First Financial Bancorp. (FFBC) 10-Q 7 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	9 Months Ended
	Sep. 30, 2018	Nov. 06, 2018
Document Information [Line Items]
Entity Emerging Growth Company	false
Entity Small Business	false
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	FFBC
Entity Registrant Name	FIRST FINANCIAL BANCORP /OH/
Entity Central Index Key	708,955
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		97,907,701

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
ASSETS
Cash and due from banks	$ 193,288	$ 150,650
Interest-bearing deposits with other banks	28,989	33,974
Investment securities available-for-sale, at fair value (amortized cost $2,662,329 at September 30, 2018 and $1,348,227 at December 31, 2017)	2,626,726	1,349,408
Investment securities held-to-maturity (fair value $422,638 at September 30, 2018 and $653,101 at December 31, 2017)	434,369	654,008
Other investments	115,757	53,140
Loans held for sale	13,277	11,502
Loans
Commercial	2,426,590	1,912,743
Lease financing	95,317	89,347
Real estate - construction	565,077	467,730
Real estate-commercial	3,868,143	2,490,091
Real estate-residential	932,962	471,391
Home equity	816,133	493,604
Installment	97,413	41,586
Credit card	45,741	46,691
Total loans and leases	8,847,376	6,013,183
Allowance for loan and lease losses	57,715	54,021
Net loans and leases	8,789,661	5,959,162
Premises and equipment	219,940	125,036
Goodwill and other intangibles	934,360	209,379
Accrued interest and other assets	486,300	350,664
Total assets	13,842,667	8,896,923
Deposits
Interest-bearing	2,284,271	1,453,463
Savings	3,134,944	2,462,420
Time	1,957,574	1,317,105
Total interest-bearing deposits	7,376,789	5,232,988
Noninterest-bearing	2,375,845	1,662,058
Total deposits	9,752,634	6,895,046
Federal funds purchased	123,452	72,265
FHLB short-term borrowings	1,170,800	742,300
Total short-term borrowings	1,294,252	814,565
Long-term debt	570,037	119,654
Total borrowed funds	1,864,289	934,219
Accrued interest and other liabilities	190,224	136,994
Total liabilities	11,807,147	7,966,259
SHAREHOLDERS' EQUITY
Common stock - no par value Authorized - 160,000,000 shares Issued - 104,281,794 shares in 2018 and 68,730,731 shares in 2017	1,633,828	573,109
Retained earnings	564,545	491,847
Accumulated other comprehensive loss	(52,897)	(20,390)
Treasury stock, at cost, 6,367,268 shares in 2018 and 6,661,644 shares in 2017	(109,956)	(113,902)
Total shareholders' equity	2,035,520	930,664
Total liabilities and shareholders' equity	$ 13,842,667	$ 8,896,923

CONSOLIDATED BALANCE SHEETS CON

CONSOLIDATED BALANCE SHEETS CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Available-for-sale Securities, Amortized Cost Basis	$ 2,662,329	$ 1,348,227
Debt Securities, Held-to-maturity, Fair Value	$ 422,638	$ 653,101
Common Stock, No Par Value	$ 0	$ 0
Common Stock, Shares Authorized	160,000,000	160,000,000
Common Stock, Shares, Issued	104,281,794	68,730,731
Treasury Stock, Shares	6,367,268	6,661,644

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest income
Loans, including fees	$ 123,397	$ 71,148	$ 320,607	$ 205,764
Investment securities
Taxable	21,801	13,150	56,315	37,356
Tax-exempt	3,807	1,537	9,532	4,347
Total interest on investment securities	25,608	14,687	65,847	41,703
Other earning assets	215	(917)	499	(2,932)
Total interest income	149,220	84,918	386,953	244,535
Interest expense
Deposits	14,672	10,335	39,764	25,939
Short-term borrowings	6,052	2,566	12,847	6,049
Long-term borrowings	5,011	1,538	11,066	4,616
Total interest expense	25,735	14,439	63,677	36,604
Net interest income	123,485	70,479	323,276	207,931
Provision for loan and lease losses	3,238	2,953	9,276	3,787
Net interest income after provision for loan and lease losses	120,247	67,526	314,000	204,144
Noninterest income
Service Charges on Deposit Accounts	10,316	5,169	24,923	14,585
Trust and wealth management fees	3,728	3,324	11,379	10,476
Bankcard income	5,261	3,272	13,998	9,908
Client derivative fees	3,029	1,779	6,249	4,371
Net gain from sales of loans	1,739	1,455	4,643	3,998
Net gain (loss) on sales of investment securities	(167)	276	(197)	1,630
Other	4,778	7,667	12,883	12,792
Total noninterest income	28,684	22,942	73,878	57,760
Noninterest expenses
Salaries and employee benefits	50,852	33,827	137,485	97,121
Net occupancy	6,765	4,328	17,893	13,145
Furniture and equipment	4,072	2,161	11,410	6,474
Data processing	4,502	3,455	22,478	10,254
Marketing	2,502	649	5,947	2,141
Communication	785	430	2,362	1,345
Professional services	2,621	2,030	10,478	5,257
State intangible tax	1,223	721	3,066	2,163
FDIC assessments	734	1,051	2,951	3,001
Loss (gain) - other real estate owned	538	237	332	423
Other	10,821	5,554	26,056	15,720
Total noninterest expenses	85,415	54,443	240,458	157,044
Income before income taxes	63,516	36,025	147,420	104,860
Income tax expense	12,859	11,199	29,839	32,884
Net income	$ 50,657	$ 24,826	$ 117,581	$ 71,976
Earnings per common share
Basic	$ 0.52	$ 0.40	$ 1.37	$ 1.17
Diluted	0.51	0.40	1.36	1.16
Cash dividends declared per share	$ 0.20	$ 0.17	$ 0.58	$ 0.51
Average common shares outstanding - basic	97,411,201	61,577,619	85,602,116	61,507,160
Average common shares outstanding - diluted	98,484,228	62,189,637	86,639,927	62,185,874

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 50,657	$ 24,826	$ 117,581	$ 71,976
Other comprehensive (loss) income, net of tax
Unrealized gain (loss) on debt securities arising during the period	(10,185)	1,501	(28,993)	7,064
Change in retirement obligation	347	213	1,164	615
Unrealized gain (loss) on derivatives	99	129	414	385
Other comprehensive income (loss)	(9,739)	1,843	(27,415)	8,064
Comprehensive income	$ 40,918	$ 26,669	$ 90,166	$ 80,040

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock
Beginning Balances (in shares) at Dec. 31, 2016		68,730,731			(6,751,179)
Beginning Balances at Dec. 31, 2016	$ 865,224	$ 570,382	$ 437,188	$ (28,443)	$ (113,903)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	71,976		71,976
Other comprehensive income (loss)	8,064			8,064
Cash dividends declared :
Common stock at $0.58 per share in 2018 and $0.51 per share in 2017	(31,576)		(31,576)
Stock Issued During Period, Shares, Other					4,848
Adjustments to Additional Paid in Capital, Other	0	(82)			$ 82
Exercise of stock options, net of shares purchased (in shares)					53,303
Exercise of stock options, net of shares purchased	18	(885)			$ 903
Restricted stock awards, net of forfeitures (in shares)					23,762
Restricted stock awards, net of forfeitures	(2,783)	(1,696)			$ (1,087)
Share-based compensation expense	4,031	$ 4,031
Ending Balances (in shares) at Sep. 30, 2017		68,730,731			(6,669,266)
Ending Balances at Sep. 30, 2017	914,954	$ 571,750	477,588	(20,379)	$ (114,005)
Beginning Balances (in shares) at Dec. 31, 2017		68,730,731			(6,661,644)
Beginning Balances at Dec. 31, 2017	930,664	$ 573,109	491,847	(20,390)	$ (113,902)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	0		5,092	(5,092)
Net income	117,581		117,581
Other comprehensive income (loss)	(27,415)			(27,415)
Cash dividends declared :
Common stock at $0.58 per share in 2018 and $0.51 per share in 2017	(49,975)		(49,975)
Stock Issued During Period, Shares, New Issues		35,551,063
Stock Issued During Period, Value, Acquisitions	1,045,876	$ 1,045,876
Stock Options and Warrants Acquired And Converted Pursuant To Acquisition	16,037	16,037
Stock Issued During Period, Shares, Other					57,530
Adjustments to Additional Paid in Capital, Other	0	(984)			$ 984
Exercise of stock options, net of shares purchased (in shares)					32,941
Exercise of stock options, net of shares purchased	284	(282)			$ 566
Restricted stock awards, net of forfeitures (in shares)					203,905
Restricted stock awards, net of forfeitures	(2,517)	(4,913)			$ 2,396
Share-based compensation expense	4,985	$ 4,985
Ending Balances (in shares) at Sep. 30, 2018		104,281,794			(6,367,268)
Ending Balances at Sep. 30, 2018	$ 2,035,520	$ 1,633,828	$ 564,545	$ (52,897)	$ (109,956)

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS EQUITY (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Common Stock, Dividends, Per Share, Declared	$ 0.20	$ 0.17	$ 0.58	$ 0.51

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities
Net income	$ 117,581	$ 71,976
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses	9,276	3,787
Depreciation and amortization	17,326	9,504
Stock-based compensation expense	4,985	4,031
Pension expense (income)	521	(956)
Net amortization (accretion) on investment securities	8,209	7,916
Net (gain) loss on sales of investment securities	197	(1,630)
Originations of loans held for sale	(113,142)	(123,387)
Net gains from sales of loans held for sale	(4,643)	(3,998)
Proceeds from sales of loans held for sale	112,904	123,415
Deferred income taxes	(349)	3,977
Decrease (increase) cash surrender value of life insurance	4,484	563
Decrease (increase) in interest receivable	(4,264)	(4,069)
Decrease (increase) in indemnification asset	(1,900)	(3,840)
(Decrease) increase in interest payable	3,597	(1,052)
Decrease (increase) in other assets	(25)	1,247
(Decrease) increase in other liabilities	24,990	(1,046)
Net cash provided by (used in) operating activities	174,579	92,992
Investing activities
Proceeds from sales of securities available-for-sale	259,518	179,517
Proceeds from calls, paydowns and maturities of securities available-for-sale	271,597	158,454
Purchases of securities available-for-sale	(566,528)	(563,172)
Proceeds from calls, paydowns and maturities of securities held-to-maturity	31,964	98,824
Payments to Acquire Held-to-maturity Securities	14,014	15,465
Net decrease (increase) in interest-bearing deposits with other banks	4,985	47,663
Net decrease (increase) in loans and leases	(45,783)	(230,174)
Proceeds from disposal of other real estate owned	3,138	6,797
Purchases of premises and equipment	(15,544)	(4,798)
Net cash acquired from business combinations	64,941	0
Net cash paid for branch divestitures	(41,197)
Net cash provided by (used in) investing activities	(46,923)	(322,354)
Financing activities
Net (decrease) increase in total deposits	(406,450)	200,302
Net (decrease) increase in short-term borrowings	284,092	55,820
Payments of long-term debt	52,274	94
Proceeds from FHLB borrowings	150,000	0
Cash dividends paid on common stock	(60,670)	(30,708)
Proceeds from exercise of stock options	284	284
Net cash provided by (used in) financing activities	(85,018)	225,604
Cash and due from banks:
Change in cash and due from banks	42,638	(3,758)
Cash and due from banks at beginning of period	150,650	121,598
Cash and due from banks at end of period	193,288	117,840
Supplemental schedule for investing activities
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Assets, Net Of Purchase Consideration	3,341,999	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	4,018,948	0
Goodwill	$ 676,949	$ 0

BASIS OF PRESENTATION

BASIS OF PRESENTATION	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION The Consolidated Financial Statements of First Financial Bancorp., a financial holding company principally serving Ohio, Indiana, Kentucky and Illinois, include the accounts and operations of First Financial and its wholly-owned subsidiary, First Financial Bank. All significant intercompany transactions and accounts have been eliminated in consolidation. Certain reclassifications of prior periods' amounts have been made to conform to current year presentation. Such reclassifications had no effect on net earnings. The preparation of financial statements in conformity with GAAP requires management to make estimates, assumptions and judgments that affect the amounts reported in the Consolidated Financial Statements and accompanying Notes. These estimates, assumptions and judgments are inherently subjective and may be susceptible to significant change. Actual realized amounts could differ materially from these estimates. These interim financial statements have been prepared in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they may not include all of the information and accompanying notes necessary to constitute a complete set of financial statements required by GAAP and should be read in conjunction with the audited consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 . Management believes these unaudited consolidated financial statements reflect all adjustments of a normal recurring nature which are necessary for a fair presentation of the results for the interim periods presented. The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period. The Consolidated Balance Sheet as of December 31, 2017 has been derived from the audited financial statements in the Company’s 2017

RECENTLY ADOPTED AND ISSUED ACC

RECENTLY ADOPTED AND ISSUED ACCOUNTING STANDARDS	9 Months Ended
	Sep. 30, 2018
Recently Adopted and Issued Accounting Standards [Abstract]
Recently Adopted and Issued Accounting Standards Disclosure [Text Block]	RECENTLY ADOPTED AND ISSUED ACCOUNTING STANDARDS In May 2014, the FASB issued an update (ASU 2014-09, Revenue from Contracts with Customers) which outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. Under the revised standard, an entity recognizes 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. The ASU applies to all contracts with customers except those that are within the scope of other topics in the FASB Accounting Standards Codification. Certain of the ASU’s provisions also apply to transfers of nonfinancial assets, including in-substance nonfinancial assets that are not an output of an entity’s ordinary activities, such as sales of property, plant, and equipment; real estate; or intangible assets. The ASU also requires significantly expanded disclosures about revenue recognition. For further detail, see Note 13 – Revenue Recognition. In January 2016, the FASB issued an update (ASU 2016-01, Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities) which requires entities to measure many equity investments at fair value and recognize changes in fair value in net income. This update does not apply to equity investments that result in consolidation, those accounted for under the equity method and certain others, and will eliminate use of the available for sale classification for equity securities while providing a new measurement alternative for equity investments that do not have readily determinable fair values and do not qualify for the net asset value practical expedient. This update also requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes. The guidance in this ASU became effective in the first quarter of 2018 and did not have a material impact on the Consolidated Financial Statements. At adoption, an adjustment was made to move $0.2 million of net unrealized gain on AFS equity securities out of AOCI and into Retained Earnings since changes in fair values are now recognized in net income. Additionally, i n accordance with the guidance, the Company measured the fair value of its financial instruments as of September 30, 2018 using an exit price notion. For further detail, see Note 15 – Fair Value Disclosures. In February 2016, the FASB issued an update (ASU 2016-02, Leases) which requires lessees to record most leases on their balance sheet and recognize leasing expenses in the income statement. Operating leases, except for short-term leases that are subject to an accounting policy election, will be recorded on the balance sheet for lessees by establishing a lease liability and corresponding right-of-use asset. The guidance in this ASU will become effective for interim and annual reporting periods beginning after December 15, 2018, with early adoption permitted. Given operating leases outstanding as of September 30, 2018 , First Financial does not expect this ASU to have a material impact on the income statement, but does anticipate an increase in the Company's assets and liabilities. Decisions to repurchase, modify or renew leases prior to the implementation date will impact this level of materiality. In June 2016, the FASB issued an update (ASU 2016-13, Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments) which significantly changes how entities are required to measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. This update will replace the current incurred loss approach for estimating credit losses with an expected loss model for instruments measured at amortized cost, including loans and leases. Expected credit losses are required to be based on amortized cost and reflect losses expected over the remaining contractual life of the asset. Management is expected to consider any available information relevant to assessing the collectibility of contractual cash flows, such as information about past events, current conditions, voluntary prepayments and reasonable and supportable forecasts, when developing expected credit loss estimates. In addition to the new framework for calculating the ALLL, this update requires allowances for available-for-sale debt securities rather than a reduction of the security's carrying amount under the current other-than-temporary impairment model. This update also simplifies the accounting model for purchased credit-impaired debt securities and loans and will require new and updated footnote disclosures. The guidance in this ASU will become effective for interim and annual reporting periods beginning after December 15, 2019. Early adoption is permitted for all entities for interim and annual reporting periods beginning after December 15, 2018. First Financial has formed an internal management committee and engaged a third party vendor to assist with the transition to the guidance set forth in this update. The committee is currently evaluating the impact of this update on First Financial’s Consolidated Financial Statements. In August 2016, the FASB issued an update (ASU 2016-15 Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments) which may change how an entity classifies certain cash receipts and cash payments on its statement of cash flows to reduce diversity in practice. The update also provides guidance on when an entity should separate cash flows and classify them into more than one class and when an entity should classify the aggregate of those cash flows into a single class based on the predominance principle. The guidance in this ASU became effective in the first quarter of 2018 and did not have a material impact on the Consolidated Financial Statements. In January 2017, the FASB issued an update (ASU 2017-04, Intangibles - Goodwill and Other (Topic 350), Simplifying the Test for Goodwill Impairment) which simplifies the subsequent measurement of goodwill by eliminating Step 2 from goodwill impairment testing. This update requires an entity to perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount, and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, with any loss recognized not to exceed the total amount of goodwill allocated to that reporting unit. Additionally, the update requires consideration of the income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable, and eliminates the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment. First Financial early adopted the provisions set forth in this update in 2017. Adoption of this update did not have a material impact on First Financial's Consolidated Financial Statements. In March 2017, the FASB issued an update (ASU 2017-07, Compensation - Retirement Benefits (Topic 715), Improving the Presentation of the Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost) which requires disaggregation of the service cost component from the other components of net benefit cost. This update also provides explicit guidance on how to present the service cost component and the other components of net benefit cost in the income statement and allows only the service cost component of net benefit cost to be eligible for capitalization. The guidance in this ASU became effective in the first quarter of 2018 and did not have a material impact on the Consolidated Financial Statements. In March 2017, the FASB issued an update (ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20), Premium Amortization on Purchased Callable Debt Securities) which amends the amortization period for certain purchased callable debt securities held at a premium and shortens the amortization period for the premium to the earliest call date rather than as an adjustment of yield over the contractual life of the instrument. This update more closely aligns the amortization period of premiums and discounts to expectations incorporated in market pricing on the underlying securities, as in most cases, market participants price securities to the call date that produces the worst yield when the coupon is above current market rates (that is, the security is trading at a premium) and price securities to maturity when the coupon is below market rates (that is, the security is trading at a discount) in anticipation that the borrower will act in its economic best interest in an attempt to more closely align interest income recorded on bonds held at a premium or a discount with the economics of the underlying instrument. The guidance in this ASU will become effective for reporting periods, beginning after December 15, 2018, with early adoption permitted. First Financial is currently evaluating the impact of this update on its Consolidated Financial Statements. In May 2017, the FASB issued an update (ASU 2017-09, Compensation - Stock Compensation (Topic 718), Scope of Modification Accounting), which provides clarity and reduces the diversity in practice, cost and complexity when accounting for a change to the terms or conditions of a share-based payment award. The amendments in this update provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718 clarifying that an entity will not apply modification accounting to a share-based payment award if the award's fair value (or calculated value or intrinsic value), vesting conditions and classification as an equity or liability instrument are the same immediately before and after the change. The guidance in this ASU became effective in the first quarter of 2018 and did not have a material impact on the Consolidated Financial Statements. In August 2017, the FASB issued an update (ASU 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities) to better align financial reporting for hedging activities with the economic objectives of those activities. This update aligns certain aspects of hedge documentation, effectiveness assessments, accounting and disclosures, and expands permissible hedge strategies as of the date of adoption. The guidance in this ASU will become effective for reporting periods beginning after December 15, 2018, with early adoption permitted, and will require a modified retrospective transition method with recognition of the cumulative effect of the change on the opening balance of each affected component of equity. Amended disclosures will be required prospectively. First Financial is currently evaluating the impact of this update on its Consolidated Financial Statements. In February 2018, the FASB issued an update (ASU 2018-02, Income statement-Reporting Comprehensive Income: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income), which allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. Consequently, the amendments eliminated the stranded tax effects resulting from the Tax Cuts and Jobs Act and will improve the usefulness of information reported to financial statement users. The amendments only relate to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, and the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not effected. The amendments in this update also require certain disclosures about stranded tax effects. The guidance in this ASU will become effective for reporting periods beginning after December 15, 2018, with early adoption permitted, and is applied either in the period of adoption or retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act is recognized. First Financial early adopted the provisions set forth in this update in the first quarter of 2018, and as a result, reclassified $4.9 million

INVESTMENTS

INVESTMENTS	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
INVESTMENTS	INVESTMENTS For the three months ended September 30, 2018, proceeds on the sale of $43.3 million of AFS securities resulted in gains of $0.3 million and losses of $0.4 million . For the three months ended September 30, 2017, proceeds on the sale of $53.9 million of AFS securities resulted in gains of $0.4 million and losses of $0.1 million . For the nine months ended September 30, 2018 , proceeds on the sale of $259.5 million of AFS securities resulted in gains of $0.3 million and losses of $0.5 million . For the nine months ended September 30, 2017 , proceeds on the sale of $179.6 million of AFS securities resulted in gains of $1.8 million and losses of $0.2 million . In addition to the sale of certain securities, First Financial reclassified $367.9 million of HTM securities to AFS to align with post-merger investment strategies during the second quarter 2018. The following is a summary of HTM and AFS investment securities as of September 30, 2018 : Held-to-maturity Available-for-sale (Dollars in thousands) Amortized Unrecognized gain Unrecognized loss Fair Amortized cost Unrealized gain Unrealized loss Fair U.S. Treasuries $ 0 $ 0 $ 0 $ 0 $ 99 $ 0 $ (4 ) $ 95 Securities of U.S. government agencies and corporations 0 0 0 0 33,438 7 (600 ) 32,845 Mortgage-backed securities - residential 26,603 0 (1,615 ) 24,988 581,657 551 (14,262 ) 567,946 Mortgage-backed securities - commercial 150,223 0 (6,378 ) 143,845 362,874 118 (5,646 ) 357,346 Collateralized mortgage obligations 13,182 0 (727 ) 12,455 864,824 940 (15,436 ) 850,328 Obligations of state and other political subdivisions 244,361 275 (3,286 ) 241,350 247,206 1,533 (2,626 ) 246,113 Asset-backed securities 0 0 0 0 490,685 582 (1,499 ) 489,768 Other securities 0 0 0 0 81,546 1,039 (300 ) 82,285 Total $ 434,369 $ 275 $ (12,006 ) $ 422,638 $ 2,662,329 $ 4,770 $ (40,373 ) $ 2,626,726 The following is a summary of held-to-maturity and available-for-sale investment securities as of December 31, 2017 : Held-to-maturity Available-for-sale (Dollars in thousands) Amortized Unrecognized gain Unrecognized Fair Amortized Unrealized Unrealized Fair U.S. Treasuries $ 0 $ 0 $ 0 $ 0 $ 98 $ 0 $ (1 ) $ 97 Securities of U.S. government agencies and corporations 11,168 0 (76 ) 11,092 15,695 220 0 15,915 Mortgage-backed securities - residential 162,093 2,042 (1,535 ) 162,600 290,793 849 (2,599 ) 289,043 Mortgage-backed securities - commercial 255,027 1,372 (3,000 ) 253,399 150,356 164 (1,417 ) 149,103 Collateralized mortgage obligations 143,545 354 (1,602 ) 142,297 306,095 1,158 (1,861 ) 305,392 Obligations of state and other political subdivisions 82,175 1,804 (266 ) 83,713 124,269 2,162 (676 ) 125,755 Asset-backed securities 0 0 0 0 377,655 1,628 (306 ) 378,977 Other securities 0 0 0 0 83,266 2,147 (287 ) 85,126 Total $ 654,008 $ 5,572 $ (6,479 ) $ 653,101 $ 1,348,227 $ 8,328 $ (7,147 ) $ 1,349,408 The following table provides a summary of investment securities by contractual maturity as of September 30, 2018 , except for residential and commercial mortgage-backed securities, collateralized mortgage obligations and asset-backed securities, which are shown as single totals due to the unpredictability of the timing in principal repayments. Held-to-maturity Available-for-sale (Dollars in thousands) Amortized cost Fair value Amortized cost Fair value By Contractual Maturity: Due in one year or less $ 0 $ 0 $ 3,932 $ 3,922 Due after one year through five years 275 277 72,831 72,633 Due after five years through ten years 18,337 18,274 138,584 139,591 Due after ten years 225,749 222,799 146,942 145,192 Mortgage-backed securities - residential 26,603 24,988 581,657 567,946 Mortgage-backed securities - commercial 150,223 143,845 362,874 357,346 Collateralized mortgage obligations 13,182 12,455 864,824 850,328 Asset-backed securities 0 0 490,685 489,768 Total $ 434,369 $ 422,638 $ 2,662,329 $ 2,626,726 Unrealized gains and losses on debt securities are generally due to fluctuations in current market yields relative to the yields of the debt securities at their amortized cost. All securities with unrealized losses are reviewed quarterly to determine if any impairment is considered other than temporary, requiring a write-down to fair value. First Financial considers the percentage loss on a security, duration of the loss, average life or duration of the security, credit rating of the security and payment performance, as well as the Company's intent and ability to hold the security to maturity, when determining whether any impairment is other than temporary. At this time First Financial does not intend to sell, and it is not more likely than not that the Company will be required to sell, debt securities temporarily impaired prior to maturity or recovery of the recorded value. First Financial had no other than temporary impairment related to its investment securities portfolio as of September 30, 2018 or December 31, 2017 . As of September 30, 2018 , the Company's investment securities portfolio consisted of 1,414 securities, of which 909 were in an unrealized loss position. As of December 31, 2017, the Company's investment securities portfolio consisted of 775 securities, of which 237 were in an unrealized loss position. The following tables provide the fair value and gross unrealized losses on investment securities in an unrealized loss position, aggregated by investment category and the length of time the individual securities have been in a continuous loss position: September 30, 2018 Less than 12 months 12 months or more Total (Dollars in thousands) Fair value Unrealized loss Fair Unrealized Fair Unrealized U.S. Treasuries $ 0 $ 0 $ 95 $ (4 ) $ 95 $ (4 ) Securities of U.S. Government agencies and corporations 19,546 (411 ) 5,332 (189 ) 24,878 (600 ) Mortgage-backed securities - residential 431,332 (8,695 ) 141,519 (7,182 ) 572,851 (15,877 ) Mortgage-backed securities - commercial 281,842 (3,637 ) 151,185 (8,387 ) 433,027 (12,024 ) Collateralized mortgage obligations 658,749 (10,407 ) 133,153 (5,756 ) 791,902 (16,163 ) Obligations of state and other political subdivisions 304,298 (3,976 ) 37,683 (1,936 ) 341,981 (5,912 ) Asset-backed securities 206,708 (1,125 ) 20,776 (374 ) 227,484 (1,499 ) Other securities 17,901 (192 ) 4,678 (108 ) 22,579 (300 ) Total $ 1,920,376 $ (28,443 ) $ 494,421 $ (23,936 ) $ 2,414,797 $ (52,379 ) December 31, 2017 Less than 12 months 12 months or more Total Fair Unrealized Fair Unrealized Fair Unrealized (Dollars in thousands) value loss value loss value loss U.S. Treasuries $ 97 $ (1 ) $ 0 $ 0 $ 97 $ (1 ) Securities of U.S. Government agencies and corporations 11,092 (76 ) 0 0 11,092 (76 ) Mortgage-backed securities - residential 175,183 (1,109 ) 108,782 (3,025 ) 283,965 (4,134 ) Mortgage-backed securities - commercial 132,818 (1,713 ) 72,139 (2,704 ) 204,957 (4,417 ) Collateralized mortgage obligations 164,909 (1,138 ) 101,436 (2,325 ) 266,345 (3,463 ) Obligations of state and other political subdivisions 38,450 (507 ) 21,639 (435 ) 60,089 (942 ) Asset-backed securities 44,941 (200 ) 24,396 (106 ) 69,337 (306 ) Other securities 2,605 (1 ) 7,124 (286 ) 9,729 (287 ) Total $ 570,095 $ (4,745 ) $ 335,516 $ (8,881 ) $ 905,611 $ (13,626 )

LOANS AND LEASES

LOANS AND LEASES	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
LOANS AND LEASES	LOANS AND LEASES First Financial offers clients a variety of commercial and consumer loan and lease products with distinct interest rates and payment terms. Commercial loan categories include C&I, CRE, construction real estate and lease financing. Consumer loan categories include residential real estate, home equity, installment and credit card. Lending activities are primarily concentrated in states where the Bank operates banking centers (Ohio, Indiana, Kentucky and Illinois). First Financial also offers two nationwide lending platforms, one that provides equipment and leasehold improvement financing for franchisees in the quick service and casual dining restaurant sector and another that provides loans primarily to insurance agents and brokers that are secured by commissions and cash collateral. Credit Quality. To facilitate the monitoring of credit quality for commercial loans, and for purposes of determining an appropriate ALLL, First Financial utilizes the following categories of credit grades: Pass - Higher quality loans that do not fit any of the other categories described below. Special Mention - First Financial assigns a special mention rating to loans and leases with potential weaknesses that deserve management's close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the loan or lease or in First Financial's credit position at some future date. Substandard - First Financial assigns a substandard rating to loans or leases that are inadequately protected by the current sound financial worth and paying capacity of the borrower or of the collateral pledged, if any. Substandard loans and leases have well-defined weaknesses that jeopardize repayment of the debt. Substandard loans and leases are characterized by the distinct possibility that the Company will sustain some loss if the deficiencies are not addressed. Doubtful - First Financial assigns a doubtful rating to loans and leases with all the attributes of a substandard rating with the added characteristic that the weaknesses make collection or liquidation in full highly questionable and improbable, on the basis of currently existing facts, conditions and values. The possibility of loss is extremely high, but because of certain important and reasonably specific pending factors that may work to the advantage and strengthening of the credit quality of the loan or lease, its classification as an estimated loss is deferred until its more exact status may be determined. Pending factors include proposed merger, acquisition or liquidation procedures, capital injection, perfecting liens on additional collateral and refinancing plans. The credit grades previously described are derived from standard regulatory rating definitions and are assigned upon initial approval of credit to borrowers and updated periodically thereafter. First Financial considers repayment performance to be the best indicator of credit quality for consumer loans. Consumer loans that have principal and interest payments that are past due by 90 days or more are generally classified as nonperforming. Additionally, consumer loans that have been modified in a TDR are classified as nonperforming. Purchased impaired loans are not classified as nonperforming as the loans are considered to be performing under FASB ASC Topic 310-30. Commercial and consumer credit exposure by risk attribute was as follows: As of September 30, 2018 Commercial Real Estate Lease (Dollars in thousands) & industrial Construction Commercial financing Total Pass $ 2,335,925 $ 552,973 $ 3,757,627 $ 92,551 $ 6,739,076 Special Mention 39,060 12,094 49,463 0 100,617 Substandard 51,605 10 61,053 2,766 115,434 Doubtful 0 0 0 0 0 Total $ 2,426,590 $ 565,077 $ 3,868,143 $ 95,317 $ 6,955,127 (Dollars in thousands) Residential real estate Home equity Installment Credit card Total Performing $ 919,440 $ 809,653 $ 97,097 $ 45,741 $ 1,871,931 Nonperforming 13,522 6,480 316 0 20,318 Total $ 932,962 $ 816,133 $ 97,413 $ 45,741 $ 1,892,249 As of December 31, 2017 Commercial Real Estate Lease (Dollars in thousands) & industrial Construction Commercial financing Total Pass $ 1,882,464 $ 467,687 $ 2,446,999 $ 88,078 $ 4,885,228 Special Mention 6,226 0 4,436 0 10,662 Substandard 24,053 43 38,656 1,269 64,021 Doubtful 0 0 0 0 0 Total $ 1,912,743 $ 467,730 $ 2,490,091 $ 89,347 $ 4,959,911 (Dollars in thousands) Residential real estate Home equity Installment Credit card Total Performing $ 463,459 $ 489,148 $ 41,331 $ 46,691 $ 1,040,629 Nonperforming 7,932 4,456 255 0 12,643 Total $ 471,391 $ 493,604 $ 41,586 $ 46,691 $ 1,053,272 Delinquency. Loans are considered past due or delinquent when the contractual principal or interest due in accordance with the terms of the loan agreement remains unpaid after the date of the scheduled payment. Loan delinquency, including loans classified as nonaccrual, was as follows: As of September 30, 2018 (Dollars in thousands) 30 – 59 60 – 89 > 90 days Total Current Subtotal Purchased impaired Total > 90 days Loans Commercial & industrial $ 1,991 $ 1,613 $ 2,662 $ 6,266 $ 2,414,484 $ 2,420,750 $ 5,840 $ 2,426,590 $ 0 Lease financing 0 0 0 0 95,317 95,317 0 95,317 0 Construction real estate 283 0 0 283 564,535 564,818 259 565,077 0 Commercial real estate 4,513 407 16,296 21,216 3,789,238 3,810,454 57,689 3,868,143 0 Residential real estate 2,796 1,828 2,825 7,449 888,367 895,816 37,146 932,962 0 Home equity 3,435 1,336 3,153 7,924 804,670 812,594 3,539 816,133 0 Installment 201 21 282 504 96,360 96,864 549 97,413 0 Credit card 301 179 144 624 45,117 45,741 0 45,741 144 Total $ 13,520 $ 5,384 $ 25,362 $ 44,266 $ 8,698,088 $ 8,742,354 $ 105,022 $ 8,847,376 $ 144 As of December 31, 2017 (Dollars in thousands) 30 – 59 60 – 89 > 90 days Total Current Subtotal Purchased impaired Total > 90 days Loans Commercial & industrial $ 755 $ 1,657 $ 5,078 $ 7,490 $ 1,901,821 $ 1,909,311 $ 3,432 $ 1,912,743 $ 0 Lease financing 485 0 0 485 88,862 89,347 0 89,347 0 Construction real estate 234 0 0 234 467,216 467,450 280 467,730 0 Commercial real estate 1,716 201 8,777 10,694 2,419,969 2,430,663 59,428 2,490,091 0 Residential real estate 526 811 1,992 3,329 430,500 433,829 37,562 471,391 0 Home equity 2,716 394 1,753 4,863 485,127 489,990 3,614 493,604 0 Installment 179 29 205 413 40,529 40,942 644 41,586 0 Credit card 285 87 62 434 46,257 46,691 0 46,691 62 Total $ 6,896 $ 3,179 $ 17,867 $ 27,942 $ 5,880,281 $ 5,908,223 $ 104,960 $ 6,013,183 $ 62 Nonaccrual. Loans are classified as nonaccrual when, in the opinion of management, collection of principal or interest is doubtful or when principal or interest payments are 90 days or more past due. Generally, loans are classified as nonaccrual due to the continued failure by the borrower to adhere to contractual payment terms, coupled with other pertinent factors. When a loan is classified as nonaccrual, the accrual of interest income is discontinued and previously accrued but unpaid interest is reversed. Any payments received while a loan is on nonaccrual status are applied as a reduction to the carrying value of the loan. A loan classified as nonaccrual may return to accrual status if collection of future principal and interest payments is no longer doubtful. Purchased impaired loans are classified as performing, even though they may be contractually past due, as any nonpayment of contractual principal or interest is considered in the periodic re-estimation of expected cash flows and is included in the resulting recognition of current period provision for loan and lease losses or prospective yield adjustments. Troubled Debt Restructurings. A loan modification is considered a TDR when the borrower is experiencing financial difficulty and concessions are made by the Company that would not otherwise be considered for a borrower with similar credit characteristics. The most common types of modifications include interest rate reductions, maturity extensions and modifications to principal amortization, including interest-only structures. Modified terms are dependent upon the financial position and needs of the individual borrower. If the modification agreement is violated, the loan is managed by the Company’s credit administration group for resolution, which may result in foreclosure in the case of real estate. TDRs are generally classified as nonaccrual for a minimum period of six months and may qualify for return to accrual status once they have demonstrated performance with the restructured terms of the loan agreement. First Financial had 187 TDRs totaling $25.0 million at September 30, 2018 , including $20.3 million on accrual status and $4.7 million classified as nonaccrual. First Financial had an insignificant amount of commitments outstanding to lend additional funds to borrowers whose loan terms have been modified through TDRs, and the ALLL included reserves of $2.3 million related to TDRs at September 30, 2018 . For the three months ended September 30, 2018 and 2017, the Company charged off $0.7 million and $0.1 million , respectively, for the portion of TDRs determined to be uncollectible. For the nine months ended September 30, 2018 and 2017, the Company charged off $0.8 million and $0.2 million , respectively, for the portion of TDRs determined to be uncollectible. Additionally, as of September 30, 2018 , $12.6 million of accruing TDRs have been performing in accordance with the restructured terms for more than one year. First Financial had 214 TDRs totaling $23.9 million at December 31, 2017 , including $17.5 million of loans on accrual status and $6.4 million classified as nonaccrual. First Financial had an insignificant amount of commitments outstanding to lend additional funds to borrowers whose loan terms had been modified through TDRs. At December 31, 2017 , the ALLL included reserves of $1.3 million related to TDRs, and $17.2 million of the accruing TDRs had been performing in accordance with the restructured terms for more than one year. The following tables provide information on loan modifications classified as TDRs during the three and nine months ended September 30, 2018 and 2017 : Three months ended September 30, 2018 September 30, 2017 (Dollars in thousands) Number of loans Pre-modification loan balance Period end balance Number of loans Pre-modification loan balance Period end balance Commercial & industrial 0 $ 0 $ 0 1 $ 45 $ 37 Construction real estate 0 0 0 0 0 0 Commercial real estate 0 0 0 1 285 285 Residential real estate 1 148 143 6 416 315 Home equity 1 10 10 1 39 39 Installment 0 0 0 0 0 0 Total 2 $ 158 $ 153 9 $ 785 $ 676 Nine months ended September 30, 2018 September 30, 2017 (Dollars in thousands) Number of loans Pre-modification loan balance Period end balance Number of loans Pre-modification loan balance Period end balance Commercial & industrial 12 $ 7,149 $ 7,096 7 $ 5,724 $ 5,661 Construction real estate 0 0 0 0 0 0 Commercial real estate 6 2,119 2,088 7 1,791 1,734 Residential real estate 4 442 437 6 416 315 Home equity 1 10 10 1 39 39 Installment 0 0 0 0 0 0 Total 23 $ 9,720 $ 9,631 21 $ 7,970 $ 7,749 The following table provides information on how TDRs were modified during the three and nine months ended September 30, 2018 and 2017 : Three months ended Nine months ended September 30, September 30, (Dollars in thousands) 2018 2017 2018 2017 Extended maturities $ 143 $ 0 $ 3,031 $ 3,261 Adjusted interest rates 0 0 52 2,767 Combination of rate and maturity changes 0 285 0 465 Forbearance 0 354 6,199 1,181 Other (1) 10 37 349 75 Total $ 153 $ 676 $ 9,631 $ 7,749 (1) Includes covenant modifications and other concessions, or combination of concessions, that do not consist of interest rate adjustments, forbearance and maturity extensions First Financial considers repayment performance as an indication of the effectiveness of the Company's loan modifications. Borrowers that are 90 days or more past due on any principal or interest payments, or who prematurely terminate a restructured loan agreement without paying the contractual principal balance (for example, in a deed-in-lieu arrangement), are considered to be in payment default of the terms of the TDR agreement. For the nine months ended September 30, 2018 , there was one TDR, insignificant in amount, for which there was a payment default during the period that occurred within twelve months of the loan modification. There were no TDRs for which there was a payment default during the period that occurred within twelve months of the loan modification for the three months ended September 30, 2018 or the three or nine month periods ended September 30, 2017 . Impaired Loans. Loans classified as nonaccrual and loans modified as TDRs are considered impaired. The following table provides information on impaired loans, excluding purchased impaired loans: (Dollars in thousands) September 30, 2018 December 31, 2017 Impaired loans Nonaccrual loans (1) Commercial & industrial $ 4,310 $ 5,229 Lease financing 0 82 Construction real estate 10 29 Commercial real estate 20,338 10,616 Residential real estate 11,365 4,140 Home equity 6,018 3,743 Installment 327 243 Nonaccrual loans 42,368 24,082 Accruing troubled debt restructurings 20,313 17,545 Total impaired loans $ 62,681 $ 41,627 (1) Nonaccrual loans include nonaccrual TDRs of $4.7 million and $6.4 million as of September 30, 2018 and December 31, 2017 , respectively. Three months ended Nine months ended September 30, September 30, (Dollars in thousands) 2018 2017 2018 2017 Interest income effect on impaired loans Gross amount of interest that would have been recorded under original terms $ 1,192 $ 761 $ 3,126 $ 2,735 Interest included in income Nonaccrual loans 169 140 395 445 Troubled debt restructurings 187 168 500 563 Total interest included in income 356 308 895 1,008 Net impact on interest income $ 836 $ 453 $ 2,231 $ 1,727 First Financial individually reviews all impaired commercial loan relationships, as well as consumer loan TDRs, greater than $250,000 , to determine if a specific allowance is necessary based on the borrower’s overall financial condition, payment record, support from guarantors and the realizable value of any collateral. Specific allowances are based on discounted cash flows using the loan's initial effective interest rate or the fair value of the collateral for certain collateral dependent loans. First Financial's investment in impaired loans was as follows: As of September 30, 2018 As of December 31, 2017 (Dollars in thousands) Current balance Contractual principal balance Related allowance Current balance Contractual Related Loans with no related allowance recorded Commercial & industrial $ 9,209 $ 13,034 $ 0 $ 7,162 $ 8,460 $ 0 Lease financing 0 0 0 82 82 0 Construction real estate 10 27 0 29 60 0 Commercial real estate 26,722 32,706 0 18,423 20,837 0 Residential real estate 14,277 17,083 0 6,876 8,145 0 Home equity 6,554 7,337 0 4,356 5,399 0 Installment 332 639 0 255 422 0 Total 57,104 70,826 0 37,183 43,405 0 Loans with an allowance recorded Commercial & industrial 2,776 2,776 1,562 169 169 169 Lease financing 0 0 0 0 0 0 Construction real estate 0 0 0 0 0 0 Commercial real estate 1,668 2,322 66 3,119 3,120 448 Residential real estate 1,033 1,033 160 1,056 1,063 160 Home equity 100 100 2 100 100 2 Installment 0 0 0 0 0 0 Total 5,577 6,231 1,790 4,444 4,452 779 Total Commercial & industrial 11,985 15,810 1,562 7,331 8,629 169 Lease financing 0 0 0 82 82 0 Construction real estate 10 27 0 29 60 0 Commercial real estate 28,390 35,028 66 21,542 23,957 448 Residential real estate 15,310 18,116 160 7,932 9,208 160 Home equity 6,654 7,437 2 4,456 5,499 2 Installment 332 639 0 255 422 0 Total $ 62,681 $ 77,057 $ 1,790 $ 41,627 $ 47,857 $ 779 First Financial's average impaired loans by class and interest income recognized by class was as follows: Three months ended September 30, 2018 September 30, 2017 (Dollars in thousands) Average Interest Average Interest Loans with no related allowance recorded Commercial & industrial $ 10,033 $ 63 $ 13,730 $ 63 Lease financing 0 0 91 1 Construction real estate 17 0 950 0 Commercial real estate 28,689 136 23,187 147 Residential real estate 13,247 86 7,569 55 Home equity 6,463 31 3,791 26 Installment 318 1 290 1 Total 58,767 317 49,608 293 Loans with an allowance recorded Commercial & industrial 1,578 28 1,832 2 Lease financing 0 0 0 0 Construction real estate 0 0 0 0 Commercial real estate 1,012 3 652 5 Residential real estate 1,036 7 1,067 7 Home equity 100 1 101 1 Installment 0 0 0 0 Total 3,726 39 3,652 15 Total Commercial & industrial 11,611 91 15,562 65 Lease financing 0 0 91 1 Construction real estate 17 0 950 0 Commercial real estate 29,701 139 23,839 152 Residential real estate 14,283 93 8,636 62 Home equity 6,563 32 3,892 27 Installment 318 1 290 1 Total $ 62,493 $ 356 $ 53,260 $ 308 Nine months ended September 30, 2018 September 30, 2017 (Dollars in thousands) Average Interest Average Interest Loans with no related allowance recorded Commercial & industrial $ 8,950 $ 162 $ 14,669 $ 259 Lease financing 21 0 120 3 Construction real estate 22 2 744 0 Commercial real estate 25,044 375 21,563 451 Residential real estate 9,875 209 7,801 147 Home equity 5,339 78 3,951 77 Installment 299 2 351 4 Total 49,550 828 49,199 941 Loans with an allowance recorded Commercial & industrial 891 34 1,463 26 Lease financing 0 0 0 0 Construction real estate 0 0 0 0 Commercial real estate 1,376 9 2,513 18 Residential real estate 1,043 21 1,126 20 Home equity 100 3 101 3 Installment 0 0 0 0 Total 3,410 67 5,203 67 Total Commercial & industrial 9,841 196 16,132 285 Lease financing 21 0 120 3 Construction real estate 22 2 744 0 Commercial real estate 26,420 384 24,076 469 Residential real estate 10,918 230 8,927 167 Home equity 5,439 81 4,052 80 Installment 299 2 351 4 Total $ 52,960 $ 895 $ 54,402 $ 1,008 Acquired loans. Acquired loans are recorded at their estimated fair value at the time of acquisition. Estimated fair values for acquired loans are based on a discounted cash flow methodology that considers various factors including the type of loan and related collateral, classification status, interest rate, term of loan, whether or not the loan was amortizing and a discount rate reflecting the Company's assessment of risk inherent in the cash flow estimates. Acquired loans are grouped together according to similar characteristics and treated in the aggregate when applying various valuation techniques. First Financial evaluates acquired loans for impairment in accordance with the provisions of FASB ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality. Acquired loans with evidence of credit deterioration since origination are accounted for under FASB ASC Topic 310-30 and are referred to as purchased impaired loans. Interest income, through accretion of the difference between the carrying value of the loans and the expected cash flows (accretable difference) is recognized on all purchased impaired loans. First Financial had purchased impaired loans totaling $105.0 million at September 30, 2018 , which included $18.0 million acquired in the merger with MSFG. OREO. OREO consists of properties acquired by the Company primarily through the loan foreclosure or repossession process, that results in partial or total satisfaction of problem loans. Changes in OREO were as follows: Three months ended Nine months ended September 30, September 30, (Dollars in thousands) 2018 2017 2018 2017 Balance at beginning of period $ 1,853 $ 5,961 $ 2,781 $ 6,284 Additions Commercial & industrial 79 1,559 1,269 1,731 Residential real estate 739 235 1,723 2,313 Total additions 818 1,794 2,992 4,044 Disposals Commercial & industrial (181 ) (3,684 ) (2,611 ) (5,291 ) Residential real estate (117 ) (821 ) (527 ) (1,506 ) Total disposals (298 ) (4,505 ) (3,138 ) (6,797 ) Valuation adjustment Commercial & industrial (258 ) (102 ) (355 ) (264 ) Residential real estate (197 ) (32 ) (362 ) (151 ) Total valuation adjustment (455 ) (134 ) (717 ) (415 ) Balance at end of period $ 1,918 $ 3,116 $ 1,918 $ 3,116

ALLOWANCE FOR LOAN AND LEASE LO

ALLOWANCE FOR LOAN AND LEASE LOSSES	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
ALLOWANCE FOR LOAN AND LEASE LOSSES	ALLOWANCE FOR LOAN AND LEASE LOSSES Management maintains the ALLL at a level that it considers sufficient to absorb probable incurred loan and lease losses inherent in the portfolio. Management determines the adequacy of the ALLL based on historical loss experience as well as other significant factors such as composition of the portfolio, economic conditions, geographic footprint, the results of periodic internal and external evaluations of delinquent, nonaccrual and classified loans and any other adverse situations that may affect a specific borrower's ability to repay, including the timing of future payments. The ALLL is increased by provision expense and decreased by charge-offs, net of recoveries of amounts previously charged-off. First Financial's policy is to charge-off all or a portion of a loan when, in management's opinion, it is unlikely to collect the principal amount owed in full either through payments from the borrower or from the liquidation of collateral. Changes in the ALLL by loan category were as follows: Three months ended September 30, 2018 Real Estate (Dollars in thousands) Commercial and industrial Lease financing Construction Commercial Residential Home Equity Installment Credit card Total Allowance for loan and lease losses: Balance at beginning of period $ 17,528 $ 797 $ 3,985 $ 20,511 $ 4,668 $ 4,801 $ 290 $ 1,496 $ 54,076 Provision for loan and lease losses 2,035 287 (114 ) 959 50 63 (288 ) 246 3,238 Gross charge-offs (232 ) 0 0 (902 ) (145 ) (351 ) (43 ) (390 ) (2,063 ) Recoveries 627 0 146 786 71 419 351 64 2,464 Total net charge-offs 395 0 146 (116 ) (74 ) 68 308 (326 ) 401 Ending allowance for loan and lease losses $ 19,958 $ 1,084 $ 4,017 $ 21,354 $ 4,644 $ 4,932 $ 310 $ 1,416 $ 57,715 Three months ended September 30, 2017 Real Estate (Dollars in thousands) Commercial and industrial Lease financing Construction Commercial Residential Home Equity Installment Credit card Total Allowance for loan and lease losses: Balance at beginning of period $ 18,313 $ 550 $ 3,416 $ 21,717 $ 5,016 $ 4,138 $ 355 $ 1,368 $ 54,873 Provision for loan and lease losses 3,024 507 (178 ) (1,003 ) (243 ) 819 (80 ) 107 2,953 Loans charged off (4,122 ) 0 0 (58 ) (23 ) (71 ) (24 ) (201 ) (4,499 ) Recoveries 325 0 0 585 70 110 74 43 1,207 Total net charge-offs (3,797 ) 0 0 527 47 39 50 (158 ) (3,292 ) Ending allowance for loan and lease losses $ 17,540 $ 1,057 $ 3,238 $ 21,241 $ 4,820 $ 4,996 $ 325 $ 1,317 $ 54,534 Nine months ended September 30, 2018 Real Estate (Dollars in thousands) Commercial & industrial Lease financing Construction Commercial Residential Home equity Installment Credit card Total Allowance for loan and lease losses: Balance at beginning of period $ 17,598 $ 675 $ 3,577 $ 20,930 $ 4,683 $ 4,935 $ 307 $ 1,316 $ 54,021 Provision for loan and lease losses 6,252 408 294 1,155 136 (60 ) (201 ) 1,292 9,276 Loans charged off (5,473 ) 0 0 (3,156 ) (342 ) (978 ) (277 ) (1,328 ) (11,554 ) Recoveries 1,581 1 146 2,425 167 1,035 481 136 5,972 Total net charge-offs (3,892 ) 1 146 (731 ) (175 ) 57 204 (1,192 ) (5,582 ) Ending allowance for loan and lease losses $ 19,958 $ 1,084 $ 4,017 $ 21,354 $ 4,644 $ 4,932 $ 310 $ 1,416 $ 57,715 Nine months ended September 30, 2017 Real Estate (Dollars in thousands) Commercial & industrial Lease financing Construction Commercial Residential Home equity Installment Credit card Total Allowance for loan and lease losses: Balance at beginning of period $ 19,225 $ 716 $ 3,282 $ 26,540 $ 3,208 $ 3,043 $ 388 $ 1,559 $ 57,961 Provision for loan and lease losses 5,965 340 (133 ) (6,510 ) 1,781 2,150 (52 ) 246 3,787 Loans charged off (8,930 ) 0 0 (1,028 ) (307 ) (635 ) (199 ) (648 ) (11,747 ) Recoveries 1,280 1 89 2,239 138 438 188 160 4,533 Total net charge-offs (7,650 ) 1 89 1,211 (169 ) (197 ) (11 ) (488 ) (7,214 ) Ending allowance for loan and lease losses $ 17,540 $ 1,057 $ 3,238 $ 21,241 $ 4,820 $ 4,996 $ 325 $ 1,317 $ 54,534 As of December 31, 2017 Real Estate (Dollars in thousands) Commercial & industrial Lease financing Construction Commercial Residential Home equity Installment Credit card Total Ending allowance balance attributable to loans Individually evaluated for impairment $ 169 $ 0 $ 0 $ 448 $ 160 $ 2 $ 0 $ 0 $ 779 Collectively evaluated for impairment 17,429 675 3,577 20,482 4,523 4,933 307 1,316 53,242 Ending allowance for loan and lease losses $ 17,598 $ 675 $ 3,577 $ 20,930 $ 4,683 $ 4,935 $ 307 $ 1,316 $ 54,021 Loans Individually evaluated for impairment $ 7,331 $ 82 $ 29 $ 21,542 $ 7,932 $ 4,456 $ 255 $ 0 $ 41,627 Collectively evaluated for impairment 1,905,412 89,265 467,701 2,468,549 463,459 489,148 41,331 46,691 5,971,556 Total loans $ 1,912,743 $ 89,347 $ 467,730 $ 2,490,091 $ 471,391 $ 493,604 $ 41,586 $ 46,691 $ 6,013,183 As of September 30, 2018 Real Estate (Dollars in thousands) Commercial & industrial Lease financing Construction Commercial Residential Home equity Installment Credit card Total Ending allowance balance attributable to loans Individually evaluated for impairment $ 1,562 $ 0 $ 0 $ 66 $ 160 $ 2 $ 0 $ 0 $ 1,790 Collectively evaluated for impairment 18,396 1,084 4,017 21,288 4,484 4,930 310 1,416 55,925 Ending allowance for loan and lease losses $ 19,958 $ 1,084 $ 4,017 $ 21,354 $ 4,644 $ 4,932 $ 310 $ 1,416 $ 57,715 Loans Individually evaluated for impairment $ 11,985 $ 0 $ 10 $ 28,390 $ 15,310 $ 6,654 $ 332 $ 0 $ 62,681 Collectively evaluated for impairment 2,414,605 95,317 565,067 3,839,753 917,652 809,479 97,081 45,741 8,784,695 Total loans $ 2,426,590 $ 95,317 $ 565,077 $ 3,868,143 $ 932,962 $ 816,133 $ 97,413 $ 45,741 $ 8,847,376

GOODWILL AND OTHER INTANGIBLE A

GOODWILL AND OTHER INTANGIBLE ASSETS	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLE ASSETS	GOODWILL AND OTHER INTANGIBLE ASSETS Goodwill. Assets and liabilities acquired in a business combination are recorded at their estimated fair values as of the acquisition date. The excess cost of the acquisition over the fair value of net assets acquired is recorded as goodwill. Changes in the carrying amount of goodwill for the nine months ended September 30, 2018 and the year ended December 31, 2017 were as follows: (Dollars in thousands) September 30, December 31, Balance at beginning of year $ 204,084 $ 204,084 Goodwill resulting from business combinations 676,949 0 Balance at end of period $ 881,033 $ 204,084 First Financial recorded additions to goodwill resulting from the merger with MSFG in 2018, while no additions to goodwill were recorded during 2017. For further detail on the merger with MSFG, see Note 16 - Business Combinations. Goodwill is evaluated for impairment on an annual basis as of October 1 of each year, or whenever events or changes in circumstances indicate that the fair value of a reporting unit may be below its carrying value. First Financial performed its most recent annual impairment test as of October 1, 2017 and no impairment was indicated. As of September 30, 2018 , no events or changes in circumstances indicated that the fair value of a reporting unit was below its carrying value. Other intangible assets. As of September 30, 2018 and December 31, 2017 , First Financial had $53.3 million and $5.3 million , respectively, of other intangible assets included in Goodwill and other intangibles in the Consolidated Balance Sheets, which primarily consist of core deposit intangibles. Core deposit intangibles represent the estimated fair value of acquired customer deposit relationships on the date of acquisition and are amortized on an accelerated basis over their estimated useful lives. Core deposit intangibles were $40.2 million and $3.3 million as of September 30, 2018 and December 31, 2017 , respectively. First Financial's core deposit intangibles have an estimated weighted average remaining life of 9.1 years . Amortization expense recognized on intangible assets for the three months ended September 30, 2018 and 2017 was $2.5 million and $0.3 million , respectively. Amortization expense recognized on intangible assets for the nine months ended September 30, 2018 and 2017 was $5.1 million and $1.0 million

BORROWINGS

BORROWINGS	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
BORROWINGS	BORROWINGS Short-term borrowings on the Consolidated Balance Sheets include repurchase agreements utilized for corporate sweep accounts with cash management account agreements in place, overnight advances from the FHLB and a short-term line of credit. All repurchase agreements are subject to terms and conditions agreed to by the Bank and the client. To secure its liability to the client, the Bank is authorized to sell or repurchase U.S. Treasury, government agency and mortgage-backed securities. First Financial had $1.2 billion in short-term borrowings with the FHLB at September 30, 2018 and $742.3 million as of December 31, 2017 . These short-term borrowings are used to manage normal liquidity needs and support the Company's asset and liability management strategies. First Financial has a $30.0 million short-term credit facility with an unaffiliated bank that matures on September 20, 2019. This facility can have a variable or fixed interest rate and provides First Financial additional liquidity, if needed, for various corporate activities including the repurchase of First Financial common stock and the payment of dividends to shareholders. As of September 30, 2018 and December 31, 2017 , there was no outstanding balance. The credit agreement requires First Financial to comply with certain covenants including those related to asset quality and capital levels, and First Financial was in compliance with all covenants associated with this facility as of September 30, 2018 and December 31, 2017 . First Financial had $570.0 million and $119.7 million of long-term debt as of September 30, 2018 and December 31, 2017, respectively, which included subordinated notes, FHLB long term advances and an interest free loan with a municipality. The following is a summary of First Financial's long-term debt: September 30, 2018 December 31, 2017 (Dollars in thousands) Amount Average rate Amount Average rate Subordinated notes $ 177,887 5.13 % $ 120,000 5.13 % Unamortized discount and debt issuance costs (8,671 ) N/A (1,362 ) N/A FHLB borrowings 400,046 2.09 % 241 1.09 % Capital loan with municipality 775 0.00 % 775 0.00 % Total long-term debt $ 570,037 3.06 % $ 119,654 5.14 % In 2015, First Financial issued $120.0 million of subordinated notes, which have a fixed interest rate of 5.125% payable semiannually and mature on August 25, 2025. These notes are not redeemable by the Company, or callable by the holders of the notes prior to maturity. The subordinated notes are treated as Tier 2 capital for regulatory capital purposes. In addition, First Financial acquired $49.5 million of variable rate subordinated notes in the MSFG merger that were issued to previously formed trusts in exchange for the trust proceeds. Interest on the acquired subordinated notes is payable quarterly, in arrears, and the Company has the option to defer interest payments for a period not to exceed 20 consecutive quarters. The acquired subordinated notes mature 30 years after the date of original issuance and may be called at par following the 5 year anniversary of issuance. First Financial also acquired $8.4 million of 6.94% fixed rate private placement subordinated debt in conjunction with the MSFG merger that was issued in 2015 and matures in 2025. These notes are redeemable by the Company at par following the 5 year anniversary of issuance. In addition to subordinated notes, long-term debt included $400.0 million and $0.2 million of fixed rate FHLB long-term advances as of September 30, 2018 and December 31, 2017 , respectively. As of September 30, 2018 , long-term FHLB advances had a weighted average interest rate of 2.09%

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Shareholders’ equity is affected by transactions and valuations of asset and liability positions that require adjustments to accumulated other comprehensive income (loss). The related tax effects allocated to other comprehensive income and reclassifications out of accumulated other comprehensive income (loss) are as follows: Three months ended September 30, 2018 Total other comprehensive income (loss) Total accumulated other comprehensive income (loss) (Dollars in thousands) Prior to reclass Reclass from Pre-tax Tax effect Net of tax Beginning balance Net activity Ending balance Unrealized gain (loss) on debt securities $ (13,138 ) $ (167 ) $ (12,971 ) $ 2,786 $ (10,185 ) $ (19,179 ) $ (10,185 ) $ (29,364 ) Unrealized gain (loss) on derivatives 130 0 130 (31 ) 99 (386 ) 99 (287 ) Retirement obligation 0 (452 ) 452 (105 ) 347 (23,593 ) 347 (23,246 ) Total $ (13,008 ) $ (619 ) $ (12,389 ) $ 2,650 $ (9,739 ) $ (43,158 ) $ (9,739 ) $ (52,897 ) Three months ended September 30, 2017 Total other comprehensive income (loss) Total accumulated other comprehensive income (loss) (Dollars in thousands) Prior to reclass Reclass from Pre-tax Tax effect Net of tax Beginning balance Net activity Ending balance Unrealized gain (loss) on debt securities $ 2,612 $ 276 $ 2,336 $ (835 ) $ 1,501 $ 1,014 $ 1,501 $ 2,515 Unrealized gain (loss) on derivatives 202 0 202 (73 ) 129 (835 ) 129 (706 ) Retirement obligation 0 (335 ) 335 (122 ) 213 (22,401 ) 213 (22,188 ) Total $ 2,814 $ (59 ) $ 2,873 $ (1,030 ) $ 1,843 $ (22,222 ) $ 1,843 $ (20,379 ) Nine months ended September 30, 2018 Total other comprehensive income Total accumulated other comprehensive income (loss) (Dollars in thousands) Prior to Reclass Pre-tax Tax effect Net of tax Beginning balance Net activity Cumulative effect of accounting change Ending balance Unrealized gain (loss) on debt securities $ (37,130 ) $ (197 ) $ (36,933 ) $ 7,940 $ (28,993 ) $ (182 ) $ (28,993 ) $ (189 ) $ (29,364 ) Unrealized gain (loss) on derivatives 535 0 535 (121 ) 414 (577 ) 414 (124 ) (287 ) Retirement obligation 0 (1,323 ) 1,323 (159 ) 1,164 (19,631 ) 1,164 (4,779 ) (23,246 ) Total $ (36,595 ) $ (1,520 ) $ (35,075 ) $ 7,660 $ (27,415 ) $ (20,390 ) $ (27,415 ) $ (5,092 ) $ (52,897 ) Nine months ended September 30, 2017 Total other comprehensive income Total accumulated other comprehensive income (loss) (Dollars in thousands) Prior to Reclass Pre-tax Tax effect Net of tax Beginning balance Net activity Ending balance Unrealized gain (loss) on debt securities $ 12,614 $ 1,630 $ 10,984 $ (3,920 ) $ 7,064 $ (4,549 ) $ 7,064 $ 2,515 Unrealized gain (loss) on derivatives 607 0 607 (222 ) 385 (1,091 ) 385 (706 ) Retirement obligation 0 (1,005 ) 1,005 (390 ) 615 (22,803 ) 615 (22,188 ) Total $ 13,221 $ 625 $ 12,596 $ (4,532 ) $ 8,064 $ (28,443 ) $ 8,064 $ (20,379 ) The following table presents the activity reclassified from accumulated other comprehensive income into income during the three and nine month periods ended September 30, 2018 and 2017, respectively: Amount reclassified from accumulated other comprehensive income (1) Three months ended Nine months ended September 30, September 30, (Dollars in thousands) 2018 2017 2018 2017 Affected Line Item in the Consolidated Statements of Income Realized gain (loss) on securities available-for-sale $ (167 ) $ 276 $ (197 ) $ 1,630 Net gain (loss) on sales of investments securities Defined benefit pension plan Amortization of prior service cost (2) 104 103 310 310 Other noninterest expense (2018) Salaries and employee benefits (2017) Recognized net actuarial loss (2) (556 ) (438 ) (1,633 ) (1,315 ) Other noninterest expense (2018) Defined benefit pension plan total (452 ) (335 ) (1,323 ) (1,005 ) Total reclassifications for the period, before tax $ (619 ) $ (59 ) $ (1,520 ) $ 625 (1) Negative amounts are reductions to net income. (2)

DERIVATIVES

DERIVATIVES	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVES	DERIVATIVES First Financial uses certain derivative instruments, including interest rate caps, floors and swaps, to meet the needs of its clients while managing the interest rate risk associated with certain transactions. First Financial does not use derivatives for speculative purposes. First Financial primarily utilizes interest rate swaps as a means to offer borrowers credit-based products that meet their needs. First Financial may also utilize interest rate swaps to manage the interest rate risk profile of the Company. Interest rate payments are exchanged with counterparties based on the notional amount established in the interest rate agreement. As only interest rate payments are exchanged, the cash requirements and credit risk associated with interest rate swaps are significantly less than the notional amount and the Company’s credit risk exposure is limited to the market value of the instruments. First Financial manages market value credit risk through counterparty credit policies, which require the Company to maintain a total derivative notional position of less than 35% of assets, total credit exposure of less than 3% of capital and no single counterparty credit risk exposure greater than $20.0 million . The Company is currently below all single counterparty and portfolio limits. Client Derivatives. First Financial utilizes interest rate swaps as a means to offer commercial borrowers fixed rate funding while providing the Company with floating rate assets. The following table details the classification and amounts recognized in the Consolidated Balance Sheets for client derivatives: September 30, 2018 December 31, 2017 Estimated fair value Estimated fair value (Dollars in thousands) Balance sheet classification Notional amount Gain Loss Notional amount Gain Loss Client derivatives - instruments associated with loans Matched interest rate swaps with borrower Accrued interest and other assets $ 1,312,293 $ 4,046 $ (29,240 ) $ 837,040 $ 7,153 $ (5,529 ) Matched interest rate swaps with counterparty Accrued interest and other liabilities 1,312,293 29,240 (4,038 ) 837,040 5,529 (7,158 ) Total $ 2,624,586 $ 33,286 $ (33,278 ) $ 1,674,080 $ 12,682 $ (12,687 ) At September 30, 2018 , the Company had a total counterparty notional amount outstanding of $1.3 billion , spread among thirteen counterparties, with an outstanding asset from these contracts of $26.0 million . At December 31, 2017 , the Company had a total counterparty notional amount outstanding of $837.5 million , spread among thirteen counterparties, with an outstanding liability from these contracts of $1.3 million . First Financial monitors its derivative credit exposure to borrowers by monitoring the creditworthiness of the related loan customers through the Company's normal credit review processes. Additionally, the Company's ALLL Committee monitors derivative credit risk exposure related to problem loans through the Company's ALLL committee. First Financial considers the market value of a derivative instrument to be part of the carrying value of the related loan for these purposes as the borrower is contractually obligated to pay First Financial this amount in the event the derivative contract is terminated. In connection with its use of derivative instruments, First Financial and its counterparties may be required to post cash collateral to offset the market position of the derivative instruments. First Financial maintains the right to offset these derivative positions with the collateral posted against them by or with the relevant counterparties. First Financial classifies the derivative cash collateral outstanding with its counterparties as an adjustment to the fair value of the derivative contracts within Accrued interest and other assets or Accrued interest and other liabilities in the Consolidated Balance Sheets. The following table discloses the gross and net amounts of client derivative liabilities recognized in the Consolidated Balance Sheets: September 30, 2018 December 31, 2017 (Dollars in thousands) Gross amounts of recognized liabilities Gross amounts offset in the Consolidated Balance Sheets Net amounts of liabilities presented in the Consolidated Balance Sheets Gross amounts of recognized liabilities Gross amounts offset in the Consolidated Balance Sheets Net amounts of liabilities presented in the Consolidated Balance Sheets Client derivatives Matched interest rate swaps with counterparty $ 33,286 $ (4,900 ) $ 28,386 $ 12,687 $ 2,279 $ 14,966 The following table details the derivative financial instruments, the average remaining maturities and the weighted-average interest rates being paid and received by First Financial at September 30, 2018 : Weighted-average rate (Dollars in thousands) Notional amount Average maturity (years) Fair value Receive Pay Client derivatives Receive fixed, matched interest rate swaps with borrower $ 1,312,293 4.6 $ (25,194 ) 4.62 % 4.23 % Pay fixed, matched interest rate swaps with counterparty 1,312,293 4.6 25,202 4.23 % 4.62 % Total client derivatives $ 2,624,586 4.6 $ 8 4.42 % 4.42 % Credit Derivatives. In conjunction with participating interests in commercial loans, First Financial periodically enters into risk participation agreements with counterparties whereby First Financial assumes a portion of the credit exposure associated with an interest rate swap on the participated loan in exchange for a fee. Under these agreements, First Financial will make payments to the counterparty if the loan customer defaults on its obligation to perform under the interest rate swap contract with the counterparty. The total notional value of these agreements totaled $150.1 million as of September 30, 2018 and $95.9 million as of December 31, 2017 . The fair value of these agreements is recorded in Accrued interest and other liabilities on the Consolidated Balance Sheets and was insignificant at September 30, 2018 and $0.1 million at December 31, 2017 . Mortgage Derivatives. First Financial enters into IRLCs and forward commitments for the future delivery of mortgage loans to third party investors, which are considered derivatives. When borrowers secure an IRLC with First Financial and the loan is intended to be sold, First Financial will enter into forward commitments for the future delivery of the loans to third party investors in order to hedge against the effect of changes in interest rates impacting IRLCs and loans held for sale. At September 30, 2018 , the notional amount of the IRLCs was $20.8 million and the notional amount of forward commitments was $20.8 million . As of December 31, 2017 , the notional amount of IRLCs was $12.3 million and the notional amount of forward commitments was $15.4 million . The fair value of these agreements was insignificant at September 30, 2018 and $0.1 million December 31, 2017

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES First Financial offers a variety of financial instruments including standby letters of credit and outstanding commitments to extend credit to assist clients in meeting their requirement for liquidity and credit enhancement. GAAP does not require these financial instruments to be recorded in the Consolidated Financial Statements. First Financial utilizes the same credit policies in issuing commitments and conditional obligations as it does for credit instruments recorded on the Consolidated Balance Sheets. First Financial’s exposure to credit loss in the event of nonperformance by the counterparty is represented by the contractual amounts of those instruments. First Financial utilizes the ALLL methodology to maintain a reserve that it considers sufficient to absorb probable incurred losses inherent in letters of credit and outstanding loan commitments. First Financial had $0.7 million and $0.5 million of reserves for unfunded commitments recorded in Accrued interest and other liabilities on the Consolidated Balance Sheets as of September 30, 2018 and December 31, 2017 , respectively. Loan commitments. Loan commitments are agreements to extend credit to a client, absent any violation of conditions established in the commitment agreement. 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 amount of collateral obtained, if deemed necessary by First Financial upon extension of credit, is based on management’s credit evaluation of the client. The collateral held varies, but may include securities, real estate, inventory, plant or equipment. First Financial had commitments outstanding to extend credit totaling $2.9 billion and $2.1 billion at September 30, 2018 and December 31, 2017 , respectively. As of September 30, 2018 , loan commitments with a fixed interest rate totaled $202.7 million while commitments with variable interest rates totaled $2.7 billion . At December 31, 2017 , loan commitments with a fixed interest rate totaled $44.3 million while commitments with variable interest rates totaled $2.0 billion . First Financial's fixed rate loan commitments have interest rates ranging from 0.00% to 21.00% and maturities ranging from less than 1 year to 30 years . Letters of credit. Letters of credit are conditional commitments issued by First Financial to guarantee the performance of a client to a third party. First Financial’s portfolio of letters of credit consists primarily of performance assurances made on behalf of clients who have a contractual commitment to produce or deliver goods or services. The risk to First Financial arises from its obligation to make payment in the event of the client's contractual default to produce the contracted good or service to a third party. First Financial issued letters of credit aggregating $34.0 million and $25.3 million at September 30, 2018 and December 31, 2017 , respectively. Management conducts regular reviews of these instruments on an individual client basis. Investments in affordable housing tax credits. First Financial has made investments in certain qualified affordable housing tax credits. These credits are an indirect federal subsidy that provide tax incentives to encourage investment in the development, acquisition and rehabilitation of affordable rental housing, and allow investors to claim tax credits and other tax benefits (such as deductions from taxable income for operating losses) on their federal income tax returns. The principal risk associated with qualified affordable housing investments is the potential for noncompliance with the tax code requirements, such as failure to rent property to qualified tenants, resulting in the unavailability or recapture of the tax credits and other tax benefits. Investments in affordable housing projects are accounted for under the proportional amortization method and are included in Accrued interest and other assets in the Consolidated Balance Sheets. First Financial's affordable housing commitments totaled $42.2 million and $35.9 million as of September 30, 2018 and December 31, 2017 , respectively. The Company recognized tax credits of $1.3 million and $0.8 million and $3.6 million and $2.4 million for the three months and nine months ended September 30, 2018 and 2017 , respectively. The Company recognized amortization expense which was included in income tax expense of $1.4 million and $1.0 million for the three months ended September 30, 2018 and 2017 , respectively and $4.3 million and $3.2 million for the nine months ended September 30, 2018 and 2017 , respectively. First Financial had no affordable housing contingent commitments as of September 30, 2018 or December 31, 2017 . Investments in historic tax credits. First Financial has noncontrolling financial investments in private investment funds and partnerships which are not consolidated. These investments may generate a return through the realization of federal and state income tax credits, as well as other tax benefits, such as tax deductions from net operating losses of the investments over a period of time. Investments in historic tax credits are accounted for under the equity method of accounting and are carried in Accrued interest and other assets on the Consolidated Balance Sheets. The Company’s recorded investment in these entities was approximately $2.9 million at September 30, 2018 and $3.0 million at December 31, 2017 . The maximum exposure to loss related to these investments was $2.9 million at September 30, 2018 and $3.0 million at December 31, 2017 , representing the Company’s investment balance and its unfunded commitments to invest additional amounts. Investments in historic tax credits resulted in $0.1 million of tax credits for each of the three months ended September 30, 2018 and 2017 , and $0.4 million of tax credits for each of the nine months ended September 30, 2018 and 2017 . Contingencies/Litigation. From time to time, First Financial and its subsidiaries may be engaged in various matters of litigation, other assertions of improper or fraudulent loan practices or lending violations and other matters. Additionally, as part of the ordinary course of business, First Financial and its subsidiaries are parties to litigation involving claims to the ownership of funds in particular accounts, the collection of delinquent accounts, challenges to security interests in collateral and foreclosure interests that are incidental to our regular business activities. Reserves are established for these various matters of litigation, when appropriate, under FASB ASC Topic 450, Contingencies, based in part upon the advice of legal counsel. While the ultimate liability with respect to these other litigation matters and claims cannot be determined at this time, First Financial believes that damages, if any, and other amounts relating to pending matters are not probable or cannot be reasonably estimated as of September 30, 2018 . First Financial had no reserves related to litigation matters as of September 30, 2018 or December 31, 2017

INCOME TAXES

INCOME TAXES	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES For the third quarter 2018 , income tax expense was $12.9 million , resulting in an effective tax rate of 20.2% compared with income tax expense of $11.2 million and an effective tax rate of 31.1% for the comparable period in 2017. For the first nine months of 2018, income tax expense was $29.8 million , resulting in an effective tax rate of 20.2% compared with income tax expense of $32.9 million and an effective tax rate of 31.4% for the comparable period in 2017. On December 22, 2017, the Tax Cuts and Jobs Act was signed into law. As a result, First Financial valued its deferred tax assets and liabilities as well as its investments in affordable housing projects utilizing a 21% federal rate during the first nine months of 2018 compared to a 35% rate in the first nine months of 2017. At both September 30, 2018 and December 31, 2017 , First Financial had $2.9 million of unrecognized tax benefits, as determined in FASB ASC Topic 740-10, Income Taxes that, if recognized, would favorably affect the effective income tax rate in future periods. The unrecognized tax benefits relate to state income tax exposures from taking tax positions where the Company believes it is likely that, upon examination, a state may take a position contrary to the position taken by First Financial. The Company believes that resolution regarding our uncertain tax positions is reasonably possible within the next twelve months and could result in full, partial or no recognition of the benefit. First Financial recognizes interest accrued related to unrecognized tax benefits and penalties as income tax expense. At September 30, 2018 and December 31, 2017 , the Company had no interest or penalties recorded. First Financial and its subsidiaries are subject to U.S. federal income tax as well as state and local income tax in several jurisdictions. Tax years prior to 2014 have been closed and are no longer subject to U.S. federal income tax examinations. Tax years 2014 through 2017 remain open to examination by the federal taxing authority.

EMPLOYEE BENEFIT PLANS

EMPLOYEE BENEFIT PLANS	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
EMPLOYEE BENEFIT PLANS	EMPLOYEE BENEFIT PLANS First Financial sponsors a non-contributory defined benefit pension plan covering substantially all employees and uses a December 31 measurement date for the plan. Plan assets were primarily invested in fixed income and publicly traded equity mutual funds. The pension plan does not directly own any shares of First Financial common stock or any other First Financial security or product. First Financial made no cash contributions to fund the pension plan during the nine months ended September 30, 2018 , or the year ended December 31, 2017, and does not expect to make cash contributions to the plan through the remainder of 2018. As a result of the plan’s actuarial projections, which included consideration of the impact of the merger with MSFG, First Financial recorded expense of $0.3 million for the three months ended September 30, 2018 and $0.5 million for the nine months ended September 30, 2018 . Conversely, First Financial recorded income of $0.3 million for the three months ended September 30, 2017 and $1.0 million for the nine months ended September 30, 2017 . The following table sets forth information concerning amounts recognized in First Financial’s Consolidated Statements of Income related to the Company's pension plan: Three months ended Nine months ended September 30, September 30, (Dollars in thousands) 2018 2017 2018 2017 Service cost $ 1,736 $ 1,238 $ 4,766 $ 3,715 Interest cost 601 589 1,792 1,767 Expected return on assets (2,450 ) (2,481 ) (7,360 ) (7,443 ) Amortization of prior service cost (104 ) (103 ) (310 ) (310 ) Net actuarial loss 556 438 1,633 1,315 Net periodic benefit cost (income) $ 339 $ (319 ) $ 521 $ (956 )

REVENUE RECOGNITION

REVENUE RECOGNITION	9 Months Ended
	Sep. 30, 2018
Revenue Recognition [Abstract]
REVENUE RECOGNITION	REVENUE RECOGNITION On January 1, 2018, the Company adopted ASU No. 2014-09, Revenue from Contracts with Customers using the modified retrospective method applied to all contracts not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under the guidance set forth in this update while prior period amounts continue to be reported in accordance with legacy GAAP. Adoption of this update did not result in a change to the accounting for any of the in-scope revenue streams. As such, no cumulative effect adjustment to retained earnings was recorded. The majority of the Company's revenues come from interest income and other sources, including loans, leases, securities and derivatives, that are outside the scope of this guidance. The Company's services that fall within the scope of this ASU are presented within Noninterest income and are recognized as revenue as the Company satisfies its obligation to the customer. Services within the scope of this guidance include service charges on deposits, wealth management fees, bankcard income, investment brokerage fees and the sale of OREO. Service charges on deposit accounts. The Company 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 as that is the point in time the Company fulfills the customer's request. Account maintenance fees, which relate primarily to monthly maintenance, are earned over the course of a month, representing the period over which the Company satisfies the performance obligation. Similarly, overdraft fees are recognized at the point in time that the overdraft occurs as this corresponds with the Company's performance obligation. Service charges on deposit accounts are withdrawn from the customer's account balance. Trust and wealth management fees. Trust and wealth management fees are primarily asset-based, but can also include flat fees based upon a specific service rendered, such as tax preparation services. The Company’s performance obligation is generally satisfied over time and the resulting fees are recognized monthly, based upon the month-end market value of the assets under management and the applicable fees. The Company does not earn performance-based incentives. Optional services such as real estate sales and tax return preparation services are also available to existing trust and wealth management customers. The Company’s performance obligation for these transactional-based services is generally satisfied, and related revenue recognized, as incurred. Bankcard income. The Company earns interchange fees from cardholder transactions conducted through the Visa payment network. 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. Interchange income is presented on the Consolidated Statements of Income net of expenses. Gross interchange income for the third quarter of 2018 was $8.6 million , which was partially offset by $3.4 million of expenses within Noninterest income. Gross interchange income for the first nine months of 2018 was $22.1 million , which was partially offset by $8.1 million of expenses. Gain/loss on sale of OREO. The Company 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 the executed deed. When the Company finances the sale of OREO to the buyer, the Company assesses whether the buyer is committed to perform their obligations under the contract and whether collectibility 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. Other. Other noninterest income consists of other recurring revenue streams such as transaction fees, safe deposit rental income, insurance commissions, merchant referral income and brokerage revenue. Transaction fees primarily include check printing sales commissions, collection fees and wire transfer fees which arise from in-branch transactions. Safe deposit rental income arises from services charged to the customer on an annual basis and recognized upon receipt of payment. Insurance commissions are agent commissions earned by the Company and earned upon the effective date of the bound coverage. Merchant referral income is associated with a program whereby the Company receives a share of processing revenue that is generated from clients that were referred by First Financial to the service provider. Revenue is recognized at the point in time when the transaction occurs. Brokerage revenue represents fees from investment brokerage services provided to customers by a third party provider. The Company receives commissions from the third-party service provider on a monthly basis based upon customer activity for the month. The fees are recognized monthly and a receivable is recorded until commissions are paid the following month. Because the Company (i) acts as an agent in arranging the relationship between the customer and the third-party service provider and (ii) does not control the services rendered to the customers, investment brokerage fees are presented net of related costs.

EARNINGS PER COMMON SHARE

EARNINGS PER COMMON SHARE	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
EARNINGS PER COMMON SHARE	EARNINGS PER COMMON SHARE The following table sets forth the computation of basic and diluted earnings per share: Three months ended Nine months ended September 30, September 30, (Dollars in thousands, except per share data) 2018 2017 2018 2017 Numerator Net income available to common shareholders $ 50,657 $ 24,826 $ 117,581 $ 71,976 Denominator Basic earnings per common share - weighted average shares 97,411,201 61,577,619 85,602,116 61,507,160 Effect of dilutive securities Employee stock awards 536,760 552,774 515,566 617,128 Warrants 536,267 59,244 522,245 61,586 Diluted earnings per common share - adjusted weighted average shares 98,484,228 62,189,637 86,639,927 62,185,874 Earnings per share available to common shareholders Basic $ 0.52 $ 0.40 $ 1.37 $ 1.17 Diluted $ 0.51 $ 0.40 $ 1.36 $ 1.16 First Financial had two warrants outstanding to purchase the Company's common stock as of September 30, 2018 . The first warrant represents the right to purchase 17,172 shares of common stock at an exercise price of $12.09 per share, and expires in December 2018. The second warrant was acquired in the MSFG merger and represents the right to purchase 793,520 shares of First Financial's common stock at an exercise price of $10.71 per share and expires in January 2019. At September 30, 2017, First Financial had one warrant outstanding representing the right to purchase 105,832 shares of common stock. Stock options and warrants with exercise prices greater than the average market price of the common shares were not included in the computation of net income per diluted share, as they would have been antidilutive. Using the end of period price of the Company's common shares, there were no antidilutive options at September 30, 2018 and September 30, 2017

FAIR VALUE DISCLOSURES

FAIR VALUE DISCLOSURES	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
FAIR VALUE DISCLOSURES	FAIR VALUE DISCLOSURES The fair value framework as disclosed in the Fair Value Topic includes a hierarchy which focuses on prioritizing the inputs used in valuation techniques. The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets or liabilities (Level 1), a lower priority to observable inputs other than quoted prices in active markets for identical assets and liabilities (Level 2) and the lowest priority to unobservable inputs (Level 3). When determining the fair value measurements for assets and liabilities, First Financial looks to active markets to price identical assets or liabilities whenever possible and classifies such items in Level 1. When identical assets and liabilities are not traded in active markets, First Financial looks to observable market data for similar assets and liabilities and classifies such items as Level 2. Certain assets and liabilities are not actively traded in observable markets and First Financial must use alternative techniques, based on unobservable inputs, to determine the fair value and classifies such items as Level 3. The level within the fair value hierarchy is based on the lowest level of input that is significant in the fair value measurement. The estimated fair values of First Financial’s financial instruments not measured at fair value on a recurring or nonrecurring basis in the consolidated financial statements were as follows: Carrying Estimated fair value (Dollars in thousands) value Total Level 1 Level 2 Level 3 September 30, 2018 Financial assets Cash and short-term investments $ 222,277 $ 222,277 $ 222,277 $ 0 $ 0 Investment securities held-to-maturity 434,369 422,638 0 422,638 0 Other investments 115,757 N/A N/A N/A N/A Loans held for sale 13,277 13,277 0 13,277 0 Loans and leases 8,789,661 8,737,769 0 0 8,737,769 Accrued interest receivable 41,755 41,755 0 13,674 28,081 Financial liabilities Deposits 9,752,634 9,722,689 0 9,722,689 0 Short-term borrowings 1,294,252 1,294,252 1,294,252 0 0 Long-term debt 570,037 547,569 0 547,569 0 Accrued interest payable 10,517 10,517 2,963 7,554 0 Carrying Estimated fair value (Dollars in thousands) value Total Level 1 Level 2 Level 3 December 31, 2017 Financial assets Cash and short-term investments $ 184,624 $ 184,624 $ 184,624 $ 0 $ 0 Investment securities held-to-maturity 654,008 653,101 0 653,101 0 Other investments 53,140 N/A N/A N/A N/A Loans held for sale 11,502 11,502 0 11,502 0 Loans and leases 5,959,162 6,006,656 0 0 6,006,656 Accrued interest receivable 24,496 24,496 0 8,265 16,231 Financial liabilities Deposits 6,895,046 6,884,615 0 6,884,615 0 Short-term borrowings 814,565 814,565 814,565 0 0 Long-term debt 119,654 117,908 0 117,908 0 Accrued interest payable 5,104 5,104 204 4,900 0 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 our adoption of ASU 2016-01 in 2018, the methods utilized to measure the fair value of financial instruments at September 30, 2018 represent an approximation of exit price, however, an actual exit price may differ. The following methods, assumptions and valuation techniques were used by First Financial to measure different financial assets and liabilities at fair value on a recurring or nonrecurring basis. Investment securities. Investment securities classified as available-for-sale are recorded at fair value on a recurring basis. Fair value measurement is based upon quoted market prices, when available (Level 1). If quoted market prices are not available, fair values are measured utilizing independent valuation techniques of identical or similar investment securities. First Financial compiles prices from various sources who 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 the specific investment securities but rather relying on the investment securities’ relationship to other benchmark quoted investment securities. Any investment securities not valued based upon the methods previously described are considered Level 3. First Financial utilizes values provided by third-party pricing vendors to price the investment securities portfolio in accordance with the fair value hierarchy of the Fair Value Topic and reviews the pricing methodologies utilized by the pricing vendors to ensure that the fair value determination is consistent with the applicable accounting guidance. First Financial’s pricing process includes a series of quality assurance activities where prices are compared to recent market conditions, historical prices and other independent pricing services. Further, the Company periodically validates the fair value of a sample of securities in the portfolio by comparing the fair values to prices from other independent sources for the same or similar securities. First Financial analyzes unusual or significant variances, conducts additional research with the pricing vendor, and if necessary, takes appropriate action based on its findings. The results of the quality assurance process are incorporated into the selection of pricing providers by the portfolio manager. Impaired loans. The fair value of impaired loans are specifically reviewed for purposes of determining the appropriate amount of impairment to be allocated to the ALLL. Fair value is generally measured based on the value of the collateral securing the loans. Collateral may be in the form of real estate or business assets including equipment, inventory and accounts receivable. The value of real estate collateral is determined utilizing an income or market valuation approach based on an appraisal conducted by an independent, licensed third-party appraiser (Level 3). The value of business equipment is based on an outside appraisal, if deemed significant, or the net book value on the applicable borrower financial statements. Likewise, values for inventory and accounts receivable collateral are based on borrower financial statement balances or aging reports on a discounted basis as appropriate (Level 3). Impaired loans are measured at fair value on a nonrecurring basis. Any fair value adjustments are recorded in the period incurred as provision for loan and lease losses on the Consolidated Statements of Income. OREO. Assets acquired through loan foreclosure are recorded at fair value less costs to sell, with any difference between the fair value of the property and the carrying value of the loan recorded as a charge-off. If the fair value is higher than the carrying amount of the loan, the excess is recognized first as a recovery and then as noninterest income. Subsequent changes in value are reported as adjustments to the carrying amount and are recorded in noninterest expense. The carrying value of OREO is not re-measured to fair value on a recurring basis, but is subject to fair value adjustments when the carrying value differs from the fair value, less estimated selling costs. Fair value is based on recent real estate appraisals and is updated at least annually. The Company classifies OREO in level 3 of the fair value hierarchy. Derivatives. The fair values of derivative instruments are based primarily on a net present value calculation of the cash flows related to the interest rate swaps at the reporting date, using primarily observable market inputs such as interest rate yield curves which represents the cost to terminate the swap if First Financial should choose to do so. Additionally, First Financial utilizes an internally-developed model to value the credit risk component of derivative assets and liabilities, which is recorded as an adjustment to the fair value of the derivative asset or liability on the reporting date. Derivative instruments are classified as Level 2 in the fair value hierarchy. The financial assets and liabilities measured at fair value on a recurring basis in the consolidated financial statements were as follows: Fair value measurements using (Dollars in thousands) Level 1 Level 2 Level 3 Assets/liabilities at fair value September 30, 2018 Assets Derivatives $ 0 $ 33,806 $ 0 $ 33,806 Investment securities available-for-sale 95 2,626,631 0 2,626,726 Total $ 95 $ 2,660,437 $ 0 $ 2,660,532 Liabilities Derivatives $ 0 $ 33,321 $ 0 $ 33,321 Fair value measurements using (Dollars in thousands) Level 1 Level 2 Level 3 Assets/liabilities at fair value December 31, 2017 Assets Derivatives $ 0 $ 12,757 $ 0 $ 12,757 Investment securities available-for-sale 2,969 1,346,439 0 1,349,408 Total $ 2,969 $ 1,359,196 $ 0 $ 1,362,165 Liabilities Derivatives $ 0 $ 12,755 $ 0 $ 12,755 Certain financial assets and liabilities are measured at fair value on a nonrecurring basis. Adjustments to the fair market value of these assets usually result from the application of fair value accounting or write-downs of individual assets. The following table summarizes financial assets and liabilities measured at fair value on a nonrecurring basis. Fair value measurements using (Dollars in thousands) Level 1 Level 2 Level 3 September 30, 2018 Assets Impaired loans $ 0 $ 0 $ 2,816 OREO 0 0 1,515 Fair value measurements using (Dollars in thousands) Level 1 Level 2 Level 3 December 31, 2017 Assets Impaired loans $ 0 $ 0 $ 2,671 OREO 0 0 1,086

BUSINESS COMBINATIONS

BUSINESS COMBINATIONS	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
BUSINESS COMBINATIONS	BUSINESS COMBINATIONS On April 1, 2018, the Company completed its acquisition of MainSource Financial Group, Inc. and its banking subsidiary, MainSource Bank. Therefore, results of MSFG have been included in the results of operations beginning on April 1, 2018. Under the terms of the merger agreement, shareholders of MSFG received 1.3875 common shares of First Financial common stock for each share of MSFG common stock, with cash paid in lieu of fractional shares. Including outstanding options and warrants to purchase MSFG common stock, the total purchase consideration was $1.1 billion and resulted in goodwill of $676.9 million . The goodwill arising from the acquisition largely reflected synergies and cost savings resulting from combining the operations of the companies. First Financial incurred $33.3 million of merger related expenses related to the acquisition of MSFG during the nine months ended September 30, 2018. The acquisition is expected to provide additional revenue growth and diversification. The goodwill is not deductible for income tax purposes as the transaction was accounted for as a tax-free exchange. For further detail, see Note 6 – Goodwill and Other Intangible Assets. The MainSource transaction was accounted for using the acquisition method of accounting and accordingly, assets acquired, liabilities assumed and consideration exchanged were recorded at estimated fair value on the acquisition date, in accordance with FASB ASC Topic 805, Business Combinations. The fair value measurements of assets acquired and liabilities assumed are subject to refinement for up to one year after the closing date of the acquisition as additional information relative to closing date fair values become available. The Company continues to finalize the fair values of loans, intangible assets and liabilities. As a result, the fair value adjustments are preliminary and may change as information becomes available. Fair value adjustments will be finalized no later than April 2019. The following table provides the purchase price calculation as of the acquisition date, identifiable assets purchased and liabilities assumed at their estimated fair value. As a condition of the merger, certain acquired assets and liabilities held for sale were divested subsequent to the closing of the merger. There was no gain or loss recorded in the Consolidated Statement of Income in conjunction with this divestiture. (Dollars in thousands) MainSource Purchase consideration Cash consideration $ 43 Stock consideration 1,045,876 Warrant consideration 14,460 Options consideration 1,577 Total purchase consideration 1,061,956 Assets acquired Cash 71,734 Investment securities available-for-sale 901,008 Investment securities held-to-maturity 171,423 Other investments 28,763 Loans 2,792,517 Premises and equipment 98,537 Intangible assets 42,887 Other assets 169,311 Assets held for sale 127,775 Total assets acquired 4,403,955 Liabilities assumed Deposits 3,264,038 Subordinated notes 49,027 FHLB advances 291,887 Other borrowings 205,620 Other liabilities 32,654 Liabilities held for sale 175,722 Total liabilities assumed 4,018,948 Net identifiable assets 385,007 Goodwill $ 676,949 The following table presents supplemental pro forma information as if the acquisition had occurred at the beginning of 2017. The pro forma information includes adjustments for interest income on acquired loans, amortization of intangible assets arising from the transaction, depreciation expense on property acquired, interest expense on deposits acquired, merger-related expenses incurred and the related income tax effects. The pro forma financial information is not necessarily indicative of the results of operations that would have occurred had the transactions been effected on the assumed date. The disclosures regarding the results of operations for MSFG subsequent to its acquisition date are omitted as this information is not practical to obtain. Nine months ended September 30, (Dollars in thousands, except per share data) 2018 2017 Pro Forma Condensed Combined Income Statement Information Net interest income $ 362,112 $ 334,736 Net income 161,323 93,293 Basic earnings per share 1.66 0.96 Diluted earnings per share 1.64 0.95

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2018
Off-Balance-Sheet Credit Exposure, Policy [Policy Text Block]	Letters of credit are conditional commitments issued by First Financial to guarantee the performance of a client to a third party.  First Financial’s portfolio of letters of credit consists primarily of performance assurances made on behalf of clients who have a contractual commitment to produce or deliver goods or services.  The risk to First Financial arises from its obligation to make payment in the event of the client's contractual default to produce the contracted good or service to a third party.
Basis of Presentation Policy	The Consolidated Financial Statements of First Financial Bancorp., a financial holding company principally serving Ohio, Indiana, Kentucky and Illinois, include the accounts and operations of First Financial and its wholly-owned subsidiary, First Financial Bank. All significant intercompany transactions and accounts have been eliminated in consolidation.  Certain reclassifications of prior periods' amounts have been made to conform to current year presentation. Such reclassifications had no effect on net earnings.
Use of Estimates, Policy	The preparation of financial statements in conformity with GAAP requires management to make estimates, assumptions and judgments that affect the amounts reported in the Consolidated Financial Statements and accompanying Notes. These estimates, assumptions and judgments are inherently subjective and may be susceptible to significant change. Actual realized amounts could differ materially from these estimates.
Loans and Leases Receivable, Past Due Status, Policy	Loans are considered past due or delinquent when the contractual principal or interest due in accordance with the terms of the loan agreement remains unpaid after the date of the scheduled payment.
Loans and Leases Receivable, Nonaccrual Loan and Lease Status, Policy	Loans are classified as nonaccrual when, in the opinion of management, collection of principal or interest is doubtful or when principal or interest payments are 90 days or more past due. Generally, loans are classified as nonaccrual due to the continued failure by the borrower to adhere to contractual payment terms, coupled with other pertinent factors. When a loan is classified as nonaccrual, the accrual of interest income is discontinued and previously accrued but unpaid interest is reversed. Any payments received while a loan is on nonaccrual status are applied as a reduction to the carrying value of the loan. A loan classified as nonaccrual may return to accrual status if collection of future principal and interest payments is no longer doubtful. Purchased impaired loans are classified as performing, even though they may be contractually past due, as any nonpayment of contractual principal or interest is considered in the periodic re-estimation of expected cash flows and is included in the resulting recognition of current period provision for loan and lease losses or prospective yield adjustments.
Loans and Leases Receivable, Troubled Debt Restructuring Policy	A loan modification is considered a TDR when the borrower is experiencing financial difficulty and concessions are made by the Company that would not otherwise be considered for a borrower with similar credit characteristics. The most common types of modifications include interest rate reductions, maturity extensions and modifications to principal amortization, including interest-only structures. Modified terms are dependent upon the financial position and needs of the individual borrower. If the modification agreement is violated, the loan is managed by the Company’s credit administration group for resolution, which may result in foreclosure in the case of real estate.
Impaired Financing Receivable, Policy	First Financial individually reviews all impaired commercial loan relationships, as well as consumer loan TDRs, greater than $250,000
Loans and Leases Receivable, Real Estate Acquired Through Foreclosure, Policy	OREO consists of properties acquired by the Company primarily through the loan foreclosure or repossession process, that results in partial or total satisfaction of problem loans.
Loans and Leases Receivable, Allowance for Loan Losses Policy	Management maintains the ALLL at a level that it considers sufficient to absorb probable incurred loan and lease losses inherent in the portfolio. Management determines the adequacy of the ALLL based on historical loss experience as well as other significant factors such as composition of the portfolio, economic conditions, geographic footprint, the results of periodic internal and external evaluations of delinquent, nonaccrual and classified loans and any other adverse situations that may affect a specific borrower's ability to repay, including the timing of future payments.
Goodwill and Intangible Assets, Goodwill, Policy	Assets and liabilities acquired in a business combination are recorded at their estimated fair values as of the acquisition date. The excess cost of the acquisition over the fair value of net assets acquired is recorded as goodwill.
Goodwill and Intangible Assets, Goodwill Impairment Policy	Goodwill is evaluated for impairment on an annual basis as of October 1 of each year, or whenever events or changes in circumstances indicate that the fair value of a reporting unit may be below its carrying value.
Goodwill and Intangible Assets, Policy	Core deposit intangibles represent the estimated fair value of acquired customer deposit relationships on the date of acquisition and are amortized on an accelerated basis
Income Tax, Policy	The unrecognized tax benefits relate to state income tax exposures from taking tax positions where the Company believes it is likely that, upon examination, a state may take a position contrary to the position taken by First Financial.
Commitments and Contingencies, Policy	First Financial offers a variety of financial instruments including standby letters of credit and outstanding commitments to extend credit to assist clients in meeting their requirement for liquidity and credit enhancement. GAAP does not require these financial instruments to be recorded in the Consolidated Financial Statements.
Fair Value Measurement, Policy [Policy Text Block]	The fair value framework as disclosed in the Fair Value Topic includes a hierarchy which focuses on prioritizing the inputs used in valuation techniques. The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets or liabilities (Level 1), a lower priority to observable inputs other than quoted prices in active markets for identical assets and liabilities (Level 2) and the lowest priority to unobservable inputs (Level 3). When determining the fair value measurements for assets and liabilities, First Financial looks to active markets to price identical assets or liabilities whenever possible and classifies such items in Level 1. When identical assets and liabilities are not traded in active markets, First Financial looks to observable market data for similar assets and liabilities and classifies such items as Level 2. Certain assets and liabilities are not actively traded in observable markets and First Financial must use alternative techniques, based on unobservable inputs, to determine the fair value and classifies such items as Level 3. The level within the fair value hierarchy is based on the lowest level of input that is significant in the fair value measurement.
Fair Value of Financial Instruments, Policy	The following methods, assumptions and valuation techniques were used by First Financial to measure different financial assets and liabilities at fair value on a recurring or nonrecurring basis. Investment securities. Investment securities classified as available-for-sale are recorded at fair value on a recurring basis. Fair value measurement is based upon quoted market prices, when available (Level 1). If quoted market prices are not available, fair values are measured utilizing independent valuation techniques of identical or similar investment securities. First Financial compiles prices from various sources who 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 the specific investment securities but rather relying on the investment securities’ relationship to other benchmark quoted investment securities. Any investment securities not valued based upon the methods previously described are considered Level 3. First Financial utilizes values provided by third-party pricing vendors to price the investment securities portfolio in accordance with the fair value hierarchy of the Fair Value Topic and reviews the pricing methodologies utilized by the pricing vendors to ensure that the fair value determination is consistent with the applicable accounting guidance. First Financial’s pricing process includes a series of quality assurance activities where prices are compared to recent market conditions, historical prices and other independent pricing services. Further, the Company periodically validates the fair value of a sample of securities in the portfolio by comparing the fair values to prices from other independent sources for the same or similar securities. First Financial analyzes unusual or significant variances, conducts additional research with the pricing vendor, and if necessary, takes appropriate action based on its findings. The results of the quality assurance process are incorporated into the selection of pricing providers by the portfolio manager. Impaired loans. The fair value of impaired loans are specifically reviewed for purposes of determining the appropriate amount of impairment to be allocated to the ALLL. Fair value is generally measured based on the value of the collateral securing the loans. Collateral may be in the form of real estate or business assets including equipment, inventory and accounts receivable. The value of real estate collateral is determined utilizing an income or market valuation approach based on an appraisal conducted by an independent, licensed third-party appraiser (Level 3). The value of business equipment is based on an outside appraisal, if deemed significant, or the net book value on the applicable borrower financial statements. Likewise, values for inventory and accounts receivable collateral are based on borrower financial statement balances or aging reports on a discounted basis as appropriate (Level 3). Impaired loans are measured at fair value on a nonrecurring basis. Any fair value adjustments are recorded in the period incurred as provision for loan and lease losses on the Consolidated Statements of Income. OREO. Assets acquired through loan foreclosure are recorded at fair value less costs to sell, with any difference between the fair value of the property and the carrying value of the loan recorded as a charge-off. If the fair value is higher than the carrying amount of the loan, the excess is recognized first as a recovery and then as noninterest income. Subsequent changes in value are reported as adjustments to the carrying amount and are recorded in noninterest expense. The carrying value of OREO is not re-measured to fair value on a recurring basis, but is subject to fair value adjustments when the carrying value differs from the fair value, less estimated selling costs. Fair value is based on recent real estate appraisals and is updated at least annually. The Company classifies OREO in level 3 of the fair value hierarchy. Derivatives.
Loan Commitments, Policy [Policy Text Block]	Loan commitments are agreements to extend credit to a client, absent any violation of conditions established in the commitment agreement.  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 amount of collateral obtained, if deemed necessary by First Financial upon extension of credit, is based on management’s credit evaluation of the client.  The collateral held varies, but may include securities, real estate, inventory, plant or equipment.
Other Contract-Mortgage
Derivatives, Methods of Accounting, Hedging Derivatives, Policy	First Financial enters into IRLCs and forward commitments for the future delivery of mortgage loans to third party investors, which are considered derivatives. When borrowers secure an IRLC with First Financial and the loan is intended to be sold, First Financial will enter into forward commitments for the future delivery of the loans to third party investors in order to hedge against the effect of changes in interest rates impacting IRLCs and loans held for sale.
Credit Risk
Derivatives, Methods of Accounting, Hedging Derivatives, Policy	First Financial manages market value credit risk through counterparty credit policies, which require the Company to maintain a total derivative notional position of less than 35% of assets, total credit exposure of less than 3% of capital and no single counterparty credit risk exposure greater than $20.0 million
Fair Value Hedges
Derivatives, Methods of Accounting, Hedging Derivatives, Policy	First Financial utilizes interest rate swaps as a means to offer commercial borrowers fixed rate funding while providing the Company with floating rate assets.

INVESTMENTS (Tables)

INVESTMENTS (Tables)	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Summary of Held-To-Maturity and Available-For-Sale Investment Securities	The following is a summary of HTM and AFS investment securities as of September 30, 2018 : Held-to-maturity Available-for-sale (Dollars in thousands) Amortized Unrecognized gain Unrecognized loss Fair Amortized cost Unrealized gain Unrealized loss Fair U.S. Treasuries $ 0 $ 0 $ 0 $ 0 $ 99 $ 0 $ (4 ) $ 95 Securities of U.S. government agencies and corporations 0 0 0 0 33,438 7 (600 ) 32,845 Mortgage-backed securities - residential 26,603 0 (1,615 ) 24,988 581,657 551 (14,262 ) 567,946 Mortgage-backed securities - commercial 150,223 0 (6,378 ) 143,845 362,874 118 (5,646 ) 357,346 Collateralized mortgage obligations 13,182 0 (727 ) 12,455 864,824 940 (15,436 ) 850,328 Obligations of state and other political subdivisions 244,361 275 (3,286 ) 241,350 247,206 1,533 (2,626 ) 246,113 Asset-backed securities 0 0 0 0 490,685 582 (1,499 ) 489,768 Other securities 0 0 0 0 81,546 1,039 (300 ) 82,285 Total $ 434,369 $ 275 $ (12,006 ) $ 422,638 $ 2,662,329 $ 4,770 $ (40,373 ) $ 2,626,726 The following is a summary of held-to-maturity and available-for-sale investment securities as of December 31, 2017 : Held-to-maturity Available-for-sale (Dollars in thousands) Amortized Unrecognized gain Unrecognized Fair Amortized Unrealized Unrealized Fair U.S. Treasuries $ 0 $ 0 $ 0 $ 0 $ 98 $ 0 $ (1 ) $ 97 Securities of U.S. government agencies and corporations 11,168 0 (76 ) 11,092 15,695 220 0 15,915 Mortgage-backed securities - residential 162,093 2,042 (1,535 ) 162,600 290,793 849 (2,599 ) 289,043 Mortgage-backed securities - commercial 255,027 1,372 (3,000 ) 253,399 150,356 164 (1,417 ) 149,103 Collateralized mortgage obligations 143,545 354 (1,602 ) 142,297 306,095 1,158 (1,861 ) 305,392 Obligations of state and other political subdivisions 82,175 1,804 (266 ) 83,713 124,269 2,162 (676 ) 125,755 Asset-backed securities 0 0 0 0 377,655 1,628 (306 ) 378,977 Other securities 0 0 0 0 83,266 2,147 (287 ) 85,126 Total $ 654,008 $ 5,572 $ (6,479 ) $ 653,101 $ 1,348,227 $ 8,328 $ (7,147 ) $ 1,349,408
Summary of Investment Securities by Estimated Maturity	The following table provides a summary of investment securities by contractual maturity as of September 30, 2018 , except for residential and commercial mortgage-backed securities, collateralized mortgage obligations and asset-backed securities, which are shown as single totals due to the unpredictability of the timing in principal repayments. Held-to-maturity Available-for-sale (Dollars in thousands) Amortized cost Fair value Amortized cost Fair value By Contractual Maturity: Due in one year or less $ 0 $ 0 $ 3,932 $ 3,922 Due after one year through five years 275 277 72,831 72,633 Due after five years through ten years 18,337 18,274 138,584 139,591 Due after ten years 225,749 222,799 146,942 145,192 Mortgage-backed securities - residential 26,603 24,988 581,657 567,946 Mortgage-backed securities - commercial 150,223 143,845 362,874 357,346 Collateralized mortgage obligations 13,182 12,455 864,824 850,328 Asset-backed securities 0 0 490,685 489,768 Total $ 434,369 $ 422,638 $ 2,662,329 $ 2,626,726
Age of Gross Unrealized Losses and Associated Fair Value by Investment Category	The following tables provide the fair value and gross unrealized losses on investment securities in an unrealized loss position, aggregated by investment category and the length of time the individual securities have been in a continuous loss position: September 30, 2018 Less than 12 months 12 months or more Total (Dollars in thousands) Fair value Unrealized loss Fair Unrealized Fair Unrealized U.S. Treasuries $ 0 $ 0 $ 95 $ (4 ) $ 95 $ (4 ) Securities of U.S. Government agencies and corporations 19,546 (411 ) 5,332 (189 ) 24,878 (600 ) Mortgage-backed securities - residential 431,332 (8,695 ) 141,519 (7,182 ) 572,851 (15,877 ) Mortgage-backed securities - commercial 281,842 (3,637 ) 151,185 (8,387 ) 433,027 (12,024 ) Collateralized mortgage obligations 658,749 (10,407 ) 133,153 (5,756 ) 791,902 (16,163 ) Obligations of state and other political subdivisions 304,298 (3,976 ) 37,683 (1,936 ) 341,981 (5,912 ) Asset-backed securities 206,708 (1,125 ) 20,776 (374 ) 227,484 (1,499 ) Other securities 17,901 (192 ) 4,678 (108 ) 22,579 (300 ) Total $ 1,920,376 $ (28,443 ) $ 494,421 $ (23,936 ) $ 2,414,797 $ (52,379 ) December 31, 2017 Less than 12 months 12 months or more Total Fair Unrealized Fair Unrealized Fair Unrealized (Dollars in thousands) value loss value loss value loss U.S. Treasuries $ 97 $ (1 ) $ 0 $ 0 $ 97 $ (1 ) Securities of U.S. Government agencies and corporations 11,092 (76 ) 0 0 11,092 (76 ) Mortgage-backed securities - residential 175,183 (1,109 ) 108,782 (3,025 ) 283,965 (4,134 ) Mortgage-backed securities - commercial 132,818 (1,713 ) 72,139 (2,704 ) 204,957 (4,417 ) Collateralized mortgage obligations 164,909 (1,138 ) 101,436 (2,325 ) 266,345 (3,463 ) Obligations of state and other political subdivisions 38,450 (507 ) 21,639 (435 ) 60,089 (942 ) Asset-backed securities 44,941 (200 ) 24,396 (106 ) 69,337 (306 ) Other securities 2,605 (1 ) 7,124 (286 ) 9,729 (287 ) Total $ 570,095 $ (4,745 ) $ 335,516 $ (8,881 ) $ 905,611 $ (13,626 )

LOANS AND LEASES (Tables)

LOANS AND LEASES (Tables)	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Commercial and Consumer Credit Exposure by Risk Attribute	Commercial and consumer credit exposure by risk attribute was as follows: As of September 30, 2018 Commercial Real Estate Lease (Dollars in thousands) & industrial Construction Commercial financing Total Pass $ 2,335,925 $ 552,973 $ 3,757,627 $ 92,551 $ 6,739,076 Special Mention 39,060 12,094 49,463 0 100,617 Substandard 51,605 10 61,053 2,766 115,434 Doubtful 0 0 0 0 0 Total $ 2,426,590 $ 565,077 $ 3,868,143 $ 95,317 $ 6,955,127 (Dollars in thousands) Residential real estate Home equity Installment Credit card Total Performing $ 919,440 $ 809,653 $ 97,097 $ 45,741 $ 1,871,931 Nonperforming 13,522 6,480 316 0 20,318 Total $ 932,962 $ 816,133 $ 97,413 $ 45,741 $ 1,892,249 As of December 31, 2017 Commercial Real Estate Lease (Dollars in thousands) & industrial Construction Commercial financing Total Pass $ 1,882,464 $ 467,687 $ 2,446,999 $ 88,078 $ 4,885,228 Special Mention 6,226 0 4,436 0 10,662 Substandard 24,053 43 38,656 1,269 64,021 Doubtful 0 0 0 0 0 Total $ 1,912,743 $ 467,730 $ 2,490,091 $ 89,347 $ 4,959,911 (Dollars in thousands) Residential real estate Home equity Installment Credit card Total Performing $ 463,459 $ 489,148 $ 41,331 $ 46,691 $ 1,040,629 Nonperforming 7,932 4,456 255 0 12,643 Total $ 471,391 $ 493,604 $ 41,586 $ 46,691 $ 1,053,272
Loan Delinquency, including Nonaccrual Loans	Loan delinquency, including loans classified as nonaccrual, was as follows: As of September 30, 2018 (Dollars in thousands) 30 – 59 60 – 89 > 90 days Total Current Subtotal Purchased impaired Total > 90 days Loans Commercial & industrial $ 1,991 $ 1,613 $ 2,662 $ 6,266 $ 2,414,484 $ 2,420,750 $ 5,840 $ 2,426,590 $ 0 Lease financing 0 0 0 0 95,317 95,317 0 95,317 0 Construction real estate 283 0 0 283 564,535 564,818 259 565,077 0 Commercial real estate 4,513 407 16,296 21,216 3,789,238 3,810,454 57,689 3,868,143 0 Residential real estate 2,796 1,828 2,825 7,449 888,367 895,816 37,146 932,962 0 Home equity 3,435 1,336 3,153 7,924 804,670 812,594 3,539 816,133 0 Installment 201 21 282 504 96,360 96,864 549 97,413 0 Credit card 301 179 144 624 45,117 45,741 0 45,741 144 Total $ 13,520 $ 5,384 $ 25,362 $ 44,266 $ 8,698,088 $ 8,742,354 $ 105,022 $ 8,847,376 $ 144 As of December 31, 2017 (Dollars in thousands) 30 – 59 60 – 89 > 90 days Total Current Subtotal Purchased impaired Total > 90 days Loans Commercial & industrial $ 755 $ 1,657 $ 5,078 $ 7,490 $ 1,901,821 $ 1,909,311 $ 3,432 $ 1,912,743 $ 0 Lease financing 485 0 0 485 88,862 89,347 0 89,347 0 Construction real estate 234 0 0 234 467,216 467,450 280 467,730 0 Commercial real estate 1,716 201 8,777 10,694 2,419,969 2,430,663 59,428 2,490,091 0 Residential real estate 526 811 1,992 3,329 430,500 433,829 37,562 471,391 0 Home equity 2,716 394 1,753 4,863 485,127 489,990 3,614 493,604 0 Installment 179 29 205 413 40,529 40,942 644 41,586 0 Credit card 285 87 62 434 46,257 46,691 0 46,691 62 Total $ 6,896 $ 3,179 $ 17,867 $ 27,942 $ 5,880,281 $ 5,908,223 $ 104,960 $ 6,013,183 $ 62
Loans Restructured During Period	The following tables provide information on loan modifications classified as TDRs during the three and nine months ended September 30, 2018 and 2017 : Three months ended September 30, 2018 September 30, 2017 (Dollars in thousands) Number of loans Pre-modification loan balance Period end balance Number of loans Pre-modification loan balance Period end balance Commercial & industrial 0 $ 0 $ 0 1 $ 45 $ 37 Construction real estate 0 0 0 0 0 0 Commercial real estate 0 0 0 1 285 285 Residential real estate 1 148 143 6 416 315 Home equity 1 10 10 1 39 39 Installment 0 0 0 0 0 0 Total 2 $ 158 $ 153 9 $ 785 $ 676 Nine months ended September 30, 2018 September 30, 2017 (Dollars in thousands) Number of loans Pre-modification loan balance Period end balance Number of loans Pre-modification loan balance Period end balance Commercial & industrial 12 $ 7,149 $ 7,096 7 $ 5,724 $ 5,661 Construction real estate 0 0 0 0 0 0 Commercial real estate 6 2,119 2,088 7 1,791 1,734 Residential real estate 4 442 437 6 416 315 Home equity 1 10 10 1 39 39 Installment 0 0 0 0 0 0 Total 23 $ 9,720 $ 9,631 21 $ 7,970 $ 7,749
Loans Restructured, Modifications	The following table provides information on how TDRs were modified during the three and nine months ended September 30, 2018 and 2017 : Three months ended Nine months ended September 30, September 30, (Dollars in thousands) 2018 2017 2018 2017 Extended maturities $ 143 $ 0 $ 3,031 $ 3,261 Adjusted interest rates 0 0 52 2,767 Combination of rate and maturity changes 0 285 0 465 Forbearance 0 354 6,199 1,181 Other (1) 10 37 349 75 Total $ 153 $ 676 $ 9,631 $ 7,749 (1) Includes covenant modifications and other concessions, or combination of concessions, that do not consist of interest rate adjustments, forbearance and maturity extensions
Nonaccrual, Restructured and Impaired Loans	The following table provides information on impaired loans, excluding purchased impaired loans: (Dollars in thousands) September 30, 2018 December 31, 2017 Impaired loans Nonaccrual loans (1) Commercial & industrial $ 4,310 $ 5,229 Lease financing 0 82 Construction real estate 10 29 Commercial real estate 20,338 10,616 Residential real estate 11,365 4,140 Home equity 6,018 3,743 Installment 327 243 Nonaccrual loans 42,368 24,082 Accruing troubled debt restructurings 20,313 17,545 Total impaired loans $ 62,681 $ 41,627 (1) Nonaccrual loans include nonaccrual TDRs of $4.7 million and $6.4 million as of September 30, 2018 and December 31, 2017 , respectively. Three months ended Nine months ended September 30, September 30, (Dollars in thousands) 2018 2017 2018 2017 Interest income effect on impaired loans Gross amount of interest that would have been recorded under original terms $ 1,192 $ 761 $ 3,126 $ 2,735 Interest included in income Nonaccrual loans 169 140 395 445 Troubled debt restructurings 187 168 500 563 Total interest included in income 356 308 895 1,008 Net impact on interest income $ 836 $ 453 $ 2,231 $ 1,727
Investment in Impaired Loans	First Financial's investment in impaired loans was as follows: As of September 30, 2018 As of December 31, 2017 (Dollars in thousands) Current balance Contractual principal balance Related allowance Current balance Contractual Related Loans with no related allowance recorded Commercial & industrial $ 9,209 $ 13,034 $ 0 $ 7,162 $ 8,460 $ 0 Lease financing 0 0 0 82 82 0 Construction real estate 10 27 0 29 60 0 Commercial real estate 26,722 32,706 0 18,423 20,837 0 Residential real estate 14,277 17,083 0 6,876 8,145 0 Home equity 6,554 7,337 0 4,356 5,399 0 Installment 332 639 0 255 422 0 Total 57,104 70,826 0 37,183 43,405 0 Loans with an allowance recorded Commercial & industrial 2,776 2,776 1,562 169 169 169 Lease financing 0 0 0 0 0 0 Construction real estate 0 0 0 0 0 0 Commercial real estate 1,668 2,322 66 3,119 3,120 448 Residential real estate 1,033 1,033 160 1,056 1,063 160 Home equity 100 100 2 100 100 2 Installment 0 0 0 0 0 0 Total 5,577 6,231 1,790 4,444 4,452 779 Total Commercial & industrial 11,985 15,810 1,562 7,331 8,629 169 Lease financing 0 0 0 82 82 0 Construction real estate 10 27 0 29 60 0 Commercial real estate 28,390 35,028 66 21,542 23,957 448 Residential real estate 15,310 18,116 160 7,932 9,208 160 Home equity 6,654 7,437 2 4,456 5,499 2 Installment 332 639 0 255 422 0 Total $ 62,681 $ 77,057 $ 1,790 $ 41,627 $ 47,857 $ 779 First Financial's average impaired loans by class and interest income recognized by class was as follows: Three months ended September 30, 2018 September 30, 2017 (Dollars in thousands) Average Interest Average Interest Loans with no related allowance recorded Commercial & industrial $ 10,033 $ 63 $ 13,730 $ 63 Lease financing 0 0 91 1 Construction real estate 17 0 950 0 Commercial real estate 28,689 136 23,187 147 Residential real estate 13,247 86 7,569 55 Home equity 6,463 31 3,791 26 Installment 318 1 290 1 Total 58,767 317 49,608 293 Loans with an allowance recorded Commercial & industrial 1,578 28 1,832 2 Lease financing 0 0 0 0 Construction real estate 0 0 0 0 Commercial real estate 1,012 3 652 5 Residential real estate 1,036 7 1,067 7 Home equity 100 1 101 1 Installment 0 0 0 0 Total 3,726 39 3,652 15 Total Commercial & industrial 11,611 91 15,562 65 Lease financing 0 0 91 1 Construction real estate 17 0 950 0 Commercial real estate 29,701 139 23,839 152 Residential real estate 14,283 93 8,636 62 Home equity 6,563 32 3,892 27 Installment 318 1 290 1 Total $ 62,493 $ 356 $ 53,260 $ 308 Nine months ended September 30, 2018 September 30, 2017 (Dollars in thousands) Average Interest Average Interest Loans with no related allowance recorded Commercial & industrial $ 8,950 $ 162 $ 14,669 $ 259 Lease financing 21 0 120 3 Construction real estate 22 2 744 0 Commercial real estate 25,044 375 21,563 451 Residential real estate 9,875 209 7,801 147 Home equity 5,339 78 3,951 77 Installment 299 2 351 4 Total 49,550 828 49,199 941 Loans with an allowance recorded Commercial & industrial 891 34 1,463 26 Lease financing 0 0 0 0 Construction real estate 0 0 0 0 Commercial real estate 1,376 9 2,513 18 Residential real estate 1,043 21 1,126 20 Home equity 100 3 101 3 Installment 0 0 0 0 Total 3,410 67 5,203 67 Total Commercial & industrial 9,841 196 16,132 285 Lease financing 21 0 120 3 Construction real estate 22 2 744 0 Commercial real estate 26,420 384 24,076 469 Residential real estate 10,918 230 8,927 167 Home equity 5,439 81 4,052 80 Installment 299 2 351 4 Total $ 52,960 $ 895 $ 54,402 $ 1,008
Changes in Other Real Estate Owned	Changes in OREO were as follows: Three months ended Nine months ended September 30, September 30, (Dollars in thousands) 2018 2017 2018 2017 Balance at beginning of period $ 1,853 $ 5,961 $ 2,781 $ 6,284 Additions Commercial & industrial 79 1,559 1,269 1,731 Residential real estate 739 235 1,723 2,313 Total additions 818 1,794 2,992 4,044 Disposals Commercial & industrial (181 ) (3,684 ) (2,611 ) (5,291 ) Residential real estate (117 ) (821 ) (527 ) (1,506 ) Total disposals (298 ) (4,505 ) (3,138 ) (6,797 ) Valuation adjustment Commercial & industrial (258 ) (102 ) (355 ) (264 ) Residential real estate (197 ) (32 ) (362 ) (151 ) Total valuation adjustment (455 ) (134 ) (717 ) (415 ) Balance at end of period $ 1,918 $ 3,116 $ 1,918 $ 3,116

ALLOWANCE FOR LOAN AND LEASE _2

ALLOWANCE FOR LOAN AND LEASE LOSSES (Tables)	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Allowance for Loan and Lease Losses by Classification	Changes in the ALLL by loan category were as follows: Three months ended September 30, 2018 Real Estate (Dollars in thousands) Commercial and industrial Lease financing Construction Commercial Residential Home Equity Installment Credit card Total Allowance for loan and lease losses: Balance at beginning of period $ 17,528 $ 797 $ 3,985 $ 20,511 $ 4,668 $ 4,801 $ 290 $ 1,496 $ 54,076 Provision for loan and lease losses 2,035 287 (114 ) 959 50 63 (288 ) 246 3,238 Gross charge-offs (232 ) 0 0 (902 ) (145 ) (351 ) (43 ) (390 ) (2,063 ) Recoveries 627 0 146 786 71 419 351 64 2,464 Total net charge-offs 395 0 146 (116 ) (74 ) 68 308 (326 ) 401 Ending allowance for loan and lease losses $ 19,958 $ 1,084 $ 4,017 $ 21,354 $ 4,644 $ 4,932 $ 310 $ 1,416 $ 57,715 Three months ended September 30, 2017 Real Estate (Dollars in thousands) Commercial and industrial Lease financing Construction Commercial Residential Home Equity Installment Credit card Total Allowance for loan and lease losses: Balance at beginning of period $ 18,313 $ 550 $ 3,416 $ 21,717 $ 5,016 $ 4,138 $ 355 $ 1,368 $ 54,873 Provision for loan and lease losses 3,024 507 (178 ) (1,003 ) (243 ) 819 (80 ) 107 2,953 Loans charged off (4,122 ) 0 0 (58 ) (23 ) (71 ) (24 ) (201 ) (4,499 ) Recoveries 325 0 0 585 70 110 74 43 1,207 Total net charge-offs (3,797 ) 0 0 527 47 39 50 (158 ) (3,292 ) Ending allowance for loan and lease losses $ 17,540 $ 1,057 $ 3,238 $ 21,241 $ 4,820 $ 4,996 $ 325 $ 1,317 $ 54,534 Nine months ended September 30, 2018 Real Estate (Dollars in thousands) Commercial & industrial Lease financing Construction Commercial Residential Home equity Installment Credit card Total Allowance for loan and lease losses: Balance at beginning of period $ 17,598 $ 675 $ 3,577 $ 20,930 $ 4,683 $ 4,935 $ 307 $ 1,316 $ 54,021 Provision for loan and lease losses 6,252 408 294 1,155 136 (60 ) (201 ) 1,292 9,276 Loans charged off (5,473 ) 0 0 (3,156 ) (342 ) (978 ) (277 ) (1,328 ) (11,554 ) Recoveries 1,581 1 146 2,425 167 1,035 481 136 5,972 Total net charge-offs (3,892 ) 1 146 (731 ) (175 ) 57 204 (1,192 ) (5,582 ) Ending allowance for loan and lease losses $ 19,958 $ 1,084 $ 4,017 $ 21,354 $ 4,644 $ 4,932 $ 310 $ 1,416 $ 57,715 Nine months ended September 30, 2017 Real Estate (Dollars in thousands) Commercial & industrial Lease financing Construction Commercial Residential Home equity Installment Credit card Total Allowance for loan and lease losses: Balance at beginning of period $ 19,225 $ 716 $ 3,282 $ 26,540 $ 3,208 $ 3,043 $ 388 $ 1,559 $ 57,961 Provision for loan and lease losses 5,965 340 (133 ) (6,510 ) 1,781 2,150 (52 ) 246 3,787 Loans charged off (8,930 ) 0 0 (1,028 ) (307 ) (635 ) (199 ) (648 ) (11,747 ) Recoveries 1,280 1 89 2,239 138 438 188 160 4,533 Total net charge-offs (7,650 ) 1 89 1,211 (169 ) (197 ) (11 ) (488 ) (7,214 ) Ending allowance for loan and lease losses $ 17,540 $ 1,057 $ 3,238 $ 21,241 $ 4,820 $ 4,996 $ 325 $ 1,317 $ 54,534 As of December 31, 2017 Real Estate (Dollars in thousands) Commercial & industrial Lease financing Construction Commercial Residential Home equity Installment Credit card Total Ending allowance balance attributable to loans Individually evaluated for impairment $ 169 $ 0 $ 0 $ 448 $ 160 $ 2 $ 0 $ 0 $ 779 Collectively evaluated for impairment 17,429 675 3,577 20,482 4,523 4,933 307 1,316 53,242 Ending allowance for loan and lease losses $ 17,598 $ 675 $ 3,577 $ 20,930 $ 4,683 $ 4,935 $ 307 $ 1,316 $ 54,021 Loans Individually evaluated for impairment $ 7,331 $ 82 $ 29 $ 21,542 $ 7,932 $ 4,456 $ 255 $ 0 $ 41,627 Collectively evaluated for impairment 1,905,412 89,265 467,701 2,468,549 463,459 489,148 41,331 46,691 5,971,556 Total loans $ 1,912,743 $ 89,347 $ 467,730 $ 2,490,091 $ 471,391 $ 493,604 $ 41,586 $ 46,691 $ 6,013,183 As of September 30, 2018 Real Estate (Dollars in thousands) Commercial & industrial Lease financing Construction Commercial Residential Home equity Installment Credit card Total Ending allowance balance attributable to loans Individually evaluated for impairment $ 1,562 $ 0 $ 0 $ 66 $ 160 $ 2 $ 0 $ 0 $ 1,790 Collectively evaluated for impairment 18,396 1,084 4,017 21,288 4,484 4,930 310 1,416 55,925 Ending allowance for loan and lease losses $ 19,958 $ 1,084 $ 4,017 $ 21,354 $ 4,644 $ 4,932 $ 310 $ 1,416 $ 57,715 Loans Individually evaluated for impairment $ 11,985 $ 0 $ 10 $ 28,390 $ 15,310 $ 6,654 $ 332 $ 0 $ 62,681 Collectively evaluated for impairment 2,414,605 95,317 565,067 3,839,753 917,652 809,479 97,081 45,741 8,784,695 Total loans $ 2,426,590 $ 95,317 $ 565,077 $ 3,868,143 $ 932,962 $ 816,133 $ 97,413 $ 45,741 $ 8,847,376

GOODWILL (Tables)

GOODWILL (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in Carrying Amount of Goodwill	(Dollars in thousands) September 30, December 31, Balance at beginning of year $ 204,084 $ 204,084 Goodwill resulting from business combinations 676,949 0 Balance at end of period $ 881,033 $ 204,084

BORROWINGS (Tables)

BORROWINGS (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Summary of Long-term Debt	The following is a summary of First Financial's long-term debt: September 30, 2018 December 31, 2017 (Dollars in thousands) Amount Average rate Amount Average rate Subordinated notes $ 177,887 5.13 % $ 120,000 5.13 % Unamortized discount and debt issuance costs (8,671 ) N/A (1,362 ) N/A FHLB borrowings 400,046 2.09 % 241 1.09 % Capital loan with municipality 775 0.00 % 775 0.00 % Total long-term debt $ 570,037 3.06 % $ 119,654 5.14 %

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Related Tax Effects Allocated to Other Comprehensive Income and Accumulated Other Comprehensive Income (Loss)	The related tax effects allocated to other comprehensive income and reclassifications out of accumulated other comprehensive income (loss) are as follows: Three months ended September 30, 2018 Total other comprehensive income (loss) Total accumulated other comprehensive income (loss) (Dollars in thousands) Prior to reclass Reclass from Pre-tax Tax effect Net of tax Beginning balance Net activity Ending balance Unrealized gain (loss) on debt securities $ (13,138 ) $ (167 ) $ (12,971 ) $ 2,786 $ (10,185 ) $ (19,179 ) $ (10,185 ) $ (29,364 ) Unrealized gain (loss) on derivatives 130 0 130 (31 ) 99 (386 ) 99 (287 ) Retirement obligation 0 (452 ) 452 (105 ) 347 (23,593 ) 347 (23,246 ) Total $ (13,008 ) $ (619 ) $ (12,389 ) $ 2,650 $ (9,739 ) $ (43,158 ) $ (9,739 ) $ (52,897 ) Three months ended September 30, 2017 Total other comprehensive income (loss) Total accumulated other comprehensive income (loss) (Dollars in thousands) Prior to reclass Reclass from Pre-tax Tax effect Net of tax Beginning balance Net activity Ending balance Unrealized gain (loss) on debt securities $ 2,612 $ 276 $ 2,336 $ (835 ) $ 1,501 $ 1,014 $ 1,501 $ 2,515 Unrealized gain (loss) on derivatives 202 0 202 (73 ) 129 (835 ) 129 (706 ) Retirement obligation 0 (335 ) 335 (122 ) 213 (22,401 ) 213 (22,188 ) Total $ 2,814 $ (59 ) $ 2,873 $ (1,030 ) $ 1,843 $ (22,222 ) $ 1,843 $ (20,379 ) Nine months ended September 30, 2018 Total other comprehensive income Total accumulated other comprehensive income (loss) (Dollars in thousands) Prior to Reclass Pre-tax Tax effect Net of tax Beginning balance Net activity Cumulative effect of accounting change Ending balance Unrealized gain (loss) on debt securities $ (37,130 ) $ (197 ) $ (36,933 ) $ 7,940 $ (28,993 ) $ (182 ) $ (28,993 ) $ (189 ) $ (29,364 ) Unrealized gain (loss) on derivatives 535 0 535 (121 ) 414 (577 ) 414 (124 ) (287 ) Retirement obligation 0 (1,323 ) 1,323 (159 ) 1,164 (19,631 ) 1,164 (4,779 ) (23,246 ) Total $ (36,595 ) $ (1,520 ) $ (35,075 ) $ 7,660 $ (27,415 ) $ (20,390 ) $ (27,415 ) $ (5,092 ) $ (52,897 ) Nine months ended September 30, 2017 Total other comprehensive income Total accumulated other comprehensive income (loss) (Dollars in thousands) Prior to Reclass Pre-tax Tax effect Net of tax Beginning balance Net activity Ending balance Unrealized gain (loss) on debt securities $ 12,614 $ 1,630 $ 10,984 $ (3,920 ) $ 7,064 $ (4,549 ) $ 7,064 $ 2,515 Unrealized gain (loss) on derivatives 607 0 607 (222 ) 385 (1,091 ) 385 (706 ) Retirement obligation 0 (1,005 ) 1,005 (390 ) 615 (22,803 ) 615 (22,188 ) Total $ 13,221 $ 625 $ 12,596 $ (4,532 ) $ 8,064 $ (28,443 ) $ 8,064 $ (20,379 )
Other Accumulated Comprehensive income reclassified from AOCI	The following table presents the activity reclassified from accumulated other comprehensive income into income during the three and nine month periods ended September 30, 2018 and 2017, respectively: Amount reclassified from accumulated other comprehensive income (1) Three months ended Nine months ended September 30, September 30, (Dollars in thousands) 2018 2017 2018 2017 Affected Line Item in the Consolidated Statements of Income Realized gain (loss) on securities available-for-sale $ (167 ) $ 276 $ (197 ) $ 1,630 Net gain (loss) on sales of investments securities Defined benefit pension plan Amortization of prior service cost (2) 104 103 310 310 Other noninterest expense (2018) Salaries and employee benefits (2017) Recognized net actuarial loss (2) (556 ) (438 ) (1,633 ) (1,315 ) Other noninterest expense (2018) Defined benefit pension plan total (452 ) (335 ) (1,323 ) (1,005 ) Total reclassifications for the period, before tax $ (619 ) $ (59 ) $ (1,520 ) $ 625 (1) Negative amounts are reductions to net income. (2)

DERIVATIVES (Tables)

DERIVATIVES (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Derivative Financial Instruments and Balances	The following table details the classification and amounts recognized in the Consolidated Balance Sheets for client derivatives: September 30, 2018 December 31, 2017 Estimated fair value Estimated fair value (Dollars in thousands) Balance sheet classification Notional amount Gain Loss Notional amount Gain Loss Client derivatives - instruments associated with loans Matched interest rate swaps with borrower Accrued interest and other assets $ 1,312,293 $ 4,046 $ (29,240 ) $ 837,040 $ 7,153 $ (5,529 ) Matched interest rate swaps with counterparty Accrued interest and other liabilities 1,312,293 29,240 (4,038 ) 837,040 5,529 (7,158 ) Total $ 2,624,586 $ 33,286 $ (33,278 ) $ 1,674,080 $ 12,682 $ (12,687 )
Disclosure by Type of Financial Instrument	The following table discloses the gross and net amounts of client derivative liabilities recognized in the Consolidated Balance Sheets: September 30, 2018 December 31, 2017 (Dollars in thousands) Gross amounts of recognized liabilities Gross amounts offset in the Consolidated Balance Sheets Net amounts of liabilities presented in the Consolidated Balance Sheets Gross amounts of recognized liabilities Gross amounts offset in the Consolidated Balance Sheets Net amounts of liabilities presented in the Consolidated Balance Sheets Client derivatives Matched interest rate swaps with counterparty $ 33,286 $ (4,900 ) $ 28,386 $ 12,687 $ 2,279 $ 14,966
Derivative Financial Instruments, Average Remaining Maturity and the Weighted-Average Interest Rates being Paid and Received	The following table details the derivative financial instruments, the average remaining maturities and the weighted-average interest rates being paid and received by First Financial at September 30, 2018 : Weighted-average rate (Dollars in thousands) Notional amount Average maturity (years) Fair value Receive Pay Client derivatives Receive fixed, matched interest rate swaps with borrower $ 1,312,293 4.6 $ (25,194 ) 4.62 % 4.23 % Pay fixed, matched interest rate swaps with counterparty 1,312,293 4.6 25,202 4.23 % 4.62 % Total client derivatives $ 2,624,586 4.6 $ 8 4.42 % 4.42 %

EMPLOYEE BENEFIT PLANS (Tables)

EMPLOYEE BENEFIT PLANS (Tables)	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Employee Benefit Plan Amounts Recognized in the Consolidated Balance Sheets and Consolidated Statements of Income	The following table sets forth information concerning amounts recognized in First Financial’s Consolidated Statements of Income related to the Company's pension plan: Three months ended Nine months ended September 30, September 30, (Dollars in thousands) 2018 2017 2018 2017 Service cost $ 1,736 $ 1,238 $ 4,766 $ 3,715 Interest cost 601 589 1,792 1,767 Expected return on assets (2,450 ) (2,481 ) (7,360 ) (7,443 ) Amortization of prior service cost (104 ) (103 ) (310 ) (310 ) Net actuarial loss 556 438 1,633 1,315 Net periodic benefit cost (income) $ 339 $ (319 ) $ 521 $ (956 )

EARNINGS PER COMMON SHARE (Tabl

EARNINGS PER COMMON SHARE (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Share	The following table sets forth the computation of basic and diluted earnings per share: Three months ended Nine months ended September 30, September 30, (Dollars in thousands, except per share data) 2018 2017 2018 2017 Numerator Net income available to common shareholders $ 50,657 $ 24,826 $ 117,581 $ 71,976 Denominator Basic earnings per common share - weighted average shares 97,411,201 61,577,619 85,602,116 61,507,160 Effect of dilutive securities Employee stock awards 536,760 552,774 515,566 617,128 Warrants 536,267 59,244 522,245 61,586 Diluted earnings per common share - adjusted weighted average shares 98,484,228 62,189,637 86,639,927 62,185,874 Earnings per share available to common shareholders Basic $ 0.52 $ 0.40 $ 1.37 $ 1.17 Diluted $ 0.51 $ 0.40 $ 1.36 $ 1.16

FAIR VALUE DISCLOSURES (Tables)

FAIR VALUE DISCLOSURES (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Estimated Fair Values of Financial Instruments	The estimated fair values of First Financial’s financial instruments not measured at fair value on a recurring or nonrecurring basis in the consolidated financial statements were as follows: Carrying Estimated fair value (Dollars in thousands) value Total Level 1 Level 2 Level 3 September 30, 2018 Financial assets Cash and short-term investments $ 222,277 $ 222,277 $ 222,277 $ 0 $ 0 Investment securities held-to-maturity 434,369 422,638 0 422,638 0 Other investments 115,757 N/A N/A N/A N/A Loans held for sale 13,277 13,277 0 13,277 0 Loans and leases 8,789,661 8,737,769 0 0 8,737,769 Accrued interest receivable 41,755 41,755 0 13,674 28,081 Financial liabilities Deposits 9,752,634 9,722,689 0 9,722,689 0 Short-term borrowings 1,294,252 1,294,252 1,294,252 0 0 Long-term debt 570,037 547,569 0 547,569 0 Accrued interest payable 10,517 10,517 2,963 7,554 0 Carrying Estimated fair value (Dollars in thousands) value Total Level 1 Level 2 Level 3 December 31, 2017 Financial assets Cash and short-term investments $ 184,624 $ 184,624 $ 184,624 $ 0 $ 0 Investment securities held-to-maturity 654,008 653,101 0 653,101 0 Other investments 53,140 N/A N/A N/A N/A Loans held for sale 11,502 11,502 0 11,502 0 Loans and leases 5,959,162 6,006,656 0 0 6,006,656 Accrued interest receivable 24,496 24,496 0 8,265 16,231 Financial liabilities Deposits 6,895,046 6,884,615 0 6,884,615 0 Short-term borrowings 814,565 814,565 814,565 0 0 Long-term debt 119,654 117,908 0 117,908 0 Accrued interest payable 5,104 5,104 204 4,900 0
Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	The financial assets and liabilities measured at fair value on a recurring basis in the consolidated financial statements were as follows: Fair value measurements using (Dollars in thousands) Level 1 Level 2 Level 3 Assets/liabilities at fair value September 30, 2018 Assets Derivatives $ 0 $ 33,806 $ 0 $ 33,806 Investment securities available-for-sale 95 2,626,631 0 2,626,726 Total $ 95 $ 2,660,437 $ 0 $ 2,660,532 Liabilities Derivatives $ 0 $ 33,321 $ 0 $ 33,321 Fair value measurements using (Dollars in thousands) Level 1 Level 2 Level 3 Assets/liabilities at fair value December 31, 2017 Assets Derivatives $ 0 $ 12,757 $ 0 $ 12,757 Investment securities available-for-sale 2,969 1,346,439 0 1,349,408 Total $ 2,969 $ 1,359,196 $ 0 $ 1,362,165 Liabilities Derivatives $ 0 $ 12,755 $ 0 $ 12,755
Summary of Financial Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis	The following table summarizes financial assets and liabilities measured at fair value on a nonrecurring basis. Fair value measurements using (Dollars in thousands) Level 1 Level 2 Level 3 September 30, 2018 Assets Impaired loans $ 0 $ 0 $ 2,816 OREO 0 0 1,515 Fair value measurements using (Dollars in thousands) Level 1 Level 2 Level 3 December 31, 2017 Assets Impaired loans $ 0 $ 0 $ 2,671 OREO 0 0 1,086

BUSINESS COMBINATIONS (Tables)

BUSINESS COMBINATIONS (Tables)	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table provides the purchase price calculation as of the acquisition date, identifiable assets purchased and liabilities assumed at their estimated fair value. As a condition of the merger, certain acquired assets and liabilities held for sale were divested subsequent to the closing of the merger. There was no gain or loss recorded in the Consolidated Statement of Income in conjunction with this divestiture. (Dollars in thousands) MainSource Purchase consideration Cash consideration $ 43 Stock consideration 1,045,876 Warrant consideration 14,460 Options consideration 1,577 Total purchase consideration 1,061,956 Assets acquired Cash 71,734 Investment securities available-for-sale 901,008 Investment securities held-to-maturity 171,423 Other investments 28,763 Loans 2,792,517 Premises and equipment 98,537 Intangible assets 42,887 Other assets 169,311 Assets held for sale 127,775 Total assets acquired 4,403,955 Liabilities assumed Deposits 3,264,038 Subordinated notes 49,027 FHLB advances 291,887 Other borrowings 205,620 Other liabilities 32,654 Liabilities held for sale 175,722 Total liabilities assumed 4,018,948 Net identifiable assets 385,007 Goodwill $ 676,949
Business Acquisition, Pro Forma Information, Nonrecurring Adjustments	Nine months ended September 30, (Dollars in thousands, except per share data) 2018 2017 Pro Forma Condensed Combined Income Statement Information Net interest income $ 362,112 $ 334,736 Net income 161,323 93,293 Basic earnings per share 1.66 0.96 Diluted earnings per share 1.64 0.95

RECENTLY ADOPTED AND ISSUED A_2

RECENTLY ADOPTED AND ISSUED ACCOUNTING STANDARDS RECENTLY ADOPTED AND ISSUED ACCOUNTING STANDARDS - Additional Information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
OtherComprehensiveIncomeLossReclassificationAdjustmentFromAociForSaleOfSecuritiesDisproportionateTaxEffect	$ (189)
Retained earnings
Reclassification from AOCI, Current Period, Tax	$ 4,900

INVESTMENTS INVESTMENTS - Addit

INVESTMENTS INVESTMENTS - Additional Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017
Gain (Loss) on Securities [Line Items]
NumberOfSecuritiesInSecurityPortfolio	1,414		1,414		775
NumberOfSecuritiesInUnrealizedLossPosition	909		909		237
Proceeds from Sale of Debt Securities, Available-for-sale	$ 43,322	$ 53,900	$ 259,500	$ 179,600
Available-for-sale Securities, Gross Realized Gains	267	400	270	1,800
Available-for-sale Securities, Gross Realized Losses	$ 434	$ 100	467	$ 200
Debt Securities, Held-to-maturity, Transfer, Amount			$ 367,900

INVESTMENTS - Summary of Held-T

INVESTMENTS - Summary of Held-To-Maturity and Available-For-Sale Investment Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Total	$ 434,369	$ 654,008
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	275	5,572
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(12,006)	(6,479)
Held-to-Maturity Market Value	422,638	653,101
Total	2,662,329	1,348,227
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	4,770	8,328
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(40,373)	(7,147)
Investment securities available-for-sale	2,626,726	1,349,408
U.S. Treasuries
Investment Holdings [Line Items]
Total	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Held-to-Maturity Market Value	0	0
Total	99	98
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	0	0
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(4)	(1)
Investment securities available-for-sale	95	97
Securities of U.S. government agencies and corporations
Investment Holdings [Line Items]
Total	0	11,168
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	(76)
Held-to-Maturity Market Value	0	11,092
Total	33,438	15,695
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	7	220
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(600)	0
Investment securities available-for-sale	32,845	15,915
Residential Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Total	26,603	162,093
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	2,042
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(1,615)	(1,535)
Held-to-Maturity Market Value	24,988	162,600
Total	581,657	290,793
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	551	849
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(14,262)	(2,599)
Investment securities available-for-sale	567,946	289,043
Commercial Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Total	150,223	255,027
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	1,372
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(6,378)	(3,000)
Held-to-Maturity Market Value	143,845	253,399
Total	362,874	150,356
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	118	164
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(5,646)	(1,417)
Investment securities available-for-sale	357,346	149,103
Collateralized Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Total	13,182	143,545
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	354
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(727)	(1,602)
Held-to-Maturity Market Value	12,455	142,297
Total	864,824	306,095
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	940	1,158
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(15,436)	(1,861)
Investment securities available-for-sale	850,328	305,392
Obligations of state and other political subdivisions
Investment Holdings [Line Items]
Total	244,361	82,175
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	275	1,804
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(3,286)	(266)
Held-to-Maturity Market Value	241,350	83,713
Total	247,206	124,269
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	1,533	2,162
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(2,626)	(676)
Investment securities available-for-sale	246,113	125,755
Asset-backed Securities [Member]
Investment Holdings [Line Items]
Total	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Held-to-Maturity Market Value	0	0
Total	490,685	377,655
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	582	1,628
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(1,499)	(306)
Investment securities available-for-sale	489,768	378,977
Other securities
Investment Holdings [Line Items]
Total	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Held-to-Maturity Market Value	0	0
Total	81,546	83,266
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	1,039	2,147
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(300)	(287)
Investment securities available-for-sale	$ 82,285	$ 85,126

INVESTMENTS - Summary of Invest

INVESTMENTS - Summary of Investment Securities by Estimated Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Held-to-Maturity Amortized Cost
Amortized Cost	$ 434,369	$ 654,008
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	422,638	653,101
Available-for-Sale Amortized Cost
Available-for-sale Securities, Amortized Cost Basis	2,662,329	1,348,227
Available-for-Sale Market Value
Investment securities available-for-sale	2,626,726	1,349,408
One Year or Less [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	0
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	0
Available-for-Sale Amortized Cost
Available-for-sale Securities, Amortized Cost Basis	3,932
Available-for-Sale Market Value
Investment securities available-for-sale	3,922
After One Year Through Five Years [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	275
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	277
Available-for-Sale Amortized Cost
Available-for-sale Securities, Amortized Cost Basis	72,831
Available-for-Sale Market Value
Investment securities available-for-sale	72,633
After Five Years Through Ten Years [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	18,337
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	18,274
Available-for-Sale Amortized Cost
Available-for-sale Securities, Amortized Cost Basis	138,584
Available-for-Sale Market Value
Investment securities available-for-sale	139,591
After Ten Years [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	225,749
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	222,799
Available-for-Sale Amortized Cost
Available-for-sale Securities, Amortized Cost Basis	146,942
Available-for-Sale Market Value
Investment securities available-for-sale	145,192
Residential Mortgage Backed Securities [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	26,603	162,093
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	24,988	162,600
Available-for-Sale Amortized Cost
Available-for-sale Securities, Amortized Cost Basis	581,657	290,793
Available-for-Sale Market Value
Investment securities available-for-sale	567,946	289,043
Commercial Mortgage Backed Securities [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	150,223	255,027
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	143,845	253,399
Available-for-Sale Amortized Cost
Available-for-sale Securities, Amortized Cost Basis	362,874	150,356
Available-for-Sale Market Value
Investment securities available-for-sale	357,346	149,103
Collateralized Mortgage Backed Securities [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	13,182	143,545
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	12,455	142,297
Available-for-Sale Amortized Cost
Available-for-sale Securities, Amortized Cost Basis	864,824	306,095
Available-for-Sale Market Value
Investment securities available-for-sale	850,328	305,392
Asset-backed Securities [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	0	0
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	0	0
Available-for-Sale Amortized Cost
Available-for-sale Securities, Amortized Cost Basis	490,685	377,655
Available-for-Sale Market Value
Investment securities available-for-sale	$ 489,768	$ 378,977

INVESTMENTS - Age of Gross Unre

INVESTMENTS - Age of Gross Unrealized Losses and Associated Fair Value by Investment Category (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	$ 1,920,376	$ 570,095
Less than 12 Months Unrealized Loss	(28,443)	(4,745)
12 Months or More Fair Value	494,421	335,516
12 Months or More Unrealized Loss	(23,936)	(8,881)
Total Fair Value	2,414,797	905,611
Total Unrealized Loss	(52,379)	(13,626)
U.S. Treasuries
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	0	97
Less than 12 Months Unrealized Loss	0	(1)
12 Months or More Fair Value	95	0
12 Months or More Unrealized Loss	(4)	0
Total Fair Value	95	97
Total Unrealized Loss	(4)	(1)
Securities of U.S. government agencies and corporations
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	19,546	11,092
Less than 12 Months Unrealized Loss	(411)	(76)
12 Months or More Fair Value	5,332	0
12 Months or More Unrealized Loss	(189)	0
Total Fair Value	24,878	11,092
Total Unrealized Loss	(600)	(76)
Residential Mortgage Backed Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	431,332	175,183
Less than 12 Months Unrealized Loss	(8,695)	(1,109)
12 Months or More Fair Value	141,519	108,782
12 Months or More Unrealized Loss	(7,182)	(3,025)
Total Fair Value	572,851	283,965
Total Unrealized Loss	(15,877)	(4,134)
Commercial Mortgage Backed Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	281,842	132,818
Less than 12 Months Unrealized Loss	(3,637)	(1,713)
12 Months or More Fair Value	151,185	72,139
12 Months or More Unrealized Loss	(8,387)	(2,704)
Total Fair Value	433,027	204,957
Total Unrealized Loss	(12,024)	(4,417)
Collateralized Mortgage Backed Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	658,749	164,909
Less than 12 Months Unrealized Loss	(10,407)	(1,138)
12 Months or More Fair Value	133,153	101,436
12 Months or More Unrealized Loss	(5,756)	(2,325)
Total Fair Value	791,902	266,345
Total Unrealized Loss	(16,163)	(3,463)
Obligations of state and other political subdivisions
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	304,298	38,450
Less than 12 Months Unrealized Loss	(3,976)	(507)
12 Months or More Fair Value	37,683	21,639
12 Months or More Unrealized Loss	(1,936)	(435)
Total Fair Value	341,981	60,089
Total Unrealized Loss	(5,912)	(942)
Asset-backed Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	206,708	44,941
Less than 12 Months Unrealized Loss	(1,125)	(200)
12 Months or More Fair Value	20,776	24,396
12 Months or More Unrealized Loss	(374)	(106)
Total Fair Value	227,484	69,337
Total Unrealized Loss	(1,499)	(306)
Other securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	17,901	2,605
Less than 12 Months Unrealized Loss	(192)	(1)
12 Months or More Fair Value	4,678	7,124
12 Months or More Unrealized Loss	(108)	(286)
Total Fair Value	22,579	9,729
Total Unrealized Loss	$ (300)	$ (287)

LOANS AND LEASES - Additional I

LOANS AND LEASES - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured Loans, Portion Determined to be Uncollectible	$ 700,000	$ 100,000		$ 200,000
Purchased impaired loans	105,022,000		$ 105,022,000			$ 104,960,000
Restructured Loans, Nonaccrual Status	4,700,000		4,700,000			6,400,000
Write-downs	455,000	134,000	717,000	415,000
Gain (loss) on sale of other real estate owned	(538,000)	(237,000)	(332,000)	(423,000)
Real Estate Acquired Through Foreclosure	1,918,000	3,116,000	1,918,000	3,116,000	$ 1,853,000	$ 2,781,000	$ 5,961,000	$ 6,284,000
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured Loans, Loan Relationships, Review Threshold Amount Minimum			250,000
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured Loans, Loan Relationships, Review Threshold Amount Minimum			250,000
Write-downs	197,000	$ 32,000	362,000	$ 151,000
MainSource [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased impaired loans	$ 18,000,000		$ 18,000,000

LOANS AND LEASES - Commercial a

LOANS AND LEASES - Commercial and Consumer Credit Exposure by Risk Attribute (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Commercial	$ 2,426,590	$ 1,912,743
Real Estate - Construction	565,077	467,730
Real Estate - Commercial	3,868,143	2,490,091
Lease financing	95,317	89,347
Total Commercial	6,955,127	4,959,911
Pass
Financing Receivable, Recorded Investment [Line Items]
Commercial	2,335,925	1,882,464
Real Estate - Construction	552,973	467,687
Real Estate - Commercial	3,757,627	2,446,999
Lease financing	92,551	88,078
Total Commercial	6,739,076	4,885,228
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Commercial	39,060	6,226
Real Estate - Construction	12,094	0
Real Estate - Commercial	49,463	4,436
Lease financing	0	0
Total Commercial	100,617	10,662
Substandard
Financing Receivable, Recorded Investment [Line Items]
Commercial	51,605	24,053
Real Estate - Construction	10	43
Real Estate - Commercial	61,053	38,656
Lease financing	2,766	1,269
Total Commercial	115,434	64,021
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Commercial	0	0
Real Estate - Construction	0	0
Real Estate - Commercial	0	0
Lease financing	0	0
Total Commercial	0	0
Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	932,962	471,391
Residential real estate | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	919,440	463,459
Residential real estate | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	13,522	7,932
Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	816,133	493,604
Home equity | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	809,653	489,148
Home equity | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	6,480	4,456
Installment
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	97,413	41,586
Installment | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	97,097	41,331
Installment | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	316	255
Credit card
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	45,741	46,691
Credit card | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	45,741	46,691
Credit card | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	0	0
Total consumer loans
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	1,892,249	1,053,272
Total consumer loans | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	1,871,931	1,040,629
Total consumer loans | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	$ 20,318	$ 12,643

LOANS AND LEASES - Loan Delinqu

LOANS AND LEASES - Loan Delinquency, including Nonaccrual Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 44,266	$ 27,942
Current	8,698,088	5,880,281
Loans and Leases Receivable, Gross	8,742,354	5,908,223
Purchased impaired loans	105,022	104,960
Total loans and leases	8,847,376	6,013,183
> 90 days past due and still accruing	144	62
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	13,520	6,896
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	5,384	3,179
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	25,362	17,867
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	6,266	7,490
Current	2,414,484	1,901,821
Loans and Leases Receivable, Gross	2,420,750	1,909,311
Purchased impaired loans	5,840	3,432
Total loans and leases	2,426,590	1,912,743
> 90 days past due and still accruing	0	0
Commercial | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,991	755
Commercial | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,613	1,657
Commercial | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	2,662	5,078
Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	485
Current	95,317	88,862
Loans and Leases Receivable, Gross	95,317	89,347
Purchased impaired loans	0	0
Total loans and leases	95,317	89,347
> 90 days past due and still accruing	0	0
Lease financing | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	485
Lease financing | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Lease financing | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Construction real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	283	234
Current	564,535	467,216
Loans and Leases Receivable, Gross	564,818	467,450
Purchased impaired loans	259	280
Total loans and leases	565,077	467,730
> 90 days past due and still accruing	0	0
Construction real estate | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	283	234
Construction real estate | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Construction real estate | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	21,216	10,694
Current	3,789,238	2,419,969
Loans and Leases Receivable, Gross	3,810,454	2,430,663
Purchased impaired loans	57,689	59,428
Total loans and leases	3,868,143	2,490,091
> 90 days past due and still accruing	0	0
Commercial real estate | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	4,513	1,716
Commercial real estate | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	407	201
Commercial real estate | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	16,296	8,777
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	7,449	3,329
Current	888,367	430,500
Loans and Leases Receivable, Gross	895,816	433,829
Purchased impaired loans	37,146	37,562
Total loans and leases	932,962	471,391
> 90 days past due and still accruing	0	0
Residential real estate | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	2,796	526
Residential real estate | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,828	811
Residential real estate | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	2,825	1,992
Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	7,924	4,863
Current	804,670	485,127
Loans and Leases Receivable, Gross	812,594	489,990
Purchased impaired loans	3,539	3,614
Total loans and leases	816,133	493,604
> 90 days past due and still accruing	0	0
Home equity | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	3,435	2,716
Home equity | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,336	394
Home equity | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	3,153	1,753
Installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	504	413
Current	96,360	40,529
Loans and Leases Receivable, Gross	96,864	40,942
Purchased impaired loans	549	644
Total loans and leases	97,413	41,586
> 90 days past due and still accruing	0	0
Installment | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	201	179
Installment | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	21	29
Installment | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	282	205
Credit card
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	624	434
Current	45,117	46,257
Loans and Leases Receivable, Gross	45,741	46,691
Purchased impaired loans	0	0
Total loans and leases	45,741	46,691
> 90 days past due and still accruing	144	62
Credit card | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	301	285
Credit card | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	179	87
Credit card | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 144	$ 62

LOANS AND LEASES - Restructured

LOANS AND LEASES - Restructured Loans (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)loans	Sep. 30, 2017USD ($)loans	Sep. 30, 2018USD ($)loansd	Sep. 30, 2017USD ($)loans	Dec. 31, 2017USD ($)loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extended Maturities	$ 143,000	$ 0	$ 3,031,000	$ 3,261,000
Adjusted Interest Rates	0	0	52,000	2,767,000
Combined Rate And Maturity	0	285,000	0	465,000
Forebearance Agreements	0	354,000	6,199,000	1,181,000
Other	10,000	37,000	349,000	75,000
Total	$ 153,000	$ 676,000	$ 9,631,000	$ 7,749,000
Restructured loans, Number of Loans | loans	2	9	23	21
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 158,000	$ 785,000	$ 9,720,000	$ 7,970,000
Restructured loans, Period End Balance	$ 153,000	$ 676,000	$ 9,631,000	$ 7,749,000
Restructured loans with payment default within 12 months of modification, Number of Loans | loans	0	0	1	0
Restructured loans with payment default within 12 months of modification, Period End Balance	$ 0	$ 0	$ 41,000	$ 0
Number of Restructured Loans | loans	187		187		214
Total restructured loans	$ 25,000,000		$ 25,000,000		$ 23,900,000
Restructured loans on accrual status	20,313,000		20,313,000		17,545,000
Restructured Loans, Nonaccrual Status	4,700,000		4,700,000		6,400,000
Allowance for loan and lease losses lncluded in reserves for restructured loans	2,300,000		2,300,000		1,300,000
Restructured Loans, Portion Determined to be Uncollectible	700,000	$ 100,000		$ 200,000
Accruing TDRs performing in accordance with restructured terms for more than one year	$ 12,600,000		$ 12,600,000		$ 17,200,000
Restructured loans performance threshold (days) | d			90
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans | loans	0	1	12	7
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 0	$ 45,000	$ 7,149,000	$ 5,724,000
Restructured loans, Period End Balance	$ 0	$ 37,000	$ 7,096,000	$ 5,661,000
Construction real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans | loans	0	0	0	0
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 0	$ 0	$ 0	$ 0
Restructured loans, Period End Balance	$ 0	$ 0	$ 0	$ 0
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans | loans	0	1	6	7
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 0	$ 285,000	$ 2,119,000	$ 1,791,000
Restructured loans, Period End Balance	$ 0	$ 285,000	$ 2,088,000	$ 1,734,000
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans | loans	1	6	4	6
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 148,000	$ 416,000	$ 442,000	$ 416,000
Restructured loans, Period End Balance	$ 143,000	$ 315,000	437,000	$ 315,000
Restructured Loans, Loan Relationships, Review Threshold Amount Minimum			$ 250,000
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans | loans	1	1	1	1
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 10,000	$ 39,000	$ 10,000	$ 39,000
Restructured loans, Period End Balance	$ 10,000	$ 39,000	$ 10,000	$ 39,000
Installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans | loans	0	0	0	0
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 0	$ 0	$ 0	$ 0
Restructured loans, Period End Balance	$ 0	$ 0	$ 0	$ 0

LOANS AND LEASES - Nonaccrual,

LOANS AND LEASES - Nonaccrual, Restructured and Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Average current balance	$ 62,493	$ 53,260	$ 52,960	$ 54,402
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	39	15	67	67
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	317	293	828	941
Nonaccrual loans	42,368		42,368		$ 24,082
Accruing trouble debt restructurings	20,313		20,313		17,545
Total impaired loans	62,681		62,681		41,627
Restructured loans - nonaccrual status	4,700		4,700		6,400
Interest income effect
Gross amount of interest that would have been recorded under original terms	1,192	761	3,126	2,735
Interest included in income
Nonaccrual loans	169	140	395	445
Troubled debt restructurings	187	168	500	563
Total interest included in income	356	308	895	1,008
Net impact on interest income	836	453	2,231	1,727
Commercial
Financing Receivable, Modifications [Line Items]
Average current balance	11,611	15,562	9,841	16,132
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	28	2	34	26
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	63	63	162	259
Nonaccrual loans	4,310		4,310		5,229
Total impaired loans	11,985		11,985		7,331
Interest included in income
Total interest included in income	91	65	196	285
Lease financing
Financing Receivable, Modifications [Line Items]
Average current balance	0	91	21	120
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	0	0	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	0	1	0	3
Nonaccrual loans	0		0		82
Total impaired loans	0		0		82
Interest included in income
Total interest included in income	0	1	0	3
Construction real estate
Financing Receivable, Modifications [Line Items]
Average current balance	17	950	22	744
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	0	0	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	0	0	2	0
Nonaccrual loans	10		10		29
Total impaired loans	10		10		29
Interest included in income
Total interest included in income	0	0	2	0
Commercial real estate
Financing Receivable, Modifications [Line Items]
Average current balance	29,701	23,839	26,420	24,076
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	3	5	9	18
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	136	147	375	451
Nonaccrual loans	20,338		20,338		10,616
Total impaired loans	28,390		28,390		21,542
Interest included in income
Total interest included in income	139	152	384	469
Residential real estate
Financing Receivable, Modifications [Line Items]
Average current balance	14,283	8,636	10,918	8,927
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	7	7	21	20
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	86	55	209	147
Nonaccrual loans	11,365		11,365		4,140
Total impaired loans	15,310		15,310		7,932
Interest included in income
Total interest included in income	93	62	230	167
Home equity
Financing Receivable, Modifications [Line Items]
Average current balance	6,563	3,892	5,439	4,052
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	1	1	3	3
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	31	26	78	77
Nonaccrual loans	6,018		6,018		3,743
Total impaired loans	6,654		6,654		4,456
Interest included in income
Total interest included in income	32	27	81	80
Installment
Financing Receivable, Modifications [Line Items]
Average current balance	318	290	299	351
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	0	0	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	1	1	2	4
Nonaccrual loans	327		327		243
Total impaired loans	332		332		255
Interest included in income
Total interest included in income	1	1	2	4
Loans with no related allowance recorded [member]
Financing Receivable, Modifications [Line Items]
Average current balance	58,767	49,608	49,550	49,199
Total impaired loans	57,104		57,104		37,183
Loans with no related allowance recorded [member] | Commercial
Financing Receivable, Modifications [Line Items]
Average current balance	10,033	13,730	8,950	14,669
Total impaired loans	9,209		9,209		7,162
Loans with no related allowance recorded [member] | Lease financing
Financing Receivable, Modifications [Line Items]
Average current balance	0	91	21	120
Total impaired loans	0		0		82
Loans with no related allowance recorded [member] | Construction real estate
Financing Receivable, Modifications [Line Items]
Average current balance	17	950	22	744
Total impaired loans	10		10		29
Loans with no related allowance recorded [member] | Commercial real estate
Financing Receivable, Modifications [Line Items]
Average current balance	28,689	23,187	25,044	21,563
Total impaired loans	26,722		26,722		18,423
Loans with no related allowance recorded [member] | Residential real estate
Financing Receivable, Modifications [Line Items]
Average current balance	13,247	7,569	9,875	7,801
Total impaired loans	14,277		14,277		6,876
Loans with no related allowance recorded [member] | Home equity
Financing Receivable, Modifications [Line Items]
Average current balance	6,463	3,791	5,339	3,951
Total impaired loans	6,554		6,554		4,356
Loans with no related allowance recorded [member] | Installment
Financing Receivable, Modifications [Line Items]
Average current balance	318	290	299	351
Total impaired loans	332		332		255
Impaired Financing Receivables With Related Allowance [Member]
Financing Receivable, Modifications [Line Items]
Total impaired loans	5,577		5,577
Impaired Financing Receivables With Related Allowance [Member] | Commercial
Financing Receivable, Modifications [Line Items]
Average current balance	1,578	1,832	891	1,463
Total impaired loans	2,776		2,776		169
Impaired Financing Receivables With Related Allowance [Member] | Lease financing
Financing Receivable, Modifications [Line Items]
Average current balance	0	0	0	0
Total impaired loans	0		0		0
Impaired Financing Receivables With Related Allowance [Member] | Construction real estate
Financing Receivable, Modifications [Line Items]
Average current balance	0	0	0	0
Total impaired loans	0		0		0
Impaired Financing Receivables With Related Allowance [Member] | Commercial real estate
Financing Receivable, Modifications [Line Items]
Average current balance	1,012	652	1,376	2,513
Total impaired loans	1,668		1,668		3,119
Impaired Financing Receivables With Related Allowance [Member] | Residential real estate
Financing Receivable, Modifications [Line Items]
Average current balance	1,036	1,067	1,043	1,126
Total impaired loans	1,033		1,033		1,056
Impaired Financing Receivables With Related Allowance [Member] | Home equity
Financing Receivable, Modifications [Line Items]
Average current balance	100	101	100	101
Total impaired loans	100		100		100
Impaired Financing Receivables With Related Allowance [Member] | Installment
Financing Receivable, Modifications [Line Items]
Average current balance	0	0	0	0
Total impaired loans	0		0		0
Impaired Financing Receivables With Related Allowance [Member]
Financing Receivable, Modifications [Line Items]
Average current balance	$ 3,726	$ 3,652	$ 3,410	$ 5,203
Total impaired loans					$ 4,444

LOANS AND LEASES - Investment i

LOANS AND LEASES - Investment in Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 42,368		$ 42,368		$ 24,082
Current balance	62,681		62,681		41,627
Contractual Principal Balance	77,057		77,057		47,857
Related Allowance	1,790		1,790		779
Average current balance	62,493	$ 53,260	52,960	$ 54,402
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	39	15	67	67
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	317	293	828	941
Interest income recognized	356	308	895	1,008
Commercial
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	4,310		4,310		5,229
Current balance	11,985		11,985		7,331
Contractual Principal Balance	15,810		15,810		8,629
Related Allowance	1,562		1,562		169
Average current balance	11,611	15,562	9,841	16,132
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	28	2	34	26
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	63	63	162	259
Interest income recognized	91	65	196	285
Lease financing
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	0		0		82
Current balance	0		0		82
Contractual Principal Balance	0		0		82
Related Allowance	0		0		0
Average current balance	0	91	21	120
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	0	0	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	0	1	0	3
Interest income recognized	0	1	0	3
Construction real estate
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	10		10		29
Current balance	10		10		29
Contractual Principal Balance	27		27		60
Related Allowance	0		0		0
Average current balance	17	950	22	744
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	0	0	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	0	0	2	0
Interest income recognized	0	0	2	0
Commercial real estate
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	20,338		20,338		10,616
Current balance	28,390		28,390		21,542
Contractual Principal Balance	35,028		35,028		23,957
Related Allowance	66		66		448
Average current balance	29,701	23,839	26,420	24,076
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	3	5	9	18
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	136	147	375	451
Interest income recognized	139	152	384	469
Residential real estate
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	11,365		11,365		4,140
Current balance	15,310		15,310		7,932
Contractual Principal Balance	18,116		18,116		9,208
Related Allowance	160		160		160
Average current balance	14,283	8,636	10,918	8,927
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	7	7	21	20
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	86	55	209	147
Interest income recognized	93	62	230	167
Home equity
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	6,018		6,018		3,743
Current balance	6,654		6,654		4,456
Contractual Principal Balance	7,437		7,437		5,499
Related Allowance	2		2		2
Average current balance	6,563	3,892	5,439	4,052
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	1	1	3	3
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	31	26	78	77
Interest income recognized	32	27	81	80
Installment
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	327		327		243
Current balance	332		332		255
Contractual Principal Balance	639		639		422
Related Allowance	0		0		0
Average current balance	318	290	299	351
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	0	0	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	1	1	2	4
Interest income recognized	1	1	2	4
Loans with no related allowance recorded [member]
Financing Receivable, Impaired [Line Items]
Current balance	57,104		57,104		37,183
Contractual Principal Balance	70,826		70,826		43,405
Related Allowance	0		0		0
Average current balance	58,767	49,608	49,550	49,199
Loans with no related allowance recorded [member] | Commercial
Financing Receivable, Impaired [Line Items]
Current balance	9,209		9,209		7,162
Contractual Principal Balance	13,034		13,034		8,460
Related Allowance	0		0		0
Average current balance	10,033	13,730	8,950	14,669
Loans with no related allowance recorded [member] | Lease financing
Financing Receivable, Impaired [Line Items]
Current balance	0		0		82
Contractual Principal Balance	0		0		82
Related Allowance	0		0		0
Average current balance	0	91	21	120
Loans with no related allowance recorded [member] | Construction real estate
Financing Receivable, Impaired [Line Items]
Current balance	10		10		29
Contractual Principal Balance	27		27		60
Related Allowance	0		0		0
Average current balance	17	950	22	744
Loans with no related allowance recorded [member] | Commercial real estate
Financing Receivable, Impaired [Line Items]
Current balance	26,722		26,722		18,423
Contractual Principal Balance	32,706		32,706		20,837
Related Allowance	0		0		0
Average current balance	28,689	23,187	25,044	21,563
Loans with no related allowance recorded [member] | Residential real estate
Financing Receivable, Impaired [Line Items]
Current balance	14,277		14,277		6,876
Contractual Principal Balance	17,083		17,083		8,145
Related Allowance	0		0		0
Average current balance	13,247	7,569	9,875	7,801
Loans with no related allowance recorded [member] | Home equity
Financing Receivable, Impaired [Line Items]
Current balance	6,554		6,554		4,356
Contractual Principal Balance	7,337		7,337		5,399
Related Allowance	0		0		0
Average current balance	6,463	3,791	5,339	3,951
Loans with no related allowance recorded [member] | Installment
Financing Receivable, Impaired [Line Items]
Current balance	332		332		255
Contractual Principal Balance	639		639		422
Related Allowance	0		0		0
Average current balance	318	290	299	351
Impaired Financing Receivables With Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Current balance	5,577		5,577
Contractual Principal Balance	6,231		6,231
Related Allowance	1,790		1,790
Impaired Financing Receivables With Related Allowance [Member] | Commercial
Financing Receivable, Impaired [Line Items]
Current balance	2,776		2,776		169
Contractual Principal Balance	2,776		2,776		169
Related Allowance	1,562		1,562		169
Average current balance	1,578	1,832	891	1,463
Impaired Financing Receivables With Related Allowance [Member] | Lease financing
Financing Receivable, Impaired [Line Items]
Current balance	0		0		0
Contractual Principal Balance	0		0		0
Related Allowance	0		0		0
Average current balance	0	0	0	0
Impaired Financing Receivables With Related Allowance [Member] | Construction real estate
Financing Receivable, Impaired [Line Items]
Current balance	0		0		0
Contractual Principal Balance	0		0		0
Related Allowance	0		0		0
Average current balance	0	0	0	0
Impaired Financing Receivables With Related Allowance [Member] | Commercial real estate
Financing Receivable, Impaired [Line Items]
Current balance	1,668		1,668		3,119
Contractual Principal Balance	2,322		2,322		3,120
Related Allowance	66		66		448
Average current balance	1,012	652	1,376	2,513
Impaired Financing Receivables With Related Allowance [Member] | Residential real estate
Financing Receivable, Impaired [Line Items]
Current balance	1,033		1,033		1,056
Contractual Principal Balance	1,033		1,033		1,063
Related Allowance	160		160		160
Average current balance	1,036	1,067	1,043	1,126
Impaired Financing Receivables With Related Allowance [Member] | Home equity
Financing Receivable, Impaired [Line Items]
Current balance	100		100		100
Contractual Principal Balance	100		100		100
Related Allowance	2		2		2
Average current balance	100	101	100	101
Impaired Financing Receivables With Related Allowance [Member] | Installment
Financing Receivable, Impaired [Line Items]
Current balance	0		0		0
Contractual Principal Balance	0		0		0
Related Allowance	0		0		0
Average current balance	0	0	0	0
Impaired Financing Receivables With Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Current balance					4,444
Contractual Principal Balance					4,452
Related Allowance					$ 779
Average current balance	$ 3,726	$ 3,652	$ 3,410	$ 5,203

LOANS AND LEASES - Changes in O

LOANS AND LEASES - Changes in Other Real Estate Owned (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	$ 1,853	$ 5,961	$ 2,781	$ 6,284
Additions	818	1,794	2,992	4,044
Disposals	(298)	(4,505)	(3,138)	(6,797)
Write-downs	455	134	717	415
Balance at end of period	1,918	3,116	1,918	3,116
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Additions	79	1,559	1,269	1,731
Disposals	(181)	(3,684)	(2,611)	(5,291)
Write-downs	258	102	355	264
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Additions	739	235	1,723	2,313
Disposals	(117)	(821)	(527)	(1,506)
Write-downs	$ 197	$ 32	$ 362	$ 151

ALLOWANCE FOR LOAN AND LEASE _3

ALLOWANCE FOR LOAN AND LEASE LOSSES - Changes in the Allowance for Loan and Lease Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017
Allowance for loan and lease losses:
Balance at beginning of period	$ 54,076	$ 54,873	$ 54,021	$ 57,961
Provision for loan and lease losses	3,238	2,953	9,276	3,787
Loans charged-off	(2,063)	(4,499)	(11,554)	(11,747)
Recoveries	2,464	1,207	5,972	4,533
Total net charge-offs	(401)	3,292	5,582	7,214
Balance at end of period	57,715	54,534	57,715	54,534
Ending allowance on loans individually evaluated for impairment					$ 1,790	$ 779
Ending allowance on loans collectively evaluated for impairment					55,925	53,242
Ending allowance for loan and lease losses	54,076	54,873	57,715	54,534	57,715	54,021
Loans and Leases:
Ending balance of loans individually evaluated for impairment					62,681	41,627
Ending balance of loans collectively evaluated for impairment					8,784,695	5,971,556
Loans and Leases Receivable, Net of Deferred Income					8,847,376	6,013,183
Commercial
Allowance for loan and lease losses:
Balance at beginning of period	17,528	18,313	17,598	19,225
Provision for loan and lease losses	2,035	3,024	6,252	5,965
Loans charged-off	(232)	(4,122)	(5,473)	(8,930)
Recoveries	627	325	1,581	1,280
Total net charge-offs	(395)	3,797	3,892	7,650
Balance at end of period	19,958	17,540	19,958	17,540
Ending allowance on loans individually evaluated for impairment					1,562	169
Ending allowance on loans collectively evaluated for impairment					18,396	17,429
Ending allowance for loan and lease losses	17,528	18,313	19,958	19,225	19,958	17,598
Loans and Leases:
Ending balance of loans individually evaluated for impairment					11,985	7,331
Ending balance of loans collectively evaluated for impairment					2,414,605	1,905,412
Loans and Leases Receivable, Net of Deferred Income					2,426,590	1,912,743
Lease financing
Allowance for loan and lease losses:
Balance at beginning of period	797	550	675	716
Provision for loan and lease losses	287	507	408	340
Loans charged-off	0	0	0	0
Recoveries	0	0	1	1
Total net charge-offs	0	0	(1)	(1)
Balance at end of period	1,084	1,057	1,084	1,057
Ending allowance on loans individually evaluated for impairment					0	0
Ending allowance on loans collectively evaluated for impairment					1,084	675
Ending allowance for loan and lease losses	797	550	675	716	1,084	675
Loans and Leases:
Ending balance of loans individually evaluated for impairment					0	82
Ending balance of loans collectively evaluated for impairment					95,317	89,265
Loans and Leases Receivable, Net of Deferred Income					95,317	89,347
Construction real estate
Allowance for loan and lease losses:
Balance at beginning of period	3,985	3,416	3,577	3,282
Provision for loan and lease losses	(114)	(178)	294	(133)
Loans charged-off	0	0	0	0
Recoveries	146	0	146	89
Total net charge-offs	(146)	0	(146)	(89)
Balance at end of period	4,017	3,238	4,017	3,238
Ending allowance on loans individually evaluated for impairment					0	0
Ending allowance on loans collectively evaluated for impairment					4,017	3,577
Ending allowance for loan and lease losses	3,985	3,416	4,017	3,238	4,017	3,577
Loans and Leases:
Ending balance of loans individually evaluated for impairment					10	29
Ending balance of loans collectively evaluated for impairment					565,067	467,701
Loans and Leases Receivable, Net of Deferred Income					565,077	467,730
Commercial real estate
Allowance for loan and lease losses:
Balance at beginning of period	20,511	21,717	20,930	26,540
Provision for loan and lease losses	959	(1,003)	1,155	(6,510)
Loans charged-off	(902)	(58)	(3,156)	(1,028)
Recoveries	786	585	2,425	2,239
Total net charge-offs	116	(527)	731	(1,211)
Balance at end of period	21,354	21,241	21,354	21,241
Ending allowance on loans individually evaluated for impairment					66	448
Ending allowance on loans collectively evaluated for impairment					21,288	20,482
Ending allowance for loan and lease losses	20,511	21,717	21,354	26,540	21,354	20,930
Loans and Leases:
Ending balance of loans individually evaluated for impairment					28,390	21,542
Ending balance of loans collectively evaluated for impairment					3,839,753	2,468,549
Loans and Leases Receivable, Net of Deferred Income					3,868,143	2,490,091
Residential real estate
Allowance for loan and lease losses:
Balance at beginning of period	4,668	5,016	4,683	3,208
Provision for loan and lease losses	50	(243)	136	1,781
Loans charged-off	(145)	(23)	(342)	(307)
Recoveries	71	70	167	138
Total net charge-offs	74	(47)	175	169
Balance at end of period	4,644	4,820	4,644	4,820
Ending allowance on loans individually evaluated for impairment					160	160
Ending allowance on loans collectively evaluated for impairment					4,484	4,523
Ending allowance for loan and lease losses	4,668	5,016	4,644	4,820	4,644	4,683
Loans and Leases:
Ending balance of loans individually evaluated for impairment					15,310	7,932
Ending balance of loans collectively evaluated for impairment					917,652	463,459
Loans and Leases Receivable, Net of Deferred Income					932,962	471,391
Home equity
Allowance for loan and lease losses:
Balance at beginning of period	4,801	4,138	4,935	3,043
Provision for loan and lease losses	63	819	(60)	2,150
Loans charged-off	(351)	(71)	(978)	(635)
Recoveries	419	110	1,035	438
Total net charge-offs	(68)	(39)	(57)	197
Balance at end of period	4,932	4,996	4,932	4,996
Ending allowance on loans individually evaluated for impairment					2	2
Ending allowance on loans collectively evaluated for impairment					4,930	4,933
Ending allowance for loan and lease losses	4,801	4,138	4,932	3,043	4,932	4,935
Loans and Leases:
Ending balance of loans individually evaluated for impairment					6,654	4,456
Ending balance of loans collectively evaluated for impairment					809,479	489,148
Loans and Leases Receivable, Net of Deferred Income					816,133	493,604
Installment
Allowance for loan and lease losses:
Balance at beginning of period	290	355	307	388
Provision for loan and lease losses	(288)	(80)	(201)	(52)
Loans charged-off	(43)	(24)	(277)	(199)
Recoveries	351	74	481	188
Total net charge-offs	(308)	(50)	(204)	11
Balance at end of period	310	325	310	325
Ending allowance on loans individually evaluated for impairment					0	0
Ending allowance on loans collectively evaluated for impairment					310	307
Ending allowance for loan and lease losses	290	355	310	388	310	307
Loans and Leases:
Ending balance of loans individually evaluated for impairment					332	255
Ending balance of loans collectively evaluated for impairment					97,081	41,331
Loans and Leases Receivable, Net of Deferred Income					97,413	41,586
Credit card
Allowance for loan and lease losses:
Balance at beginning of period	1,496	1,368	1,316	1,559
Provision for loan and lease losses	246	107	1,292	246
Loans charged-off	(390)	(201)	(1,328)	(648)
Recoveries	64	43	136	160
Total net charge-offs	326	158	(1,192)	(488)
Balance at end of period	1,416	1,317	1,416	1,317
Ending allowance on loans individually evaluated for impairment					0	0
Ending allowance on loans collectively evaluated for impairment					1,416	1,316
Ending allowance for loan and lease losses	$ 1,496	$ 1,368	$ 1,316	$ 1,317	1,416	1,316
Loans and Leases:
Ending balance of loans individually evaluated for impairment					0	0
Ending balance of loans collectively evaluated for impairment					45,741	46,691
Loans and Leases Receivable, Net of Deferred Income					$ 45,741	$ 46,691

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS GOODWILL AND OTHER INTANGIBLE ASSETS--Schedule of Goodwill (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Goodwill [Roll Forward]
Balance at beginning of period	$ 204,084	$ 204,084	$ 204,084
Goodwill	676,949	$ 0	0
Balance at end of period	$ 881,033		$ 204,084

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS--Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Goodwill			$ 676,949	$ 0	$ 0
Goodwill	$ 881,033		881,033		204,084	$ 204,084
Intangible Assets, Net (Excluding Goodwill)	53,300		53,300		5,300
Finite-Lived Core Deposits, Gross	40,200		40,200		$ 3,300
Finite-Lived Intangible Assets, Amortization Expense	$ 2,500	$ 300	$ 5,100	$ 1,000
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization method			accelerated basis
Estimated weighted average life (in years)			9 years 1 month 6 days

BORROWINGS Borrowings - - Addit

BORROWINGS Borrowings - - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
FHLB short-term borrowings	$ 1,170,800	$ 742,300
Line of Credit Facility, Maximum Borrowing Capacity	30,000
Commitments outstanding to extend credit	0	0
Short-term Debt	1,294,252	814,565
Long-term Debt	570,037	119,654
Subordinated debt	$ 120,000
Subordinated Borrowing, Interest Rate	5.125%
Subordinated debt	$ 177,887	120,000
Advances from Federal Home Loan Banks	$ 400,046	$ 241
Federal Home Loan Bank	2.09%	1.09%
Subordinated Debt [Member]
Subordinated debt	$ 49,500
Private Placement [Member]
Subordinated debt	$ 8,400
Debt Instrument, Interest Rate, Effective Percentage	6.94%
Private Placement [Member]
DebtInstrumentMinimumCallablePeriod	5 years
Subordinated Debt [Member]
Debt Instrument Maturity Period	30 years
DebtInstrumentMinimumCallablePeriod	5 years

BORROWINGS - Schedule of Long-t

BORROWINGS - Schedule of Long-term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Amount
Subordinated debt	$ 177,887	$ 120,000
FHLB long-term advances	400,046	241
Capital loan with municipality	775	775
Total long-term debt	$ 570,037	$ 119,654
Average Rate [Abstract]
Debt, Weighted Average Interest Rate	5.13%	5.13%
Federal Home Loan Bank	2.09%	1.09%
Weighted average rate on other long-term debt	0.00%	0.00%
Total long-term debt	3.06%	5.14%
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ (8,671)	$ (1,362)

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Other Comprehensive Income (Loss), before Reclassification Adjustments and Tax [Abstract]
Unrealized gain (loss) on investment securities	$ (13,138)	$ 2,612	$ (37,130)	$ 12,614
Unrealized gain (loss) on derivatives	130	202	535	607
Retirement obligation	0	0	0	0
Total	(13,008)	2,814	(36,595)	13,221
Other Comprehensive Income (Loss) Reclassifications before Tax [Abstract]
Unrealized gain (loss) on investment securities	(167)	276	(197)	1,630
Unrealized gain (loss) on derivatives	0	0	0	0
Retirement obligation	(452)	(335)	(1,323)	(1,005)
Total	(619)	(59)	(1,520)	625
Transactions Pre-tax
Unrealized gain (loss) on investment securities	(12,971)	2,336	(36,933)	10,984
Unrealized gain (loss) on derivatives	130	202	535	607
Unfunded pension obligation	452	335	1,323	1,005
Total	(12,389)	2,873	(35,075)	12,596
Transactions Tax-effect
Unrealized gain (loss) on investment securities	2,786	(835)	7,940	(3,920)
Unrealized gain (loss) on derivatives	(31)	(73)	(121)	(222)
Retirement obligation	(105)	(122)	(159)	(390)
Total	2,650	(1,030)	7,660	(4,532)
Transactions Net of tax
Unrealized gain (loss) on investment securities	(10,185)	1,501	(28,993)	7,064
Unrealized gain (loss) on derivatives	99	129	414	385
Retirement obligation	347	213	1,164	615
Total	(9,739)	1,843	(27,415)	8,064
Stranded Tax Effects
Unrealized gain (loss) on investment securities			(189)
Unrealized gain (loss) on Derivatives			(124)
Retirement obligation			(4,779)
Total			(5,092)
Balances Net of tax
Unrealized gain (loss) on investment securities	(29,364)	2,515	(29,364)	2,515	$ (19,179)	$ (182)	$ 1,014	$ (4,549)
Unrealized gain (loss) on cash flow hedges	(287)	(706)	(287)	(706)	(386)	(577)	(835)	(1,091)
Retirement obligation	(23,246)	(22,188)	(23,246)	(22,188)	(23,593)	(19,631)	(22,401)	(22,803)
Total	$ (52,897)	$ (20,379)	(52,897)	(20,379)	$ (43,158)	$ (20,390)	$ (22,222)	$ (28,443)
Accumulated other comprehensive income (loss)
Transactions Net of tax
Total			$ (27,415)	$ 8,064

ACCUMULATED OTHER COMPREHENSI_4

ACCUMULATED OTHER COMPREHENSIVE INCOME AMOUNT RECLASSIFIED FROM ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Other Accumulated Comprehensive income reclassified from AOCI [Line Items]
Unrealized gain (loss) on investment securities	$ (167)	$ 276	$ (197)	$ 1,630
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	104	103	310	310
Defined Benefit Plan, Amortization of Gain (Loss)	(556)	(438)	(1,633)	(1,315)
Other Comprehensive Income, Reclassification, Amortization of Defined Benefit Plans items, Pre-tax	(452)	(335)	(1,323)	(1,005)
Total	$ (619)	$ (59)	$ (1,520)	$ 625

DERIVATIVES - Additional Inform

DERIVATIVES - Additional Information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)entity	Dec. 31, 2017USD ($)entity
Derivative [Line Items]
Maximum derivative notional position as a percentage of assets	35.00%
Maximum credit exposure as a percentage of capital	3.00%
Maximum single counterparty credit risk exposure	$ 20,000
Inerest-bearing deposit liability	$ 2,624,586	$ 1,674,080
Number of counterparties | entity	13	13
Derivative Asset	$ 33,286	$ 12,682
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	33,278	12,687
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	20,800	12,300
Other Credit Derivatives [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	20,800	15,400
Credit Risk Derivative Liabilities, at Fair Value		100
Credit Risk Contract [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	150,100	95,900
Credit Risk Derivative Liabilities, at Fair Value		100
Accrued interest and other liabilities | Derivative [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	1,300,000	837,500
Derivative Asset	$ (26,000)
Derivative Financial Instruments, Liabilities, Fair Value Disclosure		$ 1,300

DERIVATIVES - Summary of Deriva

DERIVATIVES - Summary of Derivative Financial Instruments and Balances (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Inerest-bearing deposit liability	$ 2,624,586	$ 1,674,080
Derivative Asset	33,286	12,682
Estimate Fair Value Loss	(33,278)	(12,687)
Other Credit Derivatives [Member]
Derivatives, Fair Value [Line Items]
Inerest-bearing deposit liability	20,800	15,400
Credit Risk Derivative Liabilities, at Fair Value		100
Fair Value Hedges | Matched interest rate swaps | Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Inerest-bearing deposit liability	1,312,293	837,040
Derivative Asset	29,240	5,529
Estimate Fair Value Loss	(4,038)	(7,158)
Fair Value Hedges | Matched interest rate swaps | Accrued interest and other assets
Derivatives, Fair Value [Line Items]
Inerest-bearing deposit liability	1,312,293	837,040
Derivative Asset	4,046	7,153
Estimate Fair Value Loss	$ (29,240)	$ (5,529)

DERIVATIVES DERIVATIVES - Discl

DERIVATIVES DERIVATIVES - Disclosure by Type of Financial Instrument (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Credit Risk Contract [Member]
Derivatives, Fair Value [Line Items]
Credit Risk Derivative Liabilities, at Fair Value		$ 100
Fair Value Hedges | Matched interest rate swaps | Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of recognized liabilities	$ 33,286	12,687
Derivative Liability, Fair Value, Gross Asset	(4,900)	2,279
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 28,386	$ 14,966

DERIVATIVES - Derivative Financ

DERIVATIVES - Derivative Financial Instruments, Average Remaining Maturity and the Weighted-Average Interest Rates being Paid and Received (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional Value	$ 2,624,586	$ 1,674,080
Interest Rate Swap
Derivative [Line Items]
Notional Value	$ 2,624,586
Average Maturity (years)	4 years 7 months 6 days
Fair Value	$ 8
Weighted-Average Rate Receive	4.42%
Weighted-Average Rate Pay	4.42%
Interest Rate Swap | Derivative Financial Instruments Receive Fixed Pay Variable
Derivative [Line Items]
Notional Value	$ 1,312,293
Average Maturity (years)	4 years 7 months 6 days
Fair Value	$ (25,194)
Weighted-Average Rate Receive	4.62%
Weighted-Average Rate Pay	4.23%
Interest Rate Swap | Derivative Financial Instruments Receive Variable Pay Fixed
Derivative [Line Items]
Notional Value	$ 1,312,293
Average Maturity (years)	4 years 7 months 6 days
Fair Value	$ 25,202
Weighted-Average Rate Receive	4.23%
Weighted-Average Rate Pay	4.62%

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Commitments and Contingencies Disclosure [Line Items]
Reserves for unfunded commitments	$ 700		$ 700		$ 500
Commitments outstanding to extend credit	0		0		0
Letters of credit issued to guarantee performance of a client to a third party	34,000		34,000		25,300
Affordable Housing Program Obligation	42,200		42,200		35,900
Affordable housing contingent commitment	0		0		0
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	2,900		2,900		3,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	2,900		2,900		3,000
Amortization Method Qualified Affordable Housing Project Investments, Amortization	1,400	$ 1,000	4,300	$ 3,200
Estimated Litigation Liability	0		0		0
Loans and Leases Receivable, Commitments, Fixed Rates			202,700		44,300
Loans and Leases Receivable, Commitments, Variable Rates			$ 2,700,000		2,000,000
Loan Commitments, Fixed Interest Rate Range, Minimum			0.00%
Loan Commitments, Fixed Interest Rate Range, Maximum			21.00%
Loan Commitments, Fixed Rate, Maturities, Minimum			1 year
Loan Commitments, Fixed Rate, Maturities, Maximum			30 years
Commitments to Extend Credit
Commitments and Contingencies Disclosure [Line Items]
Commitments outstanding to extend credit	2,900,000		$ 2,900,000		$ 2,100,000
Affordable housing investment [Member]
Commitments and Contingencies Disclosure [Line Items]
Low-income housing tax credit	1,300	800	3,600	2,400
Historic tax credit [Member]
Commitments and Contingencies Disclosure [Line Items]
Low-income housing tax credit	$ 100	$ 100	$ 400	$ 400

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expense	$ 12,859	$ 11,199	$ 29,839	$ 32,884
Effective tax rate	20.20%	31.10%	20.20%	31.40%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%	35.00%
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 2,900		$ 2,900		$ 2,900

EMPLOYEE BENEFIT PLANS - Additi

EMPLOYEE BENEFIT PLANS - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Retirement Benefits [Abstract]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	$ 0		$ 0
Payment for Pension Benefits			0		$ 0
Pension Cost (Reversal of Cost)	$ 339,000	$ (319,000)	$ 521,000	$ (956,000)

EMPLOYEE BENEFIT PLANS EMPLOYEE

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS - Employee benefit plan amounts recognized in the Consolidated Balance Sheets and Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Retirement Benefits [Abstract]
Service cost	$ 1,736	$ 1,238	$ 4,766	$ 3,715
Interest cost	601	589	1,792	1,767
Expected return on plan assets	(2,450)	(2,481)	(7,360)	(7,443)
Amortization of prior service cost	(104)	(103)	(310)	(310)
Defined Benefit Plan, Amortization of Gain (Loss)	556	438	1,633	1,315
Net periodic benefit cost (income)	$ 339	$ (319)	$ 521	$ (956)

REVENUE RECOGNITION REVENUE REC

REVENUE RECOGNITION REVENUE RECOGNITION (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Revenue Recognition [Abstract]
Interchange income	$ 8.6	$ 22.1
Credit card expense	$ 3.4	$ 8.1

EARNINGS PER COMMON SHARE - Com

EARNINGS PER COMMON SHARE - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator for basic and diluted earnings per share -income available to common shareholders:
Net income	$ 50,657	$ 24,826	$ 117,581	$ 71,976
Denominator for basic earnings per share - weighted average shares	97,411,201	61,577,619	85,602,116	61,507,160
Effect of dilutive securities -
Employee stock awards	536,760	552,774	515,566	617,128
Warrants	536,267	59,244	522,245	61,586
Denominator for diluted earnings per share - adjusted weighted average shares	98,484,228	62,189,637	86,639,927	62,185,874
Basic	$ 0.52	$ 0.40	$ 1.37	$ 1.17
Diluted	$ 0.51	$ 0.40	$ 1.36	$ 1.16

EARNINGS PER COMMON SHARE - Add

EARNINGS PER COMMON SHARE - Additional Information (Details) - $ / shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share Disclosure [Line Items]
Class of Warrant or Right, Outstanding	2	1
Investment Warrants, Exercise Price	$ 12.09
Antidilutive Warrants
Earnings Per Share Disclosure [Line Items]
Stock options and warrants with an exercise price greater than the average market price of the common shares not included in the computation of net income per diluted share	17,172	105,832
Antidilutive Stock Options
Earnings Per Share Disclosure [Line Items]
Stock options and warrants with an exercise price greater than the average market price of the common shares not included in the computation of net income per diluted share	0	0
MainSource [Member]
Earnings Per Share Disclosure [Line Items]
Investment Warrants, Exercise Price	$ 10.71
MainSource [Member] | Antidilutive Warrants
Earnings Per Share Disclosure [Line Items]
Stock options and warrants with an exercise price greater than the average market price of the common shares not included in the computation of net income per diluted share	793,520

FAIR VALUE DISCLOSURES - Estima

FAIR VALUE DISCLOSURES - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	$ 33,278	$ 12,687
Financial assets
Investment securities held-to-maturity	434,369	654,008
Other investments	115,757	53,140
Deposits
Noninterest-bearing	2,375,845	1,662,058
Savings	3,134,944	2,462,420
Time	1,957,574	1,317,105
Carrying value
Financial assets
Cash and short-term investments	222,277	184,624
Investment securities held-to-maturity	434,369	654,008
Other investments	115,757	53,140
Loans held for sale	13,277	11,502
Loans and leases	8,789,661	5,959,162
Interest Receivable	41,755	24,496
Deposits
Deposits	9,752,634	6,895,046
Short-term borrowings	1,294,252	814,565
Long-term debt	570,037	119,654
Interest Payable	10,517	5,104
Fair value
Financial assets
Cash and short-term investments	222,277	184,624
Investment securities held-to-maturity	422,638	653,101
Loans held for sale	13,277	11,502
Loans and leases	8,737,769	6,006,656
Interest Receivable	41,755	24,496
Deposits
Deposits	9,722,689	6,884,615
Short-term borrowings	1,294,252	814,565
Long-term debt	547,569	117,908
Interest Payable	10,517	5,104
Fair Value, Inputs, Level 1 [Member] | Fair value
Financial assets
Cash and short-term investments	222,277	184,624
Investment securities held-to-maturity	0	0
Loans held for sale	0	0
Loans and leases	0	0
Interest Receivable	0	0
Deposits
Deposits	0	0
Short-term borrowings	1,294,252	814,565
Long-term debt	0	0
Interest Payable	2,963	204
Fair Value, Inputs, Level 2 [Member] | Fair value
Financial assets
Cash and short-term investments	0	0
Investment securities held-to-maturity	422,638	653,101
Loans held for sale	13,277	11,502
Loans and leases	0	0
Interest Receivable	13,674	8,265
Deposits
Deposits	9,722,689	6,884,615
Short-term borrowings	0	0
Long-term debt	547,569	117,908
Interest Payable	7,554	4,900
Fair Value, Inputs, Level 3 [Member] | Fair value
Financial assets
Cash and short-term investments	0	0
Investment securities held-to-maturity	0	0
Loans held for sale	0	0
Loans and leases	8,737,769	6,006,656
Interest Receivable	28,081	16,231
Deposits
Deposits	0	0
Short-term borrowings	0	0
Long-term debt	0	0
Interest Payable	$ 0	$ 0

FAIR VALUE DISCLOSURES - Summar

FAIR VALUE DISCLOSURES - Summary of Financial Assets and Liabilities Measure at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Derivatives	$ 33,286	$ 12,682
Investment securities available-for-sale	2,626,726	1,349,408
Liabilities
Derivatives	33,278	12,687
Fair Value, Measurements, Recurring
Assets
Derivatives	33,806	12,757
Investment securities available-for-sale	2,626,726	1,349,408
Total	2,660,532	1,362,165
Liabilities
Derivatives	33,321	12,755
Fair Value, Measurements, Recurring | Fair Value Measurements Using Level 1
Assets
Derivatives	0	0
Investment securities available-for-sale	95	2,969
Total	95	2,969
Liabilities
Derivatives	0	0
Fair Value, Measurements, Recurring | Fair Value Measurements Using Level 2
Assets
Derivatives	33,806	12,757
Investment securities available-for-sale	2,626,631	1,346,439
Total	2,660,437	1,359,196
Liabilities
Derivatives	33,321	12,755
Fair Value, Measurements, Recurring | Fair Value Measurements Using Level 3
Assets
Derivatives	0	0
Investment securities available-for-sale	0	0
Total	0	0
Liabilities
Derivatives	$ 0	$ 0

FAIR VALUE DISCLOSURES - Summ_2

FAIR VALUE DISCLOSURES - Summary of Financial Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value Measurements Using Level 1
Assets
Impaired loans	$ 0	$ 0
Other Real Estate Owned, Fair Value Disclosure	0	0
Fair Value Measurements Using Level 2
Assets
Impaired loans	0	0
Other Real Estate Owned, Fair Value Disclosure	0	0
Fair Value Measurements Using Level 3
Assets
Impaired loans	2,816	2,671
Other Real Estate Owned, Fair Value Disclosure	$ 1,515	$ 1,086

BUSINESS COMBINATION BUSINESS C

BUSINESS COMBINATION BUSINESS COMBINATION - Additional Information (Details) - USD ($) $ in Thousands	Apr. 01, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Business Acquisition [Line Items]
Business Acquisition, Number Of Shares Received by Acquiree	1.3875
Business Combination, Consideration Transferred	$ 1,100,000	$ 1,061,956
Goodwill		676,949	$ 0	$ 0
Payments for Merger Related Costs		$ 33,300

BUSINESS COMBINATION BUSINESS_2

BUSINESS COMBINATION BUSINESS COMBINATIONS (Details) - USD ($) $ in Thousands	Apr. 01, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Business Acquisition [Line Items]
Cash consideration		$ 43
Stock consideration		1,045,876
Warrant consideration		14,460
Options consideration		1,577
Total purchase consideration	$ 1,100,000	1,061,956
Cash		71,734
Investment securities available-for-sale		901,008
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Held to Maturity Securities		171,423
Other investments		28,763
Loans		2,792,517
Premises and equipment		98,537
Intangible assets		42,887
Other assets		169,311
Assets held for sale		127,775
Total assets acquired		4,403,955
Deposits		3,264,038
Subordinated notes		49,027
FHLB advances		291,887
Other borrowings		205,620
Other liabilities		32,654
Liabilities held for sale		175,722
Total liabilities assumed		4,018,948	$ 0
Net identifiable assets		385,007
Goodwill		$ 676,949	$ 0	$ 0

BUSINESS COMBINATION Business A

BUSINESS COMBINATION Business Acquisition, Pro Forma Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Business Combinations [Abstract]
Business Acquisition, Pro Forma Revenue	$ 362,112	$ 334,736
Business Acquisition, Pro Forma Net Income (Loss)	$ 161,323	$ 93,293
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 1.66	$ 0.96
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 1.64	$ 0.95