First Merchants (FRME) 10-K 27 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Feb. 20, 2019	Jun. 30, 2018
Document Documentand Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Trading Symbol	FRME
Entity Registrant Name	FIRST MERCHANTS CORP
Entity Central Index Key	712,534
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		49,697,568
Entity Public Float			$ 2,286,601

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
ASSETS
Cash and cash equivalents	$ 139,247	$ 154,905
Interest-bearing time deposits	36,963	35,027
Investment securities available for sale	1,142,195	999,947
Investment securities held to maturity (fair value of $489,217 and $568,208)	490,387	560,655
Loans held for sale	4,778	7,216
Loans	7,224,467	6,751,199
Less: Allowance for loan losses	(80,552)	(75,032)
Net Loans	7,143,915	6,676,167
Premises and equipment	93,420	95,852
Federal Home Loan Bank stock	24,588	23,825
Interest receivable	40,881	37,130
Other intangibles	24,429	31,148
Goodwill	445,355	445,355
Cash surrender value of life insurance	224,939	223,557
Other real estate owned	2,179	10,373
Tax asset, deferred and receivable	23,668	23,983
Other assets	47,772	42,338
TOTAL ASSETS	9,884,716	9,367,478
Deposits:
Noninterest-bearing	1,447,907	1,761,553
Interest-bearing	6,306,686	5,410,977
Total Deposits	7,754,593	7,172,530
Borrowings:
Federal funds purchased	104,000	144,038
Securities sold under repurchase agreements	113,512	136,623
Federal Home Loan Bank advances	314,986	414,377
Subordinated debentures and term loans	138,463	139,349
Total Borrowings	670,961	834,387
Interest payable	5,607	4,390
Other liabilities	45,295	52,708
Total Liabilities	8,476,456	8,064,015
COMMITMENTS AND CONTINGENT LIABILITIES
STOCKHOLDERS' EQUITY
Cumulative Preferred Stock	125	125
Common Stock	6,169	6,145
Additional paid-in capital	840,052	834,870
Retained earnings	583,336	465,231
Accumulated other comprehensive loss	(21,422)	(2,908)
Total Stockholders' Equity	1,408,260	1,303,463
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 9,884,716	$ 9,367,478

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Investment securities held to maturity	$ 489,217	$ 568,208
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
Common Stock, stated value (in dollars per share)	$ 0.125	$ 0.125
Common Stock, shares authorized	100,000,000	100,000,000
Common Stock, shares issued	49,349,800	49,158,238
Common Stock, shares outstanding	49,349,800	49,158,238

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loans receivable:
Taxable	$ 342,501	$ 263,704	$ 210,302
Tax exempt	14,862	10,694	6,525
Investment securities:
Taxable	21,597	17,489	16,415
Tax exempt	25,509	21,379	18,622
Deposits with financial institutions	2,241	736	350
Federal Reserve and Federal Home Loan Bank stock	1,234	894	1,098
Total Interest Income	407,944	314,896	253,312
INTEREST EXPENSE
Deposits	51,542	23,806	15,914
Federal funds purchased	718	561	102
Securities sold under repurchase agreements	762	477	374
Federal Home Loan Bank advances	7,832	5,196	3,264
Subordinated debentures and term loans	8,233	7,572	7,185
Total Interest Expense	69,087	37,612	26,839
NET INTEREST INCOME	338,857	277,284	226,473
Provision for loan losses	7,227	9,143	5,657
NET INTEREST INCOME AFTER PROVISION FOR LOAN LOSSES	331,630	268,141	220,816
OTHER INCOME
Increase in cash surrender value of life insurance	4,020	3,906	3,630
Gains on life insurance benefits	198	2,671	643
Net gains and fees on sales of loans	7,029	7,564	7,052
Net realized gains on sales of available for sale securities	4,269	2,631	3,389
Other income	5,192	2,970	3,594
Total Other Income	76,459	71,009	65,203
OTHER EXPENSES
Salaries and employee benefits	131,704	119,812	102,552
Net occupancy	18,341	16,976	16,997
Equipment	14,334	13,090	12,497
Marketing	4,681	3,739	3,008
Outside data processing fees	13,215	12,242	9,148
Printing and office supplies	1,425	1,283	1,348
Intangible asset amortization	6,719	5,647	3,910
FDIC assessments	2,920	2,564	3,036
Other real estate owned and foreclosure expenses	1,470	1,903	2,877
Professional and other outside services	8,176	12,757	6,516
Other expenses	16,966	15,543	15,470
Total Other Expenses	219,951	205,556	177,359
INCOME BEFORE INCOME TAX	188,138	133,594	108,660
Income tax expense	28,999	37,524	27,609
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 159,139	$ 96,070	$ 81,051
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS PER SHARE DATA:
Basic (in dollars per share)	$ 3.23	$ 2.13	$ 1.99
Diluted (in dollars per share)	$ 3.22	$ 2.12	$ 1.98
Service charges on deposit accounts
OTHER INCOME
OTHER INCOME	$ 20,950	$ 18,722	$ 17,762
Fiduciary activities
OTHER INCOME
OTHER INCOME	14,906	14,682	12,591
Other customer fees
OTHER INCOME
OTHER INCOME	$ 19,895	$ 17,863	$ 16,542

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 159,139	$ 96,070	$ 81,051
Other comprehensive income (loss) net of tax:
Unrealized holding gain (loss) on securities available for sale arising during the period, net of tax of $3,174, $5,193, and $4,893	(13,872)	9,645	(9,087)
Unrealized gain (loss) on cash flow hedges arising during the period, net of tax of $52, $4, and $128	437	9	(240)
Reclassification adjustment for net gains included in net income, net of tax of $797, $576, and $749	(3,002)	(1,070)	(1,390)
Defined benefit pension plans, net of tax of $1,001, $1,125, and $809
Net gain (loss) arising during period	(1,435)	2,686	(470)
Amortization of prior service cost	(16)	(597)	(1,032)
Period change	(17,888)	10,673	(12,219)
Comprehensive income	$ 141,251	$ 106,743	$ 68,832

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Unrealized holding gain (loss) on securities available for sale arising during the period, tax	$ (3,174)	$ 5,193	$ (4,893)
Unrealized gain (loss) on cash flow hedges arising during the period, tax	52	4	(128)
Reclassification adjustment for net losses (gains) included in net income, tax	797	576	749
Defined benefit pension plans, tax	$ 1,001	$ (1,125)	$ 809

CONSOLIDATED STATEMENT OF STOCK

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred	Common Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2015		125	40,664,259
Beginning balance at Dec. 31, 2015	$ 850,509	$ 125	$ 5,083	$ 504,530	$ 342,133	$ (1,362)
Comprehensive income
Net income	81,051				81,051
Other comprehensive income (loss), net of tax	(12,219)					(12,219)
Cash dividends on common stock	(22,203)				(22,203)
Issuance of common stock related to acquisition
Share-based compensation (in shares)			141,126
Share-based compensation	2,600		$ 17	2,583
Stock Issued under employee benefit plans (in shares)			20,545
Stock issued under employee benefit plans	462		$ 3	459
Stock issued under dividend reinvestment and stock purchase plan (in shares)			30,297
Stock issued under dividend reinvestment and stock purchase plan	835		$ 4	831
Stock options exercised (in shares)			128,848
Stock options exercised	2,602		$ 16	2,586
Stock redeemed (in shares)			(72,378)
Stock redeemed	(1,980)		$ (9)	(1,971)
Ending balance (in shares) at Dec. 31, 2016		125	40,912,697
Ending balance at Dec. 31, 2016	901,657	$ 125	$ 5,114	509,018	400,981	(13,581)
Comprehensive income
Net income	96,070				96,070
Other comprehensive income (loss), net of tax	10,673					10,673
Cash dividends on common stock	(31,820)				(31,820)
Issuance of common stock related to acquisition (in shares)			8,044,446
Issuance of common stock related to acquisition	321,431		$ 1,006	320,425
Share-based compensation (in shares)			89,362
Share-based compensation	2,827		$ 11	2,816
Stock Issued under employee benefit plans (in shares)			14,948
Stock issued under employee benefit plans	519		$ 2	517
Stock issued under dividend reinvestment and stock purchase plan (in shares)			24,058
Stock issued under dividend reinvestment and stock purchase plan	991		$ 3	988
Stock options exercised (in shares)			104,748
Stock options exercised	2,398		$ 13	2,385
Stock redeemed (in shares)			(32,021)
Stock redeemed	(1,283)		$ (4)	(1,279)
Ending balance (in shares) at Dec. 31, 2017		125	49,158,238
Ending balance at Dec. 31, 2017	1,303,463	$ 125	$ 6,145	834,870	465,231	(2,908)
Comprehensive income
Net income	159,139				159,139
Other comprehensive income (loss), net of tax	(17,888)					(17,888)
Cash dividends on common stock	(41,660)				(41,660)
Reclassification adjustment under ASU 2018-02	0				626	(626)
Issuance of common stock related to acquisition
Share-based compensation (in shares)			112,569
Share-based compensation	3,592		$ 14	3,578
Stock Issued under employee benefit plans (in shares)			19,001
Stock issued under employee benefit plans	707		$ 2	705
Stock issued under dividend reinvestment and stock purchase plan (in shares)			28,156
Stock issued under dividend reinvestment and stock purchase plan	$ 1,211		$ 4	1,207
Stock options exercised (in shares)	76,152		76,152
Stock options exercised	$ 1,598		$ 10	1,588
Stock redeemed (in shares)			(44,316)
Stock redeemed	(1,902)		$ (6)	(1,896)
Ending balance (in shares) at Dec. 31, 2018		125	49,349,800
Ending balance at Dec. 31, 2018	$ 1,408,260	$ 125	$ 6,169	$ 840,052	$ 583,336	$ (21,422)

CONSOLIDATED STATEMENT OF STO_2

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Cash dividends on common stock (in dollars per share)	$ 0.84	$ 0.69	$ 0.54

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flow From Operating Activities:
Net income	$ 159,139	$ 96,070	$ 81,051
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	7,227	9,143	5,657
Depreciation and amortization	8,842	7,967	7,161
Change in deferred taxes	3,524	15,523	8,611
Share-based compensation	3,592	2,827	2,600
Loans originated for sale	(372,791)	(377,252)	(354,265)
Proceeds from sales of loans held for sale	380,254	387,095	367,148
Gains on sales of loans held for sale	(5,025)	(5,910)	(5,918)
Gains on sales of securities available for sale	(4,269)	(2,631)	(3,389)
Increase in cash surrender of life insurance	(4,020)	(3,906)	(3,630)
Gains on life insurance benefits	(198)	(2,671)	(643)
Change in interest receivable	(3,751)	(6,838)	(1,779)
Change in interest payable	1,217	31	18
Other adjustments	6,494	7,054	1,097
Net cash provided by operating activities	180,235	126,502	103,719
Cash Flows from Investing Activities:
Net change in interest-bearing deposits	(1,936)	237,936	7,856
Purchases of:
Securities available for sale	(370,284)	(479,045)	(281,470)
Securities held to maturity	(30,465)	(30,220)	(110,797)
Proceeds from sales of securities available for sale	154,519	94,165	167,186
Proceeds from maturities of:
Securities available for sale	77,881	70,846	73,956
Securities held to maturity	66,129	72,220	119,052
Redemption (Purchase) of Federal Reserve and Federal Home Loan Bank stock	(763)	40	19,669
Net change in loans	(483,418)	(670,000)	(452,781)
Net cash and cash equivalents received in acquisition		54,536
Proceeds from the sale of other real estate owned	9,121	6,584	9,974
Proceeds from life insurance benefits	2,836	11,655	3,141
Other investing activities	804	(4,047)	(4,490)
Net cash used in investing activities	(575,576)	(635,330)	(448,704)
Net change in :
Demand and savings deposits	526,859	425,742	332,600
Certificates of deposit and other time deposits	55,204	75,236	(66,920)
Borrowings	1,515,526	1,088,189	1,107,795
Repayment of borrowings	(1,677,860)	(1,024,166)	(982,449)
Cash dividends on common stock	(41,660)	(31,820)	(22,203)
Stock issued under employee benefit plans	707	519	462
Stock issued under dividend reinvestment and stock purchase plans	1,211	991	835
Stock options exercised	1,598	2,398	2,602
Stock redeemed	(1,902)	(1,283)	(1,980)
Net cash provided by financing activities	379,683	535,806	370,742
Net Change in Cash and Cash Equivalents	(15,658)	26,978	25,757
Cash and Cash Equivalents, beginning of the year	154,905	127,927	102,170
Cash and Cash Equivalents, end of year	139,247	154,905	127,927
Additional cash flow information:
Interest paid	67,870	36,332	26,821
Income tax paid	23,289	22,421	11,999
Loans transferred to other real estate owned	855	8,360	1,684
Fixed assets transferred to other assets	374	6,753	360
Non-cash investing activities using trade date accounting	6,551	9,401	14,179
Investments transferred from held to maturity to available for sale in accordance with ASU 2017-12	30,794
Liabilities assumed in conjunction with acquisitions
Fair value of assets acquired	0	1,531,397	0
Cash received (paid) in acquisition		(12)
Less: Common stock issued		321,431
Liabilities assumed	$ 0	$ 1,209,954	$ 0

Nature of Operations and Summar

Nature of Operations and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Nature of Operations and Summary of Significant Accounting Policies	NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Financial Statement Preparation The accounting and reporting policies of the Corporation and the Bank, conform to accounting principles generally accepted in the United States of America and reporting practices followed by the banking industry. 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 provides full banking services under an Indiana state-charter. Additionally, the Bank operates as First Merchants Private Wealth Advisors (a division of First Merchants Bank). The Bank generates commercial, mortgage, and consumer loans and receives deposits from customers located primarily in central and northern 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 OTTI at least on a quarterly basis, and more frequently when economic or market conditions warrant such an evaluation. In determining OTTI, 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 an other-than-temporary decline exists involves a high degree of subjectivity and judgment and is based on the information available to management at a point in time. When OTTI occurs, the amount of OTTI recognized in the income statement depends on whether the Corporation intends to sell the security 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. 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 shall be 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. If the intent is not to sell the security and it is not more likely than not that the Corporation will be required to sell the security before the recovery of its amortized cost basis less any recognized credit loss, the OTTI has been separated into the amount representing the credit loss and the amount related to all other factors. 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 is 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. 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 loan portfolio are carried at the principal amount outstanding, net of unearned income and principal charge-offs. Certain non-accrual, substantially delinquent and renegotiated loans classified as troubled debt restructures may be considered to be impaired in accordance with ASC 310, Receivables . Under ASC 310-10, a loan is impaired when, based on current information or events, it is probable all amounts due (principal and interest) according to the contractual terms of the loan agreement are uncollectible. Renegotiated consumer loans classified as troubled debt restructures are considered to be impaired. In applying the provisions of ASC 310-10, the Corporation considers all other investments in one-to-four family residential loans and consumer installment loans to be homogeneous and therefore excluded from separate identification for evaluation of impairment. Impaired loans are carried at the fair value of collateral if the loan is collateral dependent, or the present value of estimated future cash flows using the loan’s existing rate. 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. Interest income is accrued on the principal balances of loans. The accrual of interest is discontinued on a loan when, in management’s opinion, the borrower may be unable to meet payments as they become due. When the interest accrual is discontinued, all unpaid accrued interest is reversed against earnings when considered uncollectible. 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. Loan commitments and letters-of-credit generally have short-term, variable-rate features and contain clauses which limit the 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 purchased credit impaired. Evidence of credit quality deterioration as of purchase dates may include information such as past-due and nonaccrual status, borrower credit risk grade and recent loan to value percentages. Purchased 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 individually evaluated for the initial fair value measurement. Accordingly, allowances for credit losses related to these loans are not carried over at the acquisition date. 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. Acquired loans not accounted for under ASC 310-30 are accounted for under ASC 310-20, which allows the fair value adjustment to be accreted into income over the remaining life of the loans. 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 is confirmed. Subsequent recoveries, if any, are credited to the allowance. The Corporation’s strategy for credit risk management includes 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 regional geographic and industry levels, 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 impaired loans accounted for under ASC 310-10, 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. 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. Loans individually evaluated for impairment are those deemed impaired in accordance with ASC 310-10, including commercial relationships greater than $500,000 that exhibit well defined credit weaknesses. Any allowances for impaired loans are measured based on the fair value of the underlying collateral if collateral dependent or the present value of expected future cash flows discounted at the loan’s effective interest rate. The Corporation evaluates the collectability of principal 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 20. PENSION AND OTHER POST RETIREMENT BENEFIT PLANS of these Notes to Consolidated Financial Statements. 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 HOME LOAN BANK STOCK is a required investment for institutions that are members of the FHLB. The Bank is a member of the FHLB of Indianapolis. Members are required to own a certain amount of stock based on the level of borrowings and other factors, and may invest in additional amounts. FHLB stock is 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 two 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, Intangibles – Goodwill and Other . 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, 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 to offset a portion of the employee benefit costs. 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. Changes in cash surrender values and death benefits received in excess of cash surrender values are reported in non-interest income. A corporate policy is in place with defined thresholds that limit the amount of credit, interest rate and liquidity risk inherent in a BOLI portfolio. The Corporation actively monitors the overall portfolio performance along with the credit quality of the insurance carriers and the credit quality and yield of the underlying investments. 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 other real estate owned and foreclosure expenses. 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 AOCI 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: (1) a hedge of the fair value of the recognized asset or liability or of an unrecognized firm commitment (a fair value hedge); or (2) 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 AOCI to the extent the hedge is effective. The gains and losses on derivative instruments that are reported in AOCI 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 in the consolidated statements of income. 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, Fair Value Measurements and Disclosures ), resulting in some volatility in earnings each period. SECURITIES SOLD UNDER REPURCHASE AGREEMENTS represent securities the Corporation routinely sells to certain treasury management customers and then repurchases these securities the next day. Securities sold under repurchase agreements are reflected as secured borrowings in the consolidated balance sheets at the amount of cash received in connection with each transaction. 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 is generally no longer subject to U.S. federal, state and local income tax examinations by tax authorities for tax years before 2015 . 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 Corporation's policy is to recognize interest and penalties related to unrecognized tax benefits, if any, as a component of income tax expense. 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. Recent Accounting Changes ASU 2018-02 "Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income" ("ASU 2018-02") allows a reclassification from accumulated other comprehensive income (loss) to retained earnings for the stranded tax effects caused by the revaluation of deferred taxes resulting from the newly enacted corporate tax rate in the Tax Cuts and Jobs Act. The ASU is effective in years beginning after December 15, 2018, but permits early adoption in a period for which financial statements have not yet been issued. The Corporation elected to early adopt the ASU as of January 1, 2018. The adoption of the guidance resulted in an insignificant cumulative-effect adjustment that decreased accumulated other comprehensive income (loss) and increased retained earnings in 2018. ASU 2017-12 - "Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities" ("ASU 2017-12") is intended to improve and simplify accounting rules around hedge accounting. The ASU is effective for public companies in 2019 and private companies in 2020. Early adoption is permitted. The new standard refines and expands hedge accounting for both financial (e.g., interest rate) and commodity risks. Its provisions create more transparency around how economic results are presented, both on the face of the financial statements and in the footnotes, for investors and analysts. The new standard takes effect for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, for public companies and for fiscal years beginning after December 15, 2019 (and interim periods for fiscal years beginning after December 15, 2020), for private companies. Early adoption is permitted in any interim period or fiscal years before the effective date of the standard. ASU 2017-12 requires a modified retrospective transition method in which a cumulative effect of the change on the opening balance of each affected component of equity is recognized in the statement of financial position as of the date of adoption. The Corporation adopted this standard in the third quarter of 2018. As permitted by the ASU, the Corporation reclassified $30.8 million of state and municipal securities with unrealized gains of $450,000 from the held to maturity portfolio to the available for sale portfolio. Other than this reclassification of securities, adoption of the standard did not have a significant impact on the Corporation’s consolidated financial statements. ASU 2017-07 " Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost" ("ASU 2017-07") applies to all employers, including not-for-profit entities, that offer to their employees defined benefit pension plans, other postretirement benefit plans, or other types of benefits accounted for under Topic 715, Compensation - Retirement Benefits . The amendments require that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. If a separate line item or items are used to present the other components of net benefit cost, that line item or items must be appropriately described. If a separate line item or items are not used, the line item or items used in the income statement to present the other components of net benefit cost must be disclosed. The amendments also allow only the service cost component to be eligible for capitalization when applicable (e.g., as a cost of internally manufactured inventory or a self-constructed asset). The amendments are effective for public business entities for annual periods beginning after December 15, 2017, including interim periods within those annual periods. For other entities, the amendments are effective for annual periods beginning after December 15, 2018, and interim periods within annual periods beginning after December 15, 2019. Early adoption is permitted as of the beginning of an annual period for which financial statements (interim or annual) have not been issued or made available for issuance. The Corporation adopted this ASU in 2018. Adoption of the standard did not have a significant impact on the Corporation’s consolidated financial statements. ASU 2016-15 "Statement of Cash Flows (Topic 230)" ("ASU 2016-15") is intended to reduce the diversity in practice around how certain transactions are classified within the statement of cash flows. ASU 2016-15 became effective for the Corporation on January 1, 2018 and did not have a significant impact on the Corporation's financial statements. ASU 2016-01 "Financial Instruments - Overall (Subtopic 825-10): Recognition of Financial Assets and Financial Liabilities" ("ASU 2016-01") makes targeted amendments to the guidance for recognition, measurement, presentation and disclosure of financial instruments. ASU 2016-01 requires equity investments, other than equity method investments, to be measured at fair value with changes in fair value recognized in net income. The ASU requires a cumulative-effect adjustment to retained earnings as of the beginning of the reporting period of adoption to reclassify the cumulative change in fair value of equity securities previously recognized in accumulated other comprehensive income (loss). ASU 2016-01 became effective for the Corporation on January 1, 2018. The adoption of the guidance did not result in any cumulative effect adjustment in 2018. ASU 2016-01 also emphasizes the existing requirement to use exit prices to measure fair value for disclosure purposes and clarifies that entities should not make use of a practicability exception in determining the fair value of loans. Accordingly, the Corporation refined the calculation used to determine the disclosed fair value of loans held for investment as part of adopting this standard. The refined calculation did not have a significant impact on the fair value disclosures included in NOTE 14. FAIR VALUE OF FINANCIAL INSTRUMENTS of these Notes to Consolidated Condensed Financial Statements. ASU 2014-09 "Revenue from Contracts with Customers (Topic 606)" ("ASU 2014-09") implements a common revenue standard

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisitions	ACQUISITIONS Independent Alliance Banks, Inc. On November 21, 2016, the Corporation purchased 495,112 shares, or 12.1 percent, of IAB's outstanding common stock from an IAB shareholder for $19.8 million , or $40.00 per share. On July 14, 2017, the Corporation acquired the remaining shares of IAB common stock. IAB, an Indiana Corporation, merged with and into the Corporation, whereupon the separate corporate existence of IAB ceased and the Corporation survived. Immediately following the merger, IAB's wholly-owned subsidiary, iAB Financial Bank, merged with and into the Bank, with the Bank continuing as the surviving bank. IAB was headquartered in Fort Wayne, Indiana and had 16 banking centers serving the Fort Wayne market. Pursuant to the merger agreement, each IAB shareholder received 1.653 shares of the Corporation's common stock for each outstanding share of IAB common stock held. The Corporation issued approximately 6.0 million shares of common stock. The transaction value for the remaining shares of common stock, not owned by the Corporation, was approximately $238.8 million , resulting in a total purchase price of $258.6 million . The Corporation engaged in this transaction with the expectation that it would be accretive to income 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 and economies of scale. In the third quarter of 2017, ASC 805-10 - Business Combinations, required the Corporation to remeasure the 12.1 percent equity interest in IAB's common stock and recognize the resulting gain or loss, if any, in earnings. The remeasurement was based upon the closing price of IAB's common stock immediately prior to the acquisition announcement, and prior to the Corporation obtaining control of IAB. The trading price of IAB's common stock subsequent to the acquisition announcement included a control or acquisition premium and was not indicative of the fair value of the Corporation's pre-existing equity interest immediately prior to the acquisition announcement. The fair value of the equity interest in IAB's common stock after the remeasurement was $19.8 million. The Corporation recorded a $50,000 loss in 2017 as a result of the remeasurement and the loss is reflected in the Corporation's Consolidated Statements of Income in the line titled "Net realized gains on sales of available for sale securities." 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 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 IAB acquisition is detailed in the following table. Fair Value Cash and cash equivalents $ 6,016 Interest-bearing time deposits 248,212 Investment securities 4,078 Loans held for sale 594 Loans 725,382 Premises and equipment 10,107 Federal Home Loan Bank stock 4,810 Interest receivable 3,445 Cash surrender value of life insurance 26,964 Other assets 11,780 Deposits (862,271 ) Securities sold under repurchase agreements (17,915 ) Federal Home Loan Bank Advances (47,575 ) Subordinated debentures (10,583 ) Interest payable (1,005 ) Other liabilities (14,472 ) Net tangible assets acquired 87,567 Other Intangible assets 17,403 Goodwill 153,636 Purchase price $ 258,606 Of the total purchase price, $17,403,000 has been allocated to other intangible assets. Approximately $13.6 million was allocated to a core deposit intangible, which will be amortized over its estimated life of 10 years. Approximately $3.8 million was allocated to a non-compete intangible, which will be amortized over its estimated life of 2 years. The remaining purchase price was allocated to goodwill, which is not deductible for tax purposes. Acquired loan data for IAB can be found in the table below: Fair Value of Acquired Loans at Acquisition Date Gross Contractual Amounts Receivable at Acquisition Date Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected Acquired receivables subject to ASC 310-30 $ 4,838 $ 14,131 $ 8,352 Acquired receivables not subject to ASC 310-30 $ 720,544 $ 864,613 $ 9,786 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 difference. 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. The Arlington Bank On May 19, 2017, the Corporation acquired 100 percent of Arlington Bank. Arlington Bank, an Ohio savings bank, merged with and into the Bank, with the Bank continuing as the surviving bank. Arlington Bank was headquartered in Columbus, Ohio and had 3 banking centers serving the Columbus, Ohio market. Pursuant to the merger agreement, each Arlington Bank shareholder received 2.7245 shares of the Corporation's common stock for each outstanding share of Arlington Bank common stock held. The Corporation issued approximately 2.1 million shares of common stock, which was valued at approximately $82.6 million. The Corporation engaged in this transaction with the expectation that it would be accretive to income and expand the existing footprint in Columbus, Ohio. Goodwill resulted from this transaction due to the expected synergies and economies of scale. 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 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 Arlington Bank acquisition is detailed in the following table. Fair Value Cash and cash equivalents $ 48,532 Interest-bearing time deposits 292 Loans held for sale 7,626 Loans 224,680 Premises and equipment 1,986 Federal Home Loan Bank stock 1,091 Interest receivable 653 Other assets 1,620 Deposits (252,783 ) Interest payable (244 ) Other liabilities (3,106 ) Net tangible assets acquired 30,347 Core deposit intangible 4,526 Goodwill 47,719 Purchase price $ 82,592 Of the total purchase price, $4,526,000 has been allocated to a core deposit intangible that will be amortized over its estimated life of 10 years. The remaining purchase price was allocated to goodwill, which is not deductible for tax purposes. Acquired loan data for Arlington Bank can be found in the table below: Fair Value of Acquired Loans at Acquisition Date Gross Contractual Amounts Receivable at Acquisition Date Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected Acquired receivables subject to ASC 310-30 $ 2,625 $ 6,183 $ 2,891 Acquired receivables not subject to ASC 310-30 $ 222,055 $ 308,857 $ 2,741 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 difference. 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. Pro Forma Financial Information The results of operations of Arlington Bank and IAB have been included in the Corporation's consolidated financial statements since the acquisition dates. The following schedule includes pro forma results for the year ended December 31, 2017 and 2016, as if the Arlington Bank and IAB acquisitions occurred as of the beginning of the periods presented. 2017 2016 Total revenue (net interest income plus other income) $ 380,324 $ 353,732 Net income available to common shareholders $ 95,009 $ 95,288 Earnings per share: Basic $ 1.94 $ 1.95 Diluted $ 1.93 $ 1.94 The pro forma information includes adjustments for interest income on loans, interest expense on deposits and borrowings, premises expense for the banking centers acquired and amortization of intangibles arising from the transaction and the related income tax effects. The pro forma information for the year ended December 31, 2017 includes operating revenue of $9.0 million and $21.4 million from Arlington Bank and IAB acquisitions since the date of acquisition, respectively. Additionally, $15.4 million, net of tax, of expenses directly attributable to the Arlington Bank and IAB acquisitions were included in the year ended December 31, 2017 pro forma information. The pro forma information for the year ended December 31, 2016 includes operating results from Arlington Bank and IAB as if the acquisitions occurred at the beginning of the year. The pro forma information is presented for information purposes only and is not indicative of the results of operations that actually would have been achieved had the acquisitions been consummated as of that time, nor is it intended to be a projection of future results.

Cash and Cash Equivalents

Cash and Cash Equivalents	12 Months Ended
	Dec. 31, 2018
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents	CASH AND CASH EQUIVALENTS The Corporation considers all liquid investments with original maturities of three months or less to be cash equivalents. As of December 31, 2018 , cash and cash equivalents is defined to include cash on hand, deposits in other institutions and federal funds sold. At December 31, 2018 , the Corporation’s interest-bearing cash accounts and noninterest-bearing transaction deposits held at other institutions exceeded the $250,000 federally insured limits by approximately $122,092,000 . 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 $7,639,000 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, 2018 , was $45,352,000 .

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2018
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, 2018 U.S. Government-sponsored agency securities $ 13,493 $ 92 $ 3 $ 13,582 State and municipal 605,994 5,995 5,854 606,135 U.S. Government-sponsored mortgage-backed securities 530,209 634 8,396 522,447 Corporate obligations 31 31 Total available for sale 1,149,727 6,721 14,253 1,142,195 Held to maturity at December 31, 2018 U.S. Government-sponsored agency securities 22,618 545 22,073 State and municipal 197,909 2,858 872 199,895 U.S. Government-sponsored mortgage-backed securities 268,860 713 3,323 266,250 Foreign investment 1,000 1 999 Total held to maturity 490,387 3,571 4,741 489,217 Total Investment Securities $ 1,640,114 $ 10,292 $ 18,994 $ 1,631,412 Available for sale at December 31, 2017 U.S. Government-sponsored agency securities State and municipal $ 510,852 $ 16,932 $ 1,091 $ 526,693 U.S. Government-sponsored mortgage-backed securities 473,325 964 3,423 470,866 Corporate obligations 31 31 Equity securities 2,357 2,357 Total available for sale 986,565 17,896 4,514 999,947 Held to maturity at December 31, 2017 U.S. Government-sponsored agency securities 22,618 435 22,183 State and municipal 235,594 6,295 244 241,645 U.S. Government-sponsored mortgage-backed securities 301,443 3,341 1,404 303,380 Foreign investment 1,000 1,000 Total held to maturity 560,655 9,636 2,083 568,208 Total Investment Securities $ 1,547,220 $ 27,532 $ 6,597 $ 1,568,155 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 $951,571,000 and $452,644,000 at December 31, 2018 and 2017 , respectively. Total fair value of these investments was $932,577,000 and $446,047,000 , which was approximately 57.1 and 28.6 percent of the Corporation's available for sale and held to maturity investment portfolio at December 31, 2018 and 2017 , 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, 2018 . 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, 2018 . As noted in the table above, the mortgage-backed securities portfolio contains unrealized losses of $8,396,000 on one hundred five securities and $3,323,000 on seventy-six 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, U.S. Government-Sponsored Agency Securities and Foreign Investment Securities The unrealized losses on the Corporation's investments in securities of state and political subdivisions, U.S. Government-Sponsored Agency and foreign investment securities 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, 2018 . As noted in the table above, the state and municipal securities portfolio contains unrealized losses of $5,854,000 on two hundred twenty-one securities and $872,000 on forty-one securities in the available for sale and held to maturity portfolios, respectively. The U.S. Government-Sponsored Agency securities portfolio contains unrealized losses of $3,000 on four securities in the available for sale portfolio, and $545,000 on five securities in the held to maturity portfolio. The foreign investment securities portfolio contains no unrealized losses in the available for sale portfolio, and $1,000 on one security in the held to maturity portfolio. 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, 2018 and 2017 : Less than 12 Months 12 Months or Longer Total Fair Gross Fair Gross Fair Gross Temporarily Impaired Available for Sale Securities at December 31, 2018 U.S. Government-sponsored agency securities $ 1,490 $ 3 $ 1,490 $ 3 State and municipal 234,431 3,958 $ 38,028 $ 1,896 272,459 5,854 U.S. Government-sponsored mortgage-backed securities 196,601 2,400 217,121 5,996 413,722 8,396 Total Temporarily Impaired Available for Sale Securities 432,522 6,361 255,149 7,892 687,671 14,253 Temporarily Impaired Held to Maturity Securities at December 31, 2018 U.S. Government-sponsored agency securities 22,073 545 22,073 545 State and municipal 14,952 369 16,786 503 31,738 872 U.S. Government-sponsored mortgage-backed securities 102,828 876 87,268 2,447 190,096 3,323 Foreign investment 999 1 999 1 Total Temporarily Impaired Held to Maturity Securities 117,780 1,245 127,126 3,496 $ 244,906 4,741 Total Temporarily Impaired Investment Securities $ 550,302 $ 7,606 $ 382,275 $ 11,388 $ 932,577 $ 18,994 Less than 12 Months 12 Months or Longer Total Fair Gross Fair Gross Fair Gross Temporarily Impaired Available for Sale Securities at December 31, 2017 State and municipal $ 13,296 $ 198 $ 35,324 $ 893 $ 48,620 $ 1,091 U.S. Government-sponsored mortgage-backed securities 182,755 1,520 68,667 1,903 251,422 3,423 Total Temporarily Impaired Available for Sale Securities 196,051 1,718 103,991 2,796 300,042 4,514 Temporarily Impaired Held to Maturity Securities at December 31, 2017 U.S. Government-sponsored agency securities 9,988 131 12,196 304 22,184 435 State and municipal 2,430 36 15,805 208 18,235 244 U.S. Government-sponsored mortgage-backed securities 62,508 485 43,078 919 105,586 1,404 Total Temporarily Impaired Held to Maturity Securities 74,926 652 71,079 1,431 146,005 2,083 Total Temporarily Impaired Investment Securities $ 270,977 $ 2,370 $ 175,070 $ 4,227 $ 446,047 $ 6,597 The amortized cost and fair value of securities available for sale and held to maturity at December 31, 2018 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, 2018 Due in one year or less $ 13,092 $ 13,144 $ 4,732 $ 4,730 Due after one through five years 5,311 5,378 49,054 48,473 Due after five through ten years 73,280 74,411 62,873 64,163 Due after ten years 527,835 526,815 104,868 105,601 619,518 619,748 221,527 222,967 U.S. Government-sponsored mortgage-backed securities 530,209 522,447 268,860 266,250 Total Investment Securities $ 1,149,727 $ 1,142,195 $ 490,387 $ 489,217 Securities with a carrying value of approximately $416,155,000 , $475,999,000 and $572,896,000 were pledged at December 31, 2018 , 2017 and 2016 , respectively, to secure certain deposits and securities sold under repurchase agreements, and for other purposes as permitted or required by law. The book value of securities sold under agreements to repurchase amounted to $116,691,000 at December 31, 2018, and $136,639,000 at December 31, 2017. Gross gains of $4,269,000 , $2,681,000 and $3,389,000 were realized on sales of investment securities in 2018 , 2017 and 2016 , respectively. Gross losses of $50,000 were realized on sales of investment securities in 2017 . There were no losses from the sales of investment securities in 2018 or 2016 , respectively.

Loans and Allowance

Loans and Allowance	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Loans and Allowance	LOANS AND ALLOWANCE The Corporation's primary lending focus is small business and middle market commercial, commercial real estate and residential real estate, which results in portfolio diversification. The following tables show the composition of the loan portfolio, the allowance for loan losses and credit quality characteristics by collateral classification, excluding loans held for sale. Loans held for sale at December 31, 2018 and 2017 , were $4,778,000 and $7,216,000 , respectively. The following table illustrates the composition of the Corporation’s loan portfolio by loan class for the years indicated: December 31, 2018 December 31, 2017 Commercial and industrial loans $ 1,726,664 $ 1,493,493 Agricultural production financing and other loans to farmers 92,404 121,757 Real estate loans: Construction 545,729 612,219 Commercial and farmland 2,832,102 2,562,691 Residential 966,421 962,765 Home equity 528,157 514,021 Individuals' loans for household and other personal expenditures 99,788 86,935 Lease financing receivables, net of unearned income 1,600 2,527 Other commercial loans 431,602 394,791 Loans 7,224,467 6,751,199 Allowance for loan losses (80,552 ) (75,032 ) Net Loans $ 7,143,915 $ 6,676,167 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, 2018 . 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 it 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, portfolio mix and collateral values. The allowance for loan losses is maintained through the provision for loan losses, which is a charge against earnings. The allowance is increased by provision expense and decreased by charge-offs less recoveries. All charge-offs are approved by the Bank's senior credit officers and in accordance with established policies. The Bank charges off a loan when a determination is made that all or a portion of the loan is uncollectible. 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 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. 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 450 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. 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 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 ensure that losses inherent in the portfolio are reflected in the allowance for loan losses. The environmental component adjusts the historical loss allocations for non-impaired 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. 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 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. At December 31, 2018, the allowance for loan losses was $80,552,000 , an increase of $5,520,000 from the December 31, 2017 balance of $75,032,000 . Net charge-offs for the twelve months ended December 31, 2018, were $1,707,000 , an increase of $1,559,000 from the same period in 2017. The provision for loan losses for the twelve months ended December 31, 2018 was $7,227,000 , a decrease of $1,916,000 from the same period in 2017. 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 tables summarize changes in the allowance for loan losses by loan segment for the twelve months ended December 31, 2018, 2017, and 2016: Twelve Months Ended December 31, 2018 Commercial Commercial Real Estate Consumer Residential Finance Total Allowance for loan losses: Balances, December 31, 2017 $ 30,418 $ 27,343 $ 3,732 $ 13,537 $ 2 $ 75,032 Provision for losses 2,097 2,482 679 1,969 7,227 Recoveries on loans 2,456 2,525 302 993 6,276 Loans charged off (2,316 ) (2,741 ) (749 ) (2,177 ) (7,983 ) Balances, December 31, 2018 $ 32,655 $ 29,609 $ 3,964 $ 14,322 $ 2 $ 80,552 Twelve Months Ended December 31, 2017 Commercial Commercial Real Estate Consumer Residential Finance Total Allowance for loan losses: Balances, December 31, 2016 $ 27,696 $ 23,661 $ 2,923 $ 11,755 $ 2 $ 66,037 Provision for losses 2,515 3,159 1,078 2,391 9,143 Recoveries on loans 1,590 2,260 324 706 4,880 Loans charged off (1,383 ) (1,737 ) (593 ) (1,315 ) (5,028 ) Balances, December 31, 2017 $ 30,418 $ 27,343 $ 3,732 $ 13,537 $ 2 $ 75,032 Twelve Months Ended December 31, 2016 Commercial Commercial Real Estate Consumer Residential Finance Total Allowance for loan losses: Balances, December 31, 2015 $ 26,478 $ 22,145 $ 2,689 $ 11,139 $ 2 $ 62,453 Provision for losses 1,876 1,834 432 1,515 5,657 Recoveries on loans 1,806 2,090 369 1,091 5,356 Loans charged off (2,464 ) (2,408 ) (567 ) (1,990 ) (7,429 ) Balances, December 31, 2016 $ 27,696 $ 23,661 $ 2,923 $ 11,755 $ 2 $ 66,037 The tables below show the Corporation’s allowance for loan losses and loan portfolio by loan segment for the years indicated. At December 31, 2018 and 2017, there was no related allowance for loan losses for loans acquired with deteriorated credit quality. December 31, 2018 Commercial Commercial Consumer Residential Finance Total Allowance balances: Individually evaluated for impairment $ 1,435 $ 1 $ 436 $ 1,872 Collectively evaluated for impairment $ 32,655 28,174 3,963 13,886 $ 2 78,680 Total allowance for loan losses $ 32,655 $ 29,609 $ 3,964 $ 14,322 $ 2 $ 80,552 Loan balances: Individually evaluated for impairment $ 1,838 $ 17,756 $ 18 $ 2,413 $ 22,025 Collectively evaluated for impairment 2,246,730 3,347,686 99,770 1,490,872 $ 1,600 7,186,658 Loans acquired with deteriorated credit quality 2,102 12,389 1,293 15,784 Loans $ 2,250,670 $ 3,377,831 $ 99,788 $ 1,494,578 $ 1,600 $ 7,224,467 December 31, 2017 Commercial Commercial Consumer Residential Finance Total Allowance balances: Individually evaluated for impairment $ 666 $ 567 $ 404 $ 1,637 Collectively evaluated for impairment 29,752 26,776 $ 3,732 13,133 $ 2 73,395 Total allowance for loan losses $ 30,418 $ 27,343 $ 3,732 $ 13,537 $ 2 $ 75,032 Loan balances: Individually evaluated for impairment $ 3,345 $ 17,432 $ 5 $ 2,429 $ 23,211 Collectively evaluated for impairment 2,005,275 3,135,481 86,930 1,472,821 $ 2,527 6,703,034 Loans acquired with deteriorated credit quality 1,421 21,997 1,536 24,954 Loans $ 2,010,041 $ 3,174,910 $ 86,935 $ 1,476,786 $ 2,527 $ 6,751,199 Loans individually evaluated for impairment are comprised of commercial and consumer loans deemed impaired in accordance with ASC 310-10 and include loans acquired with deteriorated credit quality totaling $1,541,000 and $315,000 at December 31, 2018 and 2017, respectively. The risk characteristics of the Corporation’s material portfolio segments are as follows: Commercial Commercial lending is 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 tangible assets being financed such as equipment or real estate or other business assets such as accounts receivable or inventory and may incorporate a personal guarantee. Other loans may be unsecured, secured but under-collateralized or otherwise made on the basis of the enterprise value of an organization. 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. Consumer and Residential With respect to residential loans that are secured by 1-4 family residences, which 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 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, such as small installment loans and certain lines of credit, are unsecured . 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 on loans secured by 1-4 family residences can be impacted by changes in property values. 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. When the interest accrual is discontinued, all unpaid accrued interest is reversed against earnings when considered uncollectible. 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: December 31, 2018 December 31, 2017 Commercial and industrial loans $ 1,803 $ 3,275 Agriculture production financing and other loans to farmers 679 1,027 Real estate loans: Construction 8,667 65 Commercial and farmland 8,156 12,951 Residential 4,966 9,444 Home equity 1,481 1,928 Individuals' loans for household and other personal expenditures 42 34 Other commercial loans 354 Total $ 26,148 $ 28,724 Impaired loans include loans deemed impaired according to the guidance set forth in ASC 310-10. Commercial loans under $500,000 and consumer loans, with the exception of troubled debt restructures, are not individually evaluated for impairment. 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 for measuring the amount of impairment is utilized. This method requires obtaining a current independent appraisal of the collateral and applying a discount factor, which includes selling costs if applicable, 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 impaired loans, related allowance and interest income recognized while impaired by loan class for the years indicated: December 31, 2018 Unpaid Principal Recorded Related Average Recorded Investment Interest Income Recognized Impaired loans with no related allowance: Commercial and industrial loans $ 828 $ 806 $ 833 Agriculture production financing and other loans to farmers 679 679 679 Real estate loans: Construction 1,352 614 835 Commercial and farmland 11,176 8,994 12,975 $ 165 Residential 118 100 101 3 Home equity 49 48 48 Other commercial loans 353 353 353 Total $ 14,555 $ 11,594 $ 15,824 $ 168 Impaired loans with related allowance: Real estate loans: Construction $ 7,978 $ 7,977 $ 1,429 $ 7,977 Commercial and farmland 171 171 6 171 Residential 1,958 1,907 362 1,915 57 Home equity 376 358 74 365 10 Individuals' loans for household and other personal expenditures 18 18 1 20 $ 1 Total $ 10,501 $ 10,431 $ 1,872 $ 10,448 $ 68 Total Impaired Loans $ 25,056 $ 22,025 $ 1,872 $ 26,272 $ 236 December 31, 2017 Unpaid Principal Recorded Related Average Recorded Investment Interest Income Recognized Impaired loans with no related allowance: Commercial and industrial loans $ 7,611 $ 1,536 $ 3,839 Agriculture production financing and other loans to farmers 732 700 762 Real estate loans: Commercial and farmland 16,758 15,163 17,495 $ 360 Residential 833 519 635 Home equity 40 8 14 Individuals' loans for household and other personal expenditures 5 5 7 Total $ 25,979 $ 17,931 $ 22,752 $ 360 Impaired loans with related allowance: Commercial and industrial loans $ 812 $ 782 $ 552 $ 1,517 Agriculture production financing and other loans to farmers 357 327 114 327 Real estate loans: Commercial and farmland 2,988 2,269 567 2,379 Residential 1,616 1,572 327 1,580 $ 28 Home equity 350 330 77 332 11 Total $ 6,123 $ 5,280 $ 1,637 $ 6,135 $ 39 Total Impaired Loans $ 32,102 $ 23,211 $ 1,637 $ 28,887 $ 399 December 31, 2016 Unpaid Principal Recorded Related Average Recorded Investment Interest Income Recognized Impaired loans with no related allowance: Commercial and industrial loans $ 4,028 $ 1,696 $ 1,770 $ 37 Agriculture production financing and other loans to farmers 367 338 357 Real estate loans: Commercial and farmland 22,828 17,752 18,944 288 Residential 2,073 1,402 1,665 2 Home equity 60 30 30 Individuals' loans for household and other personal expenditures 9 9 9 Total $ 29,365 $ 21,227 $ 22,775 $ 327 Impaired loans with related allowance: Agriculture production financing and other loans to farmers $ 660 $ 660 $ 36 $ 690 Real estate loans: Commercial and farmland 4,237 2,985 553 2,990 Residential 968 877 233 872 $ 14 Home equity 290 266 66 266 6 Total $ 6,155 $ 4,788 $ 888 $ 4,818 $ 20 Total Impaired Loans $ 35,520 $ 26,015 $ 888 $ 27,593 $ 347 Impaired loans in the above tables do not include loans accounted for under ASC 310-30, or any other loan, unless deemed impaired in accordance with ASC 310-10. 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, (iv) covenant failures and (v) 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 or 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-days or more 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 the probability, at acquisition, that all contractually required payments would not be collected are included in the applicable categories below. December 31, 2018 Commercial Pass Commercial Special Mention Commercial Substandard Commercial Doubtful Commercial Loss Consumer Performing Consumer Total Commercial and industrial loans $ 1,660,879 $ 23,246 $ 42,539 $ 1,726,664 Agriculture production financing and other loans to farmers 78,446 5,966 7,992 92,404 Real estate loans: Construction 492,358 2,185 24,224 $ 25,419 $ 1,543 545,729 Commercial and farmland 2,669,491 76,037 84,288 2,285 1 2,832,102 Residential 170,075 7,373 2,076 782,080 4,817 966,421 Home equity 24,653 535 457 500,996 1,516 528,157 Individuals' loans for household and other personal expenditures 99,741 47 99,788 Lease financing receivables, net of unearned income 1,600 1,600 Other commercial loans 431,249 353 431,602 Loans $ 5,528,751 $ 115,342 $ 161,929 $ 1,410,521 $ 7,924 $ 7,224,467 December 31, 2017 Commercial Pass Commercial Special Mention Commercial Substandard Commercial Doubtful Commercial Loss Consumer Performing Consumer Total Commercial and industrial loans $ 1,418,401 $ 51,336 $ 23,386 $ 370 $ 1,493,493 Agriculture production financing and other loans to farmers 73,800 27,502 20,018 387 $ 50 121,757 Real estate loans: Construction 587,906 828 981 $ 22,374 $ 130 612,219 Commercial and farmland 2,408,329 70,074 79,769 1,536 2,980 3 2,562,691 Residential 185,725 4,376 4,209 114 759,900 8,441 962,765 Home equity 28,554 457 286 482,661 2,063 514,021 Individuals' loans for household and other personal expenditures 86,875 60 86,935 Lease financing receivables, net of unearned income 2,527 2,527 Other commercial loans 394,222 569 394,791 Loans $ 5,099,464 $ 154,573 $ 129,218 $ 2,407 $ 50 $ 1,354,790 $ 10,697 $ 6,751,199 The tables below show a past due aging of the Corporation’s loan portfolio, by loan class, for the years indicated: December 31, 2018 Current 30-59 Days 60-89 Days Loans 90 Days or More Past Due Non-Accrual Total Past Due Total Commercial and industrial loans $ 1,723,337 $ 1,093 $ 182 $ 249 $ 1,803 $ 3,327 $ 1,726,664 Agriculture production financing and other loans to farmers 89,440 2,285 679 2,964 92,404 Real estate loans: Construction 535,520 64 1,478 8,667 10,209 545,729 Commercial and farmland 2,822,515 1,253 178 8,156 9,587 2,832,102 Residential 959,252 1,756 430 17 4,966 7,169 966,421 Home equity 524,198 2,164 207 107 1,481 3,959 528,157 Individuals' loans for household and other personal expenditures 99,499 179 64 4 42 289 99,788 Lease financing receivables, net of unearned income 1,600 1,600 Other commercial loans 431,248 354 354 431,602 Loans $ 7,186,609 $ 8,794 $ 1,061 $ 1,855 $ 26,148 $ 37,858 $ 7,224,467 December 31, 2017 Current 30-59 Days 60-89 Days Loans 90 Days or More Past Due Non-Accrual Total Past Due Total Commercial and industrial loans $ 1,487,221 $ 2,967 $ 30 $ 3,275 $ 6,272 $ 1,493,493 Agriculture production financing and other loans to farmers 120,720 10 1,027 1,037 121,757 Real estate loans: Construction 610,896 1,193 $ 65 65 1,323 612,219 Commercial and farmland 2,542,048 6,923 166 603 12,951 20,643 2,562,691 Residential 948,947 4,010 308 56 9,444 13,818 962,765 Home equity 510,362 1,372 184 175 1,928 3,659 514,021 Individuals' loans for household and other personal expenditures 85,744 298 834 25 34 1,191 86,935 Lease financing receivables, net of unearned income 2,527 2,527 Other commercial loans 394,791 394,791 Loans $ 6,703,256 $ 16,773 $ 1,522 $ 924 $ 28,724 $ 47,943 $ 6,751,199 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 works 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 restructures in the Corporation's loan portfolio that occurred during the periods ended December 31, 2018 and 2017 : December 31, 2018 Pre-Modification Post-Modification Number Real estate loans: Commercial and farmland $ 85 $ 85 1 Residential 490 487 11 Home equity 81 81 3 Individuals' loans for household and other personal expenditures 65 66 3 Total $ 721 $ 719 18 December 31, 2017 Pre-Modification Post-Modification Number Commercial and industrial loans $ 599 $ 376 3 Agriculture production financing and other loans to farmers 387 387 3 Real estate loans: Commercial and farmland 1,022 1,156 8 Residential 788 862 15 Home equity 195 107 4 Individuals' loans for household and other personal expenditures 13 14 1 Total $ 3,004 $ 2,902 34 The following tables summarize the recorded investment of troubled debt restructures as of December 31, 2018 and 2017 , by modification type, that occurred during the years indicated: December 31, 2018 Term Rate Combination Total Real estate loans: Commercial and farmland $ 85 $ 85 Residential $ 209 $ 239 448 Home equity 106 74 180 Individuals' loans for household and other personal expenditures 58 6 64 Total $ 249 $ 289 $ 239 $ 777 December 31, 2017 Term Rate Combination Total Commercial and industrial loans $ 203 $ 166 $ 369 Agriculture production financing and other loans to farmers 387 387 Real estate loans: Commercial and farmland 705 $ 59 232 996 Residential 761 85 846 Home equity 105 105 Individuals' loans for household and other personal expenditures 14 14 Total $ 1,295 $ 939 $ 483 $ 2,717 Loans secured by 1- 4 family residential real estate made up 79 percent of the post-modification balances of the troubled debt restructured loans that occurred during the twelve months ending December 31, 2018 . The following tables summarize troubled debt restructures that occurred during the twelve months ended December 31, 2018 and 2017 , 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-days or more past due. Twelve Months Ended December 31, 2018 Number of Loans Recorded Balance Real estate loans: Residential 2 $ 75 Total 2 $ 75 Twelve Months Ended December 31, 2017 Number of Loans Recorded Balance Real estate loans: Commercial and farmland 1 $ 14 Residential 4 323 Total 5 $ 337 For potential consumer loan restructures, impairment evaluation occurs prior to modification. Any subsequent impairment is addressed through the charge-off process or through a specific reserve. Consumer troubled debt restructures are generally included in the general historical allowance for loan loss at the post modification balance. Consumer non-accrual and delinquent troubled debt restructures are also considered in the calculation of the non-accrual and delinquency trend environmental allowance allocation. Consumer loans secured by residential real estate properties for which formal foreclosure proceedings are in process totaled $800,000 and $2,302,000 at December 31, 2018 and 2017, respectively. 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 restructures are included in the calculation of the delinquency trend environmental allowance allocation. With the exception of the acquired loans excluded from the allowance for loan losses, all commercial non-impaired loans, including non-accrual and 90-days or more delinquents, are included in the ASC 450 loss estimate.

Accounting for Certain Loans Ac

Accounting for Certain Loans Acquired in a Purchase	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Accounting for Certain Loans Acquired in a Purchase	ACCOUNTING FOR CERTAIN LOANS ACQUIRED IN A PURCHASE Purchase Credit Impaired Loans are included in NOTE 5. LOANS AND ALLOWANCE of these Notes to Consolidated Financial Statements. As described in NOTE 5, purchased loans 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 difference. 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. The carrying amount of purchased credit impaired loans as of December 31, 2018 and December 31, 2017 was $17.3 million and $25.3 million , respectively; with no required allowance for loan losses. As customer cash flow expectations improve, nonaccretable yield can be reclassified to accretable yield. The accretable amount, or income expected to be collected, and reclassifications from nonaccretable, are identified in the table below. Twelve Months Ended December 31, 2018 Twelve Months Ended December 31, 2017 Twelve Months Ended December 31, 2016 Beginning balance $ 2,890 $ 3,950 $ 5,612 Additions 1,608 Accretion (4,118 ) (6,749 ) (6,577 ) Reclassification from nonaccretable 3,387 4,748 5,172 Disposals (16 ) (667 ) (257 ) Ending balance $ 2,143 $ 2,890 $ 3,950 The following table presents loans acquired during the period ending December 31, 2017, for which it was probable at acquisition that all contractually required payments would not be collected. There were no loans acquired during the period ending December 31, 2018. 2017 IAB Arlington Bank Total Contractually required payments receivable at acquisition date $ 14,131 $ 6,183 $ 20,314 Nonaccretable difference 8,352 2,891 11,243 Expected cash flows at acquisition date 5,779 3,292 9,071 Accretable difference 941 667 1,608 Basis in loans at acquisition date $ 4,838 $ 2,625 $ 7,463

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 : 2018 2017 Cost at December 31: Land $ 21,762 $ 22,042 Buildings and Leasehold Improvements 125,366 124,441 Equipment 86,498 82,344 Total Cost 233,626 228,827 Accumulated Depreciation and Amortization (140,206 ) (132,975 ) Net $ 93,420 $ 95,852 The IAB acquisition on July 14, 2017 and the Arlington Bank acquisition on May 19, 2017 resulted in additions to premises and equipment of $10,107,000 and $1,986,000 , respectively. Details regarding the acquisitions are discussed in NOTE 2. ACQUISITIONS of these Notes to Consolidated Financial Statements. The Corporation is committed under various non-cancelable lease contracts for certain subsidiary office facilities and equipment. Total lease expense for 2018 , 2017 and 2016 was $4,369,000 , $4,072,000 and $4,586,000 , respectively. The future minimum rental commitments required under the operating leases, which expire at various dates through the year 2035, are as follows for the years ending December 31: Future Minimum Rental Commitments 2019 $ 3,721 2020 3,584 2021 3,283 2022 3,150 2023 2,622 After 2023 12,495 Total Future Minimum Obligations $ 28,855

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	GOODWILL Goodwill is recorded on the acquisition date of an entity. During the measurement period, the Corporation may record subsequent adjustments to goodwill for provisional amounts recorded at the acquisition date. The IAB acquisition on July, 14, 2017 resulted in $153,636,000 of goodwill. The Arlington Bank acquisition on May 19, 2017 resulted in $47,719,000 of goodwill, which includes a reduction of $469,000 . This reduction was recorded in the third quarter of 2017 as a measurement period adjustment. Details regarding the IAB and Arlington Bank acquisitions are discussed in NOTE 2. ACQUISITIONS of these Notes to Consolidated Financial Statements. There have been no changes in goodwill since December 31, 2017 , resulting in a goodwill balance of $445,355,000 as of December 31, 2018 . No impairment loss was recorded in 2018 or 2017. The Corporation tested goodwill for impairment during 2018 and 2017. 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. 2017 Balance, January 1 $ 244,000 Goodwill acquired 201,824 Measurement period adjustment $ (469 ) Balance, December 31 $ 445,355

Other Intangibles

Other Intangibles	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Other Intangibles	OTHER INTANGIBLES Core deposit intangibles and other intangibles are recorded on the acquisition date of an entity. During the measurement period, the Corporation may record subsequent adjustments to these intangibles for provisional amounts recorded at the acquisition date. The IAB acquisition on July 14, 2017 resulted in a core deposit intangible of $13,638,000 and other intangibles, consisting of non-compete intangibles, of $3,765,000 . The Arlington Bank acquisition on May 19, 2017 resulted in a core deposit intangible of $4,526,000 . Details regarding the IAB and Arlington Bank acquisitions are discussed in NOTE 2. ACQUISITIONS of these in the Notes to Consolidated Financial Statements. The carrying basis and accumulated amortization of recognized core deposit and other intangibles are noted below. 2018 2017 Gross carrying amount $ 85,869 $ 63,940 Core deposit intangible acquired 18,164 Other intangibles acquired 3,765 Accumulated amortization (61,440 ) (54,721 ) Core Deposit and Other Intangibles $ 24,429 $ 31,148 Amortization expense for the years ended December 31, 2018 , 2017 and 2016 , was $6,719,000 , $5,647,000 and $3,910,000 , respectively. Estimated future amortization expense is summarized as follows: Amortization Expense 2019 $ 5,169 2020 3,632 2021 3,427 2022 3,325 2023 3,175 After 2023 5,701 $ 24,429

Deposits

Deposits	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Deposits	DEPOSITS The composition of the deposit portfolio is included in the table below for the years indicated: December 31, 2018 December 31, 2017 Demand deposits $ 3,985,178 $ 3,746,654 Savings deposits 2,282,701 1,994,366 Certificates and other time deposits of $100,000 or more 593,592 468,895 Other certificates and time deposits 646,682 581,894 Brokered deposits 246,440 380,721 Total deposits $ 7,754,593 $ 7,172,530 At December 31, 2018 and 2017 , deposits exceeding the FDIC's Standard Maximum Deposit Insurance Amount of $250,000 were $3.8 billion and $3.2 billion , respectively. At December 31, 2018 , the contractual maturities of time deposits are summarized as follows: Certificates and Other Time Deposits 2019 $ 1,007,653 2020 361,663 2021 70,327 2022 27,535 2023 17,977 After 2023 1,559 $ 1,486,714

Transfers Accounted for as Secu

Transfers Accounted for as Secured Borrowings	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Transfers Accounted for as Secured Borrowings	TRANSFERS ACCOUNTED FOR AS SECURED BORROWINGS The collateral pledged for all repurchase agreements that are accounted for as secured borrowings as of December 31, 2018 and 2017 were: December 31, 2018 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater Than 90 Days Total U.S. Government-sponsored mortgage-backed securities $ 104,883 1,014 7,615 $ 113,512 December 31, 2017 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater Than 90 Days Total U.S. Government-sponsored mortgage-backed securities $ 126,187 1,340 1,500 7,596 $ 136,623

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Borrowings	BORROWINGS The following table summarizes the Corporation's borrowings as of December 31, 2018 and 2017: December 31, 2018 December 31, 2017 Federal funds purchased $ 104,000 $ 144,038 Securities sold under repurchase agreements 113,512 136,623 Federal Home Loan Bank advances 314,986 414,377 Subordinated debentures and term loans 138,463 139,349 Total Borrowings $ 670,961 $ 834,387 Securities sold under repurchase agreements consist of obligations of the Bank to other parties and are secured by U.S. Government-Sponsored Enterprise obligations. The maximum amount of outstanding agreements at any month-end during 2018 and 2017 totaled $143,016,000 and $145,883,000 , respectively, and the average of such agreements totaled $124,762,000 and $134,401,000 during 2018 and 2017 , respectively. Contractual maturities of borrowings as of December 31, 2018 , are as follows: Maturities in Years Ending December 31: Federal Funds Purchased Securities Sold Federal Home Subordinated 2019 $ 104,000 $ 113,512 $ 113,713 2020 41,273 2021 55,000 2022 45,000 2023 35,000 After 2023 25,000 $ 142,322 ASC 805 fair value adjustments at acquisition (3,859 ) $ 104,000 $ 113,512 $ 314,986 $ 138,463 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 145 percent of these advances depending on the type of collateral pledged. At December 31, 2018, the outstanding FHLB advances had interest rates from 0.96 to 5.09 percent and are subject to restrictions or penalties in the event of prepayment. The total available remaining borrowing capacity from the FHLB at December 31, 2018 , was $629,237,000 . As of December 31, 2018 , the Corporation had $45,000,000 of putable advances with the FHLB. Subordinated Debentures and Term Loans. As of December 31, 2018 and 2017 , subordinated debentures and term loans totaled $138,463,000 and $ 139,349,000 , respectively. • First Merchants Capital Trust II. The subordinated debenture was entered into on July 2, 2007 for $56,702,000 . On August 10, 2015, the Corporation completed the cancellation of $5 million of subordinated debentures at a gain of $1,250,000 . As of December 31, 2018 , $51,702,000 of subordinated debentures remain outstanding with a maturity date of 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, 2018 and 2017 was 4.35 percent and 3.15 percent , respectively. The Corporation holds all of the outstanding common securities of First Merchants Capital Trust II. • Ameriana Capital Trust I. On December 31, 2015 the Corporation acquired Ameriana Capital Trust I in conjunction with its acquisition of Ameriana Bancorp, Inc. The subordinated debentures of Ameriana Capital Trust I were entered into in March 2006 for $10,310,000 and have a maturity of March 2036. Ameriana could not redeem the debenture prior to March 2011, and redemption is subject to the prior approval of the Board of Governors of the Federal Reserve System, as required by law or regulation. The interest rate is equal to the three-month LIBOR plus 1.50 percent , reset quarterly. Interest is payable in March, June, September and December of each year. The interest rate at December 31, 2018 and 2017 was 4.29 percent and 3.09 percent , respectively. The Corporation holds all of the outstanding common securities of Ameriana Capital Trust I. • Grabill Capital Trust I. On July 14, 2017 the Corporation acquired Grabill Capital Trust I in conjunction with its acquisition of Independent Alliance Banks, Inc. The subordinated debentures of Grabill Capital Trust I were entered into in June 2004 for $10,310,000 and have a maturity of July 23, 2034. IAB could not redeem the debenture prior to July 2009, and redemption is subject to the prior approval of the Board of Governors of the Federal Reserve System, as required by law or regulation. The interest rate is equal to the three-month LIBOR plus 2.60 percent , reset quarterly. Interest is payable in January, April, July and October of each year. The interest rate at December 31, 2018 and 2017 was 5.08 percent and 3.96 percent , respectively. The Corporation holds all of the outstanding common securities of Grabill Capital Trust I. • 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. Once the rates convert to floating on October 30, 2023, the Senior Debt will have an annual floating rate equal to the three-month LIBOR plus 2.345 percent and the Subordinated Debt will have an annual floating rate equal to the three-month LIBOR plus 4.095 percent . The Corporation has an option to redeem the Subordinated Debt in whole or in part at a redemption price equal to 100 percent of the principal amount of the redeemed Subordinated Notes, plus accrued and unpaid interest to the date of the redemption. The option of redemption is subject to the approval of the Federal Reserve Board. The Corporation has an option to redeem the Senior Debt in whole or in part at a redemption price equal to 100 percent of the principal amount of the redeemed Senior Notes, plus accrued and unpaid interest to the date of the redemption; provided, however, that no Subordinated Notes (as defined in the Issuing and Paying Agency Agreement) may remain outstanding subsequent to any early redemption of Senior Notes. The Subordinated Debt and the Senior Debt options to redeem begin with the interest payment date on October 30, 2023, or on any scheduled interest payment date thereafter. The Senior Debt agreement contains certain customary representations and warranties and financial and negative covenants. As of December 31, 2018 and 2017 the Corporation was in compliance with these covenants.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	12 Months Ended
	Dec. 31, 2018
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. 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, 2018 , the Corporation had four interest rate swaps with a notional amount of $46.0 million and one interest rate cap with a notional amount of $13.0 million . As of December 31, 2017 , 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 . A $10.0 million interest rate swap used to hedge the variable cash outflows associated with a Federal Home Loan Bank advance matured in the third quarter of 2018. 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 2018 , $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 $20.0 million of interest rate swaps were used to hedge the variable cash outflows (LIBOR-based) associated with two 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, 2018 and 2017 , 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 $208,000 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, 2018 , the notional amount of customer-facing swaps was approximately $477,776,000 . This amount is offset with third party counterparties, as described above. 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, 2018 and December 31, 2017 . Asset Derivatives Liability Derivatives December 31, 2018 December 31, 2017 December 31, 2018 December 31, 2017 Balance Sheet Location Fair Balance Sheet Location Fair Balance Sheet Location Fair Balance Sheet Location Fair Derivatives designated as hedging instruments: Interest rate contracts Other Assets $ 135 Other Assets $ 18 Other Liabilities $ 688 Other Liabilities $ 1,383 Derivatives not designated as hedging instruments: Interest rate contracts Other Assets $ 11,948 Other Assets $ 7,305 Other Liabilities $ 11,948 Other Liabilities $ 7,305 The amount of gain (loss) recognized in other comprehensive income is included in the table below for the periods indicated. Derivatives in Cash Flow Hedging Relationships Amount of Gain (Loss) Recognized in Other Comprehensive Income on Derivative 2018 2017 Interest rate products $ 247 $ 13 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, 2018 , 2017 and 2016 . Derivatives Not Location of Gain Amount of Gain (Loss) Recognized in Income on Derivative 2018 2017 2016 Interest rate contracts Other income $ 211 Derivatives Designated as Hedging Location of Loss Reclassified from Accumulated Other Comprehensive Income (Effective Portion) Amount of Loss Reclassified from Other Comprehensive Income into Income (Effective Portion) 2018 2017 2016 Interest rate contracts Interest expense $ (470 ) $ (985 ) $ (1,250 ) 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, 2018 , the termination value of derivatives in a net liability position related to these agreements was $3,302,000 . As of December 31, 2018 , the Corporation has minimum collateral posting thresholds with certain of its derivative counterparties and has posted collateral of $5,195,000 . If the Corporation had breached any of these provisions at December 31, 2018 , it could have been required to settle its obligations under the agreements at their termination value.

Fair Values of Financial Instru

Fair Values of Financial Instruments	12 Months Ended
	Dec. 31, 2018
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 non-recurring 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 sheets, as well as the general classification of such instruments pursuant to the valuation hierarchy. Investment Securities Where quoted prices are available in an active market, securities are classified within Level 1 of the valuation hierarchy. The Corporation currently has no securities classified within Level 1 of the hierarchy. Where significant observable inputs, other than Level 1 quoted prices, are available, securities are classified within Level 2 of the valuation hierarchy. Level 2 securities include government-sponsored agency and mortgage backed, and state and municipal 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, government-sponsored mortgage backed and corporate obligations securities. Level 3 fair value for 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. Interest Rate Derivative Agreements See information regarding the Corporation’s interest rate derivative products in NOTE 13. DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES of these Notes to Consolidated Financial Statements. 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, 2018 and 2017 . Fair Value Measurements Using: Quoted Prices in Active Significant Other Observable Inputs Significant December 31, 2018 Fair Value (Level 1) (Level 2) (Level 3) Available for sale securities: U.S. Government-sponsored agency securities $ 13,582 $ 13,582 State and municipal 606,135 602,842 $ 3,293 U.S. Government-sponsored mortgage-backed securities 522,447 522,443 4 Corporate obligations 31 31 Interest rate swap asset 11,948 11,948 Interest rate cap 135 135 Interest rate swap liability 12,636 12,636 Fair Value Measurements Using: Quoted Prices in Active Significant Other Observable Inputs Significant December 31, 2017 Fair Value (Level 1) (Level 2) (Level 3) Available for sale securities: U.S. Government-sponsored agency securities State and municipal $ 526,693 $ 522,750 $ 3,943 U.S. Government-sponsored mortgage-backed securities 470,866 470,866 Corporate obligations 31 31 Equity securities 2,357 2,353 4 Interest rate swap asset 7,305 7,305 Interest rate cap 18 18 Interest rate swap liability 8,688 8,688 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, 2018 and 2017 . Available for Sale Securities For The Year Ended December 31, 2018 December 31, 2017 Beginning Balance $ 3,978 $ 5,169 Included in other comprehensive income (49 ) 26 Principal payments (601 ) (1,217 ) Ending balance $ 3,328 $ 3,978 There were no gains or losses included in earnings that were attributable to the changes in unrealized gains or losses related to assets or liabilities held at December 31, 2018 or 2017 . TRANSFERS BETWEEN LEVELS There were no transfers in or out of Level 3 during 2018 or 2017. 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, 2018 and 2017 . Fair Value Measurements Using Quoted Prices in Active Significant Other Observable Inputs Significant December 31, 2018 Fair Value (Level 1) (Level 2) (Level 3) Impaired Loans (collateral dependent) $ 11,866 $ 11,866 Other real estate owned $ 657 $ 657 Fair Value Measurements Using Quoted Prices in Active Significant Other Observable Inputs Significant December 31, 2017 Fair Value (Level 1) (Level 2) (Level 3) Impaired Loans (collateral dependent) $ 9,576 $ 9,576 Other real estate owned $ 859 $ 859 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 2018 , 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 discounted 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, 2018 and 2017 . December 31, 2018 Fair Value Valuation Technique Unobservable Inputs Range (Weighted-Average) State and municipal securities $ 3,293 Discounted cash flow Maturity Call Date 1 month to 20 years Corporate obligations and U.S. Government-sponsored mortgage backed securities $ 35 Discounted cash flow Risk free rate 3 month LIBOR Impaired loans (collateral dependent) $ 11,866 Collateral based measurements Discount to reflect current market conditions and ultimate collectability 0% - 10% (6%) Other real estate owned $ 657 Appraisals Discount to reflect current market conditions 0% - 10% (4%) December 31, 2017 Fair Value Valuation Technique Unobservable Inputs Range (Weighted-Average) State and municipal securities $ 3,943 Discounted cash flow Maturity Call Date 1 month to 20 years Corporate obligations and U.S. Government-sponsored mortgage backed securities $ 35 Discounted cash flow Risk free rate 3 month LIBOR Impaired loans (collateral dependent) $ 9,576 Collateral based measurements Discount to reflect current market conditions and ultimate collectability 0% - 10% (1%) Other real estate owned $ 859 Appraisals Discount to reflect current market conditions 0% - 10% (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, U.S. Government-sponsored Mortgage Backed Securities The significant unobservable inputs used in the fair value measurement of the Corporation's state and municipal securities, corporate obligations and U.S. Government-sponsored mortgage backed 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, 2018 and 2017 . 2018 Carrying Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Assets at December 31: Cash and cash equivalents $ 139,247 $ 139,247 Interest-bearing time deposits 36,963 36,963 Investment securities available for sale 1,142,195 $ 1,138,867 $ 3,328 Investment securities held to maturity 490,387 481,377 7,840 Loans held for sale 4,778 4,778 Loans 7,143,915 7,004,193 Federal Home Loan Bank stock 24,588 24,588 Interest rate swap asset 12,083 12,083 Interest receivable 40,881 40,881 Liabilities at December 31: Deposits $ 7,754,593 $ 6,267,879 $ 1,464,129 Borrowings: Federal funds purchased 104,000 104,000 Securities sold under repurchase agreements 113,512 113,437 Federal Home Loan Bank advances 314,986 318,728 Subordinated debentures and term loans 138,463 127,298 Interest rate swap liability 12,636 12,636 Interest payable 5,607 5,607 2017 Carrying Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Assets at December 31: Cash and cash equivalents $ 154,905 $ 154,905 Interest-bearing time deposits 35,027 35,027 Investment securities available for sale 999,947 $ 995,969 $ 3,978 Investment securities held to maturity 560,655 556,305 11,903 Loans held for sale 7,216 7,216 Loans 6,676,167 6,534,877 Federal Home Loan Bank stock 23,825 23,825 Interest rate swap asset 7,323 7,323 Interest receivable 37,130 37,130 Liabilities at December 31: Deposits $ 7,172,530 $ 5,741,019 $ 1,406,526 Borrowings: Federal funds purchased 144,038 144,038 Securities sold under repurchase agreements 136,623 136,562 Federal Home Loan Bank advances 414,377 361,085 Subordinated debentures and term loans 139,349 120,085 Interest rate swap liability 8,688 8,688 Interest payable 4,390 4,390 The methods utilized to estimate the fair value of financial instruments at December 31, 2017 did not necessarily represent an exit price. In accordance with the Corporation's adoption of ASU 2016-01 as of January 1, 2018, the methods utilized to measure the fair value of financial instruments at December 31, 2018 represent an approximation of exit price; however, an actual exit price may differ.

Commitments and Contingent Liab

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2018
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: 2018 2017 Amounts of commitments: Loan commitments to extend credit $ 2,684,806 $ 2,482,641 Standby letters of credit $ 32,862 $ 43,526 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.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 : Accumulated Other Comprehensive Income (Loss) Unrealized Gains (Losses) on Securities Available for Sale Unrealized Gains (Losses) on Cash Flow Hedges Unrealized Gains (Losses) on Defined Benefit Plans Total Balance at December 31, 2017 $ 8,970 $ (1,125 ) $ (10,753 ) $ (2,908 ) Other comprehensive income before reclassifications (13,872 ) 437 (1,435 ) (14,870 ) Amounts reclassified from accumulated other comprehensive income (3,373 ) 371 (16 ) (3,018 ) Period change (17,245 ) 808 (1,451 ) (17,888 ) Reclassification adjustment under ASU 2018-02 1,932 (242 ) (2,316 ) (626 ) Balance at December 31, 2018 $ (6,343 ) $ (559 ) $ (14,520 ) $ (21,422 ) Balance at December 31, 2016 $ 1,035 $ (1,774 ) $ (12,842 ) $ (13,581 ) Other comprehensive income before reclassifications 9,645 9 2,686 12,340 Amounts reclassified from accumulated other comprehensive income (1,710 ) 640 (597 ) (1,667 ) Period change 7,935 649 2,089 10,673 Balance at December 31, 2017 $ 8,970 $ (1,125 ) $ (10,753 ) $ (2,908 ) 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 years ended December 31, 2018 , 2017 and 2016 : Amount Reclassified from Accumulated Other Comprehensive Income (Loss) For the Year Ended December 31, Details about Accumulated Other Comprehensive Income (Loss) Components 2018 2017 2016 Affected Line Item in the Statements of Income Unrealized gains (losses) on available for sale securities (1) Realized securities gains reclassified into income $ 4,269 $ 2,631 $ 3,389 Other income - net realized gains on sales of available for sale securities Related income tax expense (896 ) (921 ) (1,186 ) Income tax expense $ 3,373 $ 1,710 $ 2,203 Unrealized gains (losses) on cash flow hedges (2) Interest rate contracts $ (470 ) $ (985 ) $ (1,250 ) Interest expense - subordinated debentures and term loans Related income tax benefit 99 345 437 Income tax expense $ (371 ) $ (640 ) $ (813 ) Unrealized gains (losses) on defined benefit plans Amortization of net loss and prior service costs $ 20 $ 806 $ 1,588 Other expenses - salaries and employee benefits Related income tax benefit (expense) (4 ) (209 ) (556 ) Income tax expense $ 16 $ 597 $ 1,032 Total reclassifications for the period, net of tax $ 3,018 $ 1,667 2,422 (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 4. 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 and Dividend

Regulatory Capital and Dividends	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Regulatory Capital and Dividends	REGULATORY CAPITAL AND DIVIDENDS Regulatory Capital Capital adequacy is an important indicator of financial stability and performance. 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 four ratios that are calculated according to the regulations: total risk-based capital, tier 1 risk-based capital, common equity 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. Quantitative measures established by regulation to ensure capital adequacy require the Bank to maintain minimum amounts and ratios of total and tier 1 capital to risk-weighted assets, and of tier 1 capital to average assets, or leverage ratio, all of which are calculated as defined in the regulations. Banks with lower capital levels are deemed to be undercapitalized, significantly undercapitalized or critically undercapitalized, depending on their actual levels. The appropriate federal regulatory agency may also downgrade a bank to the next lower capital category upon a determination that the bank is in an unsafe or unsound practice. Banks are required to monitor closely their capital levels and to notify their appropriate regulatory agency of any basis for a change in capital category. Basel III was effective for the Corporation on January 1, 2015. Basel III requires the Corporation and the Bank to maintain a minimum ratio of CET1 capital to risk weighted assets, as defined in the regulation. Under the new Basel III rules, in order to avoid limitations on capital distributions, including dividends, the Corporation must hold a capital conservation buffer above the adequately capitalized CET1 capital to risk-weighted assets ratio. The capital conservation buffer was phased in from zero percent in 2015 to the fully-implemented 2.50 percent in 2019. During 2018, the Corporation was required to hold a capital conservation buffer of 1.875 percent, which amount increases by 0.625 percent for 2019, the final year of the phase-in. Under Basel III, the Corporation and Bank elected to opt-out of including AOCI in regulatory capital. As of December 31, 2018 , the Bank met all capital adequacy requirements to be considered well capitalized. There is no threshold for well capitalized status for bank holding companies. The Corporation's and Bank's actual and required capital ratios as of December 31, 2018 and December 31, 2017 were as follows: Prompt Corrective Action Thresholds Actual Adequately Capitalized Well Capitalized December 31, 2018 Amount Ratio Amount Ratio Amount Ratio Total risk-based capital to risk-weighted assets First Merchants Corporation $ 1,177,725 14.61 % $ 644,871 8.00 % N/A N/A First Merchants Bank 1,092,602 13.46 649,531 8.00 $ 811,914 10.00 % Tier 1 capital to risk-weighted assets First Merchants Corporation $ 1,032,173 12.80 % $ 483,653 6.00 % N/A N/A First Merchants Bank 1,012,050 12.47 487,148 6.00 $ 649,531 8.00 % Common equity tier 1 capital to risk-weighted assets First Merchants Corporation $ 966,032 11.98 % $ 362,740 4.50 % N/A N/A First Merchants Bank 1,012,050 12.47 365,361 4.50 $ 527,744 6.50 % Tier 1 capital to average assets First Merchants Corporation $ 1,032,173 10.91 % $ 378,379 4.00 % N/A N/A First Merchants Bank 1,012,050 10.70 378,397 4.00 $ 472,996 5.00 % Prompt Corrective Action Thresholds Actual Adequately Capitalized Well Capitalized December 31, 2017 Amount Ratio Amount Ratio Amount Ratio Total risk-based capital to risk-weighted assets First Merchants Corporation $ 1,048,757 13.69 % $ 612,848 8.00 % N/A N/A First Merchants Bank 1,016,355 13.17 617,477 8.00 $ 771,847 10.00 % Tier 1 capital to risk-weighted assets First Merchants Corporation $ 908,725 11.86 % $ 459,636 6.00 % N/A N/A First Merchants Bank 941,323 12.20 463,108 6.00 $ 617,477 8.00 % Common equity tier 1 capital to risk-weighted assets First Merchants Corporation $ 842,806 11.00 % $ 344,727 4.50 % N/A N/A First Merchants Bank 941,323 12.20 347,331 4.50 $ 501,700 6.50 % Tier 1 capital to average assets First Merchants Corporation $ 908,725 10.43 % $ 348,407 4.00 % N/A N/A First Merchants Bank 941,323 10.83 347,794 4.00 $ 434,742 5.00 % Management believes that all of the above capital ratios are meaningful measurements for evaluating the safety and soundness of the Corporation. Traditionally, the banking regulators have assessed bank and bank holding company capital adequacy based on both the amount and the composition of capital, the calculation of which is prescribed in federal banking regulations. The Federal Reserve focuses its assessment of capital adequacy on a component of Tier 1 capital known as CET1. Because the Federal Reserve has long indicated that voting common shareholders' equity (essentially Tier 1 risk-based capital less preferred stock and non-controlling interest in subsidiaries) generally should be the dominant element in Tier 1 risk-based capital, this focus on CET1 is consistent with existing capital adequacy categories. Tier I regulatory capital consists primarily of total stockholders’ equity and subordinated debentures issued to business trusts categorized as qualifying borrowings, less non-qualifying intangible assets and unrealized net securities gains or losses. Because these measures are not defined in GAAP, they are considered non-GAAP financial measures. Non-GAAP financial measures have inherent limitations, are not required to be uniformly applied, and are not audited. Although these non-GAAP financial measures are frequently used by investors to evaluate a company, they have limitations as analytical tools, and should not be considered in isolation, or as a substitute for analyses of results as reported under GAAP. For a reconciliation of GAAP measures to regulatory measures (non-GAAP), see additional details within the “Capital” 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. Dividends The Corporation's principal source of funds for dividend payments to shareholders is dividends received from the Bank. Banking regulations limit the maximum amount of dividends that a bank may pay without requesting prior approval of regulatory agencies. Under these regulations, the amount of dividends that may be paid in any calendar year is limited to the bank’s retained net income (as defined) for the current year plus those for the previous two years, subject to the capital requirements described above. As of December 31, 2018 , the amount available without prior regulatory approval for 2019 dividends from the Corporation’s subsidiaries (both banking and non-banking) was $192,712,000 . Additionally, 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. Stock Repurchase Program On February 9, 2016, the Board of Directors of the Corporation approved a stock repurchase program of up to $15 million of the outstanding shares of the Corporation's common stock. The shares may be purchased from time to time in open market transactions at prevailing market prices in accordance with federal securities laws. The Corporation is not obligated to purchase any shares under the program, and the program may be discontinued at any time. The actual timing, number and share price of shares purchased under the repurchase program will be determined by the Corporation at its discretion and will depend upon such factors as the market price of the stock, general market and economic conditions and applicable legal requirements.

Loan Servicing

Loan Servicing	12 Months Ended
	Dec. 31, 2018
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, Fannie Mae, Federal Home Loan Bank of Cincinnati and Federal Home Loan Bank of Indianapolis, and the unpaid balances totaled $533,386,000 , $549,618,000 and $369,592,000 at December 31, 2018 , 2017 and 2016 , respectively. The amount of capitalized servicing assets is considered immaterial.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	SHARE-BASED COMPENSATION Stock options and 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 based on time 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. The 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. The 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") were credited to non-employee directors who elected to defer payment of compensation under the Corporation's 2008 Equity Compensation Plan for Non-employee Directors, which expired in 2018. DSUs credited are equal to the restricted shares that the non-employee director would have received under the plan. As of December 31, 2018 , the Corporation did not have any outstanding DSUs. The Corporation’s 2009 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, 2018 , 2017 , and 2016 was $3,592,000 , $2,827,000 , and $2,600,000 , respectively, and has been recognized as a component of salaries and benefits expense in the accompanying CONSOLIDATED STATEMENTS OF INCOME. 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 2.2 percent for the year ended December 31, 2018 , based on historical experience. The following table summarizes the components of the Corporation's share-based compensation awards recorded as an expense and the income tax benefit of such awards. The income tax benefit decrease for the year ended December 31, 2018 was due to the reduction of the corporate federal income tax rate from 35 percent to 21 percent as a result of the Tax Cuts and Jobs Act, which was effective January 1, 2018. The income tax benefit increase for the year ended December 31, 2017 was due to the implementation of ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . This ASU requires all income tax effects of awards to be recognized as income tax expense or benefit in the income statement when the awards vest or are settled. Implementation of the ASU was effective January 1, 2017 and resulted in approximately $644,000 and $935,000 of income tax benefit for the years ended December 31, 2018 and 2017, respectively. Years Ended December 31, 2018 2017 2016 Stock and ESPP Options Pre-tax compensation expense $ 109 $ 121 $ 76 Income tax expense (benefit) (97 ) (322 ) 18 Stock and ESPP option expense, net of income taxes $ 12 $ (201 ) $ 94 Restricted Stock Awards Pre-tax compensation expense $ 3,483 $ 2,706 $ 2,524 Income tax benefit (1,179 ) (1,561 ) (883 ) Restricted stock awards expense, net of income taxes $ 2,304 $ 1,145 $ 1,641 Total Share-Based Compensation: Pre-tax compensation expense $ 3,592 $ 2,827 $ 2,600 Income tax benefit (1,276 ) (1,883 ) (865 ) Total share-based compensation expense, net of income taxes $ 2,316 $ 944 $ 1,735 As of December 31, 2018 , unrecognized compensation expense related to RSAs was $7,031,000 and is expected to be recognized over weighted-average period of 1.42 years. The Corporation did no t have any unrecognized compensation expense related to stock options as of December 31, 2018 . Stock option activity under the Corporation's stock option plans, as of December 31, 2018 , and changes during the year ended December 31, 2018 , were as follows: Number of Weighted-Average Price Weighted Average Aggregate Outstanding at January 1, 2018 152,652 $ 16.71 Exercised (76,152 ) $ 20.99 Canceled (200 ) $ 28.25 Outstanding December 31, 2018 76,300 $ 12.40 2.86 $ 1,668,871 Vested and Expected to Vest at December 31, 2018 76,300 $ 12.40 2.86 $ 1,668,871 Exercisable at December 31, 2018 76,300 $ 12.40 2.86 $ 1,668,871 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 2018 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, 2018 . 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, 2018 and 2017 was $1,685,000 and $1,728,000 , respectively. Cash receipts of stock options exercised during 2018 and 2017 were $1,598,000 and $2,398,000 , respectively. The following table summarizes information on unvested RSAs outstanding as of December 31, 2018 : Number of Weighted-Average Unvested RSAs at January 1, 2018 366,993 $ 29.79 Granted 105,100 $ 48.11 Forfeited (15,198 ) $ 42.00 Vested (112,533 ) $ 23.84 Unvested RSAs at December 31, 2018 344,362 $ 36.80 The grant date fair value of ESPP options was estimated at the beginning of the October 1, 2018, quarterly offering period of approximately $21,000 . The ESPP options vested during the three months ending December 31, 2018 , leaving no unrecognized compensation expense related to unvested ESPP options at December 31, 2018 .

Pension and Other Post Retireme

Pension and Other Post Retirement Benefit Plans	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Pension and Other Post Retirement Benefit Plans	PENSION AND OTHER POST RETIREMENT BENEFIT PLANS The Corporation’s defined-benefit pension plans, including non-qualified plans for certain employees, former employees and former non-employee directors, cover approximately 13 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 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, 2018 and 2017 . 2018 2017 Change in Benefit Obligation: Benefit obligation at beginning of year $ 82,157 $ 84,090 Service cost 8 10 Interest cost 2,816 3,353 Actuarial (gain) loss (6,129 ) 3,686 Benefits paid (5,659 ) (5,179 ) Plan settlements (3,803 ) Benefit obligation at end of year $ 73,193 $ 82,157 Change in Plan Assets: Fair value of plan assets at beginning of year $ 85,213 $ 83,557 Actual return on plan assets (3,427 ) 9,968 Employer contributions 609 670 Benefits paid (5,659 ) (5,179 ) Plan settlements (3,803 ) End of year 76,736 85,213 Funded status at end of year $ 3,543 $ 3,056 Assets and Liabilities Recognized in the Balance Sheets: Deferred tax asset $ 3,855 $ 3,474 Assets $ 7,024 $ 7,660 Liabilities $ 3,481 $ 4,604 Amounts Recognized in Accumulated Other Comprehensive Income Not Yet Recognized as Components of Net Periodic Cost, net of tax, consist of: Accumulated loss $ (14,111 ) $ (10,360 ) Prior service cost (409 ) (393 ) $ (14,520 ) $ (10,753 ) The actuarial (gain) loss recognized in 2018 and 2017 was primarily a result of discount rate assumption fluctuations. In 2017, the Corporation offered certain terminated vested pension plan participants the opportunity to elect a lump sum payment during a specific distribution window. The lump sums paid, or plan settlements, released $4.6 million of benefit obligation, while lump sum payments were $3.8 million . The total amount of lump sum payment elections and lump sums paid under regular operation of the plan, triggered pension plan settlement accounting, resulting in a $761,000 settlement charge, which is reflected in the Corporation's CONSOLIDATED STATEMENTS OF INCOME in the line titled "Salaries and employee benefits." The accumulated benefit obligation for all defined benefit plans was $73,193,000 and $82,157,000 at December 31, 2018 and 2017 , respectively. Information for pension plans with an accumulated benefit obligation in excess of plan assets consists solely of the non-qualified plans for certain employees, former employees and former non-employee directors, and is included in the table below. December 31, 2018 December 31, 2017 Projected benefit obligation $ 3,481 $ 4,604 Accumulated benefit obligation $ 3,481 $ 4,604 Fair value of plan assets $ — $ — The Corporation recognized expense under these non-qualified plans of $161,000 , $213,000 and $217,000 for 2018, 2017 and 2016, respectively. The following table shows the components of net periodic pension benefit cost: December 31, 2018 December 31, 2017 December 31, 2016 Service cost $ 8 $ 10 $ 9 Interest cost 2,816 3,353 3,273 Expected return on plan assets (4,891 ) (4,778 ) (4,508 ) Amortization of prior service cost 87 90 79 Amortization of net loss 287 1,218 1,656 Settlement loss recognized 761 Net periodic pension benefit cost $ (1,693 ) $ 654 $ 509 Other changes in plan assets and benefit obligations recognized in other comprehensive income: December 31, 2018 December 31, 2017 December 31, 2016 Net periodic pension benefit cost $ (1,693 ) $ 654 $ 509 Net gain (loss) (2,189 ) 1,504 (228 ) Amortization of net loss 287 1,979 1,656 Amortization of prior service cost 87 90 79 Total recognized in other comprehensive income (loss) (1,815 ) 3,573 1,507 Total recognized in net periodic pension benefit cost and other comprehensive income (loss) $ (122 ) $ 2,919 $ 998 The estimated amounts that will be amortized from accumulated other comprehensive income into net periodic pension benefit cost over the next fiscal year are: December 31, 2018 December 31, 2017 December 31, 2016 Amortization of net loss $ (432 ) $ (830 ) $ (1,208 ) Amortization of prior service cost (87 ) (87 ) (90 ) Total $ (519 ) $ (917 ) $ (1,298 ) Significant assumptions include: December 31, 2018 December 31, 2017 December 31, 2016 Weighted-average Assumptions Used to Determine Benefit Obligation: Discount rate 4.30 % 3.60 % 4.20 % Rate of compensation increase for accruing active participants n/a n/a 3.00 % Weighted-average Assumptions Used to Determine Cost: Discount rate 3.60 % 4.20 % 4.50 % Expected return on plan assets 6.00 % 6.00 % 6.00 % Rate of compensation increase for accruing active participants n/a n/a 3.00 % At December 31, 2018 and 2017 , 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 ERISA and any other applicable statutes. The plans’ risk management practices include semi-annual 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 individual non-investment grade bonds. At December 31, 2018 , the maturities of the plans’ debt securities ranged from 15 days to 8.24 years , with a weighted average maturity of 4.29 years . At December 31, 2017 , the maturities of the plans’ debt securities ranged from 15 days to 8.83 years , with a weighted average maturity of 4.53 years . The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid as of December 31, 2018 . The minimum contribution required in 2019 will likely be zero , but the Corporation may decide to make a discretionary contribution during the year. 2019 $ 5,583 2020 5,549 2021 5,429 2022 5,363 2023 5,269 After 2023 24,586 $ 51,779 Plan assets are re-balanced quarterly. At December 31, 2018 and 2017 , plan assets by category are as follows: December 31, 2018 December 31, 2017 Actual Target Actual Target Cash and cash equivalents 3.9 % 3.0 % 6.0 % 3.0 % Equity securities 48.4 50.0 52.4 55.0 Debt securities 45.6 45.0 39.6 40.0 Alternative investments 2.1 2.0 2.0 2.0 100.0 % 100.0 % 100.0 % 100.0 % 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 at the rate of 100 percent for the first 3 percent of base salary contributed by participants and 50 percent of the next 3 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 $5,114,000 , $3,691,000 and $3,441,000 for 2018 , 2017 and 2016 , respectively. The Corporation maintained a post retirement benefit plan that provided health insurance benefits to retirees. The plan allowed retirees to be carried under the Corporation’s health insurance plan, generally from ages 55 to 65 . The retirees paid 100 percent of the premiums due for their coverage. In 2016, the Corporation elected to terminate this plan effective December 31, 2017, resulting in no obligation payable under the plan as of December 31, 2017. As a result of the termination, in 2016, the Corporation recognized a curtailment gain of $2,157,000 as a component of "Salaries and benefits expense" in the accompanying CONSOLIDATED STATEMENTS OF INCOME. Post retirement plan expense totaled $(301,000) and $(2,437,000) for the years ending December 31, 2017 and 2016 , 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 $71,277,000 and $78,280,000 as of December 31, 2018 and 2017 , respectively, 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 $5,459,000 and $6,933,000 as of December 31, 2018 and 2017 , respectively, and include governmental agencies, taxable municipal bonds and notes, 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, 2018 and 2017 . Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs December 31, 2018 Fair Value (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 3,026 $ 3,026 Corporate Bonds and Notes 16,691 16,691 Government Agency and Municipal Bonds and Notes 4,479 $ 4,479 Certificates of Deposit 980 980 Party-in-Interest Investments Common Stock 2,073 2,073 Mutual Funds Taxable Bond 12,817 12,817 Large Cap Equity 18,269 18,269 Mid Cap Equity 8,735 8,735 Small Cap Equity 4,713 4,713 International Equity 3,336 3,336 Specialty Alternative Equity 1,617 1,617 $ 76,736 $ 71,277 $ 5,459 Fair Value Measurements Using Quoted Prices in Significant Other Observable Inputs Significant December 31, 2017 Fair Value (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 5,123 $ 5,123 Corporate Bonds and Notes 14,598 14,598 Government Agency and Municipal Bonds and Notes 5,679 $ 5,679 Certificates of Deposit 1,254 1,254 Party-in-Interest Investments Common Stock 2,545 2,545 Mutual Funds Taxable Bond 12,198 12,198 Large Cap Equity 22,137 22,137 Mid Cap Equity 10,676 10,676 Small Cap Equity 5,264 5,264 International Equity 4,030 4,030 Specialty Alternative Equity 1,709 1,709 $ 85,213 $ 78,280 $ 6,933

Income Tax

Income Tax	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Tax	INCOME TAX The reconciliation between income tax expense expected at the U.S. federal statutory tax rate and the reported income tax expense is summarized in the following table for years ended December 31, 2018 , 2017 , 2016 : 2018 2017 2016 Reconciliation of Federal Statutory to Actual Tax Expense: Federal Statutory Income Tax at 21% for 2018 and 35% for 2017 and 2016 $ 39,509 $ 46,758 $ 38,031 Tax-exempt Interest Income (8,347 ) (11,127 ) (8,749 ) Stock Compensation (622 ) (893 ) (61 ) Earnings on Life Insurance (868 ) (2,302 ) (1,486 ) Tax Credits (615 ) (811 ) (564 ) Tax Cuts and Jobs Act - Rate Reform Impact 5,120 Other (58 ) 779 438 Income Tax Expense $ 28,999 $ 37,524 $ 27,609 Effective Tax Rate 15.4 % 28.1 % 25.4 % Income tax expense consists of the following components for the years ended December 31, 2018 , 2017 , 2016 : 2018 2017 2016 Income Tax Expense for the Year Ended December 31: Currently Payable: Federal 23,633 $ 22,001 $ 18,998 State 1,842 Deferred: Federal 6,723 9,969 8,233 Tax Cuts and Jobs Act - Rate Reform Impact 5,120 State (3,199 ) 434 378 Income Tax Expense $ 28,999 $ 37,524 $ 27,609 Significant components of the net deferred tax assets (liabilities) resulting from temporary differences were as follows at December 31, 2018 and 2017 : 2018 2017 Deferred Tax Asset at December 31: Assets: Differences in Accounting for Loan Losses $ 19,785 $ 19,526 Differences in Accounting for Loan Fees 749 1,458 Differences in Accounting for Loans and Securities 710 3,681 Deferred Compensation 2,101 4,448 Federal & State Income Tax Loss Carryforward and Credits 6,954 10,829 Net Unrealized Loss on Securities Available for Sale 1,686 Other 2,028 365 Total Assets 34,013 40,307 Liabilities: Differences in Depreciation Methods 6,496 5,245 Difference in Accounting for Pensions and Other Employee Benefits 566 823 State Income Tax 791 58 Net Unrealized Gain on Securities Available for Sale 2,898 Gain on FDIC Modified Whole Bank Transaction 487 602 Other 4,271 3,897 Total Liabilities 12,611 13,523 Net Deferred Tax Asset Before Valuation Allowance 21,402 26,784 Valuation allowance: Beginning Balance (6,966 ) (9,815 ) Decrease/(Increase) During the Year 6,966 2,849 Ending Balance — (6,966 ) Net Deferred Tax Asset $ 21,402 $ 19,818 The $1,584,000 increase in the Corporation’s net deferred tax asset was due to a combination of a decrease in deferred tax assets and liabilities offset by a decrease in the valuation allowance. The largest net deferred tax asset increase was associated with the release of the $6,966,000 valuation allowance previously recorded against state deferred tax assets. Additionally, the net change in deferred taxes associated with accounting for unrealized gains and losses on available for sale securities increased the net deferred tax asset by $4,584,000 . Offsetting these increases were deferred tax asset decreases associated with federal and state net operating loss carryforwards, accounting for loans and deferred compensation of $3,875,000 , $2,971,000 and $2,347,000 , respectively. As of December 31, 2018 , the Corporation has approximately $31,183,000 of state NOL carryforwards available to offset future state taxable income, which will expire beginning in 2020 . These NOL carryforwards along with normal timing differences between book and tax result in total state deferred tax assets of $3,767,000 . Management believes it is more likely than not that the benefit of these state NOL carryforwards and other state deferred tax assets will be fully realized. Therefore, the Corporation has relieved the previously recorded valuation allowance. The Corporation has additional paid-in capital that is considered restricted resulting from the acquisitions of CFS and Ameriana of approximately $13,393,000 and $11,883,000 , respectively. CFS and Ameriana qualified as banks under provisions of the Internal Revenue Code which permitted them 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, 2018 , would have been approximately $5,308,000 . The Corporation or one of its subsidiaries files income tax returns in the U.S. federal jurisdiction and various state jurisdictions. The Corporation is generally no longer subject to U.S. federal, state and local income tax examinations by tax authorities for tax years before 2015 .

Net Income Per Share

Net Income Per Share	12 Months Ended
	Dec. 31, 2018
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: 2018 2017 2016 Weighted-Average Shares Weighted-Average Shares Weighted-Average Shares Basic net income per share: Net income available to common stockholders $ 159,139 49,262,015 $ 3.23 $ 96,070 45,181,221 $ 2.13 $ 81,051 40,767,343 $ 1.99 Effect of dilutive stock options and restricted stock awards 208,908 221,757 245,790 Diluted net income per share: Net income available to common stockholders $ 159,139 49,470,923 $ 3.22 $ 96,070 45,402,978 $ 2.12 $ 81,051 41,013,133 $ 1.98 As of December 31, 2018 and 2017, there were no stock options with an option price greater than the average market price of the common shares. Options to purchase 51,949 shares of common stock, with a weighted average exercise price of $19.26 at December 31, 2016, 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 Operations

Quarterly Results of Operations (Unaudited)	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 : 2018 2017 First Second Third Fourth First Second Third Fourth Interest income $ 93,620 $ 100,871 $ 104,800 $ 108,653 $ 68,234 $ 71,467 $ 84,847 $ 90,348 Interest expense 13,704 16,300 18,314 20,769 7,235 8,367 10,427 11,583 Net interest income 79,916 84,571 86,486 87,884 60,999 63,100 74,420 78,765 Provision for loan losses 2,500 1,663 1,400 1,664 2,385 2,875 2,083 1,800 Net interest income after provision for loan losses 77,416 82,908 85,086 86,220 58,614 60,225 72,337 76,965 Non-interest income 19,561 18,191 19,527 19,180 14,846 18,434 18,668 19,061 Non-interest expense 53,687 53,504 55,022 57,738 43,099 47,316 58,708 56,433 Income before income tax expense 43,290 47,595 49,591 47,662 30,361 31,343 32,297 39,593 Income tax expense 6,611 7,961 8,478 5,949 7,168 7,207 7,939 15,210 Net income available to common stockholders $ 36,679 $ 39,634 $ 41,113 $ 41,713 $ 23,193 $ 24,136 $ 24,358 $ 24,383 Basic EPS $ 0.75 $ 0.80 $ 0.83 $ 0.85 $ 0.57 $ 0.57 $ 0.50 $ 0.49 Diluted EPS $ 0.74 $ 0.80 $ 0.83 $ 0.85 $ 0.56 $ 0.57 $ 0.50 $ 0.49 Average Shares Outstanding: Basic 49,192,647 49,252,580 49,286,945 49,314,276 40,984,481 42,038,824 48,431,880 49,144,310 Diluted 49,427,972 49,451,406 49,492,019 49,511,233 41,220,586 42,243,539 48,643,774 49,379,303

Condensed Financial Information

Condensed Financial Information (parent company only)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information 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 December 31, 2018 December 31, 2017 Assets Cash $ 87,435 $ 31,527 Investment in subsidiaries 1,459,036 1,411,360 Investment securities 31 Premises and equipment 1,158 1,252 Interest receivable 6 5 Goodwill 448 448 Cash surrender value of life insurance 810 787 Other assets 5,240 3,480 Total assets $ 1,554,133 $ 1,448,890 Liabilities Subordinated debentures and term loans $ 138,463 $ 138,241 Interest payable 994 968 Other liabilities 6,416 6,218 Total liabilities 145,873 145,427 Stockholders' equity 1,408,260 1,303,463 Total liabilities and stockholders' equity $ 1,554,133 $ 1,448,890 Condensed Statements of Income and Comprehensive Income December 31, 2018 December 31, 2017 December 31, 2016 Income Dividends from subsidiaries $ 100,954 $ 33,014 $ 33,546 Loss on sale of available for sale securities (50 ) Other income 572 350 143 Total income 101,526 33,314 33,689 Expenses Interest expense 8,233 7,572 7,185 Salaries and employee benefits 3,729 4,118 639 Net occupancy and equipment expenses 851 797 832 Other outside services 489 1,810 967 Professional services 270 442 279 Other expenses 442 (385 ) (470 ) Total expenses 14,014 14,354 9,432 Income before income tax benefit and equity in undistributed income of subsidiaries 87,512 18,960 24,257 Income tax benefit 3,298 5,946 3,243 Income before equity in undistributed income of subsidiaries 90,810 24,906 27,500 Equity in undistributed income of subsidiaries 68,329 71,164 53,551 Net income available to common stockholders $ 159,139 $ 96,070 $ 81,051 Net income $ 159,139 $ 96,070 $ 81,051 Other comprehensive income (loss) (17,888 ) 10,673 (12,219 ) Comprehensive income $ 141,251 $ 106,743 $ 68,832 Condensed Statement of Cash Flows December 31, 2018 December 31, 2017 December 31, 2016 Cash Flow From Operating Activities: Net income $ 159,139 $ 96,070 $ 81,051 Adjustments to Reconcile Net Income to Net Cash: Share-based compensation 1,256 1,215 1,166 Distributions in excess of (equity in undistributed) income of subsidiaries (68,329 ) (71,164 ) (53,551 ) Loss on sale of available for sale securities 50 Net Change in: Other assets 584 3,358 833 Other liabilities 274 (1,900 ) 849 Investment in subsidiaries - operating activities 841 1,112 (1,938 ) Net cash provided by operating activities 93,765 28,741 28,410 Cash Flow From Investing Activities: Purchase of securities available for sale (19,804 ) Net cash received in acquisition 37 Other 2,189 Net cash provided (used) in investing activities 2,189 37 (19,804 ) Cash Flow From Financing Activities: Cash dividends (41,660 ) (31,820 ) (22,203 ) Stock issued under employee benefit plans 707 519 462 Stock issued under dividend reinvestment and stock purchase plan 1,211 991 835 Stock options exercised 1,598 2,398 2,602 Stock redeemed (1,902 ) (1,283 ) (1,980 ) Net cash used by financing activities (40,046 ) (29,195 ) (20,284 ) Cash, beginning of the year 31,527 31,944 43,622 Cash, end of year $ 87,435 $ 31,527 $ 31,944

Accounting Matters

Accounting Matters	12 Months Ended
	Dec. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Accounting Matters	ACCOUNTING MATTERS The Corporation continually monitors potential accounting changes and pronouncements. The following pronouncements have been deemed to have the most applicability to the Corporation's financial statements: FASB Accounting Standards Updates No. 2018-14 - Compensation - Retirement Benefits - Defined Benefit Plans - General (Subtopic 715-20): Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans Summary - The FASB has issued ASU No. 2018-14, Compensation - Retirement Benefits - Defined Benefit Plans - General (Subtopic 715-20): Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans, that applies to all employers that sponsor defined benefit pension or other postretirement plans. The amendments modify the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. Disclosure Requirements Deleted * The amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit cost over the next fiscal year. * The amount and timing of plan assets expected to be returned to the employer. * Related party disclosures about the amount of future annual benefits covered by insurance and annuity contracts and significant transactions between the employer or related parties and the plan. * For public entities, the effects of a one-percentage-point change in assumed health care cost trend rates on the (a) aggregate of the service and interest cost components of net periodic benefit costs and (b) benefit obligation for postretirement health care benefits. Disclosure Requirements Added * An explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period. The amendments also clarify the disclosure requirements in paragraph 715-20-50-3, which state that the following information for defined benefit pension plans should be disclosed: * The projected benefit obligation (PBO) and fair value of plan assets for plans with PBOs in excess of plan assets. * The accumulated benefit obligation (ABO) and fair value of plan assets for plans with ABOs in excess of plan assets. ASU No. 2018-14 is effective for fiscal years ending after December 15, 2020, for public business entities and for fiscal years ending after December 15, 2021, for all other entities. Early adoption is permitted for all entities. The Corporation plans to adopt the standard in the first quarter of 2020, but adoption of the standard is not expected to have a significant impact on the Corporation’s disclosures. FASB Accounting Standards Updates No. 2018-13 - Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement Summary - The FASB has issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement. ASU No. 2018-13 modifies the disclosure requirements on fair value measurements in Topic 820. Certain disclosure requirements related to transfers between Level 1 and Level 2 of the fair value hierarchy and Level 3 valuation process were removed from Topic 820. Disclosures were also added to Topic 820 for changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. In addition, the amendments eliminate at a minimum from the phrase “an entity shall disclose at a minimum” to promote the appropriate exercise of discretion by entities when considering fair value measurement disclosures and to clarify that materiality is an appropriate consideration of entities and their auditors when evaluating disclosure requirements. The amendments in ASU No. 2018-13 are effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. Early adoption is permitted. An entity is permitted to early adopt any removed or modified disclosures upon issuance of ASU No. 2018-13 and delay adoption of the additional disclosures until their effective date. The Corporation plans to adopt the standard in the first quarter of 2020, but adoption of the standard is not expected to have a significant impact on the Corporation’s disclosures. FASB Accounting Standards Updates No. 2018-11 - Leases (Topic 842): Targeted Improvements Summary - The FASB has issued Accounting Standards Update (ASU) No. 2018-11, Leases (Topic 842): Targeted Improvements. This ASU is intended to reduce costs and ease implementation of the leases standard for financial statement preparers. ASU 2018-11 provides a new transition method and a practical expedient for separating components of a contract. The amendments ASU 2018-11 provide entities with an additional (and optional) transition method to adopt the new leases standard. Under this new transition method, an entity initially applies the new leases standard at the adoption date and recognizes a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption consistent with preparers’ requests. Consequently, an entity’s reporting for the comparative periods presented in the financial statements in which it adopts the new leases standard will continue to be in accordance with current GAAP in Topic 840, Leases. An entity that elects this additional (and optional) transition method must provide the required Topic 840 disclosures for all periods that continue to be in accordance with Topic 840. The amendments do not change the existing disclosure requirements in Topic 840 (for example, they do not create interim disclosure requirements that entities previously were not required to provide). The Corporation adopted this new transition method on January 1, 2019, but did not recognize a cumulative-effect adjustment to the opening balance of retained earnings at adoption. The amendments in ASU 2018-11 provide lessors with a practical expedient, by class of underlying asset, to not separate non-lease components from the associated lease component and, instead, to account for those components as a single component if the non-lease components otherwise would be accounted for under the new revenue guidance (Topic 606) and both of the following are met: * The timing and pattern of transfer of the non-lease component(s) and associated lease component are the same. * The lease component, if accounted for separately, would be classified as an operating lease. An entity electing this practical expedient (including an entity that accounts for the combined component entirely in Topic 606) is required to disclose certain information, by class of underlying asset, as specified in the ASU. The Corporation elected the practical expedient to not separate non-lease components from the associated lease component at adoption, which was January 1, 2019. The amendments in ASU 2018-11 related to separating components of a contract affect the amendments in ASU No. 2016-02, which are not yet effective but can be early adopted. For entities that have not adopted Topic 842 before the issuance of this ASU, the effective date and transition requirements for the amendments in this update related to separating components of a contract are the same as the effective date and transition requirements in ASU 2016-02. For entities that have adopted Topic 842 before the issuance of ASU 2018-11, the transition and effective date of the amendments related to separating components of a contract in this ASU are as follows: * The practical expedient may be elected either in the first reporting period following the issuance of this ASU or at the original effective date of Topic 842 for that entity. * The practical expedient may be applied either retrospectively or prospectively. All entities that elect the practical expedient related to separating components of a contract in this ASU must apply the expedient, by class of underlying asset, to all existing lease transactions that qualify for the expedient at the date elected. FASB Accounting Standards Update No. 2018-07 - Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting Summary - The FASB has issued an Accounting Standards Update (ASU) intended to reduce cost and complexity and to improve financial reporting for non-employee share-based payments. The ASU expands the scope of Topic 718, Compensation-Stock Compensation (which currently only includes share-based payments to employees) to include share-based payments issued to non-employees for goods or services. Consequently, the accounting for share-based payments to non-employees and employees will be substantially aligned. The ASU supersedes Subtopic 505-50, Equity-Equity-Based Payments to Non-Employees. The amendments in this ASU are effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. For all other companies, the amendments are effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. Early adoption is permitted, but no earlier than a company’s adoption date of Topic 606, Revenue from Contracts with Customers. The Corporation adopted the standard in the first quarter of 2019 and adoption of the standard did not have a significant effect on the Corporation’s consolidated financial statements. FASB Accounting Standards Update No. 2017-08 - Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities Summary - The FASB has issued Accounting Standards Update (ASU) No. 2017-08, Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities . The ASU shortens the amortization period for certain callable debt securities held at a premium to the earliest call date. Under current GAAP, entities normally amortize the premium as an adjustment of yield over the contractual life of the instrument. Stakeholders have expressed concerns with the current approach on the basis that current GAAP excludes certain callable debt securities from consideration of early repayment of principal even if the holder is certain that the call will be exercised. As a result, upon the exercise of a call on a callable debt security held at a premium, the unamortized premium is recorded as a loss in earnings. Further, there is diversity in practice (1) in the amortization period for premiums of callable debt securities, and (2) in how the potential for exercise of a call is factored into current impairment assessments. Another issue is that the practice in the United States is to quote, price, and trade callable debt securities assuming a model that incorporates consideration of calls (also referred to as “yield-to-worst” pricing). The ASU shortens the amortization period for certain callable debt securities held at a premium and requires the premium to be amortized to the earliest call date. However, the amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. The amendments are effective for public business entities for annual periods beginning after December 15, 2018, including interim periods within those annual periods. For other entities, the amendments are effective for annual periods beginning after December 15, 2019, and interim periods within annual periods beginning after December 15, 2020. Early adoption is permitted. Entities are required to apply the amendments on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The entity is required to provide disclosures about a change in accounting principle in the period of adoption. The Corporation adopted ASU 2017-08 on January 1, 2019 and adoption of the standard did not have a significant effect on the Corporation’s consolidated financial statements. FASB Accounting Standards Update No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Summary - The FASB has issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . This new guidance was issued to address concerns that current generally accepted accounting principles (GAAP) restricts the ability to record credit losses that are expected, but do not yet meet the “probable” threshold by replacing the current “incurred loss” model for recognizing credit losses with an “expected life of loan loss” model referred to as the Current Expected Credit Loss (CECL) model. Under the CECL model, certain financial assets carried at amortized cost, such as loans held for investment and held-to-maturity debt securities, are required to be presented at the net amount expected to be collected. The measurement of expected credit losses is to be based on information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. This measurement will take place at the time the financial asset is first added to the balance sheet and periodically thereafter. This differs significantly from the “incurred loss” model required under current GAAP, which delays recognition until it is probable a loss has been incurred. The change could materially affect how the allowance for loan losses is determined and cause a charge to earnings through the provision for loan losses. Such would adversely affect the financial condition of the Corporation. The ASU is effective for SEC filers for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019 (i.e., January 1, 2020, for calendar year entities). Early application will be permitted for all organizations for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Corporation plans to adopt this ASU in the first quarter of 2020. The Corporation expects a one-time cumulative-effect adjustment to the allowance for loan losses will be recognized in retained earnings on the consolidated balance sheet as of the beginning of the first reporting period in which the new standard is effective, as is consistent with regulatory expectations set forth in interagency guidance issued at the end of 2016. The Corporation established an implementation team that meets on a regular basis to oversee activities and monitor progress. Third party software has been implemented and model development is in progress. The magnitude of any such adjustment or the overall impact of the new standard on the financial condition or results of operations cannot yet be determined. FASB Accounting Standards Update No. 2016-02 - Leases (Topic 842) Summary - The FASB has issued its new lease accounting guidance in Accounting Standards Update (ASU) No. 2016-02, Leases (Topic 842). Under the new guidance, lessees will be required to recognize the following for all leases (with the exception of short-term leases) at the commencement date: • A lease liability, which is a lessee‘s obligation to make lease payments arising from a lease, measured on a discounted basis; and • A right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. Under the new guidance, lessor accounting is largely unchanged. Certain targeted improvements were made to align, where necessary, lessor accounting with the lessee accounting model and Topic 606, Revenue from Contracts with Customers. The new lease guidance simplified the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off-balance sheet financing. Public business entities should apply the amendments in ASU 2016-02 for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years (i.e., January 1, 2019, for a calendar year entity). Nonpublic business entities should apply the amendments for fiscal years beginning after December 15, 2019 (i.e., January 1, 2020, for a calendar year entity), and interim periods within fiscal years beginning after December 15, 2020. Early application is permitted for all public business entities and all nonpublic business entities upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. The Corporation adopted this ASU on January 1, 2019 and recorded a right-of-use asset of $23.3 million and a lease liability of $23.8 million at adoption.

General Litigation

General Litigation	12 Months Ended
	Dec. 31, 2018
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, 2018
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS MBT Financial Corp. On October 9, 2018, the Corporation and MBT Financial Corp., a Michigan corporation ("MBT"), entered into an Agreement and Plan of Reorganization and Merger (the "Merger Agreement"), pursuant to which MBT will, subject to the terms and conditions of the Merger Agreement, merge with and into the Corporation (the "Holding Company Merger"), whereupon the separate corporate existence of MBT will cease and the Corporation will survive. Immediately following the Holding Company Merger, MBT's wholly-owned subsidiary, Monroe Bank & Trust, will be merged with and into the Bank (the "Bank Merger" and, together with the Holding Company Merger, the "Mergers"), with the Bank continuing as the surviving bank. Based on the closing price of the Corporation's common stock on October 9, 2018 of $45.71 per share, the transaction value is estimated at approximately $290.9 million . The transaction is expected to be a tax-free exchange for MBT's shareholders who will be receiving the Corporation's common stock pursuant to the Holding Company Merger. MBT's total assets as of December 31, 2018 were $1.3 billion . At a special meeting held on February 14, 2019, the shareholders of MBT approved the Merger Agreement and the transactions contemplated by the Merger Agreement. In addition, on January 3, 2019, the FDIC issued its order approving the Bank Merger, subject to certain customary conditions, and on February 18, 2019, the Indiana DFI approved the Bank Merger. However, consummation of the Mergers remain subject to the (i) receipt of a waiver by the Federal Reserve Board of Governors relating to its right to receive an application in connection with the Holding Company Merger, and (ii) satisfaction of other customary closing conditions contained in the Merger Agreement. The Mergers are expected to close during the first half of 2019.

Nature of Operations and Summ_2

Nature of Operations and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Accounting	The accounting and reporting policies of the Corporation and the Bank, conform to accounting principles generally accepted in the United States of America and reporting practices followed by the banking industry. 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 and Held to Maturity 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 OTTI at least on a quarterly basis, and more frequently when economic or market conditions warrant such an evaluation. In determining OTTI, 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 an other-than-temporary decline exists involves a high degree of subjectivity and judgment and is based on the information available to management at a point in time. When OTTI occurs, the amount of OTTI recognized in the income statement depends on whether the Corporation intends to sell the security 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. 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 shall be 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. If the intent is not to sell the security and it is not more likely than not that the Corporation will be required to sell the security before the recovery of its amortized cost basis less any recognized credit loss, the OTTI has been separated into the amount representing the credit loss and the amount related to all other factors. 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 is 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. 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 loan portfolio are carried at the principal amount outstanding, net of unearned income and principal charge-offs. Certain non-accrual, substantially delinquent and renegotiated loans classified as troubled debt restructures may be considered to be impaired in accordance with ASC 310, Receivables . Under ASC 310-10, a loan is impaired when, based on current information or events, it is probable all amounts due (principal and interest) according to the contractual terms of the loan agreement are uncollectible. Renegotiated consumer loans classified as troubled debt restructures are considered to be impaired. In applying the provisions of ASC 310-10, the Corporation considers all other investments in one-to-four family residential loans and consumer installment loans to be homogeneous and therefore excluded from separate identification for evaluation of impairment. Impaired loans are carried at the fair value of collateral if the loan is collateral dependent, or the present value of estimated future cash flows using the loan’s existing rate. 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. Interest income is accrued on the principal balances of loans. The accrual of interest is discontinued on a loan when, in management’s opinion, the borrower may be unable to meet payments as they become due. When the interest accrual is discontinued, all unpaid accrued interest is reversed against earnings when considered uncollectible. 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. Loan commitments and letters-of-credit generally have short-term, variable-rate features and contain clauses which limit the 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 purchased credit impaired. Evidence of credit quality deterioration as of purchase dates may include information such as past-due and nonaccrual status, borrower credit risk grade and recent loan to value percentages. Purchased 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 individually evaluated for the initial fair value measurement. Accordingly, allowances for credit losses related to these loans are not carried over at the acquisition date. 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. Acquired loans not accounted for under ASC 310-30 are accounted for under ASC 310-20, which allows the fair value adjustment to be accreted into income over the remaining life of the loans.
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 is confirmed. Subsequent recoveries, if any, are credited to the allowance. The Corporation’s strategy for credit risk management includes 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 regional geographic and industry levels, 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 impaired loans accounted for under ASC 310-10, 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. 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. Loans individually evaluated for impairment are those deemed impaired in accordance with ASC 310-10, including commercial relationships greater than $500,000 that exhibit well defined credit weaknesses. Any allowances for impaired loans are measured based on the fair value of the underlying collateral if collateral dependent or the present value of expected future cash flows discounted at the loan’s effective interest rate. The Corporation evaluates the collectability of principal 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 20. PENSION AND OTHER POST RETIREMENT BENEFIT PLANS of these Notes to Consolidated Financial Statements.
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 Home Loan Bank Stock	FEDERAL HOME LOAN BANK STOCK is a required investment for institutions that are members of the FHLB. The Bank is a member of the FHLB of Indianapolis. Members are required to own a certain amount of stock based on the level of borrowings and other factors, and may invest in additional amounts. FHLB stock is 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 two 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, Intangibles – Goodwill and Other . 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, 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 to offset a portion of the employee benefit costs. 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. Changes in cash surrender values and death benefits received in excess of cash surrender values are reported in non-interest income. A corporate policy is in place with defined thresholds that limit the amount of credit, interest rate and liquidity risk inherent in a BOLI portfolio. The Corporation actively monitors the overall portfolio performance along with the credit quality of the insurance carriers and the credit quality and yield of the underlying investments.
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 other real estate owned and foreclosure expenses.
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 AOCI 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: (1) a hedge of the fair value of the recognized asset or liability or of an unrecognized firm commitment (a fair value hedge); or (2) 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 AOCI to the extent the hedge is effective. The gains and losses on derivative instruments that are reported in AOCI 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 in the consolidated statements of income. 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, Fair Value Measurements and Disclosures ), 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 is generally no longer subject to U.S. federal, state and local income tax examinations by tax authorities for tax years before 2015 . 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 Corporation's policy is to recognize interest and penalties related to unrecognized tax benefits, if any, as a component of income tax expense.
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.
Recent Accounting Changes	Recent Accounting Changes ASU 2018-02 "Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income" ("ASU 2018-02") allows a reclassification from accumulated other comprehensive income (loss) to retained earnings for the stranded tax effects caused by the revaluation of deferred taxes resulting from the newly enacted corporate tax rate in the Tax Cuts and Jobs Act. The ASU is effective in years beginning after December 15, 2018, but permits early adoption in a period for which financial statements have not yet been issued. The Corporation elected to early adopt the ASU as of January 1, 2018. The adoption of the guidance resulted in an insignificant cumulative-effect adjustment that decreased accumulated other comprehensive income (loss) and increased retained earnings in 2018. ASU 2017-12 - "Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities" ("ASU 2017-12") is intended to improve and simplify accounting rules around hedge accounting. The ASU is effective for public companies in 2019 and private companies in 2020. Early adoption is permitted. The new standard refines and expands hedge accounting for both financial (e.g., interest rate) and commodity risks. Its provisions create more transparency around how economic results are presented, both on the face of the financial statements and in the footnotes, for investors and analysts. The new standard takes effect for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, for public companies and for fiscal years beginning after December 15, 2019 (and interim periods for fiscal years beginning after December 15, 2020), for private companies. Early adoption is permitted in any interim period or fiscal years before the effective date of the standard. ASU 2017-12 requires a modified retrospective transition method in which a cumulative effect of the change on the opening balance of each affected component of equity is recognized in the statement of financial position as of the date of adoption. The Corporation adopted this standard in the third quarter of 2018. As permitted by the ASU, the Corporation reclassified $30.8 million of state and municipal securities with unrealized gains of $450,000 from the held to maturity portfolio to the available for sale portfolio. Other than this reclassification of securities, adoption of the standard did not have a significant impact on the Corporation’s consolidated financial statements. ASU 2017-07 " Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost" ("ASU 2017-07") applies to all employers, including not-for-profit entities, that offer to their employees defined benefit pension plans, other postretirement benefit plans, or other types of benefits accounted for under Topic 715, Compensation - Retirement Benefits . The amendments require that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. If a separate line item or items are used to present the other components of net benefit cost, that line item or items must be appropriately described. If a separate line item or items are not used, the line item or items used in the income statement to present the other components of net benefit cost must be disclosed. The amendments also allow only the service cost component to be eligible for capitalization when applicable (e.g., as a cost of internally manufactured inventory or a self-constructed asset). The amendments are effective for public business entities for annual periods beginning after December 15, 2017, including interim periods within those annual periods. For other entities, the amendments are effective for annual periods beginning after December 15, 2018, and interim periods within annual periods beginning after December 15, 2019. Early adoption is permitted as of the beginning of an annual period for which financial statements (interim or annual) have not been issued or made available for issuance. The Corporation adopted this ASU in 2018. Adoption of the standard did not have a significant impact on the Corporation’s consolidated financial statements. ASU 2016-15 "Statement of Cash Flows (Topic 230)" ("ASU 2016-15") is intended to reduce the diversity in practice around how certain transactions are classified within the statement of cash flows. ASU 2016-15 became effective for the Corporation on January 1, 2018 and did not have a significant impact on the Corporation's financial statements. ASU 2016-01 "Financial Instruments - Overall (Subtopic 825-10): Recognition of Financial Assets and Financial Liabilities" ("ASU 2016-01") makes targeted amendments to the guidance for recognition, measurement, presentation and disclosure of financial instruments. ASU 2016-01 requires equity investments, other than equity method investments, to be measured at fair value with changes in fair value recognized in net income. The ASU requires a cumulative-effect adjustment to retained earnings as of the beginning of the reporting period of adoption to reclassify the cumulative change in fair value of equity securities previously recognized in accumulated other comprehensive income (loss). ASU 2016-01 became effective for the Corporation on January 1, 2018. The adoption of the guidance did not result in any cumulative effect adjustment in 2018. ASU 2016-01 also emphasizes the existing requirement to use exit prices to measure fair value for disclosure purposes and clarifies that entities should not make use of a practicability exception in determining the fair value of loans. Accordingly, the Corporation refined the calculation used to determine the disclosed fair value of loans held for investment as part of adopting this standard. The refined calculation did not have a significant impact on the fair value disclosures included in NOTE 14. FAIR VALUE OF FINANCIAL INSTRUMENTS of these Notes to Consolidated Condensed Financial Statements. ASU 2014-09 "Revenue from Contracts with Customers (Topic 606)" ("ASU 2014-09") implements a common revenue standard that clarifies the principles for recognizing revenue. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 establishes a five-step model which entities must follow to recognize revenue and removes inconsistencies and weaknesses in existing guidance. The guidance does not apply to revenue associated with financial instruments, including loans and investment securities that are accounted for under other GAAP, which comprises a significant portion of the Corporation's revenue stream. ASU 2014-09 became effective for the Corporation on January 1, 2018. The adoption of ASU 2014-09 did not result in a change to the accounting for any of the in-scope revenue streams; as such, no cumulative effect adjustment was recorded. Additional information related to revenue generated from contracts with customers is detailed below. Revenue Recognition ASU 2014-09 establishes principles for reporting information about the nature, amount, timing and uncertainty of revenue and cash flows arising from the entity's contracts to provide goods or services to customers. The core principle requires an entity to recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration that it expects to be entitled to receive in exchange for those goods or services recognized as performance obligations are satisfied. The majority of the Corporation's revenue-generating transactions are not subject to ASU 2014-09, including revenue generated from financial instruments, such as loans, letters of credit, derivatives and investment securities, as well as revenue related to mortgage servicing activities, as these activities are subject to other GAAP discussed elsewhere within the disclosures. The Corporation has evaluated the nature of its contracts with customers and determined that further disaggregation of revenue from contracts with customers into more granular categories beyond what is presented in the Consolidated Statements of Income was not necessary. Descriptions of revenue-generating activities that are within the scope of ASU 2014-09, which are presented in our income statements are as follows: Service charges on deposit accounts: The Corporation earns fees from its deposit customers for transaction-based, account maintenance and overdraft services. Transaction-based fees, which include services such as ATM use fees, stop payment charges, statement rendering and ACH fees, are recognized at the time the transaction is executed, which is the point in time the Corporation fulfills the customer's request. Account maintenance fees, which relate primarily to monthly maintenance, are earned monthly, representing the period which the Corporation satisfies the performance obligation. Overdraft fees are recognized at the point in time that the overdraft occurs. Service charges on deposits are withdrawn from the customer's account balance. Fiduciary activities : This represents monthly fees due from wealth management customers as consideration for managing the customers' assets. Wealth management and trust services include custody of assets, investment management, fees for trust services and similar fiduciary activities. These fees are primarily earned over time as the Corporation provides the contracted monthly or quarterly services and are generally assessed based on the market value of assets under management at month-end. Fees that are transaction-based are recognized at the point in time that the transaction is executed. Investment Brokerage Fees : The Corporation earns fees from investment brokerage services provided to its customers by a third-party service provider. The Corporation receives commissions from the third-party provider on a monthly basis based upon customer activity for the month. The fees are paid to us by the third party on a monthly basis and are recognized when received. Interchange income : The Corporation earns interchange fees from debit and credit cardholder transactions conducted through the Visa and MasterCard payment networks. Interchange fees from cardholder transactions represent a percentage of the underlying transaction value and are recognized concurrent with the transaction processing services provided to the cardholder. Gains (Losses) on Sales of OREO : The Corporation records a gain or loss from the sale of OREO when control of the property transfers to the buyer, which generally occurs at the time of an executed deed. When the Corporation finances the sale of OREO to the buyer, the Corporation assesses whether the buyer is committed to perform their obligations under the contract and whether collectability of the transaction price is probable. Once these criteria are met, the OREO asset is derecognized and the gain or loss on sale is recorded upon the transfer of control of the property to the buyer. In determining the gain or loss on the sale, the Corporation adjusts the transaction price and related gain (loss) on sale if a significant financing component is present.
Revenue Recognition	Revenue Recognition ASU 2014-09 establishes principles for reporting information about the nature, amount, timing and uncertainty of revenue and cash flows arising from the entity's contracts to provide goods or services to customers. The core principle requires an entity to recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration that it expects to be entitled to receive in exchange for those goods or services recognized as performance obligations are satisfied. The majority of the Corporation's revenue-generating transactions are not subject to ASU 2014-09, including revenue generated from financial instruments, such as loans, letters of credit, derivatives and investment securities, as well as revenue related to mortgage servicing activities, as these activities are subject to other GAAP discussed elsewhere within the disclosures. The Corporation has evaluated the nature of its contracts with customers and determined that further disaggregation of revenue from contracts with customers into more granular categories beyond what is presented in the Consolidated Statements of Income was not necessary. Descriptions of revenue-generating activities that are within the scope of ASU 2014-09, which are presented in our income statements are as follows: Service charges on deposit accounts: The Corporation earns fees from its deposit customers for transaction-based, account maintenance and overdraft services. Transaction-based fees, which include services such as ATM use fees, stop payment charges, statement rendering and ACH fees, are recognized at the time the transaction is executed, which is the point in time the Corporation fulfills the customer's request. Account maintenance fees, which relate primarily to monthly maintenance, are earned monthly, representing the period which the Corporation satisfies the performance obligation. Overdraft fees are recognized at the point in time that the overdraft occurs. Service charges on deposits are withdrawn from the customer's account balance. Fiduciary activities : This represents monthly fees due from wealth management customers as consideration for managing the customers' assets. Wealth management and trust services include custody of assets, investment management, fees for trust services and similar fiduciary activities. These fees are primarily earned over time as the Corporation provides the contracted monthly or quarterly services and are generally assessed based on the market value of assets under management at month-end. Fees that are transaction-based are recognized at the point in time that the transaction is executed. Investment Brokerage Fees : The Corporation earns fees from investment brokerage services provided to its customers by a third-party service provider. The Corporation receives commissions from the third-party provider on a monthly basis based upon customer activity for the month. The fees are paid to us by the third party on a monthly basis and are recognized when received. Interchange income : The Corporation earns interchange fees from debit and credit cardholder transactions conducted through the Visa and MasterCard payment networks. Interchange fees from cardholder transactions represent a percentage of the underlying transaction value and are recognized concurrent with the transaction processing services provided to the cardholder. Gains (Losses) on Sales of OREO : The Corporation records a gain or loss from the sale of OREO when control of the property transfers to the buyer, which generally occurs at the time of an executed deed. When the Corporation finances the sale of OREO to the buyer, the Corporation assesses whether the buyer is committed to perform their obligations under the contract and whether collectability of the transaction price is probable. Once these criteria are met, the OREO asset is derecognized and the gain or loss on sale is recorded upon the transfer of control of the property to the buyer. In determining the gain or loss on the sale, the Corporation adjusts the transaction price and related gain (loss) on sale if a significant financing component is present.

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of Preliminary Valuations of the Fair Value of Assets Acquired and Liabilities Assumed	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 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 Arlington Bank acquisition is detailed in the following table. Fair Value Cash and cash equivalents $ 48,532 Interest-bearing time deposits 292 Loans held for sale 7,626 Loans 224,680 Premises and equipment 1,986 Federal Home Loan Bank stock 1,091 Interest receivable 653 Other assets 1,620 Deposits (252,783 ) Interest payable (244 ) Other liabilities (3,106 ) Net tangible assets acquired 30,347 Core deposit intangible 4,526 Goodwill 47,719 Purchase price $ 82,592 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 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 IAB acquisition is detailed in the following table. Fair Value Cash and cash equivalents $ 6,016 Interest-bearing time deposits 248,212 Investment securities 4,078 Loans held for sale 594 Loans 725,382 Premises and equipment 10,107 Federal Home Loan Bank stock 4,810 Interest receivable 3,445 Cash surrender value of life insurance 26,964 Other assets 11,780 Deposits (862,271 ) Securities sold under repurchase agreements (17,915 ) Federal Home Loan Bank Advances (47,575 ) Subordinated debentures (10,583 ) Interest payable (1,005 ) Other liabilities (14,472 ) Net tangible assets acquired 87,567 Other Intangible assets 17,403 Goodwill 153,636 Purchase price $ 258,606
Schedule of Acquired Loan Data	Acquired loan data for IAB can be found in the table below: Fair Value of Acquired Loans at Acquisition Date Gross Contractual Amounts Receivable at Acquisition Date Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected Acquired receivables subject to ASC 310-30 $ 4,838 $ 14,131 $ 8,352 Acquired receivables not subject to ASC 310-30 $ 720,544 $ 864,613 $ 9,786 Acquired loan data for Arlington Bank can be found in the table below: Fair Value of Acquired Loans at Acquisition Date Gross Contractual Amounts Receivable at Acquisition Date Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected Acquired receivables subject to ASC 310-30 $ 2,625 $ 6,183 $ 2,891 Acquired receivables not subject to ASC 310-30 $ 222,055 $ 308,857 $ 2,741 The following table presents loans acquired during the period ending December 31, 2017, for which it was probable at acquisition that all contractually required payments would not be collected. There were no loans acquired during the period ending December 31, 2018. 2017 IAB Arlington Bank Total Contractually required payments receivable at acquisition date $ 14,131 $ 6,183 $ 20,314 Nonaccretable difference 8,352 2,891 11,243 Expected cash flows at acquisition date 5,779 3,292 9,071 Accretable difference 941 667 1,608 Basis in loans at acquisition date $ 4,838 $ 2,625 $ 7,463
Schedule of Pro Forma Information from Acquisition	The following schedule includes pro forma results for the year ended December 31, 2017 and 2016, as if the Arlington Bank and IAB acquisitions occurred as of the beginning of the periods presented. 2017 2016 Total revenue (net interest income plus other income) $ 380,324 $ 353,732 Net income available to common shareholders $ 95,009 $ 95,288 Earnings per share: Basic $ 1.94 $ 1.95 Diluted $ 1.93 $ 1.94

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Approximate Market Value 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, 2018 U.S. Government-sponsored agency securities $ 13,493 $ 92 $ 3 $ 13,582 State and municipal 605,994 5,995 5,854 606,135 U.S. Government-sponsored mortgage-backed securities 530,209 634 8,396 522,447 Corporate obligations 31 31 Total available for sale 1,149,727 6,721 14,253 1,142,195 Held to maturity at December 31, 2018 U.S. Government-sponsored agency securities 22,618 545 22,073 State and municipal 197,909 2,858 872 199,895 U.S. Government-sponsored mortgage-backed securities 268,860 713 3,323 266,250 Foreign investment 1,000 1 999 Total held to maturity 490,387 3,571 4,741 489,217 Total Investment Securities $ 1,640,114 $ 10,292 $ 18,994 $ 1,631,412 Available for sale at December 31, 2017 U.S. Government-sponsored agency securities State and municipal $ 510,852 $ 16,932 $ 1,091 $ 526,693 U.S. Government-sponsored mortgage-backed securities 473,325 964 3,423 470,866 Corporate obligations 31 31 Equity securities 2,357 2,357 Total available for sale 986,565 17,896 4,514 999,947 Held to maturity at December 31, 2017 U.S. Government-sponsored agency securities 22,618 435 22,183 State and municipal 235,594 6,295 244 241,645 U.S. Government-sponsored mortgage-backed securities 301,443 3,341 1,404 303,380 Foreign investment 1,000 1,000 Total held to maturity 560,655 9,636 2,083 568,208 Total Investment Securities $ 1,547,220 $ 27,532 $ 6,597 $ 1,568,155
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, 2018 and 2017 : Less than 12 Months 12 Months or Longer Total Fair Gross Fair Gross Fair Gross Temporarily Impaired Available for Sale Securities at December 31, 2018 U.S. Government-sponsored agency securities $ 1,490 $ 3 $ 1,490 $ 3 State and municipal 234,431 3,958 $ 38,028 $ 1,896 272,459 5,854 U.S. Government-sponsored mortgage-backed securities 196,601 2,400 217,121 5,996 413,722 8,396 Total Temporarily Impaired Available for Sale Securities 432,522 6,361 255,149 7,892 687,671 14,253 Temporarily Impaired Held to Maturity Securities at December 31, 2018 U.S. Government-sponsored agency securities 22,073 545 22,073 545 State and municipal 14,952 369 16,786 503 31,738 872 U.S. Government-sponsored mortgage-backed securities 102,828 876 87,268 2,447 190,096 3,323 Foreign investment 999 1 999 1 Total Temporarily Impaired Held to Maturity Securities 117,780 1,245 127,126 3,496 $ 244,906 4,741 Total Temporarily Impaired Investment Securities $ 550,302 $ 7,606 $ 382,275 $ 11,388 $ 932,577 $ 18,994 Less than 12 Months 12 Months or Longer Total Fair Gross Fair Gross Fair Gross Temporarily Impaired Available for Sale Securities at December 31, 2017 State and municipal $ 13,296 $ 198 $ 35,324 $ 893 $ 48,620 $ 1,091 U.S. Government-sponsored mortgage-backed securities 182,755 1,520 68,667 1,903 251,422 3,423 Total Temporarily Impaired Available for Sale Securities 196,051 1,718 103,991 2,796 300,042 4,514 Temporarily Impaired Held to Maturity Securities at December 31, 2017 U.S. Government-sponsored agency securities 9,988 131 12,196 304 22,184 435 State and municipal 2,430 36 15,805 208 18,235 244 U.S. Government-sponsored mortgage-backed securities 62,508 485 43,078 919 105,586 1,404 Total Temporarily Impaired Held to Maturity Securities 74,926 652 71,079 1,431 146,005 2,083 Total Temporarily Impaired Investment Securities $ 270,977 $ 2,370 $ 175,070 $ 4,227 $ 446,047 $ 6,597
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, 2018 Due in one year or less $ 13,092 $ 13,144 $ 4,732 $ 4,730 Due after one through five years 5,311 5,378 49,054 48,473 Due after five through ten years 73,280 74,411 62,873 64,163 Due after ten years 527,835 526,815 104,868 105,601 619,518 619,748 221,527 222,967 U.S. Government-sponsored mortgage-backed securities 530,209 522,447 268,860 266,250 Total Investment Securities $ 1,149,727 $ 1,142,195 $ 490,387 $ 489,217

Loans and Allowance (Tables)

Loans and Allowance (Tables)	12 Months Ended
	Dec. 31, 2018
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: December 31, 2018 December 31, 2017 Commercial and industrial loans $ 1,726,664 $ 1,493,493 Agricultural production financing and other loans to farmers 92,404 121,757 Real estate loans: Construction 545,729 612,219 Commercial and farmland 2,832,102 2,562,691 Residential 966,421 962,765 Home equity 528,157 514,021 Individuals' loans for household and other personal expenditures 99,788 86,935 Lease financing receivables, net of unearned income 1,600 2,527 Other commercial loans 431,602 394,791 Loans 7,224,467 6,751,199 Allowance for loan losses (80,552 ) (75,032 ) Net Loans $ 7,143,915 $ 6,676,167
Changes in Allowance for Loan Losses	The following tables summarize changes in the allowance for loan losses by loan segment for the twelve months ended December 31, 2018, 2017, and 2016: Twelve Months Ended December 31, 2018 Commercial Commercial Real Estate Consumer Residential Finance Total Allowance for loan losses: Balances, December 31, 2017 $ 30,418 $ 27,343 $ 3,732 $ 13,537 $ 2 $ 75,032 Provision for losses 2,097 2,482 679 1,969 7,227 Recoveries on loans 2,456 2,525 302 993 6,276 Loans charged off (2,316 ) (2,741 ) (749 ) (2,177 ) (7,983 ) Balances, December 31, 2018 $ 32,655 $ 29,609 $ 3,964 $ 14,322 $ 2 $ 80,552 Twelve Months Ended December 31, 2017 Commercial Commercial Real Estate Consumer Residential Finance Total Allowance for loan losses: Balances, December 31, 2016 $ 27,696 $ 23,661 $ 2,923 $ 11,755 $ 2 $ 66,037 Provision for losses 2,515 3,159 1,078 2,391 9,143 Recoveries on loans 1,590 2,260 324 706 4,880 Loans charged off (1,383 ) (1,737 ) (593 ) (1,315 ) (5,028 ) Balances, December 31, 2017 $ 30,418 $ 27,343 $ 3,732 $ 13,537 $ 2 $ 75,032 Twelve Months Ended December 31, 2016 Commercial Commercial Real Estate Consumer Residential Finance Total Allowance for loan losses: Balances, December 31, 2015 $ 26,478 $ 22,145 $ 2,689 $ 11,139 $ 2 $ 62,453 Provision for losses 1,876 1,834 432 1,515 5,657 Recoveries on loans 1,806 2,090 369 1,091 5,356 Loans charged off (2,464 ) (2,408 ) (567 ) (1,990 ) (7,429 ) Balances, December 31, 2016 $ 27,696 $ 23,661 $ 2,923 $ 11,755 $ 2 $ 66,037
Allowance for Credit Losses and Loan Portfolio by Loan Segment	The tables below show the Corporation’s allowance for loan losses and loan portfolio by loan segment for the years indicated. At December 31, 2018 and 2017, there was no related allowance for loan losses for loans acquired with deteriorated credit quality. December 31, 2018 Commercial Commercial Consumer Residential Finance Total Allowance balances: Individually evaluated for impairment $ 1,435 $ 1 $ 436 $ 1,872 Collectively evaluated for impairment $ 32,655 28,174 3,963 13,886 $ 2 78,680 Total allowance for loan losses $ 32,655 $ 29,609 $ 3,964 $ 14,322 $ 2 $ 80,552 Loan balances: Individually evaluated for impairment $ 1,838 $ 17,756 $ 18 $ 2,413 $ 22,025 Collectively evaluated for impairment 2,246,730 3,347,686 99,770 1,490,872 $ 1,600 7,186,658 Loans acquired with deteriorated credit quality 2,102 12,389 1,293 15,784 Loans $ 2,250,670 $ 3,377,831 $ 99,788 $ 1,494,578 $ 1,600 $ 7,224,467 December 31, 2017 Commercial Commercial Consumer Residential Finance Total Allowance balances: Individually evaluated for impairment $ 666 $ 567 $ 404 $ 1,637 Collectively evaluated for impairment 29,752 26,776 $ 3,732 13,133 $ 2 73,395 Total allowance for loan losses $ 30,418 $ 27,343 $ 3,732 $ 13,537 $ 2 $ 75,032 Loan balances: Individually evaluated for impairment $ 3,345 $ 17,432 $ 5 $ 2,429 $ 23,211 Collectively evaluated for impairment 2,005,275 3,135,481 86,930 1,472,821 $ 2,527 6,703,034 Loans acquired with deteriorated credit quality 1,421 21,997 1,536 24,954 Loans $ 2,010,041 $ 3,174,910 $ 86,935 $ 1,476,786 $ 2,527 $ 6,751,199
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: December 31, 2018 December 31, 2017 Commercial and industrial loans $ 1,803 $ 3,275 Agriculture production financing and other loans to farmers 679 1,027 Real estate loans: Construction 8,667 65 Commercial and farmland 8,156 12,951 Residential 4,966 9,444 Home equity 1,481 1,928 Individuals' loans for household and other personal expenditures 42 34 Other commercial loans 354 Total $ 26,148 $ 28,724
Composition of Impaired Loans by Loan Class	The following tables show the composition of the Corporation’s impaired loans, related allowance and interest income recognized while impaired by loan class for the years indicated: December 31, 2018 Unpaid Principal Recorded Related Average Recorded Investment Interest Income Recognized Impaired loans with no related allowance: Commercial and industrial loans $ 828 $ 806 $ 833 Agriculture production financing and other loans to farmers 679 679 679 Real estate loans: Construction 1,352 614 835 Commercial and farmland 11,176 8,994 12,975 $ 165 Residential 118 100 101 3 Home equity 49 48 48 Other commercial loans 353 353 353 Total $ 14,555 $ 11,594 $ 15,824 $ 168 Impaired loans with related allowance: Real estate loans: Construction $ 7,978 $ 7,977 $ 1,429 $ 7,977 Commercial and farmland 171 171 6 171 Residential 1,958 1,907 362 1,915 57 Home equity 376 358 74 365 10 Individuals' loans for household and other personal expenditures 18 18 1 20 $ 1 Total $ 10,501 $ 10,431 $ 1,872 $ 10,448 $ 68 Total Impaired Loans $ 25,056 $ 22,025 $ 1,872 $ 26,272 $ 236 December 31, 2017 Unpaid Principal Recorded Related Average Recorded Investment Interest Income Recognized Impaired loans with no related allowance: Commercial and industrial loans $ 7,611 $ 1,536 $ 3,839 Agriculture production financing and other loans to farmers 732 700 762 Real estate loans: Commercial and farmland 16,758 15,163 17,495 $ 360 Residential 833 519 635 Home equity 40 8 14 Individuals' loans for household and other personal expenditures 5 5 7 Total $ 25,979 $ 17,931 $ 22,752 $ 360 Impaired loans with related allowance: Commercial and industrial loans $ 812 $ 782 $ 552 $ 1,517 Agriculture production financing and other loans to farmers 357 327 114 327 Real estate loans: Commercial and farmland 2,988 2,269 567 2,379 Residential 1,616 1,572 327 1,580 $ 28 Home equity 350 330 77 332 11 Total $ 6,123 $ 5,280 $ 1,637 $ 6,135 $ 39 Total Impaired Loans $ 32,102 $ 23,211 $ 1,637 $ 28,887 $ 399 December 31, 2016 Unpaid Principal Recorded Related Average Recorded Investment Interest Income Recognized Impaired loans with no related allowance: Commercial and industrial loans $ 4,028 $ 1,696 $ 1,770 $ 37 Agriculture production financing and other loans to farmers 367 338 357 Real estate loans: Commercial and farmland 22,828 17,752 18,944 288 Residential 2,073 1,402 1,665 2 Home equity 60 30 30 Individuals' loans for household and other personal expenditures 9 9 9 Total $ 29,365 $ 21,227 $ 22,775 $ 327 Impaired loans with related allowance: Agriculture production financing and other loans to farmers $ 660 $ 660 $ 36 $ 690 Real estate loans: Commercial and farmland 4,237 2,985 553 2,990 Residential 968 877 233 872 $ 14 Home equity 290 266 66 266 6 Total $ 6,155 $ 4,788 $ 888 $ 4,818 $ 20 Total Impaired Loans $ 35,520 $ 26,015 $ 888 $ 27,593 $ 347
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-days or more 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 the probability, at acquisition, that all contractually required payments would not be collected are included in the applicable categories below. December 31, 2018 Commercial Pass Commercial Special Mention Commercial Substandard Commercial Doubtful Commercial Loss Consumer Performing Consumer Total Commercial and industrial loans $ 1,660,879 $ 23,246 $ 42,539 $ 1,726,664 Agriculture production financing and other loans to farmers 78,446 5,966 7,992 92,404 Real estate loans: Construction 492,358 2,185 24,224 $ 25,419 $ 1,543 545,729 Commercial and farmland 2,669,491 76,037 84,288 2,285 1 2,832,102 Residential 170,075 7,373 2,076 782,080 4,817 966,421 Home equity 24,653 535 457 500,996 1,516 528,157 Individuals' loans for household and other personal expenditures 99,741 47 99,788 Lease financing receivables, net of unearned income 1,600 1,600 Other commercial loans 431,249 353 431,602 Loans $ 5,528,751 $ 115,342 $ 161,929 $ 1,410,521 $ 7,924 $ 7,224,467 December 31, 2017 Commercial Pass Commercial Special Mention Commercial Substandard Commercial Doubtful Commercial Loss Consumer Performing Consumer Total Commercial and industrial loans $ 1,418,401 $ 51,336 $ 23,386 $ 370 $ 1,493,493 Agriculture production financing and other loans to farmers 73,800 27,502 20,018 387 $ 50 121,757 Real estate loans: Construction 587,906 828 981 $ 22,374 $ 130 612,219 Commercial and farmland 2,408,329 70,074 79,769 1,536 2,980 3 2,562,691 Residential 185,725 4,376 4,209 114 759,900 8,441 962,765 Home equity 28,554 457 286 482,661 2,063 514,021 Individuals' loans for household and other personal expenditures 86,875 60 86,935 Lease financing receivables, net of unearned income 2,527 2,527 Other commercial loans 394,222 569 394,791 Loans $ 5,099,464 $ 154,573 $ 129,218 $ 2,407 $ 50 $ 1,354,790 $ 10,697 $ 6,751,199
Past Due Aging of Loan Portfolio by Loan Class	The tables below show a past due aging of the Corporation’s loan portfolio, by loan class, for the years indicated: December 31, 2018 Current 30-59 Days 60-89 Days Loans 90 Days or More Past Due Non-Accrual Total Past Due Total Commercial and industrial loans $ 1,723,337 $ 1,093 $ 182 $ 249 $ 1,803 $ 3,327 $ 1,726,664 Agriculture production financing and other loans to farmers 89,440 2,285 679 2,964 92,404 Real estate loans: Construction 535,520 64 1,478 8,667 10,209 545,729 Commercial and farmland 2,822,515 1,253 178 8,156 9,587 2,832,102 Residential 959,252 1,756 430 17 4,966 7,169 966,421 Home equity 524,198 2,164 207 107 1,481 3,959 528,157 Individuals' loans for household and other personal expenditures 99,499 179 64 4 42 289 99,788 Lease financing receivables, net of unearned income 1,600 1,600 Other commercial loans 431,248 354 354 431,602 Loans $ 7,186,609 $ 8,794 $ 1,061 $ 1,855 $ 26,148 $ 37,858 $ 7,224,467 December 31, 2017 Current 30-59 Days 60-89 Days Loans 90 Days or More Past Due Non-Accrual Total Past Due Total Commercial and industrial loans $ 1,487,221 $ 2,967 $ 30 $ 3,275 $ 6,272 $ 1,493,493 Agriculture production financing and other loans to farmers 120,720 10 1,027 1,037 121,757 Real estate loans: Construction 610,896 1,193 $ 65 65 1,323 612,219 Commercial and farmland 2,542,048 6,923 166 603 12,951 20,643 2,562,691 Residential 948,947 4,010 308 56 9,444 13,818 962,765 Home equity 510,362 1,372 184 175 1,928 3,659 514,021 Individuals' loans for household and other personal expenditures 85,744 298 834 25 34 1,191 86,935 Lease financing receivables, net of unearned income 2,527 2,527 Other commercial loans 394,791 394,791 Loans $ 6,703,256 $ 16,773 $ 1,522 $ 924 $ 28,724 $ 47,943 $ 6,751,199
Schedules of Troubled Debt Restructuring	The following tables summarize troubled debt restructures in the Corporation's loan portfolio that occurred during the periods ended December 31, 2018 and 2017 : December 31, 2018 Pre-Modification Post-Modification Number Real estate loans: Commercial and farmland $ 85 $ 85 1 Residential 490 487 11 Home equity 81 81 3 Individuals' loans for household and other personal expenditures 65 66 3 Total $ 721 $ 719 18 December 31, 2017 Pre-Modification Post-Modification Number Commercial and industrial loans $ 599 $ 376 3 Agriculture production financing and other loans to farmers 387 387 3 Real estate loans: Commercial and farmland 1,022 1,156 8 Residential 788 862 15 Home equity 195 107 4 Individuals' loans for household and other personal expenditures 13 14 1 Total $ 3,004 $ 2,902 34 The following tables summarize the recorded investment of troubled debt restructures as of December 31, 2018 and 2017 , by modification type, that occurred during the years indicated: December 31, 2018 Term Rate Combination Total Real estate loans: Commercial and farmland $ 85 $ 85 Residential $ 209 $ 239 448 Home equity 106 74 180 Individuals' loans for household and other personal expenditures 58 6 64 Total $ 249 $ 289 $ 239 $ 777 December 31, 2017 Term Rate Combination Total Commercial and industrial loans $ 203 $ 166 $ 369 Agriculture production financing and other loans to farmers 387 387 Real estate loans: Commercial and farmland 705 $ 59 232 996 Residential 761 85 846 Home equity 105 105 Individuals' loans for household and other personal expenditures 14 14 Total $ 1,295 $ 939 $ 483 $ 2,717 The following tables summarize troubled debt restructures that occurred during the twelve months ended December 31, 2018 and 2017 , 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-days or more past due. Twelve Months Ended December 31, 2018 Number of Loans Recorded Balance Real estate loans: Residential 2 $ 75 Total 2 $ 75 Twelve Months Ended December 31, 2017 Number of Loans Recorded Balance Real estate loans: Commercial and farmland 1 $ 14 Residential 4 323 Total 5 $ 337

Accounting for Certain Loans _2

Accounting for Certain Loans Acquired in a Purchase (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Schedule of Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement	The accretable amount, or income expected to be collected, and reclassifications from nonaccretable, are identified in the table below. Twelve Months Ended December 31, 2018 Twelve Months Ended December 31, 2017 Twelve Months Ended December 31, 2016 Beginning balance $ 2,890 $ 3,950 $ 5,612 Additions 1,608 Accretion (4,118 ) (6,749 ) (6,577 ) Reclassification from nonaccretable 3,387 4,748 5,172 Disposals (16 ) (667 ) (257 ) Ending balance $ 2,143 $ 2,890 $ 3,950
Schedule of Loans Acquired for which Contractually Required Payments would not be Collected	Acquired loan data for IAB can be found in the table below: Fair Value of Acquired Loans at Acquisition Date Gross Contractual Amounts Receivable at Acquisition Date Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected Acquired receivables subject to ASC 310-30 $ 4,838 $ 14,131 $ 8,352 Acquired receivables not subject to ASC 310-30 $ 720,544 $ 864,613 $ 9,786 Acquired loan data for Arlington Bank can be found in the table below: Fair Value of Acquired Loans at Acquisition Date Gross Contractual Amounts Receivable at Acquisition Date Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected Acquired receivables subject to ASC 310-30 $ 2,625 $ 6,183 $ 2,891 Acquired receivables not subject to ASC 310-30 $ 222,055 $ 308,857 $ 2,741 The following table presents loans acquired during the period ending December 31, 2017, for which it was probable at acquisition that all contractually required payments would not be collected. There were no loans acquired during the period ending December 31, 2018. 2017 IAB Arlington Bank Total Contractually required payments receivable at acquisition date $ 14,131 $ 6,183 $ 20,314 Nonaccretable difference 8,352 2,891 11,243 Expected cash flows at acquisition date 5,779 3,292 9,071 Accretable difference 941 667 1,608 Basis in loans at acquisition date $ 4,838 $ 2,625 $ 7,463

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule of Premises and Equipment	The following table summarizes the Corporation's premises and equipment as of December 31, 2018 and 2017 : 2018 2017 Cost at December 31: Land $ 21,762 $ 22,042 Buildings and Leasehold Improvements 125,366 124,441 Equipment 86,498 82,344 Total Cost 233,626 228,827 Accumulated Depreciation and Amortization (140,206 ) (132,975 ) Net $ 93,420 $ 95,852
Schedule of Future Minimum Rental Payments for Operating Leases	The future minimum rental commitments required under the operating leases, which expire at various dates through the year 2035, are as follows for the years ending December 31: Future Minimum Rental Commitments 2019 $ 3,721 2020 3,584 2021 3,283 2022 3,150 2023 2,622 After 2023 12,495 Total Future Minimum Obligations $ 28,855

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	2017 Balance, January 1 $ 244,000 Goodwill acquired 201,824 Measurement period adjustment $ (469 ) Balance, December 31 $ 445,355

Other Intangibles (Tables)

Other Intangibles (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Core Deposit and Other Intangibles	The carrying basis and accumulated amortization of recognized core deposit and other intangibles are noted below. 2018 2017 Gross carrying amount $ 85,869 $ 63,940 Core deposit intangible acquired 18,164 Other intangibles acquired 3,765 Accumulated amortization (61,440 ) (54,721 ) Core Deposit and Other Intangibles $ 24,429 $ 31,148
Schedule of Estimated Future Amortization Expense	Estimated future amortization expense is summarized as follows: Amortization Expense 2019 $ 5,169 2020 3,632 2021 3,427 2022 3,325 2023 3,175 After 2023 5,701 $ 24,429

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Schedule of Deposits	The composition of the deposit portfolio is included in the table below for the years indicated: December 31, 2018 December 31, 2017 Demand deposits $ 3,985,178 $ 3,746,654 Savings deposits 2,282,701 1,994,366 Certificates and other time deposits of $100,000 or more 593,592 468,895 Other certificates and time deposits 646,682 581,894 Brokered deposits 246,440 380,721 Total deposits $ 7,754,593 $ 7,172,530
Summary of Contractual Maturities of Time Deposits	At December 31, 2018 , the contractual maturities of time deposits are summarized as follows: Certificates and Other Time Deposits 2019 $ 1,007,653 2020 361,663 2021 70,327 2022 27,535 2023 17,977 After 2023 1,559 $ 1,486,714

Transfers Accounted for as Se_2

Transfers Accounted for as Secured Borrowings (Tables)	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Schedule of Collateral Pledged for all Repurchase Agreements Accounted for as Secured Borrowings	The collateral pledged for all repurchase agreements that are accounted for as secured borrowings as of December 31, 2018 and 2017 were: December 31, 2018 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater Than 90 Days Total U.S. Government-sponsored mortgage-backed securities $ 104,883 1,014 7,615 $ 113,512 December 31, 2017 Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 Days 30-90 Days Greater Than 90 Days Total U.S. Government-sponsored mortgage-backed securities $ 126,187 1,340 1,500 7,596 $ 136,623

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Debt	The following table summarizes the Corporation's borrowings as of December 31, 2018 and 2017: December 31, 2018 December 31, 2017 Federal funds purchased $ 104,000 $ 144,038 Securities sold under repurchase agreements 113,512 136,623 Federal Home Loan Bank advances 314,986 414,377 Subordinated debentures and term loans 138,463 139,349 Total Borrowings $ 670,961 $ 834,387
Schedule of Maturities of Long-term Debt	Contractual maturities of borrowings as of December 31, 2018 , are as follows: Maturities in Years Ending December 31: Federal Funds Purchased Securities Sold Federal Home Subordinated 2019 $ 104,000 $ 113,512 $ 113,713 2020 41,273 2021 55,000 2022 45,000 2023 35,000 After 2023 25,000 $ 142,322 ASC 805 fair value adjustments at acquisition (3,859 ) $ 104,000 $ 113,512 $ 314,986 $ 138,463

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Financial Instruments and Classification 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, 2018 and December 31, 2017 . Asset Derivatives Liability Derivatives December 31, 2018 December 31, 2017 December 31, 2018 December 31, 2017 Balance Sheet Location Fair Balance Sheet Location Fair Balance Sheet Location Fair Balance Sheet Location Fair Derivatives designated as hedging instruments: Interest rate contracts Other Assets $ 135 Other Assets $ 18 Other Liabilities $ 688 Other Liabilities $ 1,383 Derivatives not designated as hedging instruments: Interest rate contracts Other Assets $ 11,948 Other Assets $ 7,305 Other Liabilities $ 11,948 Other Liabilities $ 7,305
Amount of Gain (Loss) Recognized in Other Comprehensive Income	The amount of gain (loss) recognized in other comprehensive income is included in the table below for the periods indicated. Derivatives in Cash Flow Hedging Relationships Amount of Gain (Loss) Recognized in Other Comprehensive Income on Derivative 2018 2017 Interest rate products $ 247 $ 13
Effect of Derivative Financial 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, 2018 , 2017 and 2016 . Derivatives Not Location of Gain Amount of Gain (Loss) Recognized in Income on Derivative 2018 2017 2016 Interest rate contracts Other income $ 211 Derivatives Designated as Hedging Location of Loss Reclassified from Accumulated Other Comprehensive Income (Effective Portion) Amount of Loss Reclassified from Other Comprehensive Income into Income (Effective Portion) 2018 2017 2016 Interest rate contracts Interest expense $ (470 ) $ (985 ) $ (1,250 )

Fair Values of Financial Inst_2

Fair Values of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements of Assets and Liabilities Recognized in the Balance Sheets Measured at Fair Value on Recurring Basis	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, 2018 and 2017 . Fair Value Measurements Using: Quoted Prices in Active Significant Other Observable Inputs Significant December 31, 2018 Fair Value (Level 1) (Level 2) (Level 3) Available for sale securities: U.S. Government-sponsored agency securities $ 13,582 $ 13,582 State and municipal 606,135 602,842 $ 3,293 U.S. Government-sponsored mortgage-backed securities 522,447 522,443 4 Corporate obligations 31 31 Interest rate swap asset 11,948 11,948 Interest rate cap 135 135 Interest rate swap liability 12,636 12,636 Fair Value Measurements Using: Quoted Prices in Active Significant Other Observable Inputs Significant December 31, 2017 Fair Value (Level 1) (Level 2) (Level 3) Available for sale securities: U.S. Government-sponsored agency securities State and municipal $ 526,693 $ 522,750 $ 3,943 U.S. Government-sponsored mortgage-backed securities 470,866 470,866 Corporate obligations 31 31 Equity securities 2,357 2,353 4 Interest rate swap asset 7,305 7,305 Interest rate cap 18 18 Interest rate swap liability 8,688 8,688
Reconciliation of Beginning and Ending Balances of Recurring Fair Value Measurements Recognized in the 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, 2018 and 2017 . Available for Sale Securities For The Year Ended December 31, 2018 December 31, 2017 Beginning Balance $ 3,978 $ 5,169 Included in other comprehensive income (49 ) 26 Principal payments (601 ) (1,217 ) Ending balance $ 3,328 $ 3,978
Description of Valuation Methodologies Used for Instruments Measured at Fair Value on a Non-Recurring Basis and Recognized in the 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, 2018 and 2017 . Fair Value Measurements Using Quoted Prices in Active Significant Other Observable Inputs Significant December 31, 2018 Fair Value (Level 1) (Level 2) (Level 3) Impaired Loans (collateral dependent) $ 11,866 $ 11,866 Other real estate owned $ 657 $ 657 Fair Value Measurements Using Quoted Prices in Active Significant Other Observable Inputs Significant December 31, 2017 Fair Value (Level 1) (Level 2) (Level 3) Impaired Loans (collateral dependent) $ 9,576 $ 9,576 Other real estate owned $ 859 $ 859
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, 2018 and 2017 . December 31, 2018 Fair Value Valuation Technique Unobservable Inputs Range (Weighted-Average) State and municipal securities $ 3,293 Discounted cash flow Maturity Call Date 1 month to 20 years Corporate obligations and U.S. Government-sponsored mortgage backed securities $ 35 Discounted cash flow Risk free rate 3 month LIBOR Impaired loans (collateral dependent) $ 11,866 Collateral based measurements Discount to reflect current market conditions and ultimate collectability 0% - 10% (6%) Other real estate owned $ 657 Appraisals Discount to reflect current market conditions 0% - 10% (4%) December 31, 2017 Fair Value Valuation Technique Unobservable Inputs Range (Weighted-Average) State and municipal securities $ 3,943 Discounted cash flow Maturity Call Date 1 month to 20 years Corporate obligations and U.S. Government-sponsored mortgage backed securities $ 35 Discounted cash flow Risk free rate 3 month LIBOR Impaired loans (collateral dependent) $ 9,576 Collateral based measurements Discount to reflect current market conditions and ultimate collectability 0% - 10% (1%) Other real estate owned $ 859 Appraisals Discount to reflect current market conditions 0% - 10% (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, 2018 and 2017 . 2018 Carrying Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Assets at December 31: Cash and cash equivalents $ 139,247 $ 139,247 Interest-bearing time deposits 36,963 36,963 Investment securities available for sale 1,142,195 $ 1,138,867 $ 3,328 Investment securities held to maturity 490,387 481,377 7,840 Loans held for sale 4,778 4,778 Loans 7,143,915 7,004,193 Federal Home Loan Bank stock 24,588 24,588 Interest rate swap asset 12,083 12,083 Interest receivable 40,881 40,881 Liabilities at December 31: Deposits $ 7,754,593 $ 6,267,879 $ 1,464,129 Borrowings: Federal funds purchased 104,000 104,000 Securities sold under repurchase agreements 113,512 113,437 Federal Home Loan Bank advances 314,986 318,728 Subordinated debentures and term loans 138,463 127,298 Interest rate swap liability 12,636 12,636 Interest payable 5,607 5,607 2017 Carrying Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Assets at December 31: Cash and cash equivalents $ 154,905 $ 154,905 Interest-bearing time deposits 35,027 35,027 Investment securities available for sale 999,947 $ 995,969 $ 3,978 Investment securities held to maturity 560,655 556,305 11,903 Loans held for sale 7,216 7,216 Loans 6,676,167 6,534,877 Federal Home Loan Bank stock 23,825 23,825 Interest rate swap asset 7,323 7,323 Interest receivable 37,130 37,130 Liabilities at December 31: Deposits $ 7,172,530 $ 5,741,019 $ 1,406,526 Borrowings: Federal funds purchased 144,038 144,038 Securities sold under repurchase agreements 136,623 136,562 Federal Home Loan Bank advances 414,377 361,085 Subordinated debentures and term loans 139,349 120,085 Interest rate swap liability 8,688 8,688 Interest payable 4,390 4,390

Commitments and Contingent Li_2

Commitments and Contingent Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Financial Instruments which Contract Amount Represents Credit Risk	Financial instruments, whose contract amount represents credit risk as of December 31, were as follows: 2018 2017 Amounts of commitments: Loan commitments to extend credit $ 2,684,806 $ 2,482,641 Standby letters of credit $ 32,862 $ 43,526

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 : Accumulated Other Comprehensive Income (Loss) Unrealized Gains (Losses) on Securities Available for Sale Unrealized Gains (Losses) on Cash Flow Hedges Unrealized Gains (Losses) on Defined Benefit Plans Total Balance at December 31, 2017 $ 8,970 $ (1,125 ) $ (10,753 ) $ (2,908 ) Other comprehensive income before reclassifications (13,872 ) 437 (1,435 ) (14,870 ) Amounts reclassified from accumulated other comprehensive income (3,373 ) 371 (16 ) (3,018 ) Period change (17,245 ) 808 (1,451 ) (17,888 ) Reclassification adjustment under ASU 2018-02 1,932 (242 ) (2,316 ) (626 ) Balance at December 31, 2018 $ (6,343 ) $ (559 ) $ (14,520 ) $ (21,422 ) Balance at December 31, 2016 $ 1,035 $ (1,774 ) $ (12,842 ) $ (13,581 ) Other comprehensive income before reclassifications 9,645 9 2,686 12,340 Amounts reclassified from accumulated other comprehensive income (1,710 ) 640 (597 ) (1,667 ) Period change 7,935 649 2,089 10,673 Balance at December 31, 2017 $ 8,970 $ (1,125 ) $ (10,753 ) $ (2,908 )
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 years ended December 31, 2018 , 2017 and 2016 : Amount Reclassified from Accumulated Other Comprehensive Income (Loss) For the Year Ended December 31, Details about Accumulated Other Comprehensive Income (Loss) Components 2018 2017 2016 Affected Line Item in the Statements of Income Unrealized gains (losses) on available for sale securities (1) Realized securities gains reclassified into income $ 4,269 $ 2,631 $ 3,389 Other income - net realized gains on sales of available for sale securities Related income tax expense (896 ) (921 ) (1,186 ) Income tax expense $ 3,373 $ 1,710 $ 2,203 Unrealized gains (losses) on cash flow hedges (2) Interest rate contracts $ (470 ) $ (985 ) $ (1,250 ) Interest expense - subordinated debentures and term loans Related income tax benefit 99 345 437 Income tax expense $ (371 ) $ (640 ) $ (813 ) Unrealized gains (losses) on defined benefit plans Amortization of net loss and prior service costs $ 20 $ 806 $ 1,588 Other expenses - salaries and employee benefits Related income tax benefit (expense) (4 ) (209 ) (556 ) Income tax expense $ 16 $ 597 $ 1,032 Total reclassifications for the period, net of tax $ 3,018 $ 1,667 2,422 (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 4. 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 and Divide_2

Regulatory Capital and Dividends (Tables)	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Schedule of Actual and Required Capital Amounts and Ratios	The Corporation's and Bank's actual and required capital ratios as of December 31, 2018 and December 31, 2017 were as follows: Prompt Corrective Action Thresholds Actual Adequately Capitalized Well Capitalized December 31, 2018 Amount Ratio Amount Ratio Amount Ratio Total risk-based capital to risk-weighted assets First Merchants Corporation $ 1,177,725 14.61 % $ 644,871 8.00 % N/A N/A First Merchants Bank 1,092,602 13.46 649,531 8.00 $ 811,914 10.00 % Tier 1 capital to risk-weighted assets First Merchants Corporation $ 1,032,173 12.80 % $ 483,653 6.00 % N/A N/A First Merchants Bank 1,012,050 12.47 487,148 6.00 $ 649,531 8.00 % Common equity tier 1 capital to risk-weighted assets First Merchants Corporation $ 966,032 11.98 % $ 362,740 4.50 % N/A N/A First Merchants Bank 1,012,050 12.47 365,361 4.50 $ 527,744 6.50 % Tier 1 capital to average assets First Merchants Corporation $ 1,032,173 10.91 % $ 378,379 4.00 % N/A N/A First Merchants Bank 1,012,050 10.70 378,397 4.00 $ 472,996 5.00 % Prompt Corrective Action Thresholds Actual Adequately Capitalized Well Capitalized December 31, 2017 Amount Ratio Amount Ratio Amount Ratio Total risk-based capital to risk-weighted assets First Merchants Corporation $ 1,048,757 13.69 % $ 612,848 8.00 % N/A N/A First Merchants Bank 1,016,355 13.17 617,477 8.00 $ 771,847 10.00 % Tier 1 capital to risk-weighted assets First Merchants Corporation $ 908,725 11.86 % $ 459,636 6.00 % N/A N/A First Merchants Bank 941,323 12.20 463,108 6.00 $ 617,477 8.00 % Common equity tier 1 capital to risk-weighted assets First Merchants Corporation $ 842,806 11.00 % $ 344,727 4.50 % N/A N/A First Merchants Bank 941,323 12.20 347,331 4.50 $ 501,700 6.50 % Tier 1 capital to average assets First Merchants Corporation $ 908,725 10.43 % $ 348,407 4.00 % N/A N/A First Merchants Bank 941,323 10.83 347,794 4.00 $ 434,742 5.00 %

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Components of Share Based Compensation Awards	The following table summarizes the components of the Corporation's share-based compensation awards recorded as an expense and the income tax benefit of such awards. The income tax benefit decrease for the year ended December 31, 2018 was due to the reduction of the corporate federal income tax rate from 35 percent to 21 percent as a result of the Tax Cuts and Jobs Act, which was effective January 1, 2018. The income tax benefit increase for the year ended December 31, 2017 was due to the implementation of ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . This ASU requires all income tax effects of awards to be recognized as income tax expense or benefit in the income statement when the awards vest or are settled. Implementation of the ASU was effective January 1, 2017 and resulted in approximately $644,000 and $935,000 of income tax benefit for the years ended December 31, 2018 and 2017, respectively. Years Ended December 31, 2018 2017 2016 Stock and ESPP Options Pre-tax compensation expense $ 109 $ 121 $ 76 Income tax expense (benefit) (97 ) (322 ) 18 Stock and ESPP option expense, net of income taxes $ 12 $ (201 ) $ 94 Restricted Stock Awards Pre-tax compensation expense $ 3,483 $ 2,706 $ 2,524 Income tax benefit (1,179 ) (1,561 ) (883 ) Restricted stock awards expense, net of income taxes $ 2,304 $ 1,145 $ 1,641 Total Share-Based Compensation: Pre-tax compensation expense $ 3,592 $ 2,827 $ 2,600 Income tax benefit (1,276 ) (1,883 ) (865 ) Total share-based compensation expense, net of income taxes $ 2,316 $ 944 $ 1,735
Stock Option Activity Under Stock Option Plans	Stock option activity under the Corporation's stock option plans, as of December 31, 2018 , and changes during the year ended December 31, 2018 , were as follows: Number of Weighted-Average Price Weighted Average Aggregate Outstanding at January 1, 2018 152,652 $ 16.71 Exercised (76,152 ) $ 20.99 Canceled (200 ) $ 28.25 Outstanding December 31, 2018 76,300 $ 12.40 2.86 $ 1,668,871 Vested and Expected to Vest at December 31, 2018 76,300 $ 12.40 2.86 $ 1,668,871 Exercisable at December 31, 2018 76,300 $ 12.40 2.86 $ 1,668,871
Summary of Unvested RSAs Outstanding	The following table summarizes information on unvested RSAs outstanding as of December 31, 2018 : Number of Weighted-Average Unvested RSAs at January 1, 2018 366,993 $ 29.79 Granted 105,100 $ 48.11 Forfeited (15,198 ) $ 42.00 Vested (112,533 ) $ 23.84 Unvested RSAs at December 31, 2018 344,362 $ 36.80

Pension and Other Post Retire_2

Pension and Other Post Retirement Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Schedule of Plans' Funded Status and Amounts Recognized in the Balance Sheets	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, 2018 and 2017 . 2018 2017 Change in Benefit Obligation: Benefit obligation at beginning of year $ 82,157 $ 84,090 Service cost 8 10 Interest cost 2,816 3,353 Actuarial (gain) loss (6,129 ) 3,686 Benefits paid (5,659 ) (5,179 ) Plan settlements (3,803 ) Benefit obligation at end of year $ 73,193 $ 82,157 Change in Plan Assets: Fair value of plan assets at beginning of year $ 85,213 $ 83,557 Actual return on plan assets (3,427 ) 9,968 Employer contributions 609 670 Benefits paid (5,659 ) (5,179 ) Plan settlements (3,803 ) End of year 76,736 85,213 Funded status at end of year $ 3,543 $ 3,056 Assets and Liabilities Recognized in the Balance Sheets: Deferred tax asset $ 3,855 $ 3,474 Assets $ 7,024 $ 7,660 Liabilities $ 3,481 $ 4,604 Amounts Recognized in Accumulated Other Comprehensive Income Not Yet Recognized as Components of Net Periodic Cost, net of tax, consist of: Accumulated loss $ (14,111 ) $ (10,360 ) Prior service cost (409 ) (393 ) $ (14,520 ) $ (10,753 )
Schedule of Accumulated Benefit Obligation in Excess of Plan Assets	Information for pension plans with an accumulated benefit obligation in excess of plan assets consists solely of the non-qualified plans for certain employees, former employees and former non-employee directors, and is included in the table below. December 31, 2018 December 31, 2017 Projected benefit obligation $ 3,481 $ 4,604 Accumulated benefit obligation $ 3,481 $ 4,604 Fair value of plan assets $ — $ —
Schedule of Net Periodic Pension Costs	The following table shows the components of net periodic pension benefit cost: December 31, 2018 December 31, 2017 December 31, 2016 Service cost $ 8 $ 10 $ 9 Interest cost 2,816 3,353 3,273 Expected return on plan assets (4,891 ) (4,778 ) (4,508 ) Amortization of prior service cost 87 90 79 Amortization of net loss 287 1,218 1,656 Settlement loss recognized 761 Net periodic pension benefit cost $ (1,693 ) $ 654 $ 509
Schedule of Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss)	Other changes in plan assets and benefit obligations recognized in other comprehensive income: December 31, 2018 December 31, 2017 December 31, 2016 Net periodic pension benefit cost $ (1,693 ) $ 654 $ 509 Net gain (loss) (2,189 ) 1,504 (228 ) Amortization of net loss 287 1,979 1,656 Amortization of prior service cost 87 90 79 Total recognized in other comprehensive income (loss) (1,815 ) 3,573 1,507 Total recognized in net periodic pension benefit cost and other comprehensive income (loss) $ (122 ) $ 2,919 $ 998
Schedule of Amounts in Accumulated Other Comprehensive Income to be Recognized over Next Fiscal Year	The estimated amounts that will be amortized from accumulated other comprehensive income into net periodic pension benefit cost over the next fiscal year are: December 31, 2018 December 31, 2017 December 31, 2016 Amortization of net loss $ (432 ) $ (830 ) $ (1,208 ) Amortization of prior service cost (87 ) (87 ) (90 ) Total $ (519 ) $ (917 ) $ (1,298 )
Schedule of Assumptions Used	Significant assumptions include: December 31, 2018 December 31, 2017 December 31, 2016 Weighted-average Assumptions Used to Determine Benefit Obligation: Discount rate 4.30 % 3.60 % 4.20 % Rate of compensation increase for accruing active participants n/a n/a 3.00 % Weighted-average Assumptions Used to Determine Cost: Discount rate 3.60 % 4.20 % 4.50 % Expected return on plan assets 6.00 % 6.00 % 6.00 % Rate of compensation increase for accruing active participants n/a n/a 3.00 %
Schedule of Expected Benefit Payments	The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid as of December 31, 2018 . The minimum contribution required in 2019 will likely be zero , but the Corporation may decide to make a discretionary contribution during the year. 2019 $ 5,583 2020 5,549 2021 5,429 2022 5,363 2023 5,269 After 2023 24,586 $ 51,779
Schedule of Allocation of 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 $71,277,000 and $78,280,000 as of December 31, 2018 and 2017 , respectively, 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 $5,459,000 and $6,933,000 as of December 31, 2018 and 2017 , respectively, and include governmental agencies, taxable municipal bonds and notes, 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, 2018 and 2017 . Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs December 31, 2018 Fair Value (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 3,026 $ 3,026 Corporate Bonds and Notes 16,691 16,691 Government Agency and Municipal Bonds and Notes 4,479 $ 4,479 Certificates of Deposit 980 980 Party-in-Interest Investments Common Stock 2,073 2,073 Mutual Funds Taxable Bond 12,817 12,817 Large Cap Equity 18,269 18,269 Mid Cap Equity 8,735 8,735 Small Cap Equity 4,713 4,713 International Equity 3,336 3,336 Specialty Alternative Equity 1,617 1,617 $ 76,736 $ 71,277 $ 5,459 Fair Value Measurements Using Quoted Prices in Significant Other Observable Inputs Significant December 31, 2017 Fair Value (Level 1) (Level 2) (Level 3) Cash & Cash Equivalents $ 5,123 $ 5,123 Corporate Bonds and Notes 14,598 14,598 Government Agency and Municipal Bonds and Notes 5,679 $ 5,679 Certificates of Deposit 1,254 1,254 Party-in-Interest Investments Common Stock 2,545 2,545 Mutual Funds Taxable Bond 12,198 12,198 Large Cap Equity 22,137 22,137 Mid Cap Equity 10,676 10,676 Small Cap Equity 5,264 5,264 International Equity 4,030 4,030 Specialty Alternative Equity 1,709 1,709 $ 85,213 $ 78,280 $ 6,933 Plan assets are re-balanced quarterly. At December 31, 2018 and 2017 , plan assets by category are as follows: December 31, 2018 December 31, 2017 Actual Target Actual Target Cash and cash equivalents 3.9 % 3.0 % 6.0 % 3.0 % Equity securities 48.4 50.0 52.4 55.0 Debt securities 45.6 45.0 39.6 40.0 Alternative investments 2.1 2.0 2.0 2.0 100.0 % 100.0 % 100.0 % 100.0 %

Income Tax (Tables)

Income Tax (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Reconciliation of Federal Statutory to Actual Tax Expense	The reconciliation between income tax expense expected at the U.S. federal statutory tax rate and the reported income tax expense is summarized in the following table for years ended December 31, 2018 , 2017 , 2016 : 2018 2017 2016 Reconciliation of Federal Statutory to Actual Tax Expense: Federal Statutory Income Tax at 21% for 2018 and 35% for 2017 and 2016 $ 39,509 $ 46,758 $ 38,031 Tax-exempt Interest Income (8,347 ) (11,127 ) (8,749 ) Stock Compensation (622 ) (893 ) (61 ) Earnings on Life Insurance (868 ) (2,302 ) (1,486 ) Tax Credits (615 ) (811 ) (564 ) Tax Cuts and Jobs Act - Rate Reform Impact 5,120 Other (58 ) 779 438 Income Tax Expense $ 28,999 $ 37,524 $ 27,609 Effective Tax Rate 15.4 % 28.1 % 25.4 %
Components of Income Tax Expense (Benefit)	Income tax expense consists of the following components for the years ended December 31, 2018 , 2017 , 2016 : 2018 2017 2016 Income Tax Expense for the Year Ended December 31: Currently Payable: Federal 23,633 $ 22,001 $ 18,998 State 1,842 Deferred: Federal 6,723 9,969 8,233 Tax Cuts and Jobs Act - Rate Reform Impact 5,120 State (3,199 ) 434 378 Income Tax Expense $ 28,999 $ 37,524 $ 27,609
Deferred Tax Assets and Liabilities	Significant components of the net deferred tax assets (liabilities) resulting from temporary differences were as follows at December 31, 2018 and 2017 : 2018 2017 Deferred Tax Asset at December 31: Assets: Differences in Accounting for Loan Losses $ 19,785 $ 19,526 Differences in Accounting for Loan Fees 749 1,458 Differences in Accounting for Loans and Securities 710 3,681 Deferred Compensation 2,101 4,448 Federal & State Income Tax Loss Carryforward and Credits 6,954 10,829 Net Unrealized Loss on Securities Available for Sale 1,686 Other 2,028 365 Total Assets 34,013 40,307 Liabilities: Differences in Depreciation Methods 6,496 5,245 Difference in Accounting for Pensions and Other Employee Benefits 566 823 State Income Tax 791 58 Net Unrealized Gain on Securities Available for Sale 2,898 Gain on FDIC Modified Whole Bank Transaction 487 602 Other 4,271 3,897 Total Liabilities 12,611 13,523 Net Deferred Tax Asset Before Valuation Allowance 21,402 26,784 Valuation allowance: Beginning Balance (6,966 ) (9,815 ) Decrease/(Increase) During the Year 6,966 2,849 Ending Balance — (6,966 ) Net Deferred Tax Asset $ 21,402 $ 19,818

Net Income Per Share (Tables)

Net Income Per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Reconciliation of Basic and Diluted Net Income Per Share	The following table reconciles basic and diluted net income per share for the years indicated: 2018 2017 2016 Weighted-Average Shares Weighted-Average Shares Weighted-Average Shares Basic net income per share: Net income available to common stockholders $ 159,139 49,262,015 $ 3.23 $ 96,070 45,181,221 $ 2.13 $ 81,051 40,767,343 $ 1.99 Effect of dilutive stock options and restricted stock awards 208,908 221,757 245,790 Diluted net income per share: Net income available to common stockholders $ 159,139 49,470,923 $ 3.22 $ 96,070 45,402,978 $ 2.12 $ 81,051 41,013,133 $ 1.98

Quarterly Results of Operatio_2

Quarterly Results of Operations (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Results of Operations (Unaudited)	The following table sets forth certain quarterly results for the years ended December 31, 2018 and 2017 : 2018 2017 First Second Third Fourth First Second Third Fourth Interest income $ 93,620 $ 100,871 $ 104,800 $ 108,653 $ 68,234 $ 71,467 $ 84,847 $ 90,348 Interest expense 13,704 16,300 18,314 20,769 7,235 8,367 10,427 11,583 Net interest income 79,916 84,571 86,486 87,884 60,999 63,100 74,420 78,765 Provision for loan losses 2,500 1,663 1,400 1,664 2,385 2,875 2,083 1,800 Net interest income after provision for loan losses 77,416 82,908 85,086 86,220 58,614 60,225 72,337 76,965 Non-interest income 19,561 18,191 19,527 19,180 14,846 18,434 18,668 19,061 Non-interest expense 53,687 53,504 55,022 57,738 43,099 47,316 58,708 56,433 Income before income tax expense 43,290 47,595 49,591 47,662 30,361 31,343 32,297 39,593 Income tax expense 6,611 7,961 8,478 5,949 7,168 7,207 7,939 15,210 Net income available to common stockholders $ 36,679 $ 39,634 $ 41,113 $ 41,713 $ 23,193 $ 24,136 $ 24,358 $ 24,383 Basic EPS $ 0.75 $ 0.80 $ 0.83 $ 0.85 $ 0.57 $ 0.57 $ 0.50 $ 0.49 Diluted EPS $ 0.74 $ 0.80 $ 0.83 $ 0.85 $ 0.56 $ 0.57 $ 0.50 $ 0.49 Average Shares Outstanding: Basic 49,192,647 49,252,580 49,286,945 49,314,276 40,984,481 42,038,824 48,431,880 49,144,310 Diluted 49,427,972 49,451,406 49,492,019 49,511,233 41,220,586 42,243,539 48,643,774 49,379,303

Condensed Financial Informati_2

Condensed Financial Information (parent company only) (Tables)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Schedule of Parent Company Information, Condensed Balance Sheets	Condensed Balance Sheets December 31, 2018 December 31, 2017 Assets Cash $ 87,435 $ 31,527 Investment in subsidiaries 1,459,036 1,411,360 Investment securities 31 Premises and equipment 1,158 1,252 Interest receivable 6 5 Goodwill 448 448 Cash surrender value of life insurance 810 787 Other assets 5,240 3,480 Total assets $ 1,554,133 $ 1,448,890 Liabilities Subordinated debentures and term loans $ 138,463 $ 138,241 Interest payable 994 968 Other liabilities 6,416 6,218 Total liabilities 145,873 145,427 Stockholders' equity 1,408,260 1,303,463 Total liabilities and stockholders' equity $ 1,554,133 $ 1,448,890
Schedule of Parent Company Information, Condensed Statements of Income and Comprehensive Income	Condensed Statements of Income and Comprehensive Income December 31, 2018 December 31, 2017 December 31, 2016 Income Dividends from subsidiaries $ 100,954 $ 33,014 $ 33,546 Loss on sale of available for sale securities (50 ) Other income 572 350 143 Total income 101,526 33,314 33,689 Expenses Interest expense 8,233 7,572 7,185 Salaries and employee benefits 3,729 4,118 639 Net occupancy and equipment expenses 851 797 832 Other outside services 489 1,810 967 Professional services 270 442 279 Other expenses 442 (385 ) (470 ) Total expenses 14,014 14,354 9,432 Income before income tax benefit and equity in undistributed income of subsidiaries 87,512 18,960 24,257 Income tax benefit 3,298 5,946 3,243 Income before equity in undistributed income of subsidiaries 90,810 24,906 27,500 Equity in undistributed income of subsidiaries 68,329 71,164 53,551 Net income available to common stockholders $ 159,139 $ 96,070 $ 81,051 Net income $ 159,139 $ 96,070 $ 81,051 Other comprehensive income (loss) (17,888 ) 10,673 (12,219 ) Comprehensive income $ 141,251 $ 106,743 $ 68,832
Schedule of Parent Company Information, Condensed Statement of Cash Flows	Condensed Statement of Cash Flows December 31, 2018 December 31, 2017 December 31, 2016 Cash Flow From Operating Activities: Net income $ 159,139 $ 96,070 $ 81,051 Adjustments to Reconcile Net Income to Net Cash: Share-based compensation 1,256 1,215 1,166 Distributions in excess of (equity in undistributed) income of subsidiaries (68,329 ) (71,164 ) (53,551 ) Loss on sale of available for sale securities 50 Net Change in: Other assets 584 3,358 833 Other liabilities 274 (1,900 ) 849 Investment in subsidiaries - operating activities 841 1,112 (1,938 ) Net cash provided by operating activities 93,765 28,741 28,410 Cash Flow From Investing Activities: Purchase of securities available for sale (19,804 ) Net cash received in acquisition 37 Other 2,189 Net cash provided (used) in investing activities 2,189 37 (19,804 ) Cash Flow From Financing Activities: Cash dividends (41,660 ) (31,820 ) (22,203 ) Stock issued under employee benefit plans 707 519 462 Stock issued under dividend reinvestment and stock purchase plan 1,211 991 835 Stock options exercised 1,598 2,398 2,602 Stock redeemed (1,902 ) (1,283 ) (1,980 ) Net cash used by financing activities (40,046 ) (29,195 ) (20,284 ) Cash, beginning of the year 31,527 31,944 43,622 Cash, end of year $ 87,435 $ 31,527 $ 31,944

Nature of Operations and Summ_3

Nature of Operations and Summary of Significant Accounting Policies - Allowance for Loan Losses (Details)	12 Months Ended
	Dec. 31, 2018USD ($)key_element
Accounting Policies [Abstract]
Number of key element used in assessing the appropriateness of the allowance for loan losses | key_element	3
Commercial relationships threshold that exhibit credit weaknesses | $	$ 500,000

Nature of Operations and Summ_4

Nature of Operations and Summary of Significant Accounting Policies - Premises and Equipment (Details)	12 Months Ended
	Dec. 31, 2018
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 Summ_5

Nature of Operations and Summary of Significant Accounting Policies - Intangible Assets (Details)	12 Months Ended
	Dec. 31, 2018
Minimum
Intangible Assets [Abstract]
Estimated useful lives of intangible assets	2 years
Maximum
Intangible Assets [Abstract]
Estimated useful lives of intangible assets	20 years

Nature of Operations and Summ_6

Nature of Operations and Summary of Significant Accounting Policies - Requisite Service Period, Stock Award Plans (Details)	12 Months Ended
	Dec. 31, 2018
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

Nature of Operations and Summ_7

Nature of Operations and Summary of Significant Accounting Policies - Recent Accounting Changes (Details) - ASU 2017-12 - State and municipal securities	9 Months Ended
	Sep. 30, 2018USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassificaton of investment securities held to maturity	$ (30,800,000)
Reclassification of held to maturity, gross unrealized gains	$ (450,000)

Acquisitions - Acquisitions Nar

Acquisitions - Acquisitions Narrative (Details) $ / shares in Units, $ in Thousands	Jul. 14, 2017USD ($)bank_branchshares	May 19, 2017USD ($)bank_branchshares	Nov. 21, 2016USD ($)$ / sharesshares	Sep. 30, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)	Oct. 09, 2018$ / shares
Business Acquisition [Line Items]
Purchase price per share (in dollars per share) | $ / shares								$ 45.71
Issuance of common stock related to acquisition						$ 321,431
Common Stock
Business Acquisition [Line Items]
Stock issued as a part of acquisition (in shares) | shares						8,044,446
Issuance of common stock related to acquisition						$ 1,006
IAB
Business Acquisition [Line Items]
Shares purchased (in shares) | shares			495,112
Percentage of interest acquired			12.10%	1210.00%
Value of acquired shares			$ 19,800
Purchase price per share (in dollars per share) | $ / shares			$ 40
Number of banking centers acquired | bank_branch	16
Stock issued as a part of acquisition (in shares) | shares	6,000,000
Issuance of common stock related to acquisition	$ 238,800
Total purchase price	258,600
Fair value of equity interest after adjustment				$ 19,800
Remeasurement loss						50
Other intangible assets	17,403
Operating revenue						21,400
IAB | Core deposits
Business Acquisition [Line Items]
Other intangible assets	$ 13,638
Acquired intangible asset, expected useful life	10 years
IAB | Noncompete agreements
Business Acquisition [Line Items]
Other intangible assets	$ 3,765
Acquired intangible asset, expected useful life	2 years
IAB | Common Stock
Business Acquisition [Line Items]
Number of shares of common stock	1.653
Arlington Bank
Business Acquisition [Line Items]
Percentage of interest acquired		100.00%
Number of banking centers acquired | bank_branch		3
Stock issued as a part of acquisition (in shares) | shares		2,100,000
Issuance of common stock related to acquisition		$ 82,600
Other intangible assets		4,526
Operating revenue						9,000
Arlington Bank | Core deposits
Business Acquisition [Line Items]
Other intangible assets		$ 4,526
Acquired intangible asset, expected useful life		10 years
Arlington Bank | Common Stock
Business Acquisition [Line Items]
Number of shares of common stock		2.7245
Arlington Bank and IAB | Expenses directly attributable to acquisitions
Business Acquisition [Line Items]
Non-recurring expenses						$ 15,400

Acquisitions - Assets Acquired

Acquisitions - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Jul. 14, 2017	May 19, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 445,355	$ 445,355			$ 244,000
IAB
Business Acquisition [Line Items]
Cash and cash equivalents			$ 6,016
Interest-bearing time deposits			248,212
Investment securities			4,078
Loans held for sale			594
Loans			725,382
Premises and equipment			10,107
Federal Home Loan Bank stock			4,810
Interest receivable			3,445
Cash surrender value of life insurance			26,964
Other assets			11,780
Deposits			(862,271)
Securities sold under repurchase agreements			(17,915)
Federal Home Loan Bank Advances			(47,575)
Subordinated debentures			(10,583)
Interest payable			(1,005)
Other liabilities			(14,472)
Net tangible assets acquired			87,567
Core deposit intangible			17,403
Goodwill			153,636
Purchase price			$ 258,606
Arlington Bank
Business Acquisition [Line Items]
Cash and cash equivalents				$ 48,532
Interest-bearing time deposits				292
Loans held for sale				7,626
Loans				224,680
Premises and equipment				1,986
Federal Home Loan Bank stock				1,091
Interest receivable				653
Other assets				1,620
Deposits				(252,783)
Interest payable				(244)
Other liabilities				(3,106)
Net tangible assets acquired				30,347
Core deposit intangible				4,526
Goodwill				47,719
Purchase price				$ 82,592

Acquisitions - Schedule of Acqu

Acquisitions - Schedule of Acquired Loan Data (Details) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Jul. 14, 2017	May 19, 2017
Business Acquisition [Line Items]
Fair Value of Acquired Loans at Acquisition Date, subject to ASC 310-30	$ 7,463
Gross Contractual Amounts Receivable at Acquisition Date, subject to ASC 310-30	20,314
IAB
Business Acquisition [Line Items]
Fair Value of Acquired Loans at Acquisition Date, subject to ASC 310-30	4,838	$ 4,838
Gross Contractual Amounts Receivable at Acquisition Date, subject to ASC 310-30	14,131	14,131
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected, subject to ASC 310-30		8,352
Fair Value of Acquired Loans at Acquisition Date, not subject to ASC 310-30		720,544
Gross Contractual Amounts Receivable at Acquisition Date, not subject to ASC 310-30		864,613
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected, not subject to ASC 310-30		$ 9,786
Arlington Bank
Business Acquisition [Line Items]
Fair Value of Acquired Loans at Acquisition Date, subject to ASC 310-30	2,625		$ 2,625
Gross Contractual Amounts Receivable at Acquisition Date, subject to ASC 310-30	$ 6,183		6,183
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected, subject to ASC 310-30			2,891
Fair Value of Acquired Loans at Acquisition Date, not subject to ASC 310-30			222,055
Gross Contractual Amounts Receivable at Acquisition Date, not subject to ASC 310-30			308,857
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected, not subject to ASC 310-30			$ 2,741

Acquisitions - Pro Forma Inform

Acquisitions - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Combinations [Abstract]
Total revenue (net interest income plus other income)	$ 380,324	$ 353,732
Net income available to common shareholders	$ 95,009	$ 95,288
Earnings per share:
Basic (in dollars per share)	$ 1.94	$ 1.95
Diluted (in dollars per share)	$ 1.93	$ 1.94

Cash and Cash Equivalents (Deta

Cash and Cash Equivalents (Details) $ in Thousands	Dec. 31, 2018USD ($)
Restricted Cash and Cash Equivalents Items [Line Items]
Cash balance, Federal Home Loan Bank And Federal Reserve Bank	$ 7,639
Cash reserve with Federal Reserve Bank	45,352
Interest-bearing Deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Cash amount that exceeded federally insured limits	$ 122,092

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Approximate Fair Values of Securities (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Total available for sale
Total Investment Securities	$ 1,149,727,000	$ 986,565,000
Gross Unrealized Gains	6,721,000	17,896,000
Gross Unrealized Losses	14,253,000	4,514,000
Investment securities available for sale	1,142,195,000	999,947,000
Total held to maturity
Amortized Cost	490,387,000	560,655,000
Gross Unrealized Gains	3,571,000	9,636,000
Gross Unrealized Losses	4,741,000	2,083,000
Fair Value	489,217,000	568,208,000
Total Investment Securities
Amortized Cost	1,640,114,000	1,547,220,000
Gross Unrealized Gains	10,292,000	27,532,000
Gross Unrealized Losses	18,994,000	6,597,000
Fair Value	1,631,412,000	1,568,155,000
U.S. Government-sponsored agency securities
Total available for sale
Total Investment Securities	13,493,000
Gross Unrealized Gains	92,000
Gross Unrealized Losses	3,000
Investment securities available for sale	13,582,000
Total held to maturity
Amortized Cost	22,618,000	22,618,000
Gross Unrealized Gains
Gross Unrealized Losses	545,000	435,000
Fair Value	22,073,000	22,183,000
State and municipal
Total available for sale
Total Investment Securities	605,994,000	510,852,000
Gross Unrealized Gains	5,995,000	16,932,000
Gross Unrealized Losses	5,854,000	1,091,000
Investment securities available for sale	606,135,000	526,693,000
Total held to maturity
Amortized Cost	197,909,000	235,594,000
Gross Unrealized Gains	2,858,000	6,295,000
Gross Unrealized Losses	872,000	244,000
Fair Value	199,895,000	241,645,000
U.S. Government-sponsored mortgage-backed securities
Total available for sale
Total Investment Securities	530,209,000	473,325,000
Gross Unrealized Gains	634,000	964,000
Gross Unrealized Losses	8,396,000	3,423,000
Investment securities available for sale	522,447,000	470,866,000
Total held to maturity
Amortized Cost	268,860,000	301,443,000
Gross Unrealized Gains	713,000	3,341,000
Gross Unrealized Losses	3,323,000	1,404,000
Fair Value	266,250,000	303,380,000
Corporate obligations
Total available for sale
Total Investment Securities	31,000	31,000
Gross Unrealized Gains
Gross Unrealized Losses
Investment securities available for sale	31,000	31,000
Foreign Investment
Total available for sale
Gross Unrealized Losses	0
Total held to maturity
Amortized Cost	1,000,000	1,000,000
Gross Unrealized Gains
Gross Unrealized Losses	1,000
Fair Value	$ 999,000	1,000,000
Equity securities
Total available for sale
Total Investment Securities		2,357,000
Gross Unrealized Gains
Gross Unrealized Losses
Investment securities available for sale		$ 2,357,000

Investment Securities - Narrati

Investment Securities - Narrative (Details)	12 Months Ended
	Dec. 31, 2018USD ($)security	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Fair value of investments	$ 932,577,000	$ 446,047,000
Unrealized losses on available for sale securities	14,253,000	4,514,000
Unrealized losses in held to maturity portfolios	4,741,000	2,083,000
Carrying value of securities pledged as collateral	416,155,000	475,999,000	$ 572,896,000
Securities sold under repurchase agreements	116,691,000	136,639,000
Gross gains on securities sold	4,269,000	2,681,000	3,389,000
Gross losses from sale of available for sale securities	0	50,000	$ 0
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	951,571,000	452,644,000
Fair value of investments	$ 932,577,000	$ 446,047,000
Percent of the Corporation's available for sale and held to maturity portfolio	57.10%	28.60%
U.S. Government-Sponsored Mortgage-backed Securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Unrealized losses on available for sale securities	$ 8,396,000	$ 3,423,000
Available-for-sale number of securities in unrealized loss positions | security	105
Unrealized losses in held to maturity portfolios	$ 3,323,000	1,404,000
Held-to-maturity, number of securities in unrealized loss positions | security	76
State and municipal securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Unrealized losses on available for sale securities	$ 5,854,000	1,091,000
Available-for-sale number of securities in unrealized loss positions | security	221
Unrealized losses in held to maturity portfolios	$ 872,000	244,000
Held-to-maturity, number of securities in unrealized loss positions | security	41
U.S. Government-sponsored agency securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Unrealized losses on available for sale securities	$ 3,000
Available-for-sale number of securities in unrealized loss positions | security	4
Unrealized losses in held to maturity portfolios	$ 545,000	435,000
Held-to-maturity, number of securities in unrealized loss positions | security	5
Foreign Investment
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Unrealized losses on available for sale securities	$ 0
Unrealized losses in held to maturity portfolios	$ 1,000
Held-to-maturity, number of securities in unrealized loss positions | security	1

Investment Securities - Investm

Investment Securities - Investments' Gross Unrealized Losses and Fair Value Aggregated by Investment Category and Length of Time in Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	$ 432,522	$ 196,051
Less than 12 Months, Gross Unrealized Losses	6,361	1,718
12 Months or Longer, Fair Value	255,149	103,991
12 Months or Longer, Gross Unrealized Losses	7,892	2,796
Total, Fair Value	687,671	300,042
Total, Gross Unrealized Losses	14,253	4,514
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	117,780	74,926
Less than 12 Months, Gross Unrealized Losses	1,245	652
12 Months or Longer, Fair Value	127,126	71,079
12 Months or Longer, Gross Unrealized Losses	3,496	1,431
Total, Fair Value	244,906	146,005
Total, Gross Unrealized Losses	4,741	2,083
Available-for-sale Securities and Held-to-maturity Securities [Abstract] (Deprecated 2018-01-31)
Less than 12 Months, Fair Value	550,302	270,977
Less than 12 Months, Gross Unrealized Losses	7,606	2,370
12 Months or Longer, Fair Value	382,275	175,070
12 Months or Longer, Gross Unrealized Losses	11,388	4,227
Total, Fair Value	932,577	446,047
Total, Gross Unrealized Losses	18,994	6,597
Government Agency and Municipal Bonds and Notes
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	1,490
Less than 12 Months, Gross Unrealized Losses	3
12 Months or Longer, Fair Value
12 Months or Longer, Gross Unrealized Losses
Total, Fair Value	1,490
Total, Gross Unrealized Losses	3
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value		9,988
Less than 12 Months, Gross Unrealized Losses		131
12 Months or Longer, Fair Value	22,073	12,196
12 Months or Longer, Gross Unrealized Losses	545	304
Total, Fair Value	22,073	22,184
Total, Gross Unrealized Losses	545	435
State and municipal
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	234,431	13,296
Less than 12 Months, Gross Unrealized Losses	3,958	198
12 Months or Longer, Fair Value	38,028	35,324
12 Months or Longer, Gross Unrealized Losses	1,896	893
Total, Fair Value	272,459	48,620
Total, Gross Unrealized Losses	5,854	1,091
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	14,952	2,430
Less than 12 Months, Gross Unrealized Losses	369	36
12 Months or Longer, Fair Value	16,786	15,805
12 Months or Longer, Gross Unrealized Losses	503	208
Total, Fair Value	31,738	18,235
Total, Gross Unrealized Losses	872	244
U.S. Government-sponsored mortgage-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	196,601	182,755
Less than 12 Months, Gross Unrealized Losses	2,400	1,520
12 Months or Longer, Fair Value	217,121	68,667
12 Months or Longer, Gross Unrealized Losses	5,996	1,903
Total, Fair Value	413,722	251,422
Total, Gross Unrealized Losses	8,396	3,423
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value	102,828	62,508
Less than 12 Months, Gross Unrealized Losses	876	485
12 Months or Longer, Fair Value	87,268	43,078
12 Months or Longer, Gross Unrealized Losses	2,447	919
Total, Fair Value	190,096	105,586
Total, Gross Unrealized Losses	3,323	$ 1,404
Foreign Investment
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Less than 12 Months, Fair Value
Less than 12 Months, Gross Unrealized Losses
12 Months or Longer, Fair Value	999
12 Months or Longer, Gross Unrealized Losses	1
Total, Fair Value	999
Total, Gross Unrealized Losses	$ 1

Investment Securities - Amort_2

Investment Securities - Amortized Cost and Fair Value of Available for Sale Securities and Held to Maturity Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Available for Sale, Amortized Cost
Due in one year or less	$ 13,092
Due after one through five years	5,311
Due after five through ten years	73,280
Due after ten years	527,835
Amortized Cost	619,518
Total Investment Securities	1,149,727	$ 986,565
Available for Sale, Fair Value
Due in one year or less	13,144
Due after one through five years	5,378
Due after five through ten years	74,411
Due after ten years	526,815
Fair Value	619,748
Total Investment Securities	1,142,195	999,947
Held to Maturity, Amortized Cost
Due in one year or less	4,732
Due after one through five years	49,054
Due after five through ten years	62,873
Due after ten years	104,868
Amortized Cost	221,527
Amortized Cost	490,387	560,655
Held to Maturity, Fair Value
Due in one year or less	4,730
Due after one through five years	48,473
Due after five through ten years	64,163
Due after ten years	105,601
Fair Value	222,967
Total Investment Securities	489,217	$ 568,208
U.S. Government-sponsored mortgage-backed securities
Available for Sale, Amortized Cost
Without single maturity date	530,209
Available for Sale, Fair Value
Without single maturity date	522,447
Held to Maturity, Amortized Cost
Without single maturity date	268,860
Held to Maturity, Fair Value
Without single maturity date	$ 266,250

Loans and Allowance - Narrative

Loans and Allowance - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Loans held for sale	$ 4,778				$ 7,216				$ 4,778	$ 7,216
Allowance for loan losses	80,552				75,032				80,552	75,032	$ 66,037	$ 62,453
Increase in allowance for loan losses									5,520
Net charge offs									1,707
Increase in net charge offs									1,559
Provision for loan losses	1,664	$ 1,400	$ 1,663	$ 2,500	1,800	$ 2,083	$ 2,875	$ 2,385	7,227	9,143	5,657
Increase in provision for loan losses									1,916
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	7,224,467				6,751,199				7,224,467	6,751,199
Loans acquired with deteriorated credit quality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	15,784				24,954				15,784	24,954
Commercial and consumer loan | Loans acquired with deteriorated credit quality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,541				315				$ 1,541	315
Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of troubled debt restructured loans									79.00%
Residential
Receivables [Abstract]
Allowance for loan losses	14,322				13,537				$ 14,322	13,537	11,755	$ 11,139
Provision for loan losses									1,969	2,391	$ 1,515
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,494,578				1,476,786				1,494,578	1,476,786
Mortgage loans for which formal foreclosure proceedings are in process	800				2,302				800	2,302
Residential | Loans acquired with deteriorated credit quality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 1,293				$ 1,536				$ 1,293	$ 1,536

Loans and Allowance - Compositi

Loans and Allowance - Composition of Loan Portfolio by Loan Class (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 7,224,467	$ 6,751,199
Allowance for loan losses	(80,552)	(75,032)	$ (66,037)	$ (62,453)
Net Loans	7,143,915	6,676,167
Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,726,664	1,493,493
Agricultural production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	92,404	121,757
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	545,729	612,219
Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,832,102	2,562,691
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	966,421	962,765
Allowance for loan losses	(14,322)	(13,537)	(11,755)	(11,139)
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	528,157	514,021
Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	99,788	86,935
Allowance for loan losses	(3,964)	(3,732)	(2,923)	(2,689)
Lease financing receivables, net of unearned income
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,600	2,527
Allowance for loan losses	(2)	(2)	$ (2)	$ (2)
Other commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 431,602	$ 394,791

Loans and Allowance - Changes i

Loans and Allowance - Changes in Allowance for Loan Losses by Loan Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for loan losses:
Beginning balance				$ 75,032				$ 66,037	$ 75,032	$ 66,037	$ 62,453
Provision for losses	$ 1,664	$ 1,400	$ 1,663	2,500	$ 1,800	$ 2,083	$ 2,875	2,385	7,227	9,143	5,657
Recoveries on loans									6,276	4,880	5,356
Loans charged off									(7,983)	(5,028)	(7,429)
Ending balance	80,552				75,032				80,552	75,032	66,037
Commercial
Allowance for loan losses:
Beginning balance				30,418				27,696	30,418	27,696	26,478
Provision for losses									2,097	2,515	1,876
Recoveries on loans									2,456	1,590	1,806
Loans charged off									(2,316)	(1,383)	(2,464)
Ending balance	32,655				30,418				32,655	30,418	27,696
Commercial Real Estate
Allowance for loan losses:
Beginning balance				27,343				23,661	27,343	23,661	22,145
Provision for losses									2,482	3,159	1,834
Recoveries on loans									2,525	2,260	2,090
Loans charged off									(2,741)	(1,737)	(2,408)
Ending balance	29,609				27,343				29,609	27,343	23,661
Consumer
Allowance for loan losses:
Beginning balance				3,732				2,923	3,732	2,923	2,689
Provision for losses									679	1,078	432
Recoveries on loans									302	324	369
Loans charged off									(749)	(593)	(567)
Ending balance	3,964				3,732				3,964	3,732	2,923
Residential
Allowance for loan losses:
Beginning balance				13,537				11,755	13,537	11,755	11,139
Provision for losses									1,969	2,391	1,515
Recoveries on loans									993	706	1,091
Loans charged off									(2,177)	(1,315)	(1,990)
Ending balance	14,322				13,537				14,322	13,537	11,755
Finance Leases
Allowance for loan losses:
Beginning balance				$ 2				$ 2	2	2	2
Provision for losses
Recoveries on loans
Loans charged off
Ending balance	$ 2				$ 2				$ 2	$ 2	$ 2

Loans and Allowance - Allowance

Loans and Allowance - Allowance for Credit Losses and Loan Portfolio by Loan Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment	$ 1,872	$ 1,637
Allowance balances - Collectively evaluated for impairment	78,680	73,395
Total allowance for loan losses	80,552	75,032	$ 66,037	$ 62,453
Loan balances - Individually evaluated for impairment	22,025	23,211
Loan balances - Collectively evaluated for impairment	7,186,658	6,703,034
Loans	7,224,467	6,751,199
Loans acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	15,784	24,954
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment		666
Allowance balances - Collectively evaluated for impairment	32,655	29,752
Total allowance for loan losses	32,655	30,418	27,696	26,478
Loan balances - Individually evaluated for impairment	1,838	3,345
Loan balances - Collectively evaluated for impairment	2,246,730	2,005,275
Loans	2,250,670	2,010,041
Commercial | Loans acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	2,102	1,421
Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment	1,435	567
Allowance balances - Collectively evaluated for impairment	28,174	26,776
Total allowance for loan losses	29,609	27,343	23,661	22,145
Loan balances - Individually evaluated for impairment	17,756	17,432
Loan balances - Collectively evaluated for impairment	3,347,686	3,135,481
Loans	3,377,831	3,174,910
Commercial Real Estate | Loans acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	12,389	21,997
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment	1
Allowance balances - Collectively evaluated for impairment	3,963	3,732
Total allowance for loan losses	3,964	3,732	2,923	2,689
Loan balances - Individually evaluated for impairment	18	5
Loan balances - Collectively evaluated for impairment	99,770	86,930
Loans	99,788	86,935
Consumer | Loans acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans
Residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment	436	404
Allowance balances - Collectively evaluated for impairment	13,886	13,133
Total allowance for loan losses	14,322	13,537	11,755	11,139
Loan balances - Individually evaluated for impairment	2,413	2,429
Loan balances - Collectively evaluated for impairment	1,490,872	1,472,821
Loans	1,494,578	1,476,786
Residential | Loans acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	1,293	1,536
Finance Leases
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance balances - Individually evaluated for impairment
Allowance balances - Collectively evaluated for impairment	2	2
Total allowance for loan losses	2	2	$ 2	$ 2
Loan balances - Individually evaluated for impairment
Loan balances - Collectively evaluated for impairment	1,600	2,527
Loans	1,600	2,527
Finance Leases | Loans acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans

Loans and Allowance - Summary o

Loans and Allowance - Summary of Non-Accrual Loans by Loan Class (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 26,148	$ 28,724
Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,803	3,275
Agriculture production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	679	1,027
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	8,667	65
Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	8,156	12,951
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	4,966	9,444
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,481	1,928
Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	42	34
Other commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 354

Loans and Allowance - Composi_2

Loans and Allowance - Composition of Impaired Loans by Loan Class (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unpaid Principal Balance
Impaired loans with no related allowance	$ 14,555	$ 25,979	$ 29,365
Impaired loans with related allowance	10,501	6,123	6,155
Total Impaired Loans	25,056	32,102	35,520
Recorded Investment
Impaired loans with no related allowance	11,594	17,931	21,227
Impaired loans with related allowance	10,431	5,280	4,788
Total Impaired Loans	22,025	23,211	26,015
Related Allowance	1,872	1,637	888
Average Recorded Investment
Impaired loans with no related allowance	15,824	22,752	22,775
Impaired loans with related allowance	10,448	6,135	4,818
Total Impaired Loans	26,272	28,887	27,593
Interest Income Recognized
Impaired loans with no related allowance	168	360	327
Impaired loans with related allowance	68	39	20
Total Impaired Loans	236	399	347
Commercial and industrial loans
Unpaid Principal Balance
Impaired loans with no related allowance	828	7,611	4,028
Impaired loans with related allowance		812
Recorded Investment
Impaired loans with no related allowance	806	1,536	1,696
Impaired loans with related allowance		782
Related Allowance		552
Average Recorded Investment
Impaired loans with no related allowance	833	3,839	1,770
Impaired loans with related allowance		1,517
Interest Income Recognized
Impaired loans with no related allowance			37
Impaired loans with related allowance
Agriculture production financing and other loans to farmers
Unpaid Principal Balance
Impaired loans with no related allowance	679	732	367
Impaired loans with related allowance		357	660
Recorded Investment
Impaired loans with no related allowance	679	700	338
Impaired loans with related allowance		327	660
Related Allowance		114	36
Average Recorded Investment
Impaired loans with no related allowance	679	762	357
Impaired loans with related allowance		327	690
Interest Income Recognized
Impaired loans with no related allowance
Impaired loans with related allowance
Construction
Unpaid Principal Balance
Impaired loans with no related allowance	1,352
Impaired loans with related allowance	7,978
Recorded Investment
Impaired loans with no related allowance	614
Impaired loans with related allowance	7,977
Related Allowance	1,429
Average Recorded Investment
Impaired loans with no related allowance	835
Impaired loans with related allowance	7,977
Interest Income Recognized
Impaired loans with no related allowance
Commercial and farmland
Unpaid Principal Balance
Impaired loans with no related allowance	11,176	16,758	22,828
Impaired loans with related allowance	171	2,988	4,237
Recorded Investment
Impaired loans with no related allowance	8,994	15,163	17,752
Impaired loans with related allowance	171	2,269	2,985
Related Allowance	6	567	553
Average Recorded Investment
Impaired loans with no related allowance	12,975	17,495	18,944
Impaired loans with related allowance	171	2,379	2,990
Interest Income Recognized
Impaired loans with no related allowance	165	360	288
Impaired loans with related allowance
Residential
Unpaid Principal Balance
Impaired loans with no related allowance	118	833	2,073
Impaired loans with related allowance	1,958	1,616	968
Recorded Investment
Impaired loans with no related allowance	100	519	1,402
Impaired loans with related allowance	1,907	1,572	877
Related Allowance	362	327	233
Average Recorded Investment
Impaired loans with no related allowance	101	635	1,665
Impaired loans with related allowance	1,915	1,580	872
Interest Income Recognized
Impaired loans with no related allowance	3		2
Impaired loans with related allowance	57	28	14
Home equity
Unpaid Principal Balance
Impaired loans with no related allowance	49	40	60
Impaired loans with related allowance	376	350	290
Recorded Investment
Impaired loans with no related allowance	48	8	30
Impaired loans with related allowance	358	330	266
Related Allowance	74	77	66
Average Recorded Investment
Impaired loans with no related allowance	48	14	30
Impaired loans with related allowance	365	332	266
Interest Income Recognized
Impaired loans with no related allowance
Impaired loans with related allowance	10	11	6
Individuals' loans for household and other personal expenditures
Unpaid Principal Balance
Impaired loans with no related allowance		5	9
Impaired loans with related allowance	18
Recorded Investment
Impaired loans with no related allowance		5	9
Impaired loans with related allowance	18
Related Allowance	1
Average Recorded Investment
Impaired loans with no related allowance		7	9
Impaired loans with related allowance	20
Interest Income Recognized
Impaired loans with no related allowance
Impaired loans with related allowance	1
Other commercial loans
Unpaid Principal Balance
Impaired loans with no related allowance	353
Recorded Investment
Impaired loans with no related allowance	353
Average Recorded Investment
Impaired loans with no related allowance	353
Interest Income Recognized
Impaired loans with no related allowance

Loans and Allowance - Credit Qu

Loans and Allowance - Credit Quality of Loan Portfolio by Loan Class (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 7,224,467	$ 6,751,199
Commercial and industrial loans
Financing Receivable, Recorded Investment [Line Items]
Loans	1,726,664	1,493,493
Agricultural production financing and other loans to farmers
Financing Receivable, Recorded Investment [Line Items]
Loans	92,404	121,757
Construction
Financing Receivable, Recorded Investment [Line Items]
Loans	545,729	612,219
Commercial and farmland
Financing Receivable, Recorded Investment [Line Items]
Loans	2,832,102	2,562,691
Residential
Financing Receivable, Recorded Investment [Line Items]
Loans	966,421	962,765
Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	528,157	514,021
Individuals' loans for household and other personal expenditures
Financing Receivable, Recorded Investment [Line Items]
Loans	99,788	86,935
Lease financing receivables, net of unearned income
Financing Receivable, Recorded Investment [Line Items]
Loans	1,600	2,527
Other commercial loans
Financing Receivable, Recorded Investment [Line Items]
Loans	431,602	394,791
Commercial Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	5,528,751	5,099,464
Commercial Pass | Commercial and industrial loans
Financing Receivable, Recorded Investment [Line Items]
Loans	1,660,879	1,418,401
Commercial Pass | Agricultural production financing and other loans to farmers
Financing Receivable, Recorded Investment [Line Items]
Loans	78,446	73,800
Commercial Pass | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans	492,358	587,906
Commercial Pass | Commercial and farmland
Financing Receivable, Recorded Investment [Line Items]
Loans	2,669,491	2,408,329
Commercial Pass | Residential
Financing Receivable, Recorded Investment [Line Items]
Loans	170,075	185,725
Commercial Pass | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	24,653	28,554
Commercial Pass | Lease financing receivables, net of unearned income
Financing Receivable, Recorded Investment [Line Items]
Loans	1,600	2,527
Commercial Pass | Other commercial loans
Financing Receivable, Recorded Investment [Line Items]
Loans	431,249	394,222
Commercial Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	115,342	154,573
Commercial Special Mention | Commercial and industrial loans
Financing Receivable, Recorded Investment [Line Items]
Loans	23,246	51,336
Commercial Special Mention | Agricultural production financing and other loans to farmers
Financing Receivable, Recorded Investment [Line Items]
Loans	5,966	27,502
Commercial Special Mention | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans	2,185	828
Commercial Special Mention | Commercial and farmland
Financing Receivable, Recorded Investment [Line Items]
Loans	76,037	70,074
Commercial Special Mention | Residential
Financing Receivable, Recorded Investment [Line Items]
Loans	7,373	4,376
Commercial Special Mention | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	535	457
Commercial Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	161,929	129,218
Commercial Substandard | Commercial and industrial loans
Financing Receivable, Recorded Investment [Line Items]
Loans	42,539	23,386
Commercial Substandard | Agricultural production financing and other loans to farmers
Financing Receivable, Recorded Investment [Line Items]
Loans	7,992	20,018
Commercial Substandard | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans	24,224	981
Commercial Substandard | Commercial and farmland
Financing Receivable, Recorded Investment [Line Items]
Loans	84,288	79,769
Commercial Substandard | Residential
Financing Receivable, Recorded Investment [Line Items]
Loans	2,076	4,209
Commercial Substandard | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	457	286
Commercial Substandard | Lease financing receivables, net of unearned income
Financing Receivable, Recorded Investment [Line Items]
Loans
Commercial Substandard | Other commercial loans
Financing Receivable, Recorded Investment [Line Items]
Loans	353	569
Commercial Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans		2,407
Commercial Doubtful | Commercial and industrial loans
Financing Receivable, Recorded Investment [Line Items]
Loans		370
Commercial Doubtful | Agricultural production financing and other loans to farmers
Financing Receivable, Recorded Investment [Line Items]
Loans		387
Commercial Doubtful | Commercial and farmland
Financing Receivable, Recorded Investment [Line Items]
Loans		1,536
Commercial Doubtful | Residential
Financing Receivable, Recorded Investment [Line Items]
Loans		114
Commercial Loss
Financing Receivable, Recorded Investment [Line Items]
Loans		50
Commercial Loss | Agricultural production financing and other loans to farmers
Financing Receivable, Recorded Investment [Line Items]
Loans		50
Consumer Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	1,410,521	1,354,790
Consumer Performing | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans	25,419	22,374
Consumer Performing | Commercial and farmland
Financing Receivable, Recorded Investment [Line Items]
Loans	2,285	2,980
Consumer Performing | Residential
Financing Receivable, Recorded Investment [Line Items]
Loans	782,080	759,900
Consumer Performing | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	500,996	482,661
Consumer Performing | Individuals' loans for household and other personal expenditures
Financing Receivable, Recorded Investment [Line Items]
Loans	99,741	86,875
Consumer Non Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	7,924	10,697
Consumer Non Performing | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans	1,543	130
Consumer Non Performing | Commercial and farmland
Financing Receivable, Recorded Investment [Line Items]
Loans	1	3
Consumer Non Performing | Residential
Financing Receivable, Recorded Investment [Line Items]
Loans	4,817	8,441
Consumer Non Performing | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	1,516	2,063
Consumer Non Performing | Individuals' loans for household and other personal expenditures
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 47	$ 60

Loans and Allowance - Past Due

Loans and Allowance - Past Due Aging of Loan Portfolio by Loan Class (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 7,186,609	$ 6,703,256
Loans 90 Days or More Past Due And Accruing	1,855	924
Non-Accrual	26,148	28,724
Total Past Due & Non-Accrual	37,858	47,943
Total	7,224,467	6,751,199
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	8,794	16,773
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,061	1,522
Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,723,337	1,487,221
Loans 90 Days or More Past Due And Accruing	249
Non-Accrual	1,803	3,275
Total Past Due & Non-Accrual	3,327	6,272
Total	1,726,664	1,493,493
Commercial and industrial loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,093	2,967
Commercial and industrial loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	182	30
Agricultural production financing and other loans to farmers
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	89,440	120,720
Loans 90 Days or More Past Due And Accruing
Non-Accrual	679	1,027
Total Past Due & Non-Accrual	2,964	1,037
Total	92,404	121,757
Agricultural production financing and other loans to farmers | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,285	10
Agricultural production financing and other loans to farmers | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due
Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	535,520	610,896
Loans 90 Days or More Past Due And Accruing	1,478	65
Non-Accrual	8,667	65
Total Past Due & Non-Accrual	10,209	1,323
Total	545,729	612,219
Construction | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	64	1,193
Construction | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due
Commercial and farmland
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	2,822,515	2,542,048
Loans 90 Days or More Past Due And Accruing		603
Non-Accrual	8,156	12,951
Total Past Due & Non-Accrual	9,587	20,643
Total	2,832,102	2,562,691
Commercial and farmland | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,253	6,923
Commercial and farmland | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	178	166
Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	959,252	948,947
Loans 90 Days or More Past Due And Accruing	17	56
Non-Accrual	4,966	9,444
Total Past Due & Non-Accrual	7,169	13,818
Total	966,421	962,765
Residential | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,756	4,010
Residential | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	430	308
Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	524,198	510,362
Loans 90 Days or More Past Due And Accruing	107	175
Non-Accrual	1,481	1,928
Total Past Due & Non-Accrual	3,959	3,659
Total	528,157	514,021
Home equity | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,164	1,372
Home equity | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	207	184
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	99,499	85,744
Loans 90 Days or More Past Due And Accruing	4	25
Non-Accrual	42	34
Total Past Due & Non-Accrual	289	1,191
Total	99,788	86,935
Consumer | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	179	298
Consumer | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	64	834
Lease financing receivables, net of unearned income
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,600	2,527
Non-Accrual
Total Past Due & Non-Accrual
Total	1,600	2,527
Other commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	431,248	394,791
Non-Accrual	354
Total Past Due & Non-Accrual	354
Total	431,602	394,791
Other commercial loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due

Loans and Allowance - Summary_2

Loans and Allowance - Summary of Troubled Debt Restructurings (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)loan	Dec. 31, 2017USD ($)loan
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	$ 721	$ 3,004
Post-Modification Recorded Balance	$ 719	$ 2,902
Number of Loans | loan	18	34
Commercial and industrial loans
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance		$ 599
Post-Modification Recorded Balance		$ 376
Number of Loans | loan		3
Agriculture production financing and other loans to farmers
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance		$ 387
Post-Modification Recorded Balance		$ 387
Number of Loans | loan		3
Commercial and farmland
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	$ 85	$ 1,022
Post-Modification Recorded Balance	$ 85	$ 1,156
Number of Loans | loan	1	8
Residential
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	$ 490	$ 788
Post-Modification Recorded Balance	$ 487	$ 862
Number of Loans | loan	11	15
Home equity
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	$ 81	$ 195
Post-Modification Recorded Balance	$ 81	$ 107
Number of Loans | loan	3	4
Individuals' loans for household and other personal expenditures
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	$ 65	$ 13
Post-Modification Recorded Balance	$ 66	$ 14
Number of Loans | loan	3	1

Loans and Allowance - Summary_3

Loans and Allowance - Summary of Troubled Debt Restructurings by Modification (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Total Modification	$ 777	$ 2,717
Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification	249	1,295
Rate Modification
Financing Receivable, Modifications [Line Items]
Total Modification	289	939
Combination
Financing Receivable, Modifications [Line Items]
Total Modification	239	483
Commercial and industrial loans
Financing Receivable, Modifications [Line Items]
Total Modification		369
Commercial and industrial loans | Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification		203
Commercial and industrial loans | Combination
Financing Receivable, Modifications [Line Items]
Total Modification		166
Agriculture production financing and other loans to farmers
Financing Receivable, Modifications [Line Items]
Total Modification		387
Agriculture production financing and other loans to farmers | Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification		387
Agriculture production financing and other loans to farmers | Rate Modification
Financing Receivable, Modifications [Line Items]
Total Modification
Commercial and farmland
Financing Receivable, Modifications [Line Items]
Total Modification	85	996
Commercial and farmland | Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification	85	705
Commercial and farmland | Rate Modification
Financing Receivable, Modifications [Line Items]
Total Modification		59
Commercial and farmland | Combination
Financing Receivable, Modifications [Line Items]
Total Modification		232
Residential
Financing Receivable, Modifications [Line Items]
Total Modification	448	846
Residential | Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification
Residential | Rate Modification
Financing Receivable, Modifications [Line Items]
Total Modification	209	761
Residential | Combination
Financing Receivable, Modifications [Line Items]
Total Modification	239	85
Home equity
Financing Receivable, Modifications [Line Items]
Total Modification	180	105
Home equity | Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification	106
Home equity | Rate Modification
Financing Receivable, Modifications [Line Items]
Total Modification	74	105
Home equity | Combination
Financing Receivable, Modifications [Line Items]
Total Modification
Individuals' loans for household and other personal expenditures
Financing Receivable, Modifications [Line Items]
Total Modification	64	14
Individuals' loans for household and other personal expenditures | Term Modification
Financing Receivable, Modifications [Line Items]
Total Modification	58
Individuals' loans for household and other personal expenditures | Rate Modification
Financing Receivable, Modifications [Line Items]
Total Modification	$ 6	14
Individuals' loans for household and other personal expenditures | Combination
Financing Receivable, Modifications [Line Items]
Total Modification

Loans and Allowance - Subsequen

Loans and Allowance - Subsequent Default (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)loan	Dec. 31, 2017USD ($)loan
Financing Receivable, Impaired [Line Items]
Number of Loans | loan	2	5
Recorded Balance | $	$ 75	$ 337
Commercial and farmland
Financing Receivable, Impaired [Line Items]
Number of Loans | loan		1
Recorded Balance | $		$ 14
Residential
Financing Receivable, Impaired [Line Items]
Number of Loans | loan	2	4
Recorded Balance | $	$ 75	$ 323

Accounting for Certain Loans _3

Accounting for Certain Loans Acquired in a Purchase - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Loans acquired with deteriorated credit quality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding balance amount of loans acquired	$ 17.3	$ 25.3

Accounting for Certain Loans _4

Accounting for Certain Loans Acquired in a Purchase - Accretable Yield or Income Expected to be Collected (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Beginning balance	$ 2,890	$ 3,950	$ 5,612
Additions		1,608
Accretion	(4,118)	(6,749)	(6,577)
Reclassification from nonaccretable	3,387	4,748	5,172
Disposals	(16)	(667)	(257)
Ending balance	$ 2,143	$ 2,890	$ 3,950

Accounting for Certain Loans _5

Accounting for Certain Loans Acquired in a Purchase - Contractually Required Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Jul. 14, 2017	May 19, 2017
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required payments receivable at acquisition date	$ 20,314
Nonaccretable difference	11,243
Expected cash flows at acquisition date	9,071
Accretable difference	1,608
Basis in loans at acquisition date	7,463
IAB
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required payments receivable at acquisition date	14,131	$ 14,131
Nonaccretable difference	8,352
Expected cash flows at acquisition date	5,779
Accretable difference	941
Basis in loans at acquisition date	4,838	$ 4,838
Arlington Bank
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required payments receivable at acquisition date	6,183		$ 6,183
Nonaccretable difference	2,891
Expected cash flows at acquisition date	3,292
Accretable difference	667
Basis in loans at acquisition date	$ 2,625		$ 2,625

Premises and Equipment - Summar

Premises and Equipment - Summary of Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Premises and Equipment [Line Items]
Total Cost	$ 233,626	$ 228,827
Accumulated Depreciation and Amortization	(140,206)	(132,975)
Net	93,420	95,852
Land
Premises and Equipment [Line Items]
Total Cost	21,762	22,042
Buildings and Leasehold Improvements
Premises and Equipment [Line Items]
Total Cost	125,366	124,441
Equipment
Premises and Equipment [Line Items]
Total Cost	$ 86,498	$ 82,344

Premises and Equipment - Narrat

Premises and Equipment - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jul. 14, 2017	May 19, 2017
Premises and Equipment [Line Items]
Rent expense	$ 4,369	$ 4,072	$ 4,586
IAB
Premises and Equipment [Line Items]
Premises and equipment acquired				$ 10,107
Arlington Bank
Premises and Equipment [Line Items]
Premises and equipment acquired					$ 1,986

Premises and Equipment - Schedu

Premises and Equipment - Schedule of Future Minimum Rental Payments for Operating Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Property, Plant and Equipment [Abstract]
2,019	$ 3,721
2,020	3,584
2,021	3,283
2,022	3,150
2,023	2,622
After 2,023	12,495
Total Future Minimum Obligations	$ 28,855

Goodwill - Narrative (Details)

Goodwill - Narrative (Details) - USD ($)	May 19, 2017	Dec. 31, 2018	Dec. 31, 2017	Jul. 14, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill		$ 445,355,000	$ 445,355,000		$ 244,000,000
Measurement period adjustment			(469,000)
Goodwill impairment loss		$ 0	$ 0
IAB
Business Acquisition [Line Items]
Goodwill				$ 153,636,000
Arlington Bank
Business Acquisition [Line Items]
Goodwill	$ 47,719,000
Measurement period adjustment	$ 469,000

Goodwill - Rollforward (Details

Goodwill - Rollforward (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 244,000
Goodwill acquired	201,824
Measurement period adjustment	(469)
Ending balance	$ 445,355

Other Intangibles - Narrative (

Other Intangibles - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jul. 14, 2017	May 19, 2017
Business Acquisition [Line Items]
Intangible asset amortization	$ 6,719	$ 5,647	$ 3,910
IAB
Business Acquisition [Line Items]
Core deposit intangible				$ 17,403
Arlington Bank
Business Acquisition [Line Items]
Core deposit intangible					$ 4,526
Core deposits | IAB
Business Acquisition [Line Items]
Core deposit intangible				13,638
Core deposits | Arlington Bank
Business Acquisition [Line Items]
Core deposit intangible					$ 4,526
Noncompete agreements | IAB
Business Acquisition [Line Items]
Core deposit intangible				$ 3,765

Other Intangibles - Schedule of

Other Intangibles - Schedule of Core Deposit and Other Intangibles (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 85,869	$ 63,940
Accumulated amortization	(61,440)	(54,721)
Core Deposit and Other Intangibles	24,429	31,148
Core deposits
Acquired Finite-Lived Intangible Assets [Line Items]
Intangibles acquired		18,164
Other intangible
Acquired Finite-Lived Intangible Assets [Line Items]
Intangibles acquired		$ 3,765

Other Intangibles - Schedule _2

Other Intangibles - Schedule of Estimated Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amortization Expense
2,019	$ 5,169
2,020	3,632
2,021	3,427
2,022	3,325
2,023	3,175
After 2,023	5,701
Core Deposit and Other Intangibles	$ 24,429	$ 31,148

Deposits - Schedule of Deposits

Deposits - Schedule of Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Demand deposits	$ 3,985,178	$ 3,746,654
Savings deposits	2,282,701	1,994,366
Certificates and other time deposits of $100,000 or more	593,592	468,895
Other certificates and time deposits	646,682	581,894
Brokered deposits	246,440	380,721
Total Deposits	7,754,593	7,172,530
Cash amount that exceeded federally insured limits	$ 3,800,000	$ 3,200,000

Deposits - Schedule of Contract

Deposits - Schedule of Contractual Maturities of Time Deposits (Details) $ in Thousands	Dec. 31, 2018USD ($)
Certificates and Other Time Deposits
2,019	$ 1,007,653
2,020	361,663
2,021	70,327
2,022	27,535
2,023	17,977
After 2,023	1,559
Total	$ 1,486,714

Transfers Accounted for as Se_3

Transfers Accounted for as Secured Borrowings (Details) - U.S. Government-sponsored mortgage-backed securities - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets Sold under Agreements to Repurchase [Line Items]
Collateral pledged for all repurchase agreements accounted for as secured borrowings	$ 113,512	$ 136,623
Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Collateral pledged for all repurchase agreements accounted for as secured borrowings	104,883	126,187
Up to 30 Days
Assets Sold under Agreements to Repurchase [Line Items]
Collateral pledged for all repurchase agreements accounted for as secured borrowings	1,014	1,340
30-90 Days
Assets Sold under Agreements to Repurchase [Line Items]
Collateral pledged for all repurchase agreements accounted for as secured borrowings	7,615	1,500
Greater Than 90 Days
Assets Sold under Agreements to Repurchase [Line Items]
Collateral pledged for all repurchase agreements accounted for as secured borrowings		$ 7,596

Borrowings - Schedule of Debt (

Borrowings - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Federal funds purchased	$ 104,000	$ 144,038
Securities sold under repurchase agreements	113,512	136,623
Federal Home Loan Bank advances	314,986	414,377
Subordinated debentures and term loans	138,463	139,349
Total Borrowings	$ 670,961	$ 834,387

Borrowings - Narrative (Details

Borrowings - Narrative (Details)	Jul. 14, 2017USD ($)	Aug. 10, 2015USD ($)	Nov. 01, 2013USD ($)investor	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2015USD ($)	Sep. 15, 2012	Jul. 02, 2007USD ($)
Debt Instrument [Line Items]
Total available remaining borrowing capacity from FHLB				$ 629,237,000
Puttable advances with the FHLB				$ 314,986,000	$ 414,377,000
Debt face amount			$ 70,000,000
Private debt issuance, number of institutional investors | investor			4
5.00% Senior Notes Due 2028
Debt Instrument [Line Items]
Redemption price (percent)				100.00%
5% Senior Notes Due 2028 and 6.75% Subordinated Notes due 2028
Debt Instrument [Line Items]
Debt term with fixed interest rate			10 years
Putable Advances
Debt Instrument [Line Items]
Puttable advances with the FHLB				$ 45,000,000
Minimum
Debt Instrument [Line Items]
Required value of assets pledged as collateral as a percentage to outstanding advances				145.00%
Interest rate, minimum (as a percent)				0.96%
Maximum
Debt Instrument [Line Items]
Interest rate, minimum (as a percent)				5.09%
Securities Sold Under Repurchase Agreements
Debt Instrument [Line Items]
Maximum amount of outstanding agreements				$ 143,016,000	145,883,000
Total of average agreements				124,762,000	134,401,000
Debt outstanding				113,512,000
Subordinated Debentures and Term Loans
Debt Instrument [Line Items]
Debt outstanding				$ 138,463,000	$ 139,349,000
Subordinated Debenture | 6.75% Subordinated Notes Due 2028
Debt Instrument [Line Items]
Debt face amount			$ 65,000,000
Interest rate on notes (as a percent)			6.75%
Redemption price (percent)				100.00%
Subordinated Debenture | Three-Month LIBOR | 6.75% Subordinated Notes Due 2028
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)				4.095%
Subordinated Debenture | First Merchant Capital Trust II
Debt Instrument [Line Items]
Debt outstanding				$ 51,702,000
Debt face amount								$ 56,702,000
Cancellation of debt, amount		$ 5,000,000
Gain from cancellation of debt		$ 1,250,000
Interest rate on notes (as a percent)				4.35%	3.15%		6.495%
Subordinated Debenture | First Merchant Capital Trust II | Three-Month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)				1.56%
Subordinated Debenture | Ameriana Capital Trust I
Debt Instrument [Line Items]
Debt face amount						$ 10,310,000
Interest rate on notes (as a percent)				4.29%	3.09%
Basis spread on variable rate (as a percent)				1.50%
Subordinated Debenture | Grabill Capital Trust I
Debt Instrument [Line Items]
Debt face amount	$ 10,310,000
Interest rate on notes (as a percent)				5.08%	3.96%
Basis spread on variable rate (as a percent)	2.60%
Senior Notes | 5.00% Senior Notes Due 2028
Debt Instrument [Line Items]
Debt face amount			$ 5,000,000
Interest rate on notes (as a percent)			5.00%
Senior Notes | Three-Month LIBOR | 5.00% Senior Notes Due 2028
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)				2.345%

Borrowings - Schedule of Maturi

Borrowings - Schedule of Maturities of Long Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Federal Funds Purchased
Maturities in Years Ending December 31:
2,019	$ 104,000
Total	104,000
Securities Sold Under Repurchase Agreements
Maturities in Years Ending December 31:
2,019	113,512
Total	113,512
Federal Home Loan Bank Advances
Maturities in Years Ending December 31:
2,019	113,713
2,020	41,273
2,021	55,000
2,022	45,000
2,023	35,000
After 2,023	25,000
Total	314,986
Subordinated Debentures and Term Loans
Maturities in Years Ending December 31:
2,019
After 2,023	142,322
ASC 805 fair value adjustments at acquisition	(3,859)
Total	$ 138,463	$ 139,349

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)interest_rate_swapinterest_rate_cap	Sep. 30, 2018USD ($)	Dec. 31, 2017USD ($)interest_rate_swapinterest_rate_cap
Derivative [Line Items]
Termination value of derivatives in a net liability position	$ 3,302
Derivative collateral posted	5,195
Not Designated as Hedging Instruments
Derivative [Line Items]
Notional amount of interest rate derivatives	477,776
Cash Flow Hedging
Derivative [Line Items]
Estimated amount to be transferred from OCI to earnings	$ 208
Interest Rate Swap
Derivative [Line Items]
Number of interest rate derivatives held | interest_rate_swap	4		5
Notional amount of interest rate derivatives	$ 46,000	$ 10,000	$ 56,000
Interest Rate Swap | Cash Flow Hedging | Trust Preferred Debt
Derivative [Line Items]
Notional amount of interest rate derivatives	26,000
Interest Rate Swap | Cash Flow Hedging | Federal Home Loan Bank Advances
Derivative [Line Items]
Notional amount of interest rate derivatives	$ 20,000
Interest Rate Cap
Derivative [Line Items]
Number of interest rate derivatives held | interest_rate_cap	1		1
Notional amount of interest rate derivatives	$ 13,000		$ 13,000
Interest Rate Cap | Cash Flow Hedging | Trust Preferred Debt
Derivative [Line Items]
Notional amount of interest rate derivatives	$ 13,000

Derivative Instruments and He_4

Derivative Instruments and Hedging Activities - Fair Value of Derivative Financial Instruments and Their Classification on Balance Sheet (Details) - Interest Rate Contracts - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivatives Designated as Hedging Instruments | Other Assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 135	$ 18
Derivatives Designated as Hedging Instruments | Other Liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	688	1,383
Derivatives Not Designated as Hedging Instruments | Other Assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	11,948	7,305
Derivatives Not Designated as Hedging Instruments | Other Liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 11,948	$ 7,305

Derivative Instruments and He_5

Derivative Instruments and Hedging Activities - Effect of Derivative Financial Instruments on Income Statement (Details) - Interest Rate Contracts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivatives Designated as Hedging Instruments | Interest expense
Derivative [Line Items]
Amount of Loss Reclassified from Other Comprehensive Income Into Income (Effective Portion)	$ (470)	$ (985)	$ (1,250)
Derivatives Designated as Hedging Instruments | Cash Flow Hedging
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income on Derivative (Effective Portion)	247	13
Not Designated as Hedging Instruments | Other income
Derivative [Line Items]
Amount of Gain (Loss) Recognized Income on Derivative			$ 211

Fair Values of Financial Inst_3

Fair Values of Financial Instruments - Fair Value Measurements of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	$ 1,142,195	$ 999,947
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale
Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	1,138,867	995,969
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	3,328	3,978
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swap liability
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap liability	12,636	8,688
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	13,582
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	602,842	522,750
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	522,443	470,866
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities		2,353
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	11,948	7,305
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	135	18
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	3,293	3,943
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | U.S. Government-sponsored mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	4
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	31
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities		4
Fair Value, Measurements, Recurring | Fair Value | Interest rate swap liability
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap liability	12,636	8,688
Fair Value, Measurements, Recurring | Fair Value | U.S. Government-sponsored agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	13,582
Fair Value, Measurements, Recurring | Fair Value | State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	606,135	526,693
Fair Value, Measurements, Recurring | Fair Value | U.S. Government-sponsored mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	522,447	470,866
Fair Value, Measurements, Recurring | Fair Value | Corporate obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	31	31
Fair Value, Measurements, Recurring | Fair Value | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities		2,357
Fair Value, Measurements, Recurring | Fair Value | Interest rate swap asset
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	11,948	7,305
Fair Value, Measurements, Recurring | Fair Value | Interest rate cap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	$ 135	$ 18

Fair Values of Financial Inst_4

Fair Values of Financial Instruments - Reconciliation of Beginning and Ending Balances of Recurring Fair Value Measurements using Significant Unobservable Level 3 Inputs (Details) - Fair Value, Measurements, Recurring - Available for Sale Securities - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Available for Sale Securities
Beginning Balance	$ 3,978	$ 5,169
Included in other comprehensive income	(49)	26
Principal payments	(601)	(1,217)
Ending balance	$ 3,328	$ 3,978

Fair Values of Financial Inst_5

Fair Values of Financial Instruments - Transfer Between Levels 1, 2 and 3 and Reasons for Transfers (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Transfer between in or out of Level 3	$ 0	$ 0

Fair Values of Financial Inst_6

Fair Values of Financial Instruments - Valuation Methodologies Used for Instruments Measured at Fair Value on Non-Recurring Basis (Details) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
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	$ 11,866	$ 9,576
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	657	859
Fair Value | Impaired Loans (collateral dependent)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset fair value	11,866	9,576
Fair Value | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset fair value	$ 657	$ 859

Fair Values of Financial Inst_7

Fair Values of Financial Instruments - Unobservable Inputs Used in Recurring and Nonrecurring Level 3 Fair Value Measurements Other Than Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Discounted cash flow | State and municipal securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 3,293	$ 3,943
Discounted cash flow | State and municipal securities | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Maturity Call Date	1 month	1 month
US Muni BQ curve	A-	A-
Discounted cash flow | State and municipal securities | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Maturity Call Date	20 years	20 years
US Muni BQ curve	BBB-	BBB-
Discounted cash flow | State and municipal securities | Maturity Call Date US Muni BQ curve Discount rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate	0.0069	0.0069
Discounted cash flow | State and municipal securities | Maturity Call Date US Muni BQ curve Discount rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate	0.05	0.05
Discounted cash flow | Corporate obligations and U.S. Government-sponsored mortgage backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 35	$ 35
Discounted cash flow | Corporate obligations and U.S. Government-sponsored mortgage backed securities | Risk free rate plus Premium for illiquidity | Three-Month LIBOR
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate	0.0200	0.0200
Collateral based measurements | Impaired loans (collateral dependent)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 11,866	$ 9,576
Collateral based measurements | Impaired loans (collateral dependent) | Discount to reflect current market conditions and ultimate collectability | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect current market conditions and ultimate collectability	0	0
Collateral based measurements | Impaired loans (collateral dependent) | Discount to reflect current market conditions and ultimate collectability | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect current market conditions and ultimate collectability	0.10	0.10
Collateral based measurements | Impaired loans (collateral dependent) | Discount to reflect current market conditions and ultimate collectability | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect current market conditions and ultimate collectability	0.06	0.01
Appraisals | Other real estate owned
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 657	$ 859
Appraisals | Other real estate owned | Discount to reflect current market conditions | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect current market conditions (percent)	0	0
Appraisals | Other real estate owned | Discount to reflect current market conditions | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect current market conditions (percent)	0.10	0.10
Appraisals | Other real estate owned | Discount to reflect current market conditions | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount to reflect current market conditions (percent)	0.04	0.02

Fair Values of Financial Inst_8

Fair Values of Financial Instruments - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Investment securities available for sale	$ 1,142,195	$ 999,947
Investment securities held to maturity	489,217	568,208
Loans held for sale	4,778	7,216
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	139,247	154,905
Interest-bearing time deposits	36,963	35,027
Investment securities available for sale
Liabilities:
Deposits	6,267,879	5,741,019
Significant Other Observable Inputs (Level 2)
Assets:
Investment securities available for sale	1,138,867	995,969
Investment securities held to maturity	481,377	556,305
Loans held for sale	4,778	7,216
Federal Home Loan Bank stock	24,588	23,825
Interest rate swap asset	12,083	7,323
Interest receivable	40,881	37,130
Liabilities:
Deposits	1,464,129	1,406,526
Borrowings:
Federal funds purchased	104,000	144,038
Securities sold under repurchase agreements	113,437	136,562
Federal Home Loan Bank advances	318,728	361,085
Subordinated debentures and term loans	127,298	120,085
Interest rate swap liability	12,636	8,688
Interest payable	5,607	4,390
Significant Unobservable Inputs (Level 3)
Assets:
Investment securities available for sale	3,328	3,978
Investment securities held to maturity	7,840	11,903
Loans	7,004,193	6,534,877
Carrying Amount
Assets:
Cash and cash equivalents	139,247	154,905
Interest-bearing time deposits	36,963	35,027
Investment securities available for sale	1,142,195	999,947
Investment securities held to maturity	490,387	560,655
Loans held for sale	4,778	7,216
Loans	7,143,915	6,676,167
Federal Home Loan Bank stock	24,588	23,825
Interest rate swap asset	12,083	7,323
Interest receivable	40,881	37,130
Liabilities:
Deposits	7,754,593	7,172,530
Borrowings:
Federal funds purchased	104,000	144,038
Securities sold under repurchase agreements	113,512	136,623
Federal Home Loan Bank advances	314,986	414,377
Subordinated debentures and term loans	138,463	139,349
Interest rate swap liability	12,636	8,688
Interest payable	$ 5,607	$ 4,390

Commitments and Contingent Li_3

Commitments and Contingent Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Loan commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Amounts of commitments	$ 2,684,806	$ 2,482,641
Standby letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Amounts of commitments	$ 32,862	$ 43,526

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Summary of Changes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 1,303,463	$ 901,657	$ 850,509
Other comprehensive income before reclassifications	(14,870)	12,340
Amounts reclassified from accumulated other comprehensive income	(3,018)	(1,667)	(2,422)
Period change	(17,888)	10,673	(12,219)
Reclassification adjustment under ASU 2018-02	0
Ending balance	1,408,260	1,303,463	901,657
Total
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(2,908)	(13,581)	(1,362)
Period change	(17,888)	10,673	(12,219)
Reclassification adjustment under ASU 2018-02	(626)
Ending balance	(21,422)	(2,908)	(13,581)
Unrealized Gains (Losses) on Securities Available for Sale
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	8,970	1,035
Other comprehensive income before reclassifications	(13,872)	9,645
Amounts reclassified from accumulated other comprehensive income	(3,373)	(1,710)	(2,203)
Period change	(17,245)	7,935
Reclassification adjustment under ASU 2018-02	1,932
Ending balance	(6,343)	8,970	1,035
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(1,125)	(1,774)
Other comprehensive income before reclassifications	437	9
Amounts reclassified from accumulated other comprehensive income	371	640	813
Period change	808	649
Reclassification adjustment under ASU 2018-02	(242)
Ending balance	(559)	(1,125)	(1,774)
Unrealized Gains (Losses) on Defined Benefit Plans
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(10,753)	(12,842)
Other comprehensive income before reclassifications	(1,435)	2,686
Amounts reclassified from accumulated other comprehensive income	(16)	(597)
Period change	(1,451)	2,089
Reclassification adjustment under ASU 2018-02	(2,316)
Ending balance	$ (14,520)	$ (10,753)	$ (12,842)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Reclassifications (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on sales of available for sale securities									$ 4,269	$ 2,631	$ 3,389
Income tax expense	$ (5,949)	$ (8,478)	$ (7,961)	$ (6,611)	$ (15,210)	$ (7,939)	$ (7,207)	$ (7,168)	(28,999)	(37,524)	(27,609)
Subordinated debentures and term loans									8,233	7,572	7,185
Salaries and employee benefits									131,704	119,812	102,552
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax									3,018	1,667	2,422
Unrealized gains (losses) on available for sale securities
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax									3,373	1,710	2,203
Unrealized gains (losses) on cash flow hedges
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax									(371)	(640)	(813)
Unrealized gains (losses) on defined benefit plans
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax									16	597
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) | Unrealized gains (losses) on available for sale securities
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on sales of available for sale securities									4,269	2,631	3,389
Income tax expense									(896)	(921)	(1,186)
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) | Unrealized gains (losses) on cash flow hedges
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense									99	345	437
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) | Unrealized gains (losses) on cash flow hedges | Interest Rate Contracts
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Subordinated debentures and term loans									(470)	(985)	(1,250)
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) | Unrealized gains (losses) on defined benefit plans
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense									(4)	(209)	(556)
Salaries and employee benefits									20	806	1,588
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax									$ 16	$ 597	$ 1,032

Regulatory Capital and Divide_3

Regulatory Capital and Dividends - Schedule of Actual and Required Capital (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Total Risk-Based Capital
Actual	$ 1,177,725	$ 1,048,757
Prompt Corrective Action Thresholds, Adequate Capital	644,871	612,848
Tier 1 Capital to Risk-weighted Assets, Amount
Actual	1,032,173	908,725
Prompt Corrective Action Thresholds, Adequate Capital	483,653	459,636
Common Equity Tier One Capital to Risk-weighted Assets, Amount
Actual	966,032	842,806
Prompt Corrective Action Thresholds, Adequate Capital	362,740	344,727
Tier I Capital to Average Assets, Amount
Actual	1,032,173	908,725
Prompt Corrective Action Thresholds, Adequate Capital	$ 378,379	$ 348,407
Risk Based Ratios
Total Capital to Risk-weighted Assets, Actual Ratio	14.61%	13.69%
Total Capital to Risk-weighted Assets, Prompt Corrective Action Thresholds, Adequate Capital Ratio	8.00%	8.00%
Tier 1 Capital to Risk-Weighted Assets	12.80%	11.86%
Tier I Capital to Risk-weighted Assets, Prompt Corrective Action Thresholds, Adequate Capital Ratio	6.00%	6.00%
Common Equity Tier 1 Capital Ratio (Regulatory)	11.98%	11.00%
Common Equity Tier 1 Capital to Risk-weighted Assets, Prompt Corrective Action Thresholds, Adequately Capitalized Ratio	4.50%	4.50%
Leverage Ratios
Tier 1 Capital to Average Assets	10.91%	10.43%
Tier I Capital to Average Assets, Prompt Corrective Action Thresholds, Adequate Capital Ratio	4.00%	4.00%
First Merchants Bank
Total Risk-Based Capital
Actual	$ 1,092,602	$ 1,016,355
Prompt Corrective Action Thresholds, Adequate Capital	649,531	617,477
Prompt Corrective Action Thresholds, Well Capitalized	811,914	771,847
Tier 1 Capital to Risk-weighted Assets, Amount
Actual	1,012,050	941,323
Prompt Corrective Action Thresholds, Adequate Capital	487,148	463,108
Prompt Corrective Action Thresholds, Well Capitalized	649,531	617,477
Common Equity Tier One Capital to Risk-weighted Assets, Amount
Actual	1,012,050	941,323
Prompt Corrective Action Thresholds, Adequate Capital	365,361	347,331
Prompt Corrective Action Thresholds, Well Capitalized	527,744	501,700
Tier I Capital to Average Assets, Amount
Actual	1,012,050	941,323
Prompt Corrective Action Thresholds, Adequate Capital	378,397	347,794
Prompt Corrective Action Thresholds, Well Capitalized	$ 472,996	$ 434,742
Risk Based Ratios
Total Capital to Risk-weighted Assets, Actual Ratio	13.46%	13.17%
Total Capital to Risk-weighted Assets, Prompt Corrective Action Thresholds, Adequate Capital Ratio	8.00%	8.00%
Total Capital to Risk-weighted Assets, Prompt Corrective Action Thresholds, Well Capitalized Ratio	10.00%	10.00%
Tier 1 Capital to Risk-Weighted Assets	12.47%	12.20%
Tier I Capital to Risk-weighted Assets, Prompt Corrective Action Thresholds, Adequate Capital Ratio	6.00%	6.00%
Tier I Capital to Risk-weighted Assets, Prompt Corrective Action Thresholds, Well Capitalized Ratio	8.00%	8.00%
Common Equity Tier 1 Capital Ratio (Regulatory)	12.47%	12.20%
Common Equity Tier 1 Capital to Risk-weighted Assets, Prompt Corrective Action Thresholds, Adequately Capitalized Ratio	4.50%	4.50%
Common Equity Tier 1 Capital to Risk-weighted Assets, Prompt Corrective Action Thresholds, Well Capitalized Ratio	6.50%	6.50%
Leverage Ratios
Tier 1 Capital to Average Assets	10.70%	10.83%
Tier I Capital to Average Assets, Prompt Corrective Action Thresholds, Adequate Capital Ratio	4.00%	4.00%
Tier I Capital to Average Assets, Prompt Corrective Action Thresholds, Well Capitalized Ratio	5.00%	5.00%

Regulatory Capital and Divide_4

Regulatory Capital and Dividends - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 09, 2016
Banking and Thrift [Abstract]
Dividends available	$ 192,712,000
Dividend reinvestment and stock purchase plan, stockholder's maximum amount of cash payments per quarter in purchase of common stock	$ 2,500
Stock repurchase program		$ 15,000,000

Loan Servicing (Details)

Loan Servicing (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Banking and Thrift [Abstract]
Unpaid balance of loans serviced for others	$ 533,386	$ 549,618	$ 369,592

Share-Based Compensation - Narr

Share-Based Compensation - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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		$ 3,592,000	$ 2,827,000	$ 2,600,000
Estimated pre-vesting forfeiture rate (as a percent)		2.20%
Income tax benefit related to adoption of ASU 2016-09		$ 644,000	935,000
Aggregate intrinsic value of stock options exercised		1,685,000	1,728,000
Stock options exercised		1,598,000	$ 2,398,000	$ 2,602,000
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%
Unrecognized compensation expense	$ 0	$ 0
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
RSAs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested period		3 years
Unrecognized compensation expense	7,031,000	$ 7,031,000
Unrecognized compensation expense expected recognition period		1 year 5 months
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	0	$ 0
Grant date fair value of ESPP options	$ 21,000

Share-Based Compensation - Comp

Share-Based Compensation - Components of Awards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax compensation expense	$ 3,592	$ 2,827	$ 2,600
Income tax expense (benefit)	(1,276)	(1,883)	(865)
Total share-based compensation expense, net of income taxes	2,316	944	1,735
Stock and ESPP Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax compensation expense	109	121	76
Income tax expense (benefit)	(97)	(322)	18
Total share-based compensation expense, net of income taxes	12	(201)	94
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax compensation expense	3,483	2,706	2,524
Income tax expense (benefit)	(1,179)	(1,561)	(883)
Total share-based compensation expense, net of income taxes	$ 2,304	$ 1,145	$ 1,641

Share-Based Compensation - Stoc

Share-Based Compensation - Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Number of Shares
Beginning balance (in shares)	152,652
Exercised (in shares)	(76,152)
Canceled (in shares)	(200)
Ending balance (in shares)	76,300	152,652
Vested and Expected to Vest, Number of Shares	76,300
Exercisable, Number of Shares	76,300
Weighted-Average Exercise Price
Beginning balance (in dollars per share)	$ 16.71	$ 19.26
Exercised (in dollars per share)	20.99
Canceled (in dollars per share)	28.25
Ending balance (in dollars per share)	12.40	$ 16.71
Vested and Expected to Vest, Weighted-Average Exercise Price (in dollars per share)	12.40
Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 12.40
Weighted Average Remaining Contractual Term
Outstanding	2 years 10 months 10 days
Vested and Expected to Vest	2 years 10 months 10 days
Exercisable	2 years 10 months 10 days
Aggregate Intrinsic Value
Outstanding	$ 1,668,871
Vested and Expected to Vest	1,668,871
Exercisable	$ 1,668,871

Share-Based Compensation - Unve

Share-Based Compensation - Unvested RSAs Outstanding (Details) - RSAs	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Number of Shares
Unvested RSAs, Beginning Balance (in shares) | shares	366,993
Granted (in shares) | shares	105,100
Forfeited (in shares) | shares	(15,198)
Vested (in shares) | shares	(112,533)
Unvested RSAs, Ending Balance (in shares) | shares	344,362
Weighted-Average Grant Date Fair Value
Unvested RSAs, Beginning Balance (in dollars per share) | $ / shares	$ 29.79
Granted (in dollars per share) | $ / shares	48.11
Forfeited (in dollars per share) | $ / shares	42
Vested (in dollars per share) | $ / shares	23.84
Unvested RSAs, Ending Balance (in dollars per share) | $ / shares	$ 36.80

Pension and Other Post Retire_3

Pension and Other Post Retirement Benefit Plans - Narrative (Details) - USD ($)	Mar. 01, 2005	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Percentage of employees covered by plan		13.00%
Minimum participant attained age	55 years
Requisite service period (at least)	10 years
Release of benefit obligation for plan settlement			$ 4,600,000
Settlement charge			(3,803,000)
Settlement loss recognized			761,000
Accumulated benefit obligation		73,193,000	82,157,000
Minimum required contribution in next fiscal year		$ 0
Requisite service period		1000 hours
Employer percentage contribution		2.00%
Vesting period		5 years
Expense recognized in the period		$ 5,114,000	3,691,000	$ 3,441,000
Percentage of the premiums paid by plan participants		100.00%
Curtailment gain				2,157,000
Post retirement plan expense			(301,000)	(2,437,000)
Fair value of plan assets		$ 76,736,000	85,213,000	83,557,000
Net periodic pension benefit cost		(1,693,000)	654,000	509,000
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		71,277,000	78,280,000
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 5,459,000	$ 6,933,000
Contribution for first 3%
Defined Benefit Plan Disclosure [Line Items]
Amount of discretionary contributions made by employer to defined contribution plan, percent		100.00%
Maximum annual contribution percentage per employee		3.00%
Contribution after first 3%
Defined Benefit Plan Disclosure [Line Items]
Amount of discretionary contributions made by employer to defined contribution plan, percent		50.00%
Maximum annual contribution percentage per employee		3.00%
Minimum
Defined Benefit Plan Disclosure [Line Items]
Age of plan participants		55 years
Minimum | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Maturities of debt securities		15 days	15 days
Maximum
Defined Benefit Plan Disclosure [Line Items]
Age of plan participants		65 years
Maximum | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Maturities of debt securities		8 years 2 months 25 days	8 years 10 months
Weighted Average | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Maturities of debt securities		4 years 3 months 15 days	4 years 6 months 12 days
Non-qualified plans
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension benefit cost		$ 161,000	$ 213,000	$ 217,000

Pension and Other Post Retire_4

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 ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in Benefit Obligation:
Benefit obligation at beginning of year	$ 82,157	$ 84,090
Service cost	8	10	$ 9
Interest cost	2,816	3,353	3,273
Actuarial (gain) loss	(6,129)	3,686
Benefits paid	(5,659)	(5,179)
Plan settlements		(3,803)
Benefit obligation at end of year	73,193	82,157	84,090
Change in Plan Assets:
Fair value of plan assets at beginning of year	85,213	83,557
Actual return on plan assets	(3,427)	9,968
Employer contributions	609	670
Benefits paid	(5,659)	(5,179)
Plan settlements		(3,803)
End of year	76,736	85,213	$ 83,557
Funded status at end of year	3,543	3,056
Assets and Liabilities Recognized in the Balance Sheets:
Deferred tax asset	3,855	3,474
Assets	7,024	7,660
Liabilities	3,481	4,604
Amounts Recognized in Accumulated Other Comprehensive Income Not Yet Recognized as Components of Net Periodic Cost, net of tax, consist of:
Accumulated loss	(14,111)	(10,360)
Prior service cost	(409)	(393)
Total	$ (14,520)	$ (10,753)

Pension and Other Post Retire_5

Pension and Other Post Retirement Benefit Plans - Schedule of Accumulated Benefit Obligation in Excess of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Retirement Benefits [Abstract]
Projected benefit obligation	$ 3,481	$ 4,604
Accumulated benefit obligation	3,481	4,604
Fair value of plan assets	$ 0	$ 0

Pension and Other Post Retire_6

Pension and Other Post Retirement Benefit Plans - Schedule of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Service cost	$ 8	$ 10	$ 9
Interest cost	2,816	3,353	3,273
Expected return on plan assets	(4,891)	(4,778)	(4,508)
Amortization of prior service cost	87	90	79
Amortization of net loss	287	1,218	1,656
Settlement loss recognized		761
Net periodic pension benefit cost	$ (1,693)	$ 654	$ 509

Pension and Other Post Retire_7

Pension and Other Post Retirement Benefit Plans - Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Net periodic pension benefit cost	$ (1,693)	$ 654	$ 509
Amortization of net loss	(2,189)	1,504	(228)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Amortization Cost (Credit), before Tax	287	1,979	1,656
Amortization of prior service cost	87	90	79
Total recognized in other comprehensive income (loss)	(1,815)	3,573	1,507
Total recognized in net periodic pension benefit cost and other comprehensive income (loss)	$ (122)	$ 2,919	$ 998

Pension and Other Post Retire_8

Pension and Other Post Retirement Benefit Plans - Amount To Be Amortized From Accumulated Other Comprehensive Income, Next Fiscal Year (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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	$ (432)	$ (830)	$ (1,208)
Amortization of prior service cost	(87)	(87)	(90)
Total	$ (519)	$ (917)	$ (1,298)

Pension and Other Post Retire_9

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted-average Assumptions Used to Determine Benefit Obligation:
Discount rate	4.30%	3.60%	4.20%
Rate of compensation increase for accruing active participants			3.00%
Weighted-average Assumptions Used to Determine Cost:
Discount rate	3.60%	4.20%	4.50%
Expected return on plan assets	6.00%	6.00%	6.00%
Rate of compensation increase for accruing active participants			3.00%

Pension and Other Post Retir_10

Pension and Other Post Retirement Benefit Plans - Schedule of Expected Future Benefit Payments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Retirement Benefits [Abstract]
2,019	$ 5,583
2,020	5,549
2,021	5,429
2,022	5,363
2,023	5,269
After 2,023	24,586
Total	$ 51,779

Pension and Other Post Retir_11

Pension and Other Post Retirement Benefit Plans - Schedule of Plan Assets by Category (Details)	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Actual (as a percent)	100.00%	100.00%
Target (as a percent)	100.00%	100.00%
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Actual (as a percent)	3.90%	6.00%
Target (as a percent)	3.00%	3.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Actual (as a percent)	48.40%	52.40%
Target (as a percent)	50.00%	55.00%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Actual (as a percent)	45.60%	39.60%
Target (as a percent)	45.00%	40.00%
Alternative investments
Defined Benefit Plan Disclosure [Line Items]
Actual (as a percent)	2.10%	2.00%
Target (as a percent)	2.00%	2.00%

Pension and Other Post Retir_12

Pension and Other Post Retirement Benefit Plans - Schedule of Plan Assets by Level (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 76,736	$ 85,213	$ 83,557
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	71,277	78,280
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash & Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,026	5,123
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	16,691	14,598
Quoted Prices in Active Markets for Identical Assets (Level 1) | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,073	2,545
Quoted Prices in Active Markets for Identical Assets (Level 1) | Taxable Bond
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	12,817	12,198
Quoted Prices in Active Markets for Identical Assets (Level 1) | Large Cap Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	18,269	22,137
Quoted Prices in Active Markets for Identical Assets (Level 1) | Mid Cap Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	8,735	10,676
Quoted Prices in Active Markets for Identical Assets (Level 1) | Small Cap Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,713	5,264
Quoted Prices in Active Markets for Identical Assets (Level 1) | International Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,336	4,030
Quoted Prices in Active Markets for Identical Assets (Level 1) | Specialty Alternative Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,617	1,709
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	5,459	6,933
Significant Other Observable Inputs (Level 2) | Government Agency and Municipal Bonds and Notes
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,479	5,679
Significant Other Observable Inputs (Level 2) | Certificates of Deposit
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	980	1,254
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets
Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	76,736	85,213
Fair Value | Cash & Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,026	5,123
Fair Value | Corporate Bonds and Notes
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	16,691	14,598
Fair Value | Government Agency and Municipal Bonds and Notes
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,479	5,679
Fair Value | Certificates of Deposit
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	980	1,254
Fair Value | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,073	2,545
Fair Value | Taxable Bond
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	12,817	12,198
Fair Value | Large Cap Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	18,269	22,137
Fair Value | Mid Cap Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	8,735	10,676
Fair Value | Small Cap Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,713	5,264
Fair Value | International Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,336	4,030
Fair Value | Specialty Alternative Equity
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 1,617	$ 1,709

Income Tax - Reconciliation of

Income Tax - Reconciliation of Federal Statutory to Actual Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Federal statutory income tax rate									21.00%	35.00%	35.00%
Federal Statutory Income Tax at 21% for 2018 and 35% for 2017 and 2016									$ 39,509	$ 46,758	$ 38,031
Tax-exempt Interest Income									(8,347)	(11,127)	(8,749)
Stock Compensation									(622)	(893)	(61)
Earnings on Life Insurance									(868)	(2,302)	(1,486)
Tax Credits									(615)	(811)	(564)
Tax Cuts and Jobs Act - Rate Reform Impact										5,120
Other									(58)	779	438
Income Tax Expense	$ 5,949	$ 8,478	$ 7,961	$ 6,611	$ 15,210	$ 7,939	$ 7,207	$ 7,168	$ 28,999	$ 37,524	$ 27,609
Effective Tax Rate									15.40%	28.10%	25.40%

Income Tax - Components of Inco

Income Tax - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Currently Payable:
Federal									$ 23,633	$ 22,001	$ 18,998
State									1,842
Deferred:
Federal									6,723	9,969	8,233
Tax Cuts and Jobs Act - Rate Reform Impact										5,120
State									(3,199)	434	378
Income Tax Expense	$ 5,949	$ 8,478	$ 7,961	$ 6,611	$ 15,210	$ 7,939	$ 7,207	$ 7,168	$ 28,999	$ 37,524	$ 27,609

Income Tax - Deferred Tax Asset

Income Tax - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Assets:
Differences in Accounting for Loan Losses	$ 19,785	$ 19,526
Differences in Accounting for Loan Fees	749	1,458
Differences in Accounting for Loans and Securities	710	3,681
Deferred Compensation	2,101	4,448
Federal & State Income Tax Loss Carryforward and Credits	6,954	10,829
Net Unrealized Loss on Securities Available for Sale	1,686
Other	2,028	365
Total Assets	34,013	40,307
Liabilities:
Differences in Depreciation Methods	6,496	5,245
Difference in Accounting for Pensions and Other Employee Benefits	566	823
State Income Tax	791	58
Net Unrealized Gain on Securities Available for Sale		2,898
Gain on FDIC Modified Whole Bank Transaction	487	602
Other	4,271	3,897
Total Liabilities	12,611	13,523
Net Deferred Tax Asset Before Valuation Allowance	21,402	26,784
Valuation allowance:
Beginning Balance	(6,966)	(9,815)
Decrease/(Increase) During the Year	6,966	2,849
Ending Balance	0	(6,966)
Net Deferred Tax Asset	$ 21,402	$ 19,818

Income Tax - Narrative (Details

Income Tax - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Valuation Allowance [Line Items]
Increase in deferred tax assets	$ 1,584,000
Release of deferred tax asset	6,966,000	$ 2,849,000
Net Unrealized Loss on Securities Available for Sale	4,584,000
Decrease in deferred tax assets for federal and state net operating loss carryforwards	3,875,000
Decrease in deferred tax assets for loans	2,971,000
Deferred compensation	2,347,000
Additional paid-in capital	840,052,000	$ 834,870,000
Unrecorded deferred tax liability	5,308,000
CFS
Valuation Allowance [Line Items]
Additional paid-in capital	13,393,000
Ameriana
Valuation Allowance [Line Items]
Additional paid-in capital	11,883,000
State and Local Jurisdiction
Valuation Allowance [Line Items]
Release of deferred tax asset	6,966,000
State tax loss carryforward	31,183,000
State deferred tax assets	$ 3,767,000

Net Income Per Share - Reconcil

Net Income Per Share - Reconciliation of Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income available to common stockholders									$ 159,139	$ 96,070	$ 81,051
Net income available to common stockholders									$ 159,139	$ 96,070	$ 81,051
Weighted-Average Shares
Net income available to common stockholders (in shares)	49,314,276	49,286,945	49,252,580	49,192,647	49,144,310	48,431,880	42,038,824	40,984,481	49,262,015	45,181,221	40,767,343
Effect of dilutive stock options and warrants (in shares)									208,908	221,757	245,790
Net income available to common stockholders (in shares)	49,511,233	49,492,019	49,451,406	49,427,972	49,379,303	48,643,774	42,243,539	41,220,586	49,470,923	45,402,978	41,013,133
Basic net income per share:
Net income available to common stockholders (in dollars per share)	$ 0.85	$ 0.83	$ 0.80	$ 0.75	$ 0.49	$ 0.50	$ 0.57	$ 0.57	$ 3.23	$ 2.13	$ 1.99
Diluted net income per share:
Net income available to common stockholders (in dollars per share)	$ 0.85	$ 0.83	$ 0.80	$ 0.74	$ 0.49	$ 0.50	$ 0.57	$ 0.56	$ 3.22	$ 2.12	$ 1.98

Net Income Per Share - Narrativ

Net Income Per Share - Narrative (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Stock options not included in the earnings per share calculation (in shares)	0	0	51,949
Weighted average exercise price (in dollars per share)	$ 12.40	$ 16.71	$ 19.26

Quarterly Results of Operatio_3

Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 108,653	$ 104,800	$ 100,871	$ 93,620	$ 90,348	$ 84,847	$ 71,467	$ 68,234	$ 407,944	$ 314,896	$ 253,312
Interest expense	20,769	18,314	16,300	13,704	11,583	10,427	8,367	7,235	69,087	37,612	26,839
NET INTEREST INCOME	87,884	86,486	84,571	79,916	78,765	74,420	63,100	60,999	338,857	277,284	226,473
Provision for loan losses	1,664	1,400	1,663	2,500	1,800	2,083	2,875	2,385	7,227	9,143	5,657
NET INTEREST INCOME AFTER PROVISION FOR LOAN LOSSES	86,220	85,086	82,908	77,416	76,965	72,337	60,225	58,614	331,630	268,141	220,816
Non-interest income	19,180	19,527	18,191	19,561	19,061	18,668	18,434	14,846	76,459	71,009	65,203
Non-interest expense	57,738	55,022	53,504	53,687	56,433	58,708	47,316	43,099	219,951	205,556	177,359
INCOME BEFORE INCOME TAX	47,662	49,591	47,595	43,290	39,593	32,297	31,343	30,361
Income tax expense	5,949	8,478	7,961	6,611	15,210	7,939	7,207	7,168	28,999	37,524	27,609
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 41,713	$ 41,113	$ 39,634	$ 36,679	$ 24,383	$ 24,358	$ 24,136	$ 23,193	$ 159,139	$ 96,070	$ 81,051
Basic EPS (in dollars per share)	$ 0.85	$ 0.83	$ 0.80	$ 0.75	$ 0.49	$ 0.50	$ 0.57	$ 0.57	$ 3.23	$ 2.13	$ 1.99
Diluted EPS (in dollars per share)	$ 0.85	$ 0.83	$ 0.80	$ 0.74	$ 0.49	$ 0.50	$ 0.57	$ 0.56	$ 3.22	$ 2.12	$ 1.98
Average Shares Outstanding:
Basic (in shares)	49,314,276	49,286,945	49,252,580	49,192,647	49,144,310	48,431,880	42,038,824	40,984,481	49,262,015	45,181,221	40,767,343
Diluted (in shares)	49,511,233	49,492,019	49,451,406	49,427,972	49,379,303	48,643,774	42,243,539	41,220,586	49,470,923	45,402,978	41,013,133

Condensed Financial Informati_3

Condensed Financial Information (parent company only) - Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Investment securities	$ 1,142,195	$ 999,947
Premises and equipment	93,420	95,852
Interest receivable	40,881	37,130
Goodwill	445,355	445,355	$ 244,000
Cash surrender value of life insurance	224,939	223,557
Other assets	47,772	42,338
TOTAL ASSETS	9,884,716	9,367,478
Liabilities
Subordinated debentures and term loans	138,463	139,349
Interest payable	5,607	4,390
Other liabilities	45,295	52,708
Total Liabilities	8,476,456	8,064,015
Stockholders' equity	1,408,260	1,303,463	$ 901,657	$ 850,509
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	9,884,716	9,367,478
Parent
Assets
Cash	87,435	31,527
Investment in subsidiaries	1,459,036	1,411,360
Investment securities		31
Premises and equipment	1,158	1,252
Interest receivable	6	5
Goodwill	448	448
Cash surrender value of life insurance	810	787
Other assets	5,240	3,480
TOTAL ASSETS	1,554,133	1,448,890
Liabilities
Subordinated debentures and term loans	138,463	138,241
Interest payable	994	968
Other liabilities	6,416	6,218
Total Liabilities	145,873	145,427
Stockholders' equity	1,408,260	1,303,463
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 1,554,133	$ 1,448,890

Condensed Financial Informati_4

Condensed Financial Information (parent company only) - Statement of Income and Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income
Other income									$ 5,192	$ 2,970	$ 3,594
Expenses
Interest expense	$ 20,769	$ 18,314	$ 16,300	$ 13,704	$ 11,583	$ 10,427	$ 8,367	$ 7,235	69,087	37,612	26,839
Salaries and employee benefits									131,704	119,812	102,552
Other expenses									16,966	15,543	15,470
INCOME BEFORE INCOME TAX	47,662	49,591	47,595	43,290	39,593	32,297	31,343	30,361
Income tax benefit	(5,949)	(8,478)	(7,961)	(6,611)	(15,210)	(7,939)	(7,207)	(7,168)	(28,999)	(37,524)	(27,609)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS									159,139	96,070	81,051
Net income	$ 41,713	$ 41,113	$ 39,634	$ 36,679	$ 24,383	$ 24,358	$ 24,136	$ 23,193	159,139	96,070	81,051
Other comprehensive income (loss)									(17,888)	10,673	(12,219)
Comprehensive income									141,251	106,743	68,832
Parent
Income
Dividends from subsidiaries									100,954	33,014	33,546
Loss on sale of available for sale securities										(50)
Other income									572	350	143
Total income									101,526	33,314	33,689
Expenses
Interest expense									8,233	7,572	7,185
Salaries and employee benefits									3,729	4,118	639
Net occupancy and equipment expenses									851	797	832
Other outside services									489	1,810	967
Professional services									270	442	279
Other expenses									442	(385)	(470)
Total expenses									14,014	14,354	9,432
INCOME BEFORE INCOME TAX									87,512	18,960	24,257
Income tax benefit									3,298	5,946	3,243
Income before equity in undistributed income of subsidiaries									90,810	24,906	27,500
Equity in undistributed income of subsidiaries									68,329	71,164	53,551
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS									159,139	96,070	81,051
Net income									159,139	96,070	81,051
Other comprehensive income (loss)									(17,888)	10,673	(12,219)
Comprehensive income									$ 141,251	$ 106,743	$ 68,832

Condensed Financial Informati_5

Condensed Financial Information (parent company only) - Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flow From Operating Activities:
Net income	$ 41,713	$ 41,113	$ 39,634	$ 36,679	$ 24,383	$ 24,358	$ 24,136	$ 23,193	$ 159,139	$ 96,070	$ 81,051
Adjustments to Reconcile Net Income to Net Cash:
Share-based compensation									3,592	2,827	2,600
Net Change in:
Net cash provided by operating activities									180,235	126,502	103,719
Cash Flows from Investing Activities:
Purchase of securities available for sale									(370,284)	(479,045)	(281,470)
Net cash received in acquisition										54,536
Other									804	(4,047)	(4,490)
Net cash used in investing activities									(575,576)	(635,330)	(448,704)
Cash Flows from Financing Activities:
Stock issued under employee benefit plans									707	519	462
Stock issued under dividend reinvestment and stock purchase plan									1,211	991	835
Stock options exercised									1,598	2,398	2,602
Stock redeemed									(1,902)	(1,283)	(1,980)
Net cash provided by financing activities									379,683	535,806	370,742
Cash and Cash Equivalents, beginning of the year				154,905				127,927	154,905	127,927	102,170
Cash and Cash Equivalents, end of year	139,247				154,905				139,247	154,905	127,927
Parent
Cash Flow From Operating Activities:
Net income									159,139	96,070	81,051
Adjustments to Reconcile Net Income to Net Cash:
Share-based compensation									1,256	1,215	1,166
Distributions in excess of (equity in undistributed) income of subsidiaries									(68,329)	(71,164)	(53,551)
Loss on sale of available for sale securities										50
Net Change in:
Other assets									584	3,358	833
Other liabilities									274	(1,900)	849
Investment in subsidiaries - operating activities									841	1,112	(1,938)
Net cash provided by operating activities									93,765	28,741	28,410
Cash Flows from Investing Activities:
Purchase of securities available for sale											(19,804)
Net cash received in acquisition										37
Other									2,189
Net cash used in investing activities									2,189	37	(19,804)
Cash Flows from Financing Activities:
Cash dividends									(41,660)	(31,820)	(22,203)
Stock issued under employee benefit plans									707	519	462
Stock issued under dividend reinvestment and stock purchase plan									1,211	991	835
Stock options exercised									1,598	2,398	2,602
Stock redeemed									(1,902)	(1,283)	(1,980)
Net cash provided by financing activities									(40,046)	(29,195)	(20,284)
Cash and Cash Equivalents, beginning of the year				$ 31,527				$ 31,944	31,527	31,944	43,622
Cash and Cash Equivalents, end of year	$ 87,435				$ 31,527				$ 87,435	$ 31,527	$ 31,944

Accounting Matters (Details)

Accounting Matters (Details) - Forecast - ASU 2016-02 $ in Millions	Jan. 01, 2019USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset	$ 23.3
Lease liability	$ 23.8

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 09, 2018	Dec. 31, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Share price (in dollars per share)	$ 45.71
Assets		$ 9,884,716	$ 9,367,478
MBT
Subsequent Event [Line Items]
Estimated transaction value	$ 290,900
Assets		$ 1,300,000