First Financial Bancorp. (FFBC) 10-K22 Feb 192018 FY Annual reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information Document - USD ($)	12 Months Ended
Document and Entity Information Document - USD ($)	Dec. 31, 2018	Feb. 21, 2019	Jun. 30, 2018
DOCUMENT AND ENTITY INFORMATION [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Trading Symbol	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		98,389,491
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 2,938,239,000
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
ASSETS
Cash and due from banks	$ 236,221	$ 150,650
Interest-bearing deposits with other banks	37,738	33,974
Investment securities available-for-sale, at fair value (amortized cost $2,792,326 at December 31, 2018 and $1,348,227 at December 31, 2017)	2,779,255	1,349,408
Investment securities held-to-maturity (fair value $424,118 at December 31, 2018 and $653,101 at December 31, 2017)	429,328	654,008
Other investments	115,660	53,140
Loans held for sale	4,372	11,502
Loans and leases
Commercial & industrial	2,514,661	1,912,743
Lease financing	93,415	89,347
Construction real estate	548,935	467,730
Commercial real estate	3,754,681	2,490,091
Residential real estate	955,646	471,391
Home equity	817,282	493,604
Installment	93,212	41,586
Credit card	46,382	46,691
Total loans and leases	8,824,214	6,013,183
Less: Allowance for loan and lease losses	56,542	54,021
Net loans and leases	8,767,672	5,959,162
Premises and equipment	215,652	125,036
Goodwill	880,251	204,084
Other intangibles	40,805	3,786
Accrued interest and other assets	479,706	352,173
Total assets	13,986,660	8,896,923
Deposits
Interest-bearing demand	2,307,071	1,453,463
Savings	3,167,325	2,462,420
Time	2,173,564	1,317,105
Total interest-bearing deposits	7,647,960	5,232,988
Noninterest-bearing	2,492,434	1,662,058
Total deposits	10,140,394	6,895,046
Federal funds purchased	183,591	72,265
FHLB short-term borrowings	857,100	742,300
Total short-term borrowings	1,040,691	814,565
Long-term debt	570,739	119,654
Total borrowed funds	1,611,430	934,219
Accrued interest and other liabilities	156,587	136,994
Total liabilities	11,908,411	7,966,259
Shareholders' equity
Common stock - no par value	1,633,256	573,109
Retained earnings	600,014	491,847
Accumulated other comprehensive income (loss)	(44,408)	(20,390)
Treasury stock, at cost, 6,387,508 shares in 2018 and 6,661,644 shares in 2017	(110,613)	(113,902)
Total shareholders' equity	2,078,249	930,664
Total liabilities and shareholders’ equity	$ 13,986,660	$ 8,896,923

CONSOLIDATED BALANCE SHEETS CON

CONSOLIDATED BALANCE SHEETS CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Investment securities available-for-sale, cost	$ 2,792,326	$ 1,348,227
Investment securities held-to-maturity, market value	$ 424,118	$ 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	6,387,508	6,661,644

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest income
Loans and leases, including fees	$ 447,187	$ 280,111	$ 262,703
Investment securities
Taxable	79,076	50,568	43,103
Tax-exempt	13,428	5,918	4,535
Total interest on investment securities	92,504	56,486	47,638
Other earning assets	691	(3,524)	(4,391)
Total interest income	540,382	333,073	305,950
Interest expense
Deposits	56,962	35,182	22,613
Short-term borrowings	18,033	8,193	4,506
Long-term borrowings	16,152	6,153	6,160
Total interest expense	91,147	49,528	33,279
Net interest income	449,235	283,545	272,671
Provision for loan and lease losses	14,586	3,582	10,140
Net interest income after provision for loan and lease losses	434,649	279,963	262,531
Noninterest income
Service charges on deposit accounts	35,108	19,775	18,933
Investment Banking, Advisory, Brokerage, and Underwriting Fees and Commissions	15,082	14,073	13,200
Bankcard income	20,245	13,298	12,132
Client derivative fees	7,682	6,418	4,570
Net gain from sales of loans	6,071	5,169	6,804
Net gain (loss) on sales of investment securities	(161)	1,649	234
Other	19,355	15,760	13,728
Total noninterest income	103,382	76,142	69,601
Noninterest expenses
Salaries and employee benefits	188,990	137,240	128,549
Net occupancy	24,215	17,397	18,329
Furniture and equipment	14,908	8,443	8,663
Data processing	28,077	14,022	11,406
Marketing	7,598	3,201	3,965
Communication	3,167	1,819	1,889
Professional services	12,272	15,023	6,303
State intangible tax	4,152	2,655	2,034
FDIC assessments	3,969	3,944	4,293
Loss (gain) - other real estate owned	373	642	(1,212)
Other	36,089	35,556	17,182
Total noninterest expenses	323,810	239,942	201,401
Income before income taxes	214,221	116,163	130,731
Income tax expense	41,626	19,376	42,205
Net income	$ 172,595	$ 96,787	$ 88,526
Earnings per common share
Basic	$ 1.95	$ 1.57	$ 1.45
Diluted	$ 1.93	$ 1.56	$ 1.43
Average common shares outstanding - basic	88,582,090	61,529,460	61,206,093
Average common shares outstanding - diluted	89,614,205	62,171,590	61,985,422

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 172,595	$ 96,787	$ 88,526
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on debt securities arising during the period	(11,229)	4,367	384
Change in retirement obligation	(8,180)	3,172	1,245
Unrealized gain (loss) on derivatives	484	514	508
Other comprehensive income (loss)	(18,925)	8,053	2,137
Comprehensive income	$ 153,670	$ 104,840	$ 90,663

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
Balances at January 1, 2016 at Dec. 31, 2015	$ 809,376	$ 571,155	$ 388,240	$ (30,580)	$ (119,439)
Balances at January 1, 2016 at Dec. 31, 2015		68,730,731			(7,089,051)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	88,526		88,526
Other comprehensive loss	2,137			2,137
Cash dividends declared:
Common stock at $0.76 per share in 2018, $0.68 per share in 2017, and $0.64 per share in 2016	(39,578)		(39,578)
Common stock issued in connection with business combinations	$ 0
Treasury Stock, Shares, Acquired	0
Adjustments to Additional Paid in Capital, Other	$ 0	$ (1,507)			$ 1,507
Stock Issued During Period, Shares, Other					89,383
Excess tax benefit on share-based compensation	264	264
Exercise of stock options, net of shares purchased (in shares)					65,515
Exercise of stock options, net of shares purchased	726	(379)			$ 1,105
Restricted stock awards, net of forfeitures (in shares)					182,974
Restricted stock awards, net of forfeitures	(1,581)	(4,505)			$ 2,924
Share-based compensation expense	5,354	$ 5,354
Ending Balances (in shares) at Dec. 31, 2016		68,730,731			(6,751,179)
Ending Balances at Dec. 31, 2016	865,224	$ 570,382	437,188	(28,443)	$ (113,903)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	96,787		96,787
Other comprehensive loss	8,053			8,053
Cash dividends declared:
Common stock at $0.76 per share in 2018, $0.68 per share in 2017, and $0.64 per share in 2016	(42,128)		(42,128)
Common stock issued in connection with business combinations	$ 0
Treasury Stock, Shares, Acquired	0
Adjustments to Additional Paid in Capital, Other	$ 0	(99)			$ 99
Stock Issued During Period, Shares, Other					5,843
Exercise of stock options, net of shares purchased (in shares)					58,212
Exercise of stock options, net of shares purchased	75	(912)			$ 987
Restricted stock awards, net of forfeitures (in shares)					25,480
Restricted stock awards, net of forfeitures	(2,793)	(1,708)			$ (1,085)
Share-based compensation expense	5,446	$ 5,446
Ending Balances (in shares) at Dec. 31, 2017		68,730,731			(6,661,644)
Ending 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		5,093	(5,093)
Net income	172,595		172,595
Other comprehensive loss	(18,925)			(18,925)
Cash dividends declared:
Common stock at $0.76 per share in 2018, $0.68 per share in 2017, and $0.64 per share in 2016	(69,521)		(69,521)
Stock Issued During Period, Shares, Acquisitions		35,551,063
Common stock issued in connection with business combinations	1,043,424	$ 1,043,424
Treasury Stock, Shares, Acquired
Treasury Stock, Value, Acquired, Cost Method
Stock Options and Warrants Acquired And Converted Pursuant To Acquisition	16,037	16,037
Adjustments to Additional Paid in Capital, Other	$ 0	(1,120)			$ 1,120
Stock Issued During Period, Shares, Other					65,354
Exercise of stock options, net of shares purchased (in shares)	32,941				32,941
Exercise of stock options, net of shares purchased	$ 284	(282)			$ 566
Restricted stock awards, net of forfeitures (in shares)					175,841
Restricted stock awards, net of forfeitures	(2,528)	(4,131)			$ 1,603
Share-based compensation expense	6,219	$ 6,219
Ending Balances (in shares) at Dec. 31, 2018		104,281,794			(6,387,508)
Ending Balances at Dec. 31, 2018	$ 2,078,249	$ 1,633,256	$ 600,014	$ (44,408)	$ (110,613)

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Common Stock, Dividends, Per Share, Declared	$ 0.78	$ 0.68	$ 0.64

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income	$ 172,595	$ 96,787	$ 88,526
Adjustments to reconcile net income to net cash provided by operating activities
Provision for loan and lease losses	14,586	3,582	10,140
Depreciation and amortization	24,171	12,645	13,037
Stock-based compensation expense	6,219	5,446	5,354
Pension expense (income)	859	(628)	(1,153)
Net amortization (accretion) on investment securities	10,846	10,798	8,476
Net (gains) losses on sales of investments securities	161	(1,649)	(234)
Originations of loans held for sale	(157,771)	(157,796)	(232,526)
Net (gains) losses on sales of loans held for sale	(6,071)	(5,169)	(6,804)
Proceeds from sales of loans held for sale	167,374	163,300	246,829
Deferred income taxes	6,267	(4,488)	346
Life Insurance, Corporate or Bank Owned, Change in Value	5,454	3,792	186
Decrease (increase) in interest receivable	(3,808)	(5,707)	(1,456)
Decrease in indemnification asset	(1,900)	(10,117)	(5,613)
(Decrease) increase in interest payable	5,207	55	46
Decrease (increase) in other assets	34,360	(21,455)	(1,108)
(Decrease) increase in other liabilities	(10,043)	21,478	7,700
Net cash provided by (used in) operating activities	261,398	123,524	142,600
Investing activities
Proceeds from sales of investment securities available-for-sale	290,745	189,962	206,990
Proceeds from calls, paydowns and maturities of securities available-for-sale	387,351	224,690	186,132
Purchases of securities available-for-sale	(852,131)	(723,131)	(396,984)
Proceeds from Sale of Held-to-maturity Securities	0	0	4,862
Proceeds from calls, paydowns and maturities of securities held-to-maturity	36,671	121,903	127,021
Purchases of securities held-to-maturity	(14,014)	(23,402)	(11,196)
Purchases of other investment securities	(31,385)	(2,353)	(4,239)
Net decrease (increase) in interest-bearing deposits with other banks	(3,764)	48,476	(48,716)
Net decrease (increase) in loans and leases	(28,577)	(266,043)	(376,848)
Proceeds from disposal of other real estate owned	3,797	6,983	9,356
Purchases of premises and equipment	(18,228)	(6,537)	(9,726)
Cash Acquired from Acquisition	64,895	0	0
Payments for (Proceeds from) Businesses and Interest in Affiliates	(41,197)	0	0
Net cash provided by (used in) investing activities	(205,837)	(429,452)	(313,348)
Financing activities
Net (decrease) increase in total deposits	(18,690)	369,258	346,164
Net (decrease) increase in short-term borrowings	30,531	6,653	(130,513)
Payments on long-term borrowings	(52,460)	(94)	(86)
Proceeds from FHLBank Borrowings, Financing Activities	150,000	0	0
Cash dividends paid on common stock	(79,655)	(41,178)	(39,125)
Proceeds from exercise of stock options	284	341	801
Excess tax benefit on share-based compensation	0	0	264
Net cash provided by (used in) financing activities	30,010	334,980	177,505
Cash and due from banks
Net (decrease) increase in Cash and due from banks	85,571	29,052	6,757
Cash and due from banks at beginning of year	150,650	121,598	114,841
Cash and due from banks at end of year	236,221	150,650	121,598
Supplemental disclosures
Interest paid	84,125	49,474	33,233
Income taxes paid	16,004	38,329	37,566
Real Estate Owned, Transfer to Real Estate Owned excluding acquired OREO	1,821
Acquisition of other real estate owned through foreclosure	3,182	4,119	2,872
Issuance of restricted stock awards	8,797	6,416	5,759
Securities transferred from AFS to HTM	372,128	0	0
Common stock issued in bank acquisitions	1,043,424	0	0
Supplemental schedule for investing activities
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Assets, Net Of Purchase Consideration	3,342,781	0	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	4,018,948	0	0
Goodwill	$ 676,167	$ 0	$ 0

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Notes)	12 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Notes)	Dec. 31, 2018
Summary of Significant Accounting Policies [Abstract]
BASIS OF PRESENTATION	Summary of Significant Accounting Policies 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 years' amounts have been made to conform to current year presentation. Such reclassifications had no effect on net earnings. Use of estimates. The preparation of Consolidated 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. Actual realized amounts could differ materially from those estimates. Cash and due from banks. Cash and due from banks consist of currency, coin and cash items due from banks. Cash items due from banks include noninterest bearing deposits held at other banks. Investment securities. First Financial classifies debt securities into three categories: HTM, trading and AFS. Management classifies investment securities into the appropriate category at the time of purchase and re-evaluates that classification as deemed appropriate. Investment securities are classified as HTM when First Financial has the positive intent and ability to hold the securities to maturity. HTM securities are recorded at amortized cost. Investment securities classified as trading are held principally for resale in the near-term and are recorded at fair value. Fair value is determined using quoted market prices. Gains or losses on trading securities, both realized and unrealized, are reported in noninterest income. Investment securities not classified as either HTM or trading are classified as AFS. AFS securities are recorded at fair value, with the unrealized gains and losses, net of tax, reported as a separate component of accumulated other comprehensive income (loss) in shareholders' equity. The amortized cost of investment securities classified as either HTM or AFS is adjusted for amortization of premiums and accretion of discounts to maturity, or in the case of mortgage-backed securities, over the estimated life of the security. Such amortization and accretion are considered an adjustment to the yield on the security and included in interest income from investments. Interest and dividends are included in interest income from investment securities in the Consolidated Statements of Income. Realized gains and losses are based on the amortized cost of the security sold using the specific identification method. AFS and HTM securities are reviewed quarterly for potential impairment. In performing this review, management considers the length of time and extent to which the fair value of the security has been less than amortized cost, the financial condition and near-term prospects of the issuer and the ability and intent of First Financial to hold the security for a period sufficient to allow for any anticipated recovery in fair value. If the fair value of a security is less than the amortized cost and the impairment is determined to be other-than-temporary, the security is written down, establishing a new and reduced cost basis. The related charge is recorded in the Consolidated Statements of Income. Other investments. Other investments include holdings in FRB stock and FHLB stock, which are both carried at cost, as well as equity securities which are carried at fair value. Changes in the fair value of equity securities are recorded Other noninterest income in the Consolidated Statements of Income. Loans held for sale. Loans held for sale consist of residential real estate loans newly originated for the purpose of sale to third parties, and in certain circumstances, loans previously originated that have been specifically identified by management for sale based on predetermined criteria. Loans originated to held for sale status are carried at fair value. Any subsequent change in the carrying value of transferred loans, not to exceed original cost, is recorded in the Consolidated Statements of Income. First Financial sells loans with servicing retained or released depending on pricing and market conditions. Loans and leases. Loans and leases for which First Financial has the intent and ability to hold for the foreseeable future, or until maturity or payoff, are classified in the Consolidated Balance Sheets as loans and leases. Loans and leases are carried at the principal amount outstanding, net of unamortized deferred loan origination fees and costs, and net of unearned income. Loan origination and commitment fees received, as well as certain direct loan origination costs paid, are deferred, and the net amount is amortized as an adjustment to the related loan's yield. Interest income on loans and leases is recorded on an accrual basis. 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 classified as nonaccrual are applied as a reduction to the carrying value of the loan. A loan may return to accrual status if collection of future principal and interest payments is no longer doubtful. 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. Accretion of the difference between the carrying value of the loans and the expected cash flows (accretable difference) is recognized on purchased impaired loans through interest income. Acquired loans outside of the scope of FASB ASC Topic 310-30 are accounted for under FASB ASC Topic 310-20, Receivables-Nonrefundable Fees and Costs. Discounts created when the loans were recorded at their estimated fair values at acquisition are amortized over the remaining term of the loan as an adjustment to the related loan's yield. The accrual of interest income is discontinued when the collection of a loan or interest, in whole or in part, is doubtful. Allowance for loan and lease losses. For each reporting period, 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. Management's determination of the adequacy of the ALLL is based on an assessment of the probable incurred loan and lease losses inherent in the portfolio given the conditions at the time. 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 through payments from the borrower or the liquidation of collateral. Commercial loan and lease relationships greater than $250,000 that are considered impaired, or designated as a TDR, are evaluated to determine the need for a specific allowance based on the borrower's overall financial condition, resources, payment record, guarantor support and the realizable value of any collateral. The allowance for non-impaired commercial loans and leases, as well as impaired commercial loan and lease relationships less than $250,000 , includes a process of estimating the probable losses incurred in the portfolio by loan type, based on First Financial's internal system of credit risk ratings and historical loss data. These estimates may also be adjusted based upon trends in the values of the underlying collateral, delinquent and nonaccrual loans, prevailing economic conditions and changes in lending strategies, among other influencing factors. Consumer loans are generally evaluated by loan type, as these loans exhibit homogeneous characteristics. The allowance for consumer loans, which includes residential real estate, installment, home equity, credit card loans and overdrafts, is established by estimating probable losses incurred in each particular category of consumer loans. The estimate of losses is primarily based on historical loss rates for each category and may be adjusted for trends in delinquent and nonaccrual loans, prevailing economic conditions and other significant influencing factors. Consumer loans greater than $250,000 classified as TDRs are individually evaluated to determine an appropriate allowance. For purchased impaired loans, expected cash flows are re-estimated periodically with declines in gross expected cash flows recorded as provision expense during the period. Reserve for unfunded commitments . First Financial maintains a reserve that it considers sufficient to absorb probable losses incurred in standby letters of credit and outstanding loan commitments. First Financial determines the adequacy of the reserve based upon an evaluation of the unfunded credit facilities, which includes consideration of historical commitment utilization experience, credit risk ratings and historical loss rates, consistent with the Company's ALLL methodology. The reserve for unfunded commitments is included in Accrued interest and other liabilities on the Consolidated Balance Sheets and adjustments are recorded in Other noninterest expense in the Consolidated Statements of Income. Premises and equipment. Premises and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation and amortization are principally computed on the straight-line method over the estimated useful lives of the assets. Useful lives generally range from 10 to 40 years for building and building improvements; 3 to 10 years for furniture, fixtures and equipment; and 3 to 5 years for software, hardware and data handling equipment. Land improvements are depreciated over 20 years and leasehold improvements are depreciated over the lesser of the term of the respective lease or the useful life of the asset. Premises and equipment are evaluated for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Maintenance and repairs are expensed as incurred. Bank-owned life insurance. First Financial purchases life insurance policies on the lives of certain employees and is the owner and beneficiary of the policies. The Bank invests in these policies to provide an efficient form of funding for long-term retirement and other employee benefits costs. The policies are included within Accrued interest and other assets in the Consolidated Balance Sheets at each policy’s respective cash surrender value with changes recorded in Other noninterest income in the Consolidated Statements of Income. Goodwill. Under accounting for business combinations, the net assets of entities acquired by First Financial are recorded at their estimated fair value at the date of acquisition. The excess cost of the acquisition over the fair value of net assets acquired is recorded as goodwill. Goodwill and intangible assets deemed to have indefinite lives, if any, are not amortized, but are subject to annual impairment tests. The Company is required to evaluate goodwill for impairment on an annual basis or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. First Financial performs its annual impairment test effective October 1, absent events or changes in circumstances that indicate the carrying value of goodwill may not be recoverable. The Company’s goodwill is accounted for in a single reporting unit representing the consolidated entity. Fair value is estimated using the market capitalization of the Company as of the annual impairment testing date. First Financial also utilizes additional information and analyses to corroborate the use of the Company’s market capitalization as a proper indicator of fair value for purposes of the annual goodwill impairment test. Core deposit intangibles. CDI represent the estimated value of acquired customer deposit relationships. CDI are recorded at fair value at the date of acquisition and are based on a discounted cash flow methodology that gives appropriate consideration to expected customer attrition rates, cost of the deposit base, reserve requirements and the net maintenance cost attributable to customer deposits. Core deposit intangibles are recorded in Other intangibles on the Consolidated Balance Sheets and are amortized on an accelerated basis over their estimated useful lives. Other real estate owned. OREO consists of properties acquired by the Company primarily through the loan foreclosure or repossession process, or other resolution activity that results in partial or total satisfaction of problem loans. OREO properties are recorded at fair value, less estimated disposal costs (net realizable value). Losses arising at the time of acquisition of such properties are charged against the ALLL. Management performs periodic valuations to assess the adequacy of recorded OREO balances and subsequent changes in the carrying value of OREO properties are recorded in the Consolidated Statements of Income. Improvements to OREO properties may be capitalized if the improvements contribute to the overall value of the property, but may not be capitalized in excess of the net realizable value of the property. When management disposes of an OREO property, any gains or losses realized at the time of disposal are reflected in the Consolidated Statements of Income. Affordable housing projects. First Financial has investments in certain qualified affordable housing projects. These projects are indirect federal subsidies 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 properties to qualified tenants, resulting in 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. 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. The Company’s recorded investment in these entities is carried in Accrued interest and other assets on the Consolidated Balance Sheets. Income taxes. First Financial and its subsidiaries file a consolidated federal income tax return. Each subsidiary provides for income taxes on a separate return basis, and remits to First Financial amounts determined to be currently payable. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Interest and penalties on income tax assessments or income tax refunds are recognized as a component of noninterest expense in the Consolidated Statements of Income. Pension. First Financial sponsors a non-contributory defined benefit pension plan covering substantially all employees. The measurement of the accrued benefit liability and the annual pension expense involves actuarial and economic assumptions, which include the discount rate, the expected return on plan assets and the rate of compensation increase. Derivative instruments. First Financial accounts for its derivative financial instruments in accordance with FASB ASC Topic 815, Derivatives and Hedging. FASB ASC Topic 815 requires all derivative instruments to be carried at fair value on the balance sheet. The accounting for changes in the fair value of derivatives is based on the intended use of the derivative and the resulting designation. Derivatives used to hedge the exposure to changes in the fair value of an asset, liability or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Derivatives used to hedge the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. 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. Upon entering into an interest rate swap with a borrower, the Bank simultaneously enters into an offsetting swap agreement with an institutional counterparty, with substantially matching terms. These matched interest rate swap agreements generally involve the receipt by First Financial of floating rate amounts from the counterparties in exchange for payments to these counterparties by First Financial of fixed rate amounts received from commercial borrowers over the life of the agreements. First Financial's matched interest rate swaps qualify as derivatives, but are not designated as hedging instruments. The net interest receivable or payable on matched interest rate swaps is accrued and recognized as an adjustment to interest income. The fair values of client derivatives are included within Accrued interest and other assets and Accrued interest and other liabilities in the Consolidated Balance Sheets. 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 fair value of these agreements is recorded in the Consolidated Balance Sheets in Accrued interest and other liabilities. 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 and Loans held for sale. The fair value of these agreements is recorded in the Consolidated Balance Sheets in Accrued interest and other assets. Stock-based compensation. First Financial grants stock-based awards, including restricted stock awards and options to purchase the Company’s common stock. Stock option grants are for a fixed number of shares to employees and directors with an exercise price equal to the fair value of the shares at the date of grant. Stock-based compensation expense is recognized in the Consolidated Statements of Income on a straight-line basis over the vesting period. As compensation expense is recognized, a deferred tax asset is recorded that represents an estimate of the future tax deduction from exercise. At the time stock-based awards are exercised, canceled or expire, First Financial may be required to recognize an adjustment to tax expense. Earnings per share. Basic earnings per common share is computed by dividing net income available to common shareholders by the weighted average number of shares of common stock outstanding during the period. Diluted earnings per common share is computed by dividing net income available to common shareholders by the weighted average number of common shares outstanding, unvested shares and dilutive common stock equivalents outstanding during the period. Common stock equivalents, which consist of common stock issuable under the assumed exercise of stock options granted under First Financial's stock-based compensation plans and the assumed conversion of common stock warrants, are calculated using the treasury stock method. Segments and related information. While the Company monitors the operating results of its six lines of business, operations are managed and financial performance is evaluated on a consolidated basis. Accordingly, and consistent with prior years, all of the Company's operations are considered by management to be aggregated in one reportable operating segment.

RECENTLY ADOPTED AND ISSUED ACC

RECENTLY ADOPTED AND ISSUED ACCOUNTING STANDARDS	12 Months Ended
RECENTLY ADOPTED AND ISSUED ACCOUNTING STANDARDS	Dec. 31, 2018
Accounting Policies [Abstract]
RECENTLY ADOPTED AND ISSUED ACCOUNTING STANDARDS	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 16 – 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, First Financial reclassified $0.2 million of net unrealized gain on AFS equity securities from AOCI to Retained Earnings. Additionally, i n accordance with the guidance, the Company measured the fair value of its financial instruments as of December 31, 2018 using an exit price notion. For further detail, see Note 21 – 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. First Financial plans to record a cumulative effect adjustment effective at the beginning of 2019 which will include approximately $62.5 million of lease assets and $68.1 million of related lease liabilities, but the adoption is not expected to have a material impact to net income. 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 AFS 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. First Financial currently expects to recognize a one-time cumulative effect adjustment to the ALLL as of January 1, 2020. However, in April 2018, the federal banking regulators proposed transitional arrangements to permit banking organizations to phase in the day-one impact of the adoption of this standard on regulatory capital over a three year period. 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, but the ALLL is expected to increase upon adoption since the allowance will be required to cover the full expected life of the portfolio. The extent of this increase is still being evaluated and will depend on economic conditions and the composition of the loan and lease portfolio at the time of adoption. 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 updated its footnote presentation accordingly. This updated did not have a material impact on the Consolidated Financial Statements. For further detail, see Note 15 - Employee Benefit Plans in the Notes to 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 and may reclassify securities from HTM to AFS as a result. 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 from accumulated other comprehensive income to retained earnings. There were no other income tax effects related to the Act that were reclassified as a result of the adoption of this update.

RESTRICTIONS ON CASH AND DIVIDE

RESTRICTIONS ON CASH AND DIVIDENDS	12 Months Ended
RESTRICTIONS ON CASH AND DIVIDENDS	Dec. 31, 2018
Subsidiaries [Member]
Restrictions on Subsidiary Dividends, Loans or Advances [Line Items]
Restrictions On Cash And Dividends [Text Block]	Restrictions on Cash and Dividends First Financial is required by the FRB to hold cash in reserve against deposit liabilities when total reservable deposit liabilities exceed the regulatory exemption known as the reserve requirement. The reserve requirement is calculated based on a two-week average of daily net transaction account deposits as defined by the FRB and may be satisfied with average vault cash during the following two-week maintenance period. When vault cash is not sufficient to meet the reserve requirement, the remaining amount must be satisfied with average funds held at the FRB. First Financial's deposit at the FRB is recorded in Interest-bearing deposits with other banks on the Consolidated Balance Sheets. The average required reserve balances, based upon the average level of First Financial's transaction deposits were $85.9 million and $66.7 million for 2018 and 2017 , respectively. Dividends paid by First Financial to its shareholders are principally funded through dividends paid to the Company by its subsidiaries, however, certain restrictions exist regarding the ability of the Bank to transfer funds to First Financial in the form of cash dividends, loans or advances. The approval of the Federal Reserve Board and the ODFI is required for the Bank to pay dividends in excess of the regulatory limit, which is equal to the net income of the current year through the dividend date combined with the Bank's retained net income from the two preceding years. As of December 31, 2018 , First Financial's subsidiaries had retained earnings of $637.2 million , of which $181.3 million was available for distribution to First Financial without prior regulatory approval.

INVESTMENTS

INVESTMENTS	12 Months Ended
INVESTMENTS	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
INVESTMENTS	Investment Securities The following is a summary of HTM and AFS investment securities as of December 31, 2018 : Held-to-maturity Available-for-sale (Dollars in thousands) Amortized cost Unrecognized gain Unrecognized loss Fair value Amortized cost Unrealized gain Unrealized loss Fair value U.S. Treasuries $ 0 $ 0 $ 0 $ 0 $ 99 $ 0 $ (2 ) $ 97 Securities of U.S. government agencies and corporations 0 0 0 0 32,095 57 (233 ) 31,919 Mortgage-backed securities - residential 25,565 0 (1,045 ) 24,520 565,071 691 (7,163 ) 558,599 Mortgage-backed securities - commercial 147,780 258 (4,385 ) 143,653 423,797 819 (3,581 ) 421,035 Collateralized mortgage obligations 12,540 0 (633 ) 11,907 928,586 4,319 (6,158 ) 926,747 Obligations of state and other political subdivisions 243,443 1,954 (1,359 ) 244,038 257,300 2,554 (1,429 ) 258,425 Asset-backed securities 0 0 0 0 511,430 611 (2,810 ) 509,231 Other securities 0 0 0 0 73,948 358 (1,104 ) 73,202 Total $ 429,328 $ 2,212 $ (7,422 ) $ 424,118 $ 2,792,326 $ 9,409 $ (22,480 ) $ 2,779,255 The following is a summary of HTM and AFS investment securities as of December 31, 2017 : Held-to-maturity Available-for-sale (Dollars in thousands) Amortized Unrecognized 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 During the year ended December 31, 2018 , proceeds on the sale of $290.7 million of AFS securities resulted in gains of $0.5 million and losses of $0.6 million , with insignificant tax expense. During the year ended December 31, 2017 , proceeds on the sale of $190.0 million of AFS securities resulted in gains of $1.8 million and losses of $0.2 million and tax expense of $0.6 million . During the year ended December 31, 2016 , proceeds on the sale of $207.0 million of AFS securities resulted in gains of $1.2 million and losses of $1.0 million and tax expense of $0.1 million . In addition to the sale of certain securities, First Financial reclassified $372.1 million of HTM securities to AFS to align with post-merger investment strategies during the second quarter 2018. The carrying value of investment securities pledged as collateral to secure public deposits, repurchase agreements and for other purposes as required by law totaled $1.2 billion at December 31, 2018 and $0.8 billion at December 31, 2017 . The following table provides a summary of investment securities by contractual maturity as of December 31, 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 Due in one year or less $ 0 $ 0 $ 5,972 $ 5,977 Due after one year through five years 275 279 63,995 64,040 Due after five years through ten years 21,110 21,374 133,360 133,594 Due after ten years 222,058 222,385 160,115 160,032 Mortgage-backed securities - residential 25,565 24,520 565,071 558,599 Mortgage-backed securities - commercial 147,780 143,653 423,797 421,035 Collateralized mortgage obligations 12,540 11,907 928,586 926,747 Asset-backed securities 0 0 511,430 509,231 Total $ 429,328 $ 424,118 $ 2,792,326 $ 2,779,255 Unrealized gains and losses on debt securities are generally due to fluctuations in current market yields relative to the yields of the 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, in addition to 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 December 31, 2018 or 2017 . As of December 31, 2018 , the Company's investment securities portfolio consisted of 1,417 securities, of which 504 securities 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: December 31, 2018 Less than 12 months 12 months or more Total (Dollars in thousands) Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss U.S. Treasuries $ 0 $ 0 $ 97 $ (2 ) $ 97 $ (2 ) Securities of U.S. government agencies and corporations 0 0 16,777 (233 ) 16,777 (233 ) Mortgage-backed securities - residential 186,029 (935 ) 264,795 (7,273 ) 450,824 (8,208 ) Mortgage-backed securities - commercial 147,754 (369 ) 232,363 (7,597 ) 380,117 (7,966 ) Collateralized mortgage obligations 194,795 (1,546 ) 240,514 (5,245 ) 435,309 (6,791 ) Obligations of state and other political subdivisions 62,805 (299 ) 86,644 (2,489 ) 149,449 (2,788 ) Asset-backed securities 336,437 (2,312 ) 37,105 (498 ) 373,542 (2,810 ) Other securities 33,752 (884 ) 4,570 (220 ) 38,322 (1,104 ) Total $ 961,572 $ (6,345 ) $ 882,865 $ (23,557 ) $ 1,844,437 $ (29,902 ) December 31, 2017 Less than 12 months 12 months or more Total (Dollars in thousands) Fair Unrealized Fair Unrealized Fair Unrealized 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 ) For further detail on the fair value of investment securities, see Note 21 – Fair Value Disclosures.

LOANS

LOANS	12 Months Ended
LOANS	Dec. 31, 2018
Loans [Abstract]
LOANS (excluding covered loans)	Loans and Leases First Financial offers clients a variety of commercial and consumer loan and lease products with various 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 accounts. 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 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 of 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 as 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 December 31, 2018 Real Estate (Dollars in thousands) Commercial & industrial Construction Commercial Lease financing Total Pass $ 2,432,834 $ 548,323 $ 3,664,434 $ 90,902 $ 6,736,493 Special Mention 24,594 603 38,653 0 63,850 Substandard 57,233 9 51,594 2,513 111,349 Doubtful 0 0 0 0 0 Total $ 2,514,661 $ 548,935 $ 3,754,681 $ 93,415 $ 6,911,692 Residential real estate Home Equity Installment Credit card Total Performing $ 939,936 $ 811,108 $ 93,038 $ 46,382 $ 1,890,464 Nonperforming 15,710 6,174 174 0 22,058 Total $ 955,646 $ 817,282 $ 93,212 $ 46,382 $ 1,912,522 As of December 31, 2017 Real Estate (Dollars in thousands) Commercial & industrial Construction Commercial Lease 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 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 or any portion thereof remains unpaid after the due date of the scheduled payment. Loan delinquency, including nonaccrual loans, was as follows: As of December 31, 2018 (Dollars in thousands) 30 – 59 days past due 60 – 89 days past due > 90 days past due Total past due Current Subtotal Purchased impaired Total > 90 days past due and still accruing Loans Commercial & industrial $ 13,369 $ 41 $ 7,423 $ 20,833 $ 2,488,450 $ 2,509,283 $ 5,378 $ 2,514,661 $ 0 Lease financing 352 0 0 352 93,063 93,415 0 93,415 0 Construction real estate 0 0 0 0 548,687 548,687 248 548,935 0 Commercial real estate 6,279 1,158 12,644 20,081 3,682,455 3,702,536 52,145 3,754,681 0 Residential real estate 11,060 2,976 4,535 18,571 902,404 920,975 34,671 955,646 0 Home equity 5,245 1,228 2,578 9,051 804,835 813,886 3,396 817,282 0 Installment 420 37 145 602 92,128 92,730 482 93,212 0 Credit card 541 96 63 700 45,682 46,382 0 46,382 63 Total $ 37,266 $ 5,536 $ 27,388 $ 70,190 $ 8,657,704 $ 8,727,894 $ 96,320 $ 8,824,214 $ 63 As of December 31, 2017 (Dollars in thousands) 30 - 59 days past due 60 - 89 days past due > 90 days past due Total past due Current Subtotal Purchased impaired Total > 90 days past due and still accruing 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 to adhere to contractual payment terms by the borrower, 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 none of the principal and interest is due and unpaid, and the Bank expects repayment of the remaining contractual principal and interest. 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 196 TDRs totaling $38.5 million at December 31, 2018 , including $16.1 million of loans on accrual status and $22.4 million of loans classified as nonaccrual. First Financial had no commitments outstanding to lend additional funds to borrowers whose loan terms have been modified through TDRs, and the ALLL included reserves of $1.5 million related to TDRs as of December 31, 2018 . For the years ended December 31, 2018 , 2017 and 2016 , First Financial charged off $0.9 million , $0.3 million and $0.5 million , respectively, for the portion of TDRs determined to be uncollectible. Additionally, as of December 31, 2018 , approximately $7.9 million of the 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 of loans 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. 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. First Financial had 247 TDRs totaling $35.4 million at December 31, 2016 , including $30.2 million of loans on accrual status and $5.1 million of loans classified as nonaccrual. First Financial had $0.9 million of commitments outstanding to lend additional funds to borrowers whose loan terms have been modified through TDRs. At December 31, 2016 , the ALLL included reserves of $1.9 million related to TDRs, and $22.6 million of the accruing TDRs had been performing in accordance with the restructured terms for more than one year. The following table provides information on loan modifications classified as TDRs during the years ended December 31, 2018 , 2017 and 2016 : Years ended December 31, 2018 2017 2016 (Dollars in thousands) Number of loans Pre-modification loan balance Period end balance Number of loans Pre-modification loan balance Period end balance Number of loans Pre-modification loan balance Period end balance Commercial & industrial 17 $ 23,943 $ 23,890 7 $ 5,724 $ 5,661 18 $ 3,402 $ 3,508 Construction real estate 0 0 0 0 0 0 0 0 0 Commercial real estate 8 3,385 3,150 8 1,816 1,758 16 5,200 4,752 Residential real estate 13 1,148 1,073 6 416 315 5 840 787 Home equity 5 95 192 1 39 39 5 165 156 Installment 0 0 0 0 0 0 3 9 9 Total 43 $ 28,571 $ 28,305 22 $ 7,995 $ 7,773 47 $ 9,616 $ 9,212 The following table provides information on how TDRs were modified during the years ended December 31, 2018 , 2017 and 2016 : Years Ended December 31, (Dollars in thousands) 2018 2017 2016 Extended maturities $ 4,093 $ 3,261 $ 2,571 Adjusted interest rates 52 2,767 0 Combination of rate and maturity changes 0 489 3,046 Forbearance 23,175 1,181 88 Other (1) 985 75 3,507 Total $ 28,305 $ 7,773 $ 9,212 (1) Other 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 off 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 twelve months ended December 31, 2018 , there was one TDR with an insignificant balance for which there was a payment default during the period that occurred within twelve months of the loan modification. For the twelve months ended December 31, 2017 and 2016 , there was one TDR and four TDRs, respectively, with balances of $1.5 million and $0.3 million , respectively, for which there was a payment default during the period that occurred within twelve months of the loan modification. 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, as of December 31: (Dollars in thousands) 2018 2017 2016 Impaired loans Nonaccrual loans (1) Commercial & industrial $ 30,925 $ 5,229 $ 2,419 Lease financing 22 82 195 Construction real estate 9 29 0 Commercial real estate 20,500 10,616 6,098 Residential real estate 13,495 4,140 5,251 Home equity 5,580 3,743 3,400 Installment 169 243 367 Total nonaccrual loans 70,700 24,082 17,730 Accruing troubled debt restructurings 16,109 17,545 30,240 Total impaired loans $ 86,809 $ 41,627 $ 47,970 Interest income effect Gross amount of interest that would have been recorded under original terms $ 4,656 $ 3,397 $ 2,848 Interest included in income Nonaccrual loans 715 535 375 Troubled debt restructurings 642 710 876 Total interest included in income 1,357 1,245 1,251 Net impact on interest income $ 3,299 $ 2,152 $ 1,597 Commitments outstanding to borrowers with nonaccrual loans $ 200 $ 0 $ 0 (1) Nonaccrual loans include nonaccrual TDRs of $22.4 million , $6.4 million and $5.1 million as of December 31, 2018 , 2017 and 2016 , respectively. First Financial individually reviews all impaired commercial loan relationships greater than $250,000 , 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, resources, and 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, excluding purchased impaired loans, is as follows: December 31, 2018 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 $ 36,694 $ 42,561 $ 0 $ 7,162 $ 8,460 $ 0 Lease financing 22 22 0 82 82 0 Construction real estate 9 26 0 29 60 0 Commercial real estate 23,513 31,375 0 18,423 20,837 0 Residential real estate 17,297 19,975 0 6,876 8,145 0 Home equity 6,351 7,461 0 4,356 5,399 0 Installment 174 563 0 255 422 0 Total 84,060 101,983 0 37,183 43,405 0 Loans with an allowance recorded Commercial & industrial 939 939 667 169 169 169 Lease financing 0 0 0 0 0 0 Construction real estate 0 0 0 0 0 0 Commercial real estate 1,509 1,509 461 3,119 3,120 448 Residential real estate 301 301 32 1,056 1,063 160 Home equity 0 0 0 100 100 2 Installment 0 0 0 0 0 0 Total 2,749 2,749 1,160 4,444 4,452 779 Total Commercial & industrial 37,633 43,500 667 7,331 8,629 169 Lease financing 22 22 0 82 82 0 Construction real estate 9 26 0 29 60 0 Commercial real estate 25,022 32,884 461 21,542 23,957 448 Residential real estate 17,598 20,276 32 7,932 9,208 160 Home equity 6,351 7,461 0 4,456 5,499 2 Installment 174 563 0 255 422 0 Total $ 86,809 $ 104,732 $ 1,160 $ 41,627 $ 47,857 $ 779 Years ended December 31, 2018 2017 2016 (Dollars in thousands) Average balance Interest Average balance Interest income recognized Average Interest Loans with no related allowance recorded Commercial & industrial $ 14,498 $ 360 $ 13,167 $ 280 $ 13,619 $ 309 Lease financing 21 0 112 4 150 3 Construction real estate 20 2 601 1 0 0 Commercial real estate 24,738 490 20,935 563 14,252 357 Residential real estate 11,359 301 7,616 196 7,752 199 Home equity 5,541 114 4,032 99 4,830 86 Installment 274 2 332 4 366 7 Total 56,451 1,269 46,795 1,147 40,969 961 Loans with an allowance recorded Commercial & industrial 900 44 1,204 28 1,098 37 Lease financing 0 0 0 0 214 8 Construction real estate 0 0 0 0 0 0 Commercial real estate 1,402 18 2,634 40 7,792 211 Residential real estate 895 23 1,112 26 1,374 30 Home equity 80 3 101 4 101 4 Installment 0 0 0 0 0 0 Total 3,277 88 5,051 98 10,579 290 Total Commercial & industrial 15,398 404 14,371 308 14,717 346 Lease financing 21 0 112 4 364 11 Construction real estate 20 2 601 1 0 0 Commercial real estate 26,140 508 23,569 603 22,044 568 Residential real estate 12,254 324 8,728 222 9,126 229 Home equity 5,621 117 4,133 103 4,931 90 Installment 274 2 332 4 366 7 Total $ 59,728 $ 1,357 $ 51,846 $ 1,245 $ 51,548 $ 1,251 OREO. OREO is comprised of properties acquired by the Company primarily through the loan foreclosure or repossession process, or other resolution activities that result in partial or total satisfaction of problem loans. Changes in OREO were as follows: Years ended December 31, (Dollars in thousands) 2018 2017 2016 Balance at beginning of year $ 2,781 $ 6,284 $ 13,254 Additions Commercial 1,269 1,732 1,850 Residential 1,913 2,387 1,022 Total additions 3,182 4,119 2,872 Disposals Commercial (2,967 ) (5,409 ) (6,993 ) Residential (830 ) (1,574 ) (2,363 ) Total disposals (3,797 ) (6,983 ) (9,356 ) Valuation adjustments Commercial (355 ) (439 ) (345 ) Residential (410 ) (200 ) (141 ) Total valuation adjustments (765 ) (639 ) (486 ) Balance at end of year $ 1,401 $ 2,781 $ 6,284

ALLOWANCE FOR LOAN AND LEASE LO

ALLOWANCE FOR LOAN AND LEASE LOSSES	12 Months Ended
ALLOWANCE FOR LOAN AND LEASE LOSSES	Dec. 31, 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. For further discussion of First Financial's allowance methodology, see Note 1 – Summary of Significant Accounting Policies. 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 as of December 31 were as follows: 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 year $ 17,598 $ 675 $ 3,577 $ 20,930 $ 4,683 $ 4,935 $ 307 $ 1,316 $ 54,021 Provision for loan and lease losses 10,615 454 (310 ) 847 492 829 (85 ) 1,744 14,586 Gross charge-offs (11,533 ) 0 0 (4,835 ) (422 ) (1,725 ) (435 ) (1,720 ) (20,670 ) Recoveries 2,066 1 146 4,106 211 1,309 575 191 8,605 Total net charge-offs (9,467 ) 1 146 (729 ) (211 ) (416 ) 140 (1,529 ) (12,065 ) Ending allowance for loan and lease losses $ 18,746 $ 1,130 $ 3,413 $ 21,048 $ 4,964 $ 5,348 $ 362 $ 1,531 $ 56,542 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 year $ 19,225 $ 716 $ 3,282 $ 26,540 $ 3,208 $ 3,043 $ 388 $ 1,559 $ 57,961 Provision for loan and lease losses 6,917 (42 ) 207 (7,291 ) 1,695 1,778 (90 ) 408 3,582 Gross charge-offs (10,194 ) 0 (1 ) (1,038 ) (435 ) (913 ) (225 ) (857 ) (13,663 ) Recoveries 1,650 1 89 2,719 215 1,027 234 206 6,141 Total net charge-offs (8,544 ) 1 88 1,681 (220 ) 114 9 (651 ) (7,522 ) Ending allowance for loan and lease losses $ 17,598 $ 675 $ 3,577 $ 20,930 $ 4,683 $ 4,935 $ 307 $ 1,316 $ 54,021 2016 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 year $ 16,995 $ 821 $ 1,810 $ 23,656 $ 4,014 $ 3,943 $ 386 $ 1,773 $ 53,398 Provision for loan and lease losses 3,705 (106 ) 1,280 5,365 (655 ) (175 ) 53 673 10,140 Gross charge-offs (2,630 ) 0 (93 ) (4,983 ) (387 ) (1,445 ) (386 ) (1,190 ) (11,114 ) Recoveries 1,155 1 285 2,502 236 720 335 303 5,537 Total net charge-offs (1,475 ) 1 192 (2,481 ) (151 ) (725 ) (51 ) (887 ) (5,577 ) Ending allowance for loan and lease losses $ 19,225 $ 716 $ 3,282 $ 26,540 $ 3,208 $ 3,043 $ 388 $ 1,559 $ 57,961 The ALLL balance and the recorded investment in loans by portfolio segment and based on impairment method as of December 31 were as follows: December 31, 2018 Real Estate (Dollars in thousands) Commercial & industrial Lease financing Construction Commercial Residential Home equity Installment Credit card Total Ending allowance on loans individually evaluated for impairment $ 667 $ 0 $ 0 $ 461 $ 32 $ 0 $ 0 $ 0 $ 1,160 Ending allowance on loans collectively evaluated for impairment 18,079 1,130 3,413 20,587 4,932 5,348 362 1,531 55,382 Ending allowance for loan and lease losses $ 18,746 $ 1,130 $ 3,413 $ 21,048 $ 4,964 $ 5,348 $ 362 $ 1,531 $ 56,542 Loans and Leases Ending balance of loans individually evaluated for impairment $ 37,633 $ 22 $ 9 $ 25,022 $ 17,598 $ 6,351 $ 174 $ 0 $ 86,809 Ending balance of loans collectively evaluated for impairment 2,477,028 93,393 548,926 3,729,659 938,048 810,931 93,038 46,382 8,737,405 Total loans $ 2,514,661 $ 93,415 $ 548,935 $ 3,754,681 $ 955,646 $ 817,282 $ 93,212 $ 46,382 $ 8,824,214 December 31, 2017 Real Estate (Dollars in thousands) Commercial & industrial Lease financing Construction Commercial Residential Home equity Installment Credit card Total Ending allowance on loans individually evaluated for impairment $ 169 $ 0 $ 0 $ 448 $ 160 $ 2 $ 0 $ 0 $ 779 Ending allowance on loans 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 and Leases Ending balance of loans individually evaluated for impairment $ 7,331 $ 82 $ 29 $ 21,542 $ 7,932 $ 4,456 $ 255 $ 0 $ 41,627 Ending balance of loans 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

PREMISES AND EQUIPMENT

PREMISES AND EQUIPMENT	12 Months Ended
PREMISES AND EQUIPMENT	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
PREMISES AND EQUIPMENT	Premises and Equipment Premises and equipment at December 31 were as follows: (Dollars in thousands) 2018 2017 Land and land improvements $ 57,701 $ 41,711 Buildings 161,817 104,576 Furniture and fixtures 66,567 55,165 Leasehold improvements 29,086 19,377 Construction in progress 5,731 1,721 320,902 222,550 Less: Accumulated depreciation and amortization 105,250 97,514 Total $ 215,652 $ 125,036 Rental expense recorded under operating leases in 2018 , 2017 and 2016 was $9.1 million , $7.1 million and $7.9 million , respectively. First Financial's future minimum lease payments for operating leases are as follows: (Dollars in thousands) 2019 $ 9,568 2020 9,179 2021 8,284 2022 5,016 2023 4,269 Thereafter 15,496 Total $ 51,812

GOODWILL AND OTHER INTANGIBLE A

GOODWILL AND OTHER INTANGIBLE ASSETS	12 Months Ended
GOODWILL AND OTHER INTANGIBLE ASSETS	Dec. 31, 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 years ended December 31, 2018 , 2017 and 2016 are shown below. (Dollars in thousands) 2018 2017 2016 Balance at beginning of year $ 204,084 $ 204,084 $ 204,084 Goodwill resulting from business combinations 676,167 0 0 Balance at end of year $ 880,251 $ 204,084 $ 204,084 First Financial recorded additions to goodwill resulting from the merger with MSFG in 2018. During 2017 and 2016, no additions to goodwill were recorded. 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 annual impairment test of goodwill as of October 1, 2018 and no impairment was indicated. As of December 31, 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 December 31, 2018 and 2017 , First Financial had $40.8 million and $3.8 million , respectively, of other intangible assets on the Consolidated Balance Sheets which primarily consist of CDI. CDI represents 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. CDI was $37.9 million and $3.3 million as of December 31, 2018 and December 31, 2017 , respectively, and First Financial recorded $41.7 million of additions to CDI in 2018, while no additions were recorded in 2017 or 2016. First Financial's CDI have an estimated weighted average remaining life of 8.9 years as of December 31, 2018 . Amortization expense recognized on intangible assets for 2018 , 2017 and 2016 was $7.7 million , $1.3 million and $1.6 million , respectively. The estimated amortization expense of intangible assets for the next five years is as follows: (Dollars in thousands) 2019 $ 8,800 2020 7,010 2021 5,602 2022 3,417 2023 3,155

DEPOSITS

DEPOSITS	12 Months Ended
DEPOSITS	Dec. 31, 2018
Deposits [Abstract]
Deposit Liabilities Disclosures [Text Block]	Deposits Time deposits that meet or exceed the FDIC insurance limit of $250,000 at December 31, 2018 and 2017 were $284.9 million and $174.8 million , respectively. Scheduled maturities of time deposits for the next five years were as follows: (Dollars in thousands) 2019 $ 1,407,996 2020 471,183 2021 163,575 2022 110,170 2023 20,112 Thereafter 528 Total $ 2,173,564

BORROWINGS

BORROWINGS	12 Months Ended
BORROWINGS	Dec. 31, 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. The following shows the remaining contractual maturity of repurchase agreements by collateral pledged: (Dollars in thousands) Overnight and Continuous Repurchase agreements Mortgage-backed securities $ 22,369 Collateralized mortgage obligations 62,222 Total $ 84,591 Securities sold under agreements to repurchase are secured by securities with a carrying amount of $85.5 million and $72.8 million , as of December 31, 2018 and 2017 , respectively. First Financial has a $30.0 million short-term credit facility with an unaffiliated bank that matures in September, 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 December 31, 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 December 31, 2018 and December 31, 2017 . The following is a summary of short-term borrowings for the last three years: 2018 2017 2016 (Dollars in thousands) Amount Rate Amount Rate Amount Rate At December 31, Federal funds purchased and securities sold under agreements to repurchase $ 183,591 1.65 % $ 72,265 0.19 % $ 120,212 0.12 % FHLB borrowings 857,100 2.48 % 742,300 1.43 % 687,700 0.66 % Total $ 1,040,691 2.33 % $ 814,565 1.32 % $ 807,912 0.58 % Average for the year Federal funds purchased and securities sold under agreements to repurchase $ 87,221 0.58 % $ 69,766 0.19 % $ 89,157 0.05 % FHLB borrowings 857,028 2.03 % 760,558 1.05 % 791,259 0.55 % Other short-term borrowings 3,178 4.36 % 41 4.07 % 41 3.56 % Total $ 947,427 1.90 % $ 830,365 0.98 % $ 880,457 0.50 % Maximum month-end balances Federal funds purchased and securities sold under agreements to repurchase $ 183,591 $ 130,633 $ 122,242 FHLB borrowings 1,170,800 957,700 1,035,000 Other short-term borrowings 10,000 0 0 In 2015, First Financial issued $120.0 million of subordinated notes, which have a fixed interest rate of 5.13% payable semiannually and mature in August 2025. These notes are not redeemable by the Company or callable by the holders of the notes prior to maturity. 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 7.40% 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. The subordinated notes are treated as Tier 2 capital for regulatory capital purposes and are included in Long-term debt on the Consolidated Balance Sheets. In addition to subordinated notes, long-term debt also includes FHLB long-term advances. These instruments are primarily utilized to reduce overnight liquidity risk and to mitigate interest rate sensitivity on the Consolidated Balance Sheets. FHLB advances, both short-term and long-term, must be collateralized with qualifying assets, typically certain commercial and residential real estate loans, as well as certain government and agency securities. For ease of borrowing execution, First Financial utilizes a blanket collateral agreement with the FHLB, and at December 31, 2018 , had collateral pledged with a book value of $5.7 billion . The following is a summary of First Financial's long-term debt: 2018 2017 (Dollars in thousands) Amount Average Rate Amount Average Rate Subordinated debt $ 170,550 5.28 % $ 120,000 5.13 % Unamortized debt issuance costs (1,185 ) n/a (1,362 ) n/a FHLB 400,599 2.08 % 241 1.09 % Capital loan with municipality 775 0.00 % 775 0.00 % Total long-term debt $ 570,739 3.04 % $ 119,654 5.14 % As of December 31, 2018 , First Financial's long-term debt matures as follows: (Dollars in thousands) 2019 $ 157,914 2020 104,274 2021 19,007 2022 49,404 2023 0 Thereafter 240,140 Total $ 570,739

DERIVATIVES

DERIVATIVES	12 Months Ended
DERIVATIVES	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVES	Derivatives First Financial uses certain derivative instruments, including 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. For discussion of First Financial's accounting for derivative instruments, see Note 1 – Summary of Significant Accounting Policies. First Financial primarily utilizes interest rate swaps as a means to offer borrowers credit-based products that meet their needs and 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 as 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 this 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 location and amounts recognized in the Consolidated Balance Sheets for client derivatives: December 31, 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 Matched interest rate swaps with borrower Accrued interest and other assets and other liabilities $ 1,359,990 $ 17,402 $ (11,787 ) $ 837,040 $ 7,153 $ (5,529 ) Matched interest rate swaps with counterparty Accrued interest and other liabilities 1,359,990 11,787 (17,401 ) 837,040 5,529 (7,158 ) Total $ 2,719,980 $ 29,189 $ (29,188 ) $ 1,674,080 $ 12,682 $ (12,687 ) At December 31, 2018 , the Company had a total counterparty notional amount outstanding of $1.4 billion , spread among thirteen counterparties, with an outstanding liability from these contracts of $4.9 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. 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 are 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: December 31, 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 $ 29,189 $ (14,577 ) $ 14,612 $ 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 December 31, 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 $ 1,359,990 6.2 $ 5,615 4.70 % 4.67 % Pay fixed, matched interest rate swaps with counterparty 1,359,990 6.2 (5,614 ) 4.67 % 4.70 % Total client derivatives $ 2,719,980 6.2 $ 1 4.68 % 4.68 % 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 $138.4 million as of December 31, 2018 and $95.9 million as of December 31, 2017 . The fair value of these agreements were recorded in Accrued interest and other liabilities on the Consolidated Balance Sheets was $0.1 million at both December 31, 2018 and 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 and loans held for sale. At December 31, 2018 , the notional amount of the IRLCs was $20.8 million and the notional amount of forward commitments was $12.3 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 recorded on the Consolidated Balance Sheets in Accrued interest and other assets and was insignificant at December 31, 2018 and $0.1 million at December 31, 2017 .

RELATED PARTIES TRANSACTIONS

RELATED PARTIES TRANSACTIONS	12 Months Ended
RELATED PARTIES TRANSACTIONS	Dec. 31, 2018
Related Party Transactions [Abstract]
Loans to Related Parties	Related Party Transactions Loans to directors, executive officers, principal holders of First Financial’s common stock and certain related persons were as follows: (Dollars in thousands) 2018 Beginning balance $ 9,873 Additions 2,108 Deductions (9,249 ) Ending balance $ 2,732 Loans 90 days or more past due $ 0 Related parties of First Financial, as defined for inclusion in the table above, were clients of, and had transactions with, subsidiaries of First Financial during the periods noted. Similar transactions with related parties may be expected in future periods.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
COMMITMENTS AND CONTINGENCIES	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	Commitments and Contingencies First Financial offers a variety of financial instruments including 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 losses incurred in letters of credit and outstanding loan commitments and records the reserve within Accrued interest and other liabilities on the Consolidated Balance Sheets. 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 December 31, 2018 and 2017 , respectively. Loan commitments. Loan commitments are agreements to extend credit to a client absent any violation of any condition 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 $3.0 billion and $2.1 billion at December 31, 2018 and 2017 , respectively. As of December 31, 2018 , loan commitments with a fixed interest rate totaled $174.0 million while commitments with variable interest rates totaled $2.9 billion . The fixed rate loan commitments have interest rates ranging from 0.00% to 21.00% for both December 31, 2018 and 2017 . The fixed rate loan commitments have maturities ranging from 1 to 30 years for December 31, 2018 and 1 and 29 years for December 31, 2017 . 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 has issued letters of credit aggregating $32.7 million and $25.3 million at December 31, 2018 , and 2017 , respectively. Management conducts regular reviews of these instruments on an individual client basis. Investments in affordable housing projects. 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 $39.4 million and $35.9 million as of December 31, 2018 and 2017 , respectively. The Company recognized tax credits of $4.9 million and $3.2 million related to its investments in affordable housing projects for the years ended December 31, 2018 and 2017 , respectively. The Company recognized amortization expense which was included in income tax expense of $5.7 million and $4.2 million for the years ended December 31, 2018 and 2017 , respectively. First Financial had no affordable housing contingent commitments as of December 31, 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 included in Accrued interest and other assets on the Consolidated Balance Sheets. The Company’s recorded investment in these entities was approximately $3.9 million at December 31, 2018 , and $3.0 million at December 31, 2017 . The maximum exposure to loss related to these investments was $3.9 million at December 31, 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 $0.5 million and $13.7 million of tax credits for the years ended December 31, 2018 and 2017 , respectively. Recognition of a single historic tax credit investment resulted in a $12.5 million reduction in income tax expense and $11.3 million of other noninterest expenses during 2017. Contingencies/Litigation. First Financial and its subsidiaries are engaged in various matters of litigation from time to time, and have a number of unresolved claims pending. 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 is incidental to our regular business activities. While the ultimate liability with respect to these 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 December 31, 2018 . 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. First Financial had no reserves related to litigation matters as of December 31, 2018 or December 31, 2017 .

INCOME TAXES

INCOME TAXES	12 Months Ended
INCOME TAXES	Dec. 31, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	Income Taxes Income tax expense consisted of the following components: (Dollars in thousands) 2018 2017 2016 Current expense Federal $ 34,330 $ 22,599 $ 40,537 State 1,029 1,265 1,322 Total current expense 35,359 23,864 41,859 Deferred expense (benefit) Federal 4,675 (4,657 ) 528 State 1,592 169 (182 ) Total deferred expense (benefit) 6,267 (4,488 ) 346 Income tax expense $ 41,626 $ 19,376 $ 42,205 The difference between the federal income tax rates applied to income before income taxes, and the effective rates were due to the following: (Dollars in thousands) 2018 2017 2016 Income taxes computed at federal statutory rate on income before income taxes (21% in 2018; 35% in 2017 and 2016) $ 44,986 $ 40,657 $ 45,756 Benefit from tax-exempt income (4,499 ) (3,427 ) (2,911 ) Tax credits (5,439 ) (16,806 ) (2,691 ) Tax rate reduction impact 0 (8,191 ) 0 Basis reduction on historic tax credit 0 4,599 0 Tax benefit of equity compensation (565 ) (1,449 ) (72 ) State income taxes, net of federal tax benefit 2,070 932 741 Affordable housing investments 4,725 2,798 1,923 Other 348 263 (541 ) Income tax expense $ 41,626 $ 19,376 $ 42,205 On December 22, 2017, the Tax Cuts and Jobs Act was signed into law. As a result, First Financial revalued its deferred tax assets and liabilities as well as its investments in affordable housing projects utilizing a 21% federal rate compared to a 35% rate in prior periods. The major components of the temporary differences that gave rise to deferred tax assets and liabilities at December 31, 2018 , and 2017 , were as follows: (Dollars in thousands) 2018 2017 Deferred tax assets Allowance for loan and lease losses $ 12,782 $ 12,134 Fair value adjustments on business combinations 11,199 369 Deferred compensation 392 384 Postretirement benefits other than pension liability 676 564 Accrued stock-based compensation 1,145 932 OREO write-downs 118 97 Interest on nonaccrual loans 1,160 616 Accrued expenses 5,808 3,051 Net unrealized losses on investment securities and derivatives 3,221 249 State net operating loss 3,119 0 Federal tax credit carryforwards 873 0 Other 425 339 Total deferred tax assets 40,918 18,735 Deferred tax liabilities Tax depreciation in excess of book depreciation (9,530 ) (2,510 ) FHLB and FRB stock (4,044 ) (3,384 ) Mortgage-servicing rights (2,285 ) (343 ) Leasing activities (3,881 ) (2,792 ) Retirement obligation (6,614 ) (8,888 ) Intangible assets (12,310 ) (11,559 ) Deferred loan fees and costs (131 ) (371 ) Prepaid expenses (582 ) (210 ) Limited partnership investments (2,367 ) (1,230 ) Other (1,867 ) (2,415 ) Total deferred tax liabilities (43,611 ) (33,702 ) Total net deferred tax liability $ (2,693 ) $ (14,967 ) In conjunction with the MSFG merger, First Financial acquired $3.9 million of state net operating losses, which begin to expire in 2022. The Company expects to fully utilize these net operating losses and, therefore, a valuation allowance is not required at December 31, 2018. The Company also acquired $0.9 million of federal alternative minimum tax credit carryforwards in its merger with MSFG, which are expected to be fully utilized in 2019. The acquired MSFG state net operating loss and federal tax credits are subject to IRC Section 382 and are limited annually. The realization of the Company’s deferred tax assets is dependent upon the Company’s ability to generate taxable income in future periods, the reversal of deferred tax liabilities during the same period and the ability to carry back any losses. The Company has evaluated the available evidence supporting the realization of its deferred tax assets and determined it is more likely than not that the assets will be realized and thus no valuation allowance was recorded at December 31, 2018 and 2017 . With the acquisition of Mainsource in 2018, the Bank’s retained earnings at December 31, 2018 included base-year bad debt reserves, created for tax purposes prior to 1988, of $16.1 million . Base-year reserves are subject to recapture in the event the Bank redeems its stock, makes distributions in excess of current and accumulated earnings and profits (as calculated for federal income tax purposes), loses its “bank” status or liquidates. The Bank has no intention of meeting any of the criteria for recapture. Accordingly, a deferred income tax liability of $3.4 million has not be recorded. At both December 31, 2018 and 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. A progression of unrecognized tax benefits as of December 31, 2018 and 2017 is as follows: (Dollars in thousands) 2018 2017 Balance at beginning of year $ 3,735 $ 3,735 Additions for tax positions of prior years 0 0 Balance at end of year $ 3,735 $ 3,735 The unrecognized tax benefits relate to state income tax exposures where First Financial believes it is likely that, upon examination, a state may take a position contrary to the position taken by the Company. 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 December 31, 2018 and 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 2015 have been closed and are no longer subject to U.S. federal income tax examinations. Tax years 2015 through 2017 remain open to examination by the federal taxing authority. First Financial is no longer subject to state and local income tax examinations for years prior to 2011. Tax years 2011 through 2017 remain open to state and local examination by various other jurisdictions.

EMPLOYEE BENEFIT PLANS

EMPLOYEE BENEFIT PLANS	12 Months Ended
EMPLOYEE BENEFIT PLANS	Dec. 31, 2018
Retirement Benefits [Abstract]
EMPLOYEE BENEFIT PLANS	Employee Benefit Plans Pension plan. 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 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. The investment objective of the Plan is to structure the assets to mirror the liabilities of the Plan, with the fixed income component matching the identified near and long-term plan distributions and the equity component generating growth of capital to meet other future Plan liabilities. The determination of the overall expected long-term return on plan assets was based on the composition of plan assets and a consensus of estimates from similarly managed portfolios of expected future returns. As a result of the plan’s updated actuarial projections for 2018 , First Financial recorded expense related to its pension plan of $0.9 million for 2018 . During 2017 and 2016 , First Financial recorded income of $0.6 million and $1.2 million , respectively. First Financial made no cash contributions to the pension plan in 2018 , 2017 or 2016 and does not expect to make any contributions in 2019. The following tables set forth information concerning amounts recognized in First Financial's Consolidated Balance Sheets and Consolidated Statements of Income related to the Company's pension plan: December 31, (Dollars in thousands) 2018 2017 Change in benefit obligation Benefit obligation at beginning of year $ 71,154 $ 62,729 Service cost 6,501 4,894 Interest cost 2,394 2,325 Actuarial (gain) loss (4,032 ) 6,107 Benefits paid, excluding settlement (7,731 ) (4,901 ) Benefit obligation at end of year 68,286 71,154 Change in plan assets Fair value of plan assets at beginning of year 144,349 131,011 Actual return on plan assets (6,540 ) 18,239 Benefits paid, excluding settlement (7,731 ) (4,901 ) Fair value of plan assets at end of year 130,078 144,349 Amounts recognized in the Consolidated Balance Sheets Assets 61,792 73,195 Liabilities 0 0 Net amount recognized $ 61,792 $ 73,195 Amounts recognized in accumulated other comprehensive income (loss) Net actuarial loss $ 43,711 $ 33,580 Net prior service cost (1,508 ) (1,921 ) Deferred tax assets (9,613 ) (12,028 ) Net amount recognized $ 32,590 $ 19,631 Change in accumulated other comprehensive income (loss) $ 12,959 $ (3,172 ) Accumulated benefit obligation $ 66,320 $ 69,678 Components of net periodic benefit cost December 31, (Dollars in thousands) 2018 2017 2016 Service cost $ 6,501 $ 4,894 $ 5,034 Interest cost 2,394 2,325 2,262 Expected return on assets (9,811 ) (9,358 ) (9,644 ) Amortization of prior service cost (413 ) (413 ) (413 ) Recognized net actuarial loss 2,188 1,924 1,608 Net periodic benefit (income) cost 859 (628 ) (1,153 ) Other changes recognized in accumulated other comprehensive income (loss) Net actuarial (gain) loss 12,319 (2,775 ) (884 ) Prior service cost 0 0 0 Amortization of prior service cost 413 413 413 Amortization of gain (2,188 ) (1,924 ) (1,608 ) Total recognized in accumulated other comprehensive income (loss) 10,544 (4,286 ) (2,079 ) Total recognized in net periodic benefit cost and accumulated other comprehensive income (loss) $ 11,403 $ (4,914 ) $ (3,232 ) Amount expected to be recognized in net periodic pension expense in the coming year Amortization of (gain) loss $ 1,867 $ 2,090 $ 1,754 Amortization of prior service credit (413 ) (413 ) (413 ) Pension plan assumptions December 31, 2018 2017 2016 Benefit obligations Discount rate 4.31 % 3.43 % 3.88 % Rate of compensation increase 3.50 % 3.50 % 3.50 % Net periodic benefit cost Discount rate 3.43 % 3.88 % 4.05 % Expected return on plan assets 7.25 % 7.25 % 7.50 % Rate of compensation increase 3.50 % 3.50 % 3.50 % The fair value of the plan assets as of December 31, 2018 by asset category is shown in the table that follows: Fair Value Measurements (Dollars in thousands) Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Asset Category Cash $ 216 $ 216 $ 0 $ 0 U. S. Government agencies 8,053 0 8,053 0 Fixed income mutual funds 74,453 74,453 0 0 Equity mutual funds 47,356 47,356 0 0 Total $ 130,078 $ 122,025 $ 8,053 $ 0 The fair value of the plan assets as of December 31, 2017 by asset category is shown in the table that follows: Fair Value Measurements (Dollars in thousands) Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Asset Category Cash $ 175 $ 175 $ 0 $ 0 U. S. Government agencies 6,853 0 6,853 0 Fixed income mutual funds 69,154 69,154 0 0 Equity mutual funds 68,167 68,167 0 0 Total $ 144,349 $ 137,496 $ 6,853 $ 0 The level within the fair value hierarchy is based on the lowest level of input that is significant in the fair value measurement. See Note 21 – Fair Value Disclosures for further information related to the framework for measuring fair value and the fair value hierarchy. The following benefit payments, which reflect expected future service, are expected to be paid: (Dollars in thousands) 2019 $ 4,396 2020 5,280 2021 5,229 2022 4,739 2023 4,917 Thereafter 29,948 401(k) plan. First Financial sponsors a defined contribution 401(k) plan which covers substantially all employees. Employees may contribute up to 50.0% of their earnings into the plan, not to exceed applicable limitations prescribed by the Internal Revenue Service. First Financial's contributions to the 401(k) plan are discretionary and vest immediately. First Financial measures the Company's performance compared to its identified peer group in determining whether to recommend a Company contribution, with the amount of the recommended contribution not to exceed 3% of the employee's annual earnings. First Financial recorded no expense related to the Company's contributions to the 401(k) plan during the year ended December 31, 2018 . First Financial recorded $1.9 million and $0.8 million of expense related to the Company's contributions to the 401(k) plan during 2017 and 2016 , respectively.

REVENUE RECOGNITION REVENUE REC

REVENUE RECOGNITION REVENUE RECOGNITION (Notes)	12 Months Ended
REVENUE RECOGNITION REVENUE RECOGNITION (Notes)	Dec. 31, 2018
Revenue Recognition and Deferred Revenue [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, trust and wealth management fees, bankcard income, gain/loss on the sale of OREO and investment brokerage fees. 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 2018 was $31.3 million , which was partially offset by $11.0 million of expenses within Noninterest income. 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.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	12 Months Ended
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	Dec. 31, 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 accumulated other comprehensive income (loss) are as follows: December 31, 2018 Total other comprehensive income (loss) Total accumulated (Dollars in thousands) Prior to Reclass Pre-tax Tax effect Net of tax Beginning balance Net activity Cumulative effect of new standard Ending balance Unrealized gain (loss) on debt securities $ (14,461 ) $ (161 ) $ (14,300 ) $ 3,071 $ (11,229 ) $ (182 ) $ (11,229 ) $ (190 ) $ (11,601 ) Unrealized gain (loss) on derivatives 628 0 628 (144 ) 484 (577 ) 484 (124 ) (217 ) Retirement obligation (12,319 ) (1,775 ) (10,544 ) 2,364 (8,180 ) (19,631 ) (8,180 ) (4,779 ) (32,590 ) Total $ (26,152 ) $ (1,936 ) $ (24,216 ) $ 5,291 $ (18,925 ) $ (20,390 ) $ (18,925 ) $ (5,093 ) $ (44,408 ) December 31, 2017 Total other comprehensive income (loss) Total accumulated other (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 $ 8,447 $ 1,649 $ 6,798 $ (2,431 ) $ 4,367 $ (4,549 ) $ 4,367 $ (182 ) Unrealized gain (loss) on derivatives 810 0 810 (296 ) 514 (1,091 ) 514 (577 ) Retirement obligation 2,775 (1,511 ) 4,286 (1,114 ) 3,172 (22,803 ) 3,172 (19,631 ) Total $ 12,032 $ 138 $ 11,894 $ (3,841 ) $ 8,053 $ (28,443 ) $ 8,053 $ (20,390 ) December 31, 2016 Total other comprehensive income (loss) 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 $ 751 $ 234 $ 517 $ (133 ) $ 384 $ (4,933 ) $ 384 $ (4,549 ) Unrealized gain (loss) on derivatives 809 0 809 (301 ) 508 (1,599 ) 508 (1,091 ) Retirement obligation 884 (1,195 ) 2,079 (834 ) 1,245 (24,048 ) 1,245 (22,803 ) Total $ 2,444 $ (961 ) $ 3,405 $ (1,268 ) $ 2,137 $ (30,580 ) $ 2,137 $ (28,443 ) The following table details the activity reclassified from accumulated other comprehensive income into income during the period: Amount Reclassified from Accumulated Other Comprehensive Income (1) December 31, (Dollars in thousands) 2018 2017 2016 Affected Line Item in the Consolidated Statements of Income Realized gains and losses on securities available-for-sale $ (161 ) $ 1,649 $ 234 Net gain (loss) on sales of investment securities Defined benefit pension plan Amortization of prior service cost (2) 413 413 413 Other noninterest expense Recognized net actuarial loss (2) (2,188 ) (1,924 ) (1,608 ) Other noninterest expense Amortization and settlement charges of defined benefit pension items (1,775 ) (1,511 ) (1,195 ) Total reclassifications for the period, before tax $ (1,936 ) $ 138 $ (961 ) (1) Negative amounts are debits to profit/loss. (2) Included in the computation of net periodic pension cost (see Note 15 - Employee Benefit Plans for additional details).

CAPITAL

CAPITAL	12 Months Ended
CAPITAL	Dec. 31, 2018
Banking and Thrift [Abstract]
CAPITAL	Capital Risk-based capital. First Financial and its subsidiary, First Financial Bank, are subject to regulatory capital requirements administered by federal banking agencies. Capital adequacy guidelines and, additionally for banks, prompt corrective action regulations involve quantitative measures of assets, liabilities and certain off-balance sheet items calculated under regulatory accounting practices. Capital amounts and classifications are also subject to qualitative judgments by regulators. Failure to meet minimum capital requirements can initiate regulatory action. The Board of Governors of the Federal Reserve System approved Basel III in order to strengthen the regulatory capital framework for all banking organizations, subject to a phase-in period for certain provisions. Basel III established and defined quantitative measures to ensure capital adequacy. These measures require First Financial to maintain minimum amounts and ratios of Common Equity tier 1 capital, total and tier 1 capital to risk-weighted assets and tier 1 capital to average assets (leverage ratio). Basel III includes a minimum ratio of common equity tier 1 capital to risk-weighted assets of 6.375% at December 31, 2018, which includes a capital conservation buffer that began on January 1, 2016 at 0.625% and is phased in over a four-year period, increasing by the same amount each subsequent January 1, until fully phased-in at 2.5% of risk-weighted assets on January 1, 2019. Further, the minimum ratio of tier 1 capital to risk-weighted assets increased to 7.875% at December 31, 2018 and all banks are subject to a 4.0% minimum leverage ratio. The required total risk-based capital ratio is unchanged. Failure to maintain the required common equity Tier 1 capital conservation buffer will result in potential restrictions on a bank’s ability to pay dividends, repurchase stock and pay discretionary compensation to its employees. The capital requirements also provide strict eligibility criteria for regulatory capital instruments and change the method for calculating risk-weighted assets in an effort to better identify riskier assets, such as highly volatile commercial real estate and nonaccrual loans. As of December 31, 2018 , management believes the Company and the Bank meet all capital adequacy requirements to which they are subject. The following tables present the actual and required capital amounts and ratios as of December 31, 2018 and 2017 under the Basel III Capital Rules. The minimum required capital amounts presented include the minimum required capital levels based on the current phase-in provisions of the Basel III Capital Rules as well as the minimum required capital levels as of January 1, 2019 when the Basel III Capital Rules have been fully phased-in. Capital levels required to be considered "well capitalized" are based upon prompt corrective action regulations, as amended to reflect the changes under the Basel III Capital Rules. All of First Financial's regulatory capital ratios exceeded the amounts necessary to be classified as “well capitalized,” and total regulatory capital exceeded the “minimum” requirement by $432.8 million on a consolidated basis at December 31, 2018 . Actual Minimum capital Required to be Minimum capital (Dollars in thousands) Capital Ratio Capital Ratio Capital Ratio Capital Ratio December 31, 2018 Common equity tier 1 capital to risk-weighted assets Consolidated $ 1,215,613 11.87 % $ 652,874 6.375 % N/A N/A $ 716,881 7.00 % First Financial Bank 1,279,492 12.50 % 652,590 6.375 % $ 665,386 6.50 % 716,570 7.00 % Tier 1 capital to risk-weighted assets Consolidated 1,257,366 12.28 % 806,491 7.875 % N/A N/A 870,499 8.50 % First Financial Bank 1,279,596 12.50 % 806,141 7.875 % $ 818,937 8.00 % 870,120 8.50 % Total capital to risk-weighted assets Consolidated 1,444,146 14.10 % 1,011,314 9.875 % N/A N/A 1,075,322 10.50 % First Financial Bank 1,344,388 13.13 % 1,010,875 9.875 % 1,023,671 10.00 % 1,074,855 10.50 % Leverage Consolidated 1,257,366 9.71 % 517,958 4.00 % N/A N/A 517,958 4.00 % First Financial Bank 1,279,596 9.89 % 517,710 4.00 % 647,138 5.00 % 517,710 4.00 % Actual Minimum capital Required to be Minimum capital (Dollars in thousands) Capital Ratio Capital Ratio Capital Ratio Capital Ratio December 31, 2017 Common equity tier 1 capital to risk-weighted assets Consolidated $ 755,735 10.63 % $ 408,746 5.75 % N/A N/A $ 497,604 7.00 % First Financial Bank 794,251 11.21 % 407,220 5.75 % $ 460,336 6.50 % 495,746 7.00 % Tier 1 capital to risk-weighted assets Consolidated 755,839 10.63 % 515,376 7.25 % N/A N/A 604,233 8.50 % First Financial Bank 794,355 11.22 % 513,452 7.25 % 566,567 8.00 % 601,978 8.50 % Total capital to risk-weighted assets Consolidated 929,148 13.07 % 657,548 9.25 % N/A N/A 746,406 10.50 % First Financial Bank 856,363 12.09 % 655,093 9.25 % 708,209 10.00 % 743,619 10.50 % Leverage Consolidated 755,839 8.84 % 342,198 4.00 % N/A N/A 342,198 4.00 % First Financial Bank 794,355 9.29 % 342,113 4.00 % 427,642 5.00 % 342,113 4.00 % Share repurchases. In October 2012, First Financial's board of directors approved a share repurchase plan under which the Company has the ability to repurchase up to 5,000,000 common shares. The Company did not repurchase any shares under this plan during 2016, 2017 or 2018. At December 31, 2018 , 3,509,133 common shares remained available for purchase under this repurchase plan. ATM Offering. In March 2017, First Financial initiated an "at-the-market" equity offering program to provide flexibility with respect to capital planning and to support future growth. First Financial was not active through the ATM program during the period.

STOCK OPTIONS AND AWARDS

STOCK OPTIONS AND AWARDS	12 Months Ended
STOCK OPTIONS AND AWARDS	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK OPTIONS AND AWARDS	Stock Options and Awards First Financial follows the provisions of FASB ASC Topic 718, Compensation-Stock Compensation, which requires measurement of compensation cost for all stock-based awards at fair value on the date of grant and recognition of compensation expense over the service period for all awards expected to vest. First Financial recorded share-based compensation expense of $6.2 million for the year ended December 31, 2018 and $5.4 million for the years ended December 31, 2017 and December 31, 2016, within salaries and employee benefits expense related to stock options and restricted stock awards. Total unrecognized compensation cost related to non-vested share-based compensation was $6.9 million at December 31, 2018 and is expected to be recognized over a weighted average period of 1.94 years . As of December 31, 2018 , First Financial had a single active stock-based compensation plan, the Amended and Restated 2012 Stock Plan, under which additional awards may be granted. In May 2012, shareholders approved the First Financial Bancorp. 2012 Stock Plan. In May 2017, the shareholders amended and restated the 2012 Stock Plan as the First Financial Bancorp. Amended and Restated 2012 Stock Plan. At December 31, 2018 , there were 1,877,079 shares available for issuance under the Amended and Restated 2012 Stock Plan. In April 2018, in conjunction with the MSFG merger, First Financial assumed the existing MSFG options which were converted into 83,551 options to purchase First Financial common stock. The converted MSFG options remain subject to all of the terms and conditions of the plan and grant agreements under which the MSFG Stock Options were originally issued. The assumed options were exercisable at the time of the merger and remain outstanding for 10 years after the initial grant date with all options expiring at the end of the exercise period. At December 31, 2018, 62,410 options were outstanding under the Plan, all of which expire on or before February 3, 2024 . First Financial utilizes the Black-Scholes valuation model to determine the fair value of stock options granted. In addition to the stock option strike price, the Black-Scholes valuation model incorporates the following assumptions: the expected dividend yield based on historical dividend payouts; the expected stock price volatility based on the historical volatility of Company stock for a period approximating the expected life of the options; the risk-free rate based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option; and the expected option life represented by the period of time the options are expected to be outstanding, and is based on historical trends. No options were granted in 2018 , 2017 or 2016 . Stock option activity for the year ended December 31, 2018 , is summarized as follows: (Dollars in thousands, except share and per share data) Number of shares Weighted average exercise price Weighted average remaining contractual life Aggregate intrinsic value Outstanding at beginning of year 11,800 $ 11.64 Granted 0 0.00 Assumed 83,551 8.54 Exercised (32,941 ) 8.62 Forfeited or expired 0 0.00 Outstanding at end of year 62,410 $ 9.08 3.72 $ 914 Exercisable at end of year 62,410 $ 9.08 3.72 $ 914 The intrinsic value of stock options is defined as the difference between the current market value and the exercise price. First Financial uses treasury shares purchased under the Company's share repurchase program to satisfy share-based exercises. 2018 2017 2016 Total intrinsic value of options exercised $ 734 $ 1,533 $ 661 Cash received from exercises $ 284 $ 341 $ 801 Tax benefit from exercises $ 1,439 $ 1,991 $ 1,958 Restricted stock awards are recorded at fair value as of the grant date as a component of shareholders' equity and amortized on a straight-line basis to salaries and benefits expense over the specified vesting periods, which is currently three years for employees and one year for non-employee directors. The vesting of these awards for employees and non-employee directors may require a service period to be met, and certain awards may also require performance measures to be met. Activity in restricted stock for the previous three years ended December 31 is summarized as follows: 2018 2017 2016 Number of shares Weighted average grant date fair value Number of shares Weighted average grant date fair value Number of shares Weighted average grant date fair value Nonvested at beginning of year 468,372 $ 21.63 648,817 $ 17.82 643,641 $ 17.21 Granted 303,930 28.94 234,529 27.36 317,695 18.13 Vested (267,031 ) 20.94 (307,825 ) 18.12 (263,713 ) 16.82 Forfeited (42,825 ) 26.38 (107,149 ) 21.18 (48,806 ) 17.37 Nonvested at end of year 462,446 $ 26.39 468,372 $ 21.63 648,817 $ 17.82 The fair value of restricted stock is determined based on the number of shares granted and the quoted price of First Financial's common stock. The fair value of restricted stock vested during 2018 , 2017 and 2016 was $5.6 million , $5.6 million and $4.4 million , respectively.

EARNINGS PER COMMON SHARE

EARNINGS PER COMMON SHARE	12 Months Ended
EARNINGS PER COMMON SHARE	Dec. 31, 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: (Dollars in thousands, except share and per share data) 2018 2017 2016 Numerator Net income $ 172,595 $ 96,787 $ 88,526 Denominator Basic earnings per common share - weighted average shares 88,582,090 61,529,460 61,206,093 Effect of dilutive securities Employee stock awards 514,680 581,329 729,335 Warrants 517,435 60,801 49,994 Diluted earnings per common share - adjusted weighted average shares 89,614,205 62,171,590 61,985,422 Earnings per share available to common shareholders Basic $ 1.95 $ 1.57 $ 1.45 Diluted $ 1.93 $ 1.56 $ 1.43 First Financial had warrants outstanding to purchase the Company's common stock as of December 31, 2018 . These warrants were acquired in the MSFG merger and represent the right to purchase 804,858 shares of First Financial's common stock at an exercise price of $10.62 per share and were exercised in January 2019. At December 31, 2017 and 2016, First Financial had warrants outstanding representing the right to purchase 104,200 shares and 114,678 shares of common stock at an exercise price of exercise price of $12.12 and expired on December 23, 2018. 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 period end price, there were no antidilutive options at December 31, 2018 , 2017 , or 2016 . As of December 31, 2018 , 2017 , and 2016 , First Financial was authorized to issue 10,000,000 preferred shares, however no preferred shares were issued or outstanding.

FAIR VALUE DISCLOSURES

FAIR VALUE DISCLOSURES	12 Months Ended
FAIR VALUE DISCLOSURES	Dec. 31, 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 December 31, 2018 Financial assets Cash and short-term investments $ 273,959 $ 273,959 $ 273,959 $ 0 $ 0 Investment securities held-to-maturity 429,328 424,118 0 424,118 0 Other investments 115,660 N/A N/A N/A N/A Loans held for sale 4,372 4,372 0 4,372 0 Loans and leases, net of ALLL 8,767,672 8,662,868 0 0 8,662,868 Accrued interest receivable 41,816 41,816 0 13,819 27,997 Financial liabilities Deposits Noninterest-bearing $ 2,492,434 $ 2,492,434 $ 0 $ 2,492,434 $ 0 Interest-bearing demand 2,307,071 2,307,071 0 2,307,071 0 Savings 3,167,325 3,167,325 0 3,167,325 0 Time 2,173,564 2,146,645 0 2,146,645 0 Total deposits 10,140,394 10,113,475 0 10,113,475 0 Short-term borrowings 1,040,691 1,040,691 1,040,691 0 0 Long-term debt 570,739 557,933 0 557,933 0 Accrued interest payable 12,126 12,126 2,035 10,091 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, net of ALLL 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 Noninterest-bearing $ 1,662,058 $ 1,662,058 $ 0 $ 1,662,058 $ 0 Interest-bearing demand 1,453,463 1,453,463 0 1,453,463 0 Savings 2,462,420 2,462,420 0 2,462,420 0 Time 1,317,105 1,306,674 0 1,306,674 0 Total 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 December 31, 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 declines 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 Assets/Liabilities (Dollars in thousands) Level 1 Level 2 Level 3 at Fair Value December 31, 2018 Assets Derivatives $ 0 $ 29,543 $ 0 $ 29,543 Investment securities available-for-sale 97 2,779,158 0 2,779,255 Total $ 97 $ 2,808,701 $ 0 $ 2,808,798 Liabilities Derivatives $ 0 $ 29,336 $ 0 $ 29,336 Fair Value Measurements Using Assets/Liabilities (Dollars in thousands) Level 1 Level 2 Level 3 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 December 31, 2018 Assets Impaired loans $ 0 $ 0 $ 1,320 OREO 0 0 1,089 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	12 Months Ended
BUSINESS COMBINATIONS	Dec. 31, 2018
Business Combinations [Abstract]
BUSINESS COMBINATIONS	Business Combination On April 1, 2018, First Financial 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 $676.2 million . The goodwill arising from the acquisition largely reflected synergies and cost savings resulting from combining the operations of the companies. First Financial incurred $37.8 million of merger related expenses related to the acquisition of MSFG during the year ended December 31, 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 8 – 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 1,043,424 Warrant consideration 14,460 Options consideration 1,577 Total purchase consideration 1,059,504 Assets acquired Cash 71,688 Investment securities available-for-sale 900,935 Investment securities held-to-maturity 171,423 Other investments 28,763 Loans 2,792,740 Premises and equipment 98,381 Intangible assets 42,887 Other assets 167,693 Assets held for sale 127,775 Total assets acquired 4,402,285 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 383,337 Goodwill $ 676,167 The fair value of net assets acquired includes fair value adjustments to certain loans that were not considered impaired as of the acquisition date as the Company believes that all contractual cash flows will be collected. The fair value adjustments were determined using discounted cash flows. In conjunction with the MSFG merger, First Financial acquired non-impaired loans with a fair value and gross contractual amounts receivable of $2.8 billion and $2.9 billion on the date of acquisition. 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. Twelve months ended December 31, (Dollars in thousands, except per share data) (Unaudited) 2018 2017 Pro Forma Condensed Combined Income Statement Information Net interest income $ 484,915 $ 454,579 Net income 221,122 130,402 Basic earnings per share $ 2.27 $ 1.34 Diluted earnings per share $ 2.25 $ 1.33

FIRST FINANCIAL BANCORP. (PAREN

FIRST FINANCIAL BANCORP. (PARENT COMPANY ONLY) FINANCIAL INFORMATION	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Condensed Financial Information of Parent Company Only Disclosure [Text Block]	First Financial Bancorp (Parent Company Only) Financial Information Balance Sheets December 31, (Dollars in thousands) 2018 2017 Assets Cash $ 86,878 $ 57,719 Investment securities, available for sale 694 442 Subordinated notes from subsidiaries 7,500 7,500 Investment in subsidiaries Commercial banks 2,078,655 970,290 Nonbanks 7,194 0 Total investment in subsidiaries 2,085,849 970,290 Premises and equipment 1,361 1,378 Other assets 71,817 26,778 Total assets $ 2,254,099 $ 1,064,107 Liabilities Subordinated debentures $ 171,416 $ 118,638 Dividends payable 465 10,965 Other liabilities 3,969 3,840 Total liabilities 175,850 133,443 Shareholders’ equity 2,078,249 930,664 Total liabilities and shareholders’ equity $ 2,254,099 $ 1,064,107 Statements of Income and Comprehensive Income Years Ended December 31, (Dollars in thousands) 2018 2017 2016 Income Interest income $ 23 $ 6 $ 48 Noninterest income 0 86 2,596 Dividends from subsidiaries 107,340 54,600 52,700 Total income 107,363 54,692 55,344 Expenses Interest expense 8,798 6,152 6,151 Salaries and employee benefits 6,413 5,519 5,445 Miscellaneous professional services 5,130 970 711 Other 5,648 4,819 4,841 Total expenses 25,989 17,460 17,148 Income before income taxes and equity in undistributed net earnings of subsidiaries 81,374 37,232 38,196 Income tax expense (benefit) (6,687 ) (7,080 ) (5,302 ) Equity in undistributed earnings (loss) of subsidiaries 84,534 52,475 45,028 Net income $ 172,595 $ 96,787 $ 88,526 Comprehensive income $ 153,670 $ 104,840 $ 90,663 Statements of Cash Flows Years Ended December 31, (Dollars in thousands) 2018 2017 2016 Operating activities Net income $ 172,595 $ 96,787 $ 88,526 Adjustments to reconcile net income to net cash provided by operating activities Equity in undistributed (earnings) loss of subsidiaries (84,534 ) (52,475 ) (45,028 ) Depreciation and amortization 194 193 192 Stock-based compensation expense 6,219 5,446 5,354 Deferred income taxes 739 (360 ) 584 (Decrease) increase in dividends payable (10,500 ) 579 135 Increase (decrease) in other liabilities 9,979 (889 ) (389 ) Decrease (increase) in other assets 16,346 (6,951 ) (9,065 ) Net cash provided by (used in) operating activities 111,038 42,330 40,309 Investing activities Capital contributions to subsidiaries (3,000 ) 0 (53,000 ) Net cash acquired (paid) from business combinations 11,353 0 0 Proceeds from calls and maturities of investment securities 0 0 5,978 Purchases of investment securities 0 0 (333 ) Net cash (used in) provided by investing activities 8,353 0 (47,355 ) Financing activities (Decrease) increase in short-term borrowings (8,333 ) 0 0 Cash dividends paid on common stock (79,655 ) (41,178 ) (39,125 ) Proceeds from exercise of stock options, net of shares purchased 284 341 801 Excess tax benefit on share-based compensation 0 0 264 Other (2,528 ) (3,059 ) (1,681 ) Net cash (used in) provided by financing activities (90,232 ) (43,896 ) (39,741 ) Net increase (decrease) in cash 29,159 (1,566 ) (46,787 ) Cash at beginning of year 57,719 59,285 106,072 Cash at end of year $ 86,878 $ 57,719 $ 59,285

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2018
Basis of Presentation Policy	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 years' amounts have been made to conform to current year presentation. Such reclassifications had no effect on net earnings.
Use of Estimates, Policy	Use of estimates. The preparation of Consolidated 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. Actual realized amounts could differ materially from those estimates.
Investment, Policy	Investment securities. First Financial classifies debt securities into three categories: HTM, trading and AFS. Management classifies investment securities into the appropriate category at the time of purchase and re-evaluates that classification as deemed appropriate. Investment securities are classified as HTM when First Financial has the positive intent and ability to hold the securities to maturity. HTM securities are recorded at amortized cost. Investment securities classified as trading are held principally for resale in the near-term and are recorded at fair value. Fair value is determined using quoted market prices. Gains or losses on trading securities, both realized and unrealized, are reported in noninterest income. Investment securities not classified as either HTM or trading are classified as AFS. AFS securities are recorded at fair value, with the unrealized gains and losses, net of tax, reported as a separate component of accumulated other comprehensive income (loss) in shareholders' equity. The amortized cost of investment securities classified as either HTM or AFS is adjusted for amortization of premiums and accretion of discounts to maturity, or in the case of mortgage-backed securities, over the estimated life of the security. Such amortization and accretion are considered an adjustment to the yield on the security and included in interest income from investments. Interest and dividends are included in interest income from investment securities in the Consolidated Statements of Income. Realized gains and losses are based on the amortized cost of the security sold using the specific identification method. AFS and HTM securities are reviewed quarterly for potential impairment. In performing this review, management considers the length of time and extent to which the fair value of the security has been less than amortized cost, the financial condition and near-term prospects of the issuer and the ability and intent of First Financial to hold the security for a period sufficient to allow for any anticipated recovery in fair value. If the fair value of a security is less than the amortized cost and the impairment is determined to be other-than-temporary, the security is written down, establishing a new and reduced cost basis. The related charge is recorded in the Consolidated Statements of Income. Other investments. Other investments include holdings in FRB stock and FHLB stock, which are both carried at cost, as well as equity securities which are carried at fair value. Changes in the fair value of equity securities are recorded Other noninterest income in the Consolidated Statements of Income.
Finance, Loan and Lease Receivables, Held-for-sale, Policy [Policy Text Block]	Loans held for sale. Loans held for sale consist of residential real estate loans newly originated for the purpose of sale to third parties, and in certain circumstances, loans previously originated that have been specifically identified by management for sale based on predetermined criteria. Loans originated to held for sale status are carried at fair value. Any subsequent change in the carrying value of transferred loans, not to exceed original cost, is recorded in the Consolidated Statements of Income. First Financial sells loans with servicing retained or released depending on pricing and market conditions.
Finance, Loans and Leases Receivable, Policy	Loans and leases. Loans and leases for which First Financial has the intent and ability to hold for the foreseeable future, or until maturity or payoff, are classified in the Consolidated Balance Sheets as loans and leases. Loans and leases are carried at the principal amount outstanding, net of unamortized deferred loan origination fees and costs, and net of unearned income. Loan origination and commitment fees received, as well as certain direct loan origination costs paid, are deferred, and the net amount is amortized as an adjustment to the related loan's yield. Interest income on loans and leases is recorded on an accrual basis. 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 classified as nonaccrual are applied as a reduction to the carrying value of the loan. A loan may return to accrual status if collection of future principal and interest payments is no longer doubtful. 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. Accretion of the difference between the carrying value of the loans and the expected cash flows (accretable difference) is recognized on purchased impaired loans through interest income. Acquired loans outside of the scope of FASB ASC Topic 310-30 are accounted for under FASB ASC Topic 310-20, Receivables-Nonrefundable Fees and Costs. Discounts created when the loans were recorded at their estimated fair values at acquisition are amortized over the remaining term of the loan as an adjustment to the related loan's yield. The accrual of interest income is discontinued when the collection of a loan or interest, in whole or in part, is doubtful.
Loans and Leases Receivable, Allowance for Loan Losses Policy	Allowance for loan and lease losses. For each reporting period, 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. Management's determination of the adequacy of the ALLL is based on an assessment of the probable incurred loan and lease losses inherent in the portfolio given the conditions at the time. 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 through payments from the borrower or the liquidation of collateral. Commercial loan and lease relationships greater than $250,000 that are considered impaired, or designated as a TDR, are evaluated to determine the need for a specific allowance based on the borrower's overall financial condition, resources, payment record, guarantor support and the realizable value of any collateral. The allowance for non-impaired commercial loans and leases, as well as impaired commercial loan and lease relationships less than $250,000 , includes a process of estimating the probable losses incurred in the portfolio by loan type, based on First Financial's internal system of credit risk ratings and historical loss data. These estimates may also be adjusted based upon trends in the values of the underlying collateral, delinquent and nonaccrual loans, prevailing economic conditions and changes in lending strategies, among other influencing factors. Consumer loans are generally evaluated by loan type, as these loans exhibit homogeneous characteristics. The allowance for consumer loans, which includes residential real estate, installment, home equity, credit card loans and overdrafts, is established by estimating probable losses incurred in each particular category of consumer loans. The estimate of losses is primarily based on historical loss rates for each category and may be adjusted for trends in delinquent and nonaccrual loans, prevailing economic conditions and other significant influencing factors. Consumer loans greater than $250,000 classified as TDRs are individually evaluated to determine an appropriate allowance. For purchased impaired loans, expected cash flows are re-estimated periodically with declines in gross expected cash flows recorded as provision expense during the period.
Commitments and Contingencies, Policy	Reserve for unfunded commitments . First Financial maintains a reserve that it considers sufficient to absorb probable losses incurred in standby letters of credit and outstanding loan commitments. First Financial determines the adequacy of the reserve based upon an evaluation of the unfunded credit facilities, which includes consideration of historical commitment utilization experience, credit risk ratings and historical loss rates, consistent with the Company's ALLL methodology. The reserve for unfunded commitments is included in Accrued interest and other liabilities on the Consolidated Balance Sheets and adjustments are recorded in Other noninterest expense in the Consolidated Statements of Income. 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 losses incurred in letters of credit and outstanding loan commitments and records the reserve within Accrued interest and other liabilities on the Consolidated Balance Sheets.
Property, Plant and Equipment, Policy	Premises and equipment. Premises and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation and amortization are principally computed on the straight-line method over the estimated useful lives of the assets. Useful lives generally range from 10 to 40 years for building and building improvements; 3 to 10 years for furniture, fixtures and equipment; and 3 to 5 years for software, hardware and data handling equipment. Land improvements are depreciated over 20 years and leasehold improvements are depreciated over the lesser of the term of the respective lease or the useful life of the asset. Premises and equipment are evaluated for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Maintenance and repairs are expensed as incurred.
Bank Owned Life Insurance [Policy Text Block]	Bank-owned life insurance. First Financial purchases life insurance policies on the lives of certain employees and is the owner and beneficiary of the policies. The Bank invests in these policies to provide an efficient form of funding for long-term retirement and other employee benefits costs. The policies are included within Accrued interest and other assets in the Consolidated Balance Sheets at each policy’s respective cash surrender value with changes recorded in Other noninterest income in the Consolidated Statements of Income.
Goodwill and Intangible Assets, Policy	Goodwill. Under accounting for business combinations, the net assets of entities acquired by First Financial are recorded at their estimated fair value at the date of acquisition. The excess cost of the acquisition over the fair value of net assets acquired is recorded as goodwill. Goodwill and intangible assets deemed to have indefinite lives, if any, are not amortized, but are subject to annual impairment tests. The Company is required to evaluate goodwill for impairment on an annual basis or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. First Financial performs its annual impairment test effective October 1, absent events or changes in circumstances that indicate the carrying value of goodwill may not be recoverable. The Company’s goodwill is accounted for in a single reporting unit representing the consolidated entity. Fair value is estimated using the market capitalization of the Company as of the annual impairment testing date. First Financial also utilizes additional information and analyses to corroborate the use of the Company’s market capitalization as a proper indicator of fair value for purposes of the annual goodwill impairment test.
Goodwill and Intangible Assets, Goodwill, Policy	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. 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 annual impairment test of goodwill as of October 1, 2018 and no impairment was indicated. As of December 31, 2018 , no events or changes in circumstances indicated that the fair value of a reporting unit was below its carrying value.
Core Deposit Intangibles Policy	Core deposit intangibles. CDI represent the estimated value of acquired customer deposit relationships. CDI are recorded at fair value at the date of acquisition and are based on a discounted cash flow methodology that gives appropriate consideration to expected customer attrition rates, cost of the deposit base, reserve requirements and the net maintenance cost attributable to customer deposits. Core deposit intangibles are recorded in Other intangibles on the Consolidated Balance Sheets and are amortized on an accelerated basis over their estimated useful lives.
Other Real Estate Owned Policy	Other real estate owned. OREO consists of properties acquired by the Company primarily through the loan foreclosure or repossession process, or other resolution activity that results in partial or total satisfaction of problem loans. OREO properties are recorded at fair value, less estimated disposal costs (net realizable value). Losses arising at the time of acquisition of such properties are charged against the ALLL. Management performs periodic valuations to assess the adequacy of recorded OREO balances and subsequent changes in the carrying value of OREO properties are recorded in the Consolidated Statements of Income. Improvements to OREO properties may be capitalized if the improvements contribute to the overall value of the property, but may not be capitalized in excess of the net realizable value of the property. When management disposes of an OREO property, any gains or losses realized at the time of disposal are reflected in the Consolidated Statements of Income.
Affordable Housing Program Policy	Affordable housing projects. First Financial has investments in certain qualified affordable housing projects. These projects are indirect federal subsidies 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 properties to qualified tenants, resulting in 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.
Investments in Historic Tax Credits [Policy Text Block]	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. The Company’s recorded investment in these entities is carried in Accrued interest and other assets on the Consolidated Balance Sheets.
Income Tax, Policy	Income taxes. First Financial and its subsidiaries file a consolidated federal income tax return. Each subsidiary provides for income taxes on a separate return basis, and remits to First Financial amounts determined to be currently payable. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Interest and penalties on income tax assessments or income tax refunds are recognized as a component of noninterest expense in the Consolidated Statements of Income.
Pension and Other Postretirement Plans, Pensions, Policy	Pension. First Financial sponsors a non-contributory defined benefit pension plan covering substantially all employees. The measurement of the accrued benefit liability and the annual pension expense involves actuarial and economic assumptions, which include the discount rate, the expected return on plan assets and the rate of compensation increase.
Derivatives, Policy	Derivative instruments. First Financial accounts for its derivative financial instruments in accordance with FASB ASC Topic 815, Derivatives and Hedging. FASB ASC Topic 815 requires all derivative instruments to be carried at fair value on the balance sheet. The accounting for changes in the fair value of derivatives is based on the intended use of the derivative and the resulting designation. Derivatives used to hedge the exposure to changes in the fair value of an asset, liability or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Derivatives used to hedge the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. 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. Upon entering into an interest rate swap with a borrower, the Bank simultaneously enters into an offsetting swap agreement with an institutional counterparty, with substantially matching terms. These matched interest rate swap agreements generally involve the receipt by First Financial of floating rate amounts from the counterparties in exchange for payments to these counterparties by First Financial of fixed rate amounts received from commercial borrowers over the life of the agreements. First Financial's matched interest rate swaps qualify as derivatives, but are not designated as hedging instruments. The net interest receivable or payable on matched interest rate swaps is accrued and recognized as an adjustment to interest income. The fair values of client derivatives are included within Accrued interest and other assets and Accrued interest and other liabilities in the Consolidated Balance Sheets. 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 fair value of these agreements is recorded in the Consolidated Balance Sheets in Accrued interest and other liabilities. 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 and Loans held for sale. The fair value of these agreements is recorded in the Consolidated Balance Sheets in Accrued interest and other assets.
Share-based Compensation, Option and Incentive Plans Policy	Stock-based compensation. First Financial grants stock-based awards, including restricted stock awards and options to purchase the Company’s common stock. Stock option grants are for a fixed number of shares to employees and directors with an exercise price equal to the fair value of the shares at the date of grant. Stock-based compensation expense is recognized in the Consolidated Statements of Income on a straight-line basis over the vesting period. As compensation expense is recognized, a deferred tax asset is recorded that represents an estimate of the future tax deduction from exercise. At the time stock-based awards are exercised, canceled or expire, First Financial may be required to recognize an adjustment to tax expense.
Earnings Per Share, Policy	Earnings per share. Basic earnings per common share is computed by dividing net income available to common shareholders by the weighted average number of shares of common stock outstanding during the period. Diluted earnings per common share is computed by dividing net income available to common shareholders by the weighted average number of common shares outstanding, unvested shares and dilutive common stock equivalents outstanding during the period. Common stock equivalents, which consist of common stock issuable under the assumed exercise of stock options granted under First Financial's stock-based compensation plans and the assumed conversion of common stock warrants, are calculated using the treasury stock method.
Cash and Cash Equivalents, Policy	Cash and due from banks. Cash and due from banks consist of currency, coin and cash items due from banks. Cash items due from banks include noninterest bearing deposits held at other banks.
Loans and Leases Receivable, Past Due Status, Policy [Policy Text Block]	Delinquency. Loans are considered past due or delinquent when the contractual principal or interest due in accordance with the terms of the loan agreement or any portion thereof remains unpaid after the due date of the scheduled payment.
Loans and Leases Receivable, Nonaccrual Loan and Lease Status, Policy	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 to adhere to contractual payment terms by the borrower, 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 none of the principal and interest is due and unpaid, and the Bank expects repayment of the remaining contractual principal and interest. 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 [Policy Text Block]	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.
Impaired Financing Receivable, Policy	Loans classified as nonaccrual and loans modified as TDRs are considered impaired.
Loans and Leases Receivable, Real Estate Acquired Through Foreclosure, Policy	OREO is comprised of properties acquired by the Company primarily through the loan foreclosure or repossession process, or other resolution activities that result in partial or total satisfaction of problem loans.
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 declines 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.
Segment Reporting, Policy	Segments and related information. While the Company monitors the operating results of its six lines of business, operations are managed and financial performance is evaluated on a consolidated basis. Accordingly, and consistent with prior years, all of the Company's operations are considered by management to be aggregated in one reportable operating segment.
Other Contract-Mortgage
Derivatives, Methods of Accounting, Hedging 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 and loans held for sale.
Credit Risk
Derivatives, Methods of Accounting, Hedging Derivatives	First Financial manages this 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	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)	12 Months Ended
INVESTMENTS (Tables)	Dec. 31, 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 December 31, 2018 : Held-to-maturity Available-for-sale (Dollars in thousands) Amortized cost Unrecognized gain Unrecognized loss Fair value Amortized cost Unrealized gain Unrealized loss Fair value U.S. Treasuries $ 0 $ 0 $ 0 $ 0 $ 99 $ 0 $ (2 ) $ 97 Securities of U.S. government agencies and corporations 0 0 0 0 32,095 57 (233 ) 31,919 Mortgage-backed securities - residential 25,565 0 (1,045 ) 24,520 565,071 691 (7,163 ) 558,599 Mortgage-backed securities - commercial 147,780 258 (4,385 ) 143,653 423,797 819 (3,581 ) 421,035 Collateralized mortgage obligations 12,540 0 (633 ) 11,907 928,586 4,319 (6,158 ) 926,747 Obligations of state and other political subdivisions 243,443 1,954 (1,359 ) 244,038 257,300 2,554 (1,429 ) 258,425 Asset-backed securities 0 0 0 0 511,430 611 (2,810 ) 509,231 Other securities 0 0 0 0 73,948 358 (1,104 ) 73,202 Total $ 429,328 $ 2,212 $ (7,422 ) $ 424,118 $ 2,792,326 $ 9,409 $ (22,480 ) $ 2,779,255 The following is a summary of HTM and AFS investment securities as of December 31, 2017 : Held-to-maturity Available-for-sale (Dollars in thousands) Amortized Unrecognized 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 December 31, 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 Due in one year or less $ 0 $ 0 $ 5,972 $ 5,977 Due after one year through five years 275 279 63,995 64,040 Due after five years through ten years 21,110 21,374 133,360 133,594 Due after ten years 222,058 222,385 160,115 160,032 Mortgage-backed securities - residential 25,565 24,520 565,071 558,599 Mortgage-backed securities - commercial 147,780 143,653 423,797 421,035 Collateralized mortgage obligations 12,540 11,907 928,586 926,747 Asset-backed securities 0 0 511,430 509,231 Total $ 429,328 $ 424,118 $ 2,792,326 $ 2,779,255
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: December 31, 2018 Less than 12 months 12 months or more Total (Dollars in thousands) Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss U.S. Treasuries $ 0 $ 0 $ 97 $ (2 ) $ 97 $ (2 ) Securities of U.S. government agencies and corporations 0 0 16,777 (233 ) 16,777 (233 ) Mortgage-backed securities - residential 186,029 (935 ) 264,795 (7,273 ) 450,824 (8,208 ) Mortgage-backed securities - commercial 147,754 (369 ) 232,363 (7,597 ) 380,117 (7,966 ) Collateralized mortgage obligations 194,795 (1,546 ) 240,514 (5,245 ) 435,309 (6,791 ) Obligations of state and other political subdivisions 62,805 (299 ) 86,644 (2,489 ) 149,449 (2,788 ) Asset-backed securities 336,437 (2,312 ) 37,105 (498 ) 373,542 (2,810 ) Other securities 33,752 (884 ) 4,570 (220 ) 38,322 (1,104 ) Total $ 961,572 $ (6,345 ) $ 882,865 $ (23,557 ) $ 1,844,437 $ (29,902 ) December 31, 2017 Less than 12 months 12 months or more Total (Dollars in thousands) Fair Unrealized Fair Unrealized Fair Unrealized 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 (Tables)

LOANS (Tables)	12 Months Ended
LOANS (Tables)	Dec. 31, 2018
LOANS - Carrying Amount of Accretable Yield for Purchased Impaired and Nonimpaired Loans [Abstract]
Commercial and Consumer Credit Exposure by Risk Attribute	Commercial and consumer credit exposure by risk attribute was as follows: As of December 31, 2018 Real Estate (Dollars in thousands) Commercial & industrial Construction Commercial Lease financing Total Pass $ 2,432,834 $ 548,323 $ 3,664,434 $ 90,902 $ 6,736,493 Special Mention 24,594 603 38,653 0 63,850 Substandard 57,233 9 51,594 2,513 111,349 Doubtful 0 0 0 0 0 Total $ 2,514,661 $ 548,935 $ 3,754,681 $ 93,415 $ 6,911,692 Residential real estate Home Equity Installment Credit card Total Performing $ 939,936 $ 811,108 $ 93,038 $ 46,382 $ 1,890,464 Nonperforming 15,710 6,174 174 0 22,058 Total $ 955,646 $ 817,282 $ 93,212 $ 46,382 $ 1,912,522 As of December 31, 2017 Real Estate (Dollars in thousands) Commercial & industrial Construction Commercial Lease 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 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 nonaccrual loans, was as follows: As of December 31, 2018 (Dollars in thousands) 30 – 59 days past due 60 – 89 days past due > 90 days past due Total past due Current Subtotal Purchased impaired Total > 90 days past due and still accruing Loans Commercial & industrial $ 13,369 $ 41 $ 7,423 $ 20,833 $ 2,488,450 $ 2,509,283 $ 5,378 $ 2,514,661 $ 0 Lease financing 352 0 0 352 93,063 93,415 0 93,415 0 Construction real estate 0 0 0 0 548,687 548,687 248 548,935 0 Commercial real estate 6,279 1,158 12,644 20,081 3,682,455 3,702,536 52,145 3,754,681 0 Residential real estate 11,060 2,976 4,535 18,571 902,404 920,975 34,671 955,646 0 Home equity 5,245 1,228 2,578 9,051 804,835 813,886 3,396 817,282 0 Installment 420 37 145 602 92,128 92,730 482 93,212 0 Credit card 541 96 63 700 45,682 46,382 0 46,382 63 Total $ 37,266 $ 5,536 $ 27,388 $ 70,190 $ 8,657,704 $ 8,727,894 $ 96,320 $ 8,824,214 $ 63 As of December 31, 2017 (Dollars in thousands) 30 - 59 days past due 60 - 89 days past due > 90 days past due Total past due Current Subtotal Purchased impaired Total > 90 days past due and still accruing 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 table provides information on loan modifications classified as TDRs during the years ended December 31, 2018 , 2017 and 2016 : Years ended December 31, 2018 2017 2016 (Dollars in thousands) Number of loans Pre-modification loan balance Period end balance Number of loans Pre-modification loan balance Period end balance Number of loans Pre-modification loan balance Period end balance Commercial & industrial 17 $ 23,943 $ 23,890 7 $ 5,724 $ 5,661 18 $ 3,402 $ 3,508 Construction real estate 0 0 0 0 0 0 0 0 0 Commercial real estate 8 3,385 3,150 8 1,816 1,758 16 5,200 4,752 Residential real estate 13 1,148 1,073 6 416 315 5 840 787 Home equity 5 95 192 1 39 39 5 165 156 Installment 0 0 0 0 0 0 3 9 9 Total 43 $ 28,571 $ 28,305 22 $ 7,995 $ 7,773 47 $ 9,616 $ 9,212
Loans Restructured, Modifications	The following table provides information on how TDRs were modified during the years ended December 31, 2018 , 2017 and 2016 : Years Ended December 31, (Dollars in thousands) 2018 2017 2016 Extended maturities $ 4,093 $ 3,261 $ 2,571 Adjusted interest rates 52 2,767 0 Combination of rate and maturity changes 0 489 3,046 Forbearance 23,175 1,181 88 Other (1) 985 75 3,507 Total $ 28,305 $ 7,773 $ 9,212 (1) Other includes covenant modifications and other concessions or combination of concessions that do not consist of interest rate adjustments, forbearance and maturity extensions.
Loan Restructuring, Loans with a Payment Default Within 12 Months of Loan Modification
Nonaccrual, Restructured and Impaired Loans	The following table provides information on impaired loans, excluding purchased impaired loans, as of December 31: (Dollars in thousands) 2018 2017 2016 Impaired loans Nonaccrual loans (1) Commercial & industrial $ 30,925 $ 5,229 $ 2,419 Lease financing 22 82 195 Construction real estate 9 29 0 Commercial real estate 20,500 10,616 6,098 Residential real estate 13,495 4,140 5,251 Home equity 5,580 3,743 3,400 Installment 169 243 367 Total nonaccrual loans 70,700 24,082 17,730 Accruing troubled debt restructurings 16,109 17,545 30,240 Total impaired loans $ 86,809 $ 41,627 $ 47,970 Interest income effect Gross amount of interest that would have been recorded under original terms $ 4,656 $ 3,397 $ 2,848 Interest included in income Nonaccrual loans 715 535 375 Troubled debt restructurings 642 710 876 Total interest included in income 1,357 1,245 1,251 Net impact on interest income $ 3,299 $ 2,152 $ 1,597 Commitments outstanding to borrowers with nonaccrual loans $ 200 $ 0 $ 0 (1) Nonaccrual loans include nonaccrual TDRs of $22.4 million , $6.4 million and $5.1 million as of December 31, 2018 , 2017 and 2016 , respectively.
Investment in Impaired Loans	First Financial's investment in impaired loans, excluding purchased impaired loans, is as follows: December 31, 2018 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 $ 36,694 $ 42,561 $ 0 $ 7,162 $ 8,460 $ 0 Lease financing 22 22 0 82 82 0 Construction real estate 9 26 0 29 60 0 Commercial real estate 23,513 31,375 0 18,423 20,837 0 Residential real estate 17,297 19,975 0 6,876 8,145 0 Home equity 6,351 7,461 0 4,356 5,399 0 Installment 174 563 0 255 422 0 Total 84,060 101,983 0 37,183 43,405 0 Loans with an allowance recorded Commercial & industrial 939 939 667 169 169 169 Lease financing 0 0 0 0 0 0 Construction real estate 0 0 0 0 0 0 Commercial real estate 1,509 1,509 461 3,119 3,120 448 Residential real estate 301 301 32 1,056 1,063 160 Home equity 0 0 0 100 100 2 Installment 0 0 0 0 0 0 Total 2,749 2,749 1,160 4,444 4,452 779 Total Commercial & industrial 37,633 43,500 667 7,331 8,629 169 Lease financing 22 22 0 82 82 0 Construction real estate 9 26 0 29 60 0 Commercial real estate 25,022 32,884 461 21,542 23,957 448 Residential real estate 17,598 20,276 32 7,932 9,208 160 Home equity 6,351 7,461 0 4,456 5,499 2 Installment 174 563 0 255 422 0 Total $ 86,809 $ 104,732 $ 1,160 $ 41,627 $ 47,857 $ 779 Years ended December 31, 2018 2017 2016 (Dollars in thousands) Average balance Interest Average balance Interest income recognized Average Interest Loans with no related allowance recorded Commercial & industrial $ 14,498 $ 360 $ 13,167 $ 280 $ 13,619 $ 309 Lease financing 21 0 112 4 150 3 Construction real estate 20 2 601 1 0 0 Commercial real estate 24,738 490 20,935 563 14,252 357 Residential real estate 11,359 301 7,616 196 7,752 199 Home equity 5,541 114 4,032 99 4,830 86 Installment 274 2 332 4 366 7 Total 56,451 1,269 46,795 1,147 40,969 961 Loans with an allowance recorded Commercial & industrial 900 44 1,204 28 1,098 37 Lease financing 0 0 0 0 214 8 Construction real estate 0 0 0 0 0 0 Commercial real estate 1,402 18 2,634 40 7,792 211 Residential real estate 895 23 1,112 26 1,374 30 Home equity 80 3 101 4 101 4 Installment 0 0 0 0 0 0 Total 3,277 88 5,051 98 10,579 290 Total Commercial & industrial 15,398 404 14,371 308 14,717 346 Lease financing 21 0 112 4 364 11 Construction real estate 20 2 601 1 0 0 Commercial real estate 26,140 508 23,569 603 22,044 568 Residential real estate 12,254 324 8,728 222 9,126 229 Home equity 5,621 117 4,133 103 4,931 90 Installment 274 2 332 4 366 7 Total $ 59,728 $ 1,357 $ 51,846 $ 1,245 $ 51,548 $ 1,251
Changes in Other Real Estate Owned	Changes in OREO were as follows: Years ended December 31, (Dollars in thousands) 2018 2017 2016 Balance at beginning of year $ 2,781 $ 6,284 $ 13,254 Additions Commercial 1,269 1,732 1,850 Residential 1,913 2,387 1,022 Total additions 3,182 4,119 2,872 Disposals Commercial (2,967 ) (5,409 ) (6,993 ) Residential (830 ) (1,574 ) (2,363 ) Total disposals (3,797 ) (6,983 ) (9,356 ) Valuation adjustments Commercial (355 ) (439 ) (345 ) Residential (410 ) (200 ) (141 ) Total valuation adjustments (765 ) (639 ) (486 ) Balance at end of year $ 1,401 $ 2,781 $ 6,284

ALLOWANCE FOR LOAN AND LEASE _2

ALLOWANCE FOR LOAN AND LEASE LOSSES (Tables)	12 Months Ended
ALLOWANCE FOR LOAN AND LEASE LOSSES (Tables)	Dec. 31, 2018
Receivables [Abstract]
Changes in the Allowance for Loan and Lease Losses for the Previous Three Years	Changes in the ALLL by loan category as of December 31 were as follows: 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 year $ 17,598 $ 675 $ 3,577 $ 20,930 $ 4,683 $ 4,935 $ 307 $ 1,316 $ 54,021 Provision for loan and lease losses 10,615 454 (310 ) 847 492 829 (85 ) 1,744 14,586 Gross charge-offs (11,533 ) 0 0 (4,835 ) (422 ) (1,725 ) (435 ) (1,720 ) (20,670 ) Recoveries 2,066 1 146 4,106 211 1,309 575 191 8,605 Total net charge-offs (9,467 ) 1 146 (729 ) (211 ) (416 ) 140 (1,529 ) (12,065 ) Ending allowance for loan and lease losses $ 18,746 $ 1,130 $ 3,413 $ 21,048 $ 4,964 $ 5,348 $ 362 $ 1,531 $ 56,542 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 year $ 19,225 $ 716 $ 3,282 $ 26,540 $ 3,208 $ 3,043 $ 388 $ 1,559 $ 57,961 Provision for loan and lease losses 6,917 (42 ) 207 (7,291 ) 1,695 1,778 (90 ) 408 3,582 Gross charge-offs (10,194 ) 0 (1 ) (1,038 ) (435 ) (913 ) (225 ) (857 ) (13,663 ) Recoveries 1,650 1 89 2,719 215 1,027 234 206 6,141 Total net charge-offs (8,544 ) 1 88 1,681 (220 ) 114 9 (651 ) (7,522 ) Ending allowance for loan and lease losses $ 17,598 $ 675 $ 3,577 $ 20,930 $ 4,683 $ 4,935 $ 307 $ 1,316 $ 54,021 2016 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 year $ 16,995 $ 821 $ 1,810 $ 23,656 $ 4,014 $ 3,943 $ 386 $ 1,773 $ 53,398 Provision for loan and lease losses 3,705 (106 ) 1,280 5,365 (655 ) (175 ) 53 673 10,140 Gross charge-offs (2,630 ) 0 (93 ) (4,983 ) (387 ) (1,445 ) (386 ) (1,190 ) (11,114 ) Recoveries 1,155 1 285 2,502 236 720 335 303 5,537 Total net charge-offs (1,475 ) 1 192 (2,481 ) (151 ) (725 ) (51 ) (887 ) (5,577 ) Ending allowance for loan and lease losses $ 19,225 $ 716 $ 3,282 $ 26,540 $ 3,208 $ 3,043 $ 388 $ 1,559 $ 57,961
Allowance for Loan and Lease Losses by Classification	Changes in the ALLL by loan category as of December 31 were as follows: 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 year $ 17,598 $ 675 $ 3,577 $ 20,930 $ 4,683 $ 4,935 $ 307 $ 1,316 $ 54,021 Provision for loan and lease losses 10,615 454 (310 ) 847 492 829 (85 ) 1,744 14,586 Gross charge-offs (11,533 ) 0 0 (4,835 ) (422 ) (1,725 ) (435 ) (1,720 ) (20,670 ) Recoveries 2,066 1 146 4,106 211 1,309 575 191 8,605 Total net charge-offs (9,467 ) 1 146 (729 ) (211 ) (416 ) 140 (1,529 ) (12,065 ) Ending allowance for loan and lease losses $ 18,746 $ 1,130 $ 3,413 $ 21,048 $ 4,964 $ 5,348 $ 362 $ 1,531 $ 56,542 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 year $ 19,225 $ 716 $ 3,282 $ 26,540 $ 3,208 $ 3,043 $ 388 $ 1,559 $ 57,961 Provision for loan and lease losses 6,917 (42 ) 207 (7,291 ) 1,695 1,778 (90 ) 408 3,582 Gross charge-offs (10,194 ) 0 (1 ) (1,038 ) (435 ) (913 ) (225 ) (857 ) (13,663 ) Recoveries 1,650 1 89 2,719 215 1,027 234 206 6,141 Total net charge-offs (8,544 ) 1 88 1,681 (220 ) 114 9 (651 ) (7,522 ) Ending allowance for loan and lease losses $ 17,598 $ 675 $ 3,577 $ 20,930 $ 4,683 $ 4,935 $ 307 $ 1,316 $ 54,021 2016 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 year $ 16,995 $ 821 $ 1,810 $ 23,656 $ 4,014 $ 3,943 $ 386 $ 1,773 $ 53,398 Provision for loan and lease losses 3,705 (106 ) 1,280 5,365 (655 ) (175 ) 53 673 10,140 Gross charge-offs (2,630 ) 0 (93 ) (4,983 ) (387 ) (1,445 ) (386 ) (1,190 ) (11,114 ) Recoveries 1,155 1 285 2,502 236 720 335 303 5,537 Total net charge-offs (1,475 ) 1 192 (2,481 ) (151 ) (725 ) (51 ) (887 ) (5,577 ) Ending allowance for loan and lease losses $ 19,225 $ 716 $ 3,282 $ 26,540 $ 3,208 $ 3,043 $ 388 $ 1,559 $ 57,961 The ALLL balance and the recorded investment in loans by portfolio segment and based on impairment method as of December 31 were as follows: December 31, 2018 Real Estate (Dollars in thousands) Commercial & industrial Lease financing Construction Commercial Residential Home equity Installment Credit card Total Ending allowance on loans individually evaluated for impairment $ 667 $ 0 $ 0 $ 461 $ 32 $ 0 $ 0 $ 0 $ 1,160 Ending allowance on loans collectively evaluated for impairment 18,079 1,130 3,413 20,587 4,932 5,348 362 1,531 55,382 Ending allowance for loan and lease losses $ 18,746 $ 1,130 $ 3,413 $ 21,048 $ 4,964 $ 5,348 $ 362 $ 1,531 $ 56,542 Loans and Leases Ending balance of loans individually evaluated for impairment $ 37,633 $ 22 $ 9 $ 25,022 $ 17,598 $ 6,351 $ 174 $ 0 $ 86,809 Ending balance of loans collectively evaluated for impairment 2,477,028 93,393 548,926 3,729,659 938,048 810,931 93,038 46,382 8,737,405 Total loans $ 2,514,661 $ 93,415 $ 548,935 $ 3,754,681 $ 955,646 $ 817,282 $ 93,212 $ 46,382 $ 8,824,214 December 31, 2017 Real Estate (Dollars in thousands) Commercial & industrial Lease financing Construction Commercial Residential Home equity Installment Credit card Total Ending allowance on loans individually evaluated for impairment $ 169 $ 0 $ 0 $ 448 $ 160 $ 2 $ 0 $ 0 $ 779 Ending allowance on loans 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 and Leases Ending balance of loans individually evaluated for impairment $ 7,331 $ 82 $ 29 $ 21,542 $ 7,932 $ 4,456 $ 255 $ 0 $ 41,627 Ending balance of loans 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

PREMISES AND EQUIPMENT (Tables)

PREMISES AND EQUIPMENT (Tables)	12 Months Ended
PREMISES AND EQUIPMENT (Tables)	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Table Text Block]	Premises and equipment at December 31 were as follows: (Dollars in thousands) 2018 2017 Land and land improvements $ 57,701 $ 41,711 Buildings 161,817 104,576 Furniture and fixtures 66,567 55,165 Leasehold improvements 29,086 19,377 Construction in progress 5,731 1,721 320,902 222,550 Less: Accumulated depreciation and amortization 105,250 97,514 Total $ 215,652 $ 125,036
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	First Financial's future minimum lease payments for operating leases are as follows: (Dollars in thousands) 2019 $ 9,568 2020 9,179 2021 8,284 2022 5,016 2023 4,269 Thereafter 15,496 Total $ 51,812

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS GOODWILL (Tables)	12 Months Ended
GOODWILL AND OTHER INTANGIBLE ASSETS GOODWILL (Tables)	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in Carrying Amount of Goodwill	Changes in the carrying amount of goodwill for the years ended December 31, 2018 , 2017 and 2016 are shown below. (Dollars in thousands) 2018 2017 2016 Balance at beginning of year $ 204,084 $ 204,084 $ 204,084 Goodwill resulting from business combinations 676,167 0 0 Balance at end of year $ 880,251 $ 204,084 $ 204,084
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	The estimated amortization expense of intangible assets for the next five years is as follows: (Dollars in thousands) 2019 $ 8,800 2020 7,010 2021 5,602 2022 3,417 2023 3,155

DEPOSITS (Tables)

DEPOSITS (Tables)	12 Months Ended
DEPOSITS (Tables)	Dec. 31, 2018
Deposits [Abstract]
Maturities of time deposits [Table Text Block]	Scheduled maturities of time deposits for the next five years were as follows: (Dollars in thousands) 2019 $ 1,407,996 2020 471,183 2021 163,575 2022 110,170 2023 20,112 Thereafter 528 Total $ 2,173,564

BORROWINGS (Tables)

BORROWINGS (Tables)	12 Months Ended
BORROWINGS (Tables)	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule Of Remaining Contractual Maturity Of Secured Borrowings And Class Of Collateral Pledged Under Repurchase Agreements Table [Table Text Block]	(Dollars in thousands) Overnight and Continuous Repurchase agreements Mortgage-backed securities $ 22,369 Collateralized mortgage obligations 62,222 Total $ 84,591
Schedule of Short-term Debt [Table Text Block]	The following is a summary of short-term borrowings for the last three years: 2018 2017 2016 (Dollars in thousands) Amount Rate Amount Rate Amount Rate At December 31, Federal funds purchased and securities sold under agreements to repurchase $ 183,591 1.65 % $ 72,265 0.19 % $ 120,212 0.12 % FHLB borrowings 857,100 2.48 % 742,300 1.43 % 687,700 0.66 % Total $ 1,040,691 2.33 % $ 814,565 1.32 % $ 807,912 0.58 % Average for the year Federal funds purchased and securities sold under agreements to repurchase $ 87,221 0.58 % $ 69,766 0.19 % $ 89,157 0.05 % FHLB borrowings 857,028 2.03 % 760,558 1.05 % 791,259 0.55 % Other short-term borrowings 3,178 4.36 % 41 4.07 % 41 3.56 % Total $ 947,427 1.90 % $ 830,365 0.98 % $ 880,457 0.50 % Maximum month-end balances Federal funds purchased and securities sold under agreements to repurchase $ 183,591 $ 130,633 $ 122,242 FHLB borrowings 1,170,800 957,700 1,035,000 Other short-term borrowings 10,000 0 0
Summary of Long-term Debt [Table Text Block]	The following is a summary of First Financial's long-term debt: 2018 2017 (Dollars in thousands) Amount Average Rate Amount Average Rate Subordinated debt $ 170,550 5.28 % $ 120,000 5.13 % Unamortized debt issuance costs (1,185 ) n/a (1,362 ) n/a FHLB 400,599 2.08 % 241 1.09 % Capital loan with municipality 775 0.00 % 775 0.00 % Total long-term debt $ 570,739 3.04 % $ 119,654 5.14 %
Schedule of Maturities of Long-term Debt [Table Text Block]	As of December 31, 2018 , First Financial's long-term debt matures as follows: (Dollars in thousands) 2019 $ 157,914 2020 104,274 2021 19,007 2022 49,404 2023 0 Thereafter 240,140 Total $ 570,739

DERIVATIVES (Tables)

DERIVATIVES (Tables)	12 Months Ended
DERIVATIVES (Tables)	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Derivative Financial Instruments and Balances	The following table details the location and amounts recognized in the Consolidated Balance Sheets for client derivatives: December 31, 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 Matched interest rate swaps with borrower Accrued interest and other assets and other liabilities $ 1,359,990 $ 17,402 $ (11,787 ) $ 837,040 $ 7,153 $ (5,529 ) Matched interest rate swaps with counterparty Accrued interest and other liabilities 1,359,990 11,787 (17,401 ) 837,040 5,529 (7,158 ) Total $ 2,719,980 $ 29,189 $ (29,188 ) $ 1,674,080 $ 12,682 $ (12,687 )
Disclosure by Type of Financial Instrument [Table Text Block]	The following table discloses the gross and net amounts of client derivative liabilities recognized in the Consolidated Balance Sheets: December 31, 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 $ 29,189 $ (14,577 ) $ 14,612 $ 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 December 31, 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 $ 1,359,990 6.2 $ 5,615 4.70 % 4.67 % Pay fixed, matched interest rate swaps with counterparty 1,359,990 6.2 (5,614 ) 4.67 % 4.70 % Total client derivatives $ 2,719,980 6.2 $ 1 4.68 % 4.68 %

RELATED PARTIES TRANSACTIONS (T

RELATED PARTIES TRANSACTIONS (Tables)	12 Months Ended
RELATED PARTIES TRANSACTIONS (Tables)	Dec. 31, 2018
Related Party Transactions [Abstract]
Schedule of Loans to Related Parties [Table Text Block]	Loans to directors, executive officers, principal holders of First Financial’s common stock and certain related persons were as follows: (Dollars in thousands) 2018 Beginning balance $ 9,873 Additions 2,108 Deductions (9,249 ) Ending balance $ 2,732 Loans 90 days or more past due $ 0

INCOME TAXES INCOME TAXES (Tabl

INCOME TAXES INCOME TAXES (Tables)	12 Months Ended
INCOME TAXES INCOME TAXES (Tables)	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	Income tax expense consisted of the following components: (Dollars in thousands) 2018 2017 2016 Current expense Federal $ 34,330 $ 22,599 $ 40,537 State 1,029 1,265 1,322 Total current expense 35,359 23,864 41,859 Deferred expense (benefit) Federal 4,675 (4,657 ) 528 State 1,592 169 (182 ) Total deferred expense (benefit) 6,267 (4,488 ) 346 Income tax expense $ 41,626 $ 19,376 $ 42,205
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The difference between the federal income tax rates applied to income before income taxes, and the effective rates were due to the following: (Dollars in thousands) 2018 2017 2016 Income taxes computed at federal statutory rate on income before income taxes (21% in 2018; 35% in 2017 and 2016) $ 44,986 $ 40,657 $ 45,756 Benefit from tax-exempt income (4,499 ) (3,427 ) (2,911 ) Tax credits (5,439 ) (16,806 ) (2,691 ) Tax rate reduction impact 0 (8,191 ) 0 Basis reduction on historic tax credit 0 4,599 0 Tax benefit of equity compensation (565 ) (1,449 ) (72 ) State income taxes, net of federal tax benefit 2,070 932 741 Affordable housing investments 4,725 2,798 1,923 Other 348 263 (541 ) Income tax expense $ 41,626 $ 19,376 $ 42,205
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	The major components of the temporary differences that gave rise to deferred tax assets and liabilities at December 31, 2018 , and 2017 , were as follows: (Dollars in thousands) 2018 2017 Deferred tax assets Allowance for loan and lease losses $ 12,782 $ 12,134 Fair value adjustments on business combinations 11,199 369 Deferred compensation 392 384 Postretirement benefits other than pension liability 676 564 Accrued stock-based compensation 1,145 932 OREO write-downs 118 97 Interest on nonaccrual loans 1,160 616 Accrued expenses 5,808 3,051 Net unrealized losses on investment securities and derivatives 3,221 249 State net operating loss 3,119 0 Federal tax credit carryforwards 873 0 Other 425 339 Total deferred tax assets 40,918 18,735 Deferred tax liabilities Tax depreciation in excess of book depreciation (9,530 ) (2,510 ) FHLB and FRB stock (4,044 ) (3,384 ) Mortgage-servicing rights (2,285 ) (343 ) Leasing activities (3,881 ) (2,792 ) Retirement obligation (6,614 ) (8,888 ) Intangible assets (12,310 ) (11,559 ) Deferred loan fees and costs (131 ) (371 ) Prepaid expenses (582 ) (210 ) Limited partnership investments (2,367 ) (1,230 ) Other (1,867 ) (2,415 ) Total deferred tax liabilities (43,611 ) (33,702 ) Total net deferred tax liability $ (2,693 ) $ (14,967 )
Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table Text Block]	A progression of unrecognized tax benefits as of December 31, 2018 and 2017 is as follows: (Dollars in thousands) 2018 2017 Balance at beginning of year $ 3,735 $ 3,735 Additions for tax positions of prior years 0 0 Balance at end of year $ 3,735 $ 3,735

EMPLOYEE BENEFIT PLANS (Tables)

EMPLOYEE BENEFIT PLANS (Tables)	12 Months Ended
EMPLOYEE BENEFIT PLANS (Tables)	Dec. 31, 2018
Schedule of Amounts Recognized in Balance Sheet and Income Statement [Table Text Block]	The following tables set forth information concerning amounts recognized in First Financial's Consolidated Balance Sheets and Consolidated Statements of Income related to the Company's pension plan: December 31, (Dollars in thousands) 2018 2017 Change in benefit obligation Benefit obligation at beginning of year $ 71,154 $ 62,729 Service cost 6,501 4,894 Interest cost 2,394 2,325 Actuarial (gain) loss (4,032 ) 6,107 Benefits paid, excluding settlement (7,731 ) (4,901 ) Benefit obligation at end of year 68,286 71,154 Change in plan assets Fair value of plan assets at beginning of year 144,349 131,011 Actual return on plan assets (6,540 ) 18,239 Benefits paid, excluding settlement (7,731 ) (4,901 ) Fair value of plan assets at end of year 130,078 144,349 Amounts recognized in the Consolidated Balance Sheets Assets 61,792 73,195 Liabilities 0 0 Net amount recognized $ 61,792 $ 73,195 Amounts recognized in accumulated other comprehensive income (loss) Net actuarial loss $ 43,711 $ 33,580 Net prior service cost (1,508 ) (1,921 ) Deferred tax assets (9,613 ) (12,028 ) Net amount recognized $ 32,590 $ 19,631 Change in accumulated other comprehensive income (loss) $ 12,959 $ (3,172 ) Accumulated benefit obligation $ 66,320 $ 69,678
Schedule of Components of Net Periodic Benefit Cost [Table Text Block]	Components of net periodic benefit cost December 31, (Dollars in thousands) 2018 2017 2016 Service cost $ 6,501 $ 4,894 $ 5,034 Interest cost 2,394 2,325 2,262 Expected return on assets (9,811 ) (9,358 ) (9,644 ) Amortization of prior service cost (413 ) (413 ) (413 ) Recognized net actuarial loss 2,188 1,924 1,608 Net periodic benefit (income) cost 859 (628 ) (1,153 ) Other changes recognized in accumulated other comprehensive income (loss) Net actuarial (gain) loss 12,319 (2,775 ) (884 ) Prior service cost 0 0 0 Amortization of prior service cost 413 413 413 Amortization of gain (2,188 ) (1,924 ) (1,608 ) Total recognized in accumulated other comprehensive income (loss) 10,544 (4,286 ) (2,079 ) Total recognized in net periodic benefit cost and accumulated other comprehensive income (loss) $ 11,403 $ (4,914 ) $ (3,232 ) Amount expected to be recognized in net periodic pension expense in the coming year Amortization of (gain) loss $ 1,867 $ 2,090 $ 1,754 Amortization of prior service credit (413 ) (413 ) (413 )
Schedule of Assumptions Used [Table Text Block]	Pension plan assumptions December 31, 2018 2017 2016 Benefit obligations Discount rate 4.31 % 3.43 % 3.88 % Rate of compensation increase 3.50 % 3.50 % 3.50 % Net periodic benefit cost Discount rate 3.43 % 3.88 % 4.05 % Expected return on plan assets 7.25 % 7.25 % 7.50 % Rate of compensation increase 3.50 % 3.50 % 3.50 %
Schedule of Changes in Fair Value of Plan Assets [Table Text Block]	The fair value of the plan assets as of December 31, 2018 by asset category is shown in the table that follows: Fair Value Measurements (Dollars in thousands) Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Asset Category Cash $ 216 $ 216 $ 0 $ 0 U. S. Government agencies 8,053 0 8,053 0 Fixed income mutual funds 74,453 74,453 0 0 Equity mutual funds 47,356 47,356 0 0 Total $ 130,078 $ 122,025 $ 8,053 $ 0 The fair value of the plan assets as of December 31, 2017 by asset category is shown in the table that follows: Fair Value Measurements (Dollars in thousands) Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Asset Category Cash $ 175 $ 175 $ 0 $ 0 U. S. Government agencies 6,853 0 6,853 0 Fixed income mutual funds 69,154 69,154 0 0 Equity mutual funds 68,167 68,167 0 0 Total $ 144,349 $ 137,496 $ 6,853 $ 0
Schedule of Expected Benefit Payments [Table Text Block]	The following benefit payments, which reflect expected future service, are expected to be paid: (Dollars in thousands) 2019 $ 4,396 2020 5,280 2021 5,229 2022 4,739 2023 4,917 Thereafter 29,948

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	12 Months Ended
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	Dec. 31, 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 accumulated other comprehensive income (loss) are as follows: December 31, 2018 Total other comprehensive income (loss) Total accumulated (Dollars in thousands) Prior to Reclass Pre-tax Tax effect Net of tax Beginning balance Net activity Cumulative effect of new standard Ending balance Unrealized gain (loss) on debt securities $ (14,461 ) $ (161 ) $ (14,300 ) $ 3,071 $ (11,229 ) $ (182 ) $ (11,229 ) $ (190 ) $ (11,601 ) Unrealized gain (loss) on derivatives 628 0 628 (144 ) 484 (577 ) 484 (124 ) (217 ) Retirement obligation (12,319 ) (1,775 ) (10,544 ) 2,364 (8,180 ) (19,631 ) (8,180 ) (4,779 ) (32,590 ) Total $ (26,152 ) $ (1,936 ) $ (24,216 ) $ 5,291 $ (18,925 ) $ (20,390 ) $ (18,925 ) $ (5,093 ) $ (44,408 ) December 31, 2017 Total other comprehensive income (loss) Total accumulated other (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 $ 8,447 $ 1,649 $ 6,798 $ (2,431 ) $ 4,367 $ (4,549 ) $ 4,367 $ (182 ) Unrealized gain (loss) on derivatives 810 0 810 (296 ) 514 (1,091 ) 514 (577 ) Retirement obligation 2,775 (1,511 ) 4,286 (1,114 ) 3,172 (22,803 ) 3,172 (19,631 ) Total $ 12,032 $ 138 $ 11,894 $ (3,841 ) $ 8,053 $ (28,443 ) $ 8,053 $ (20,390 ) December 31, 2016 Total other comprehensive income (loss) 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 $ 751 $ 234 $ 517 $ (133 ) $ 384 $ (4,933 ) $ 384 $ (4,549 ) Unrealized gain (loss) on derivatives 809 0 809 (301 ) 508 (1,599 ) 508 (1,091 ) Retirement obligation 884 (1,195 ) 2,079 (834 ) 1,245 (24,048 ) 1,245 (22,803 ) Total $ 2,444 $ (961 ) $ 3,405 $ (1,268 ) $ 2,137 $ (30,580 ) $ 2,137 $ (28,443 )
Other Accumulated Comprehensive income reclassified from AOCI [Table Text Block]	The following table details the activity reclassified from accumulated other comprehensive income into income during the period: Amount Reclassified from Accumulated Other Comprehensive Income (1) December 31, (Dollars in thousands) 2018 2017 2016 Affected Line Item in the Consolidated Statements of Income Realized gains and losses on securities available-for-sale $ (161 ) $ 1,649 $ 234 Net gain (loss) on sales of investment securities Defined benefit pension plan Amortization of prior service cost (2) 413 413 413 Other noninterest expense Recognized net actuarial loss (2) (2,188 ) (1,924 ) (1,608 ) Other noninterest expense Amortization and settlement charges of defined benefit pension items (1,775 ) (1,511 ) (1,195 ) Total reclassifications for the period, before tax $ (1,936 ) $ 138 $ (961 ) (1) Negative amounts are debits to profit/loss. (2) Included in the computation of net periodic pension cost (see Note 15 - Employee Benefit Plans for additional details).

CAPITAL (Tables)

CAPITAL (Tables)	12 Months Ended
CAPITAL (Tables)	Dec. 31, 2018
Banking and Thrift [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block]	Actual Minimum capital Required to be Minimum capital (Dollars in thousands) Capital Ratio Capital Ratio Capital Ratio Capital Ratio December 31, 2018 Common equity tier 1 capital to risk-weighted assets Consolidated $ 1,215,613 11.87 % $ 652,874 6.375 % N/A N/A $ 716,881 7.00 % First Financial Bank 1,279,492 12.50 % 652,590 6.375 % $ 665,386 6.50 % 716,570 7.00 % Tier 1 capital to risk-weighted assets Consolidated 1,257,366 12.28 % 806,491 7.875 % N/A N/A 870,499 8.50 % First Financial Bank 1,279,596 12.50 % 806,141 7.875 % $ 818,937 8.00 % 870,120 8.50 % Total capital to risk-weighted assets Consolidated 1,444,146 14.10 % 1,011,314 9.875 % N/A N/A 1,075,322 10.50 % First Financial Bank 1,344,388 13.13 % 1,010,875 9.875 % 1,023,671 10.00 % 1,074,855 10.50 % Leverage Consolidated 1,257,366 9.71 % 517,958 4.00 % N/A N/A 517,958 4.00 % First Financial Bank 1,279,596 9.89 % 517,710 4.00 % 647,138 5.00 % 517,710 4.00 % Actual Minimum capital Required to be Minimum capital (Dollars in thousands) Capital Ratio Capital Ratio Capital Ratio Capital Ratio December 31, 2017 Common equity tier 1 capital to risk-weighted assets Consolidated $ 755,735 10.63 % $ 408,746 5.75 % N/A N/A $ 497,604 7.00 % First Financial Bank 794,251 11.21 % 407,220 5.75 % $ 460,336 6.50 % 495,746 7.00 % Tier 1 capital to risk-weighted assets Consolidated 755,839 10.63 % 515,376 7.25 % N/A N/A 604,233 8.50 % First Financial Bank 794,355 11.22 % 513,452 7.25 % 566,567 8.00 % 601,978 8.50 % Total capital to risk-weighted assets Consolidated 929,148 13.07 % 657,548 9.25 % N/A N/A 746,406 10.50 % First Financial Bank 856,363 12.09 % 655,093 9.25 % 708,209 10.00 % 743,619 10.50 % Leverage Consolidated 755,839 8.84 % 342,198 4.00 % N/A N/A 342,198 4.00 % First Financial Bank 794,355 9.29 % 342,113 4.00 % 427,642 5.00 % 342,113 4.00 %

STOCK OPTIONS AND AWARDS (Table

STOCK OPTIONS AND AWARDS (Tables)	12 Months Ended
STOCK OPTIONS AND AWARDS (Tables)	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based Compensation, Stock Options, Activity [Table Text Block]	Stock option activity for the year ended December 31, 2018 , is summarized as follows: (Dollars in thousands, except share and per share data) Number of shares Weighted average exercise price Weighted average remaining contractual life Aggregate intrinsic value Outstanding at beginning of year 11,800 $ 11.64 Granted 0 0.00 Assumed 83,551 8.54 Exercised (32,941 ) 8.62 Forfeited or expired 0 0.00 Outstanding at end of year 62,410 $ 9.08 3.72 $ 914 Exercisable at end of year 62,410 $ 9.08 3.72 $ 914
Schedule of Cash Proceeds Received from Share-based Payment Awards [Table Text Block] (Deprecated 2017-01-31)	2018 2017 2016 Total intrinsic value of options exercised $ 734 $ 1,533 $ 661 Cash received from exercises $ 284 $ 341 $ 801 Tax benefit from exercises $ 1,439 $ 1,991 $ 1,958
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]	Activity in restricted stock for the previous three years ended December 31 is summarized as follows: 2018 2017 2016 Number of shares Weighted average grant date fair value Number of shares Weighted average grant date fair value Number of shares Weighted average grant date fair value Nonvested at beginning of year 468,372 $ 21.63 648,817 $ 17.82 643,641 $ 17.21 Granted 303,930 28.94 234,529 27.36 317,695 18.13 Vested (267,031 ) 20.94 (307,825 ) 18.12 (263,713 ) 16.82 Forfeited (42,825 ) 26.38 (107,149 ) 21.18 (48,806 ) 17.37 Nonvested at end of year 462,446 $ 26.39 468,372 $ 21.63 648,817 $ 17.82

EARNINGS PER COMMON SHARE (Tabl

EARNINGS PER COMMON SHARE (Tables)	12 Months Ended
EARNINGS PER COMMON SHARE (Tables)	Dec. 31, 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: (Dollars in thousands, except share and per share data) 2018 2017 2016 Numerator Net income $ 172,595 $ 96,787 $ 88,526 Denominator Basic earnings per common share - weighted average shares 88,582,090 61,529,460 61,206,093 Effect of dilutive securities Employee stock awards 514,680 581,329 729,335 Warrants 517,435 60,801 49,994 Diluted earnings per common share - adjusted weighted average shares 89,614,205 62,171,590 61,985,422 Earnings per share available to common shareholders Basic $ 1.95 $ 1.57 $ 1.45 Diluted $ 1.93 $ 1.56 $ 1.43

FAIR VALUE DISCLOSURES (Tables)

FAIR VALUE DISCLOSURES (Tables)	12 Months Ended
FAIR VALUE DISCLOSURES (Tables)	Dec. 31, 2018
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 December 31, 2018 Financial assets Cash and short-term investments $ 273,959 $ 273,959 $ 273,959 $ 0 $ 0 Investment securities held-to-maturity 429,328 424,118 0 424,118 0 Other investments 115,660 N/A N/A N/A N/A Loans held for sale 4,372 4,372 0 4,372 0 Loans and leases, net of ALLL 8,767,672 8,662,868 0 0 8,662,868 Accrued interest receivable 41,816 41,816 0 13,819 27,997 Financial liabilities Deposits Noninterest-bearing $ 2,492,434 $ 2,492,434 $ 0 $ 2,492,434 $ 0 Interest-bearing demand 2,307,071 2,307,071 0 2,307,071 0 Savings 3,167,325 3,167,325 0 3,167,325 0 Time 2,173,564 2,146,645 0 2,146,645 0 Total deposits 10,140,394 10,113,475 0 10,113,475 0 Short-term borrowings 1,040,691 1,040,691 1,040,691 0 0 Long-term debt 570,739 557,933 0 557,933 0 Accrued interest payable 12,126 12,126 2,035 10,091 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, net of ALLL 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 Noninterest-bearing $ 1,662,058 $ 1,662,058 $ 0 $ 1,662,058 $ 0 Interest-bearing demand 1,453,463 1,453,463 0 1,453,463 0 Savings 2,462,420 2,462,420 0 2,462,420 0 Time 1,317,105 1,306,674 0 1,306,674 0 Total 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 Assets/Liabilities (Dollars in thousands) Level 1 Level 2 Level 3 at Fair Value December 31, 2018 Assets Derivatives $ 0 $ 29,543 $ 0 $ 29,543 Investment securities available-for-sale 97 2,779,158 0 2,779,255 Total $ 97 $ 2,808,701 $ 0 $ 2,808,798 Liabilities Derivatives $ 0 $ 29,336 $ 0 $ 29,336 Fair Value Measurements Using Assets/Liabilities (Dollars in thousands) Level 1 Level 2 Level 3 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 December 31, 2018 Assets Impaired loans $ 0 $ 0 $ 1,320 OREO 0 0 1,089 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)	12 Months Ended
BUSINESS COMBINATIONS (Tables)	Dec. 31, 2018
Business Acquisition [Line Items]
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 1,043,424 Warrant consideration 14,460 Options consideration 1,577 Total purchase consideration 1,059,504 Assets acquired Cash 71,688 Investment securities available-for-sale 900,935 Investment securities held-to-maturity 171,423 Other investments 28,763 Loans 2,792,740 Premises and equipment 98,381 Intangible assets 42,887 Other assets 167,693 Assets held for sale 127,775 Total assets acquired 4,402,285 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 383,337 Goodwill $ 676,167
Business Acquisition, Pro Forma Information, Nonrecurring Adjustments	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. Twelve months ended December 31, (Dollars in thousands, except per share data) (Unaudited) 2018 2017 Pro Forma Condensed Combined Income Statement Information Net interest income $ 484,915 $ 454,579 Net income 221,122 130,402 Basic earnings per share $ 2.27 $ 1.34 Diluted earnings per share $ 2.25 $ 1.33

FIRST FINANCIAL BANCORP. (PAR_2

FIRST FINANCIAL BANCORP. (PARENT COMPANY ONLY) FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Schedule of Condensed Balance Sheet	Balance Sheets December 31, (Dollars in thousands) 2018 2017 Assets Cash $ 86,878 $ 57,719 Investment securities, available for sale 694 442 Subordinated notes from subsidiaries 7,500 7,500 Investment in subsidiaries Commercial banks 2,078,655 970,290 Nonbanks 7,194 0 Total investment in subsidiaries 2,085,849 970,290 Premises and equipment 1,361 1,378 Other assets 71,817 26,778 Total assets $ 2,254,099 $ 1,064,107 Liabilities Subordinated debentures $ 171,416 $ 118,638 Dividends payable 465 10,965 Other liabilities 3,969 3,840 Total liabilities 175,850 133,443 Shareholders’ equity 2,078,249 930,664 Total liabilities and shareholders’ equity $ 2,254,099 $ 1,064,107
Schedule of Condensed Income Statement	Statements of Income and Comprehensive Income Years Ended December 31, (Dollars in thousands) 2018 2017 2016 Income Interest income $ 23 $ 6 $ 48 Noninterest income 0 86 2,596 Dividends from subsidiaries 107,340 54,600 52,700 Total income 107,363 54,692 55,344 Expenses Interest expense 8,798 6,152 6,151 Salaries and employee benefits 6,413 5,519 5,445 Miscellaneous professional services 5,130 970 711 Other 5,648 4,819 4,841 Total expenses 25,989 17,460 17,148 Income before income taxes and equity in undistributed net earnings of subsidiaries 81,374 37,232 38,196 Income tax expense (benefit) (6,687 ) (7,080 ) (5,302 ) Equity in undistributed earnings (loss) of subsidiaries 84,534 52,475 45,028 Net income $ 172,595 $ 96,787 $ 88,526 Comprehensive income $ 153,670 $ 104,840 $ 90,663
Schedule of Condensed Cash Flow Statement	Statements of Cash Flows Years Ended December 31, (Dollars in thousands) 2018 2017 2016 Operating activities Net income $ 172,595 $ 96,787 $ 88,526 Adjustments to reconcile net income to net cash provided by operating activities Equity in undistributed (earnings) loss of subsidiaries (84,534 ) (52,475 ) (45,028 ) Depreciation and amortization 194 193 192 Stock-based compensation expense 6,219 5,446 5,354 Deferred income taxes 739 (360 ) 584 (Decrease) increase in dividends payable (10,500 ) 579 135 Increase (decrease) in other liabilities 9,979 (889 ) (389 ) Decrease (increase) in other assets 16,346 (6,951 ) (9,065 ) Net cash provided by (used in) operating activities 111,038 42,330 40,309 Investing activities Capital contributions to subsidiaries (3,000 ) 0 (53,000 ) Net cash acquired (paid) from business combinations 11,353 0 0 Proceeds from calls and maturities of investment securities 0 0 5,978 Purchases of investment securities 0 0 (333 ) Net cash (used in) provided by investing activities 8,353 0 (47,355 ) Financing activities (Decrease) increase in short-term borrowings (8,333 ) 0 0 Cash dividends paid on common stock (79,655 ) (41,178 ) (39,125 ) Proceeds from exercise of stock options, net of shares purchased 284 341 801 Excess tax benefit on share-based compensation 0 0 264 Other (2,528 ) (3,059 ) (1,681 ) Net cash (used in) provided by financing activities (90,232 ) (43,896 ) (39,741 ) Net increase (decrease) in cash 29,159 (1,566 ) (46,787 ) Cash at beginning of year 57,719 59,285 106,072 Cash at end of year $ 86,878 $ 57,719 $ 59,285

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	12 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	Dec. 31, 2018USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance threshold for impaired and non-impaired commercial loans	$ 250,000
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

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Premises and Equipment (Details)	12 Months Ended
	Dec. 31, 2018
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Minimum \| Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Minimum \| Furniture, Fixtures, and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Minimum \| Software, Hardware, and Data Handling Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Maximum \| Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Maximum \| Furniture, Fixtures, and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Maximum \| Software, Hardware, and Data Handling Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years

RECENTLY ADOPTED AND ISSUED A_2

RECENTLY ADOPTED AND ISSUED ACCOUNTING STANDARDS RECENTLY ADOPTED AND ISSUED ACCOUNTING STANDARDS - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Recently Adopted and Issued Accounting Standards [Abstract]
Unrealized gain (loss) on debt securities	$ (190)
Operating Lease, Right-of-Use Asset	62,500
Operating Lease, Liability	68,100
Reclassification from AOCI, Current Period, Tax	$ 4,900

RESTRICTIONS ON CASH AND DIVI_2

RESTRICTIONS ON CASH AND DIVIDENDS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Restrictions on Subsidiary Dividends, Loans or Advances [Line Items]
Average Restriction on Cash and Due From Bank Accounts	$ 85.9	$ 66.7
Subsidiaries [Member]
Restrictions on Subsidiary Dividends, Loans or Advances [Line Items]
Retained Earnings, Unappropriated	637.2
Amount Available for Dividend Distribution without Affecting Capital Adequacy Requirements	$ 181.3

INVESTMENT SECURITIES INVESTMEN

INVESTMENT SECURITIES INVESTMENTS - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Gain (Loss) on Securities [Line Items]
Proceeds from Sale of Debt Securities, Available-for-sale	$ 290,700	$ 190,000	$ 207,000
Available-for-sale Securities, Gross Realized Gains	500	1,800	1,200
Available-for-sale Securities, Gross Realized Losses	600	200	1,000
Available For Sale Securities Net Realized Gain Loss Tax Provision	0	600	100
Securities transferred from AFS to HTM	372,128	0	0
Proceeds from Sale of Held-to-maturity Securities	0	0	$ 4,862
Pledged Financial Instruments, Not Separately Reported, Securities	$ 1,200,000	$ 800,000
NumberOfSecuritiesInSecurityPortfolio	1,417	775
NumberOfSecuritiesInUnrealizedLossPosition	504	237

INVESTMENTS - Summary of Held-T

INVESTMENTS - Summary of Held-To-Maturity and Available-For-Sale Investment Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Amortized cost	$ 429,328	$ 654,008
Held To Maturity Gross Unrealized Gain Accumulated In Investments	2,212	5,572
Held To Maturity Securities Gross Unrealized Loss Accumulated In Investments	7,422	6,479
Held-to-Maturity Market Value	424,118	653,101
Amortized Cost	2,792,326	1,348,227
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	9,409	8,328
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	22,480	7,147
Investment securities, available for sale	2,779,255	1,349,408
Pledged Financial Instruments, Not Separately Reported, Securities	1,200,000	800,000
U.S. Treasuries
Investment Holdings [Line Items]
Amortized cost	0	0
Held To Maturity Gross Unrealized Gain Accumulated In Investments	0	0
Held To Maturity Securities Gross Unrealized Loss Accumulated In Investments	0	0
Held-to-Maturity Market Value	0	0
Amortized Cost	99	98
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	0	0
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	2	1
Investment securities, available for sale	97	97
Securities of U.S. government agencies and corporations
Investment Holdings [Line Items]
Amortized cost	0	11,168
Held To Maturity Gross Unrealized Gain Accumulated In Investments	0	0
Held To Maturity Securities Gross Unrealized Loss Accumulated In Investments	0	76
Held-to-Maturity Market Value	0	11,092
Amortized Cost	32,095	15,695
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	57	220
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	233	0
Investment securities, available for sale	31,919	15,915
Residential Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Amortized cost	25,565	162,093
Held To Maturity Gross Unrealized Gain Accumulated In Investments	0	2,042
Held To Maturity Securities Gross Unrealized Loss Accumulated In Investments	1,045	1,535
Held-to-Maturity Market Value	24,520	162,600
Amortized Cost	565,071	290,793
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	691	849
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	7,163	2,599
Investment securities, available for sale	558,599	289,043
Commercial Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Amortized cost	147,780	255,027
Held To Maturity Gross Unrealized Gain Accumulated In Investments	258	1,372
Held To Maturity Securities Gross Unrealized Loss Accumulated In Investments	4,385	3,000
Held-to-Maturity Market Value	143,653	253,399
Amortized Cost	423,797	150,356
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	819	164
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	3,581	1,417
Investment securities, available for sale	421,035	149,103
Collateralized Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Amortized cost	12,540	143,545
Held To Maturity Gross Unrealized Gain Accumulated In Investments	0	354
Held To Maturity Securities Gross Unrealized Loss Accumulated In Investments	633	1,602
Held-to-Maturity Market Value	11,907	142,297
Amortized Cost	928,586	306,095
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	4,319	1,158
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	6,158	1,861
Investment securities, available for sale	926,747	305,392
Obligations of state and other political subdivisions
Investment Holdings [Line Items]
Amortized cost	243,443	82,175
Held To Maturity Gross Unrealized Gain Accumulated In Investments	1,954	1,804
Held To Maturity Securities Gross Unrealized Loss Accumulated In Investments	1,359	266
Held-to-Maturity Market Value	244,038	83,713
Amortized Cost	257,300	124,269
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	2,554	2,162
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	1,429	676
Investment securities, available for sale	258,425	125,755
Asset-backed Securities [Member]
Investment Holdings [Line Items]
Amortized cost	0	0
Held To Maturity Gross Unrealized Gain Accumulated In Investments	0	0
Held To Maturity Securities Gross Unrealized Loss Accumulated In Investments	0	0
Held-to-Maturity Market Value	0	0
Amortized Cost	511,430	377,655
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	611	1,628
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	2,810	306
Investment securities, available for sale	509,231	378,977
Other securities
Investment Holdings [Line Items]
Amortized cost	0	0
Held To Maturity Gross Unrealized Gain Accumulated In Investments	0	0
Held To Maturity Securities Gross Unrealized Loss Accumulated In Investments	0	0
Held-to-Maturity Market Value	0	0
Amortized Cost	73,948	83,266
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	358	2,147
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	1,104	287
Investment securities, available for sale	$ 73,202	$ 85,126

INVESTMENTS - Summary of Invest

INVESTMENTS - Summary of Investment Securities by Estimated Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Held-to-Maturity Amortized Cost
Amortized cost	$ 429,328	$ 654,008
Held-to-Maturity Market Value
Held-to-Maturity Market Value	424,118	653,101
Available-for-Sale Amortized Cost
Amortized Cost	2,792,326	1,348,227
Available-for-Sale Market Value
Investment securities, available for sale	2,779,255	1,349,408
One Year or Less [Member]
Held-to-Maturity Amortized Cost
Amortized cost	0
Held-to-Maturity Market Value
Held-to-Maturity Market Value	0
Available-for-Sale Amortized Cost
Amortized Cost	5,972
Available-for-Sale Market Value
Investment securities, available for sale	5,977
After One Year Through Five Years [Member]
Held-to-Maturity Amortized Cost
Amortized cost	275
Held-to-Maturity Market Value
Held-to-Maturity Market Value	279
Available-for-Sale Amortized Cost
Amortized Cost	63,995
Available-for-Sale Market Value
Investment securities, available for sale	64,040
After Five Years Through Ten Years [Member]
Held-to-Maturity Amortized Cost
Amortized cost	21,110
Held-to-Maturity Market Value
Held-to-Maturity Market Value	21,374
Available-for-Sale Amortized Cost
Amortized Cost	133,360
Available-for-Sale Market Value
Investment securities, available for sale	133,594
After Ten Years [Member]
Held-to-Maturity Amortized Cost
Amortized cost	222,058
Held-to-Maturity Market Value
Held-to-Maturity Market Value	222,385
Available-for-Sale Amortized Cost
Amortized Cost	160,115
Available-for-Sale Market Value
Investment securities, available for sale	160,032
Collateralized Mortgage Backed Securities [Member]
Held-to-Maturity Amortized Cost
Amortized cost	12,540	143,545
Held-to-Maturity Market Value
Held-to-Maturity Market Value	11,907	142,297
Available-for-Sale Amortized Cost
Amortized Cost	928,586	306,095
Available-for-Sale Market Value
Investment securities, available for sale	926,747	305,392
Asset-backed Securities [Member]
Held-to-Maturity Amortized Cost
Amortized cost	0	0
Held-to-Maturity Market Value
Held-to-Maturity Market Value	0	0
Available-for-Sale Amortized Cost
Amortized Cost	511,430	377,655
Available-for-Sale Market Value
Investment securities, available for sale	$ 509,231	$ 378,977

INVESTMENTS - Age of Gross Unre

INVESTMENTS - Age of Gross Unrealized Losses and Associated Fair Value by Investment Category (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments, Unrealized Loss Position [Line Items]
Proceeds from Sale of Held-to-maturity Securities	$ 0	$ 0	$ 4,862
Less than 12 Months Fair Value	961,572	570,095
Less than 12 Months Unrealized Loss	(6,345)	(4,745)
12 Months or More Fair Value	882,865	335,516
12 Months or More Unrealized Loss	(23,557)	(8,881)
Total Fair Value	1,844,437	905,611
Total Unrealized Loss	(29,902)	(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	97	0
12 Months or More Unrealized Loss	(2)	0
Total Fair Value	97	97
Total Unrealized Loss	(2)	(1)
Securities of U.S. government agencies and corporations
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	0	11,092
Less than 12 Months Unrealized Loss	0	(76)
12 Months or More Fair Value	16,777	0
12 Months or More Unrealized Loss	(233)	0
Total Fair Value	16,777	11,092
Total Unrealized Loss	(233)	(76)
Residential Mortgage Backed Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	186,029	175,183
Less than 12 Months Unrealized Loss	(935)	(1,109)
12 Months or More Fair Value	264,795	108,782
12 Months or More Unrealized Loss	(7,273)	(3,025)
Total Fair Value	450,824	283,965
Total Unrealized Loss	(8,208)	(4,134)
Commercial Mortgage Backed Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	147,754	132,818
Less than 12 Months Unrealized Loss	(369)	(1,713)
12 Months or More Fair Value	232,363	72,139
12 Months or More Unrealized Loss	(7,597)	(2,704)
Total Fair Value	380,117	204,957
Total Unrealized Loss	(7,966)	(4,417)
Collateralized Mortgage Backed Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	194,795	164,909
Less than 12 Months Unrealized Loss	(1,546)	(1,138)
12 Months or More Fair Value	240,514	101,436
12 Months or More Unrealized Loss	(5,245)	(2,325)
Total Fair Value	435,309	266,345
Total Unrealized Loss	(6,791)	(3,463)
Obligations of state and other political subdivisions
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	62,805	38,450
Less than 12 Months Unrealized Loss	(299)	(507)
12 Months or More Fair Value	86,644	21,639
12 Months or More Unrealized Loss	(2,489)	(435)
Total Fair Value	149,449	60,089
Total Unrealized Loss	(2,788)	(942)
Asset-backed Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	336,437	44,941
Less than 12 Months Unrealized Loss	(2,312)	(200)
12 Months or More Fair Value	37,105	24,396
12 Months or More Unrealized Loss	(498)	(106)
Total Fair Value	373,542	69,337
Total Unrealized Loss	(2,810)	(306)
Other securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	33,752	2,605
Less than 12 Months Unrealized Loss	(884)	(1)
12 Months or More Fair Value	4,570	7,124
12 Months or More Unrealized Loss	(220)	(286)
Total Fair Value	38,322	9,729
Total Unrealized Loss	$ (1,104)	$ (287)

LOANS - Additional Information

LOANS - Additional Information (Detail)	12 Months Ended
LOANS - Additional Information (Detail)	Dec. 31, 2018USD ($)loans	Dec. 31, 2017USD ($)loans	Dec. 31, 2016USD ($)loans	Dec. 31, 2015USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Restructured Loans \| loans	196	214	247
Total restructured loans	$ 38,500,000	$ 23,900,000	$ 35,400,000
Restructured Loans, Accrual Status	16,109,000	17,545,000	30,240,000
Restructured Loans, Nonaccrual Status	22,400,000	6,400,000	5,100,000
Loans and Leases Receivable, Impaired, Commitment to Lend	0		900,000
Restructured Loans, Allowance for Loan and Lease Losses Included in Reserves	1,500,000	1,300,000	1,900,000
Restructured Loans, Portion Determined to be Uncollectible	900,000	300,000	500,000
Accruing TDRs performing in accordance with restructured terms for more than one year	7,900,000	17,200,000	22,600,000
Purchased impaired loans, carrying balance	96,320,000	104,960,000
Gain (loss) on sale of other real estate owned	(373,000)	(642,000)	1,212,000
Real Estate Acquired Through Foreclosure	1,401,000	$ 2,781,000	$ 6,284,000	$ 13,254,000
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured Loans, Loan Relationships, Review Threshold Amount Minimum	$ 250,000

LOANS - Commercial and Consumer

LOANS - Commercial and Consumer Credit Exposure by Risk Attribute (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Commercial & industrial	$ 2,514,661	$ 1,912,743
Real Estate - Construction	548,935	467,730
Real Estate - Commercial	3,754,681	2,490,091
Lease financing	93,415	89,347
Total Commercial	6,911,692	4,959,911
Pass
Financing Receivable, Recorded Investment [Line Items]
Commercial & industrial	2,432,834	1,882,464
Real Estate - Construction	548,323	467,687
Real Estate - Commercial	3,664,434	2,446,999
Lease financing	90,902	88,078
Total Commercial	6,736,493	4,885,228
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Commercial & industrial	24,594	6,226
Real Estate - Construction	603	0
Real Estate - Commercial	38,653	4,436
Lease financing	0	0
Total Commercial	63,850	10,662
Substandard
Financing Receivable, Recorded Investment [Line Items]
Commercial & industrial	57,233	24,053
Real Estate - Construction	9	43
Real Estate - Commercial	51,594	38,656
Lease financing	2,513	1,269
Total Commercial	111,349	64,021
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Commercial & industrial	0	0
Real Estate - Construction	0	0
Real Estate - Commercial	0	0
Lease financing	0	0
Total Commercial	0	0
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	955,646	471,391
Residential Real Estate [Member] \| Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	939,936	463,459
Residential Real Estate [Member] \| Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	15,710	7,932
Home Equity Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	817,282	493,604
Home Equity Loan [Member] \| Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	811,108	489,148
Home Equity Loan [Member] \| Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	6,174	4,456
Consumer Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	93,212	41,586
Consumer Loan [Member] \| Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	93,038	41,331
Consumer Loan [Member] \| Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	174	255
Credit card
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	46,382	46,691
Credit card \| Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	46,382	46,691
Credit card \| Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	0	0
Installment
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	1,912,522	1,053,272
Installment \| Performing
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	1,890,464	1,040,629
Installment \| Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, before Fees, Gross	$ 22,058	$ 12,643

LOANS - Loan Delinquency, inclu

LOANS - Loan Delinquency, including Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	$ 70,190	$ 27,942
Current	8,657,704	5,880,281
Loans and Leases Receivable, Gross	8,727,894	5,908,223
Purchased impaired loans, carrying balance	96,320	104,960
Total loans and leases	8,824,214	6,013,183
Greater than 90 days past due and still accruing	63	62
30 to 59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	37,266	6,896
60 to 89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	5,536	3,179
Greater than 90 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	27,388	17,867
Commercial & industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	20,833	7,490
Current	2,488,450	1,901,821
Loans and Leases Receivable, Gross	2,509,283	1,909,311
Purchased impaired loans, carrying balance	5,378	3,432
Total loans and leases	2,514,661	1,912,743
Greater than 90 days past due and still accruing	0	0
Commercial & industrial \| 30 to 59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	13,369	755
Commercial & industrial \| 60 to 89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	41	1,657
Commercial & industrial \| Greater than 90 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	7,423	5,078
Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	352	485
Current	93,063	88,862
Loans and Leases Receivable, Gross	93,415	89,347
Purchased impaired loans, carrying balance	0	0
Total loans and leases	93,415	89,347
Greater than 90 days past due and still accruing	0	0
Lease financing \| 30 to 59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	352	485
Lease financing \| 60 to 89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	0	0
Lease financing \| Greater than 90 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	0	0
Construction real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	0	234
Current	548,687	467,216
Loans and Leases Receivable, Gross	548,687	467,450
Purchased impaired loans, carrying balance	248	280
Total loans and leases	548,935	467,730
Greater than 90 days past due and still accruing	0	0
Construction real estate \| 30 to 59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	0	234
Construction real estate \| 60 to 89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	0	0
Construction real estate \| Greater than 90 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	0	0
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	20,081	10,694
Current	3,682,455	2,419,969
Loans and Leases Receivable, Gross	3,702,536	2,430,663
Purchased impaired loans, carrying balance	52,145	59,428
Total loans and leases	3,754,681	2,490,091
Greater than 90 days past due and still accruing	0	0
Commercial real estate \| 30 to 59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	6,279	1,716
Commercial real estate \| 60 to 89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	1,158	201
Commercial real estate \| Greater than 90 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	12,644	8,777
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	18,571	3,329
Current	902,404	430,500
Loans and Leases Receivable, Gross	920,975	433,829
Purchased impaired loans, carrying balance	34,671	37,562
Total loans and leases	955,646	471,391
Greater than 90 days past due and still accruing	0	0
Residential real estate \| 30 to 59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	11,060	526
Residential real estate \| 60 to 89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	2,976	811
Residential real estate \| Greater than 90 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	4,535	1,992
Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	9,051	4,863
Current	804,835	485,127
Loans and Leases Receivable, Gross	813,886	489,990
Purchased impaired loans, carrying balance	3,396	3,614
Total loans and leases	817,282	493,604
Greater than 90 days past due and still accruing	0	0
Home equity \| 30 to 59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	5,245	2,716
Home equity \| 60 to 89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	1,228	394
Home equity \| Greater than 90 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	2,578	1,753
Installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	602	413
Current	92,128	40,529
Loans and Leases Receivable, Gross	92,730	40,942
Purchased impaired loans, carrying balance	482	644
Total loans and leases	93,212	41,586
Greater than 90 days past due and still accruing	0	0
Installment \| 30 to 59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	420	179
Installment \| 60 to 89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	37	29
Installment \| Greater than 90 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	145	205
Credit card
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	700	434
Current	45,682	46,257
Loans and Leases Receivable, Gross	46,382	46,691
Purchased impaired loans, carrying balance	0	0
Total loans and leases	46,382	46,691
Greater than 90 days past due and still accruing	63	62
Credit card \| 30 to 59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	541	285
Credit card \| 60 to 89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	96	87
Credit card \| Greater than 90 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivables, Past Due	$ 63	$ 62

LOANS - Restructured Loans (Det

LOANS - Restructured Loans (Details)	12 Months Ended
LOANS - Restructured Loans (Details)	Dec. 31, 2018USD ($)loansd	Dec. 31, 2017USD ($)loans	Dec. 31, 2016USD ($)loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extended Maturities	$ 4,093,000	$ 3,261,000	$ 2,571,000
Adjusted Interest Rates	52,000	2,767,000	0
Combined Rate And Maturity	0	489,000	3,046,000
Forebearance Agreements	23,175,000	1,181,000	88,000
Other	985,000	75,000	3,507,000
Total	$ 28,305,000	$ 7,773,000	$ 9,212,000
Number of Restructured Loans \| loans	196	214	247
Restructured loans, Number of Loans \| loans	43	22	47
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 28,571,000	$ 7,995,000	$ 9,616,000
Restructured loans, Period End Balance	$ 28,305,000	$ 7,773,000	$ 9,212,000
Restructured loans with payment default within 12 months of modification, Number of Loans \| loans	1	1	4
Restructured loans with payment default within 12 months of modification, Period End Balance	$ 41,000	$ 1,500,000	$ 300,000
Total restructured loans	38,500,000	23,900,000	35,400,000
Restructured Loans, Accrual Status	16,109,000	17,545,000	30,240,000
Restructured Loans, Nonaccrual Status	22,400,000	6,400,000	5,100,000
Loans and Leases Receivable, Impaired, Commitment to Lend	0		900,000
Restructured Loans, Allowance for Loan and Lease Losses Included in Reserves	1,500,000	1,300,000	1,900,000
Accruing TDRs performing in accordance with restructured terms for more than one year	$ 7,900,000	$ 17,200,000	$ 22,600,000
Restructured loans performance threshold (days) \| d	90
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured Loans, Loan Relationships, Review Threshold Amount Minimum	$ 250,000
Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans \| loans	17	7	18
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 23,943,000	$ 5,724,000	$ 3,402,000
Restructured loans, Period End Balance	$ 23,890,000	$ 5,661,000	$ 3,508,000
Construction real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans \| loans	0	0	0
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 0	$ 0	$ 0
Restructured loans, Period End Balance	$ 0	$ 0	$ 0
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans \| loans	8	8	16
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 3,385,000	$ 1,816,000	$ 5,200,000
Restructured loans, Period End Balance	$ 3,150,000	$ 1,758,000	$ 4,752,000
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans \| loans	13	6	5
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 1,148,000	$ 416,000	$ 840,000
Restructured loans, Period End Balance	1,073,000	$ 315,000	$ 787,000
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	5	1	5
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 95,000	$ 39,000	$ 165,000
Restructured loans, Period End Balance	$ 192,000	$ 39,000	$ 156,000
Installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans \| loans	0	0	3
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 0	$ 0	$ 9,000
Restructured loans, Period End Balance	$ 0	$ 0	$ 9,000

LOANS - Nonaccrual, Restructure

LOANS - Nonaccrual, Restructured and Impaired Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Modifications [Line Items]
Nonaccrual loans	$ 70,700	$ 24,082	$ 17,730
Restructured loans - accrual status	16,109	17,545	30,240
Total impaired loans	86,809	41,627	47,970
Interest income effect
Gross amount of interest that would have been recorded under original terms	4,656	3,397	2,848
Interest included in income
Nonaccrual loans	715	535	375
Restructured loans	642	710	876
Impaired Financing Receivable, Interest Income, Accrual Method	1,357	1,245	1,251
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	3,299	2,152	1,597
Loans and Leases Receivable-Nonaccrual, future commitment to lend	200	0	0
Restructured loans - nonaccrual status	22,400	6,400	5,100
Commercial & industrial
Financing Receivable, Modifications [Line Items]
Nonaccrual loans	30,925	5,229	2,419
Total impaired loans	37,633	7,331
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	404	308	346
Lease financing
Financing Receivable, Modifications [Line Items]
Nonaccrual loans	22	82	195
Total impaired loans	22	82
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	0	4	11
Construction real estate
Financing Receivable, Modifications [Line Items]
Nonaccrual loans	9	29	0
Total impaired loans	9	29
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	2	1	0
Commercial real estate
Financing Receivable, Modifications [Line Items]
Nonaccrual loans	20,500	10,616	6,098
Total impaired loans	25,022	21,542
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	508	603	568
Residential real estate
Financing Receivable, Modifications [Line Items]
Nonaccrual loans	13,495	4,140	5,251
Total impaired loans	17,598	7,932
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	324	222	229
Home equity
Financing Receivable, Modifications [Line Items]
Nonaccrual loans	5,580	3,743	3,400
Total impaired loans	6,351	4,456
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	117	103	90
Installment
Financing Receivable, Modifications [Line Items]
Nonaccrual loans	169	243	367
Total impaired loans	174	255
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	$ 2	$ 4	$ 7

LOANS - Investment in Impaired

LOANS - Investment in Impaired Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Current balance	$ 86,809	$ 41,627	$ 47,970
Contractual Principal Balance	104,732	47,857
Allowance for loan and lease losses	1,160	779
Average Recorded Investment	59,728	51,846	51,548
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	1,269	1,147
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	88	98
Total interest included in income	1,357	1,245	1,251
Commercial & industrial
Financing Receivable, Impaired [Line Items]
Current balance	37,633	7,331
Contractual Principal Balance	43,500	8,629
Allowance for loan and lease losses	667	169
Average Recorded Investment	15,398	14,371	14,717
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	360	280
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	44	28	37
Total interest included in income	404	308	346
Lease financing
Financing Receivable, Impaired [Line Items]
Current balance	22	82
Contractual Principal Balance	22	82
Allowance for loan and lease losses	0	0
Average Recorded Investment	21	112	364
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	0	4
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	0	8
Total interest included in income	0	4	11
Construction real estate
Financing Receivable, Impaired [Line Items]
Current balance	9	29
Contractual Principal Balance	26	60
Allowance for loan and lease losses	0	0
Average Recorded Investment	20	601	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	2	1
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	0	0
Total interest included in income	2	1	0
Commercial real estate
Financing Receivable, Impaired [Line Items]
Current balance	25,022	21,542
Contractual Principal Balance	32,884	23,957
Allowance for loan and lease losses	461	448
Average Recorded Investment	26,140	23,569	22,044
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	490	563
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	18	40	211
Total interest included in income	508	603	568
Residential real estate
Financing Receivable, Impaired [Line Items]
Current balance	17,598	7,932
Contractual Principal Balance	20,276	9,208
Allowance for loan and lease losses	32	160
Average Recorded Investment	12,254	8,728	9,126
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	301	196
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	23	26	30
Total interest included in income	324	222	229
Home equity
Financing Receivable, Impaired [Line Items]
Current balance	6,351	4,456
Contractual Principal Balance	7,461	5,499
Allowance for loan and lease losses	0	2
Average Recorded Investment	5,621	4,133	4,931
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	114	99
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	3	4	4
Total interest included in income	117	103	90
Installment
Financing Receivable, Impaired [Line Items]
Current balance	174	255
Contractual Principal Balance	563	422
Allowance for loan and lease losses	0	0
Average Recorded Investment	274	332	366
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	2	4
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	0	0
Total interest included in income	2	4	7
Impaired Financing Receivables With Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Current balance	2,749	4,444
Contractual Principal Balance	2,749	4,452
Allowance for loan and lease losses	1,160	779
Average Recorded Investment	3,277	5,051	10,579
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method			290
Loans with no related allowance recorded [member]
Financing Receivable, Impaired [Line Items]
Current balance	84,060	37,183
Contractual Principal Balance	101,983	43,405
Allowance for loan and lease losses	0	0
Average Recorded Investment	56,451	46,795	40,969
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			961
Loans with no related allowance recorded [member] \| Commercial & industrial
Financing Receivable, Impaired [Line Items]
Current balance	36,694	7,162
Contractual Principal Balance	42,561	8,460
Allowance for loan and lease losses	0	0
Average Recorded Investment	14,498	13,167	13,619
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			309
Loans with no related allowance recorded [member] \| Lease financing
Financing Receivable, Impaired [Line Items]
Current balance	22	82
Contractual Principal Balance	22	82
Allowance for loan and lease losses	0	0
Average Recorded Investment	21	112	150
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			3
Loans with no related allowance recorded [member] \| Construction real estate
Financing Receivable, Impaired [Line Items]
Current balance	9	29
Contractual Principal Balance	26	60
Allowance for loan and lease losses	0	0
Average Recorded Investment	20	601	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			0
Loans with no related allowance recorded [member] \| Commercial real estate
Financing Receivable, Impaired [Line Items]
Current balance	23,513	18,423
Contractual Principal Balance	31,375	20,837
Allowance for loan and lease losses	0	0
Average Recorded Investment	24,738	20,935	14,252
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			357
Loans with no related allowance recorded [member] \| Residential real estate
Financing Receivable, Impaired [Line Items]
Current balance	17,297	6,876
Contractual Principal Balance	19,975	8,145
Allowance for loan and lease losses	0	0
Average Recorded Investment	11,359	7,616	7,752
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			199
Loans with no related allowance recorded [member] \| Home equity
Financing Receivable, Impaired [Line Items]
Current balance	6,351	4,356
Contractual Principal Balance	7,461	5,399
Allowance for loan and lease losses	0	0
Average Recorded Investment	5,541	4,032	4,830
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			86
Loans with no related allowance recorded [member] \| Installment
Financing Receivable, Impaired [Line Items]
Current balance	174	255
Contractual Principal Balance	563	422
Allowance for loan and lease losses	0	0
Average Recorded Investment	274	332	366
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			7
Impaired Financing Receivables With Related Allowance [Member] \| Commercial & industrial
Financing Receivable, Impaired [Line Items]
Current balance	939	169
Contractual Principal Balance	939	169
Allowance for loan and lease losses	667	169
Average Recorded Investment	900	1,204	1,098
Impaired Financing Receivables With Related Allowance [Member] \| Lease financing
Financing Receivable, Impaired [Line Items]
Current balance	0	0
Contractual Principal Balance	0	0
Allowance for loan and lease losses	0	0
Average Recorded Investment	0	0	214
Impaired Financing Receivables With Related Allowance [Member] \| Construction real estate
Financing Receivable, Impaired [Line Items]
Current balance	0	0
Contractual Principal Balance	0	0
Allowance for loan and lease losses	0	0
Average Recorded Investment	0	0	0
Impaired Financing Receivables With Related Allowance [Member] \| Commercial real estate
Financing Receivable, Impaired [Line Items]
Current balance	1,509	3,119
Contractual Principal Balance	1,509	3,120
Allowance for loan and lease losses	461	448
Average Recorded Investment	1,402	2,634	7,792
Impaired Financing Receivables With Related Allowance [Member] \| Residential real estate
Financing Receivable, Impaired [Line Items]
Current balance	301	1,056
Contractual Principal Balance	301	1,063
Allowance for loan and lease losses	32	160
Average Recorded Investment	895	1,112	1,374
Impaired Financing Receivables With Related Allowance [Member] \| Home equity
Financing Receivable, Impaired [Line Items]
Current balance	0	100
Contractual Principal Balance	0	100
Allowance for loan and lease losses	0	2
Average Recorded Investment	80	101	101
Impaired Financing Receivables With Related Allowance [Member] \| Installment
Financing Receivable, Impaired [Line Items]
Current balance	0	0
Contractual Principal Balance	0	0
Allowance for loan and lease losses	0	0
Average Recorded Investment	$ 0	$ 0	$ 0

LOANS - Changes in Other Real E

LOANS - Changes in Other Real Estate Owned (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of year	$ 2,781	$ 6,284	$ 13,254
Additions	3,182	4,119	2,872
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Cost of Investment in Real Estate Sold	3,797	6,983	9,356
Valuation adjustments	(765)	(639)	(486)
Balance at end of year	1,401	2,781	6,284
Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Additions	1,269	1,732	1,850
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Cost of Investment in Real Estate Sold	2,967	5,409	6,993
Valuation adjustments	(355)	(439)	(345)
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Additions	1,913	2,387	1,022
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Cost of Investment in Real Estate Sold	830	1,574	2,363
Valuation adjustments	$ (410)	$ (200)	$ (141)

ALLOWANCE FOR LOAN AND LEASE _3

ALLOWANCE FOR LOAN AND LEASE LOSSES - Changes in the Allowance for Loan and Lease Losses for the Previous Three Years (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for loan and lease losses
Balance at beginning of year	$ 54,021	$ 57,961	$ 53,398
Provision for loan and lease losses	14,586	3,582	10,140
Loans charged off	(20,670)	(13,663)	(11,114)
Recoveries	8,605	6,141	5,537
Allowance for Loan and Lease Losses Write-offs, Net	12,065	7,522	5,577
Commercial & industrial
Allowance for loan and lease losses
Balance at beginning of year	17,598	19,225	16,995
Provision for loan and lease losses	10,615	6,917	3,705
Loans charged off	(11,533)	(10,194)	(2,630)
Recoveries	2,066	1,650	1,155
Allowance for Loan and Lease Losses Write-offs, Net	9,467	8,544	1,475
Lease financing
Allowance for loan and lease losses
Balance at beginning of year	675	716	821
Provision for loan and lease losses	454	(42)	(106)
Loans charged off	0	0	0
Recoveries	1	1	1
Allowance for Loan and Lease Losses Write-offs, Net	(1)	(1)	(1)
Construction real estate
Allowance for loan and lease losses
Balance at beginning of year	3,577	3,282	1,810
Provision for loan and lease losses	(310)	207	1,280
Loans charged off	0	(1)	(93)
Recoveries	146	89	285
Allowance for Loan and Lease Losses Write-offs, Net	(146)	(88)	(192)
Commercial real estate
Allowance for loan and lease losses
Balance at beginning of year	20,930	26,540	23,656
Provision for loan and lease losses	847	(7,291)	5,365
Loans charged off	(4,835)	(1,038)	(4,983)
Recoveries	4,106	2,719	2,502
Allowance for Loan and Lease Losses Write-offs, Net	729	(1,681)	2,481
Residential
Allowance for loan and lease losses
Balance at beginning of year	4,683	3,208	4,014
Provision for loan and lease losses	492	1,695	(655)
Loans charged off	(422)	(435)	(387)
Recoveries	211	215	236
Allowance for Loan and Lease Losses Write-offs, Net	211	220	151
Home equity
Allowance for loan and lease losses
Balance at beginning of year	4,935	3,043	3,943
Provision for loan and lease losses	829	1,778	(175)
Loans charged off	(1,725)	(913)	(1,445)
Recoveries	1,309	1,027	720
Allowance for Loan and Lease Losses Write-offs, Net	416	(114)	725
Installment
Allowance for loan and lease losses
Balance at beginning of year	307	388	386
Provision for loan and lease losses	(85)	(90)	53
Loans charged off	(435)	(225)	(386)
Recoveries	575	234	335
Allowance for Loan and Lease Losses Write-offs, Net	(140)	(9)	51
Credit card
Allowance for loan and lease losses
Balance at beginning of year	1,316	1,559	1,773
Provision for loan and lease losses	1,744	408	673
Loans charged off	(1,720)	(857)	(1,190)
Recoveries	191	206	303
Allowance for Loan and Lease Losses Write-offs, Net	$ 1,529	$ 651	$ 887

ALLOWANCE FOR LOAN AND LEASE _4

ALLOWANCE FOR LOAN AND LEASE LOSSES - Changes in the Allowance for Loan and Lease Losses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance	$ 56,542	$ 54,021	$ 57,961	$ 53,398
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	1,160	779
Ending allowance on loans collectively evaluated for impairment	55,382	53,242
Impaired Financing Receivable, Related Allowance	56,542	54,021
Loans and Leases:
Ending balance of loans individually evaluated for impairment	86,809	41,627
Ending balance of loans collectively evaluated for impairment	8,737,405	5,971,556
Loans and Leases Receivable, Net of Deferred Income	8,824,214	6,013,183
Provision for loan and lease losses	14,586	3,582	10,140
Allowance for Loan and Lease Losses, Write-offs	20,670	13,663	11,114
Allowance for Loan and Lease Loss, Recovery of Bad Debts	8,605	6,141	5,537
Commercial & industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance	18,746	17,598	19,225	16,995
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	667	169
Ending allowance on loans collectively evaluated for impairment	18,079	17,429
Impaired Financing Receivable, Related Allowance	18,746	17,598
Loans and Leases:
Ending balance of loans individually evaluated for impairment	37,633	7,331
Ending balance of loans collectively evaluated for impairment	2,477,028	1,905,412
Loans and Leases Receivable, Net of Deferred Income	2,514,661	1,912,743
Provision for loan and lease losses	10,615	6,917	3,705
Allowance for Loan and Lease Losses, Write-offs	11,533	10,194	2,630
Allowance for Loan and Lease Loss, Recovery of Bad Debts	2,066	1,650	1,155
Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance	1,130	675	716	821
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0	0
Ending allowance on loans collectively evaluated for impairment	1,130	675
Impaired Financing Receivable, Related Allowance	1,130	675
Loans and Leases:
Ending balance of loans individually evaluated for impairment	22	82
Ending balance of loans collectively evaluated for impairment	93,393	89,265
Loans and Leases Receivable, Net of Deferred Income	93,415	89,347
Provision for loan and lease losses	454	(42)	(106)
Allowance for Loan and Lease Losses, Write-offs	0	0	0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1	1	1
Construction real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance	3,413	3,577	3,282	1,810
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0	0
Ending allowance on loans collectively evaluated for impairment	3,413	3,577
Impaired Financing Receivable, Related Allowance	3,413	3,577
Loans and Leases:
Ending balance of loans individually evaluated for impairment	9	29
Ending balance of loans collectively evaluated for impairment	548,926	467,701
Loans and Leases Receivable, Net of Deferred Income	548,935	467,730
Provision for loan and lease losses	(310)	207	1,280
Allowance for Loan and Lease Losses, Write-offs	0	1	93
Allowance for Loan and Lease Loss, Recovery of Bad Debts	146	89	285
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance	21,048	20,930	26,540	23,656
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	461	448
Ending allowance on loans collectively evaluated for impairment	20,587	20,482
Impaired Financing Receivable, Related Allowance	21,048	20,930
Loans and Leases:
Ending balance of loans individually evaluated for impairment	25,022	21,542
Ending balance of loans collectively evaluated for impairment	3,729,659	2,468,549
Loans and Leases Receivable, Net of Deferred Income	3,754,681	2,490,091
Provision for loan and lease losses	847	(7,291)	5,365
Allowance for Loan and Lease Losses, Write-offs	4,835	1,038	4,983
Allowance for Loan and Lease Loss, Recovery of Bad Debts	4,106	2,719	2,502
Residential real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance	4,964	4,683	3,208	4,014
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	32	160
Ending allowance on loans collectively evaluated for impairment	4,932	4,523
Impaired Financing Receivable, Related Allowance	4,964	4,683
Loans and Leases:
Ending balance of loans individually evaluated for impairment	17,598	7,932
Ending balance of loans collectively evaluated for impairment	938,048	463,459
Loans and Leases Receivable, Net of Deferred Income	955,646	471,391
Provision for loan and lease losses	492	1,695	(655)
Allowance for Loan and Lease Losses, Write-offs	422	435	387
Allowance for Loan and Lease Loss, Recovery of Bad Debts	211	215	236
Home equity
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance	5,348	4,935	3,043	3,943
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0	2
Ending allowance on loans collectively evaluated for impairment	5,348	4,933
Impaired Financing Receivable, Related Allowance	5,348	4,935
Loans and Leases:
Ending balance of loans individually evaluated for impairment	6,351	4,456
Ending balance of loans collectively evaluated for impairment	810,931	489,148
Loans and Leases Receivable, Net of Deferred Income	817,282	493,604
Provision for loan and lease losses	829	1,778	(175)
Allowance for Loan and Lease Losses, Write-offs	1,725	913	1,445
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1,309	1,027	720
Installment
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance	362	307	388	386
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0	0
Ending allowance on loans collectively evaluated for impairment	362	307
Impaired Financing Receivable, Related Allowance	362	307
Loans and Leases:
Ending balance of loans individually evaluated for impairment	174	255
Ending balance of loans collectively evaluated for impairment	93,038	41,331
Loans and Leases Receivable, Net of Deferred Income	93,212	41,586
Provision for loan and lease losses	(85)	(90)	53
Allowance for Loan and Lease Losses, Write-offs	435	225	386
Allowance for Loan and Lease Loss, Recovery of Bad Debts	575	234	335
Credit card
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance	1,531	1,316	1,559	$ 1,773
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0	0
Ending allowance on loans collectively evaluated for impairment	1,531	1,316
Impaired Financing Receivable, Related Allowance	1,531	1,316
Loans and Leases:
Ending balance of loans individually evaluated for impairment	0	0
Ending balance of loans collectively evaluated for impairment	46,382	46,691
Loans and Leases Receivable, Net of Deferred Income	46,382	46,691
Provision for loan and lease losses	1,744	408	673
Allowance for Loan and Lease Losses, Write-offs	1,720	857	1,190
Allowance for Loan and Lease Loss, Recovery of Bad Debts	$ 191	$ 206	$ 303

PREMISES AND EQUIPMENT - Schedu

PREMISES AND EQUIPMENT - Schedule of Premises and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 320,902	$ 222,550
Less accumulated depreciation and amortization	105,250	97,514
Total premises and equipment	215,652	125,036
Operating Leases, Rent Expense	9,100	7,100	$ 7,900
Land and land improvements [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	57,701	41,711
Buildings [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	161,817	104,576
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	66,567	55,165
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	29,086	19,377
Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 5,731	$ 1,721

PREMISES AND EQUIPMENT - Operat

PREMISES AND EQUIPMENT - Operating leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Operating Leased Assets [Line Items]
2,019	$ 9,568
2,020	9,179
2,021	8,284
2,022	5,016
2,023	4,269
Thereafter	15,496
Total	$ 51,812

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS GOODWILL AND OTHER INTANGIBLE ASSETS-Schedule of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Balance at beginning of year	$ 204,084	$ 204,084	$ 204,084
Goodwill	676,167	0	0
Balance at end of year	$ 880,251	$ 204,084	$ 204,084

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLE ASSETS GOODWILL AND OTHER INTANGIBLE ASSETS-Schedule of Future Amortization Expense (Details) $ in Thousands	Dec. 31, 2018USD ($)
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 8,800
Finite-Lived Intangible Assets, Amortization Expense, Year Two	7,010
Finite-Lived Intangible Assets, Amortization Expense, Year Three	5,602
Finite-Lived Intangible Assets, Amortization Expense, Year Four	3,417
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 3,155

GOODWILL AND OTHER INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLE ASSETS GOODWILL AND OTHER INTANGIBLE ASSETS--Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 676,167	$ 0	$ 0
Other intangibles	40,800	3,800
Finite-Lived Core Deposits, Gross	37,900	3,300
Finite-Lived Intangible Assets, Period Increase (Decrease)	41,700	0	0
Finite-Lived Intangible Assets, Amortization Expense	$ 7,700	$ 1,300	$ 1,600
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization method	accelerated basis
Estimated weighted average life (in years)	8 years 11 months

DEPOSITS DEPOSITS (Details)

DEPOSITS DEPOSITS (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deposits [Abstract]
Time Deposit Maturities, Next Twelve Months	$ 1,407,996
Time Deposit Maturities, Year Two	471,183
Time Deposit Maturities, Year Three	163,575
Time Deposit Maturities, Year Four	110,170
Time Deposit Maturities, Year Five	20,112
Time Deposit Maturities, after Year Five	528
Time	$ 2,173,564	$ 1,317,105

DEPOSITS DEPOSITS-Additional In

DEPOSITS DEPOSITS-Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deposits [Abstract]
Time Deposits, at or Above FDIC Insurance Limit	$ 284.9	$ 174.8

BORROWINGS BORROWINGS - Repurch

BORROWINGS BORROWINGS - Repurchase Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Securities Sold under Agreements to Repurchase	$ 84,591
Carrying Value of Securities Sold under Repurchase Agreements and Deposits Received for Securities Loaned	85,500	$ 72,800
Residential Mortgage Backed Securities [Member]
Securities Sold under Agreements to Repurchase	22,369
Collateralized Mortgage Obligations [Member]
Securities Sold under Agreements to Repurchase	$ 62,222

BORROWINGS - Schedule of Short-

BORROWINGS - Schedule of Short-term Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 30,000
Commitments outstanding to extend credit	0	$ 0
Short-term Debt	$ 1,040,691	$ 814,565	$ 807,912
Short-term debt interest rate	2.33%	1.32%	0.58%
Short-term debt, average for the year	$ 947,427	$ 830,365	$ 880,457
Short-term debt, average rate (as a percent)	1.90%	0.98%	0.50%
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Short-term Debt [Line Items]
Short-term Debt	$ 183,591	$ 72,265	$ 120,212
Short-term debt interest rate	1.65%	0.19%	0.12%
Short-term debt, average for the year	$ 87,221	$ 69,766	$ 89,157
Short-term debt, average rate (as a percent)	0.58%	0.19%	0.05%
Short-term debt, maximum month-end balances	$ 183,591	$ 130,633	$ 122,242
Federal Home Loan Bank Borrowings [Member]
Short-term Debt [Line Items]
Short-term Debt	$ 857,100	$ 742,300	$ 687,700
Short-term debt interest rate	2.48%	1.43%	0.66%
Short-term debt, average for the year	$ 857,028	$ 760,558	$ 791,259
Short-term debt, average rate (as a percent)	2.03%	1.05%	0.55%
Short-term debt, maximum month-end balances	$ 1,170,800	$ 957,700	$ 1,035,000
Short-term Debt [Member]
Short-term Debt [Line Items]
Short-term debt, average for the year	$ 3,178	$ 41	$ 41
Short-term debt, average rate (as a percent)	4.36%	4.07%	3.56%
Short-term debt, maximum month-end balances	$ 10,000	$ 0	$ 0

BORROWINGS - Schedule of Long-t

BORROWINGS - Schedule of Long-term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amount
Subordinated Debt	$ 170,550	$ 120,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	(1,185)	(1,362)
FHLB long-term advances	400,599	241
Other Long-term Debt	775	775
Total long-term debt	$ 570,739	$ 119,654
Average Rate [Abstract]
Debt, Weighted Average Interest Rate	5.28%	5.13%
Federal Home Loan Bank	2.08%	1.09%
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	0.00%	0.00%
Long-term Debt, Weighted Average Interest Rate, at Point in Time	3.04%	5.14%
Maturities of Long-term Debt [Abstract]
2,019	$ 157,914
2,020	104,274
2,021	19,007
2,022	49,404
2,023	0
Thereafter	$ 240,140

BORROWINGS Borrowings - - Addit

BORROWINGS Borrowings - - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Subordinated Debt	$ 170,550	$ 120,000
Debt, Weighted Average Interest Rate	5.28%	5.13%
Commitments outstanding to extend credit	$ 0	$ 0
Subordinated debt, original issue	$ 120,000
Subordinated Borrowing, Interest Rate	5.125%
Book value of FHLB collateral	$ 5,700,000
Private Placement [Member]
Debt Instrument [Line Items]
Subordinated Debt	$ 8,400
Debt, Weighted Average Interest Rate	7.40%
Subordinated Debt [Member]
Debt Instrument [Line Items]
Subordinated Debt	$ 49,500
Debt Instrument Maturity Period	30 years
DebtInstrumentMinimumCallablePeriod	5 years
Private Placement [Member]
Debt Instrument [Line Items]
DebtInstrumentMinimumCallablePeriod	5 years

DERIVATIVES - Additional Inform

DERIVATIVES - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 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
Number of counterparties \| entity	13	13
Derivative Asset	$ 29,189	$ 12,682
Interest-bearing deposit swap	2,719,980	1,674,080
Derivative Liability	29,188	12,687
Other Credit Derivatives [Member]
Derivative [Line Items]
Outstanding liability from counterparty contracts		100
Interest-bearing deposit swap	12,300	15,400
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Interest-bearing deposit swap	20,800	12,300
Credit Risk Contract [Member]
Derivative [Line Items]
Outstanding liability from counterparty contracts	100	54
Interest-bearing deposit swap	138,400	95,900
Derivative [Member] \| Other Liabilities [Member]
Derivative [Line Items]
Derivative Asset	4,900
Interest-bearing deposit swap	$ 1,400,000	837,500
Derivative Liability		$ 1,300

DERIVATIVES - Summary of Deriva

DERIVATIVES - Summary of Derivative Financial Instruments and Balances (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Interest-bearing deposit swap	$ 2,719,980	$ 1,674,080
Derivative Asset	29,189	12,682
Estimate Fair Value Loss	(29,188)	(12,687)
Fair Value Hedges \| Matched interest rate swaps \| Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Interest-bearing deposit swap	1,359,990	837,040
Derivative Asset	11,787	5,529
Estimate Fair Value Loss	(17,401)	(7,158)
Fair Value Hedges \| Matched interest rate swaps \| Accrued interest and other assets
Derivatives, Fair Value [Line Items]
Interest-bearing deposit swap	1,359,990	837,040
Derivative Asset	17,402	7,153
Estimate Fair Value Loss	$ (11,787)	$ (5,529)

DERIVATIVES DERIVATIVES - Discl

DERIVATIVES DERIVATIVES - Disclosure by Type of Financial Instrument (Details) - Fair Value Hedges - Matched interest rate swaps - Accrued interest and other liabilities - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 29,189	$ 12,687
Derivative Liability, Fair Value, Gross Asset	(14,577)	2,279
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 14,612	$ 14,966

DERIVATIVES - Derivative Financ

DERIVATIVES - Derivative Financial Instruments, Average Remaining Maturity and the Weighted-Average Interest Rates being Paid and Received (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional Value	$ 2,719,980	$ 1,674,080
Asset conversion swaps
Derivative [Line Items]
Notional Value	$ 2,719,980
Average Maturity (years)	6 years 2 months
Fair Value	$ 1
Weighted-Average Rate Receive	4.68%
Weighted-Average Rate Pay	4.68%
Asset conversion swaps \| Derivative Financial Instruments Receive Fixed Pay Variable
Derivative [Line Items]
Notional Value	$ 1,359,990
Average Maturity (years)	6 years 2 months
Fair Value	$ 5,615
Weighted-Average Rate Receive	4.70%
Weighted-Average Rate Pay	4.67%
Asset conversion swaps \| Derivative Financial Instruments Receive Variable Pay Fixed
Derivative [Line Items]
Notional Value	$ 1,359,990
Average Maturity (years)	6 years 2 months
Fair Value	$ (5,614)
Weighted-Average Rate Receive	4.67%
Weighted-Average Rate Pay	4.70%

RELATED PARTIES TRANSACTIONS (D

RELATED PARTIES TRANSACTIONS (Details) $ in Thousands	12 Months Ended
RELATED PARTIES TRANSACTIONS (Details) $ in Thousands	Dec. 31, 2018USD ($)
Loans to Related Parties [Roll Forward]
Beginning balance	$ 9,873
Additions	2,108
Deductions	(9,249)
Ending balance	2,732
Loans 90 days past due	$ 0

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Detail) - USD ($)	12 Months Ended
COMMITMENTS AND CONTINGENCIES (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Line Items]
Reserves for unfunded commitments	$ 700,000	$ 500,000
Letters of credit issued to guarantee performance of a client to a third party	32,700,000	25,300,000
Affordable Housing Program Obligation	39,400,000	35,900,000
Commitments outstanding to extend credit	0	0
Loans and Leases Receivable, Commitments, Variable Rates	2,900,000,000
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	5,439,000	16,806,000	$ 2,691,000
Income tax expense	41,626,000	19,376,000	42,205,000
Other Noninterest Expense	36,089,000	35,556,000	$ 17,182,000
Amortization Method Qualified Affordable Housing Project Investments, Amortization	5,700,000	4,200,000
Affordable housing contingent commitment	0	0
Estimated Litigation Liability	0	0
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	3,900,000	3,000,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	3,900,000	$ 3,000,000
Loans and Leases Receivable, Commitments, Fixed Rates	$ 174,000,000
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	1 year
Loan Commitments, Fixed Rate, Maturities, Maximum	30 years	29 years
Commitments to Extend Credit
Commitments and Contingencies Disclosure [Line Items]
Commitments outstanding to extend credit	$ 3,000,000,000	$ 2,100,000,000
Minimum
Commitments and Contingencies Disclosure [Line Items]
Loans and Leases Receivable, Commitments, Variable Rates		0
Maximum
Commitments and Contingencies Disclosure [Line Items]
Loans and Leases Receivable, Commitments, Variable Rates		0.2100
Affordable housing investment [Member]
Commitments and Contingencies Disclosure [Line Items]
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	4,900,000	3,200,000
Historic tax credit [Member]
Commitments and Contingencies Disclosure [Line Items]
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	$ 500,000	13,700,000
Income tax expense		12,500,000
Other Noninterest Expense		$ 11,300,000

INCOME TAXES (Detail)

INCOME TAXES (Detail) - USD ($) $ in Thousands	12 Months Ended
INCOME TAXES (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current expense [Abstract]
Federal	$ 34,330	$ 22,599	$ 40,537
State	1,029	1,265	1,322
Total current expense	35,359	23,864	41,859
Deferred (benefit) expense [Abstract]
Federal	4,675	(4,657)	528
State	1,592	169	(182)
Total deferred (benefit) expense	6,267	(4,488)	346
Income tax expense	41,626	19,376	42,205
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes computed at federal statutory rate on income before income taxes (21% in 2018; 35% in 2017 and 2016)	44,986	40,657	45,756
Benefit from tax-exempt income	(4,499)	(3,427)	(2,911)
Tax credits	(5,439)	(16,806)	(2,691)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	0	(8,191)	0
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount	0	4,599	0
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Amount	(565)	(1,449)	(72)
State income taxes, net of federal tax benefit	2,070	932	741
Effective Income Tax Rate Reconciliation, ASU 2014-10, Affordable Housing Amortization, Amount	4,725	2,798	1,923
Other	348	263	(541)
Income tax expense	41,626	19,376	42,205
Deferred tax assets [Abstract]
Allowance for loan and lease losses	12,782	12,134
Deferred Tax Assets Fair Value Adjustments On Acquisitions	11,199	369
Deferred compensation	392	384
Postretirement benefits other than pension liability	676	564
Accrued stock-based compensation	1,145	932
Other real estate owned write-downs	118	97
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Impairment Losses	1,160	616
Accrued expenses	5,808	3,051
Deferred Tax Assets, Unrealized Losses on Investment Securities and Derivatives	3,221	249
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	3,119	0
Deferred Tax Assets, Tax Credit Carryforwards	873	0
Other	425	339
Total deferred tax assets	40,918	18,735
Deferred tax liabilities [Abstract]
Tax depreciation greater than book depreciation	(9,530)	(2,510)
FHLB and FRB stock	(4,044)	(3,384)
Mortgage-servicing rights	(2,285)	(343)
Leasing activities	(3,881)	(2,792)
Deferred Tax Liabilities, Prepaid Pension Cost	6,614	8,888
Intangible assets	(12,310)	(11,559)
Deferred loan fees and costs	(131)	(371)
Prepaid expenses	(582)	(210)
Deferred Tax Liabilities, Partnership Interests	2,367	1,230
Other	(1,867)	(2,415)
Deferred Tax Liabilities, Gross	(43,611)	(33,702)
Total deferred tax liabilities	(2,693)	(14,967)
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Balance at beginning of year	3,735	3,735
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	0	0
Balance at end of year	$ 3,735	$ 3,735	$ 3,735
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	35.00%	35.00%
Deferred Tax Assets Operating Loss Carryforwards State And Local Acquired	$ 3,900
Tax Credit Carryforward, Amount	900
Deferred taxes, business combination, valuation allowance	0	$ 0
Retained Earnings For Which No Deferred Income Tax Liability Has Been Recognized	16,100
Deferred Tax Liability Not Recognized Amount Of Liability Related To Allocation Of Previously Acquired Institutions	3,400
Unrecognized tax benefits affecting income tax rate	2,900	2,900
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	$ 0	$ 0

EMPLOYEE BENEFIT PLANS EMPLOYEE

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Pension Cost (Reversal of Cost)	$ 859	$ (628)	$ (1,153)
Payment for Pension Benefits	$ 0	0	0
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year				$ 0
Defined Contribution Plan, Maximum Annual Contribution Percent by Employee	50.00%
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	$ 71,154	62,729
Service cost	6,501	4,894	5,034
Interest cost	2,394	2,325	2,262
Actuarial gain (loss)	(4,032)	6,107
Defined Benefit Plan, Benefit Obligation, Benefits Paid	7,731	4,901
Benefit obligation at end of year	68,286	71,154	62,729
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	144,349	131,011
Actual return on plan assets	(6,540)	18,239
Defined Benefit Plan, Plan Assets, Benefits Paid	7,731	4,901
Fair value of plan assets at end of year	130,078	144,349	131,011
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Assets				61,792	$ 73,195
Liabilities				0	0
Net amount recognized				61,792	73,195
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Abstract]
Net actuarial loss				43,711	33,580
Net prior service cost				(1,508)	(1,921)
Deferred tax assets				(9,613)	(12,028)
Net amount recognized				32,590	19,631	$ 22,803	$ 24,048
Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment and Disproportionate Tax Effect Net Of Tax	12,959
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	8,180	(3,172)	(1,245)
Accumulated benefit obligation				66,320	69,678
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	6,501	4,894	5,034
Interest cost	2,394	2,325	2,262
Expected return on plan assets	(9,811)	(9,358)	(9,644)
Amortization of prior service cost	(413)	(413)	(413)
Defined Benefit Plan, Amortization of Gain (Loss)	2,188	1,924	1,608
Net periodic benefit (income) cost	859	(628)	(1,153)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax [Abstract]
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss), Net Gain (Loss), before Tax	12,319	(2,775)	(884)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax	0	0	0
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss), Net Prior Service Cost, before Tax	413	413	413
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	(2,188)	(1,924)	(1,608)
Total recognized in accumulated other comprehensive income	10,544	(4,286)	(2,079)
Total recognized in net periodic benefit cost and accumulated other comprehensive income	$ 11,403	$ (4,914)	$ (3,232)
Amortization of loss				1,867	2,090	1,754
Amortization of prior service credit				$ (413)	$ (413)	$ (413)
Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate				4.31%	3.43%	3.88%
Rate of compensation increase				3.50%	3.50%	3.50%
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	3.43%	3.88%	4.05%
Expected return on plan assets	7.25%	7.25%	7.50%
Rate of compensation increase	3.50%	3.50%	3.50%
Fair value measurments	$ 144,349	$ 131,011	$ 131,011	$ 130,078	$ 144,349	$ 131,011
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2,019				4,396
2,020				5,280
2,021				5,229
2,022				4,739
2,023				4,917
Thereafter				29,948
Defined Contribution Plan [Abstract]
Defined Contribution Plan, Cost	0	1,900	$ 800
Defined Benefit Plan, Fair Value of Plan Assets Excluding Accrued Interest and Dividends				130,078	144,349
Fair Value, Inputs, Level 1 [Member]
Defined Contribution Plan [Abstract]
Defined Benefit Plan, Fair Value of Plan Assets Excluding Accrued Interest and Dividends				122,025	137,496
Fair Value, Inputs, Level 2 [Member]
Defined Contribution Plan [Abstract]
Defined Benefit Plan, Fair Value of Plan Assets Excluding Accrued Interest and Dividends				8,053	6,853
Fair Value, Inputs, Level 3 [Member]
Defined Contribution Plan [Abstract]
Defined Benefit Plan, Fair Value of Plan Assets Excluding Accrued Interest and Dividends				0	0
Cash
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	175
Fair value of plan assets at end of year	216	175
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	175	175		216	175
Cash \| Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	175
Fair value of plan assets at end of year	216	175
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	175	175		216	175
Cash \| Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0
Fair value of plan assets at end of year	0	0
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	0	0		0	0
Cash \| Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0
Fair value of plan assets at end of year	0	0
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	0	0		0	0
US Government Agencies Debt Securities [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	6,853
Fair value of plan assets at end of year	8,053	6,853
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	6,853	6,853		8,053	6,853
US Government Agencies Debt Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0
Fair value of plan assets at end of year	0	0
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	0	0		0	0
US Government Agencies Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	6,853
Fair value of plan assets at end of year	8,053	6,853
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	6,853	6,853		8,053	6,853
US Government Agencies Debt Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0
Fair value of plan assets at end of year	0	0
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	0	0		0	0
Fixed income mutual funds
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	69,154
Fair value of plan assets at end of year	74,453	69,154
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	69,154	69,154		74,453	69,154
Fixed income mutual funds \| Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	69,154
Fair value of plan assets at end of year	74,453	69,154
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	69,154	69,154		74,453	69,154
Fixed income mutual funds \| Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0
Fair value of plan assets at end of year	0	0
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	0	0		0	0
Fixed income mutual funds \| Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0
Fair value of plan assets at end of year	0	0
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	0	0		0	0
Equity mutual funds
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	68,167
Fair value of plan assets at end of year	47,356	68,167
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	68,167	68,167		47,356	68,167
Equity mutual funds \| Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	68,167
Fair value of plan assets at end of year	47,356	68,167
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	68,167	68,167		47,356	68,167
Equity mutual funds \| Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0
Fair value of plan assets at end of year	0	0
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	0	0		0	0
Equity mutual funds \| Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0
Fair value of plan assets at end of year	0	0
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Fair value measurments	$ 0	$ 0		$ 0	$ 0

EMPLOYEE BENEFIT PLANS Defined

EMPLOYEE BENEFIT PLANS Defined Benefit Plan, Fair Value on Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
defined benefit plan, fair value of plan assets excluding accrued interest and dividends [Line Items]
Defined Benefit Plan, Plan Assets, Benefits Paid	$ 7,731	$ 4,901
Defined Contribution Plan, Cost	0	1,900	$ 800
Defined Benefit Plan, Fair Value of Plan Assets Excluding Accrued Interest and Dividends	130,078	144,349
Fair Value, Inputs, Level 1 [Member]
defined benefit plan, fair value of plan assets excluding accrued interest and dividends [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets Excluding Accrued Interest and Dividends	122,025	137,496
Fair Value, Inputs, Level 2 [Member]
defined benefit plan, fair value of plan assets excluding accrued interest and dividends [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets Excluding Accrued Interest and Dividends	8,053	6,853
Fair Value, Inputs, Level 3 [Member]
defined benefit plan, fair value of plan assets excluding accrued interest and dividends [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets Excluding Accrued Interest and Dividends	$ 0	$ 0

REVENUE RECOGNITION REVENUE R_2

REVENUE RECOGNITION REVENUE RECOGNITION (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Revenue Recognition and Deferred Revenue [Abstract]
Interchange income	$ 31.3
Credit card expense	$ 11

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Comprehensive Income (Loss), before Reclassification Adjustments and Tax [Abstract]
Unrealized gain (loss) on debt securities	$ (14,461)	$ 8,447	$ 751
Unrealized gain (loss) on derivatives	628	810	809
Retirement obligations	(12,319)	2,775	884
Total	(26,152)	12,032	2,444
Other Comprehensive Income (Loss) Reclassifications before Tax [Abstract]
Unrealized gain (loss) on debt securities	(161)	1,649	234
Unrealized gain (loss) on derivatives	0	0	0
Retirement obligation	1,775	1,511	1,195
Total	(1,936)	138	(961)
Transactions Pre-tax
Unrealized gain (loss) on debt securities	(14,300)	6,798	517
Unrealized gain (loss) on derivatives	628	810	809
Retirement obligation	(10,544)	4,286	2,079
Total	(24,216)	11,894	3,405
Transactions Tax-effect
Unrealized gain (loss) on debt securities	3,071	(2,431)	(133)
Unrealized gain (loss) on derivatives	(144)	(296)	(301)
Retirement obligation	2,364	(1,114)	(834)
Total	5,291	(3,841)	(1,268)
Transactions Net of tax
Unrealized gain (loss) on debt securities	(11,229)	4,367	384
Unrealized gain (loss) on derivatives	484	514	508
Retirement obligation	(8,180)	3,172	1,245
Total	(18,925)	8,053	2,137
Cumulative effect of accounting change
Unrealized gain (loss) on debt securities	(190)
Unrealized gain (loss) on derivatives	(124)
Retirement obligation	(4,779)
Total	(5,093)
Balances Net of tax
Unrealized gain (loss) on debt securities	(11,601)	(182)	(4,549)	$ (4,933)
Unrealized gain (loss) on derivatives	(217)	(577)	(1,091)	(1,599)
Retirement obligation	(32,590)	(19,631)	(22,803)	(24,048)
Total	$ (44,408)	$ (20,390)	$ (28,443)	$ (30,580)

ACCUMULATED OTHER COMPREHENSI_4

ACCUMULATED OTHER COMPREHENSIVE INCOME AMOUNT RECLASSIFIED FROM ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Realized gains and losses on securities available for sale	$ (161)	$ 1,649	$ 234
Amortization of prior service cost	413	413	413
Recognized net actuarial loss	(2,188)	(1,924)	(1,608)
Other Comprehensive Income, Reclassification, Amortization of Defined Benefit Plans items, Pre-tax	(1,775)	(1,511)	(1,195)
Total reclassifications for the period, before tax	$ (1,936)	$ 138	$ (961)

CAPITAL - Risk-Based Capital (D

CAPITAL - Risk-Based Capital (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital	$ 1,215,613	$ 755,735
Subordinated debt, original issue	120,000
Excess Capital	$ 432,800
Risk Based Ratios [Abstract]
Common Equity Tier One Capital to Risk-Weighted Assets	11.87%	10.63%
Common Equity Tier One Capital Required for Capital Adequacy	$ 652,874	$ 408,746
Common Equity Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets	6.375%	5.75%
Common Equity Tier One Risk Based Capital Required for Capital Adequacy Fully Phased In Basel III	$ 716,881	$ 497,604
Common Equity Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Fully Phased In Basel III	7.00%	7.00%
Tier One Risk Based Capital	$ 1,257,366	$ 755,839
Tier One Risk Based Capital to Risk Weighted Assets	12.28%	10.63%
Tier One Risk Based Capital Required for Capital Adequacy	$ 806,491	$ 515,376
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	7.875%	7.25%
Capital Conservation Buffer-Fully Phased-In	2.50%
Capital Conservation Buffer-Phased-In Incremental Change	0.625%
Tier One Risk Based Capital [Abstract]
Tier One Risk Based Capital Required for Capital Adequacy Fully Phased In Basel III	$ 870,499	$ 604,233
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Fully Phased In Basel III	8.50%	8.50%
Capital	$ 1,444,146	$ 929,148
Capital to Risk Weighted Assets	14.10%	13.07%
Capital Required for Capital Adequacy	$ 1,011,314	$ 657,548
Capital Required for Capital Adequacy to Risk Weighted Assets	9.875%	9.25%
Capital [Abstract]
Capital Required for Capital Adequacy Fully Phased In Basel III	$ 1,075,322	$ 746,406
Capital Required for Capital Adequacy to Risk Weighted Assets Fully Phased In Basel III	10.50%	10.50%
Tier One Leverage Capital	$ 1,257,366	$ 755,839
Tier One Leverage Capital [Abstract]
Tier One Leverage Capital Required for Capital Adequacy Fully Phased In Basel III	$ 517,958	$ 342,198
Tier One Leverage Capital Required for Capital Adequacy to Average Assets Fully Phased In Basel III	4.00%	4.00%
Tier One Leverage Capital to Average Assets	9.71%	8.84%
Tier One Leverage Capital Required for Capital Adequacy	$ 517,958	$ 342,198
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital	$ 1,279,492	$ 794,251
Risk Based Ratios [Abstract]
Common Equity Tier One Capital to Risk-Weighted Assets	12.50%	11.21%
Common Equity Tier One Capital Required for Capital Adequacy	$ 652,590	$ 407,220
Common Equity Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets	6.375%	5.75%
Common Equity Tier One Risk Based Capital Required for Capital Adequacy Fully Phased In Basel III	$ 716,570	$ 495,746
Common Equity Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Fully Phased In Basel III	7.00%	7.00%
Tier One Risk Based Capital	$ 1,279,596	$ 794,355
Tier One Risk Based Capital to Risk Weighted Assets	12.50%	11.22%
Tier One Risk Based Capital Required for Capital Adequacy	$ 806,141	$ 513,452
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	7.875%	7.25%
Common Equity Tier One Risk Based Capital Required to be Well Capitalized To Risk Weighted Assets	$ 665,386	$ 460,336
Common Equity Tier One Risk Based Capital Required to be Well Capitalized To Risk Weighted Assets	6.50%	6.50%
Tier One Risk Based Capital [Abstract]
Tier One Risk Based Capital Required for Capital Adequacy Fully Phased In Basel III	$ 870,120	$ 601,978
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Fully Phased In Basel III	8.50%	8.50%
Capital	$ 1,344,388	$ 856,363
Capital to Risk Weighted Assets	13.13%	12.09%
Capital Required for Capital Adequacy	$ 1,010,875	$ 655,093
Capital Required for Capital Adequacy to Risk Weighted Assets	9.875%	9.25%
Capital [Abstract]
Capital Required for Capital Adequacy to Risk Weighted Assets	$ 818,937	$ 566,567
Capital Required for Capital Adequacy Fully Phased In Basel III	$ 1,074,855	$ 743,619
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Capital Required for Capital Adequacy to Risk Weighted Assets Fully Phased In Basel III	10.50%	10.50%
Tier One Leverage Capital	$ 1,279,596	$ 794,355
Tier One Leverage Capital [Abstract]
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	1,023,671	708,209
Tier One Leverage Capital Required for Capital Adequacy Fully Phased In Basel III	$ 517,710	$ 342,113
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Tier One Leverage Capital Required for Capital Adequacy to Average Assets Fully Phased In Basel III	4.00%	4.00%
Tier One Leverage Capital to Average Assets	9.89%	9.29%
Tier One Leverage Capital Required for Capital Adequacy	$ 517,710	$ 342,113
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	$ 647,138	$ 427,642
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%

CAPITAL - Share Repurchase (Det

CAPITAL - Share Repurchase (Details) - shares	12 Months Ended
CAPITAL - Share Repurchase (Details) - shares	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Oct. 23, 2012
Capital [Abstract]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased				5,000,000
Treasury Stock, Shares, Acquired	0	0
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased			3,509,133

STOCK OPTIONS AND AWARDS (Detai

STOCK OPTIONS AND AWARDS (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation	$ 6,219	$ 5,446	$ 5,354
Total unrecognized compensation cost				$ 6,900
Unrecognized compensation cost, period for recognition (in years)	1 year 343 days
Share-based Compensation Arrangement by Share-based Payment Award, Option Term	10 years
Options outstanding at end of year	11,800	11,800		62,410
Number of Shares Available for Grant				1,877,079
Activity for stock option plan [Roll Forward]
Outstanding at beginning of year (in shares)	11,800
Granted (in shares)	0	0	0
Exercised (in shares)	(32,941)
Forfeited or expired (in shares)	0
Outstanding at end of year (in shares)	62,410	11,800
Exercised (in shares)				62,410
Weighted average exercise price, outstanding at beginning of year (in dollars per share)	$ 11.64
Weighted average exercise price, granted (in dollars per share)	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Other Share Increase (Decrease)	83,551
Share-based Compensation Arrangements by Share-based Payment Award, Options, Other Share Increase (Decrease) in Period, Weighted Average Exercise Price	$ 8.54
Weighted average exercise price, exercised (in dollars per share)	8.62
Weighted average exercise price, forfeited or expired (in dollars per share)	0
Weighted average exercise price, outstanding at end of year (in dollars per share)	$ 9.08	$ 11.64
Weighted average exercise price, Exercisable (in dollars per share)				$ 9.08
Weighted average remaining contractual term, outstanding at end of year (in years)	3 years 263 days
Weighted average remaining contractual life, exercisable at end of year (in years)	3 years 263 days
Aggregate intrinsic value, outstanding at end of year				$ 914
Aggregate intrinsic value, exercisable at end of year				$ 914
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Total intrinsic value of options exercised	$ 734	$ 1,533	$ 661
Proceeds from exercise of stock options	284	341	801
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	1,439	1,991	1,958
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested in period, total fair value	$ 5,600	$ 5,600	$ 4,400
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Number of shares nonvested at beginning of year	468,372	648,817	643,641
Number of shares granted	303,930	234,529	317,695
Number of shares vested	(267,031)	(307,825)	(263,713)
Number of shares forfeited	(42,825)	(107,149)	(48,806)
Number of shares nonvested at end of year	462,446	468,372	648,817
Weighted average of shares fair value, nonvested at beginning of year	$ 21.63	$ 17.82	$ 17.21
Weighted average of shares fair value granted	28.94	27.36	18.13
Weighted average of shares fair value vested	20.94	18.12	16.82
Weighted average of shares fair value forfeited	26.38	21.18	17.37
Weighted average of shares fair value, nonvested at end of year	$ 26.39	$ 21.63	$ 17.82

EARNINGS PER COMMON SHARE - Com

EARNINGS PER COMMON SHARE - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator for basic and diluted earnings per share -income available to common shareholders:
Net income	$ 172,595	$ 96,787	$ 88,526
Denominator for basic earnings per share - weighted average shares	88,582,090	61,529,460	61,206,093
Effect of dilutive securities -
Employee stock awards	514,680	581,329	729,335
Warrants	517,435	60,801	49,994
Denominator for diluted earnings per share - adjusted weighted average shares	89,614,205	62,171,590	61,985,422
Basic	$ 1.95	$ 1.57	$ 1.45
Diluted	$ 1.93	$ 1.56	$ 1.43

EARNINGS PER COMMON SHARE - Add

EARNINGS PER COMMON SHARE - Additional Information (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share Disclosure [Line Items]
Investment Warrants, Exercise Price	$ 12.12
Preferred Stock, Shares Outstanding	0	0	0
Preferred Stock, Shares Authorized	10,000,000	10,000,000
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	0
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		104,200	114,678
MainSource [Member]
Earnings Per Share Disclosure [Line Items]
Investment Warrants, Exercise Price	$ 10.62
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	804,858

FAIR VALUE DISCLOSURES - Estima

FAIR VALUE DISCLOSURES - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financial assets
Investment securities held-to-maturity	$ 429,328	$ 654,008
Other investments	115,660	53,140
Deposits
Noninterest-bearing	2,492,434	1,662,058
Savings	3,167,325	2,462,420
Time	2,173,564	1,317,105
Total deposits	10,140,394	6,895,046
Carrying value
Financial assets
Cash and short-term investments	273,959	184,624
Investment securities held-to-maturity	429,328	654,008
Other investments	115,660	53,140
Loans held for sale	4,372	11,502
Loans and leases, net of ALLL	8,767,672	5,959,162
Interest Receivable	41,816	24,496
Deposits
Noninterest-bearing	2,492,434	1,662,058
Interest-bearing demand	2,307,071	1,453,463
Savings	3,167,325	2,462,420
Time	2,173,564	1,317,105
Total deposits	10,140,394	6,895,046
Short-term borrowings	1,040,691	814,565
Long-term debt	570,739	119,654
Interest Payable	12,126	5,104
Fair value
Financial assets
Cash and short-term investments	273,959	184,624
Investment securities held-to-maturity	424,118	653,101
Loans held for sale	4,372	11,502
Loans and leases, net of ALLL	8,662,868	6,006,656
Interest Receivable	41,816	24,496
Deposits
Noninterest-bearing	2,492,434	1,662,058
Interest-bearing demand	2,307,071	1,453,463
Savings	3,167,325	2,462,420
Time	2,146,645	1,306,674
Total deposits	10,113,475	6,884,615
Short-term borrowings	1,040,691	814,565
Long-term debt	557,933	117,908
Interest Payable	12,126	5,104
Fair Value, Inputs, Level 1 [Member] \| Fair value
Financial assets
Cash and short-term investments	273,959	184,624
Investment securities held-to-maturity	0	0
Loans held for sale	0	0
Loans and leases, net of ALLL	0	0
Interest Receivable	0	0
Deposits
Noninterest-bearing	0	0
Interest-bearing demand	0	0
Savings	0	0
Time	0	0
Total deposits	0	0
Short-term borrowings	1,040,691	814,565
Long-term debt	0	0
Interest Payable	2,035	204
Fair Value, Inputs, Level 2 [Member] \| Fair value
Financial assets
Cash and short-term investments	0	0
Investment securities held-to-maturity	424,118	653,101
Loans held for sale	4,372	11,502
Loans and leases, net of ALLL	0	0
Interest Receivable	13,819	8,265
Deposits
Noninterest-bearing	2,492,434	1,662,058
Interest-bearing demand	2,307,071	1,453,463
Savings	3,167,325	2,462,420
Time	2,146,645	1,306,674
Total deposits	10,113,475	6,884,615
Short-term borrowings	0	0
Long-term debt	557,933	117,908
Interest Payable	10,091	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, net of ALLL	8,662,868	6,006,656
Interest Receivable	27,997	16,231
Deposits
Noninterest-bearing	0	0
Interest-bearing demand	0	0
Savings	0	0
Time	0	0
Total 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 (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets
Derivatives	$ 29,189	$ 12,682
Investment securities, available for sale	2,779,255	1,349,408
Liabilities
Derivatives	29,188	12,687
Fair Value, Measurements, Recurring
Assets
Derivatives	29,543	12,757
Investment securities, available for sale	2,779,255	1,349,408
Total	2,808,798	1,362,165
Liabilities
Derivatives	29,336	12,755
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 1 [Member]
Assets
Derivatives	0	0
Investment securities, available for sale	97	2,969
Total	97	2,969
Liabilities
Derivatives	0	0
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 [Member]
Assets
Derivatives	29,543	12,757
Investment securities, available for sale	2,779,158	1,346,439
Total	2,808,701	1,359,196
Liabilities
Derivatives	29,336	12,755
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 3 [Member]
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 (Detail) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Inputs, Level 1 [Member]
Assets
Impaired loans	$ 0	$ 0
Other Real Estate Owned, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member]
Assets
Impaired loans	0	0
Other Real Estate Owned, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member]
Assets
Impaired loans	1,320	2,671
Other Real Estate Owned, Fair Value Disclosure	$ 1,089	$ 1,086

BUSINESS COMBINATIONS - Additio

BUSINESS COMBINATIONS - Additional Information - Narrative (Details) - USD ($) $ in Thousands	Apr. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Business Acquisition, Number Of Shares Received by Acquiree	1.3875
Business Combination, Consideration Transferred	$ 1,100,000	$ 1,059,504
Goodwill		676,167	$ 0	$ 0
Payments for Merger Related Costs		37,800
Loans	2,800,000	$ 2,792,740
Business Combination, Acquired Receivables, Gross Contractual Amount	$ 2,900,000

BUSINESS COMBINATION BUSINESS C

BUSINESS COMBINATION BUSINESS COMBINATIONS (Details) - USD ($) $ in Thousands	Apr. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Cash consideration		$ 43
Stock consideration		1,043,424
Warrant consideration		14,460
Options consideration		1,577
Total purchase consideration	$ 1,100,000	1,059,504
Cash		71,688
Investment securities available-for-sale		900,935
Investment securities held-to-maturity		171,423
Other investments		28,763
Loans	$ 2,800,000	2,792,740
Premises and equipment		98,381
Intangible assets		42,887
Other assets		167,693
Assets held for sale		127,775
Total assets acquired		4,402,285
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	$ 0
Net identifiable assets		383,337
Goodwill		$ 676,167	$ 0	$ 0

BUSINESS COMBINATION BUSINESS_2

BUSINESS COMBINATION BUSINESS COMBINATIONS - Pro Forma Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Combinations [Abstract]
Business Acquisition, Pro Forma Revenue	$ 484,915	$ 454,579
Business Acquisition, Pro Forma Net Income	$ 221,122	$ 130,402
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 2.27	$ 1.34
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 2.25	$ 1.33

FIRST FINANCIAL BANCORP. (PAR_3

FIRST FINANCIAL BANCORP. (PARENT COMPANY ONLY) FINANCIAL INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Cash	$ 150,650	$ 121,598	$ 114,841	$ 236,221	$ 150,650	$ 121,598	$ 114,841
Investment securities, available for sale				2,779,255	1,349,408
Other investments				115,660	53,140
Premises and equipment				215,652	125,036
Total assets				13,986,660	8,896,923
Subordinated Debt				170,550	120,000
Other liabilities				156,587	136,994
Total liabilities				11,908,411	7,966,259
Shareholders’ equity				2,078,249	930,664	865,224	809,376
Total liabilities and shareholders’ equity				13,986,660	8,896,923
Income Statement [Abstract]
Noninterest income	103,382	76,142	69,601
Interest Expense	91,147	49,528	33,279
Salaries and employee benefits	188,990	137,240	128,549
Miscellaneous professional services	12,272	15,023	6,303
Income before income taxes and equity in undistributed net earnings of subsidiaries	214,221	116,163	130,731
Income tax expense (benefit)	41,626	19,376	42,205
Net income	172,595	96,787	88,526
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	153,670	104,840	90,663
Operating activities
Net income	172,595	96,787	88,526
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	24,171	12,645	13,037
Stock-based compensation expense	6,219	5,446	5,354
Deferred income taxes	6,267	(4,488)	346
Decrease (increase) in other assets	34,360	(21,455)	(1,108)
Net cash provided by (used in) operating activities	261,398	123,524	142,600
Investing activities
Proceeds from calls and maturities of investment securities	387,351	224,690	186,132
Purchases of investment securities	(852,131)	(723,131)	(396,984)
Net cash provided by (used in) investing activities	(205,837)	(429,452)	(313,348)
Financing activities
Net (decrease) increase in short-term borrowings	30,531	6,653	(130,513)
Cash dividends paid on common stock	(79,655)	(41,178)	(39,125)
Proceeds from exercise of stock options, net of shares purchased	284	341	801
Excess tax benefit on share-based compensation	0	0	264
Net cash provided by (used in) financing activities	30,010	334,980	177,505
Net increase (decrease) in cash	85,571	29,052	6,757
Cash and due from banks at beginning of year	150,650	121,598	114,841
Cash and due from banks at end of year	236,221	150,650	121,598
Parent Company [Member]
Statement of Financial Position [Abstract]
Cash	57,719	59,285	106,072	86,878	57,719	$ 59,285	$ 106,072
Investment securities, available for sale				694	442
Subordinated notes from subsidiaries				7,500	7,500
Investment in subsidiaries				2,085,849	970,290
Premises and equipment				1,361	1,378
Other assets				71,817	26,778
Total assets				2,254,099	1,064,107
Subordinated Debt				171,416	118,638
Dividends payable				465	10,965
Other liabilities				3,969	3,840
Total liabilities				175,850	133,443
Shareholders’ equity				2,078,249	930,664
Total liabilities and shareholders’ equity				2,254,099	1,064,107
Income Statement [Abstract]
Interest income	23	6	48
Noninterest income	0	86	2,596
Dividends from subsidiaries	107,340	54,600	52,700
Total income	107,363	54,692	55,344
Interest Expense	8,798	6,152	6,151
Salaries and employee benefits	6,413	5,519	5,445
Miscellaneous professional services	5,130	970	711
Other	5,648	4,819	4,841
Total expenses	25,989	17,460	17,148
Income before income taxes and equity in undistributed net earnings of subsidiaries	81,374	37,232	38,196
Income tax expense (benefit)	(6,687)	(7,080)	(5,302)
Equity in undistributed earnings (loss) of subsidiaries	(84,534)	(52,475)	(45,028)
Net income	172,595	96,787	88,526
Operating activities
Net income	172,595	96,787	88,526
Adjustments to reconcile net income to net cash provided by operating activities
Equity in undistributed earnings (loss) of subsidiaries	(84,534)	(52,475)	(45,028)
Depreciation and amortization	194	193	192
Stock-based compensation expense	6,219	5,446	5,354
Deferred income taxes	739	(360)	584
(Decrease) increase in dividends payable	(10,500)	579	135
Increase (decrease) in other liabilities	9,979	(889)	(389)
Decrease (increase) in other assets	16,346	(6,951)	(9,065)
Net cash provided by (used in) operating activities	111,038	42,330	40,309
Investing activities
Capital contributions to subsidiaries	(3,000)	0	(53,000)
Net cash acquired (paid) from business combinations	11,353	0	0
Proceeds from calls and maturities of investment securities	0	0	5,978
Purchases of investment securities	0	0	(333)
Net cash provided by (used in) investing activities	8,353	0	(47,355)
Financing activities
Net (decrease) increase in short-term borrowings	(8,333)	0	0
Cash dividends paid on common stock	(79,655)	(41,178)	(39,125)
Proceeds from exercise of stock options, net of shares purchased	284	341	801
Excess tax benefit on share-based compensation	0	0	264
Other	(2,528)	(3,059)	(1,681)
Net cash provided by (used in) financing activities	(90,232)	(43,896)	(39,741)
Net increase (decrease) in cash	29,159	(1,566)	(46,787)
Cash and due from banks at beginning of year	57,719	59,285	106,072
Cash and due from banks at end of year	$ 86,878	$ 57,719	$ 59,285
Parent Company [Member] \| Commercial Banks [Member]
Statement of Financial Position [Abstract]
Investment in subsidiaries				2,078,655	970,290
Parent Company [Member] \| Nonbanks [Member]
Statement of Financial Position [Abstract]
Investment in subsidiaries				$ 7,194	$ 0