicated:
		2014					2013						2012
				Weighted-Average Shares						Weighted-Average Shares						Weighted-Average Shares
	Basic net income per share:	$	60,162				$	44,530					$	45,122
	Preferred stock dividends						(2,380		)				(4,539		)
	Net income available to common stockholders	60,162		36,266,356	$	1.66	42,150			29,731,420	$	1.42	40,583			28,632,915	$	1.42
	Effect of dilutive stock options and warrants			288,253						276,960						213,769
	Diluted net income per share:
	Net income available to common stockholders	$	60,162	36,554,609	$	1.65	$	42,150		30,008,380	$	1.41	$	40,583		28,846,684	$	1.41
	Options to purchase 543,514, 800,674, and 820,706 shares of common stock with weighted average exercise prices of $20.99, $21.32, and $21.58 at December 31, 2014, 2013 and 2012 respectively, were excluded from the computation of diluted net income per share because the options exercise price was greater than the average market price of the common stock.

Quarterly_Results_of_Operation

Quarterly Results of Operations (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Results of Operations (Unaudited)	QUARTERLY RESULTS OF OPERATIONS (UNAUDITED)
	The following table sets forth certain quarterly results for the years ended December 31, 2014 and 2013:
		2014								2013
		First		Second		Third		Fourth		First			Second			Third			Fourth
	Interest income	$	51,009	$	51,527	$	53,290	$	53,053	$	43,738		$	40,653		$	40,736		$	45,707
	Interest expense	5,117		5,408		5,424		5,893		4,280			4,003			3,714			4,572
	Net interest income	45,892		46,119		47,866		47,160		39,458			36,650			37,022			41,135
	Provision for loan losses					1,600		960		2,102			1,997			1,533			1,016
	Net interest income after provision for loan losses	45,892		46,119		46,266		46,200		37,356			34,653			35,489			40,119
	Non-interest income	15,186		15,933		18,294		16,254		13,877			14,059			11,800			15,073
	Non-interest expense	43,089		41,250		42,576		41,677		34,700			33,742			34,219			40,558
	Income before income tax expense	17,989		20,802		21,984		20,777		16,533			14,970			13,070			14,634
	Income tax expense	4,369		5,642		5,862		5,517		4,668			4,155			2,667			3,187
	Net income	13,620		15,160		16,122		15,260		11,865			10,815			10,403			11,447
	Preferred stock dividends									(857		)	(852		)	(430		)	(241		)
	Net income available to common stockholders	$	13,620	$	15,160	$	16,122	$	15,260	$	11,008		$	9,963		$	9,973		$	11,206
	Basic EPS	$	0.38	$	0.42	$	0.45	$	0.41	$	0.38		$	0.35		$	0.35		$	0.34
	Diluted EPS	$	0.38	$	0.41	$	0.45	$	0.41	$	0.38		$	0.34		$	0.35		$	0.34
	Average Shares Outstanding:
	Basic	35,956,436		36,026,763		36,054,867		37,018,014		28,716,987			28,783,407			28,806,809			32,597,145
	Diluted	36,260,624		36,294,149		36,328,981		37,323,276		28,971,238			29,023,513			29,081,472			32,912,605

Condensed_Financial_Informatio

Condensed Financial Information (parent company only)	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Financial Information (parent company only)	CONDENSED FINANCIAL INFORMATION (parent company only)
	Presented below is condensed financial information as to financial position, results of operations, and cash flows of the Corporation.
	Condensed Balance Sheets
		31-Dec-14			31-Dec-13
	Assets
	Cash	$	36,044		$	13,228
	Investment in subsidiaries	820,123			745,818
	Goodwill	448			448
	Other assets	6,281			8,695
	Total assets	$	862,896		$	768,189
	Liabilities
	Borrowings	$	126,702		$	126,702
	Other liabilities	9,367			6,564
	Total liabilities	136,069			133,266
	Stockholders' equity	726,827			634,923
	Total liabilities and stockholders' equity	$	862,896		$	768,189
	Condensed Statements of Income and Comprehensive Income
		December 31, 2014			December 31, 2013			December 31, 2012
	Income
	Dividends from subsidiaries	$	53,231		$	63,732		$	30,096
	Other income	538			45			85
	Total income	53,769			63,777			30,181
	Expenses
	Interest expense	6,616			3,531			4,655
	Salaries and employee benefits	3,128			3,284			3,194
	Net occupancy and equipment expenses	442			258			312
	Telephone expenses	27			42			30
	Postage and courier expenses							1
	Other expenses	1,972			2,617			1,502
	Total expenses	12,185			9,732			9,694
	Income before income tax benefit and equity in undistributed income of subsidiaries	41,584			54,045			20,487
	Income tax benefit	3,999			3,153			3,316
	Income before equity in undistributed income of subsidiaries	45,583			57,198			23,803
	Equity in undistributed (distributions in excess of) income of subsidiaries	14,579			(12,668		)	21,319
	Net income	60,162			44,530			45,122
	Preferred stock dividends and discount accretion				(2,380		)	(4,539		)
	Net income available to common stockholders	$	60,162		$	42,150		$	40,583
	Net income	$	60,162		$	44,530		$	45,122
	Other comprehensive income (loss)	4,780			(911		)	(1,897		)
	Comprehensive income	$	64,942		$	43,619		$	43,225
	Condensed Statement of Cash Flows
		Year Ended December 31,
		2014			2013			2012
	Cash Flow From Operating Activities:
	Net income	$	60,162		$	44,530		$	45,122
	Adjustments to Reconcile Net Income to Net Cash:
	Share-based compensation	887			778			632
	Distributions in excess of (equity in undistributed) income of subsidiaries	(14,579		)	12,668			(21,319		)
	Net Change in:
	Other assets	2,425			(1,354		)	1,902
	Other liabilities	1,466			(8,438		)	1,122
	Investment in subsidiaries - operating activities	(4,517		)	12,991			(1,755		)
	Net cash provided by operating activities	$	45,844		$	61,175		$	25,704
	Cash Flow From Investing Activities:
	Investment in subsidiaries							$	(126	)
	Net cash paid in acquisition	$	(12,832	)
	Other				$	240
	Net cash provided (used) in investing activities	$	(12,832	)	$	240		$	(126	)
	Cash Flow From Financing Activities:
	Cash dividends	$	(10,694	)	$	(7,992	)	$	(7,442	)
	Repayment of borrowings				(55,000		)	(4,124		)
	Proceeds from issuance of long-term debt				70,000
	Preferred stock redemption under small business lending fund				(90,783		)
	Stock issued under employee benefit plans	478			479			449
Stock issued under dividend reinvestment and stock purchase plan	523			325			202
Stock options exercised	564			115			78
Stock redeemed	(1,067		)	(491		)	(235		)
Net cash used by financing activities	$	(10,196	)	$	(83,347	)	$	(11,072	)
Net change in cash	22,816			(21,932		)	14,506
Cash, beginning of the year	13,228			35,160			20,654
Cash, end of year	$	36,044		$	13,228		$	35,160

Accounting_Matters

Accounting Matters	12 Months Ended
	Dec. 31, 2014
Accounting Changes and Error Corrections [Abstract]
Accounting Matters	ACCOUNTING MATTERS
	FASB Accounting Standards Update No. 2015-01, Income Statement -Extraordinary and Unusual Items (Subtopic 225-20): Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items
	The FASB has issued Accounting Standards Update (ASU) No. 2015-01, Income Statement - Extraordinary and Unusual Items (Subtopic 225-20): Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items. The FASB issued this ASU as part of its initiative to reduce complexity in accounting standards.
	This ASU eliminates from U.S. GAAP the concept of extraordinary items. Subtopic 225-20, Income Statement - Extraordinary and Unusual Items, required that an entity separately classify, present, and disclose extraordinary events and transactions. Presently, an event or transaction is presumed to be an ordinary and usual activity of the reporting entity unless evidence clearly supports its classification as an extraordinary item.
	If an event or transaction meets the criteria for extraordinary classification, an entity is required to segregate the extraordinary item from the results of ordinary operations and show the item separately in the income statement, net of tax, after income from continuing operations. The entity also is required to disclose applicable income taxes and either present or disclose earnings-per-share data applicable to the extraordinary item.
	The amendments in this ASU are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. A reporting entity may apply the amendments prospectively. A reporting entity also may apply the amendments retrospectively to all prior periods presented in the financial statements. Early adoption is permitted provided that the guidance is applied from the beginning of the fiscal year of adoption. Adoption of the ASU is not expected to have a significant effect on the Corporation’s consolidated financial statements.
	FASB ASU No. 2014-17 Business Combinations (Topic 805): Pushdown Accounting
	The amendments in this Update provide an acquired entity with an option to apply pushdown accounting in its separate financial statements upon occurrence of an event in which an acquirer obtains control of the acquired entity.
	An acquired entity may elect the option to apply pushdown accounting in the reporting period in which the change-in-control event occurs. An acquired entity should determine whether to elect to apply pushdown accounting for each individual change-in-control event in which an acquirer obtains control of the acquired entity. If pushdown accounting is not applied in the reporting period in which the change-in-control event occurs, an acquired entity will have the option to elect to apply pushdown accounting in a subsequent reporting period to the acquired entity’s most recent change-in-control event. An election to apply pushdown accounting in a reporting period after the reporting period in which the change-in-control event occurred should be considered a change in accounting principle in accordance with Topic 250, Accounting Changes and Error Corrections. If pushdown accounting is applied to an individual change-in-control event, that election is irrevocable.
	If an acquired entity elects the option to apply pushdown accounting in its separate financial statements, it should disclose information in the current reporting period that enables users of financial statements to evaluate the effect of pushdown accounting.
	The amendments in this Update are effective on November 18, 2014. After the effective date, an acquired entity can make an election to apply the guidance to future change-in-control events or to its most recent change-in-control event. However, if the financial statements for the period in which the most recent change-in-control event occurred already have been issued or made available to be issued, the application of this guidance would be a change in accounting principle. Adoption of the ASU is not expected to have a significant effect on the Corporation’s consolidated financial statements.
	FASB ASU 2014-15, Presentation of Financial Statements-Going Concern (Subtopic 204-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern
	In August 2014, FASB, issued ASU 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. The update provides U.S. GAAP guidance on management’s responsibility in evaluating whether there is substantial doubt about a company’s ability to continue as a going concern and about related footnote disclosures. For each reporting period, management will be required to evaluate whether there are conditions or events that raise substantial doubt about a company’s ability to continue as a going concern within one year from the date the financial statements are issued. The amendments in this update are effective for annual reporting periods ending after December 15, 2016, and for annual and interim periods thereafter. Early adoption is permitted. Adoption of the ASU is not expected to have a significant effect on the Corporation’s consolidated financial statements.
	FASB ASU 2014-14, Receivables-Troubled Debt Restructuring by Creditors (Subtopic 310-40): Classification of Certain Government-Guaranteed Mortgage Loans upon Foreclosure
	In August 2014, FASB, issued ASU 2014-14, Classification of Certain Government-Guaranteed Mortgage Loans upon Foreclosure. The objective of this update is to reduce diversity in practice by addressing the classification of foreclosed mortgage loans that are fully or partially guaranteed under government programs. Currently, some creditors reclassify those loans to real estate as with other foreclosed loans that do not have guarantees; others reclassify the loans to other receivables. The amendments affect creditors that hold government-guaranteed mortgage loans, including those guaranteed by the FHA and the VA. The amendments in this update are effective for annual reporting periods ending after December 15, 2015 and interim periods beginning after December 15, 2015. An entity should adopt the amendments in this update using either a prospective transition method or a modified retrospective transition method. For prospective transition, an entity should apply the amendments in this update to foreclosures that occur after the date of adoption. For the modified retrospective transition, an entity should apply the amendments in the update by means of a cumulative-effect adjustment (through a reclassification to a separate other receivable) as of the beginning of the annual period of adoption. Prior periods should not be adjusted. However, a reporting entity must apply the same method of transition as elected under ASU No. 2014-04. Early adoption, including adoption in an interim period, is permitted if the entity already has adopted update 2014-04. Adoption of the ASU is not expected to have a significant effect on the Corporation’s consolidated financial statements.
	FASB ASU 2014-12, Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved After the Requisite Service Period
	A consensus of the FASB Emerging Issues Task Force. The amendments in this update clarify that entities should treat performance targets that can be met after the requisite service period of a share-based payment award as performance conditions that affect vesting. Therefore, an entity would not record compensation expense (measured as of the grant date without taking into account the effect of the performance target) related to an award for which transfer to the employee is contingent on the entity’s satisfaction of a performance target until it becomes probable that the performance target will be met. The ASU does not contain any new disclosure requirements. The ASU is effective for interim and annual reporting periods beginning after December 15, 2015. Early adoption is permitted. In addition, entities will have the option of applying the guidance either prospectively (i.e., only to awards granted or modified on or after the effective date) or retrospectively. Retrospective application would only apply to awards with performance targets outstanding at or after the beginning of the first annual period presented (i.e., the earliest presented comparative period). Adoption of the ASU is not expected to have a significant effect on the Corporation’s consolidated financial statements.
	FASB ASU 2014-11, Transfers and Servicing: Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures
	The amendments in this update require entities to account for repurchase-to-maturity transactions as secured borrowings (rather than as sales with forward repurchase agreements), eliminates accounting guidance on linking repurchase financing transactions, and expands disclosure requirements related to certain transfers of financial assets that are accounted for as sales and certain transfers, such as repos, securities lending transactions, and repurchase-to-maturity transactions, accounted for as secured borrowings. The amendments in ASU 2014-11 are effective for annual periods beginning after December 15, 2014. The amendments must present changes in accounting for transactions outstanding on the effective date as a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. Early application is prohibited. Adoption of the ASU is not expected to have a significant effect on the Corporation’s consolidated financial statements.
	FASB ASU 2014-09, Revenue from Contracts with Customers
	The amendments in this update supersede virtually all existing GAAP revenue recognition guidance, including most industry-specific revenue recognition guidance. ASU 2014-09 creates a single, principle-based revenue recognition framework and will require entities to apply significantly more judgment and expanded disclosures surrounding revenue recognition. The core principle requires an entity to recognize revenue in a manner that depicts the transfer of goods or services to customers at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 applies to contracts with customers to provide goods and services, with certain exclusions such as lease contracts, financing arrangements, and financial instruments. The amendments in ASU 2014-09 are effective for annual reporting periods beginning after December 15, 2017. Early adoption is permitted for annual reporting periods beginning after December 15, 2016. The Corporation is evaluating the effect of this ASU on its consolidated financial statements.
	Accounting Standards Update (ASU) 2014-04, Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure
	In January 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-04, Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure, to reduce diversity by clarifying when a creditor should be considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan such that the loan receivable should be derecognized and the real estate property recognized. The ASU is effective for fiscal years, and interim periods within those years, beginning after December 15, 2014. Adoption of the ASU is not expected to have a significant effect on the Corporation’s consolidated financial statements.
	ASU 2014-01, Accounting for Investments in Qualified Affordable Housing Projects
	In January 2014, the FASB issued ASU 2014-01, Accounting for Investments in Qualified Affordable Housing Projects, to permit entities to make an accounting policy election to account for their investments in qualified affordable housing projects using the proportional amortization method if certain conditions are met.  The ASU modifies the conditions that an entity must meet to be eligible to use a method other than the equity or cost methods to account for qualified affordable housing project investments. The ASU is effective for fiscal years, and interim periods within those years, beginning after December 15, 2014. Adoption of the ASU is not expected to have a significant effect on the Corporation’s consolidated financial statements.

General_Litigation

General Litigation	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
General Litigation	GENERAL LITIGATION
	The Corporation is subject to claims and lawsuits that arise primarily in the ordinary course of business. It is the opinion of management that the disposition or ultimate resolution of such claims and lawsuits will not have a material adverse effect on the consolidated financial position, results of operations and cash flow of the Corporation.

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS
	On January 5, 2015, First Merchants Corporation, an Indiana corporation (“First Merchants”), and C Financial Corporation, an Ohio corporation (“C Financial”), entered into an Agreement and Plan of Reorganization and Merger (the “Merger Agreement”), pursuant to which, C Financial will, subject to the terms and conditions of the Merger Agreement, merge with and into First Merchants (the “Merger,”) whereupon the separate corporate existence of C Financial will cease and First Merchants will survive. Immediately following the Merger, Cooper State Bank, an Ohio state bank and wholly-owned subsidiary of C Financial, will be merged with and into First Merchants Bank, National Association, a national bank and wholly-owned subsidiary of First Merchants, with First Merchants Bank, National Association continuing as the surviving bank. The Merger Agreement has been approved by the Boards of Directors of each of First Merchants and C Financial, but the consummation of the Merger is conditioned upon the approval of the C Financial shareholders and certain regulatory authorities as well as satisfaction of customary closing conditions. The Merger Agreement provides that upon the effective date of the Merger (the “Effective Date”), the shareholders of C Financial shall be entitled to receive an aggregate of $14,500,000 in cash in exchange for all of the outstanding shares of C Financial common stock, $1.00 par value. The amount each shareholder will receive will be equal to $14,500,000 multiplied by a fraction, the numerator of which is the number of shares of C Financial Common Stock held by such shareholder and the denominator of which is the number of shares of C Financial Common Stock outstanding on the Effective Date. Any shareholders who dissent from the Merger in accordance with Ohio Revised Code Sections 1701.84 and 1701.85, as amended, will only receive payment through the dissenters’ rights proceedings. Subject to C Financial common shareholders’ approval of the Merger Agreement, regulatory approvals and other customary closing conditions, the parties anticipate completing the Merger in the second quarter of 2015.

Policies

(Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Accounting	The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Consolidation	CONSOLIDATION of the Corporation's financial statements include the accounts of the Corporation and all its subsidiaries, after elimination of all material intercompany transactions.
Business Combinations	BUSINESS COMBINATIONS are accounted for under the acquisition method of accounting. Under the acquisition method, assets and liabilities of the business acquired are recorded at their estimated fair values as of the date of acquisition with any excess of the cost of the acquisition over the fair value of the net tangible and intangible assets acquired recorded as goodwill. Results of operations of the acquired business are included in the income statement from the date of acquisition.
Available For Sale Securities	AVAILABLE FOR SALE SECURITIES are recorded at fair value on a recurring basis with the unrealized gains and losses, net of applicable income taxes, recorded in other comprehensive income. Realized gains and losses are recorded in earnings and the prior fair value adjustments are reclassified within stockholders' equity. Gains and losses on sales of securities are determined on the specific-identification method. Amortization of premiums and accretion of discounts are recorded as interest income from securities.
	Available for sale and held to maturity securities are evaluated for other-than-temporary impairment (“OTTI”) at least on a quarterly basis, and more frequently when economic or market conditions warrant such an evaluation. The investment securities portfolio is evaluated for OTTI by segregating the portfolio into two general segments and applying the appropriate OTTI model. Investment securities are generally evaluated for OTTI under ASC 320. However, certain purchased beneficial interest, including certain non-agency government-sponsored mortgage-backed securities, asset-backed securities and collateralized debt obligations are evaluated using the model outlined in ASC 325-10.
	In determining OTTI under ASC 320, management considers many factors, including: (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near term prospects of the issuer, (3) whether the market decline was affected by macroeconomic conditions, and (4) whether the Corporation has the intent to sell the debt security or more likely than not will be required to sell the debt security before its anticipated recovery. The assessment of whether a decline exists that is other-than-temporary, involves a high degree of subjectivity and judgment and is based on the information available to management at a point in time.
	When the Corporation does not intend to sell a debt security, and it is more likely than not, the Corporation will not have to sell the security before recovery of its cost basis, it recognizes the credit component of an other-than-temporary impairment of a debt security in earnings and the remaining portion in other comprehensive income.  The amount of the total OTTI related to the credit loss is determined based on the present value of cash flows expected to be collected and is recognized in earnings. The amount of the total OTTI related to other factors has been recognized in other comprehensive income, net of applicable income taxes. The previous amortized cost basis less the OTTI recognized in earnings becomes the new amortized cost basis of the investment.
	If the intent is to sell or it is more likely than not that the Corporation will be required to sell the security before recovery of its amortized cost basis, less any recognized credit loss, the OTTI is recognized in earnings equal to the entire difference between the investment’s amortized cost basis, less any recognized credit loss, and its fair value at the balance sheet date.
Held To Maturity Securities	HELD TO MATURITY SECURITIES are classified as held to maturity when the Corporation has the positive intent and ability to hold the securities to maturity. Securities held to maturity are carried at amortized cost.  For held to maturity debt securities, the amount of an OTTI recorded in other comprehensive income for the noncredit portion of a previous other-than-temporary impairment is amortized prospectively over the remaining life of the security on the basis of the timing of future estimated cash flows of the security.
Loans Held For Sale	LOANS HELD FOR SALE are carried at the principal amount outstanding. The carrying amount approximates fair value due to the short duration between origination and the date of sale.
Loans	LOANS held in the Corporation’s portfolio are carried at the principal amount outstanding, net of unearned income. Certain non-accrual and substantially delinquent loans may be considered to be impaired. A loan is impaired when, based on current information or events, it is probable that the Bank will be unable to collect all amounts due (principal and interest) according to the contractual terms of the loan agreement. In applying the provisions of ASC 310, the Corporation considers its investment in one-to-four family residential loans and consumer installment loans to be homogeneous and therefore excluded from separate identification for evaluation of impairment. Interest income is accrued on the principal balances of loans, except for installment loans with add-on interest, for which a method that approximates the level yield method is used. The accrual of interest on impaired loans is discontinued when, in management’s opinion, the borrower may be unable to meet payments as they become due. When interest accrual is discontinued, all unpaid accrued interest is reversed against earnings when considered uncollectable. Interest income accrued in the prior year, if any, is charged to the allowance for loan losses. Interest income is subsequently recognized only to the extent cash payments are received and the loan is returned to accruing status. Certain loan fees and direct costs are being deferred and amortized as an adjustment of yield on the loans.
	Impaired loans are carried at the present value of estimated future cash flows using the loan’s existing rate, or the fair value of collateral if the loan is collateral dependent. A portion of the allowance for loan losses is allocated to impaired loans if the value of such loans is deemed to be less than the unpaid balance. If these allocations cause the allowance for loan losses to increase, such increase is reported as a component of the provision for loan losses. Loan losses are charged against the allowance when management believes the uncollectability of the loan is confirmed. The valuation would be considered Level 3, consisting of appraisals of underlying collateral and discounted cash flow analysis.
	Loan commitments and letters-of-credit generally have short-term, variable-rate features and contain clauses which limit the Bank’s exposure to changes in customer credit quality. Accordingly, their carrying values, which are immaterial at the respective balance sheet dates, are reasonable estimates of fair value.
Loans Acquired in Business Combinations	LOANS ACQUIRED IN BUSINESS COMBINATIONS with evidence of credit deterioration since origination and for which it is probable that all contractually required payments will not be collected are considered to be credit impaired. Evidence of credit quality deterioration as of purchase dates may include information such as past-due and nonaccrual status, borrower credit scores and recent loan to value percentages. Acquired credit-impaired loans are accounted for under the accounting guidance for loans and debt securities acquired with deteriorated credit quality (ASC 310-30). These loans are initially measured at fair value based upon expected cash flows without anticipation of prepayments and includes estimated future credit losses expected to be incurred over the life of the loans. As a result, related discounts are recognized subsequently through accretion based on the expected cash flows of the acquired loans. For purposes of applying ASC 310-30, loans acquired in business combinations are aggregated into pools of loans with common risk characteristics for the initial fair value measurement. Accordingly, allowances for credit losses related to these loans are not carried over and recorded at the acquisition date.
	The expected cash flows of the acquired loans in excess of the fair values recorded is referred to as the accretable yield and is recognized in interest income over the remaining estimated lives of the loans. The Corporation will continually evaluate the fair value of the loans including cash flows expected to be collected.
Allowance for Loan Losses	ALLOWANCE FOR LOAN LOSSES is maintained to absorb losses inherent in the loan portfolio and is based on ongoing, quarterly assessments of the probable losses inherent in the loan portfolio. The allowance is increased by the provision for loan losses, which is charged against current operating results. Loan losses are charged against the allowance when management believes the uncollectability of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance. The Corporation’s strategy for credit risk management includes conservative credit policies and underwriting criteria for all loans, as well as an overall credit limit for each customer significantly below legal lending limits. The strategy also emphasizes diversification on a regional geographic, industry and customer level, regular credit quality reviews and management reviews of large credit exposures and loans experiencing deterioration of credit quality.
	The Corporation’s methodology for assessing the appropriateness of the allowance consists of three key elements – the determination of the appropriate reserves for specifically identified loans, probable losses estimated from historical loss rates, and probable losses resulting from economic, environmental, qualitative or other deterioration above and beyond what is reflected in the first two components of the allowance.
	Larger commercial loans that exhibit probable or observed credit weaknesses are subject to individual review. Where appropriate, reserves are allocated to individual loans based on management’s estimate of the borrower’s ability to repay the loan given the availability of collateral, other sources of cash flow and legal options available to the Corporation. Included in the review of individual loans are those that are impaired as provided in ASC 310. Any allowances for impaired loans are measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate or fair value of the underlying collateral. The Corporation evaluates the collectability of both principal and interest when assessing the need for a loss accrual. Historical loss rates are applied to other commercial loans not subject to specific reserve allocations.
	The historical allocation for commercial loans graded pass are established by loan segments using loss rates based on the Corporation’s migration analysis. This migration analysis shows the loss rates for each segment of loans based on the loan grades at the beginning of the twelve month period. This loss rate is then applied to the current portfolio of loans in each respective loan segment.
	Homogenous loans, such as consumer installment and residential mortgage loans, are not individually risk graded. Reserves are established for each segment of loans using loss rates based on charge offs for the same period as the migration analysis used for commercial loans.
	Historical loss allocations for commercial and consumer loans may be adjusted for significant factors that, in management’s judgment, reflect the impact of any current conditions on loss recognition. Factors which management considers in the analysis include the effects of the national and local economies, trends in loan growth and charge-off rates, changes in mix, concentration of loans in specific industries, asset quality trends (delinquencies, charge offs and non-accrual loans), risk management and loan administration, changes in the internal lending policies and credit standards, examination results from bank regulatory agencies and the Corporation’s internal loan review.
Pension	PENSION benefits are provided to the Corporation’s employees. Its accounting policies related to pensions and other post retirement benefits reflect the guidance in ASC 715, Compensation – Retirement Benefits. The Corporation does not consolidate the assets and liabilities associated with the pension plan. Instead, the Corporation recognizes the funded status of the plan in the consolidated balance sheets. The measurement of the funded status and the annual pension expense involves actuarial and economic assumptions. Various statistical and other factors, which attempt to anticipate future events, are used in calculating the expense and liabilities related to the plans. Key factors include assumptions on the expected rates of return on plan assets, discount rates, expected rates of salary increases and health care costs and trends. The Corporation considers market conditions, including changes in investment returns and interest rates in making these assumptions. The primary assumptions used in determining the Corporation’s pension and post retirement benefit obligations and related expenses are presented in Note 21. PENSION AND OTHER POST RETIREMENT BENEFIT PLANS, in the Notes to Consolidated Financial Statements included as Item 8 of this Annual Report on Form 10-K.
Premises and Equipment	PREMISES AND EQUIPMENT is carried at cost net of accumulated depreciation. Depreciation is computed using the straight-line and declining balance methods based on the estimated useful lives of the assets ranging from three to forty years. Maintenance and repairs are expensed as incurred, while major additions and improvements, which extend the useful life, are capitalized. Gains and losses on dispositions are included in current operations.
Federal Reserve and Federal Home Loan Bank Stock	FEDERAL RESERVE AND FEDERAL HOME LOAN BANK STOCK are required investments for institutions that are members of the Federal Reserve Bank (“FRB”) and Federal Home Loan Bank systems. The required investment in the common stock is based on a predetermined formula based on the level of borrowings and other factors. These investments are carried at cost, classified as a restricted security and periodically evaluated for impairment based on ultimate recovery of par value. Both cash and stock dividends are reported as income.
Intangible Assets	INTANGIBLE ASSETS that are subject to amortization, including core deposit intangibles, are being amortized on both the straight-line and accelerated basis over three to twenty years. Intangible assets are periodically evaluated as to the recoverability of their carrying value.
Goodwill	GOODWILL is maintained by applying the provisions of ASC 350. For purchase acquisitions, the Corporation is required to record the assets acquired, including identified intangible assets, and the liabilities assumed at their fair value, which in many instances involves estimates based on third party valuations, such as appraisals, or internal valuations based on discounted cash flow analysis or other valuation techniques that may include estimates of attrition, inflation, asset growth rates or other relevant factors. In addition, the determination of the useful lives for which an intangible asset will be amortized is subjective.
	Under ASC 350, Intangibles – Goodwill and Other, the Corporation is required to evaluate goodwill for impairment on an annual basis, as well as on an interim basis, if events or changes indicate that the asset may be impaired, indicating that the carrying value may not be recoverable. The Corporation has historically elected to test for goodwill impairment as of October 1 of each year and has determined that no impairment exists.
Bank Owned Life Insurance	BANK OWNED LIFE INSURANCE has been purchased on certain employees and directors of the Corporation. The Corporation records the life insurance at the amount that can be realized under the insurance contract at the balance sheet date, which is the cash surrender value adjusted for other charges or amounts due that are probable at settlement.
Other Real Estate Owned	OTHER REAL ESTATE OWNED consists of assets acquired through, or in lieu of, loan foreclosure and are held for sale. They are initially recorded at fair value less cost to sell at the date of foreclosure, establishing a new cost basis.  Subsequent to foreclosure, valuations are periodically performed by management and the assets are carried at the lower of carrying amount or fair value less cost to sell.  Revenue and expenses from operations and changes in the valuation are included in net income or expense from foreclosed assets. Other real estate owned also includes bank premises qualifying as held for sale. Bank premises are transferred at the lower of carrying value or fair value less cost to sell.
Derivative Instruments	DERIVATIVE INSTRUMENTS are carried at the fair value of the derivatives and reflects the estimated amounts that would have been received to terminate these contracts at the reporting date based upon pricing or valuation models applied to current market information.
	As part of the asset/liability management program, the Corporation will utilize, from time to time, interest rate floors, caps or swaps to reduce its sensitivity to interest rate fluctuations. These are derivative instruments, which are recorded as assets or liabilities in the consolidated balance sheets at fair value. Changes in the fair values of derivatives are reported in the consolidated statements of operations or other comprehensive income (“OCI”) depending on the use of the derivative and whether the instrument qualifies for hedge accounting. The key criterion for the hedge accounting is that the hedged relationship must be highly effective in achieving offsetting changes in those cash flows that are attributable to the hedged risk, both at inception of the hedge and on an ongoing basis.
	Derivatives that qualify for the hedge accounting treatment are designated as either: a hedge of the fair value of the recognized asset or liability or of an unrecognized firm commitment (a fair value hedge) or a hedge of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (a cash flow hedge). To date, the Corporation has only entered into a cash flow hedge. For cash flow hedges, changes in the fair values of the derivative instruments are reported in OCI to the extent the hedge is effective. The gains and losses on derivative instruments that are reported in OCI are reflected in the consolidated statements of income in the periods in which the results of operations are impacted by the variability of the cash flows of the hedged item. Generally, net interest income is increased or decreased by amounts receivable or payable with respect to the derivatives, which qualify for hedge accounting. At inception of the hedge, the Corporation establishes the method it uses for assessing the effectiveness of the hedging derivative and the measurement approach for determining the ineffective aspect of the hedge. The ineffective portion of the hedge, if any, is recognized currently in the consolidated statements of operations. The Corporation excludes the time value expiration of the hedge when measuring ineffectiveness.
	The Corporation offers interest rate derivative products (e.g. interest rate swaps) to certain of its high-quality commercial borrowers. This product allows customers to enter into an agreement with the Corporation to swap their variable rate loan to a fixed rate. These derivative products are designed to reduce, eliminate or modify the risk of changes in the borrower’s interest rate or market price risk. The extension of credit incurred through the execution of these derivative products is subject to the same approvals and rigorous underwriting standards as the related traditional credit product. The Corporation limits its risk exposure to these products by entering into a mirror-image, offsetting swap agreement with a separate, well-capitalized and rated counterparty previously approved by the Credit and Asset Liability Committee. By using these interest rate swap arrangements, the Corporation is also better insulated from the interest rate risk associated with underwriting fixed-rate loans. These derivative contracts are not designated against specific assets or liabilities under ASC 815, Derivatives and Hedging, and, therefore, do not qualify for hedge accounting. The derivatives are recorded on the balance sheet at fair value and changes in fair value of both the customer and the offsetting swap agreements are recorded (and essentially offset) in non-interest income. The fair value of the derivative instruments incorporates a consideration of credit risk (in accordance with ASC 820), resulting in some volatility in earnings each period.
Income Tax	INCOME TAX in the consolidated statements of income includes deferred income tax provisions or benefits for all significant temporary differences in recognizing income and expenses for financial reporting and income tax purposes. The Corporation files consolidated income tax returns with its subsidiaries.
	The Corporation adopted the provisions of the ASC 740, Income Taxes, which prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. ASC 740 also provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure and transition. As a result of the implementation of ASC 740, the Corporation did not identify any uncertain tax positions that it believes should be recognized in the financial statements. The tax years still subject to examination by taxing authorities are years subsequent to 2010.
Stock Option and Restricted Stock Award Plans	STOCK OPTION AND RESTRICTED STOCK AWARD PLANS are maintained by the Corporation. The compensation costs are recognized for stock options and restricted stock awards issued to employees and directors based on the fair value of these awards at the date of grant. A Black-Scholes model is utilized to estimate the fair value of stock options.  The market price of the Corporation’s common stock at the date of grant is used for restricted stock awards. Compensation expense is recognized over the appropriate service period, which is generally two or three years.
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 Corporation 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 Corporation 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.
Net Income Per Share	NET INCOME PER SHARE is computed by dividing net income available to common shareholders by the weighted-average number of shares of common stock outstanding. Diluted net income per share is computed by dividing net income available to common shareholders by the weighted-average number of shares of common stock outstanding, plus the dilutive effect of outstanding stock options and nonvested restricted stock.
Reclassifications	RECLASSIFICATIONS have been made to prior financial statements to conform to the current financial statement presentation. These reclassifications had no effect on net income.

Purchase_and_Assumption_Tables

Purchase and Assumption (Tables)	12 Months Ended
	Dec. 31, 2014
Business Acquisition [Line Items]
Acquired Loans Accounted With ASC 310 30	The following table presents loans acquired during the periods ending December 31, 2014 and 2013, for which it was probable at acquisition that all contractually required payments would not be collected:
		Community - 2014		CFS - 2013
	Contractually required payments receivable at acquisition date	$	26,032	$	109,839
	Nonaccretable difference	3,498		22,679
	Expected cash flows at acquisition date	22,534		87,160
	Accretable difference	2,234		3,502
	Basis in loans at acquisition date	$	20,300	$	83,658
SCB Bank
Business Acquisition [Line Items]
Assets and Liabilities of SCB Recorded at Provisional Fair Value	The assets and liabilities of SCB Bank were recorded at the respective acquisition date provisional fair values, and identifiable intangible assets were recorded at provisional fair value.
	Assets			Liabilities
	Cash and due from banks (1)	$	29,113	Deposits:
	Investment securities, available for sale	18,896		Non-interest bearing	$	13,715
	Federal Home Loan Bank stock	1,761		NOW accounts	14,746
	Loans:			Savings and money market	25,843
	Commercial	51,042		Certificate of deposit	71,605
	Residential mortgage	11,181		Total Deposits	125,909
	Installment	31,570
	Total Loans	93,793		Federal Home Loan Bank advances	10,286
				Other liabilities	804
	Premises	1,516		Total Liabilities Assumed	$	136,999
	Core deposit intangible	484
	Other assets	560		Net Gain on Acquisition	$	9,124
	Total Assets Purchased	$	146,123
	-1	Includes $17,200,000 cash received from the FDIC.
Acquired Loans Accounted With ASC 310 30	In accordance with ASC 310-30 (formerly Statement of Position (“SOP”) 03-3 as of February 10, 2012, loans acquired during 2012 for which it was probable at acquisition that all contractually required payments would not be collected are as follows:
	Preliminary estimate of contractually required principal and interest at acquisition	$	31,143
	Preliminary estimate of contractual cash flows not expected to be collected (nonaccretable differences)	9,688
	Preliminary estimate of expected cash flows at acquisition	21,455
	Preliminary estimate of interest component of expected cash flows (accretable discount)	4,152
	Preliminary estimate of fair value of acquired loans accounted for under ASC 310-30	$	17,303

Business_Combination_Tables

Business Combination (Tables)	12 Months Ended
	Dec. 31, 2014
Business Acquisition [Line Items]
Schedule of pro forma information from acquisition	The following schedule includes pro forma results for the periods ended December 31, 2014, 2013 and 2012 as if the Community and CFS acquisitions had occurred as of the beginning of the comparable prior annual reporting period.
		2014			2013		2012
	Total revenue (net interest income plus other income)	$	263,070		$	253,668	$	266,034
	Net income	$	61,572		$	39,979	$	50,092
	Net income available to common shareholders	$	61,572		$	37,599	$	45,553
	Earnings per share:
	Basic	$	1.63		$	0.98	$	1.28
	Diluted	$	1.61		$	0.97	$	1.27
Merger with Community Bancshares, Inc.
Business Acquisition [Line Items]
Schedule of preliminary valuations of the fair value of assets acquired and liabilities assumed	Prior to the end of the one year measurement period for finalizing the purchase price allocation, if information becomes available which would indicate adjustments are required to the purchase price allocation, such adjustments will be included in the purchase price allocation retrospectively.
		Fair Value
	Cash and cash equivalents	$	4,124
	Interest -bearing time deposits	16,526
	Investment Securities, available for sale	76,807
	Loans	145,064
	Premises and equipment	3,610
	Federal Home Loan Bank stock	1,950
	Interest Receivable	767
	Cash surrender value of life insurance	3,266
	Other real estate owned	6,662
	Taxes, deferred and receivable	3,348
	Other assets	167
	Deposits	(228,424		)
	Interest payable	(98		)
	Other liabilities	(3,014		)
	Net tangible assets acquired	$	30,755
	Core deposit intangible	4,658
	Goodwill	13,776
	Purchase price	$	49,189
Merger with CFS Bancorp, Inc. (Citizens)
Business Acquisition [Line Items]
Schedule of preliminary valuations of the fair value of assets acquired and liabilities assumed	The purchase price for the CFS acquisition was allocated as follows:
		Fair Value
	Cash and cash equivalents	$	10,992
	Interest-bearing time deposits	213,379
	Investment securities available for sale	15,913
	Investment securities held to maturity	14,372
	Mortgage loans held for sale	189
	Loans	603,114
	Premises and equipment	19,643
	Federal Home Loan Bank stock	6,188
	Interest receivable	1,770
	Cash surrender value of life insurance	36,555
	Other real estate owned	12,857
	Tax asset, deferred and receivable	30,717
	Other assets	111,656
	Deposits	(955,432		)
	Securities sold under repurchase agreements	(9,830		)
	Federal Home Loan Bank advances	(15,000		)
	Interest payable	(294		)
	Other liabilities	(16,033		)
	Net tangible assets acquired	$	80,756
	Core deposit intangible	7,313
	Goodwill	47,573
	Purchase price	$	135,642

Investment_Securities_Tables

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Amortized Cost and Approximate Fair Values of Securities	The amortized cost, gross unrealized gains, gross unrealized losses and approximate market value of the Corporation's investment securities at the dates indicated were:
		Amortized Cost			Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	Available for sale at December 31, 2014
	U.S. Government-sponsored agency securities	$	100		$	9			$	109
	State and municipal	216,915			11,801		$	123	228,593
	U.S. Government-sponsored mortgage-backed securities	310,460			8,771		127		319,104
	Corporate obligations	31							31
	Equity securities	1,706							1,706
	Total available for sale	529,212			20,581		250		549,543
	Held to maturity at December 31, 2014
	State and municipal	204,443			5,716		96		210,063
	U.S. Government-sponsored mortgage-backed securities	426,645			11,527		512		437,660
	Total held to maturity	631,088			17,243		608		647,723
	Total Investment Securities	$	1,160,300		$	37,824	$	858	$	1,197,266
	Available for sale at December 31, 2013
	U.S. Treasury	$	15,914		$	80	$	21	$	15,973
	U.S. Government-sponsored agency securities	3,550			12		17		3,545
	State and municipal	231,005			3,878		3,896		230,987
	U.S. Government-sponsored mortgage-backed securities	279,299			3,926		1,973		281,252
	Corporate obligations	6,374					3,636		2,738
	Equity securities	1,706							1,706
	Total available for sale	537,848			7,896		9,543		536,201
	Held to maturity at December 31, 2013
	State and municipal	145,941			62		91		145,912
	U.S. Government-sponsored mortgage-backed securities	413,437			5,220		3,722		414,935
	Total held to maturity	559,378			5,282		3,813		560,847
	Total Investment Securities	$	1,097,226		$	13,178	$	13,356	$	1,097,048
Debt Securities Credit Loss Recognized in Income, and Other Losses Recorded in Other Comprehensive Income	The following table provides information about debt securities for which only a credit loss was recognized in income and other losses were recorded in other comprehensive income.
		Accumulated Credit Losses in			Accumulated Credit Losses in
		2014			2013
	Credit losses on debt securities held:
	Balance, January 1	$	11,355		$	11,355
	Reductions for previous other-than-temporary losses realized on securities sold during the year	(10,855		)
	Balance, December 31	$	500		$	11,355
Investments' Gross Unrealized Losses and Fair Value Aggregated by Investment Category and Length of Time in Continuous Unrealized Loss Position	The following table shows the Corporation’s gross unrealized losses and fair value, aggregated by investment category and length of time the individual securities have been in a continuous unrealized loss position at December 31, 2014 and 2013:
		Less than					12 Months				Total
		12 Months					or Longer
		Fair			Gross		Fair		Gross		Fair		Gross
		Value			Unrealized		Value		Unrealized		Value		Unrealized
					Losses				Losses				Losses
	Temporarily Impaired Available for Sale Securities at December 31, 2014
	State and municipal	$	1,256		$	7	$	9,850	$	116	$	11,106	$	123
	U.S. Government-sponsored mortgage-backed securities	2,186			13		5,447		114		7,633		127
	Total Temporarily Impaired Available for Sale Securities	3,442			20		15,297		230		18,739		250
	Temporarily Impaired Held to Maturity Securities at December 31, 2014
	State and municipal	5,119			96		250				5,369		96
	U.S. Government-sponsored mortgage-backed securities	9,791			82		38,491		430		48,282		512
	Total Temporarily Impaired Held to Maturity Securities	14,910			178		38,741		430		53,651		608
	Total Temporarily Impaired Investment Securities	$	18,352		$	198	$	54,038	$	660	$	72,390	$	858
		Less than					12 Months				Total
		12 Months					or Longer
		Fair			Gross		Fair		Gross		Fair		Gross
		Value			Unrealized		Value		Unrealized		Value		Unrealized
					Losses				Losses				Losses
	Temporarily Impaired Available for Sale Securities at December 31, 2013
	U.S. Treasury	$	4,875		$	21					$	4,875	$	21
	U.S. Government-sponsored agency securities	3,433			17						3,433		17
	State and municipal	111,791			3,840		$	583	$	56	112,374		3,896
	U.S. Government-sponsored mortgage-backed securities	117,866			1,701		2,683		272		120,549		1,973
	Corporate obligations						2,711		3,636		2,711		3,636
	Total Temporarily Impaired Available for Sale Securities	237,965			5,579		5,977		3,964		243,942		9,543
	Temporarily Impaired Held to Maturity Securities at December 31, 2013
	State and municipal	17,318			91		184				17,502		91
	U.S. Government-sponsored mortgage-backed securities	213,048			3,462		2,640		260		215,688		3,722
	Total Temporarily Impaired Held to Maturity Securities	230,366			3,553		2,824		260		233,190		3,813
	Total Temporarily Impaired Investment Securities	$	468,331		$	9,132	$	8,801	$	4,224	$	477,132	$	13,356
Amortized Cost and Fair Value of Available for Sale Securities and Held to Maturity Securities by Contractual Maturity	Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties.
		Available for Sale					Held to Maturity
		Amortized Cost			Fair Value		Amortized Cost		Fair Value
	Maturity Distribution at December 31, 2014
	Due in one year or less	$	3,127		$	3,153	$	6,258	$	6,329
	Due after one through five years	9,565			9,840		18,440		18,930
	Due after five through ten years	48,675			50,889		85,997		87,903
	Due after ten years	155,679			164,851		93,748		96,901
		217,046			228,733		204,443		210,063
	U.S. Government-sponsored mortgage-backed securities	310,460			319,104		426,645		437,660
	Equity securities	1,706			1,706
	Total Investment Securities	$	529,212		$	549,543	$	631,088	$	647,723

Loans_and_Allowance_Tables

Loans and Allowance (Tables)	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Composition of Loan Portfolio by Loan Class	The following table illustrates the composition of the Corporation’s loan portfolio by loan class for the years indicated:
		31-Dec-14				31-Dec-13
	Commercial and industrial loans	$	896,688			$	761,705
	Agricultural production financing and other loans to farmers	104,927				114,348
	Real estate loans:
	Construction	207,221				177,082
	Commercial and farmland	1,672,661				1,611,809
	Residential	647,315				616,385
	Home equity	286,529				255,223
	Individuals' loans for household and other personal expenditures	73,400				69,783
	Lease financing receivables, net of unearned income	1,106				1,545
	Other loans	35,018				24,529
	Loans	3,924,865				3,632,409
	Allowance for loan losses	(63,964		)		(67,870		)
	Net Loans	$	3,860,901			$	3,564,539
Changes in Allowance for Loan Losses	The following table summarizes changes in the allowance for loan losses by loan segment for the twelve months ended December 31, 2014, 2013 and 2012:
		Twelve Months Ended December 31, 2014
		Commercial				Commercial Real Estate			Consumer			Residential			Finance				Total
															Leases
	Allowance for loan losses:
	Balances, January 1	$	27,176			$	23,102		$	2,515		$	15,077						$	67,870
	Provision for losses	3,459				(464		)	423			(839		)	$	(19	)		2,560
	Recoveries on loans	5,435				3,297			377			1,783			24				10,916
	Loans charged off	(7,246		)		(6,608		)	(657		)	(2,869		)	(2		)		(17,382		)
	Balances, December 31, 2014	$	28,824			$	19,327		$	2,658		$	13,152		$	3			$	63,964
		Twelve Months Ended December 31, 2013
		Commercial				Commercial Real Estate			Consumer			Residential			Finance				Total
															Leases
	Allowance for loan losses:
	Balances, January 1	$	25,913			$	26,703		$	2,593		$	14,157						$	69,366
	Provision for losses	2,794				340			(11		)	3,514			$	11			6,648
	Recoveries on loans	4,586				3,552			556			1,292			4				9,990
	Loans charged off	(6,117		)		(7,493		)	(623		)	(3,886		)	(15		)		(18,134		)
	Balances, December 31, 2013	$	27,176			$	23,102		$	2,515		$	15,077						$	67,870
		Twelve Months Ended December 31, 2012
		Commercial				Commercial Real Estate			Consumer			Residential			Finance				Total
															Leases
	Allowance for loan losses:
	Balances, January 1	$	17,731			$	37,919		$	2,902		$	12,343		$	3			$	70,898
	Provision for losses	14,749				(2,546		)	126			6,176			29				18,534
	Recoveries on loans	1,744				3,652			695			1,113			2				7,206
	Loans charged off	(8,311		)		(12,322		)	(1,130		)	(5,475		)	(34		)		(27,272		)
	Balances, December 31, 2012	$	25,913			$	26,703		$	2,593		$	14,157						$	69,366
Allowance for Credit Losses and Loan Portfolio by Loan Segment	The following tables show the Corporation’s allowance for loan losses and loan portfolio by loan segment for the years indicated:
		December 31, 2014
		Commercial				Commercial			Consumer			Residential			Finance				Total
						Real Estate									Leases
	Allowance balances:
	Individually evaluated for impairment	$	1,455			$	470					$	194						$	2,119
	Collectively evaluated for impairment	27,369				18,207			$	2,658		12,958			$	3			61,195
	Loans acquired with deteriorated credit quality					650													650
	Total Allowance for Loan Losses	$	28,824			$	19,327		$	2,658		$	13,152		$	3			$	63,964
	Loan balances:
	Individually evaluated for impairment	$	16,108			$	23,963					$	4,022						$	44,093
	Collectively evaluated for impairment	1,011,122				1,796,797			$	73,400		925,282			$	1,106			3,807,707
	Loans acquired with deteriorated credit quality	9,403				59,122						4,540							73,065
	Loans	$	1,036,633			$	1,879,882		$	73,400		$	933,844		$	1,106			$	3,924,865
		December 31, 2013
		Commercial				Commercial			Consumer			Residential			Finance				Total
						Real Estate									Leases
	Allowance balances:
	Individually evaluated for impairment	$	585			$	763					$	6						$	1,354
	Collectively evaluated for impairment	26,493				22,208			$	2,515		15,071							66,287
	Loans acquired with deteriorated credit quality	98				131													229
	Total Allowance for Loan Losses	$	27,176			$	23,102		$	2,515		$	15,077						$	67,870
	Loan balances:
	Individually evaluated for impairment	$	10,240			$	29,007					$	2,820						$	42,067
	Collectively evaluated for impairment	882,794				1,690,285			$	69,783		867,094			$	1,545			3,511,501
	Loans acquired with deteriorated credit quality	7,548				69,599						1,694							78,841
	Loans	$	900,582			$	1,788,891		$	69,783		$	871,608		$	1,545			$	3,632,409
Summary of Non-Accrual Loans by Loan class	The following table summarizes the Corporation’s non-accrual loans by loan class for the years indicated:
		31-Dec-14				31-Dec-13
	Commercial and industrial loans	$	7,048			$	9,283
	Agriculture production financing and other loans to farmers	5,800				30
	Real estate loans:
	Construction	1,439				4,978
	Commercial and farmland	19,350				28,095
	Residential	12,933				12,068
	Home equity	1,988				1,667
	Individuals' loans for household and other personal expenditures	231				117
	Other loans					164
	Total	$	48,789			$	56,402
Composition of Impaired Loans by Loan Class	The following tables show the composition of the Corporation’s commercial impaired loans by loan class for the years indicated:
		December 31, 2014
		Unpaid Principal				Recorded			Related			Average Recorded Investment			Interest Income Recognized
		Balance				Investment			Allowance
	Impaired loans with no related allowance:
	Commercial and industrial loans	$	35,514			$	18,029					$	18,711		$	362
	Agriculture production financing and other loans to farmers	26				22						26
	Real estate loans:
	Construction	12,956				9,318						9,837			427
	Commercial and farmland	95,856				68,187						70,844			3,389
	Residential	10,591				6,839						6,987			119
	Home equity	3,590				398						402
	Other loans	30
	Total	$	158,563			$	102,793					$	106,807		$	4,297
	Impaired loans with related allowance:
	Commercial and industrial loans	$	1,766			$	1,684		$	1,055		$	1,721		$	40
	Agriculture production financing and other loans to farmers	6,777				5,777			400			8,044			1
	Real estate loans:
	Commercial and farmland	7,159				4,971			1,120			4,999			24
	Residential	1,001				998			194			1,000
	Total	$	16,703			$	13,430		$	2,769		$	15,764		$	65
	Total Impaired Loans	$	175,266			$	116,223		$	2,769		$	122,571		$	4,362
		December 31, 2013
		Unpaid Principal				Recorded			Related			Average Recorded Investment			Interest Income Recognized
		Balance				Investment			Allowance
	Impaired loans with no related allowance:
	Commercial and industrial loans	$	35,066			$	16,371					$	19,209		$	192
	Agriculture production financing and other loans to farmers	32				30						32
	Real estate loans:
	Construction	16,109				10,625						11,621			117
	Commercial and farmland	128,073				83,033						84,057			1,663
	Residential	6,746				3,910						4,236			75
	Home equity	3,299				112						225
	Other loans	454				172						181			1
	Total	$	189,779			$	114,253					$	119,561		$	2,048
	Impaired loans with related allowance:
	Commercial and industrial loans	$	1,390			$	1,216		$	683		$	1,240		$	9
	Real estate loans:
	Construction
	Commercial and farmland	4,657				4,215			894			4,291			9
	Residential	74				71			6			76
	Total	$	6,121			$	5,502		$	1,583		$	5,607		$	18
	Total Impaired Loans	$	195,900			$	119,755		$	1,583		$	125,168		$	2,066
		December 31, 2012
		Unpaid Principal				Recorded			Related			Average Recorded Investment			Interest Income Recognized
		Balance				Investment			Allowance
	Impaired loans with no related allowance:
	Commercial and industrial loans	$	28,532			$	11,730					$	15,089		$	124
	Real estate loans:
	Construction	9,787				5,164						6,471			66
	Commercial and farmland	58,173				43,204						46,788			1,211
	Residential	8,820				6,215						7,129			83
	Home equity	4,199				1,006						1,022			13
	Other loans	83				14						18			1
	Total	$	109,594			$	67,333					$	76,517		$	1,498
	Impaired loans with related allowance:
	Commercial and industrial loans	$	4,415			$	4,155		$	1,628		$	4,225		$	33
	Real estate loans:
	Construction	1,202				1,058			105			1,175
	Commercial and farmland	5,579				5,182			2,460			5,239			95
	Residential	1,722				1,451			50			1,458			75
	Total	$	12,918			$	11,846		$	4,243		$	12,097		$	203
	Total Impaired Loans	$	122,512			$	79,179		$	4,243		$	88,614		$	1,701
Credit Quality of Loan Portfolio by Loan Class	The following tables summarize the credit quality of the Corporation’s loan portfolio, by loan class for the years indicated.  Consumer non-performing loans include accruing consumer loans 90 plus days delinquent and consumer non-accrual loans.  The entire balance of a loan is considered delinquent if the minimum payment contractually required to be made is not received by the specified date. Loans that evidenced deterioration of credit quality since origination and it was probable, at acquisition, that all contractually required payments would not be collected are included in the applicable categories below.
		December 31, 2014
		Commercial Pass				Commercial Special Mention			Commercial Substandard			Commercial Doubtful			Commercial Loss		Consumer Performing				Consumer				Total
																					Non Performing
	Commercial and industrial loans	$	823,732			$	24,455		$	48,226		$	275												$	896,688
	Agriculture production financing and other loans to farmers	96,155				1,195			7,577																104,927
	Real estate loans:
	Construction	185,394				3,164			2,928								$	15,588			$	147			207,221
	Commercial and farmland	1,552,781				29,484			90,161												235				1,672,661
	Residential	149,430				6,321			10,918								470,972				9,674				647,315
	Home equity	6,368				12			690								277,571				1,888				286,529
	Individuals' loans for household and other personal expenditures																73,165				235				73,400
	Lease financing receivables, net of unearned income	998							108																1,106
	Other loans	35,018																							35,018
	Loans	$	2,849,876			$	64,631		$	160,608		$	275				$	837,296			$	12,179			$	3,924,865
		December 31, 2013
		Commercial Pass				Commercial Special Mention			Commercial Substandard			Commercial Doubtful			Commercial Loss		Consumer Performing				Consumer				Total
																					Non Performing
	Commercial and industrial loans	$	708,835			$	11,332		$	41,013		$	525												$	761,705
	Agriculture production financing and other loans to farmers	114,318							30																114,348
	Real estate loans:
	Construction	162,976				1,132			12,029												$	945			177,082
	Commercial and farmland	1,473,714				57,676			80,184												235				1,611,809
	Residential	143,657				2,232			11,494			136					$	448,494			10,372				616,385
	Home equity	6,194				35			1,184								246,101				1,709				255,223
	Individuals' loans for household and other personal expenditures																69,666				117				69,783
	Lease financing receivables, net of unearned income	1,420							125																1,545
	Other loans	24,334							195																24,529
	Loans	$	2,635,448			$	72,407		$	146,254		$	661				$	764,261			$	13,378			$	3,632,409
Past Due Aging of Loan Portfolio by Loan Class	The following tables illustrate the past due aging of the Corporation’s loan portfolio, by loan class, for the years indicated:
		December 31, 2014
		Current				30-59 Days			60-89 Days			Loans > 90 Days			Non-Accrual				Total Past Due				Total
						Past Due			Past Due			And Accruing							& Non-Accrual
	Commercial and industrial loans	$	882,596			$	4,006		$	53		$	2,985		$	7,048			$	14,092			$	896,688
	Agriculture production financing and other loans to farmers	98,236				891									5,800				6,691				104,927
	Real estate loans:
	Construction	204,683				1,017			82						1,439				2,538				207,221
	Commercial and farmland	1,642,016				9,846			778			671			19,350				30,645				1,672,661
	Residential	626,821				4,876			1,831			854			12,933				20,494				647,315
	Home equity	282,828				1,213			352			148			1,988				3,701				286,529
	Individuals' loans for household and other personal expenditures	72,853				258			53			5			231				547				73,400
	Lease financing receivables, net of unearned income	1,106																					1,106
	Other loans	35,018																					35,018
	Loans	$	3,846,157			$	22,107		$	3,149		$	4,663		$	48,789			$	78,708			$	3,924,865
		December 31, 2013
		Current				30-59 Days			60-89 Days			Loans > 90 Days			Non-Accrual				Total Past Due				Total
						Past Due			Past Due			And Accruing							& Non-Accrual
	Commercial and industrial loans	$	749,020			$	2,628		$	774					$	9,283			$	12,685			$	761,705
	Agriculture production financing and other loans to farmers	114,305				13									30				43				114,348
	Real estate loans:
	Construction	171,046				1,058									4,978				6,036				177,082
	Commercial and farmland	1,573,403				3,807			5,801			$	703		28,095				38,406				1,611,809
	Residential	595,192				7,156			1,475			494			12,068				21,193				616,385
	Home equity	251,188				1,652			563			153			1,667				4,035				255,223
	Individuals' loans for household and other personal expenditures	69,061				550			55						117				722				69,783
	Lease financing receivables, net of unearned income	1,545																					1,545
	Other loans	24,365													164				164				24,529
	Loans	$	3,549,125			$	16,864		$	8,668		$	1,350		$	56,402			$	83,284			$	3,632,409
Schedules of Troubled Debt Restructuring	The following tables summarize troubled debt restructures that occurred during the twelve months ended December 31, 2014 and 2013, that subsequently defaulted during the period indicated and remained in default at period end. For purposes of this schedule, a loan is considered in default if it is 30 or more days past due.
		Twelve Months Ended December 31, 2014
		Number of Loans			Recorded Balance
	Real estate loans:
	Residential	1			$	70
	Total	1			$	70
		Twelve Months Ended December 31, 2013
		Number of Loans			Recorded Balance
	Commercial and industrial loans	3			$	173
	Real estate loans:
	Commercial and farmland	2			1,034
	Total	5			$	1,207
	The following tables summarize troubled debt restructurings that occurred during the periods ended December 31, 2014 and 2013:
		December 31, 2014
		Pre-Modification				Post-Modification			Number
		Recorded Balance				Recorded Balance			of Loans
	Real estate loans:
	Commercial and farmland	$	259			$	259		1
	Residential	632				622			9
	Home equity	320				350			11
	Individuals' loans for household and other personal expenditures	26				26			2
	Total	$	1,237			$	1,257		23
		December 31, 2013
		Pre-Modification				Post-Modification			Number
		Recorded Balance				Recorded Balance			of Loans
	Commercial and industrial loans	$	295			$	316		5
	Real estate loans:
	Commercial and farmland	6,506				5,492			11
	Residential	809				804			12
	Individuals' loans for household and other personal expenditures	143				145			4
	Total	$	7,753			$	6,757		32
	The following tables show the recorded investment of troubled debt restructurings, by modification type, that occurred during the years indicated:
		31-Dec-14
		Term				Rate			Combination			Total
		Modification				Modification						Modification
	Real estate loans:
	Commercial and farmland	$	288									$	288
	Residential	31				$	218		$	360		609
	Home equity					100			243			343
	Individuals' loans for household and other personal expenditures								23			23
	Total	$	319			$	318		$	626		$	1,263
		31-Dec-13
		Term				Rate			Combination			Total
		Modification				Modification						Modification
	Commercial and industrial loans	$	207						$	60		$	267
	Real estate loans:
	Commercial and farmland	1,388							1,985			3,373
	Residential	167				$	237		351			755
	Individuals' loans for household and other personal expenditures	61				38			25			124
	Total	$	1,823			$	275		$	2,421		$	4,519

Accounting_For_Certain_Loans_A1

Accounting For Certain Loans Acquired In a Purchase (Tables)	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Schedule of Carrying Values of Certain Loans Acquired in Transfer Not Accounted for as Debt Securities	The following table includes the outstanding balance and carrying amount of all the performing and non-performing acquired loans, which are included in the Corporation's balance sheet at December 31, 2014 and 2013.
		31-Dec-14												December 31, 2013
		Community			CFS			SCB			Total			CFS			SCB			Total
	Outstanding Balance:
	Commercial and industrial loans	$	8,168		$	64,897		$	6,059		$	79,124		$	81,303		$	8,184		$	89,487
	Agricultural production financing and other loans to farmers	1,100						893			1,993						1,161			1,161
	Real estate loans:
	Construction	19,063			9,113						28,176			17,962						17,962
	Commercial and farmland	74,600			251,002			15,593			341,195			311,631			23,418			335,049
	Residential	28,863			144,396			7,384			180,643			166,754			9,359			176,113
	Home Equity	9,881			39,244			15,758			64,883			49,042			18,236			67,278
	Individuals' loans for household and other personal expenditures	1,314			922			121			2,357			2,360			269			2,629
	Other Loans				86						86			$	132		$	407		$	539
	Total	$	142,989		$	509,660		$	45,808		$	698,457		$	629,184		$	61,034		$	690,218
	Carrying Amount	$	134,198		$	484,949		$	39,324		$	658,471		$	585,913		$	50,269		$	636,182
	Allowance				650						650						229			229
	Carrying Amount Net of Allowance	$	134,198		$	484,299		$	39,324		$	657,821		$	585,913		$	50,040		$	635,953
Schedule of Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement	ccretable yield, or income expected to be collected, and reclassifications from nonaccretable yield, are identified in the table below.
		Twelve months ended
		31-Dec-14												31-Dec-13									31-Dec-12
		Community			CFS			SCB			Total			CFS			SCB			Total			SCB
	Beginning balance				$	13,435		$	5,864		$	19,299					$	5,142		$	5,142		$	—
	Additions	$	5,687								5,687			$	13,599					13,599
	Accretion	(394		)	(6,431		)	(2,058		)	(8,883		)	(164		)	(2,071		)	(2,235		)	9,774
	Reclassification from nonaccretable	119			4,501			799			5,419						2,888			2,888			(4,632		)
	Disposals				(1,594		)	(492		)	(2,086		)				(95		)	(95		)	—
	Ending balance	$	5,412		$	9,911		$	4,113		$	19,436		$	13,435		$	5,864		$	19,299		$	5,142
Schedule Of Loans Acquired During Period For Which Contractually Required Payments Would Not Be Collected	The following table presents loans acquired during the periods ending December 31, 2014 and 2013, for which it was probable at acquisition that all contractually required payments would not be collected:
		Community - 2014			CFS - 2013
	Contractually required payments receivable at acquisition date	$	26,032		$	109,839
	Nonaccretable difference	3,498			22,679
	Expected cash flows at acquisition date	22,534			87,160
	Accretable difference	2,234			3,502
	Basis in loans at acquisition date	$	20,300		$	83,658

Premises_and_Equipment_Tables

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Schedule of Premises and Equipment	The following table summarizes the Corporation's premises and equipment as of December 31, 2014 and 2013:
		2014			2013
	Cost at December 31:
	Land	$	19,373		$	17,992
	Buildings and Leasehold Improvements	99,451			92,693
	Equipment	56,606			54,274
	Total Cost	175,430			164,959
	Accumulated Depreciation and Amortization	(97,739		)	(90,505		)
	Net	$	77,691		$	74,454
Schedule of Future Minimum Rental Payments for Operating Leases	The future minimum rental commitments required under the operating leases in effect at December 31, 2014, expiring at various dates through the year 2028 are as follows for the years ending December 31:
		Future Minimum Rental Commitments
	2015	$	2,778
	2016	2,207
	2017	1,514
	2018	844
	2019	537
	After 2019	2,724
	Total Future Minimum Obligations	$	10,604

Goodwill_Tables

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill Disclosure [Abstract]
Schedule of Goodwill	For additional details related to impairment testing, see the “GOODWILL” section of Management’s Discussion and Analysis of Financial Condition and Results of Operations included as Item 7 of this Annual Report on Form 10-K.
		2014		2013
	Balance, January 1	$	188,948	$	141,375
	Goodwill acquired	13,776		47,573
	Balance, December 31	$	202,724	$	188,948

Core_Deposit_and_Other_Intangi1

Core Deposit and Other Intangibles (Tables)	12 Months Ended
	Dec. 31, 2014
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Schedule of Core Deposit and Other Intangibles	The carrying basis and accumulated amortization of recognized core deposit and other intangibles are noted below.
		2014			2013
	Gross carrying amount	$	53,702		$	46,389
	Core deposit intangible and other intangibles acquired	4,658			7,313
	Accumulated amortization	(42,329		)	(39,884		)
	Core Deposit and Other Intangibles	$	16,031		$	13,818
Schedule of Estimated Amortization Expense	Estimated future amortization expense is summarized as follows:
		Amortization Expense
	2015	$	2,884
	2016	2,817
	2017	2,723
	2018	1,542
	2019	1,293
	After 2019	4,772
	Total Future Minimum Obligations	$	16,031

Deposits_Tables

Deposits (Tables)	12 Months Ended
	Dec. 31, 2014
Banking and Thrift [Abstract]
Schedule Of Deposits	The composition of the deposit portfolio is included in the table below for the years indicated:
		31-Dec-14		31-Dec-13
	Demand deposits	$	2,146,492	$	2,018,650
	Savings deposits	1,376,707		1,257,994
	Certificates and other time deposits of $100,000 or more	260,685		272,660
	Other certificates and time deposits	523,010		595,110
	Brokered deposits	333,800		87,054
	Total deposits	$	4,640,694	$	4,231,468
Schedule of Deposit Contractual Maturities, Excluding Demand and Savings	At December 31, 2014, the contractual maturities of time deposits are summarized as follows:
		Certificates and Other Time Deposits
	2015	$	469,352
	2016	256,921
	2017	144,348
	2018	87,234
	2019	52,792
	After 2019	106,848
		$	1,117,495

Borrowings_Tables

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Schedule of Debt	The following table summarizes the Corporation's borrowings as of December 31, 2014 and 2013:
		31-Dec-14		31-Dec-13
	Federal funds purchased	$	15,381	$	125,645
	Securities sold under repurchase agreements	124,539		148,672
	Federal Home Loan Bank advances	145,264		122,140
	Subordinated debentures and term loans	126,810		126,807
	Total Borrowings	$	411,994	$	523,264
Schedule of Maturities of Long-term Debt	Maturities of securities sold under repurchase agreements; Federal Home Loan Bank Advances, subordinated debentures and term loans as of December 31, 2014, are as follows:
	Maturities in Years Ending December 31:	Securities Sold		Federal Home		Subordinated
		Under Repurchase Agreements		Loan Bank		Debentures and
				Advances		Term Loans
	2015	$	124,539	$	30,780	$	108
	2016			41,225
	2017			15,018
	2018			25,637
	2019			12,503
	After 2019			20,101		126,702
		$	124,539	$	145,264	$	126,810

Derivative_Instruments_and_Hed1

Derivative Instruments and Hedging Activities (Tables)

12 Months Ended

Dec. 31, 2014

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Fair Value of Derivative Financial Instruments and Their Classification on Balance Sheet

The table below presents the fair value of the Corporation’s derivative financial instruments as well as their classification on the Balance Sheet as of December 31, 2014 and December 31, 2013.

Asset Derivatives

Liability Derivatives

December 31, 2014

December 31, 2013

December 31, 2014

December 31, 2013

Balance Sheet Location

Fair

Balance Sheet Location

Fair

Balance Sheet Location

Fair

Balance Sheet Location

Fair

Value

Value

Value

Value

Derivatives designated as hedging instruments:

Interest rate contracts

Other Assets

$

137

Other Assets

$

1,162

Other Liabilities

$

2,650

Other Liabilities

$

1,021

Derivatives not designated as hedging instruments:

Interest rate contracts

Other Assets

$

3,730

Other Assets

$

2,847

Other Liabilities

$

3,887

Other Liabilities

$

2,932

Effect of Derivative Financial Instruments on Income Statement

The tables below present the effect of the Corporation’s derivative financial instruments on the Income Statement for the years ended December 31, 2014, 2013 and 2012.

Derivatives Not

Location of Gain

Amount of Gain (Loss)

Amount of Gain (Loss)

Amount of Gain (Loss)

Designated as Hedging

(Loss) Recognized in

Recognized in Income on

Recognized in Income on

Recognized in Income on

Instruments under

Income on Derivative

Derivative for the Year Ended December 31, 2014

Derivative for the Year Ended December 31, 2013

Derivative for the Year Ended December 31, 2012

FASB ASC 815-10

Interest rate contracts

Other income

$

(73

)

$

247

$

(79

)

Derivatives in Cash Flow Hedging Relationships

Amount of Gain (Loss) Recognized in Other Comprehensive Income on Derivative

Location of Loss Reclassified from Accumulated Other Comprehensive Income (Effective Portion)

Amount of Loss Reclassified from Other Comprehensive Income into Income

(Effective Portion)

(Effective Portion)

For the Year Ended

For the Year Ended

2014

2013

2014

2013

2012

Interest rate products

$

(3,996

)

$

2,374

Interest expense

$

(1,411

)

$

(935

)

$

(217

)

Fair_Values_of_Financial_Instr1

Fair Values of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements of Assets and Liabilities Recognized in Consolidated Condensed Balance Sheets Measured at Fair Value	The following table presents the fair value measurements of assets and liabilities recognized in the accompanying balance sheets measured at fair value on a recurring basis and the level within the ASC 820-10 fair value hierarchy in which the fair value measurements fall at December 31, 2014 and 2013.
							Fair Value Measurements Using:
							Quoted Prices in Active		Significant Other Observable Inputs				Significant
							Markets for Identical Assets						Unobservable Inputs
	December 31, 2014		Fair Value				(Level 1)		(Level 2)				(Level 3)
	Available for sale securities:
	U.S. Government-sponsored agency securities		$	109					$	109
	State and municipal		228,593						221,982				$	6,611
	U.S. Government-sponsored mortgage-backed securities		319,104						319,104
	Corporate obligations		31										31
	Equity securities		1,706						1,702				4
	Interest rate swap asset		3,730						3,730
	Interest rate cap		137						137
	Interest rate swap liability		6,537						6,537
							Fair Value Measurements Using:
							Quoted Prices in Active		Significant Other Observable Inputs				Significant
							Markets for Identical Assets						Unobservable Inputs
	December 31, 2013		Fair Value				(Level 1)		(Level 2)				(Level 3)
	Available for sale securities:
	U.S. Treasury		$	15,973					$	15,973
	U.S. Government-sponsored agency securities		3,545						3,545
	State and municipal		230,987						223,752				$	7,235
	U.S. Government-sponsored mortgage-backed securities		281,252						281,252
	Corporate obligations		2,738										2,738
	Equity securities		1,706						1,702				4
	Interest rate swap asset		3,619						3,619
	Interest rate cap		390						390
	Interest rate swap liability		3,953						3,953
Reconciliation of Beginning and Ending Balances of Recurring Fair Value Measurements Recognized in Consolidated Condensed Balance Sheets using Significant Unobservable Level 3 Inputs	The following is a reconciliation of the beginning and ending balances of recurring fair value measurements recognized in the accompanying balance sheets using significant unobservable Level 3 inputs for year ended December 31, 2014 and 2013.
		Available for Sale Securities
		For The Year Ended
		December 31, 2014				December 31, 2013
	Beginning Balance	$	9,977			$	18,328
	Included in other comprehensive income	3,656				1,330
	Purchases, issuances, and settlements					7,590
	Transfers in/(out) of Level 3					(16,434		)
	Principal payments	(6,987		)		(837		)
	Ending balance	$	6,646			$	9,977
Transfer Between Levels 1, 2 and 3 and Reasons For Transfers	TRANSFERS BETWEEN LEVELS
		Quoted Prices in Active		Significant Other Observable Inputs				Significant
		Markets for Identical Assets						Unobservable Inputs
	31-Dec-13	(Level 1)		(Level 2)				(Level 3)				Reason for Transfer
	Transfers to/(from) Level:
	Available for sale securities			$	(350	)		$	350			Selected state and municipal securities were transferred from Level 2 to Level 3 due to limited availability of similar securities in active markets.
	Available for sale securities transferred to held to maturity							$	(16,784	)		Selected state and municipal securities were transferred from available for sale to held to maturity. These securities are valued at amortized cost and are no longer classified within the fair value hierarchy.
Description of Valuation Methodologies Used for Instruments Measured at Fair Value on a Non-Recurring Basis and Recognized in Consolidated Condensed Balance Sheets	Following is a description of valuation methodologies used for instruments measured at fair value on a non-recurring basis and recognized in the accompanying balance sheets, as well as the general classification of such instruments pursuant to the valuation hierarchy for year ended December 31, 2014 and 2013.
							Fair Value Measurements Using
							Quoted Prices in Active		Significant Other Observable Inputs		Significant
							Markets for Identical Assets				Unobservable Inputs
	December 31, 2014		Fair Value				(Level 1)		(Level 2)		(Level 3)
	Impaired Loans (collateral dependent)		$	17,134							$	17,134
	Other real estate owned		$	5,155							$	5,155
							Fair Value Measurements Using
							Quoted Prices in Active		Significant Other Observable Inputs		Significant
							Markets for Identical Assets				Unobservable Inputs
	December 31, 2013		Fair Value				(Level 1)		(Level 2)		(Level 3)
	Impaired Loans (collateral dependent)		$	12,117							$	12,117
	Other real estate owned		$	6,877							$	6,877
Unobservable Inputs Used in Recurring and Nonrecurring Level 3 Fair Value Measurements Other Than Goodwill	The following table presents quantitative information about unobservable inputs used in recurring and nonrecurring Level 3 fair value measurements, other than goodwill, at December 31, 2014 and 2013.
	December 31, 2014	Fair Value				Valuation Technique		Unobservable Inputs		Range (Weighted-Average)
	State and municipal securities	$	6,611			Discounted cash flow		Maturity Call Date		1 month to 15 years
								US Muni BQ curve		A- to BBB-
								Discount rate		.90% - 5%
	Corporate obligations and Equity securities	$	35			Discounted cash flow		Risk free rate		3 month LIBOR
								plus Premium for illiquidity		plus 200 bps
	Impaired loans (collateral dependent)	$	17,134			Collateral based measurements		Discount to reflect current market conditions and ultimate collectability		0% - 50% (3%)
	Other real estate owned	$	5,155			Appraisals		Discount to reflect current market conditions		0% - 20% (7%)
	December 31, 2013	Fair Value				Valuation Technique		Unobservable Inputs		Range (Weighted-Average)
	State and municipal securities	$	7,235			Discounted cash flow		Maturity Call Date		1 month to 15 years
								US Muni BQ curve		A- to BBB-
								Discount rate		1% - 5%
	Corporate obligations and Equity securities	$	2,742			Discounted cash flow		Risk free rate		3 month LIBOR
								plus Premium for illiquidity		plus 200 bps
	Impaired loans (collateral dependent)	$	12,117			Collateral based measurements		Discount to reflect current market conditions and ultimate collectability		0% - 50% (3%)
	Other real estate owned	$	6,877			Appraisals		Discount to reflect current market conditions		0% - 20% (2%)
Estimated Fair Values of Financial Instruments	The following table presents estimated fair values of the Corporation's financial instruments and the level within the fair value hierarchy in which the fair value measurements fall at December 31, 2014 and 2013.
		2014
		Carrying				Quoted Prices in Active Markets for Identical Assets				Significant Other Observable Inputs				Significant Unobservable Inputs
		Amount				(Level 1)				(Level 2)				(Level 3)
	Assets at December 31:
	Cash and cash equivalents	$	118,616			$	118,616
	Interest-bearing time deposits	47,520				47,520
	Investment securities available for sale	549,543								$	542,897			$	6,646
	Investment securities held to maturity	631,088								614,457				33,266
	Loans held for sale	7,235								7,235
	Loans	3,860,901												3,810,912
	FRB and FHLB stock	41,353								41,353
	Interest rate swap asset	3,867								3,867
	Interest receivable	19,984								19,984
	Liabilities at December 31:
	Deposits	$	4,640,694			$	3,523,199			$	1,099,610
	Borrowings:
	Federal funds purchased	15,381								15,381
	Securities sold under repurchase agreements	124,539								124,539
	FHLB Advances	145,264								146,669
	Subordinated debentures and term loans	126,810								92,802
	Interest rate swap liability	6,537								6,537
	Interest payable	3,201								3,201
		2013
		Carrying				Quoted Prices in Active Markets for Identical Assets				Significant Other Observable Inputs				Significant Unobservable Inputs
		Amount				(Level 1)				(Level 2)				(Level 3)
	Assets at December 31:
	Cash and cash equivalents	$	109,434			$	109,434
	Interest-bearing time deposits	55,069				55,069
	Investment securities available for sale	536,201								$	526,224			$	9,977
	Investment securities held to maturity	559,378								525,998				34,849
	Loans held for sale	5,331								5,331
	Loans	3,564,539												3,506,615
	FRB and FHLB stock	38,990								38,990
	Interest rate swap asset	4,009								4,009
	Interest receivable	18,672								18,672
	Liabilities at December 31:
	Deposits	$	4,231,468			$	3,082,117			$	934,937
	Borrowings:
	Federal funds purchased	125,645								125,645
	Securities sold under repurchase agreements	148,672								148,852
	FHLB Advances	122,140								122,962
	Subordinated debentures and term loans	126,807								82,607
	Interest rate swap liability	3,953								3,953
	Interest payable	1,771								1,771

Commitments_and_Contingent_Lia1

Commitments and Contingent Liabilities (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Schedule of Fair Value, Off-balance Sheet Risks	Financial instruments, whose contract amount represents credit risk as of December 31, were as follows:
		2014		2013
	Amounts of commitments:
	Loan commitments to extend credit	$	1,617,552	$	1,216,470
	Standby letters of credit	$	52,655	$	41,508

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table summarizes the changes in the balances of each component of accumulated other comprehensive income (loss), net of tax, as of December 31, 2014 and 2013:
		Accumulated Other Comprehensive Income (Loss)
		Unrealized Gains (Losses) on Securities Available for Sale			Unrealized Gains (Losses) on Securities Available for Sale for which a Portion of Other-Than-Temporary Impairment has been Recognized in Income			Unrealized Gains (Losses) on Cash Flow Hedges			Unrealized Gains (Losses) on Defined Benefit Plans			Total
	Balance at December 31, 2013	$	1,566		$	(1,847	)	$	(501	)	$	(5,628	)	$	(6,410	)
	Other comprehensive income before reclassifications	14,860			1,847			(2,599		)	(7,580		)	6,528
	Amounts reclassified from accumulated other comprehensive income	(2,328		)				918			(338		)	(1,748		)
	Period change	12,532			1,847			(1,681		)	(7,918		)	4,780
	Balance at December 31, 2014	$	14,098		$	—		$	(2,182	)	$	(13,546	)	$	(1,630	)
	Balance at December 31, 2012	$	17,904		$	(3,272	)	$	(2,652	)	$	(17,479	)	$	(5,499	)
	Other comprehensive income before reclassifications	(16,021		)	1,425			1,543			10,704			(2,349		)
	Amounts reclassified from accumulated other comprehensive income	(317		)				608			1,147			1,438
	Period change	(16,338		)	1,425			2,151			11,851			(911		)
	Balance at December 31, 2013	$	1,566		$	(1,847	)	$	(501	)	$	(5,628	)	$	(6,410	)
Reclassification out of Accumulated Other Comprehensive Income (Loss)	The following table presents the reclassification adjustments out of accumulated other comprehensive income (loss) that were included in net income in the Consolidated Condensed Statements of Income for the twelve months ended December 31, 2014, 2013 and 2012:
		Amount Reclassified from Accumulated Other Comprehensive Income (Loss) For the Year Ended December 31,
	Details about Accumulated Other Comprehensive Income (Loss) Components	2014			2013			2012			Affected Line Item in the Statements of Income
	Unrealized gains (losses) on available for sale securities (1)
	Realized securities gains reclassified into income	$	3,581		$	487		$	2,389		Other income - net realized gains on sales of available for sale securities
	Related income tax expense	(1,253		)	(170		)	(835		)	Income tax expense
		$	2,328		$	317		$	1,554
	Unrealized gains (losses) on cash flow hedges (2)
	Interest rate contracts	$	(1,411	)	$	(935	)	$	(217	)	Interest expense - subordinated debentures and term loans
	Related income tax benefit	493			327			76			Income tax expense
		$	(918	)	$	(608	)	$	(141	)
	Unrealized gains (losses) on defined benefit plans
	Amortization of net loss and prior service costs	$	520		$	(1,765	)	$	100		Other expenses - salaries and employee benefits
	Related income tax benefit (expense)	(182		)	618			(35		)	Income tax expense
		$	338		$	(1,147	)	$	65
	Total reclassifications for the period, net of tax	$	1,748		$	(1,438	)	1,478
	(1) For additional detail related to unrealized gains (losses) on available for sale securities and related amounts reclassified from accumulated other comprehensive income see Note 5. INVESTMENT SECURITIES.
	(2) For additional detail related to unrealized gains (losses) on cash flow hedges and related amounts reclassified from accumulated other comprehensive income see Note 13. DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES.

Regulatory_Capital_Tables

Regulatory Capital (Tables)	12 Months Ended
	Dec. 31, 2014
Banking and Thrift [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations	Actual and required capital amounts and ratios are listed below.
		2014								2013
						Required For								Required For
		Actual				Adequate Capital				Actual				Adequate Capital
	December 31,	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
	Total Capital (to Risk-weighted Assets)
	First Merchants Corporation	$	685,507	15.34	%	$	357,581	8	%	$	599,966	14.54	%	$	330,107	8	%
	First Merchants Bank	653,169		14.64		356,884		8		599,272		14.56		329,344		8
	Tier I Capital (to Risk-weighted Assets)
	First Merchants Corporation	$	564,535	12.63	%	$	178,791	4	%	$	483,186	11.71	%	$	165,053	4	%
	First Merchants Bank	597,305		13.39		178,442		4		547,655		13.3		164,672		4
	Tier I Capital (to Average Assets)
	First Merchants Corporation	$	564,535	10.15	%	$	222,533	4	%	$	483,186	10.2	%	$	189,485	4	%
	First Merchants Bank	597,305		10.56		226,339		4		547,655		11.58		189,095		4

ShareBased_Compensation_Tables

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Assumptions Used In 2012 Black Scholes Model	The estimated fair value of the stock options granted during 2014, 2013, and 2012 was calculated using a Black-Scholes option pricing model.  The following summarizes the assumptions used in the Black-Scholes model:
		2014			2013			2012
	Risk-free interest rate	2.41	%		1.25	%		1.36	%
	Expected price volatility	45.05	%		45.68	%		46.22	%
	Dividend yield	2.73	%		2.96	%		3.29	%
	Forfeiture rate	5.46	%		4.73	%		4.77	%
	Weighted-average expected life, until exercise	7.74		years	7.27		years	7.2		years
Components of Share Based Compensation Awards	The following table summarizes the components of the Corporation's share-based compensation awards recorded as expense:
		Year Ended				Year Ended				Year Ended
		December 31,				December 31,				December 31,
		2014				2013				2012
	Stock and ESPP Options
	Pre-tax compensation expense	$	237			$	253			$	284
	Income tax benefit	(47		)		(16		)		(23		)
	Stock and ESPP option expense, net of income taxes	$	190			$	237			$	261
	Restricted Stock Awards
	Pre-tax compensation expense	$	1,940			$	1,520			$	1,208
	Income tax benefit	(679		)		(531		)		(428		)
	Restricted stock awards expense, net of income taxes	$	1,261			$	989			$	780
	Total Share-Based Compensation:
	Pre-tax compensation expense	$	2,177			$	1,773			$	1,492
	Income tax benefit	(726		)		(547		)		(451		)
	Total share-based compensation expense, net of income taxes	$	1,451			$	1,226			$	1,041
Stock Option Activity Under Stock Option Plans	Stock option activity under the Corporation's stock option plans, as of December 31, 2014, and changes during the year ended December 31, 2014, were as follows:
		Number of			Weighted-Average				Weighted Average		Aggregate
		Shares			Exercise Price				Remaining Contractual		Intrinsic Value
									Term (in Years)
	Outstanding at January 1, 2014	958,786			$	21.32
	Granted	13,500			$	21.65
	Exercised	(41,249	)		$	12.21
	Canceled	(193,106	)		$	24.42
	Outstanding December 31, 2014	737,931			$	20.99			3.08		2,645,356
	Vested and Expected to Vest at December 31, 2014	737,931			$	20.99			3.08		2,645,356
	Exercisable at December 31, 2014	715,431			$	21.05			2.9		2,563,636
Unvested RSAs Outstanding	The following table summarizes information on unvested RSAs outstanding as of December 31, 2014:
		Number of			Weighted-Average
		Shares			Grant Date Fair Value
	Unvested RSAs at January 1, 2014	429,002			$	12.51
	Granted	98,611			$	20.54
	Forfeited	(9,717	)		$	15.78
	Vested	(132,446	)		$	9.16
	Unvested RSAs at December 31, 2014	385,450			$	15.65

Pension_and_Other_Post_Retirem1

Pension and Other Post Retirement Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Schedule of Changes in Benefit Obligation, Changes in Plan Assets and the Funded Status of the Pension Plan and Other Post Retirement Benefit Plans	The table below sets forth the plans’ funded status and amounts recognized in the consolidated balance sheets at December 31, using measurement dates of December 31, 2014 and 2013.
		2014				2013
	Change in Benefit Obligation:
	Benefit obligation at beginning of year	$	62,270			$	69,166
	Service cost	73				131
	Interest cost	3,235				2,670
	Actuarial loss (gain)	12,968				(5,597		)
	Benefits paid	(5,541		)		(4,100		)
	Net transfers in from CFS acquisition	7,645
	Benefit obligation at end of year	$	80,650			$	62,270
	Change in Plan Assets:
	Fair value of plan assets at beginning of year	$	69,871			$	62,865
	Actual return on plan assets	5,232				10,610
	Employer contributions	504				496
	Benefits paid	(5,541		)		(4,100		)
	CFS acquisition	7,073
	End of year	77,139				69,871
	Funded status at end of year	$	(3,511	)		$	7,601
	Assets and Liabilities Recognized in the Balance Sheets:
	Deferred tax asset	$	8,541			$	4,266
	Assets	$	1,329			$	12,383
	Liabilities	$	4,840			$	4,782
	Amounts Recognized in Accumulated Other Comprehensive Income Not Yet Recognized as Components of Net Periodic (Benefit) Cost Consist of:
	Accumulated loss	$	(15,863	)		$	(7,922	)
	Prior service credit	(346		)		(28		)
		$	(16,209	)		$	(7,950	)
Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets	Information for pension plans with an accumulated benefit obligation in excess of plan assets is included in the table below.
		December 31, 2014				December 31, 2013
	Projected benefit obligation	$	4,840			$	4,782
	Accumulated benefit obligation	$	4,840			$	4,782
	Fair value of plan assets
Schedule of Net Periodic Pension Costs	The following table shows the components of net periodic pension costs:
		31-Dec-14				31-Dec-13				31-Dec-12
	Service cost	$	73			$	131			$	161
	Interest cost	3,235				2,670				2,990
	Expected return on plan assets	(4,467		)		(4,265		)		(4,216		)
	Amortization of prior service costs	81				25				25
	Amortization of net loss	478				2,131				2,207
	Net periodic pension (benefit) cost	$	(600	)		$	692			$	1,167
Schedule of Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income, Net of Tax	Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss):
		31-Dec-14				31-Dec-13				31-Dec-12
	Net periodic pension (benefit) cost	$	(600	)		$	692			$	1,167
	Net gain (loss)	(12,203		)		11,942				(1,242		)
	Amortization of loss	478				2,131				2,207
	Amortization of prior service cost	81				25				25
	Total recognized in other comprehensive income (loss)	(11,644		)		14,098				990
	Total recognized in net periodic pension cost and other comprehensive income (loss)	$	(11,044	)		$	13,406			$	(177	)
Schedule of Amounts in Accumulated Other Comprehensive Income (Loss) to be Recognized over Next Fiscal Year	The estimated net loss and transition obligation for the defined benefit pension plans that will be amortized from accumulated other comprehensive income into net periodic pension cost over the next fiscal year are:
		December 31, 2014				December 31, 2013				December 31, 2012
	Amortization of net loss	$	(1,770	)		$	(533	)		$	(2,158	)
	Amortization of prior service cost	(64		)		(25		)		(25		)
	Total	$	(1,834	)		$	(558	)		$	(2,183	)
Schedule of Assumptions Used	Significant assumptions include:
		31-Dec-14			31-Dec-13			December 31, 2012
	Weighted-average Assumptions Used to Determine Benefit Obligation:
	Discount rate	4	%		4.8	%		4	%
	Rate of compensation increase for accruing active participants	3	%		3	%		3	%
	Weighted-average Assumptions Used to Determine Cost:
	Discount rate	4.8	%		4	%		4.5	%
	Expected return on plan assets	6	%		7	%		7	%
	Rate of compensation increase for accruing active participants	3	%		3	%		4	%
Schedule of Expected Benefit Payments	The minimum contribution required in 2015 will likely be zero but the Corporation may decide to make a discretionary contribution during the year.
	2015	$	4,761
	2016	4,757
	2017	4,751
	2018	4,783
	2019	4,997
	After 2019	25,125
		$	49,174
Schedule of Allocation of Plan Assets	Plan assets are re-balanced quarterly. At December 31, 2014 and 2013, plan assets by category are as follows:
		December 31, 2014						December 31, 2013
		Actual			Target			Actual			Target
	Cash and cash equivalents	2.6	%		2	%		2.7	%		2	%
	Equity securities	58.7			60			62.2			60
	Debt securities	36.5			36			33.2			36
	Alternative investments	2.2			2			1.9			2
		100	%		100	%		100	%		100	%
	There are no assets classified within Level 3 of the hierarchy at December 31, 2014 and 2013.
						Fair Value Measurements Using
						Quoted Prices in				Significant Other Observable Inputs			Significant
						Active Markets for							Unobservable
						Identical Assets							Inputs
	December 31, 2014	Fair Value				(Level 1)				(Level 2)			(Level 3)
	Cash & Cash Equivalents	$	2,032			$	2,032
	Corporate Bonds and Notes	9,384				9,384
	Government Agency and Municipal Bonds and Notes	8,252								$	8,252
	Certificates of Deposit	1,001								1,001
	Party-in-Interest Investments
	Common Stock	1,376				1,376
	Common Bond Fund	4,615								4,615
	Common Equity Fund	5,858								5,858
	Mutual Funds
	Taxable Bond	4,987				4,987
	Large Cap Equity	21,185				21,185
	Mid Cap Equity	9,434				9,434
	Small Cap Equity	3,872				3,872
	International Equity	3,474				3,474
	Specialty Alternative Equity	1,669				1,669
		$	77,139			$	57,413			$	19,726		$	—
						Fair Value Measurements Using
						Quoted Prices in				Significant Other Observable Inputs			Significant
						Active Markets for							Unobservable
						Identical Assets							Inputs
	December 31, 2013	Fair Value				(Level 1)				(Level 2)			(Level 3)
	Cash & Cash Equivalents	$	1,864			$	1,864
	Corporate Bonds and Notes	6,076				6,076
	Government Agency and Municipal Bonds and Notes	8,263								$	8,263
	Certificates of Deposit	607								607
	Party-in-Interest Investments
	Common Stock	1,375				1,375
	Common Bond Fund	5,318								5,318
	Common Equity Fund	4,507								4,507
	Mutual Funds
	Taxable Bond	3,901				3,901
	Large Cap Equity	20,617				20,617
	Mid Cap Equity	8,721				8,721
	Small Cap Equity	3,584				3,584
	International Equity	3,727				3,727
	Specialty Alternative Equity	1,311				1,311
		$	69,871			$	51,176			$	18,695		$	—

Income_Tax_Tables

Income Tax (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income tax	The reconciliation between the statutory and actual income tax expense (benefit) is summarized in the following table for the years indicated:
		2014			2013			2012
	Income Tax Expense for the Year Ended December 31:
	Currently Payable:
	Federal	$	(1,661	)	$	738		$	(23	)
	State
	Deferred:
	Federal	22,541			13,939			15,890
	State	510
	Total Income Tax Expense	$	21,390		$	14,677		$	15,867
	Reconciliation of Federal Statutory to Actual Tax Expense:
	Federal Statutory Income Tax at 35%	$	28,543		$	20,722		$	21,347
	Tax-exempt Interest Income	(5,148		)	(3,923		)	(3,716		)
	Stock Compensation	36			50			76
	Earnings on Life Insurance	(1,271		)	(905		)	(1,187		)
	Tax Credits	(911		)	(857		)	(73		)
	Other	141			(410		)	(580		)
	Actual Tax Expense	$	21,390		$	14,677		$	15,867
Deferred Tax Assets and Liabilities	The tax effects of temporary differences related to deferred taxes shown on the balance sheets were:
		2014			2013
	Deferred Tax Asset at December 31:
	Assets:
	Differences in Accounting for Loan Losses	$	26,665		$	28,064
	Differences in Accounting for Loan Fees	747			736
	Differences in Accounting for Loans and Securities	9,910			13,579
	Deferred Compensation	5,234			5,479
	Difference in Accounting for Pensions and Other Employee Benefits	1,084
	Federal & State Income Tax Loss Carryforward and Credits	23,977			24,981
	Net Unrealized Loss on Securities Available for Sale				151
	Other	8,535			12,828
	Total Assets	76,152			85,818
	Liabilities:
	Differences in Depreciation Methods	8,220			8,008
	Difference in Accounting for Pensions and Other Employee Benefits				1,096
	State Income Tax	591			354
	Net Unrealized Gain on Securities Available for Sale	7,591
	Gain on FDIC Modified Whole Bank Transaction	1,694			2,147
	Other	1,096			1,257
	Total Liabilities	19,192			12,862
	Net Deferred Tax Asset Before Valuation Allowance	56,960			72,956
	Valuation allowance:
	Beginning Balance	(17,171		)	(13,859		)
	Decrease/(Increase) During the Year	(397		)	(3,312		)
	Ending Balance	(17,568		)	(17,171		)
	Net Deferred Tax Asset	$	39,392		$	55,785

Net_Income_Per_Share_Tables

Net Income Per Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Net Income Per Share	The following table reconciles basic and diluted net income per share for the years indicated:
		2014					2013						2012
				Weighted-Average Shares						Weighted-Average Shares						Weighted-Average Shares
	Basic net income per share:	$	60,162				$	44,530					$	45,122
	Preferred stock dividends						(2,380		)				(4,539		)
	Net income available to common stockholders	60,162		36,266,356	$	1.66	42,150			29,731,420	$	1.42	40,583			28,632,915	$	1.42
	Effect of dilutive stock options and warrants			288,253						276,960						213,769
	Diluted net income per share:
	Net income available to common stockholders	$	60,162	36,554,609	$	1.65	$	42,150		30,008,380	$	1.41	$	40,583		28,846,684	$	1.41

Quarterly_Results_of_Operation1

Quarterly Results of Operations (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Results of Operations (Unaudited)	The following table sets forth certain quarterly results for the years ended December 31, 2014 and 2013:
		2014								2013
		First		Second		Third		Fourth		First			Second			Third			Fourth
	Interest income	$	51,009	$	51,527	$	53,290	$	53,053	$	43,738		$	40,653		$	40,736		$	45,707
	Interest expense	5,117		5,408		5,424		5,893		4,280			4,003			3,714			4,572
	Net interest income	45,892		46,119		47,866		47,160		39,458			36,650			37,022			41,135
	Provision for loan losses					1,600		960		2,102			1,997			1,533			1,016
	Net interest income after provision for loan losses	45,892		46,119		46,266		46,200		37,356			34,653			35,489			40,119
	Non-interest income	15,186		15,933		18,294		16,254		13,877			14,059			11,800			15,073
	Non-interest expense	43,089		41,250		42,576		41,677		34,700			33,742			34,219			40,558
	Income before income tax expense	17,989		20,802		21,984		20,777		16,533			14,970			13,070			14,634
	Income tax expense	4,369		5,642		5,862		5,517		4,668			4,155			2,667			3,187
	Net income	13,620		15,160		16,122		15,260		11,865			10,815			10,403			11,447
	Preferred stock dividends									(857		)	(852		)	(430		)	(241		)
	Net income available to common stockholders	$	13,620	$	15,160	$	16,122	$	15,260	$	11,008		$	9,963		$	9,973		$	11,206
	Basic EPS	$	0.38	$	0.42	$	0.45	$	0.41	$	0.38		$	0.35		$	0.35		$	0.34
	Diluted EPS	$	0.38	$	0.41	$	0.45	$	0.41	$	0.38		$	0.34		$	0.35		$	0.34
	Average Shares Outstanding:
	Basic	35,956,436		36,026,763		36,054,867		37,018,014		28,716,987			28,783,407			28,806,809			32,597,145
	Diluted	36,260,624		36,294,149		36,328,981		37,323,276		28,971,238			29,023,513			29,081,472			32,912,605

Condensed_Financial_Informatio1

Condensed Financial Information (parent company only) (Tables)	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule Of Parent Company Information Balance Sheet	Condensed Balance Sheets
		31-Dec-14			31-Dec-13
	Assets
	Cash	$	36,044		$	13,228
	Investment in subsidiaries	820,123			745,818
	Goodwill	448			448
	Other assets	6,281			8,695
	Total assets	$	862,896		$	768,189
	Liabilities
	Borrowings	$	126,702		$	126,702
	Other liabilities	9,367			6,564
	Total liabilities	136,069			133,266
	Stockholders' equity	726,827			634,923
	Total liabilities and stockholders' equity	$	862,896		$	768,189
Schedule Of Parent Company Information Income Statement	Condensed Statements of Income and Comprehensive Income
		December 31, 2014			December 31, 2013			December 31, 2012
	Income
	Dividends from subsidiaries	$	53,231		$	63,732		$	30,096
	Other income	538			45			85
	Total income	53,769			63,777			30,181
	Expenses
	Interest expense	6,616			3,531			4,655
	Salaries and employee benefits	3,128			3,284			3,194
	Net occupancy and equipment expenses	442			258			312
	Telephone expenses	27			42			30
	Postage and courier expenses							1
	Other expenses	1,972			2,617			1,502
	Total expenses	12,185			9,732			9,694
	Income before income tax benefit and equity in undistributed income of subsidiaries	41,584			54,045			20,487
	Income tax benefit	3,999			3,153			3,316
	Income before equity in undistributed income of subsidiaries	45,583			57,198			23,803
	Equity in undistributed (distributions in excess of) income of subsidiaries	14,579			(12,668		)	21,319
	Net income	60,162			44,530			45,122
	Preferred stock dividends and discount accretion				(2,380		)	(4,539		)
	Net income available to common stockholders	$	60,162		$	42,150		$	40,583
	Net income	$	60,162		$	44,530		$	45,122
	Other comprehensive income (loss)	4,780			(911		)	(1,897		)
	Comprehensive income	$	64,942		$	43,619		$	43,225
Schedule Of Parent Company Information Cash Flow	Condensed Statement of Cash Flows
		Year Ended December 31,
		2014			2013			2012
	Cash Flow From Operating Activities:
	Net income	$	60,162		$	44,530		$	45,122
	Adjustments to Reconcile Net Income to Net Cash:
	Share-based compensation	887			778			632
	Distributions in excess of (equity in undistributed) income of subsidiaries	(14,579		)	12,668			(21,319		)
	Net Change in:
	Other assets	2,425			(1,354		)	1,902
	Other liabilities	1,466			(8,438		)	1,122
	Investment in subsidiaries - operating activities	(4,517		)	12,991			(1,755		)
	Net cash provided by operating activities	$	45,844		$	61,175		$	25,704
	Cash Flow From Investing Activities:
	Investment in subsidiaries							$	(126	)
	Net cash paid in acquisition	$	(12,832	)
	Other				$	240
	Net cash provided (used) in investing activities	$	(12,832	)	$	240		$	(126	)
	Cash Flow From Financing Activities:
	Cash dividends	$	(10,694	)	$	(7,992	)	$	(7,442	)
	Repayment of borrowings				(55,000		)	(4,124		)
	Proceeds from issuance of long-term debt				70,000
	Preferred stock redemption under small business lending fund				(90,783		)
	Stock issued under employee benefit plans	478			479			449
	Stock issued under dividend reinvestment and stock purchase plan	523			325			202
	Stock options exercised	564			115			78
	Stock redeemed	(1,067		)	(491		)	(235		)
	Net cash used by financing activities	$	(10,196	)	$	(83,347	)	$	(11,072	)
	Net change in cash	22,816			(21,932		)	14,506
	Cash, beginning of the year	13,228			35,160			20,654
	Cash, end of year	$	36,044		$	13,228		$	35,160

Nature_of_Operations_and_Summa1

Nature of Operations and Summary of Significant Accounting Policies - Allowance for Loan Losses (Details)	12 Months Ended
	Dec. 31, 2014
	key_element
Accounting Policies [Abstract]
Number of key element used in assessing the appropriateness of the allowance for loan losses	3

Nature_of_Operations_and_Summa2

Nature of Operations and Summary of Significant Accounting Policies - Premises and Equipment (Details)	12 Months Ended
	Dec. 31, 2014
Minimum
Premises and Equipment [Line Items]
Estimated useful lives of assets	3 years
Maximum
Premises and Equipment [Line Items]
Estimated useful lives of assets	40 years

Nature_of_Operations_and_Summa3

Nature of Operations and Summary of Significant Accounting Policies - Intangible Assets (Details)	12 Months Ended
	Dec. 31, 2014
Minimum
Intangible Assets [Abstract]
Estimated useful lives of intangible assets	3 years
Maximum
Intangible Assets [Abstract]
Estimated useful lives of intangible assets	20 years

Nature_of_Operations_and_Summa4

Nature of Operations and Summary of Significant Accounting Policies - Requisite Service Period, Stock Award Plans (Details)	12 Months Ended
	Dec. 31, 2014
Minimum
Schedule of Stock Options and Restricted Stock Award Plans [Line Items]
Requisite service period	2 years
Maximum
Schedule of Stock Options and Restricted Stock Award Plans [Line Items]
Requisite service period	3 years

Purchase_and_Assumption_Narrat

Purchase and Assumption - Narrative (Detail) (USD $)	Feb. 10, 2012
Business Acquisition [Line Items]
Assets acquired	$147,700,000
Cash and cash equivalents	11,900,000
Marketable securities	18,900,000
Federal Home Loan Bank stock	1,800,000
Loans	113,000,000
Premises and equipment	2,100,000
Liabilities absorbed	135,700,000
Customer deposits	125,900,000
Other borrowed money	9,600,000
Other liabilities	402,000
Assets acquired, discount	29,000,000
Difference between the purchase price of the assets acquired and the value of the liabilities assumed	17,200,000
Loans Receivable
Business Acquisition [Line Items]
Loans	86,300,000
Loan portfolio acquired, fair value discount	19,200,000
Performing portion of loan portfolio, fair value	$76,500,000

Purchase_and_Assumption_Assets

Purchase and Assumption - Assets and Liabilities of SCB Recorded at Provisional Fair Value (Detail) (USD $)	12 Months Ended		0 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Feb. 10, 2012
Assets
Investment securities, available for sale			$18,900
Federal Home Loan Bank stock			1,800
Loans:
Total Assets Purchased			147,700
Deposits:
Total Liabilities Assumed			135,700
Net Gain on Acquisition		9,124
Cash received from FDIC			17,200
SCB Bank
Assets
Cash and due from banks			29,113
Investment securities, available for sale			18,896
Federal Home Loan Bank stock			1,761
Loans:
Total Loans			93,793
Premises			1,516
Core deposit intangible			484
Other assets			560
Total Assets Purchased			146,123
Deposits:
Total Deposits			125,909
Federal Home Loan Bank advances			10,286
Other liabilities			804
Total Liabilities Assumed			136,999
Net Gain on Acquisition			9,124
SCB Bank | Non-interest bearing
Deposits:
Total Deposits			13,715
SCB Bank | NOW accounts
Deposits:
Total Deposits			14,746
SCB Bank | Savings and money market
Deposits:
Total Deposits			25,843
SCB Bank | Certificate of deposit
Deposits:
Total Deposits			71,605
SCB Bank | Commercial
Loans:
Total Loans			51,042
SCB Bank | Residential mortgage
Loans:
Total Loans			11,181
SCB Bank | Installment
Loans:
Total Loans			$31,570

Purchase_and_Assumption_Acquir

Purchase and Assumption - Acquired Loans Accounted With ASC 310 30 (Detail) (USD $)	Feb. 10, 2012
In Thousands, unless otherwise specified
Business Combinations [Abstract]
Preliminary estimate of contractually required principal and interest at acquisition	$31,143
Preliminary estimate of contractual cash flows not expected to be collected (nonaccretable differences)	9,688
Preliminary estimate of expected cash flows at acquisition	21,455
Preliminary estimate of interest component of expected cash flows (accretable discount)	4,152
Preliminary estimate of fair value of acquired loans accounted for under ASC 310-30	$17,303

Business_Combination_Narrative

Business Combination - Narrative (Details) (USD $)	12 Months Ended		0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Nov. 07, 2014	Nov. 12, 2013
			bank_branch	bank_branch
Business Acquisition [Line Items]
Value of stock issued as a part of acquisition	$34,981,000	$135,642,000
Common Stock
Business Acquisition [Line Items]
Stock issued as a part of acquisition (in shares)	1,574,298	7,079,457
Value of stock issued as a part of acquisition	197,000	885,000
Merger with Community Bancshares, Inc.
Business Acquisition [Line Items]
Percentage of interest acquired			100.00%
Number of banking centers acquired			10
Number of shares of common stock			4.0926
Share price			$85.94
Cash paid in acquisition			14,200,000
Stock issued as a part of acquisition (in shares)			1,600,000
Value of stock issued as a part of acquisition			35,000,000
Total purchase price			49,189,000
Core deposit intangible			4,658,000
Acquired intangible asset, expected useful life			10 years
Pro forma revenue	1,600,000
Pro forma nonrecurring expense	1,800,000
Merger with Community Bancshares, Inc. | Common Stock
Business Acquisition [Line Items]
Number of shares of common stock			4.0926
Merger with CFS Bancorp, Inc. (Citizens)
Business Acquisition [Line Items]
Percentage of interest acquired				100.00%
Number of banking centers acquired				20
Stock issued as a part of acquisition (in shares)				7,100,000
Value of stock issued as a part of acquisition				135,600,000
Total purchase price				135,642,000
Core deposit intangible				7,313,000
Acquired intangible asset, expected useful life				10 years
Pro forma revenue		4,900,000
Pro forma nonrecurring expense		$9,500,000
Merger with CFS Bancorp, Inc. (Citizens) | CFS Bancorp
Business Acquisition [Line Items]
Percentage of common stock received per shares owned through acquisition				0.65%

Business_Combination_Assets_Ac

Business Combination - Assets Acquired and Liabilities Assumed (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 10, 2012	Nov. 07, 2014	Nov. 12, 2013
In Thousands, unless otherwise specified
Business Acquisition [Line Items]
Cash and cash equivalents				$11,900
Investment securities				18,900
Premises and equipment				2,100
Goodwill	202,724	188,948	141,375
Merger with Community Bancshares, Inc.
Business Acquisition [Line Items]
Cash and cash equivalents					4,124
Interest-bearing time deposits					16,526
Loans					145,064
Premises and equipment					3,610
Federal Home Loan Bank stock					1,950
Interest receivable					767
Cash surrender value of life insurance					3,266
Other real estate owned					6,662
Tax asset, deferred and receivable					3,348
Other assets					167
Deposits					-228,424
Interest payable					-98
Other liabilities					-3,014
Net tangible assets acquired					30,755
Core deposit intangible					4,658
Goodwill					13,776
Purchase price					49,189
Merger with Community Bancshares, Inc. | Available for Sale Securities
Business Acquisition [Line Items]
Investment securities					76,807
Merger with CFS Bancorp, Inc. (Citizens)
Business Acquisition [Line Items]
Cash and cash equivalents						10,992
Interest-bearing time deposits						213,379
Mortgage loans held for sale						189
Loans						603,114
Premises and equipment						19,643
Federal Home Loan Bank stock						6,188
Interest receivable						1,770
Cash surrender value of life insurance						36,555
Other real estate owned						12,857
Tax asset, deferred and receivable						30,717
Other assets						111,656
Deposits						-955,432
Securities sold under repurchase agreements						-9,830
Federal Home Loan Bank advances						-15,000
Interest payable						-294
Other liabilities						-16,033
Net tangible assets acquired						80,756
Core deposit intangible						7,313
Goodwill						47,573
Purchase price						135,642
Merger with CFS Bancorp, Inc. (Citizens) | Available for Sale Securities
Business Acquisition [Line Items]
Investment securities						15,913
Merger with CFS Bancorp, Inc. (Citizens) | Held to Maturity Securities
Business Acquisition [Line Items]
Investment securities						$14,372

Business_Combination_Pro_Forma

Business Combination - Pro Forma Information (Details) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Total revenue (net interest income plus other income)	$263,070	$253,668	$266,034
Net income	61,572	39,979	50,092
Net income available to common shareholders	$61,572	$37,599	$45,553
Earnings per share:
Basic	$1.63	$0.98	$1.28
Diluted	$1.61	$0.97	$1.27

Restriction_on_Cash_and_Due_Fr1

Restriction on Cash and Due From Banks (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Restricted Cash and Cash Equivalents Items [Line Items]
Cash balance, Federal Home Loan Bank And Federal Reserve Bank	$13,910
Cash reserve with Federal Reserve Bank	22,595
Interest-bearing Deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Cash amount that exceeded federally insured limits	$103,154

Investment_Securities_Amortize

Investment Securities - Amortized Cost and Approximate Fair Values of Securities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Gain (Loss) on Investments [Line Items]
Amortized Cost	$529,212	$537,848
Gross Unrealized Gains	20,581	7,896
Gross Unrealized Losses	250	9,543
Investment securities available for sale	549,543	536,201
Amortized Cost	631,088	559,378
Gross Unrealized Gains	17,243	5,282
Gross Unrealized Losses	608	3,813
Fair Value	647,723	560,847
Amortized Cost	1,160,300	1,097,226
Gross Unrealized Gains	37,824	13,178
Gross Unrealized Losses	858	13,356
Fair Value	1,197,266	1,097,048
U.S. Treasury
Gain (Loss) on Investments [Line Items]
Amortized Cost		15,914
Gross Unrealized Gains		80
Gross Unrealized Losses		21
Investment securities available for sale		15,973
Government Agency and Municipal Bonds and Notes
Gain (Loss) on Investments [Line Items]
Amortized Cost	100	3,550
Gross Unrealized Gains	9	12
Gross Unrealized Losses		17
Investment securities available for sale	109	3,545
State and municipal
Gain (Loss) on Investments [Line Items]
Amortized Cost	216,915	231,005
Gross Unrealized Gains	11,801	3,878
Gross Unrealized Losses	123	3,896
Investment securities available for sale	228,593	230,987
Amortized Cost	204,443	145,941
Gross Unrealized Gains	5,716	62
Gross Unrealized Losses	96	91
Fair Value	210,063	145,912
U.S. Government-sponsored mortgage-backed securities
Gain (Loss) on Investments [Line Items]
Amortized Cost	310,460	279,299
Gross Unrealized Gains	8,771	3,926
Gross Unrealized Losses	127	1,973
Investment securities available for sale	319,104	281,252
Amortized Cost	426,645	413,437
Gross Unrealized Gains	11,527	5,220
Gross Unrealized Losses	512	3,722
Fair Value	437,660	414,935
Corporate obligations
Gain (Loss) on Investments [Line Items]
Amortized Cost	31	6,374
Gross Unrealized Losses		3,636
Investment securities available for sale	31	2,738
Equity securities
Gain (Loss) on Investments [Line Items]
Amortized Cost	1,706	1,706
Investment securities available for sale	$1,706	$1,706

Investment_Securities_Narrativ

Investment Securities - Narrative (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2009
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Fair value	$72,390,000	$477,132,000
Gross Unrealized Losses	250,000	9,543,000
Gross Unrealized Losses	608,000	3,813,000
Amortized Cost	529,212,000	537,848,000
Carrying value of securities pledged as collateral	449,408,000	373,533,000	345,866,000
Gross gains on securities sold	3,581,000	487,000	2,389,000
Gross losses	0	0	0
Gross Unrealized Losses	250,000	9,543,000
Corporate obligations
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Amortized Cost		6,400,000
Gross gains on securities sold	1,900,000
Gross Unrealized Losses		3,636,000
Accumulated OTTI on securities	9,400,000
Net impairment losses recognized in earnings				500,000
Investments in Debt and Equity Securities, Reported at Less than Historical Cost
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Historical cost	73,249,000	490,488,000
Fair value	72,390,000	477,132,000
Percent of the Corporation's available for sale and held to maturity portfolio	6.10%	43.60%
U.S. Treasury Securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross Unrealized Losses		21,000
Amortized Cost		15,914,000
U.S. Government-sponsored agency securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross Unrealized Losses		17,000
Amortized Cost	100,000	3,550,000
U.S. Government-sponsored mortgage-backed securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross Unrealized Losses	127,000	1,973,000
Available-for-sale, number of securities in unrealized loss positions	4
Gross Unrealized Losses	512,000	3,722,000
Held-to-maturity, number of securities in unrealized loss positions	13
Amortized Cost	310,460,000	279,299,000
State and municipal
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross Unrealized Losses	123,000	3,896,000
Available-for-sale, number of securities in unrealized loss positions	22
Gross Unrealized Losses	96,000	91,000
Held-to-maturity, number of securities in unrealized loss positions	16
Amortized Cost	216,915,000	231,005,000
Corporate obligations
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross Unrealized Losses		3,636,000
Amortized Cost	$31,000	$6,374,000

Investment_Securities_Debt_Sec

Investment Securities - Debt Securities Credit Loss Recognized in Income, and Other Losses Recorded in Other Comprehensive Income (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Credit losses on debt securities held:
Balance, January 1	$11,355	$11,355
Reductions for previous other-than-temporary losses realized on securities sold during the year	-10,855
Balance, December 31	$500	$11,355

Investment_Securities_Investme

Investment Securities - Investments' Gross Unrealized Losses and Fair Value Aggregated by Investment Category and Length of Time in Continuous Unrealized Loss Position (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	$3,442	$237,965
Less than 12 Months, Unrealized Losses	20	5,579
12 Months or Longer, Fair Value	15,297	5,977
12 Months or Longer, Unrealized Losses	230	3,964
Total, Fair Value	18,739	243,942
Total, Gross Unrealized Losses	250	9,543
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	14,910	230,366
Less than 12 Months, Gross Unrealized Losses	178	3,553
12 Months or Longer, Fair Value	38,741	2,824
12 Months or Longer, Gross Unrealized Losses	430	260
Total, Fair Value	53,651	233,190
Total, Gross Unrealized Losses	608	3,813
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Less than 12 Months, Fair Value	18,352	468,331
Less than 12 Months, Gross Unrealized Losses	198	9,132
12 Months or Longer, Fair Value	54,038	8,801
12 Months or Longer, Gross Unrealized Losses	660	4,224
Total, Fair Value	72,390	477,132
Total, Gross Unrealized Losses	858	13,356
State and municipal
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	5,119	17,318
Less than 12 Months, Gross Unrealized Losses	96	91
12 Months or Longer, Fair Value	250	184
Total, Fair Value	5,369	17,502
Total, Gross Unrealized Losses	96	91
U.S. Government-sponsored mortgage-backed securities
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	9,791	213,048
Less than 12 Months, Gross Unrealized Losses	82	3,462
12 Months or Longer, Fair Value	38,491	2,640
12 Months or Longer, Gross Unrealized Losses	430	260
Total, Fair Value	48,282	215,688
Total, Gross Unrealized Losses	512	3,722
U.S. Treasury
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value		4,875
Less than 12 Months, Unrealized Losses		21
12 Months or Longer, Fair Value
12 Months or Longer, Unrealized Losses
Total, Fair Value		4,875
Total, Gross Unrealized Losses		21
Government Agency and Municipal Bonds and Notes
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value		3,433
Less than 12 Months, Unrealized Losses		17
12 Months or Longer, Fair Value
12 Months or Longer, Unrealized Losses
Total, Fair Value		3,433
Total, Gross Unrealized Losses		17
State and municipal
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	1,256	111,791
Less than 12 Months, Unrealized Losses	7	3,840
12 Months or Longer, Fair Value	9,850	583
12 Months or Longer, Unrealized Losses	116	56
Total, Fair Value	11,106	112,374
Total, Gross Unrealized Losses	123	3,896
U.S. Government-sponsored mortgage-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	2,186	117,866
Less than 12 Months, Unrealized Losses	13	1,701
12 Months or Longer, Fair Value	5,447	2,683
12 Months or Longer, Unrealized Losses	114	272
Total, Fair Value	7,633	120,549
Total, Gross Unrealized Losses	127	1,973
Corporate obligations
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
12 Months or Longer, Fair Value		2,711
12 Months or Longer, Unrealized Losses		3,636
Total, Fair Value		2,711
Total, Gross Unrealized Losses		$3,636

Investment_Securities_Amortize1

Investment Securities - Amortized Cost and Fair Value of Available for Sale Securities and Held to Maturity Securities by Contractual Maturity (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Due in one year or less	$3,127
Due after one through five years	9,565
Due after five through ten years	48,675
Due after ten years	155,679
Available-For-Sale Securities, Debt Maturity, with Single Maturity Date, Amortized Cost, Total	217,046
Total Investment Securities	529,212
Due in one year or less	3,153
Due after one through five years	9,840
Due after five through ten years	50,889
Due after ten years	164,851
Available-For-Sale Securities, Debt Maturity, with Single Maturity Date, Fair Value, Total	228,733
Total Investment Securities	549,543
Due in one year or less	6,258
Due after one through five years	18,440
Due after five through ten years	85,997
Due after ten years	93,748
Held-To-Maturity Securities, Debt Maturities, with Single Maturity Date, Net Carrying Amount, Total	204,443
Amortized Cost	631,088	559,378
Due in one year or less	6,329
Due after one through five years	18,930
Due after five through ten years	87,903
Due after ten years	96,901
Held-To-Maturity Securities, Debt Maturity, with Single Maturity Date, Fair Value, Total	210,063
Fair Value	647,723	560,847
U.S. Government-sponsored mortgage-backed securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Without single maturity date	310,460
Without single maturity date	319,104
Amortized Cost	426,645	413,437
Fair Value	437,660	414,935
Equity securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Without single maturity date	1,706
Without single maturity date	$1,706

Loans_and_Allowance_Narrative_

Loans and Allowance - Narrative (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale	$7,235				$5,331				$7,235	$5,331
Allowance for loan losses	63,964				67,870				63,964	67,870	69,366	70,898
Decrease in allowance for loan losses									3,906
Increase in reserve on impaired loans									1,186
Reserve on impaired loans	2,769				1,583				2,769	1,583	4,243
Net charge offs									6,466
Decrease in net charge offs									1,678
Provision for loan losses	960	1,600			1,016	1,533	1,997	2,102	2,560	6,648	18,534
Decrease in provision for loan losses									4,088
Commercial impaired loan total	116,223				119,755				116,223	119,755	79,179
Merger with Community Bancshares, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial impaired loan total	17,027								17,027
Merger with CFS Bancorp, Inc. (Citizens)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial impaired loan total					69,448					69,448
SCB Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial impaired loan total											17,334
Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reserve on impaired loans	1,120				6				1,120	6	2,460
Percentage of troubled debt restructured loans									49.00%
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	13,152				15,077				13,152	15,077	14,157	12,343
Reserve on impaired loans	194								194		50
Provision for loan losses									($839)	$3,514	$6,176
Percentage of troubled debt restructured loans									28.00%

Loans_and_Allowance_Compositio

Loans and Allowance - Composition of Loan Portfolio by Loan Class (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Loans:
Loans	$3,924,865	$3,632,409
Allowance for loan losses	-63,964	-67,870	-69,366	-70,898
Net loans	3,860,901	3,564,539
Commercial and industrial loans
Loans:
Loans	896,688	761,705
Agricultural production financing and other loans to farmers
Loans:
Loans	104,927	114,348
Construction
Loans:
Loans	207,221	177,082
Commercial and farmland
Loans:
Loans	1,672,661	1,611,809
Residential
Loans:
Loans	647,315	616,385
Allowance for loan losses	-13,152	-15,077	-14,157	-12,343
Home equity
Loans:
Loans	286,529	255,223
Individuals' loans for household and other personal expenditures
Loans:
Loans	73,400	69,783
Allowance for loan losses	-2,658	-2,515	-2,593	-2,902
Lease financing receivables, net of unearned income
Loans:
Loans	1,106	1,545
Allowance for loan losses	-3			-3
Other loans
Loans:
Loans	$35,018	$24,529

Loans_and_Allowance_Changes_in

Loans and Allowance - Changes in Allowance for Loan Losses by Loan Segment (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for loan losses:
Beginning balance				$67,870				$69,366	$67,870	$69,366	$70,898
Provision for losses	960	1,600			1,016	1,533	1,997	2,102	2,560	6,648	18,534
Recoveries on loans									10,916	9,990	7,206
Loans charged off									-17,382	-18,134	-27,272
Ending balance	63,964				67,870				63,964	67,870	69,366
Commercial
Allowance for loan losses:
Beginning balance				27,176				25,913	27,176	25,913	17,731
Provision for losses									3,459	2,794	14,749
Recoveries on loans									5,435	4,586	1,744
Loans charged off									-7,246	-6,117	-8,311
Ending balance	28,824				27,176				28,824	27,176	25,913
Commercial Real Estate
Allowance for loan losses:
Beginning balance				23,102				26,703	23,102	26,703	37,919
Provision for losses									-464	340	-2,546
Recoveries on loans									3,297	3,552	3,652
Loans charged off									-6,608	-7,493	-12,322
Ending balance	19,327				23,102				19,327	23,102	26,703
Consumer
Allowance for loan losses:
Beginning balance				2,515				2,593	2,515	2,593	2,902
Provision for losses									423	-11	126
Recoveries on loans									377	556	695
Loans charged off									-657	-623	-1,130
Ending balance	2,658				2,515				2,658	2,515	2,593
Residential
Allowance for loan losses:
Beginning balance				15,077				14,157	15,077	14,157	12,343
Provision for losses									-839	3,514	6,176
Recoveries on loans									1,783	1,292	1,113
Loans charged off									-2,869	-3,886	-5,475
Ending balance	13,152				15,077				13,152	15,077	14,157
Finance Leases
Allowance for loan losses:
Beginning balance											3
Provision for losses									-19	11	29
Recoveries on loans									24	4	2
Loans charged off									-2	-15	-34
Ending balance	$3								$3

Loans_and_Allowance_Allowance_

Loans and Allowance - Allowance for Credit Losses and Loan Portfolio by Loan Segment (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment	$2,119	$1,354
Allowance balances - Collectively evaluated for impairment	61,195	66,287
Allowance balances - Loans Acquired with Deteriorated Credit Quality	650	229
Total Allowance for Loan Losses	63,964	67,870	69,366	70,898
Loan balances - Individually evaluated for impairment	44,093	42,067
Loan balances - Collectively evaluated for impairment	3,807,707	3,511,501
Loan balances - Loans Acquired with Deteriorated Credit Quality	73,065	78,841
Loans	3,924,865	3,632,409
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment	1,455	585
Allowance balances - Collectively evaluated for impairment	27,369	26,493
Allowance balances - Loans Acquired with Deteriorated Credit Quality		98
Total Allowance for Loan Losses	28,824	27,176	25,913	17,731
Loan balances - Individually evaluated for impairment	16,108	10,240
Loan balances - Collectively evaluated for impairment	1,011,122	882,794
Loan balances - Loans Acquired with Deteriorated Credit Quality	9,403	7,548
Loans	1,036,633	900,582
Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment	470	763
Allowance balances - Collectively evaluated for impairment	18,207	22,208
Allowance balances - Loans Acquired with Deteriorated Credit Quality	650	131
Total Allowance for Loan Losses	19,327	23,102	26,703	37,919
Loan balances - Individually evaluated for impairment	23,963	29,007
Loan balances - Collectively evaluated for impairment	1,796,797	1,690,285
Loan balances - Loans Acquired with Deteriorated Credit Quality	59,122	69,599
Loans	1,879,882	1,788,891
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Collectively evaluated for impairment	2,658	2,515
Total Allowance for Loan Losses	2,658	2,515	2,593	2,902
Loan balances - Collectively evaluated for impairment	73,400	69,783
Loans	73,400	69,783
Residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment	194	6
Allowance balances - Collectively evaluated for impairment	12,958	15,071
Total Allowance for Loan Losses	13,152	15,077	14,157	12,343
Loan balances - Individually evaluated for impairment	4,022	2,820
Loan balances - Collectively evaluated for impairment	925,282	867,094
Loan balances - Loans Acquired with Deteriorated Credit Quality	4,540	1,694
Loans	933,844	871,608
Finance Leases
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Collectively evaluated for impairment	3
Total Allowance for Loan Losses	3			3
Loan balances - Collectively evaluated for impairment	1,106	1,545
Loans	$1,106	$1,545

Loans_and_Allowance_Summary_of

Loans and Allowance - Summary of Non-Accrual Loans by Loan Class (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$48,789	$56,402
Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	7,048	9,283
Agriculture production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	5,800	30
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,439	4,978
Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	19,350	28,095
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	12,933	12,068
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,988	1,667
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	231	117
Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans		$164

Loans_and_Allowance_Compositio1

Loans and Allowance - Composition of Impaired Loans by Loan Class (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	$158,563	$189,779	$109,594
Recorded Investment	102,793	114,253	67,333
Average Recorded Investment	106,807	119,561	76,517
Interest Income Recognized	4,297	2,048	1,498
Unpaid Principal Balance	16,703	6,121	12,918
Recorded Investment	13,430	5,502	11,846
Related Allowance	2,769	1,583	4,243
Average Recorded Investment	15,764	5,607	12,097
Interest Income Recognized	65	18	203
Impaired Financing Receivable, Unpaid Principal Balance	175,266	195,900	122,512
Impaired Financing Receivable, Recorded Investment	116,223	119,755	79,179
Average Recorded Investment	122,571	125,168	88,614
Interest Income Recognized	4,362	2,066	1,701
Commercial and industrial loans
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	35,514	35,066	28,532
Recorded Investment	18,029	16,371	11,730
Average Recorded Investment	18,711	19,209	15,089
Interest Income Recognized	362	192	124
Unpaid Principal Balance	1,766	1,390	4,415
Recorded Investment	1,684	1,216	4,155
Related Allowance	1,055	683	1,628
Average Recorded Investment	1,721	1,240	4,225
Interest Income Recognized	40	9	33
Agriculture production financing and other loans to farmers
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	26	32
Recorded Investment	22	30
Average Recorded Investment	26	32
Unpaid Principal Balance	6,777
Recorded Investment	5,777
Related Allowance	400
Average Recorded Investment	8,044
Interest Income Recognized	1
Construction
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	12,956	16,109	9,787
Recorded Investment	9,318	10,625	5,164
Average Recorded Investment	9,837	11,621	6,471
Interest Income Recognized	427	117	66
Unpaid Principal Balance		4,657	1,202
Recorded Investment		4,215	1,058
Related Allowance		894	105
Average Recorded Investment		4,291	1,175
Interest Income Recognized		9
Commercial and farmland
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	95,856	128,073	58,173
Recorded Investment	68,187	83,033	43,204
Average Recorded Investment	70,844	84,057	46,788
Interest Income Recognized	3,389	1,663	1,211
Unpaid Principal Balance	7,159	74	5,579
Recorded Investment	4,971	71	5,182
Related Allowance	1,120	6	2,460
Average Recorded Investment	4,999	76	5,239
Interest Income Recognized	24		95
Residential
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	10,591	6,746	8,820
Recorded Investment	6,839	3,910	6,215
Average Recorded Investment	6,987	4,236	7,129
Interest Income Recognized	119	75	83
Unpaid Principal Balance	1,001		1,722
Recorded Investment	998		1,451
Related Allowance	194		50
Average Recorded Investment	1,000		1,458
Interest Income Recognized			75
Home equity
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	3,590	3,299	4,199
Recorded Investment	398	112	1,006
Average Recorded Investment	402	225	1,022
Interest Income Recognized			13
Other loans
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance	30	454	83
Recorded Investment		172	14
Average Recorded Investment		181	18
Interest Income Recognized		$1	$1

Loans_and_Allowance_Credit_Qua

Loans and Allowance - Credit Quality of Loan Portfolio by Loan Class (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment [Line Items]
Loans	$3,924,865	$3,632,409
Commercial and industrial loans
Financing Receivable, Recorded Investment [Line Items]
Loans	896,688	761,705
Agricultural production financing and other loans to farmers
Financing Receivable, Recorded Investment [Line Items]
Loans	104,927	114,348
Construction
Financing Receivable, Recorded Investment [Line Items]
Loans	207,221	177,082
Commercial and farmland
Financing Receivable, Recorded Investment [Line Items]
Loans	1,672,661	1,611,809
Residential
Financing Receivable, Recorded Investment [Line Items]
Loans	647,315	616,385
Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	286,529	255,223
Consumer
Financing Receivable, Recorded Investment [Line Items]
Loans	73,400	69,783
Finance Leases
Financing Receivable, Recorded Investment [Line Items]
Loans	1,106	1,545
Other loans
Financing Receivable, Recorded Investment [Line Items]
Loans	35,018	24,529
Commercial Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	2,849,876	2,635,448
Commercial Pass | Commercial and industrial loans
Financing Receivable, Recorded Investment [Line Items]
Loans	823,732	708,835
Commercial Pass | Agricultural production financing and other loans to farmers
Financing Receivable, Recorded Investment [Line Items]
Loans	96,155	114,318
Commercial Pass | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans	185,394	162,976
Commercial Pass | Commercial and farmland
Financing Receivable, Recorded Investment [Line Items]
Loans	1,552,781	1,473,714
Commercial Pass | Residential
Financing Receivable, Recorded Investment [Line Items]
Loans	149,430	143,657
Commercial Pass | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	6,368	6,194
Commercial Pass | Finance Leases
Financing Receivable, Recorded Investment [Line Items]
Loans	998	1,420
Commercial Pass | Other loans
Financing Receivable, Recorded Investment [Line Items]
Loans	35,018	24,334
Commercial Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	64,631	72,407
Commercial Special Mention | Commercial and industrial loans
Financing Receivable, Recorded Investment [Line Items]
Loans	24,455	11,332
Commercial Special Mention | Agricultural production financing and other loans to farmers
Financing Receivable, Recorded Investment [Line Items]
Loans	1,195
Commercial Special Mention | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans	3,164	1,132
Commercial Special Mention | Commercial and farmland
Financing Receivable, Recorded Investment [Line Items]
Loans	29,484	57,676
Commercial Special Mention | Residential
Financing Receivable, Recorded Investment [Line Items]
Loans	6,321	2,232
Commercial Special Mention | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	12	35
Commercial Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	160,608	146,254
Commercial Substandard | Commercial and industrial loans
Financing Receivable, Recorded Investment [Line Items]
Loans	48,226	41,013
Commercial Substandard | Agricultural production financing and other loans to farmers
Financing Receivable, Recorded Investment [Line Items]
Loans	7,577	30
Commercial Substandard | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans	2,928	12,029
Commercial Substandard | Commercial and farmland
Financing Receivable, Recorded Investment [Line Items]
Loans	90,161	80,184
Commercial Substandard | Residential
Financing Receivable, Recorded Investment [Line Items]
Loans	10,918	11,494
Commercial Substandard | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	690	1,184
Commercial Substandard | Finance Leases
Financing Receivable, Recorded Investment [Line Items]
Loans	108	125
Commercial Substandard | Other loans
Financing Receivable, Recorded Investment [Line Items]
Loans		195
Commercial Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	275	661
Commercial Doubtful | Commercial and industrial loans
Financing Receivable, Recorded Investment [Line Items]
Loans	275	525
Commercial Doubtful | Residential
Financing Receivable, Recorded Investment [Line Items]
Loans		136
Consumer Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	837,296	764,261
Consumer Performing | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans	15,588
Consumer Performing | Residential
Financing Receivable, Recorded Investment [Line Items]
Loans	470,972	448,494
Consumer Performing | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	277,571	246,101
Consumer Performing | Consumer
Financing Receivable, Recorded Investment [Line Items]
Loans	73,165	69,666
Consumer Non Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	12,179	13,378
Consumer Non Performing | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans	147	945
Consumer Non Performing | Commercial and farmland
Financing Receivable, Recorded Investment [Line Items]
Loans	235	235
Consumer Non Performing | Residential
Financing Receivable, Recorded Investment [Line Items]
Loans	9,674	10,372
Consumer Non Performing | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	1,888	1,709
Consumer Non Performing | Consumer
Financing Receivable, Recorded Investment [Line Items]
Loans	$235	$117

Loans_and_Allowance_Past_Due_A

Loans and Allowance - Past Due Aging of Loan Portfolio by Loan Class (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$3,846,157	$3,549,125
30-59 Days Past Due	22,107	16,864
60-89 Days Past Due	3,149	8,668
Loans 90 Days And Accruing	4,663	1,350
Non-Accrual	48,789	56,402
Total Past Due & Non-Accrual	78,708	83,284
Total Loans	3,924,865	3,632,409
Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	882,596	749,020
30-59 Days Past Due	4,006	2,628
60-89 Days Past Due	53	774
Loans 90 Days And Accruing	2,985
Non-Accrual	7,048	9,283
Total Past Due & Non-Accrual	14,092	12,685
Total Loans	896,688	761,705
Agricultural production financing and other loans to farmers
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	98,236	114,305
30-59 Days Past Due	891	13
60-89 Days Past Due
Loans 90 Days And Accruing
Non-Accrual	5,800	30
Total Past Due & Non-Accrual	6,691	43
Total Loans	104,927	114,348
Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	204,683	171,046
30-59 Days Past Due	1,017	1,058
60-89 Days Past Due	82
Non-Accrual	1,439	4,978
Total Past Due & Non-Accrual	2,538	6,036
Total Loans	207,221	177,082
Commercial and farmland
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,642,016	1,573,403
30-59 Days Past Due	9,846	3,807
60-89 Days Past Due	778	5,801
Loans 90 Days And Accruing	671	703
Non-Accrual	19,350	28,095
Total Past Due & Non-Accrual	30,645	38,406
Total Loans	1,672,661	1,611,809
Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	626,821	595,192
30-59 Days Past Due	4,876	7,156
60-89 Days Past Due	1,831	1,475
Loans 90 Days And Accruing	854	494
Non-Accrual	12,933	12,068
Total Past Due & Non-Accrual	20,494	21,193
Total Loans	647,315	616,385
Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	282,828	251,188
30-59 Days Past Due	1,213	1,652
60-89 Days Past Due	352	563
Loans 90 Days And Accruing	148	153
Non-Accrual	1,988	1,667
Total Past Due & Non-Accrual	3,701	4,035
Total Loans	286,529	255,223
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	72,853	69,061
30-59 Days Past Due	258	550
60-89 Days Past Due	53	55
Loans 90 Days And Accruing	5
Non-Accrual	231	117
Total Past Due & Non-Accrual	547	722
Total Loans	73,400	69,783
Finance Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,106	1,545
Non-Accrual
Total Past Due & Non-Accrual
Total Loans	1,106	1,545
Other loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	35,018	24,365
Non-Accrual		164
Total Past Due & Non-Accrual		164
Total Loans	$35,018	$24,529

Loans_and_Allowance_Summary_of1

Loans and Allowance - Summary of Troubled Debt Restructurings (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
	loan	loan
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	$1,237	$7,753
Post-Modification Recorded Balance	1,257	6,757
Number of Loans	23	32
Commercial and industrial loans
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance		295
Post-Modification Recorded Balance		316
Number of Loans		5
Commercial and farmland
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	259	6,506
Post-Modification Recorded Balance	259	5,492
Number of Loans	1	11
Residential
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	632	809
Post-Modification Recorded Balance	622	804
Number of Loans	9	12
Home equity
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	320
Post-Modification Recorded Balance	350
Number of Loans	11
Consumer
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	26	143
Post-Modification Recorded Balance	$26	$145
Number of Loans	2	4

Loans_and_Allowance_Summary_of2

Loans and Allowance - Summary of Troubled Debt Restructurings by Modification (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Modifications [Line Items]
Modification	$1,263	$4,519
Troubled Debt Restructurings, Term Modifications
Financing Receivable, Modifications [Line Items]
Modification	319	1,823
Troubled Debt Restructurings, Rate Modifications
Financing Receivable, Modifications [Line Items]
Modification	318	275
Troubled Debt Restructurings, Rate and Term Modifications
Financing Receivable, Modifications [Line Items]
Modification	626	2,421
Commercial and industrial loans
Financing Receivable, Modifications [Line Items]
Modification		267
Commercial and industrial loans | Troubled Debt Restructurings, Term Modifications
Financing Receivable, Modifications [Line Items]
Modification		207
Commercial and industrial loans | Troubled Debt Restructurings, Rate and Term Modifications
Financing Receivable, Modifications [Line Items]
Modification		60
Commercial and farmland
Financing Receivable, Modifications [Line Items]
Modification	288	3,373
Commercial and farmland | Troubled Debt Restructurings, Term Modifications
Financing Receivable, Modifications [Line Items]
Modification	288	1,388
Commercial and farmland | Troubled Debt Restructurings, Rate Modifications
Financing Receivable, Modifications [Line Items]
Modification
Commercial and farmland | Troubled Debt Restructurings, Rate and Term Modifications
Financing Receivable, Modifications [Line Items]
Modification		1,985
Residential
Financing Receivable, Modifications [Line Items]
Modification	609	755
Residential | Troubled Debt Restructurings, Term Modifications
Financing Receivable, Modifications [Line Items]
Modification	31	167
Residential | Troubled Debt Restructurings, Rate Modifications
Financing Receivable, Modifications [Line Items]
Modification	218	237
Residential | Troubled Debt Restructurings, Rate and Term Modifications
Financing Receivable, Modifications [Line Items]
Modification	360	351
Home equity
Financing Receivable, Modifications [Line Items]
Modification	343
Home equity | Troubled Debt Restructurings, Rate Modifications
Financing Receivable, Modifications [Line Items]
Modification	100
Home equity | Troubled Debt Restructurings, Rate and Term Modifications
Financing Receivable, Modifications [Line Items]
Modification	243
Consumer
Financing Receivable, Modifications [Line Items]
Modification	23	124
Consumer | Troubled Debt Restructurings, Term Modifications
Financing Receivable, Modifications [Line Items]
Modification		61
Consumer | Troubled Debt Restructurings, Rate Modifications
Financing Receivable, Modifications [Line Items]
Modification		38
Consumer | Troubled Debt Restructurings, Rate and Term Modifications
Financing Receivable, Modifications [Line Items]
Modification	$23	$25

Loans_and_Allowance_Subsequent

Loans and Allowance - Subsequent Default (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
	loan	loan
Financing Receivable, Impaired [Line Items]
Number of Loans	1	5
Recorded Balance	$70	$1,207
Commercial and industrial loans
Financing Receivable, Impaired [Line Items]
Number of Loans		3
Recorded Balance		173
Commercial and farmland
Financing Receivable, Impaired [Line Items]
Number of Loans		2
Recorded Balance		1,034
Residential
Financing Receivable, Impaired [Line Items]
Number of Loans	1
Recorded Balance	$70

Accounting_For_Certain_Loans_A2

Accounting For Certain Loans Acquired In a Purchase - Carrying Amount of Loans Included in Balance Sheet (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$698,457	$690,218
Carrying Amount	658,471	636,182
Allowance	650	229
Carrying Amount	657,821	635,953
Merger with Community Bancshares, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	142,989
Carrying Amount	134,198
Allowance
Carrying Amount	134,198
Merger with CFS Bancorp, Inc. (Citizens)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	509,660	629,184
Carrying Amount	484,949	585,913
Allowance	650
Carrying Amount	484,299	585,913
SCB Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	45,808	61,034
Carrying Amount	39,324	50,269
Allowance		229
Carrying Amount	39,324	50,040
Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	79,124	89,487
Commercial and industrial loans | Merger with Community Bancshares, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	8,168
Commercial and industrial loans | Merger with CFS Bancorp, Inc. (Citizens)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	64,897	81,303
Commercial and industrial loans | SCB Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	6,059	8,184
Agriculture production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	1,993	1,161
Agriculture production financing and other loans to farmers | Merger with Community Bancshares, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	1,100
Agriculture production financing and other loans to farmers | Merger with CFS Bancorp, Inc. (Citizens)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired
Agriculture production financing and other loans to farmers | SCB Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	893	1,161
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	28,176	17,962
Construction | Merger with Community Bancshares, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	19,063
Construction | Merger with CFS Bancorp, Inc. (Citizens)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	9,113	17,962
Construction | SCB Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired
Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	341,195	335,049
Commercial and farmland | Merger with Community Bancshares, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	74,600
Commercial and farmland | Merger with CFS Bancorp, Inc. (Citizens)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	251,002	311,631
Commercial and farmland | SCB Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	15,593	23,418
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	180,643	176,113
Residential | Merger with Community Bancshares, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	28,863
Residential | Merger with CFS Bancorp, Inc. (Citizens)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	144,396	166,754
Residential | SCB Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	7,384	9,359
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	64,883	67,278
Home equity | Merger with Community Bancshares, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	9,881
Home equity | Merger with CFS Bancorp, Inc. (Citizens)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	39,244	49,042
Home equity | SCB Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	15,758	18,236
Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	2,357	2,629
Individuals' loans for household and other personal expenditures | Merger with Community Bancshares, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	1,314
Individuals' loans for household and other personal expenditures | Merger with CFS Bancorp, Inc. (Citizens)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	922	2,360
Individuals' loans for household and other personal expenditures | SCB Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	121	269
Other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	86	539
Other loans | Merger with Community Bancshares, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired
Other loans | Merger with CFS Bancorp, Inc. (Citizens)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	86	132
Other loans | SCB Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired		$407

Accounting_For_Certain_Loans_A3

Accounting For Certain Loans Acquired In a Purchase - Accretable Yield or Income Expected to be Collected (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Beginning balance	$19,299	$5,142
Additions	5,687	13,599
Accretion	-8,883	-2,235
Reclassification from nonaccretable	5,419	2,888
Disposals	-2,086	-95
Ending balance	19,436	19,299
Merger with Community Bancshares, Inc.
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Beginning balance
Additions	5,687
Accretion	-394
Reclassification from nonaccretable	119
Disposals
Ending balance	5,412
Merger with CFS Bancorp, Inc. (Citizens)
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Beginning balance	13,435
Additions		13,599
Accretion	-6,431	-164
Reclassification from nonaccretable	4,501
Disposals	-1,594
Ending balance	9,911	13,435
SCB Bank
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Beginning balance	5,864	5,142	0
Additions
Accretion	-2,058	-2,071	9,774
Reclassification from nonaccretable	799	2,888	-4,632
Disposals	-492	-95	0
Ending balance	$4,113	$5,864	$5,142

Accounting_For_Certain_Loans_A4

Accounting For Certain Loans Acquired In a Purchase - Contractually Required Payments (Details) (USD $)	Feb. 10, 2012	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required payments receivable at acquisition date	$31,143
Nonaccretable difference	9,688
Accretable difference	4,152
Basis in loans at acquisition date	17,303
Merger with Community Bancshares, Inc.
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required payments receivable at acquisition date		26,032
Nonaccretable difference		3,498
Expected cash flows at acquisition date		22,534
Accretable difference		2,234
Basis in loans at acquisition date		20,300
Merger with CFS Bancorp, Inc. (Citizens)
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required payments receivable at acquisition date			109,839
Nonaccretable difference			22,679
Expected cash flows at acquisition date			87,160
Accretable difference			3,502
Basis in loans at acquisition date			$83,658

Premises_and_Equipment_Details

Premises and Equipment - (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Premises and Equipment [Line Items]
Premises and Equipment	$175,430	$164,959
Accumulated Depreciation and Amortization	-97,739	-90,505
Net	77,691	74,454
Land
Premises and Equipment [Line Items]
Premises and Equipment	19,373	17,992
Buildings and Leasehold Improvements
Premises and Equipment [Line Items]
Premises and Equipment	99,451	92,693
Equipment
Premises and Equipment [Line Items]
Premises and Equipment	$56,606	$54,274

Premises_and_Equipment_Narrati

Premises and Equipment - Narrative (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Abstract]
Rent expense	$3,258	$2,608	$2,812

Premises_and_Equipment_Schedul

Premises and Equipment - Schedule of Future Minimum Rental Payments for Operating Leases (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Property, Plant and Equipment [Abstract]
2015	$2,778
2016	2,207
2017	1,514
2018	844
2019	537
After 2019	2,724
Total Future Minimum Obligations	$10,604

Goodwill_Narrative_Details

Goodwill - Narrative (Details) (USD $)	12 Months Ended		0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Nov. 07, 2014	Nov. 12, 2013
Business Acquisition [Line Items]
Goodwill acquired	$13,776,000	$47,573,000
Goodwill impairment loss	0	0
Merger with Community Bancshares, Inc.
Business Acquisition [Line Items]
Goodwill acquired			13,776,000
Merger with CFS Bancorp, Inc. (Citizens)
Business Acquisition [Line Items]
Goodwill acquired				$47,573,000

Goodwill_Details

Goodwill (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Goodwill [Roll Forward]
Goodwill Beginning Balance	$188,948	$141,375
Goodwill acquired	13,776	47,573
Goodwill Ending Balance	$202,724	$188,948

Core_Deposit_and_Other_Intangi2

Core Deposit and Other Intangibles - Narrative (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 07, 2014	Nov. 12, 2013
Business Acquisition [Line Items]
Core deposit amortization	$2,445	$1,649	$1,927
Merger with Community Bancshares, Inc.
Business Acquisition [Line Items]
Core deposit intangible				4,658
Merger with CFS Bancorp, Inc. (Citizens)
Business Acquisition [Line Items]
Core deposit intangible					$7,313

Core_Deposit_and_Other_Intangi3

Core Deposit and Other Intangibles - Schedule of Core Deposit and Other Intangibles (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross carrying amount	$53,702	$46,389
Core deposit intangible and other intangibles acquired	4,658	7,313
Accumulated amortization	-42,329	-39,884
Core Deposit and Other Intangibles	$16,031	$13,818

Core_Deposit_and_Other_Intangi4

Core Deposit and Other Intangibles - Schedule of Estimated Amortization Expense (details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Intangible Assets, Net (Excluding Goodwill) [Abstract]
2015	$2,884
2016	2,817
2017	2,723
2018	1,542
2019	1,293
After 2019	4,772
Core Deposit and Other Intangibles	$16,031	$13,818

Deposits_Schedule_of_Deposits_

Deposits - Schedule of Deposits (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Banking and Thrift [Abstract]
Demand deposits	$2,146,492	$2,018,650
Savings deposits	1,376,707	1,257,994
Certificates and other time deposits of $100,000 or more	260,685	272,660
Other certificates and time deposits	523,010	595,110
Brokered deposits	333,800	87,054
Total Deposits	$4,640,694	$4,231,468

Deposits_Schedule_of_Contractu

Deposits - Schedule of Contractual Maturities of Time Deposits (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Time Deposits, Fiscal Year Maturity [Abstract]
2015	$469,352
2016	256,921
2017	144,348
2018	87,234
2019	52,792
After 2019	106,848
Total	$1,117,495

Borrowings_Schedule_of_Debt_De

Borrowings - Schedule of Debt (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Disclosure [Abstract]
Federal funds purchased	$15,381	$125,645
Securities sold under repurchase agreements	124,539	148,672
Federal Home Loan Bank advances	145,264	122,140
Subordinated debentures and term loans	126,810	126,807
Total Borrowings	$411,994	$523,264

Borrowings_Schedule_of_Maturit

Borrowings - Schedule of Maturities of Long Term Debt (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Securities Sold Under Repurchase Agreements
Debt Instrument [Line Items]
2015	$124,539
2016
Total	124,539
Maximum Amount Outstanding During Period	155,941	161,814
Average Outstanding Amount	130,910	140,126
Federal Home Loan Bank Advances
Debt Instrument [Line Items]
2015	30,780
2016	41,225
2017	15,018
2018	25,637
2019	12,503
After 2019	20,101
Total	145,264
Subordinated Debentures and Term Loans
Debt Instrument [Line Items]
2015	108
2017
After 2019	126,702
Total	$126,810	$126,807

Borrowings_Narrative_Details

Borrowings - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Nov. 01, 2013	Sep. 15, 2012	Jul. 02, 2007
			investor
Debt Instrument [Line Items]
Required value of assets pledged as collateral as a percentage to outstanding advances	146.00%
Interest Rate, Minimum	0.43%
Interest Rate, Maximum	6.81%
Total available remaining borrowing capacity from FHLB	$399,188,000
Private debt issuance, number of institutional investors			4
US Bank, NA
Debt Instrument [Line Items]
Commitment fee percentage	0.25%
Line of credit maximum borrowing capacity	20,000,000
Line of credit	0
5% Senior Notes Due 2028
Debt Instrument [Line Items]
Debt face amount			5,000,000
Interest rate on notes			5.00%
6.75% Subordinated Notes Due 2028
Debt Instrument [Line Items]
Debt face amount			65,000,000
Interest rate on notes			6.75%
Subordinated Debentures and Term Loans
Debt Instrument [Line Items]
Total Debt	126,810,000	126,807,000
Subordinated Debt | First Merchant Capital Trust II
Debt Instrument [Line Items]
Debt face amount			70,000,000		56,702,000
Interest rate on notes	1.80%	1.70%		6.50%
Basis spread on variable rate		1.56%
Revolving Credit Facility | Line of Credit | Bank Of America, N.A.
Debt Instrument [Line Items]
Line of credit maximum borrowing capacity		55,000,000	55,000,000
Term Loan | Line of Credit | Bank Of America, N.A.
Debt Instrument [Line Items]
Line of credit maximum borrowing capacity		5,000,000
Subordinated Debt | Line of Credit | Bank Of America, N.A.
Debt Instrument [Line Items]
Line of credit maximum borrowing capacity		50,000,000
Three Month LIBOR | Subordinated Debt | First Merchant Capital Trust II
Debt Instrument [Line Items]
Basis spread on variable rate	1.56%
One Month LIBOR | US Bank, NA
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%

Derivative_Instruments_and_Hed2

Derivative Instruments and Hedging Activities - Fair Value of Derivative Financial Instruments and Their Classification on Balance Sheet (Detail) (Interest Rate Contract, USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Designated as Hedging Instrument | Other Assets
Derivatives, Fair Value [Line Items]
Asset derivatives	$137	$1,162
Designated as Hedging Instrument | Other Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	2,650	1,021
Not Designated as Hedging Instrument | Other Assets
Derivatives, Fair Value [Line Items]
Asset derivatives	3,730	2,847
Not Designated as Hedging Instrument | Other Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	$3,887	$2,932

Derivative_Instruments_and_Hed3

Derivative Instruments and Hedging Activities - Narrative (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014
Derivative [Line Items]
Termination value of derivatives in a net liability position	$6,785
Derivative collateral posted	7,411
Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount of interest rate derivatives	155,891
Cash Flow Hedging
Derivative [Line Items]
Estimated amount to be transferred from OCI to earnings	1,341
Interest Rate Swap
Derivative [Line Items]
Number of Interest Rate Derivatives Held	5
Notional amount of interest rate derivatives	56,000
Interest Rate Swap | Cash Flow Hedging | Federal Home Loan Bank Advances
Derivative [Line Items]
Notional amount of interest rate derivatives	30,000
Interest rate cap
Derivative [Line Items]
Number of Interest Rate Derivatives Held	1
Notional amount of interest rate derivatives	13,000
Trust Preferred Securities | Interest Rate Swap | Cash Flow Hedging
Derivative [Line Items]
Notional amount of interest rate derivatives	26,000
Trust Preferred Securities | Interest rate cap | Cash Flow Hedging
Derivative [Line Items]
Notional amount of interest rate derivatives	$13,000

Derivative_Instruments_and_Hed4

Derivative Instruments and Hedging Activities - Effect of Derivative Financial Instruments on Income Statement (Detail) (Interest Rate Contract, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Flow Hedging
Derivative [Line Items]
Amount of Loss Recognized in Other Comprehensive Income on Derivative (Effective Portion)	($3,996)	$2,374
Cash Flow Hedging | Interest Expense
Derivative [Line Items]
Amount of Loss Reclassified from Other Comprehensive Income Into Income (Effective Portion)	-1,411	-935	-217
Not Designated as Hedging Instrument | Other Income
Derivative [Line Items]
Amount of Gain (Loss) Recognized Income on Derivative	($73)	$247	($79)

Fair_Values_of_Financial_Instr2

Fair Values of Financial Instruments - Narrative (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2009
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross gains on securities sold	$3,581,000	$487,000	$2,389,000
Investment securities available for sale	549,543,000	536,201,000
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	6,646,000	9,977,000
Significant Unobservable Inputs (Level 3) | Available for Sale Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfer between Levels 1, 2 and 3		350,000
Significant Unobservable Inputs (Level 3) | Held to Maturity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfer between Levels 1, 2 and 3		-16,784,000
Corporate obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross gains on securities sold	1,900,000
Accumulated OTTI on securities	9,400,000
Net impairment losses recognized in earnings				$500,000

Fair_Values_of_Financial_Instr3

Fair Values of Financial Instruments - Fair Value Measurements of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	$549,543	$536,201
Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	542,897	526,224
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	6,646	9,977
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swap liability
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability derivatives	6,537	3,953
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. Treasury
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale		15,973
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. Government-sponsored agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	109	3,545
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	221,982	223,752
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. Government-sponsored mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	319,104	281,252
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	1,702	1,702
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swap asset
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	3,730	3,619
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate cap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	137	390
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	6,611	7,235
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Corporate obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	31	2,738
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	4	4
Fair Value | Fair Value, Measurements, Recurring | Interest rate swap liability
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability derivatives	6,537	3,953
Fair Value | Fair Value, Measurements, Recurring | U.S. Treasury
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale		15,973
Fair Value | Fair Value, Measurements, Recurring | U.S. Government-sponsored agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	109	3,545
Fair Value | Fair Value, Measurements, Recurring | State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	228,593	230,987
Fair Value | Fair Value, Measurements, Recurring | U.S. Government-sponsored mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	319,104	281,252
Fair Value | Fair Value, Measurements, Recurring | Corporate obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	31	2,738
Fair Value | Fair Value, Measurements, Recurring | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	1,706	1,706
Fair Value | Fair Value, Measurements, Recurring | Interest rate swap asset
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	3,730	3,619
Fair Value | Fair Value, Measurements, Recurring | Interest rate cap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	$137	$390

Fair_Values_of_Financial_Instr4

Fair Values of Financial Instruments - Reconciliation of Beginning and Ending Balances of Recurring Fair Value Measurements using Significant Unobservable Level 3 Inputs (Detail) (Fair Value, Measurements, Recurring, Available for Sale Securities, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Measurements, Recurring | Available for Sale Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$9,977	$18,328
Included in other comprehensive income	3,656	1,330
Purchases, issuances, and settlements		7,590
Transfers in/(out) of Level 3		-16,434
Principal (payments)/additions	-6,987	-837
Ending balance	$6,646	$9,977

Fair_Values_of_Financial_Instr5

Fair Values of Financial Instruments - Transfer Between Levels 1, 2 and 3 and Reasons For Those Transfers (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Available-for-sale securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reason for Transfer	Selected state and municipal securities were transferred from Level 2 to Level 3 due to limited availability of similar securities in active markets.
Held to Maturity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reason for Transfer	Selected state and municipal securities were transferred from available for sale to held to maturity. These securities are valued at amortized cost and are no longer classified within the fair value hierarchy.
Significant Other Observable Inputs (Level 2) | Available-for-sale securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfer between Levels 1, 2 and 3	-350
Significant Other Observable Inputs (Level 2) | Held to Maturity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfer between Levels 1, 2 and 3
Significant Unobservable Inputs (Level 3) | Available-for-sale securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfer between Levels 1, 2 and 3	350
Significant Unobservable Inputs (Level 3) | Held to Maturity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfer between Levels 1, 2 and 3	-16,784

Fair_Values_of_Financial_Instr6

Fair Values of Financial Instruments - Valuation Methodologies Used for Instruments Measured at Fair Value on Non-Recurring Basis (Detail) (Fair Value, Measurements, Nonrecurring, USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Significant Unobservable Inputs (Level 3) | Impaired Loans (collateral dependent)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset fair value	$17,134	$12,117
Significant Unobservable Inputs (Level 3) | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset fair value	5,155	6,877
Fair Value | Impaired Loans (collateral dependent)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset fair value	17,134	12,117
Fair Value | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset fair value	$5,155	$6,877

Fair_Values_of_Financial_Instr7

Fair Values of Financial Instruments - Unobservable Inputs Used in Recurring and Nonrecurring Level 3 Fair Value Measurements Other Than Goodwill (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Discounted Cash Flow | State and municipal securities
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	6,611	7,235
Discounted Cash Flow | State and municipal securities | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Maturity/Call date	1 month	1 month
Blend of US Muni BQ curve	A-	A-
Discount rate	0.90%	1.00%
Discounted Cash Flow | State and municipal securities | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Maturity/Call date	15 years	15 years
Blend of US Muni BQ curve	BBB-	BBB-
Discount rate	5.00%	5.00%
Discounted Cash Flow | Corporate obligations and Equity securities
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	35	2,742
Discounted Cash Flow | Corporate obligations and Equity securities | Three Month LIBOR
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Premium for illiquidity	2.00%	2.00%
Collateral Based Measurements | Impaired loans (collateral dependent)
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	17,134	12,117
Collateral Based Measurements | Impaired loans (collateral dependent) | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount to reflect current market conditions and ultimate collectability	0.00%	0.00%
Collateral Based Measurements | Impaired loans (collateral dependent) | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount to reflect current market conditions and ultimate collectability	50.00%	50.00%
Collateral Based Measurements | Impaired loans (collateral dependent) | Weighted Average
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount to reflect current market conditions and ultimate collectability	3.00%	3.00%
Appraisals | Other real estate owned
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	5,155	6,877
Appraisals | Other real estate owned | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount to reflect current market conditions	0.00%	0.00%
Appraisals | Other real estate owned | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount to reflect current market conditions	20.00%	20.00%
Appraisals | Other real estate owned | Weighted Average
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount to reflect current market conditions	7.00%	2.00%

Fair_Values_of_Financial_Instr8

Fair Values of Financial Instruments - Estimated Fair Values of Financial Instruments (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets:
Investment securities available for sale	$549,543	$536,201
Investment securities held to maturity	647,723	560,847
Loans held for sale	7,235	5,331
Carrying Amount
Assets:
Cash and cash equivalents	118,616	109,434
Interest-bearing time deposits	47,520	55,069
Investment securities available for sale	549,543	536,201
Investment securities held to maturity	631,088	559,378
Loans held for sale	7,235	5,331
Loans	3,860,901	3,564,539
FRB and FHLB stock	41,353	38,990
Interest rate swap asset	3,867	4,009
Interest receivable	19,984	18,672
Liabilities:
Deposits	4,640,694	4,231,468
Borrowings:
Federal funds purchased	15,381	125,645
Securities sold under repurchase agreements	124,539	148,672
FHLB Advances	145,264	122,140
Subordinated debentures and term loans	126,810	126,807
Interest rate swap liability	6,537	3,953
Interest payable	3,201	1,771
Fair Value, Inputs, Level 1 [Member]
Assets:
Cash and cash equivalents	118,616	109,434
Interest-bearing time deposits	47,520	55,069
Liabilities:
Deposits	3,523,199	3,082,117
Significant Other Observable Inputs (Level 2)
Assets:
Investment securities available for sale	542,897	526,224
Investment securities held to maturity	614,457	525,998
Loans held for sale	7,235	5,331
FRB and FHLB stock	41,353	38,990
Interest rate swap asset	3,867	4,009
Interest receivable	19,984	18,672
Liabilities:
Deposits	1,099,610	934,937
Borrowings:
Federal funds purchased	15,381	125,645
Securities sold under repurchase agreements	124,539	148,852
FHLB Advances	146,669	122,962
Subordinated debentures and term loans	92,802	82,607
Interest rate swap liability	6,537	3,953
Interest payable	3,201	1,771
Significant Unobservable Inputs (Level 3)
Assets:
Investment securities available for sale	6,646	9,977
Investment securities held to maturity	33,266	34,849
Loans	$3,810,912	$3,506,615

Commitments_and_Contingent_Lia2

Commitments and Contingent Liabilities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Loan commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Amounts of commitments	$1,617,552	$1,216,470
Standby letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Amounts of commitments	$52,655	$41,508

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 12, 2013	Nov. 07, 2014	Nov. 22, 2013	Jul. 02, 2013	Jan. 03, 2013	Sep. 22, 2011	Dec. 31, 2011
Class of Stock [Line Items]
Stockholders' equity	$726,827,000	$634,923,000	$552,236,000							$514,467,000
Dividend reinvestment and stock purchase plan, stockholder's maximum amount of cash payments per quarter in purchase of common stock	2,500
Preferred stock, liquidation value (in dollars per share)	$1,000	$1,000
Price of preferred stock redeemed	1,067,000	491,000	235,000
Preferred stock, shares outstanding	125	125
Value of stock issued as a part of acquisition	34,981,000	135,642,000
Merger with CFS Bancorp, Inc. (Citizens)
Class of Stock [Line Items]
Percentage of interest acquired				100.00%
Stock issued as a part of acquisition (in shares)				7,100,000
Value of stock issued as a part of acquisition				135,600,000
Total purchase price				135,642,000
Merger with Community Bancshares, Inc.
Class of Stock [Line Items]
Percentage of interest acquired					100.00%
Stock issued as a part of acquisition (in shares)					1,600,000
Value of stock issued as a part of acquisition					35,000,000
Number of shares of common stock					4.0926
Share price					$85.94
Cash paid in acquisition					14,200,000
Total purchase price					49,189,000
Series B Preferred Stock
Class of Stock [Line Items]
Number of new stock issued during the period (shares)									90,782.94
Preferred stock, liquidation value (in dollars per share)									$1,000
Number of new stock issued during the period value									90,782,940
Preferred stock redeemed (in shares)						34,043	34,044	22,695.94
Price of preferred stock redeemed						34,043,000	34,044,000	22,695,940
Preferred stock, shares outstanding	0						34,043	68,087
Series B Preferred Stock remaining liquidation amount							34,000,000	68,000,000
Subsidiaries
Class of Stock [Line Items]
Amount available for dividends	23,340,000
Stockholders' equity	818,420,000
Stockholders' equity restricted from dividend distribution	$795,080,000
CFS Bancorp | Merger with CFS Bancorp, Inc. (Citizens)
Class of Stock [Line Items]
Percentage of common stock received per shares owned through acquisition				0.65%

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income (Loss) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income [Roll Forward]
AOCI - beginning balance	($6,410)	($5,499)
Other comprehensive income before reclassifications	6,528	-2,349
Amounts reclassified from accumulated other comprehensive income	-1,748	1,438
Period change	4,780	-911	-1,897
AOCI - ending balance	-1,630	-6,410	-5,499
Unrealized Gains (Losses) on Securities Available for Sale
Accumulated Other Comprehensive Income [Roll Forward]
AOCI - beginning balance	1,566	17,904
Other comprehensive income before reclassifications	14,860	-16,021
Amounts reclassified from accumulated other comprehensive income	-2,328	-317
Period change	12,532	-16,338
AOCI - ending balance	14,098	1,566
Unrealized Gains (Losses) on Securities Available for Sale for which a Portion of Other-Than-Temporary Impairment has been Recognized in Income
Accumulated Other Comprehensive Income [Roll Forward]
AOCI - beginning balance	-1,847	-3,272
Other comprehensive income before reclassifications	1,847	1,425
Amounts reclassified from accumulated other comprehensive income
Period change	1,847	1,425
AOCI - ending balance	0	-1,847
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income [Roll Forward]
AOCI - beginning balance	-501	-2,652
Other comprehensive income before reclassifications	-2,599	1,543
Amounts reclassified from accumulated other comprehensive income	918	608
Period change	-1,681	2,151
AOCI - ending balance	-2,182	-501
Unrealized Gains (Losses) on Defined Benefit Plans
Accumulated Other Comprehensive Income [Roll Forward]
AOCI - beginning balance	-5,628	-17,479
Other comprehensive income before reclassifications	-7,580	10,704
Amounts reclassified from accumulated other comprehensive income	-338	1,147
Period change	-7,918	11,851
AOCI - ending balance	($13,546)	($5,628)

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income (Loss) - Reclassifications (Loss) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Interest expense - subordinated debentures and term loans									($6,616)	($3,531)	($5,213)
Other expenses - salaries and employee benefits									-96,499	-85,413	-79,398
Income tax expense	-5,517	-5,862	-5,642	-4,369	-3,187	-2,667	-4,155	-4,668	-21,390	-14,677	-15,867
NET INCOME	15,260	16,122	15,160	13,620	11,447	10,403	10,815	11,865	60,162	44,530	45,122
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
NET INCOME									1,748	-1,438	1,478
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period | Unrealized gains (losses) on available for sale securities
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Other income - net realized gains on sales of available for sale securities									3,581	487	2,389
Income tax expense									-1,253	-170	-835
NET INCOME									2,328	317	1,554
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period | Unrealized gains (losses) on cash flow hedges
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Interest expense - subordinated debentures and term loans									-1,411	-935	-217
Income tax expense									493	327	76
NET INCOME									-918	-608	-141
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period | Unrealized gains (losses) on defined benefit plans
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Other expenses - salaries and employee benefits									520	-1,765	100
Income tax expense									-182	618	-35
NET INCOME									$338	($1,147)	$65

Regulatory_Capital_Details

Regulatory Capital (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Capital [Abstract]
Total Capital (to Risk-weighted Assets), Actual Amount	$685,507	$599,966
Total Capital (to Risk-weighted Assets) Required for Adequate Capital, Amount	357,581	330,107
Tier One Risk Based Capital [Abstract]
Tier I Capital (to Risk-weighted Assets), Actual Amount	564,535	483,186
Tier I Capital (to Risk-weighted Assets) Required for Adequate Capital, Amount	178,791	165,053
Tier One Leverage Capital [Abstract]
Tier I Capital (to Average Assets), Actual	564,535	483,186
Tier I Capital (to Average Assets) Required for Adequate Capital, Amount	222,533	189,485
Risk Based Ratios [Abstract]
Total Capital (to Risk-weighted Assets) Actual Ratio	15.34%	14.54%
Total Capital (to Risk-weighted Assets) Required for Adequate Capital, Ratio	8.00%	8.00%
Tier I Capital (to Risk-weighted Assets), Ratio	12.63%	11.71%
Tier I Capital (to Risk-weighted Assets) Required for Adequate Capital, Ratio	4.00%	4.00%
Leverage Ratios [Abstract]
Tier I Capital (to Average Assets), Ratio	10.15%	10.20%
Tier I Capital (to Average Assets) Required for Adequate Capital, Ratio	4.00%	4.00%
First Merchants Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-weighted Assets) Well Capitalized Ratio	10.00%
Tier I Capital (to Risk-weighted Assets) Well Capitalized Ratio	6.00%
Tier I Capital (to Average Assets) Well Capitalized Ratio	5.00%
Capital [Abstract]
Total Capital (to Risk-weighted Assets), Actual Amount	653,169	599,272
Total Capital (to Risk-weighted Assets) Required for Adequate Capital, Amount	356,884	329,344
Tier One Risk Based Capital [Abstract]
Tier I Capital (to Risk-weighted Assets), Actual Amount	597,305	547,655
Tier I Capital (to Risk-weighted Assets) Required for Adequate Capital, Amount	178,442	164,672
Tier One Leverage Capital [Abstract]
Tier I Capital (to Average Assets), Actual	597,305	547,655
Tier I Capital (to Average Assets) Required for Adequate Capital, Amount	$226,339	$189,095
Risk Based Ratios [Abstract]
Total Capital (to Risk-weighted Assets) Actual Ratio	14.64%	14.56%
Total Capital (to Risk-weighted Assets) Required for Adequate Capital, Ratio	8.00%	8.00%
Tier I Capital (to Risk-weighted Assets), Ratio	13.39%	13.30%
Tier I Capital (to Risk-weighted Assets) Required for Adequate Capital, Ratio	4.00%	4.00%
Leverage Ratios [Abstract]
Tier I Capital (to Average Assets), Ratio	10.56%	11.58%
Tier I Capital (to Average Assets) Required for Adequate Capital, Ratio	4.00%	4.00%

Loan_Servicing_Details

Loan Servicing (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Banking and Thrift [Abstract]
Unpaid balance of loans serviced for others	$254,223	$271,871	$167,879

ShareBased_Compensation_Narrat

Share-Based Compensation - Narrative (Detail) (USD $)	12 Months Ended			3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of average closing price to be paid by employees	85.00%
Share-based compensation	$2,177,000	$1,773,000	$1,492,000
Estimated pre-vesting forfeiture rate	5.50%
Weighted-average grant date fair value for stock options (in dollars per share)	$8.13	$5.73	$3.97
Aggregate intrinsic value of stock options exercised	392,000	143,000
Stock options exercised	504,000	115,000	78,000
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock purchases through advance payroll deductions in a calendar year	25,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option term	10 years
Stock options vesting percentage	100.00%
Estimated pre-vesting forfeiture rate	5.46%	4.73%	4.77%
Unrecognized compensation expense	4,000			4,000
Unrecognized compensation expense expected recognition period	0 years 1 month 20 days
Stock Options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested period	6 months
Stock Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested period	2 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested period	3 years
Unrecognized compensation expense	2,618,000			2,618,000
Unrecognized compensation expense expected recognition period	1 year 1 month 28 days
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	0			0
Grant date fair value of ESPP options				$20,000

ShareBased_Compensation_Assump

Share-Based Compensation - Assumptions Used (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Forfeiture rate	5.50%
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.41%	1.25%	1.36%
Expected price volatility	45.05%	45.68%	46.22%
Dividend yield	2.73%	2.96%	3.29%
Forfeiture rate	5.46%	4.73%	4.77%
Weighted-average expected life, until exercise	7 years 8 months 28 days	7 years 3 months 9 days	7 years 2 months 12 days

ShareBased_Compensation_Compon

Share-Based Compensation - Components of Awards (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax compensation expense	$2,177	$1,773	$1,492
Income tax benefit	-726	-547	-451
Total share-based compensation expense, net of income taxes	1,451	1,226	1,041
Stock and ESPP Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax compensation expense	237	253	284
Income tax benefit	-47	-16	-23
Total share-based compensation expense, net of income taxes	190	237	261
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax compensation expense	1,940	1,520	1,208
Income tax benefit	-679	-531	-428
Total share-based compensation expense, net of income taxes	$1,261	$989	$780

ShareBased_Compensation_Stock_

Share-Based Compensation - Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2012
Number of Shares
Beginning balance	958,786
Granted	13,500
Exercised	-41,249
Canceled	-193,106
Ending balance	737,931
Vested and Expected to Vest, Number of Shares	737,931
Exercisable, Number of Shares	715,431
Weighted-Average Exercise Price
Beginning balance	$21.32	$21.58
Granted	$21.65
Exercised	$12.21
Canceled	$24.42
Ending balance	$20.99	$21.58
Vested and Expected to Vest, Weighted-Average Exercise Price	$20.99
Exercisable, Weighted-Average Exercise Price	$21.05
Weighted Average Remaining Contractual Term (in Years)
Outstanding (in years)	3 years 1 month 0 days
Vested and Expected to Vest (in years)	3 years 1 month 0 days
Exercisable (in years)	2 years 10 months 25 days
Aggregate Intrinsic Value
Outstanding	$2,645,356
Vested and Expected to Vest	2,645,356
Exercisable	$2,563,636

ShareBased_Compensation_Unvest

Share-Based Compensation - Unvested RSAs Outstanding (Detail) (Restricted Stock, USD $)	12 Months Ended
	Dec. 31, 2014
Restricted Stock
Number of Shares
Unvested RSAs, Beginning Balance	429,002
Granted	98,611
Forfeited	-9,717
Vested	-132,446
Unvested RSAs, Ending Balance	385,450
Weighted-Average Grant Date Fair Value
Unvested RSAs, Beginning Balance	$12.51
Granted	$20.54
Forfeited	$15.78
Vested	$9.16
Unvested RSAs, Ending Balance	$15.65

Pension_and_Other_Post_Retirem2

Pension and Other Post Retirement Benefit Plans - Narrative (Details) (USD $)	0 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 01, 2005	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Percentage of employees covered by plan		25.00%
Minimum participant attained age	55 years
Requisite service period	10 years
Discount rate		4.00%	4.80%	4.00%
Percentage of the premiums paid by plan participants		100.00%
Accumulated benefit obligation		$80,650	$62,263
Amount of discretionary contributions made by employer to defined contribution plan, percent		50.00%
Maximum annual contribution percentage per employee		6.00%
Requisite service period		1000 hours
Employer percentage contribution		2.00%
Vesting period		5 years
Expense recognized in the period		3,396	3,138	2,914
Obligations payable		1,811	1,534
Post retirement plan expense		97	519	477
Fair value of plan assets		77,139	69,871	62,865
Minimum
Defined Benefit Plan Disclosure [Line Items]
Age of plan participants		55 years
Maximum
Defined Benefit Plan Disclosure [Line Items]
Age of plan participants		65 years
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		57,413	51,176
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$19,726	$18,695
Debt securities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Maturities of debt securities		15 days	2 days
Debt securities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Maturities of debt securities		9 years 7 months 3 days	9 years 7 months 10 days
Debt securities | Weighted Average
Defined Benefit Plan Disclosure [Line Items]
Maturities of debt securities		5 years 0 months 7 days	4 years 7 months 18 days

Pension_and_Other_Post_Retirem3

Pension and Other Post Retirement Benefit Plans - Schedule of Changes in Benefit Obligation, and Plan Assets, Funded Status of the Plan, Assets and Liabilities Recognized in the Balance Sheets (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Change in Benefit Obligation:
Benefit obligation at beginning of year	$62,270	$69,166
Service cost	73	131	161
Interest cost	3,235	2,670	2,990
Actuarial loss (gain)	12,968	-5,597
Benefits paid	-5,541	-4,100
Net transfers in from CFS acquisition	7,645
Benefit obligation at end of year	80,650	62,270	69,166
Change in Plan Assets:
Fair value of plan assets at beginning of year	69,871	62,865
Actual return on plan assets	5,232	10,610
Employer contributions	504	496
Benefits paid	-5,541	-4,100
CFS acquisition	7,073
End of year	77,139	69,871	62,865
Funded status at end of year	-3,511	7,601
Assets and Liabilities Recognized in the Balance Sheets:
Deferred tax asset	8,541	4,266
Assets	1,329	12,383
Liabilities	4,840	4,782
Amounts Recognized in Accumulated Other Comprehensive Income Not Yet Recognized as Components of Net Periodic (Benefit) Cost Consist of:
Accumulated loss	-15,863	-7,922
Prior service credit	-346	-28
Total	($16,209)	($7,950)

Pension_and_Other_Post_Retirem4

Pension and Other Post Retirement Benefit Plans - Schedule of Accumulated Benefit Obligation in Excess of Plan Assets (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Compensation and Retirement Disclosure [Abstract]
Projected benefit obligation	$4,840	$4,782
Accumulated benefit obligation	4,840	4,782
Fair value of plan assets

Pension_and_Other_Post_Retirem5

Pension and Other Post Retirement Benefit Plans - Schedule of Net Periodic Benefit Costs (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Compensation and Retirement Disclosure [Abstract]
Service cost	$73	$131	$161
Interest cost	3,235	2,670	2,990
Expected return on plan assets	-4,467	-4,265	-4,216
Amortization of prior service costs	81	25	25
Amortization of net loss	478	2,131	2,207
Net periodic pension (benefit) cost	($600)	$692	$1,167

Pension_and_Other_Post_Retirem6

Pension and Other Post Retirement Benefit Plans - Other Comprehensive Income (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension (benefit) cost	$600	($692)	($1,167)
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension (benefit) cost	-600	692	1,167
Net gain (loss)	-12,203	11,942	-1,242
Amortization of loss	478	2,131	2,207
Amortization of prior service cost	81	25	25
Total recognized in other comprehensive income (loss)	-11,644	14,098	990
Total recognized in net periodic pension cost and other comprehensive income (loss)	($11,044)	$13,406	($177)

Pension_and_Other_Post_Retirem7

Pension and Other Post Retirement Benefit Plans - Amount To Be Amortized From Accumulated Other Comprehensive Income, Next Fiscal Year (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract]
Amortization of net loss	($1,770)	($533)	($2,158)
Amortization of prior service cost	-64	-25	-25
Total	($1,834)	($558)	($2,183)

Pension_and_Other_Post_Retirem8

Pension and Other Post Retirement Benefit Plans - Schedule of Weighted Average Assumptions Used to Determine Benefit Obligation and Benefit Cost (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Weighted-average Assumptions Used to Determine Benefit Obligation:
Discount rate	4.00%	4.80%	4.00%
Rate of compensation increase for accruing active participants	3.00%	3.00%	3.00%
Weighted-average Assumptions Used to Determine Cost:
Discount rate	4.80%	4.00%	4.50%
Expected return on plan assets	6.00%	7.00%	7.00%
Rate of compensation increase for accruing active participants	3.00%	3.00%	4.00%

Pension_and_Other_Post_Retirem9

Pension and Other Post Retirement Benefit Plans - Schedule of Expected Future Benefit Payments (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Compensation and Retirement Disclosure [Abstract]
2015	$4,761
2016	4,757
2017	4,751
2018	4,783
2019	4,997
After 2019	25,125
Total	$49,174

Recovered_Sheet1

Pension and Other Post Retirement Benefit Plans - Schedule of Plan Assets by Category (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Actual Plan Asset Allocations	100.00%	100.00%
Target Plan Asset Allocations	100.00%	100.00%
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Actual Plan Asset Allocations	2.60%	2.70%
Target Plan Asset Allocations	2.00%	2.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Actual Plan Asset Allocations	58.70%	62.20%
Target Plan Asset Allocations	60.00%	60.00%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Actual Plan Asset Allocations	36.50%	33.20%
Target Plan Asset Allocations	36.00%	36.00%
Alternative investments
Defined Benefit Plan Disclosure [Line Items]
Actual Plan Asset Allocations	2.20%	1.90%
Target Plan Asset Allocations	2.00%	2.00%

Recovered_Sheet2

Pension and Other Post Retirement Benefit Plans - Schedule of Plan Assets by Level (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$77,139	$69,871	$62,865
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	57,413	51,176
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,032	1,864
Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate Bonds and Notes
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	9,384	6,076
Quoted Prices in Active Markets for Identical Assets (Level 1) | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,376	1,375
Quoted Prices in Active Markets for Identical Assets (Level 1) | Taxable Bond
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,987	3,901
Quoted Prices in Active Markets for Identical Assets (Level 1) | Large Cap Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	21,185	20,617
Quoted Prices in Active Markets for Identical Assets (Level 1) | Mid Cap Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	9,434	8,721
Quoted Prices in Active Markets for Identical Assets (Level 1) | Small Cap Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,872	3,584
Quoted Prices in Active Markets for Identical Assets (Level 1) | International Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,474	3,727
Quoted Prices in Active Markets for Identical Assets (Level 1) | Specialty Alternative Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,669	1,311
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	19,726	18,695
Significant Other Observable Inputs (Level 2) | Government Agency and Municipal Bonds and Notes
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	8,252	8,263
Significant Other Observable Inputs (Level 2) | Certificates of Deposit
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,001	607
Significant Other Observable Inputs (Level 2) | Common Bond Fund
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,615	5,318
Significant Other Observable Inputs (Level 2) | Common Equity Fund
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	5,858	4,507
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	77,139	69,871
Fair Value | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,032	1,864
Fair Value | Corporate Bonds and Notes
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	9,384	6,076
Fair Value | Government Agency and Municipal Bonds and Notes
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	8,252	8,263
Fair Value | Certificates of Deposit
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,001	607
Fair Value | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,376	1,375
Fair Value | Common Bond Fund
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,615	5,318
Fair Value | Common Equity Fund
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	5,858	4,507
Fair Value | Taxable Bond
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,987	3,901
Fair Value | Large Cap Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	21,185	20,617
Fair Value | Mid Cap Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	9,434	8,721
Fair Value | Small Cap Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,872	3,584
Fair Value | International Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,474	3,727
Fair Value | Specialty Alternative Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$1,669	$1,311

Income_Tax_Details

Income Tax (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Currently Payable:
Federal									($1,661)	$738	($23)
Deferred:
Federal									22,541	13,939	15,890
State									510
Total Income Tax Expense	5,517	5,862	5,642	4,369	3,187	2,667	4,155	4,668	21,390	14,677	15,867
Reconciliation of Federal Statutory to Actual Tax Expense:
Federal Statutory Income Tax at 35%									28,543	20,722	21,347
Tax-exempt Interest Income									-5,148	-3,923	-3,716
Stock Compensation									36	50	76
Earnings on Life Insurance									-1,271	-905	-1,187
Tax Credits									-911	-857	-73
Other									141	-410	-580
Total Income Tax Expense	$5,517	$5,862	$5,642	$4,369	$3,187	$2,667	$4,155	$4,668	$21,390	$14,677	$15,867
Federal statutory income tax rate									35.00%	35.00%	35.00%

Income_Tax_Deferred_Tax_Assets

Income Tax - Deferred Tax Assets and Liabilities (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Assets:
Differences in Accounting for Loan Losses	$26,665	$28,064
Differences in Accounting for Loan Fees	747	736
Differences in Accounting for Loans and Securities	9,910	13,579
Deferred Compensation	5,234	5,479
Difference in Accounting for Pensions and Other Employee Benefits	1,084
Federal & State Income Tax Loss Carryforward and Credits	23,977	24,981
Net Unrealized Loss on Securities Available for Sale		151
Other	8,535	12,828
Total Assets	76,152	85,818
Liabilities:
Differences in Depreciation Methods	8,220	8,008
Difference in Accounting for Pensions and Other Employee Benefits		1,096
State Income Tax	591	354
Net Unrealized Gain on Securities Available for Sale	7,591
Gain on FDIC Modified Whole Bank Transaction	1,694	2,147
Other	1,096	1,257
Total Liabilities	19,192	12,862
Net Deferred Tax Asset Before Valuation Allowance	56,960	72,956
Valuation allowance:
Beginning Balance	-17,171	-13,859
Decrease/(Increase) During the Year	-397	-3,312
Ending Balance	-17,568	-17,171
Net Deferred Tax Asset	$39,392	$55,785

Income_Tax_Narrative_Details

Income Tax - Narrative (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Valuation Allowance [Line Items]
Tax expense applicable to security gains and losses, including unrealized losses relating to other-than-temporary charges	$760	$157	$759
Increase (decrease) in deferred tax assets	16,393
Valuation allowance	17,568	17,171	13,859
Additional paid-in capital	431,220	393,783
Unrecorded deferred tax liability	4,688
Merger with CFS Bancorp, Inc. (Citizens)
Valuation Allowance [Line Items]
Additional paid-in capital	13,393
State and Local Jurisdiction
Valuation Allowance [Line Items]
Valuation allowance	17,568
State tax loss carryforward	143,467
Valuation allowance on state loss carryforward	142,358
Available-for-sale securities
Valuation Allowance [Line Items]
Increase in deferred tax liability	7,742
Deferred Compensation
Valuation Allowance [Line Items]
Increase (decrease) in deferred tax assets	-2,180
Loans
Valuation Allowance [Line Items]
Increase (decrease) in deferred tax assets	3,669
Other than temporary impairment on securities
Valuation Allowance [Line Items]
Increase (decrease) in deferred tax assets	3,261
Other real estate owned
Valuation Allowance [Line Items]
Increase (decrease) in deferred tax assets	$1,988

Net_Income_Per_Share_Details

Net Income Per Share (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Net income	$15,260	$16,122	$15,160	$13,620	$11,447	$10,403	$10,815	$11,865	$60,162	$44,530	$45,122
Preferred stock dividends					-241	-430	-852	-857		-2,380	-4,539
Net income available to common stockholders	15,260	16,122	15,160	13,620	11,206	9,973	9,963	11,008	60,162	42,150	40,583
Net income available to common stockholders									$60,162	$42,150	$40,583
Weighted-Average Shares
Net income available to common stockholders	37,018,014	36,054,867	36,026,763	35,956,436	32,597,145	28,806,809	28,783,407	28,716,987	36,266,356	29,731,420	28,632,915
Effect of dilutive stock options and warrants									288,253	276,960	213,769
Net income available to common stockholders	37,323,276	36,328,981	36,294,149	36,260,624	32,912,605	29,081,472	29,023,513	28,971,238	36,554,609	30,008,380	28,846,684
Basic net income per share:
Net income available to common stockholders	$0.41	$0.45	$0.42	$0.38	$0.34	$0.35	$0.35	$0.38	$1.66	$1.42	$1.42
Diluted net income per share:
Net income available to common stockholders	$0.41	$0.45	$0.41	$0.38	$0.34	$0.35	$0.34	$0.38	$1.65	$1.41	$1.41

Net_Income_Per_Share_Narrative

Net Income Per Share - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Stock options not included in the earnings per share calculation (shares)	543,514	800,674	820,706
Weighted average exercise price (per share)	$20.99	$21.32	$21.58

Quarterly_Results_of_Operation2

Quarterly Results of Operations (Unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Interest income	$53,053	$53,290	$51,527	$51,009	$45,707	$40,736	$40,653	$43,738	$208,879	$170,834	$175,949
Interest expense	5,893	5,424	5,408	5,117	4,572	3,714	4,003	4,280	21,842	16,569	23,613
Net interest income	47,160	47,866	46,119	45,892	41,135	37,022	36,650	39,458	187,037	154,265	152,336
Provision for loan losses	960	1,600			1,016	1,533	1,997	2,102	2,560	6,648	18,534
Net interest income after provision for loan losses	46,200	46,266	46,119	45,892	40,119	35,489	34,653	37,356	184,477	147,617	133,802
Non-interest income	16,254	18,294	15,933	15,186	15,073	11,800	14,059	13,877	65,667	54,809	64,302
Non-interest expense	41,677	42,576	41,250	43,089	40,558	34,219	33,742	34,700	168,592	143,219	137,115
Income before income tax expense	20,777	21,984	20,802	17,989	14,634	13,070	14,970	16,533	81,552	59,207	60,989
Income tax expense	5,517	5,862	5,642	4,369	3,187	2,667	4,155	4,668	21,390	14,677	15,867
Net income	15,260	16,122	15,160	13,620	11,447	10,403	10,815	11,865	60,162	44,530	45,122
Preferred stock dividends					-241	-430	-852	-857		-2,380	-4,539
Net income available to common stockholders	$15,260	$16,122	$15,160	$13,620	$11,206	$9,973	$9,963	$11,008	$60,162	$42,150	$40,583
Basic EPS	$0.41	$0.45	$0.42	$0.38	$0.34	$0.35	$0.35	$0.38	$1.66	$1.42	$1.42
Diluted EPS	$0.41	$0.45	$0.41	$0.38	$0.34	$0.35	$0.34	$0.38	$1.65	$1.41	$1.41
Average Shares Outstanding:
Basic	37,018,014	36,054,867	36,026,763	35,956,436	32,597,145	28,806,809	28,783,407	28,716,987	36,266,356	29,731,420	28,632,915
Diluted	37,323,276	36,328,981	36,294,149	36,260,624	32,912,605	29,081,472	29,023,513	28,971,238	36,554,609	30,008,380	28,846,684

Condensed_Financial_Informatio2

Condensed Financial Information (parent company only) - Balance Sheet (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
ASSETS
Goodwill	$202,724	$188,948	$141,375
Other assets	20,764	28,997
TOTAL ASSETS	5,824,127	5,437,262
LIABILITIES
Borrowings	411,994	523,264
Other liabilities	41,411	45,836
Total liabilities	5,097,300	4,802,339
Stockholders' equity	726,827	634,923	552,236	514,467
Total liabilities and stockholders' equity	5,824,127	5,437,262
Parent
ASSETS
Cash	36,044	13,228
Investment in subsidiaries	820,123	745,818
Goodwill	448	448
Other assets	6,281	8,695
TOTAL ASSETS	862,896	768,189
LIABILITIES
Borrowings	126,702	126,702
Other liabilities	9,367	6,564
Total liabilities	136,069	133,266
Stockholders' equity	726,827	634,923
Total liabilities and stockholders' equity	$862,896	$768,189

Condensed_Financial_Informatio3

Condensed Financial Information (parent company only) - Statement of Operations (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income
Other income									$5,705	$4,197	$1,808
Expenses
Interest expense	5,893	5,424	5,408	5,117	4,572	3,714	4,003	4,280	21,842	16,569	23,613
Salaries and employee benefits									96,499	85,413	79,398
Other expenses									14,239	11,142	11,505
INCOME BEFORE INCOME TAX	20,777	21,984	20,802	17,989	14,634	13,070	14,970	16,533	81,552	59,207	60,989
Income tax benefit	-5,517	-5,862	-5,642	-4,369	-3,187	-2,667	-4,155	-4,668	-21,390	-14,677	-15,867
Preferred stock dividends					-241	-430	-852	-857		-2,380	-4,539
Net income available to common stockholders	15,260	16,122	15,160	13,620	11,206	9,973	9,963	11,008	60,162	42,150	40,583
Net income	15,260	16,122	15,160	13,620	11,447	10,403	10,815	11,865	60,162	44,530	45,122
Other comprehensive income (loss)									4,780	-911	-1,897
Comprehensive income									64,942	43,619	43,225
Parent
Income
Dividends from subsidiaries									53,231	63,732	30,096
Other income									538	45	85
Total income									53,769	63,777	30,181
Expenses
Interest expense									6,616	3,531	4,655
Salaries and employee benefits									3,128	3,284	3,194
Net occupancy and equipment expenses									442	258	312
Telephone expenses									27	42	30
Postage and courier expenses											1
Other expenses									1,972	2,617	1,502
Total expenses									12,185	9,732	9,694
INCOME BEFORE INCOME TAX									41,584	54,045	20,487
Income tax benefit									3,999	3,153	3,316
Income before equity in undistributed income of subsidiaries									45,583	57,198	23,803
Equity in undistributed (distributions in excess of) income of subsidiaries									14,579	-12,668	21,319
Net income									60,162	44,530	45,122
Preferred stock dividends										-2,380	-4,539
Net income available to common stockholders									60,162	42,150	40,583
Net income									60,162	44,530	45,122
Other comprehensive income (loss)									4,780	-911	-1,897
Comprehensive income									$64,942	$43,619	$43,225

Condensed_Financial_Informatio4

Condensed Financial Information (parent company only) - Statement of Cash Flows (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Net income	$60,162	$44,530	$45,122
Adjustments to Reconcile Net Income to Net Cash:
Share-based compensation	2,177	1,773	1,492
Net Change in:
Net cash provided by operating activities	75,840	183,131	70,269
Cash Flows from Investing Activities:
Cash received (paid) in acquisition	-14,208		17,200
Other	5,889	-2,768	-2,065
Net cash provided by (used in) investing activities	-125,991	-138,162	11,886
Cash Flows from Financing Activities:
Repayment of borrowings	-789,563	-163,838	-271,005
Preferred stock redemption under small business lending fund		-90,783
Stock issued under employee benefit plans	478	479	449
Stock issued under dividend reinvestment and stock purchase plan	523	325	202
Stock options exercised	504	115	78
Stock redeemed	-1,067	-491	-235
Net cash provided by (used in) financing activities	59,333	-36,995	-54,007
Net change in cash	9,182	7,974	28,148
Cash and Cash Equivalents, January 1	109,434	101,460	73,312
Cash and Cash Equivalents, December 31	118,616	109,434	101,460
Parent
Condensed Financial Statements, Captions [Line Items]
Net income	60,162	44,530	45,122
Adjustments to Reconcile Net Income to Net Cash:
Share-based compensation	887	778	632
Distributions in excess of (equity in undistributed) income of subsidiaries	-14,579	12,668	-21,319
Net Change in:
Other assets	2,425	-1,354	1,902
Other liabilities	1,466	-8,438	1,122
Investment in subsidiaries - operating activities	-4,517	12,991	-1,755
Net cash provided by operating activities	45,844	61,175	25,704
Cash Flows from Investing Activities:
Cash Flow From Investing Activities:			-126
Cash received (paid) in acquisition	-12,832
Other		240
Net cash provided by (used in) investing activities	-12,832	240	-126
Cash Flows from Financing Activities:
Cash dividends	-10,694	-7,992	-7,442
Repayment of borrowings		-55,000	-4,124
Proceeds from issuance of long-term debt		70,000
Preferred stock redemption under small business lending fund		-90,783
Stock issued under employee benefit plans	478	479	449
Stock issued under dividend reinvestment and stock purchase plan	523	325	202
Stock options exercised	564	115	78
Stock redeemed	-1,067	-491	-235
Net cash provided by (used in) financing activities	-10,196	-83,347	-11,072
Net change in cash	22,816	-21,932	14,506
Cash and Cash Equivalents, January 1	13,228	35,160	20,654
Cash and Cash Equivalents, December 31	$36,044	$13,228	$35,160

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Common stock, par value per share		$0.13	$0.13
C Financial Corporation
Business Acquisition [Line Items]
Common stock, par value per share		$1
Merger with C Financial Corporation | Scenario, Forecast
Business Acquisition [Line Items]
Cash paid in acquisition	$14,500