First Financial Bancorp. (FFBC) 10-K 21 Feb 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Document - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 20, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-34762
Entity Registrant Name	FIRST FINANCIAL BANCORP.
Entity Incorporation, State or Country Code	OH
Entity Tax Identification Number	31-1042001
Entity address line two	255 East Fifth Street, Suite 800
Entity Address, City or Town	Cincinnati
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45202
City Area Code	877
Local Phone Number	322-9530
Title of 12(g) Security	None
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 2,341,389,000
Entity Common Stock, Shares Outstanding		98,490,998
Entity Central Index Key	0000708955
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
NASDAQ/NMS (GLOBAL MARKET) [Member]
Entity Listings [Line Items]
Title of 12(b) Security	Common stock, No par value
Trading Symbol	FFBC
Security Exchange Name	NASDAQ

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
ASSETS
Cash and due from banks	$ 200,691	$ 236,221
Interest-bearing deposits with other banks	56,948	37,738
Investment securities available-for-sale, at fair value (amortized cost $2,798,298 at December 31, 2019 and $2,792,326 at December 31, 2018)	2,852,084	2,779,255
Investment securities held-to-maturity (fair value $142,821 at December 31, 2019 and $424,118 at December 31, 2018)	142,862	429,328
Other investments	125,020	115,660
Loans held for sale	13,680	4,372
Loans and leases
Total loans and leases	9,201,665	8,824,214
Loans and Leases Receivable, Allowance	57,650	56,542
Net loans and leases	9,144,015	8,767,672
Premises and equipment	214,506	215,652
Goodwill	937,771	880,251
Other intangibles	76,201	40,805
Accrued interest and other assets	747,847	479,706
Deposits
Interest-bearing demand	2,364,881	2,307,071
Savings	2,960,979	3,167,325
Time	2,240,441	2,173,564
Total interest-bearing deposits	7,566,301	7,647,960
Total assets	14,511,625	13,986,660
Noninterest-bearing	2,643,928	2,492,434
Total deposits	10,210,229	10,140,394
Federal funds purchased and securities sold under agreements to repurchase	165,181	183,591
FHLB short-term borrowings	1,151,000	857,100
Total short-term borrowings	1,316,181	1,040,691
Long-term debt	414,376	570,739
Total borrowed funds	1,730,557	1,611,430
Accrued interest and other liabilities	323,134	156,587
Total liabilities	12,263,920	11,908,411
Shareholders' equity
Common stock - no par value	1,640,771	1,633,256
Retained earnings	711,249	600,014
Accumulated other comprehensive income (loss)	13,323	(44,408)
Treasury stock, at cost, 5,790,796 shares in 2019 and 6,387,508 shares in 2018	(117,638)	(110,613)
Total shareholders' equity	2,247,705	2,078,249
Total liabilities and shareholders’ equity	14,511,625	13,986,660
Commercial & industrial
Loans and leases
Total loans and leases	2,465,877	2,514,661
Lease financing
Loans and leases
Total loans and leases	88,364	93,415
Construction real estate
Loans and leases
Total loans and leases	493,182	548,935
Commercial real estate
Loans and leases
Total loans and leases	4,194,651	3,754,681
Residential real estate
Loans and leases
Total loans and leases	1,055,949	955,646
Home equity
Loans and leases
Total loans and leases	771,869	817,282
Installment
Loans and leases
Total loans and leases	82,589	93,212
Credit card
Loans and leases
Total loans and leases	$ 49,184	$ 46,382

CONSOLIDATED BALANCE SHEETS CON

CONSOLIDATED BALANCE SHEETS CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Investment securities available-for-sale, cost	$ 2,798,298	$ 2,792,326
Investment securities held-to-maturity, market value	$ 142,821	$ 424,118
Common Stock, No Par Value	$ 0	$ 0
Common Stock, Shares Authorized	160,000,000	160,000,000
Common Stock, Shares, Issued	104,281,794	104,281,794
Treasury Stock, Shares	5,790,796	6,387,508

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Intangible assets amortization	$ 9,671	$ 7,359	$ 1,298
Interest income
Loans and leases, including fees	499,009	447,187	280,111
Investment securities
Taxable	90,168	79,076	50,568
Tax-exempt	17,596	13,428	5,918
Total interest on investment securities	107,764	92,504	56,486
Other earning assets	805	691	(3,524)
Total interest income	607,578	540,382	333,073
Interest expense
Deposits	79,032	56,962	35,182
Short-term borrowings	25,235	18,033	8,193
Long-term borrowings	19,057	16,152	6,153
Total interest expense	123,324	91,147	49,528
Net interest income	484,254	449,235	283,545
Provision for loan and lease losses	30,598	14,586	3,582
Net interest income after provision for loan and lease losses	453,656	434,649	279,963
Noninterest income
Service charges on deposit accounts	37,939	35,108	19,775
Investment Banking, Advisory, Brokerage, and Underwriting Fees and Commissions	15,644	15,082	14,073
Bankcard income	18,804	20,245	13,298
Client derivative fees	15,662	7,682	6,418
Foreign exchange income	7,739	0	0
Net gain from sales of loans	14,851	6,071	5,169
Net gain (loss) on sales/transfers of investment securities	(406)	(161)	1,649
Other	21,140	19,355	15,760
Total noninterest income	131,373	103,382	76,142
Noninterest expenses
Salaries and employee benefits	209,061	188,990	137,240
Net occupancy	24,069	24,215	17,397
Furniture and equipment	15,903	14,908	8,443
Data processing	21,881	28,077	14,022
Marketing	6,908	7,598	3,201
Communication	3,267	3,167	1,819
Professional services	11,254	12,272	15,023
State intangible tax	5,829	4,152	2,655
FDIC assessments	1,973	3,969	3,944
Other	32,351	29,103	34,900
Total noninterest expenses	342,167	323,810	239,942
Income before income taxes	242,862	214,221	116,163
Income tax expense	44,787	41,626	19,376
Net income	$ 198,075	$ 172,595	$ 96,787
Earnings per common share
Basic	$ 2.01	$ 1.95	$ 1.57
Diluted	$ 2	$ 1.93	$ 1.56
Average common shares outstanding - basic	98,305,570	88,582,090	61,529,460
Average common shares outstanding - diluted	98,851,471	89,614,205	62,171,590

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 198,075	$ 172,595	$ 96,787
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on debt securities arising during the period	51,959	(11,229)	4,367
Change in retirement obligation	4,649	(8,180)	3,172
Unrealized gain (loss) on derivatives	217	484	514
Other comprehensive income (loss)	56,825	(18,925)	8,053
Comprehensive income	$ 254,900	$ 153,670	$ 104,840

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, 2017 at Dec. 31, 2016	$ 865,224	$ 570,382	$ 437,188	$ (28,443)	$ (113,903)
Balances at January 1, 2017 at Dec. 31, 2016		68,730,731			(6,751,179)
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 $0.90 per share in 2019, $0.76 per share in 2018, and $0.68 per share in 2017	(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			5,093	(5,093)
Net income	172,595		172,595
Other comprehensive loss	(18,925)			(18,925)
Cash dividends declared:
Common stock at $0.90 per share in 2019, $0.76 per share in 2018, and $0.68 per share in 2017	(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	0
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
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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	3,542		2,636	906
Net income	198,075		198,075
Other comprehensive loss	56,825			56,825
Cash dividends declared:
Common stock at $0.90 per share in 2019, $0.76 per share in 2018, and $0.68 per share in 2017	(89,476)		(89,476)
Stock Issued During Period, Shares, Acquisitions					2,601,823
Common stock issued in connection with business combinations	$ 60,934	13,658			$ 47,276
Treasury Stock, Shares, Acquired	(2,753,272)				(2,753,272)
Treasury Stock, Value, Acquired, Cost Method	$ (66,218)				$ (66,218)
Adjustments to Additional Paid in Capital, Other	$ 0	(7,830)			$ 7,830
Stock Issued During Period, Shares, Other					452,134
Exercise of stock options, net of shares purchased (in shares)	24,554				20,424
Exercise of stock options, net of shares purchased	$ 90	264			$ 354
Restricted stock awards, net of forfeitures (in shares)					275,603
Restricted stock awards, net of forfeitures	(2,285)	(6,018)			$ 3,733
Share-based compensation expense	7,969	$ 7,969
Ending Balances (in shares) at Dec. 31, 2019		104,281,794			(5,790,796)
Ending Balances at Dec. 31, 2019	$ 2,247,705	$ 1,640,771	$ 711,249	$ 13,323	$ (117,638)

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Stock, Dividends, Per Share, Declared	$ 0.90	$ 0.78	$ 0.68

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net income	$ 198,075	$ 172,595	$ 96,787
Adjustments to reconcile net income to net cash provided by operating activities
Provision for loan and lease losses	30,598	14,586	3,582
Depreciation and amortization	28,138	24,171	12,645
Stock-based compensation expense	7,969	6,219	5,446
Pension expense (income)	1,041	859	(628)
Net amortization (accretion) on investment securities	11,430	10,846	10,798
Net (gains) losses on sales of investments securities	406	161	(1,649)
Originations of loans held for sale	(390,578)	(157,771)	(157,796)
Net (gains) losses on sales of loans held for sale	(14,851)	(6,071)	(5,169)
Proceeds from sales of loans held for sale	396,121	167,374	163,300
Deferred income taxes	12,590	6,267	(4,488)
Operating Lease, Expense	7,324	0	0
Operating Lease, Payments	(7,335)	0	0
Life Insurance, Corporate or Bank Owned, Change in Value	3,748	5,454	3,792
Decrease (increase) in interest receivable	2,117	(3,808)	(5,707)
Increase (Decrease) in Other Receivables	0	(1,900)	(10,117)
(Decrease) increase in interest payable	1,545	5,207	55
Decrease (increase) in other assets	(166,477)	34,360	(21,455)
(Decrease) increase in other liabilities	71,964	(10,043)	21,478
Net cash provided by (used in) operating activities	186,329	261,398	123,524
Investing activities
Proceeds from sales of investment securities available-for-sale	519,136	290,745	189,962
Proceeds from calls, paydowns and maturities of securities available-for-sale	557,034	387,351	224,690
Purchases of securities available-for-sale	(834,743)	(852,131)	(723,131)
Proceeds from calls, paydowns and maturities of securities held-to-maturity	18,062	36,671	121,903
Purchases of securities held-to-maturity	0	(14,014)	(23,402)
Purchases of other investment securities	(12,120)	(31,385)	(2,353)
Net decrease (increase) in interest-bearing deposits with other banks	(19,210)	(3,764)	48,476
Net decrease (increase) in loans and leases	(409,557)	(28,577)	(266,043)
Proceeds from Sale of Other Real Estate	1,453	3,797	6,983
Purchases of premises and equipment	(20,934)	(18,228)	(6,537)
Net cash acquired (paid) in business combinations	(51,663)		0
Cash Acquired from Acquisition		64,895
Payments for (Proceeds from) Businesses and Interest in Affiliates	118	(41,197)	0
Net cash provided by (used in) investing activities	(252,424)	(205,837)	(429,452)
Financing activities
Net (decrease) increase in total deposits	69,953	(18,690)	369,258
Net (decrease) increase in short-term borrowings	275,490	30,531	6,653
Payments on long-term borrowings	(159,653)	(52,460)	(94)
Proceeds from FHLBank Borrowings, Financing Activities	0	150,000	0
Cash dividends paid on common stock	(89,097)	(79,655)	(41,178)
Treasury stock purchase	(66,218)	0	0
Proceeds from exercise of stock options	90	284	341
Net cash provided by (used in) financing activities	30,565	30,010	334,980
Cash and due from banks
Net (decrease) increase in Cash and due from banks	(35,530)	85,571	29,052
Cash and due from banks at beginning of year	236,221	150,650	121,598
Cash and due from banks at end of year	200,691	236,221	150,650
Supplemental disclosures
Interest paid	121,779	84,125	49,474
Income taxes paid	27,497	16,004	38,329
Acquisition of other real estate owned through foreclosure	2,448	3,182	4,119
Real Estate Owned, Transfer to Real Estate Owned excluding acquired OREO		1,821
Issuance of restricted stock awards	10,488	8,797	6,416
Securities transferred from HTM to AFS	268,703	372,128	0
Common stock issued in bank acquisitions	60,934	1,043,424	0
Initial recognition of operating lease right of use asset	58,600	0	0
Initial recognition of operating lease liabilities	64,277	0	0
Supplemental schedule for investing activities
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Assets, Net Of Purchase Consideration	(39,140)	3,342,781	0
Total liabilities assumed	18,380	4,018,948	0
Goodwill	$ 57,520	$ 676,167	$ 0

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Notes)	12 Months Ended
	Dec. 31, 2019
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 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 balances that are on deposit at other depository institutions. 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 also 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 and FHLB stock, which are both carried at cost, in addition to equity securities which are carried at fair value. Changes in the fair value of equity securities are recorded in 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 held for sale 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). 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. Management evaluates Commercial loan and lease relationships greater than $250,000 that are considered impaired, or designated as a TDR to determine the need for a specific allowance. This evaluation is 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 delinquent and nonaccrual loans, prevailing economic conditions and changes in lending strategies, among other influencing factors. Consumer loans generally exhibit homogeneous characteristics and are evaluated by loan type. 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. An allowance for loan losses will be established for any subsequent credit deterioration or adverse changes in expected cash flows. 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 other intangible assets deemed to have indefinite lives 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. Other intangible assets. Other intangible assets consist primarily of core deposit, customer list and other miscellaneous 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. First Financial recorded a customer list intangible asset in conjunction with the Bannockburn merger to account for the obligation or advantage on the part of either the Company or the customer to continue the pre-existing relationship subsequent to the merger. The customer list intangible asset is amortized on a straight-line basis over its estimated useful life. Other miscellaneous intangibles include purchase commissions, non-compete agreements and trade name intangibles. Other intangible assets are included in Other intangibles in the Consolidated Balance Sheets. 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 included in Accrued interest and other assets in the Consolidated Balance Sheets and are accounted for under the proportional amortization method. Under the proportional amortization method, the initial cost of the investment is amortized in proportion to the tax credits and other benefits received and recognized as a component of Income tax expense in the Consolidated Statements of Income. 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. For historic tax credits, impairment is recorded in Other noninterest expense. The tax credit and other net tax benefits received are recognized as a component of income tax expense in the Consolidated Statements of Income. 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 recorded in Other 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 matched 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. First Financial may enter into foreign exchange derivative contracts for the benefit of commercial customers to hedge their exposure to foreign currency fluctuations. Similar to the hedging of interest rate risk from interest rate derivative contracts, First Financial also enters into foreign exchange contracts with major financial institutions to economically hedge a substantial portion of the exposure from client driven foreign exchange activity. These derivatives are classified as free-standing instruments with the revaluation gain or loss recorded in Foreign exchange income in the Consolidated Statements of Income. 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
	Dec. 31, 2019
Accounting Policies [Abstract]
RECENTLY ADOPTED AND ISSUED ACCOUNTING STANDARDS	Accounting Standards Recently Adopted or Issued Standards Adopted in 2019 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 where the Company is the lessee, except for short-term leases that are subject to an accounting policy election, were recorded on the balance sheet by establishing a lease liability and corresponding ROU asset. All entities are required to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. As the Company elected the transition option provided in ASU No. 2018-11, the modified retrospective approach was applied on January 1, 2019 (as opposed to January 1, 2017). The Company also elected certain relief options offered in ASU 2016-02 including the package of practical expedients, the option not to separate lease and non-lease components and instead to account for them as a single lease component and the option not to recognize ROU assets and lease liabilities that arise from short-term leases. The Company did not elect the hindsight practical expedient, which allows entities to use hindsight when determining lease term and impairment of ROU assets. The guidance in this ASU became effective January 1, 2019 at which time the Company recorded on the Consolidated Balance Sheet an ROU asset of $60.2 million and a lease liability of $65.8 million . For further detail, see Note 7 – Leases. 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 became effective at the beginning of 2019 but 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 became effective January 1, 2019. Upon adoption, the Company reclassified $268.7 million of HTM securities to AFS, resulting in a $0.2 million loss in the Consolidated Statement of Income. Standards Issued But Not Yet Adopted 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, commonly known as CECL, 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 economic forecasts, when developing expected credit loss estimates. This update also expands the disclosure requirements regarding an entity’s assumptions, models and methods for estimating the ACL, including the disclosure of the amortized cost balance for each class of financial asset by credit quality indicator, disaggregated by the year of origination. In addition to the new framework for calculating the ACL, 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. The guidance in this ASU will become effective for interim and annual reporting periods beginning after December 15, 2019. As of January 1, 2020, First Financial expects to recognize a one-time cumulative effect adjustment to increase the ACL with an offsetting reduction to the retained earnings component of equity. In December 2018, the federal bank regulatory agencies approved a final rule that modifies their regulatory capital rules and provides institutions the option to phase in over a three-year period any day-one regulatory capital effects of this update. First Financial expects to adopt the regulatory phase-in over the permissible three-year period. First Financial formed a cross-functional internal management committee and engaged a third party vendor to assist with the transition to the guidance set forth in this update. The new allowance model implemented by First Financial estimates credit losses over the expected life of the portfolio and includes a qualitative framework to account for the drivers of losses that are not captured by the quantitative model. Based upon preliminary modeling results, management estimates that the reserve will increase to between $115.0 million and $125.0 million upon adoption of this ASU. The expected increase in the ACL is significantly impacted by the number of previously acquired loans with credit discounts, the credit losses expected over the life of the portfolio and management's consideration of future economic conditions. The actual impact from adopting this guidance may be subject to change based upon refinement and finalization of the model and associated assumptions, the implementation and testing of certain internal controls ensuring model effectiveness and management’s judgment. In addition, the adoption of this ASU may result in a more volatile provision for credit losses in future periods. Management expects the ACL for unfunded commitments to increase to $11.0 million to $14.0 million upon adoption. First Financial does not expect a material allowance for credit losses on HTM securities as a result of guidance set forth in this update given the size and composition of the portfolio, which primarily includes government agency backed securities. In addition, the Company does not expect a material loss on AFS debt securities. In August 2018, the FASB issued an update (ASU No. 2018-13, Disclosure Framework: Changes to the Disclosure Requirements for Fair Value Measurement) which eliminates, adds and modifies certain disclosure requirements for fair value measurements. Under the changes, entities will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, but will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. The update is effective for interim and annual reporting periods beginning after December 15, 2019, and early adoption is permitted. This update is not expected to have a material impact on the Company’s Consolidated Financial Statements.

RESTRICTIONS ON CASH AND DIVIDE

RESTRICTIONS ON CASH AND DIVIDENDS	12 Months Ended
	Dec. 31, 2019
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 $84.1 million and $85.9 million for 2019 and 2018 , respectively. Additionally, as of December 31, 2019 , First Financial had $15.8 million in cash restricted for withdrawal and usage due to the centrally cleared derivative initial margin requirement. 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, 2019 , First Financial's subsidiaries had retained earnings of $660.7 million , of which $155.7 million was available for distribution to First Financial without prior regulatory approval.

INVESTMENTS

INVESTMENTS	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
INVESTMENTS	Investment Securities During the year ended December 31, 2019 , proceeds on the sale of $519.1 million of AFS securities resulted in gains of $2.1 million and losses of $2.1 million , with insignificant tax expense. 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 , losses of $0.6 million and 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 in addition to tax expense of $0.6 million . In addition to the sale of certain securities, First Financial reclassified $268.7 million of HTM securities, in conjunction with the adoption of ASU 2017-12 in the first quarter of 2019, resulting in a $0.2 million realized loss recorded in the Consolidated Statement of Income. To align with post-merger investment strategies, during the second quarter 2018 First Financial sold certain securities and reclassified $372.1 million of HTM securities to AFS . The carrying value of investment securities pledged as collateral to secure public deposits, repurchase agreements and for other purposes as required by law totaled $1.1 billion at December 31, 2019 and $1.2 billion at December 31, 2018 . The following is a summary of HTM and AFS investment securities as of December 31, 2019 : 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 $ 1 $ 0 $ 100 Securities of U.S. government agencies and corporations 0 0 0 0 156 2 0 158 Mortgage-backed securities - residential 20,818 122 (174 ) 20,766 421,945 9,709 (99 ) 431,555 Mortgage-backed securities - commercial 101,267 571 (1,225 ) 100,613 474,174 4,988 (2,644 ) 476,518 Collateralized mortgage obligations 9,763 0 (108 ) 9,655 769,076 16,753 (385 ) 785,444 Obligations of state and other political subdivisions 11,014 804 (31 ) 11,787 652,986 23,729 (462 ) 676,253 Asset-backed securities 0 0 0 0 400,081 1,414 (1,064 ) 400,431 Other securities 0 0 0 0 79,781 1,959 (115 ) 81,625 Total $ 142,862 $ 1,497 $ (1,538 ) $ 142,821 $ 2,798,298 $ 58,555 $ (4,769 ) $ 2,852,084 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 Unrecognized Unrecognized Fair Amortized Unrealized Unrealized Fair 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 table provides a summary of investment securities by contractual maturity as of December 31, 2019 , 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 $ 7,382 $ 7,408 Due after one year through five years 0 0 52,075 53,189 Due after five years through ten years 4,756 5,417 144,626 149,961 Due after ten years 6,258 6,370 528,939 547,578 Mortgage-backed securities - residential 20,818 20,766 421,945 431,555 Mortgage-backed securities - commercial 101,267 100,613 474,174 476,518 Collateralized mortgage obligations 9,763 9,655 769,076 785,444 Asset-backed securities 0 0 400,081 400,431 Total $ 142,862 $ 142,821 $ 2,798,298 $ 2,852,084 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, 2019 , 2018 or 2017. As of December 31, 2019 , the Company's investment securities portfolio consisted of 1,273 securities, of which 140 securities were in an unrealized loss position. As of December 31, 2018, the Company's investment securities portfolio consisted of 1,417 securities, of which 504 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, 2019 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 $ 0 $ 0 $ 0 $ 0 Securities of U.S. government agencies and corporations 0 0 0 0 0 0 Mortgage-backed securities - residential 40,190 (209 ) 11,063 (64 ) 51,253 (273 ) Mortgage-backed securities - commercial 111,658 (298 ) 104,069 (3,571 ) 215,727 (3,869 ) Collateralized mortgage obligations 85,248 (297 ) 30,628 (196 ) 115,876 (493 ) Obligations of state and other political subdivisions 118,623 (457 ) 7,950 (36 ) 126,573 (493 ) Asset-backed securities 125,889 (553 ) 54,963 (511 ) 180,852 (1,064 ) Other securities 0 0 5,649 (115 ) 5,649 (115 ) Total $ 481,608 $ (1,814 ) $ 214,322 $ (4,493 ) $ 695,930 $ (6,307 ) December 31, 2018 Less than 12 months 12 months or more Total (Dollars in thousands) Fair Unrealized Fair Unrealized Fair Unrealized 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 ) For further detail on the fair value of investment securities, see Note 22 – Fair Value Disclosures.

LOANS

LOANS	12 Months Ended
	Dec. 31, 2019
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, 2019 Real Estate (Dollars in thousands) Commercial & industrial Construction Commercial Lease financing Total Pass $ 2,324,021 $ 493,182 $ 4,108,752 $ 85,262 $ 7,011,217 Special Mention 100,954 0 59,383 488 160,825 Substandard 40,902 0 26,516 2,614 70,032 Doubtful 0 0 0 0 0 Total $ 2,465,877 $ 493,182 $ 4,194,651 $ 88,364 $ 7,242,074 Residential real estate Home equity Installment Credit card Total Performing $ 1,040,787 $ 766,169 $ 82,385 $ 48,983 $ 1,938,324 Nonperforming 15,162 5,700 204 201 21,267 Total $ 1,055,949 $ 771,869 $ 82,589 $ 49,184 $ 1,959,591 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 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, 2019 (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 $ 1,266 $ 3,332 $ 14,518 $ 19,116 $ 2,443,680 $ 2,462,796 $ 3,081 $ 2,465,877 $ 0 Lease financing 0 0 0 0 88,364 88,364 0 88,364 0 Construction real estate 0 0 0 0 493,167 493,167 15 493,182 0 Commercial real estate 776 857 5,613 7,246 4,151,513 4,158,759 35,892 4,194,651 0 Residential real estate 8,032 1,928 5,031 14,991 1,014,138 1,029,129 26,820 1,055,949 0 Home equity 2,530 1,083 2,795 6,408 762,863 769,271 2,598 771,869 0 Installment 111 50 148 309 82,022 82,331 258 82,589 0 Credit card 208 75 201 484 48,700 49,184 0 49,184 201 Total $ 12,923 $ 7,325 $ 28,306 $ 48,554 $ 9,084,447 $ 9,133,001 $ 68,664 $ 9,201,665 $ 201 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 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 157 TDRs totaling $30.0 million at December 31, 2019 , including $11.4 million of loans on accrual status and $18.5 million of loans classified as nonaccrual. First Financial had $2.5 million commitments outstanding to lend additional funds to borrowers whose loan terms had been modified through TDRs, and the ALLL included reserves of $2.5 million related to TDRs as of December 31, 2019 . For the years ended December 31, 2019 , 2018 and 2017 , First Financial charged off $2.6 million , $0.9 million and $0.3 million , respectively, for the portion of TDRs determined to be uncollectible. Additionally, as of December 31, 2019 , approximately $4.7 million of the accruing TDRs have been performing in accordance with the restructured terms for more than one year. 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 had been modified through TDRs. At December 31, 2018 the ALLL included reserves of $1.5 million related to TDRs, and $7.9 million of the accruing TDRs had 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 had been modified through TDRs. At December 31, 2017 , the ALLL included reserves of $1.3 million related to TDRs, and $17.2 million of the accruing TDRs had been performing in accordance with the restructured terms for more than one year. The following table provides information on loan modifications classified as TDRs during the years ended December 31, 2019 , 2018 and 2017 : Years ended December 31, 2019 2018 2017 (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 8 $ 25,009 $ 25,071 17 $ 23,943 $ 23,890 7 $ 5,724 $ 5,661 Construction real estate 0 0 0 0 0 0 0 0 0 Commercial real estate 9 3,024 2,932 8 3,385 3,150 8 1,816 1,758 Residential real estate 30 3,415 3,062 13 1,148 1,073 6 416 315 Home equity 14 395 366 5 95 192 1 39 39 Installment 2 41 39 0 0 0 0 0 0 Total 63 $ 31,884 $ 31,470 43 $ 28,571 $ 28,305 22 $ 7,995 $ 7,773 The following table provides information on how TDRs were modified during the years ended December 31, 2019 , 2018 and 2017 : Years Ended December 31, (Dollars in thousands) 2019 2018 2017 Extended maturities $ 2,877 $ 4,093 $ 3,261 Adjusted interest rates 5,284 52 2,767 Combination of rate and maturity changes 516 0 489 Forbearance 20,320 23,175 1,181 Other (1) 2,473 985 75 Total $ 31,470 $ 28,305 $ 7,773 (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, are considered to be in payment default of the terms of the TDR agreement. For the twelve months ended December 31, 2019 , there were three TDRs with a balance of $7.0 million 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, 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 , there was one TDR with a balance $1.5 million 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) 2019 2018 2017 Impaired loans Nonaccrual loans (1) Commercial & industrial $ 24,346 $ 30,925 $ 5,229 Lease financing 223 22 82 Construction real estate 0 9 29 Commercial real estate 7,295 20,500 10,616 Residential real estate 10,892 13,495 4,140 Home equity 5,242 5,580 3,743 Installment 167 169 243 Total nonaccrual loans 48,165 70,700 24,082 Accruing troubled debt restructurings 11,435 16,109 17,545 Total impaired loans $ 59,600 $ 86,809 $ 41,627 Interest income effect Gross amount of interest that would have been recorded under original terms $ 5,813 $ 4,656 $ 3,397 Interest included in income Nonaccrual loans 1,042 715 535 Troubled debt restructurings 801 642 710 Total interest included in income 1,843 1,357 1,245 Net impact on interest income $ 3,970 $ 3,299 $ 2,152 Commitments outstanding to borrowers with nonaccrual loans $ 3 $ 200 $ 0 (1) Nonaccrual loans include nonaccrual TDRs of $18.5 million , $22.4 million and $6.4 million as of December 31, 2019 , 2018 and 2017 , 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, 2019 December 31, 2018 (Dollars in thousands) Current balance Contractual principal balance Related allowance Current balance Contractual Related Loans with no related allowance recorded Commercial & industrial $ 16,726 $ 19,709 $ 0 $ 36,694 $ 42,561 $ 0 Lease financing 223 223 0 22 22 0 Construction real estate 0 0 0 9 26 0 Commercial real estate 10,160 17,897 0 23,513 31,375 0 Residential real estate 14,868 17,368 0 17,297 19,975 0 Home equity 5,700 6,462 0 6,351 7,461 0 Installment 204 341 0 174 563 0 Total 47,881 62,000 0 84,060 101,983 0 Loans with an allowance recorded Commercial & industrial 10,754 21,513 2,044 939 939 667 Lease financing 0 0 0 0 0 0 Construction real estate 0 0 0 0 0 0 Commercial real estate 671 675 113 1,509 1,509 461 Residential real estate 294 294 18 301 301 32 Home equity 0 0 0 0 0 0 Installment 0 0 0 0 0 0 Total 11,719 22,482 2,175 2,749 2,749 1,160 Total Commercial & industrial 27,480 41,222 2,044 37,633 43,500 667 Lease financing 223 223 0 22 22 0 Construction real estate 0 0 0 9 26 0 Commercial real estate 10,831 18,572 113 25,022 32,884 461 Residential real estate 15,162 17,662 18 17,598 20,276 32 Home equity 5,700 6,462 0 6,351 7,461 0 Installment 204 341 0 174 563 0 Total $ 59,600 $ 84,482 $ 2,175 $ 86,809 $ 104,732 $ 1,160 Years ended December 31, 2019 2018 2017 (Dollars in thousands) Average balance Interest Average balance Interest income recognized Average Interest Loans with no related allowance recorded Commercial & industrial $ 31,846 $ 926 $ 14,498 $ 360 $ 13,167 $ 280 Lease financing 168 0 21 0 112 4 Construction real estate 6 0 20 2 601 1 Commercial real estate 18,757 357 24,738 490 20,935 563 Residential real estate 15,915 307 11,359 301 7,616 196 Home equity 5,893 121 5,541 114 4,032 99 Installment 170 2 274 2 332 4 Total 72,755 1,713 56,451 1,269 46,795 1,147 Loans with an allowance recorded Commercial & industrial 4,721 87 900 44 1,204 28 Lease financing 57 0 0 0 0 0 Construction real estate 0 0 0 0 0 0 Commercial real estate 1,339 31 1,402 18 2,634 40 Residential real estate 446 12 895 23 1,112 26 Home equity 0 0 80 3 101 4 Installment 0 0 0 0 0 0 Total 6,563 130 3,277 88 5,051 98 Total Commercial & industrial 36,567 1,013 15,398 404 14,371 308 Lease financing 225 0 21 0 112 4 Construction real estate 6 0 20 2 601 1 Commercial real estate 20,096 388 26,140 508 23,569 603 Residential real estate 16,361 319 12,254 324 8,728 222 Home equity 5,893 121 5,621 117 4,133 103 Installment 170 2 274 2 332 4 Total $ 79,318 $ 1,843 $ 59,728 $ 1,357 $ 51,846 $ 1,245 OREO. OREO is comprised of properties acquired by the Company primarily through the loan foreclosure or repossession process, that result in partial or total satisfaction of problem loans. Changes in OREO were as follows: Years ended December 31, (Dollars in thousands) 2019 2018 2017 Balance at beginning of year $ 1,401 $ 2,781 $ 6,284 Additions Commercial 415 1,269 1,732 Residential 2,033 1,913 2,387 Total additions 2,448 3,182 4,119 Disposals Commercial (541 ) (2,967 ) (5,409 ) Residential (912 ) (830 ) (1,574 ) Total disposals (1,453 ) (3,797 ) (6,983 ) Valuation adjustments Commercial (112 ) (355 ) (439 ) Residential (251 ) (410 ) (200 ) Total valuation adjustments (363 ) (765 ) (639 ) Balance at end of year $ 2,033 $ 1,401 $ 2,781

ALLOWANCE FOR LOAN AND LEASE LO

ALLOWANCE FOR LOAN AND LEASE LOSSES	12 Months Ended
	Dec. 31, 2019
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: 2019 (Dollars in thousands) Commercial & industrial Lease financing Construction real estate Commercial real estate Residential real estate Home equity Installment Credit card Total Allowance for loan and lease losses Balance at beginning of year $ 18,746 $ 1,130 $ 3,413 $ 21,048 $ 4,964 $ 5,348 $ 362 $ 1,531 $ 56,542 Provision for loan and lease losses 23,631 3 (1,100 ) 5,107 739 695 2 1,521 30,598 Gross charge-offs (26,676 ) (162 ) 0 (3,689 ) (677 ) (2,591 ) (223 ) (1,547 ) (35,565 ) Recoveries 2,883 0 68 1,113 273 1,335 251 152 6,075 Total net charge-offs (23,793 ) (162 ) 68 (2,576 ) (404 ) (1,256 ) 28 (1,395 ) (29,490 ) Ending allowance for loan and lease losses $ 18,584 $ 971 $ 2,381 $ 23,579 $ 5,299 $ 4,787 $ 392 $ 1,657 $ 57,650 2018 (Dollars in thousands) Commercial & industrial Lease financing Construction real estate Commercial real estate Residential real estate 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 (Dollars in thousands) Commercial & industrial Lease financing Construction real estate Commercial real estate Residential real estate 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 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, 2019 (Dollars in thousands) Commercial & industrial Lease financing Construction real estate Commercial real estate Residential real estate Home equity Installment Credit card Total Ending allowance on loans individually evaluated for impairment $ 2,044 $ 0 $ 0 $ 113 $ 18 $ 0 $ 0 $ 0 $ 2,175 Ending allowance on loans collectively evaluated for impairment 16,540 971 2,381 23,466 5,281 4,787 392 1,657 55,475 Ending allowance for loan and lease losses $ 18,584 $ 971 $ 2,381 $ 23,579 $ 5,299 $ 4,787 $ 392 $ 1,657 $ 57,650 Loans and Leases Ending balance of loans individually evaluated for impairment $ 27,480 $ 223 $ 0 $ 10,831 $ 15,162 $ 5,700 $ 204 $ 0 $ 59,600 Ending balance of loans collectively evaluated for impairment 2,438,397 88,141 493,182 4,183,820 1,040,787 766,169 82,385 49,184 9,142,065 Total loans $ 2,465,877 $ 88,364 $ 493,182 $ 4,194,651 $ 1,055,949 $ 771,869 $ 82,589 $ 49,184 $ 9,201,665 December 31, 2018 (Dollars in thousands) Commercial & industrial Lease financing Construction real estate Commercial real estate Residential real estate 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

PREMISES AND EQUIPMENT

PREMISES AND EQUIPMENT	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
PREMISES AND EQUIPMENT	Premises and Equipment Premises and equipment at December 31 were as follows: (Dollars in thousands) 2019 2018 Land and land improvements $ 54,958 $ 57,701 Buildings 163,277 161,817 Furniture and fixtures 74,881 66,567 Leasehold improvements 31,728 29,086 Construction in progress 4,096 5,731 328,940 320,902 Less: Accumulated depreciation and amortization 114,434 105,250 Total $ 214,506 $ 215,652 Rental expense recorded under operating leases in 2019 , 2018 and 2017 was $11.2 million , $9.1 million and $7.1 million , respectively.

LEASES

LEASES	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	Leases A lease is defined as a contract, or part of a contract, that conveys the right to control the use of identified property, plant or equipment for a period of time in exchange for consideration. First Financial is primarily the lessee in its leasing agreements, and substantially all of those agreements are for real estate property for branches, ATM locations and office space. On January 1, 2019, the Company adopted Topic 842 and all subsequent modifications. For First Financial, this adoption primarily affected the accounting treatment for operating lease agreements in which the Company is the lessee. Substantially all of the Company's leases are classified as operating leases, and therefore, were previously not recognized on the Company’s Consolidated Balance Sheets. With the adoption of Topic 842, operating lease agreements were required to be recognized on the Consolidated Balance Sheets as an ROU asset and a corresponding lease liability. The Company's right to use an asset over the life of a lease is recorded as a "right of use" asset in Accrued interest and other assets on the Consolidated Balance Sheet and was $58.6 million at December 31, 2019 . Certain adjustments to the ROU asset may be required for items such as initial direct costs paid or incentives received. First Financial recorded a $64.3 million lease liability in Accrued interest and other liabilities on the Consolidated Balance Sheet at December 31, 2019 . The calculated amount of the ROU assets and lease liabilities are impacted by the length of the lease term and the discount rate used to calculate the present value of minimum lease payments. Regarding the discount rate, Topic 842 requires the use of the rate implicit in the lease whenever this rate is readily determinable. As this rate is rarely determinable, the Company utilizes its incremental borrowing rate at lease inception, on a collateralized basis, over a similar term. For operating leases existing prior to January 1, 2019, the rate was based upon the remaining lease term as of that date. Leases with an initial term of 12 months or less are not recorded on the balance sheet and First Financial recognizes lease expense for these leases on a straight-line basis over the term of the lease. Most leases include one or more options to renew, with renewal terms that can extend the lease term from one to 20 years or more. The exercise of renewal options on operating leases is at the Company's sole discretion, and certain leases may include options to purchase the leased property. If at lease inception, the Company considers the exercising of a renewal option to be reasonably certain, the Company will include the extended term in the calculation of the ROU asset and lease liability. First Financial does not enter into lease agreements which contain material residual value guarantees or material restrictive covenants. Certain leases provide for increases in future minimum annual rental payments as defined in the lease agreements and leases generally also include real estate taxes and common area maintenance charges in the annual rental payments. The components of lease expense were as follows: Year ended (dollars in thousands) December 31, 2019 Operating lease cost $ 7,324 Short-term lease cost 55 Variable lease cost 2,553 Total operating lease cost $ 9,932 Future minimum commitments due under these lease agreements as of December 31, 2019 are as follows: (dollars in thousands) Operating leases 2020 $ 7,200 2021 7,166 2022 6,640 2023 6,711 2024 6,457 Thereafter 50,504 Total lease payments 84,678 Less imputed interest 20,401 Total $ 64,277 The lease term and discount rate at December 31, 2019 were as follows: Operating leases Weighted-average remaining lease term 15.6 years Weighted-average discount rate 3.43 % Supplemental cash information at December 31, 2019 related to leases was as follows: Year ended (dollars in thousands) December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 7,335 ROU assets obtained in exchange for lease obligations Operating leases 64,902

GOODWILL AND OTHER INTANGIBLE A

GOODWILL AND OTHER INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2019
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, 2019 , 2018 and 2017 are shown below. (Dollars in thousands) 2019 2018 2017 Balance at beginning of year $ 880,251 $ 204,084 $ 204,084 Goodwill resulting from business combinations 57,520 676,167 0 Balance at end of year $ 937,771 $ 880,251 $ 204,084 During 2019, First Financial recorded $58.0 million of additions to goodwill resulting from the Bannockburn acquisition. During 2018, First Financial recorded additions to goodwill of $676.2 million resulting from the merger with MSFG, and First Financial recorded its final adjustments to goodwill related to the MSFG merger in the first quarter of 2019. For further detail on the merger with MSFG or the acquisition of Bannockburn, see Note 23 - Business Combinations. Goodwill is evaluated for impairment on an annual basis as of October 1 of each year, or whenever events or changes in circumstances indicate that the fair value of a reporting unit may be below its carrying value. First Financial performed its annual impairment test of goodwill as of October 1, 2019 and no impairment was indicated. As of December 31, 2019 , no events or changes in circumstances indicated that the fair value of a reporting unit was below its carrying value. Other intangible assets. Other intangible assets consist primarily of core deposit, customer list and other miscellaneous intangibles. Core deposit intangibles represent the estimated fair value of acquired customer deposit relationships on the date of acquisition and are amortized on an accelerated basis over their estimated useful lives. First Financial's core deposit intangibles have an estimated weighted average remaining life of 8.0 years . First Financial recorded a $39.4 million customer list intangible asset in conjunction with the Bannockburn merger to account for the obligation or advantage on the part of either the Company or the customer to continue the pre-existing relationship subsequent to the merger. The customer list intangible asset is amortized on a straight-line basis over its estimated useful life of 11 years . Other miscellaneous intangibles include purchase commissions, non-compete agreements and trade name intangibles. Other intangible assets are included in Other intangibles in the Consolidated Balance Sheets. The gross carrying amount and accumulated amortization of other intangible assets at December 31, 2019 and December 31, 2018 were as follows: (Dollars in thousands) December 31, 2019 December 31, 2018 Amortized intangible assets Core deposit intangibles $ 51,031 $ (21,149 ) $ 54,357 $ (16,500 ) Customer list 39,420 (1,195 ) 0 0 Other 10,093 (1,999 ) 3,763 (815 ) Total $ 100,544 $ (24,343 ) $ 58,120 $ (17,315 ) Amortization expense recognized on intangible assets for 2019 , 2018 and 2017 was $9.7 million , $7.4 million and $1.3 million , respectively. The estimated amortization expense of intangible assets for the next five years is as follows: (Dollars in thousands) Intangible amortization 2020 $ 11,670 2021 10,263 2022 7,718 2023 6,739 2024 6,670

DEPOSITS

DEPOSITS	12 Months Ended
	Dec. 31, 2019
Deposits [Abstract]
Deposit Liabilities Disclosures [Text Block]	Deposits Time deposits that meet or exceed the FDIC insurance limit of $250,000 at December 31, 2019 and 2018 were $285.0 million and $284.9 million , respectively. Scheduled maturities of all time deposits for the next five years were as follows: (Dollars in thousands) Time deposits 2020 $ 1,752,552 2021 294,579 2022 141,261 2023 37,757 2024 13,272 Thereafter 1,020 Total $ 2,240,441

BORROWINGS

BORROWINGS	12 Months Ended
	Dec. 31, 2019
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 $ 9,755 Collateralized mortgage obligations 80,426 Total $ 90,181 Securities sold under agreements to repurchase are secured by securities with a carrying amount of $90.2 million and $85.5 million , as of December 31, 2019 and 2018 , respectively. First Financial has a $30.0 million short-term credit facility with an unaffiliated bank that matures in September, 2020. 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, 2019 and December 31, 2018 , 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, 2019 and December 31, 2018 . The following is a summary of short-term borrowings for the last three years: 2019 2018 2017 (Dollars in thousands) Amount Rate Amount Rate Amount Rate At December 31, Federal funds purchased and securities sold under agreements to repurchase $ 165,181 0.85 % $ 183,591 1.65 % $ 72,265 0.19 % FHLB borrowings 1,151,000 1.73 % 857,100 2.48 % 742,300 1.43 % Total $ 1,316,181 1.62 % $ 1,040,691 2.33 % $ 814,565 1.32 % Average for the year Federal funds purchased and securities sold under agreements to repurchase $ 155,859 1.15 % $ 87,221 0.58 % $ 69,766 0.19 % FHLB borrowings 990,860 2.37 % 857,028 2.03 % 760,558 1.05 % Other short-term borrowings 0 0.00 % 3,178 4.36 % 41 4.07 % Total $ 1,146,719 1.90 % $ 947,427 1.90 % $ 830,365 0.98 % Maximum month-end balances Federal funds purchased and securities sold under agreements to repurchase $ 260,621 $ 183,591 $ 130,633 FHLB borrowings 1,171,400 1,170,800 957,700 Other short-term borrowings 0 10,000 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 included $242.4 million and $400.6 million of fixed rate FHLB long-term advances as of December 31, 2019 and December 31, 2018 , respectively. As of December 31, 2019 , long-term FHLB advances had a weighted average interest rate of 1.94% . 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, 2019 , had collateral pledged with a book value of $6.2 billion . The following is a summary of First Financial's long-term debt: 2019 2018 (Dollars in thousands) Amount Average Rate Amount Average Rate FHLB borrowings $ 242,428 1.94 % $ 400,599 2.08 % Subordinated debt 170,967 4.97 % 170,550 5.28 % Unamortized debt issuance costs (1,007 ) n/a (1,185 ) n/a Capital lease liability 1,213 4.48 % 0 0.00 % Capital loan with municipality 775 0.00 % 775 0.00 % Total long-term debt $ 414,376 3.20 % $ 570,739 3.04 % As of December 31, 2019 , First Financial's long-term debt matures as follows: (Dollars in thousands) Long-term debt 2020 $ 104,059 2021 19,052 2022 49,451 2023 49 2024 51 Thereafter 241,714 Total $ 414,376

DERIVATIVES

DERIVATIVES	12 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVES	Derivatives First Financial uses certain derivative instruments, including rate caps, floors, swaps and foreign exchange contracts, to meet the operating needs of its clients while managing the interest and currency rate risk associated with certain transactions. First Financial may also utilize interest rate swaps to manage the interest rate risk profile of the Company. Interest rate payments are exchanged with counterparties, based on the notional amount 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 does not use derivatives for speculative purposes. First Financial manages this market value credit risk through counterparty credit policies including a review of total derivative notional position to total assets, total credit exposure to total capital and counterparty credit exposure risk. For discussion of First Financial's accounting for derivative instruments, see Note 1 – Summary of Significant Accounting Policies. 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. At December 31, 2019 , for interest rate derivatives, the Company had a total counterparty notional amount outstanding of $1.9 billion , spread among eighteen counterparties, with an outstanding liability from these contracts of $67.5 million . At December 31, 2018 , the Company had interest rate derivatives with 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 . 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 associated with problem loans through the Company's ALLL committee. First Financial considers the market value of a derivative instrument to be part of the carrying value of the related loan for these purposes as the borrower is contractually obligated to pay First Financial this amount in the event the derivative contract is terminated. In connection with its use of derivative instruments, First Financial and its counterparties may be required to post cash collateral to offset the market position of the derivative instruments. First Financial maintains the right to offset these derivative positions with the collateral posted against them by or with the relevant counterparties. Foreign Exchange Contracts. First Financial may enter into foreign exchange derivative contracts for the benefit of commercial customers to hedge their exposure to foreign currency fluctuations. Similar to the hedging of interest rate risk from interest rate derivative contracts, First Financial also enters into foreign exchange contracts with major financial institutions to economically hedge a substantial portion of the exposure from client driven foreign exchange activity. These derivatives are classified as free-standing instruments with the revaluation gain or loss recorded in Foreign exchange income in the Consolidated Statements of Income. The Company has risk limits and internal controls in place to help ensure that it is not taking excessive risk when providing this service to customers. These controls include an independent determination of currency volatility and credit equivalent exposure on these contracts, counterparty credit approvals and country limits performed by independent risk management. At December 31, 2019 , the Company had total counterparty notional amount outstanding of $1.9 billion spread among six counterparties, with an estimated fair value of $18.3 million at December 31, 2019 related to foreign exchange contracts, which is included in Accrued interest and other liabilities in the Consolidated Balance Sheets. In connection with its use of foreign exchange contracts, First Financial and its counterparties may be required to post cash collateral to offset the market position of the derivative instruments. First Financial maintains the right to offset these derivative positions with the collateral posted against them by or with the relevant counterparties. The following table details the location and amounts recognized in the Consolidated Balance Sheets for client derivatives: December 31, 2019 December 31, 2018 Estimated fair value Estimated fair value (Dollars in thousands) Balance Sheet Classification Notional amount Gain Loss Notional amount Gain Loss Client derivatives-instruments associated with loans Matched interest rate swaps with borrower Accrued interest and other assets and other liabilities $ 1,923,375 $ 70,799 $ (2,636 ) $ 1,359,990 $ 17,402 $ (11,787 ) Matched interest rate swaps with counterparty Accrued interest and other liabilities 1,923,375 2,636 (70,808 ) 1,359,990 11,787 (17,401 ) Foreign exchange contracts Matched foreign exchange contracts with customers Accrued interest and other assets 1,869,934 28,739 (10,433 ) 0 0 0 Match foreign exchange contracts with counterparty Accrued interest and other liabilities 1,869,934 10,433 (28,739 ) 0 0 0 Total $ 7,586,618 $ 112,607 $ (112,616 ) $ 2,719,980 $ 29,189 $ (29,188 ) The following table discloses the gross and net amounts of client derivative liabilities recognized in the Consolidated Balance Sheets: December 31, 2019 December 31, 2018 (Dollars in thousands) Gross amounts of recognized liabilities Gross amounts offset in the Consolidated Balance Sheets Net amounts of (assets)/liabilities presented in the Consolidated Balance Sheets Gross amounts of recognized liabilities Gross amounts offset in the Consolidated Balance Sheets Net amounts of (assets)/liabilities presented in the Consolidated Balance Sheets Client derivatives Matched interest rate swaps $ 73,444 $ (147,193 ) $ (73,749 ) $ 29,189 $ (14,577 ) $ 14,612 Foreign exchange contracts with counterparty 39,172 (41,202 ) (2,030 ) 0 0 0 Total $ 112,616 $ (188,395 ) $ (75,779 ) $ 29,189 $ (14,577 ) $ 14,612 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, 2019 : (Dollars in thousands) Notional amount Average maturity (years) Fair value Client derivatives-interest rate contracts Receive fixed, matched interest rate swaps with borrower $ 1,923,375 6.0 $ 68,163 Pay fixed, matched interest rate swaps with counterparty 1,923,375 6.0 (68,172 ) Client derivatives-foreign exchange contracts Foreign exchange contracts - pay USD 1,869,934 0.6 18,306 Foreign exchange contracts - receive USD 1,869,934 0.6 (18,306 ) Total client derivatives $ 7,586,618 3.3 $ (9 ) 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 $216.2 million as of December 31, 2019 and $138.4 million as of December 31, 2018 . The fair value of these agreements were recorded in Accrued interest and other liabilities on the Consolidated Balance Sheets was $0.2 million at December 31, 2019 and $0.1 million at December 31, 2018. 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 loans are 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, 2019 , the notional amount of the IRLCs was $33.4 million and the notional amount of forward commitments was $37.8 million . As of December 31, 2018 , the notional amount of IRLCs was $20.8 million and the notional amount of forward commitments was $12.3 million . The fair value of these agreements was $0.9 million at December 31, 2019 and was insignificant at December 31, 2018 and was recorded in Accrued interest and other assets on the Consolidated Balance Sheets.

RELATED PARTIES TRANSACTIONS

RELATED PARTIES TRANSACTIONS	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Loans to Related Parties	Related Party Transactions Outstanding balance of loans to directors, executive officers, principal holders of First Financial’s common stock and certain related persons were as follows: (Dollars in thousands) 2019 Beginning balance $ 2,732 Additions 4,348 Deductions (1,791 ) Ending balance $ 5,289 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
	Dec. 31, 2019
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 $0.6 million and $0.7 million of reserves for unfunded commitments recorded in Accrued interest and other liabilities on the Consolidated Balance Sheets as of December 31, 2019 and 2018 , 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 $3.3 billion and $3.0 billion at December 31, 2019 and 2018 , respectively. As of December 31, 2019 , loan commitments with a fixed interest rate totaled $123.7 million while commitments with variable interest rates totaled $3.2 billion . At 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, 2019 and 2018 and have maturities ranging from less than 1 year to 31.6 years for December 31, 2019 and between 1 and 30 years for December 31, 2018 . 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 $33.4 million and $32.7 million at December 31, 2019 , and 2018 , 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 $38.5 million and $39.4 million as of December 31, 2019 and 2018 , respectively. The Company recognized tax credits of $6.2 million , $4.9 million and $3.2 million related to its investments in affordable housing projects for the years ended December 31, 2019 , 2018 and 2017 , respectively. The Company recognized amortization expense which was included in income tax expense of $6.9 million , $5.7 million and $4.2 million for the years ended December 31, 2019 , 2018 and 2017 , respectively. First Financial had no affordable housing contingent commitments as of December 31, 2019 or December 31, 2018 . 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 $3.1 million at December 31, 2019 , and $3.9 million at December 31, 2018 . The maximum exposure to loss related to these investments was $5.1 million at December 31, 2019 and $3.9 million at December 31, 2018 , representing the Company’s investment balance and its unfunded commitments to invest additional amounts. Investments in historic tax credits resulted in $3.5 million , $0.5 million and $13.7 million of tax credits for the years ended December 31, 2019 , 2018 and 2017 , respectively. 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, 2019 . 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, 2019 or December 31, 2018 .

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
INCOME TAXES	Income Taxes Income tax expense consisted of the following components: (Dollars in thousands) 2019 2018 2017 Current expense Federal $ 31,343 $ 34,330 $ 22,599 State 854 1,029 1,265 Total current expense 32,197 35,359 23,864 Deferred expense (benefit) Federal 10,946 4,675 (4,657 ) State 1,644 1,592 169 Total deferred expense (benefit) 12,590 6,267 (4,488 ) Income tax expense $ 44,787 $ 41,626 $ 19,376 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) 2019 2018 2017 Income taxes computed at federal statutory rate on income before income taxes (21% in 2019 and 2018; 35% in 2017) $ 51,001 $ 44,986 $ 40,657 Benefit from tax-exempt income (5,964 ) (4,499 ) (3,427 ) Tax credits (10,075 ) (5,439 ) (16,806 ) Tax rate reduction impact 0 0 (8,191 ) Basis reduction on tax credit 738 0 4,599 Tax benefit of equity compensation (140 ) (565 ) (1,449 ) State income taxes, net of federal tax benefit 1,973 2,070 932 Affordable housing investments 5,825 4,725 2,798 Other 1,429 348 263 Income tax expense $ 44,787 $ 41,626 $ 19,376 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, which resulted in an $8.2 million reduction in tax expense in 2017. The major components of the temporary differences that gave rise to deferred tax assets and liabilities at December 31, 2019 , and 2018 , were as follows: (Dollars in thousands) 2019 2018 Deferred tax assets Allowance for loan and lease losses $ 13,011 $ 12,782 Fair value adjustments on business combinations 6,470 11,199 Deferred compensation 228 392 Postretirement benefits other than pension liability 666 676 Accrued stock-based compensation 1,296 1,145 OREO write-downs 162 118 Interest on nonaccrual loans 548 1,160 Accrued expenses 4,708 5,808 Net unrealized losses on investment securities and derivatives 0 3,221 State net operating loss 2,792 3,119 Leasing liability 14,806 0 Federal tax credit carryforwards 0 873 Other 816 425 Total deferred tax assets 45,503 40,918 Deferred tax liabilities Tax depreciation in excess of book depreciation (10,970 ) (9,530 ) FHLB and FRB stock (4,043 ) (4,044 ) Mortgage-servicing rights (2,435 ) (2,285 ) Leasing activities (7,349 ) (3,881 ) Retirement obligation (8,511 ) (6,614 ) Intangible assets (11,647 ) (12,310 ) Deferred loan fees and costs (1,100 ) (131 ) Prepaid expenses (623 ) (582 ) Limited partnership investments (2,249 ) (2,367 ) Net unrealized gains on investment securities (11,359 ) 0 Foreign exchange deferred income (2,845 ) 0 Right of use assets (13,354 ) 0 Other (2,048 ) (1,867 ) Total deferred tax liabilities (78,533 ) (43,611 ) Total net deferred tax liability $ (33,030 ) $ (2,693 ) In conjunction with the MSFG merger, First Financial acquired a state net operating loss. At December 31, 2019 and 2018, the state net operating loss carryforward was $3.6 million and $3.9 million , and begin to expire in 2024 and 2022, respectively. The Company expects to fully utilize this net operating loss and, therefore, a valuation allowance is not required at December 31, 2019 and 2018. The acquired MSFG state net operating loss is subject to IRC Section 382 and is 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 and the reversal of deferred tax liabilities during the same period. 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, 2019 and 2018 . The Bank’s retained earnings at December 31, 2019 and December 31, 2018 included base-year bad debt reserves of $16.1 million as a result of the merger with MSFG. 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 been recorded. At both December 31, 2019 and 2018 , First Financial had $2.4 million and $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 gross unrecognized tax benefits as of December 31, 2019 and 2018 is as follows: (Dollars in thousands) 2019 2018 Balance at beginning of year $ 3,735 $ 3,735 Settlements (729 ) 0 Balance at end of year $ 3,006 $ 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, 2019 and 2018, 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 2016 have been closed and are no longer subject to U.S. federal income tax examinations. Tax years 2016 through 2019 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 2019 remain open to state and local examination by various other jurisdictions.

EMPLOYEE BENEFIT PLANS

EMPLOYEE BENEFIT PLANS	12 Months Ended
	Dec. 31, 2019
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. First Financial recorded expense related to its pension plan of $1.0 million for 2019 and $0.9 million for 2018 . During 2017 , First Financial recorded income of $0.6 million . The components of net periodic benefit cost other than the service cost component are included in Other noninterest expense while service costs are recorded as a component Salaries and employee benefits in the Consolidated Statements of Income. First Financial made no cash contributions to the pension plan in 2019 , 2018 or 2017 and does not expect to make any contributions in 2020. 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) 2019 2018 Change in benefit obligation Benefit obligation at beginning of year $ 68,286 $ 71,154 Service cost 6,591 6,501 Interest cost 2,778 2,394 Actuarial (gain) loss 6,848 (4,032 ) Benefits paid, excluding settlement (9,459 ) (7,731 ) Benefit obligation at end of year 75,044 68,286 Change in plan assets Fair value of plan assets at beginning of year 130,078 144,349 Actual return on plan assets 21,197 (6,540 ) Benefits paid, excluding settlement (9,459 ) (7,731 ) Fair value of plan assets at end of year 141,816 130,078 Amounts recognized in the Consolidated Balance Sheets Assets 66,772 61,792 Liabilities 0 0 Net amount recognized $ 66,772 $ 61,792 Amounts recognized in accumulated other comprehensive income (loss) Net actuarial loss $ 37,278 $ 43,711 Net prior service cost (1,095 ) (1,508 ) Deferred tax assets (8,242 ) (9,613 ) Net amount recognized $ 27,941 $ 32,590 Change in accumulated other comprehensive income (loss) $ (4,649 ) $ 12,959 Accumulated benefit obligation $ 74,424 $ 66,320 The components of net periodic benefit cost are shown in the table that follows: December 31, (Dollars in thousands) 2019 2018 2017 Service cost $ 6,591 $ 6,501 $ 4,894 Interest cost 2,778 2,394 2,325 Expected return on assets (9,718 ) (9,811 ) (9,358 ) Amortization of prior service cost (413 ) (413 ) (413 ) Recognized net actuarial loss 1,803 2,188 1,924 Net periodic benefit (income) cost 1,041 859 (628 ) Other changes recognized in accumulated other comprehensive income (loss) Net actuarial (gain) loss (4,630 ) 12,319 (2,775 ) Prior service cost 0 0 0 Amortization of prior service cost 413 413 413 Amortization of gain (1,803 ) (2,188 ) (1,924 ) Total recognized in accumulated other comprehensive income (loss) (6,020 ) 10,544 (4,286 ) Total recognized in net periodic benefit cost and accumulated other comprehensive income (loss) $ (4,979 ) $ 11,403 $ (4,914 ) Amount expected to be recognized in net periodic pension expense in the coming year Amortization of (gain) loss $ 2,079 $ 1,867 $ 2,090 Amortization of prior service credit (413 ) (413 ) (413 ) The pension plan assumptions are shown in the table that follows: December 31, 2019 2018 2017 Benefit obligations Discount rate 3.33 % 4.31 % 3.43 % Rate of compensation increase 3.50 % 3.50 % 3.50 % Net periodic benefit cost Discount rate 4.31 % 3.43 % 3.88 % Expected return on plan assets 7.25 % 7.25 % 7.25 % Rate of compensation increase 3.50 % 3.50 % 3.50 % The fair value of the plan assets as of December 31, 2019 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 $ 195 $ 195 $ 0 $ 0 U. S. Government agencies 5,357 0 5,357 0 Fixed income mutual funds 75,720 75,720 0 0 Equity mutual funds 60,544 60,544 0 0 Total $ 141,816 $ 136,459 $ 5,357 $ 0 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 level within the fair value hierarchy is based on the lowest level of input that is significant in the fair value measurement. See Note 22 – 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) Expected benefit payments 2020 $ 5,611 2021 5,210 2022 5,173 2023 5,125 2024 6,070 Thereafter 35,362 401(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. The Company made no contributions to the 401(k) plan during the years ended December 31, 2019 and 2018. First Financial recorded $1.9 million of expense related to the Company's contributions to the 401(k) plan during 2017

REVENUE RECOGNITION REVENUE REC

REVENUE RECOGNITION REVENUE RECOGNITION (Notes)	12 Months Ended
	Dec. 31, 2019
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, derivatives and foreign exchange, that are outside the scope of ASU No. 2014-09, Revenue from Contracts with Customers. The Company's services that fall within the scope of ASU 2019-09 are presented within Noninterest income and are recognized as revenue when 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. 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 2019 was $30.4 million , and was partially offset by $11.9 million of expenses within Noninterest income. Gross interchange income for 2018 was $31.3 million , and was partially offset by $11.0 million of expenses within Noninterest income. Other. Other noninterest income consists of other recurring revenue streams such as transaction fees, safe deposit rental income, insurance commissions, merchant referral income, gain (loss) on sale of OREO 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 fees 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. 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. 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
	Dec. 31, 2019
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, 2019 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 $ 65,858 $ (370 ) $ 66,228 $ (14,269 ) $ 51,959 $ (11,601 ) $ 51,959 $ 906 $ 41,264 Unrealized gain (loss) on derivatives 281 0 281 (64 ) 217 (217 ) 217 0 0 Retirement obligation 4,630 (1,390 ) 6,020 (1,371 ) 4,649 (32,590 ) 4,649 0 (27,941 ) Total $ 70,769 $ (1,760 ) $ 72,529 $ (15,704 ) $ 56,825 $ (44,408 ) $ 56,825 $ 906 $ 13,323 December 31, 2018 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 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 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 $ 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 ) 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) 2019 2018 2017 Affected Line Item in the Consolidated Statements of Income Realized gains and losses on securities available-for-sale $ (370 ) $ (161 ) $ 1,649 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) (1,803 ) (2,188 ) (1,924 ) Other noninterest expense Amortization and settlement charges of defined benefit pension items (1,390 ) (1,775 ) (1,511 ) Total reclassifications for the period, before tax $ (1,760 ) $ (1,936 ) $ 138 (1) Negative amounts are debits to profit/loss. (2) Included in the computation of net periodic pension cost (see Note 16 - Employee Benefit Plans for additional details).

CAPITAL

CAPITAL	12 Months Ended
	Dec. 31, 2019
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 7.00% at December 31, 2019 and 6.38% at December 31, 2018 and a phased-in capital conservation buffer of 2.5% of risk-weighted assets that began on January 1, 2016 at 0.625% until it was fully phased in as of January 1, 2019. Further, the minimum ratio of tier 1 capital to risk-weighted assets increased to 8.5% at December 31, 2019 and all banks are subject to a 4.0% minimum leverage ratio. The required Total risk-based capital ratio is 10.50% . 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, 2019 , management believes that First Financial met all capital adequacy requirements to which it was subject. To be categorized as well-capitalized, First Financial must maintain minimum Total risk-based capital, Tier 1 risk-based capital and Tier 1 leverage ratios as set forth in the table that follows. The Company's most recent regulatory notifications categorized First Financial as "well-capitalized" under the regulatory framework for prompt corrective action. There have been no conditions or events since those notifications that management believes have changed the Company's categorization. Total regulatory capital exceeded the “minimum” requirement by $318.3 million on a consolidated basis at December 31, 2019 . The following tables present the actual and required capital amounts and ratios as of December 31, 2019 and 2018 under the Basel III Capital Rules. The minimum required capital amounts presented include the minimum required capital levels based on the phase-in provisions of the Basel III Capital Rules as of the year presented. The 2018 table includes the minimum required capital levels as of January 1, 2019 when the Basel III Capital Rules had 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. Actual Minimum capital PCA requirement to be (Dollars in thousands) Capital Ratio Capital Ratio Capital Ratio December 31, 2019 Common equity tier 1 capital to risk-weighted assets Consolidated $ 1,245,746 11.30 % $ 771,666 7.00 % N/A N/A First Financial Bank 1,333,978 12.11 % 770,997 7.00 % $ 715,926 6.50 % Tier 1 capital to risk-weighted assets Consolidated 1,288,185 11.69 % 937,023 8.50 % N/A N/A First Financial Bank 1,334,082 12.11 % 936,211 8.50 % $ 881,140 8.00 % Total capital to risk-weighted assets Consolidated 1,475,813 13.39 % 1,157,498 10.50 % N/A N/A First Financial Bank 1,399,817 12.71 % 1,156,496 10.50 % 1,101,425 10.00 % Leverage Consolidated 1,288,185 9.58 % 537,606 4.00 % N/A N/A First Financial Bank 1,334,082 9.93 % 537,299 4.00 % 671,623 5.00 % Actual Minimum capital PCA requirement 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 6.38 % N/A N/A $ 716,881 7.00 % First Financial Bank 1,279,492 12.50 % 652,590 6.38 % $ 665,386 6.50 % 716,570 7.00 % Tier 1 capital to risk-weighted assets Consolidated 1,257,366 12.28 % 806,491 7.88 % N/A N/A 870,499 8.50 % First Financial Bank 1,279,596 12.50 % 806,141 7.88 % 818,937 8.00 % 870,120 8.50 % Total capital to risk-weighted assets Consolidated 1,444,146 14.10 % 1,011,314 9.88 % N/A N/A 1,075,322 10.50 % First Financial Bank 1,344,388 13.13 % 1,010,875 9.88 % 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 % Share repurchases. In January 2019, First Financial's board of directors approved a stock repurchase plan, replacing the plan approved in 2012. The 2019 plan authorizes the purchase of up to 5,000,000 shares of the Company's common stock. First Financial repurchased 2,753,272 shares at an average market price of $24.05 under this plan during 2019. At December 31, 2019 , 2,246,728 common shares remained available for repurchase under the 2019 plan. There were no share repurchases in 2018 or 2017. 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
	Dec. 31, 2019
Share-based Payment Arrangement [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 (within salaries and employee benefits on the Consolidated Statements of Income) of $8.0 million , $6.2 million and $5.4 million for the years ended December 31, 2019, 2018 and 2017, respectively, related to stock options and restricted stock awards. Total unrecognized compensation cost related to non-vested share-based compensation was $8.5 million at December 31, 2019 and is expected to be recognized over a weighted average period of 1.93 years . As of December 31, 2019 , First Financial had a single active stock-based compensation plan, the Amended and Restated 2012 Stock Plan, under which additional awards may be granted. At December 31, 2019 , there were 1,513,826 shares available for issuance under the Amended and Restated 2012 Stock Plan. In April 2018, in conjunction with the MSFG merger, First Financial assumed existing MSFG stock 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, 2019, 37,856 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 new options were granted in 2019 , 2018 or 2017 . Stock option activity for the year ended December 31, 2019 , 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 62,410 $ 9.08 Granted 0 0.00 Exercised (24,554 ) 8.37 Forfeited or expired 0 0.00 Outstanding at end of year 37,856 $ 9.54 3.12 $ 602 Exercisable at end of year 37,856 $ 9.54 3.12 $ 602 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. 2019 2018 2017 Total intrinsic value of options exercised $ 462 $ 734 $ 1,533 Cash received from exercises $ 90 $ 284 $ 341 Tax benefit from exercises $ 1,844 $ 1,439 $ 1,991 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: 2019 2018 2017 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 462,446 $ 26.39 468,372 $ 21.63 648,817 $ 17.82 Granted 395,023 26.55 303,930 28.94 234,529 27.36 Vested (295,633 ) 24.94 (267,031 ) 20.94 (307,825 ) 18.12 Forfeited (31,267 ) 28.63 (42,825 ) 26.38 (107,149 ) 21.18 Nonvested at end of year 530,569 $ 27.19 462,446 $ 26.39 468,372 $ 21.63 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 2019 , 2018 and 2017 was $7.4 million , $5.6 million and $5.6 million , respectively.

EARNINGS PER COMMON SHARE

EARNINGS PER COMMON SHARE	12 Months Ended
	Dec. 31, 2019
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) 2019 2018 2017 Numerator Net income $ 198,075 $ 172,595 $ 96,787 Denominator Basic earnings per common share - weighted average shares 98,305,570 88,582,090 61,529,460 Effect of dilutive securities Employee stock awards 545,901 514,680 581,329 Warrants 0 517,435 60,801 Diluted earnings per common share - adjusted weighted average shares 98,851,471 89,614,205 62,171,590 Earnings per share available to common shareholders Basic $ 2.01 $ 1.95 $ 1.57 Diluted $ 2.00 $ 1.93 $ 1.56 First Financial had no warrants outstanding to purchase the Company's common stock as of December 31, 2019 . Warrants acquired in the MSFG merger were outstanding as of December 31, 2018 and represented the right to purchase 804,858 shares of First Financial's common stock at an exercise price of $10.62 per share. These warrants were exercised in January 2019. At December 31, 2017, First Financial had warrants outstanding representing the right to purchase 104,200 shares of common stock at an exercise price of $12.12 . These warrants expired in December 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, 2019 , 2018 , or 2017 . As of December 31, 2019 , 2018 , and 2017 , First Financial was authorized to issue 10,000,000 preferred shares, however no

FAIR VALUE DISCLOSURES

FAIR VALUE DISCLOSURES	12 Months Ended
	Dec. 31, 2019
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, 2019 Financial assets Cash and short-term investments $ 257,639 $ 257,639 $ 257,639 $ 0 $ 0 Investment securities held-to-maturity 142,862 142,821 0 142,821 0 Other investments 125,020 N/A N/A N/A N/A Loans held for sale 13,680 13,680 0 13,680 0 Loans and leases 9,144,015 9,134,215 0 0 9,134,215 Accrued interest receivable 39,591 39,591 0 12,743 26,848 Financial liabilities Deposits 10,210,229 10,209,790 0 10,209,790 0 Short-term borrowings 1,316,181 1,316,181 1,316,181 0 0 Long-term debt 414,376 414,937 0 414,937 0 Accrued interest payable 13,671 13,671 1,899 11,772 0 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 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 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 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, 2019 and 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. 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 and foreign exchange contracts at the reporting date, using primarily observable market inputs such as interest rate yield curves and currency exchange rates, 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. 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. 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, 2019 Assets Investment securities available-for-sale $ 100 $ 2,842,794 $ 9,190 $ 2,852,084 Interest rate derivative contracts 0 73,558 0 73,558 Foreign exchange derivative contracts 0 39,172 0 39,172 Total $ 100 $ 2,955,524 $ 9,190 $ 2,964,814 Liabilities Interest rate derivative contracts $ 0 $ 73,750 $ 0 $ 73,750 Foreign exchange derivative contracts 0 39,172 0 39,172 Total $ 0 $ 112,922 $ 0 $ 112,922 Fair Value Measurements Using Assets/Liabilities (Dollars in thousands) Level 1 Level 2 Level 3 at Fair Value December 31, 2018 Assets Investment securities available-for-sale $ 97 $ 2,764,443 $ 14,715 $ 2,779,255 Derivatives 0 29,543 0 29,543 Total $ 97 $ 2,793,986 $ 14,715 $ 2,808,798 Liabilities Derivatives $ 0 $ 29,336 $ 0 $ 29,336 The following table presents a reconciliation for certain AFS securities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the year ended December 31, 2019 . Year ended (dollars in thousands) December 31, 2019 Beginning balance $ 14,715 Accretion (amortization) (552 ) Increase (decrease) in fair value 30 Settlements (5,003 ) Ending balance $ 9,190 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, 2019 Assets Impaired loans $ 0 $ 0 $ 9,268 OREO 0 0 1,088 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

BUSINESS COMBINATIONS

BUSINESS COMBINATIONS	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
BUSINESS COMBINATIONS	Business Combination In August, 2019, the Company completed its acquisition of Bannockburn Global Forex, LLC. Pursuant to the acquisition agreement, First Financial agreed to acquire all of the issued and outstanding membership interests of BGF for aggregate consideration of approximately $114.6 million consisting of $53.7 million in cash and $60.9 million of First Financial common stock. BGF was a privately held capital markets trading firm specializing in foreign currency advisory, hedge analytics and transaction processing for closely held enterprises. Upon completion of the transaction, Bannockburn became a division of the Bank, but continues to operate as Bannockburn Global Forex, taking advantage of its existing brand recognition within the foreign exchange industry. The Bannockburn 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 were $74.9 million and $18.4 million , respectively, and 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 became available. The measurement period ends in August 2020. Goodwill arising from the BGF acquisition was $58.0 million and reflects the business’s high growth potential and the expectation that the acquisition will provide additional revenue growth and diversification. The goodwill is deductible for income tax purposes as the transaction is considered a taxable exchange. For further detail, see Note 9 – Goodwill and Other Intangible Assets. In April 2018, First Financial completed its acquisition of MainSource Financial Group, Inc. and its banking subsidiary, MainSource Bank. 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 $675.6 million . The goodwill arising from the acquisition largely reflected synergies and cost savings resulting from combining the operations of the companies. First Financial incurred merger related expenses related to the MSFG acquisition of $3.2 million and $37.8 million during the years ended December 31, 2019 and 2018, respectively. The MSFG acquisition provided 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 9 – 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 were subject to refinement for up to one year after the closing date of the acquisition as additional information relative to closing date fair values became available. The fair values of assets acquired and liabilities assumed were considered final as of March 31, 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 for the MSFG merger. 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 71,806 Investment securities available-for-sale 900,935 Investment securities held-to-maturity 171,423 Other investments 28,763 Loans 2,792,572 Premises and equipment 98,814 Intangible assets 42,887 Other assets 167,829 Assets held for sale 127,775 Total assets acquired 4,402,804 Liabilities assumed Deposits 3,263,920 Subordinated notes 49,027 FHLB advances 291,887 Other borrowings 205,620 Other liabilities 32,649 Liabilities held for sale 175,840 Total liabilities assumed 4,018,943 Net identifiable assets 383,861 Goodwill $ 675,643 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 , respectively. The following table presents supplemental pro forma information as if the MSFG 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, 2019
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) 2019 2018 Assets Cash $ 55,869 $ 86,878 Investment securities 1,116 694 Subordinated notes from subsidiaries 7,500 7,500 Investment in subsidiaries Commercial bank 2,272,991 2,078,655 Non-banks 8,260 7,194 Total investment in subsidiaries 2,281,251 2,085,849 Premises and equipment 1,344 1,361 Other assets 77,572 71,817 Total assets $ 2,424,652 $ 2,254,099 Liabilities Subordinated notes $ 171,983 $ 171,416 Dividends payable 849 465 Other liabilities 4,115 3,969 Total liabilities 176,947 175,850 Shareholders’ equity 2,247,705 2,078,249 Total liabilities and shareholders’ equity $ 2,424,652 $ 2,254,099 Statements of Income and Comprehensive Income Years Ended December 31, (Dollars in thousands) 2019 2018 2017 Income Interest income $ 30 $ 23 $ 6 Noninterest income 191 0 86 Dividends from subsidiaries 196,800 107,340 54,600 Total income 197,021 107,363 54,692 Expenses Interest expense 9,552 8,798 6,152 Salaries and employee benefits 8,169 6,413 5,519 Professional services 1,040 5,130 970 Other 6,599 5,648 4,819 Total expenses 25,360 25,989 17,460 Income before income taxes and equity in undistributed net earnings of subsidiaries 171,661 81,374 37,232 Income tax expense (benefit) (5,975 ) (6,687 ) (7,080 ) Equity in undistributed earnings (loss) of subsidiaries 20,439 84,534 52,475 Net income $ 198,075 $ 172,595 $ 96,787 Comprehensive income $ 254,900 $ 153,670 $ 104,840 Statements of Cash Flows Years Ended December 31, (Dollars in thousands) 2019 2018 2017 Operating activities Net income $ 198,075 $ 172,595 $ 96,787 Adjustments to reconcile net income to net cash provided by operating activities Equity in undistributed (earnings) loss of subsidiaries (20,439 ) (84,534 ) (52,475 ) Depreciation and amortization 584 194 193 Stock-based compensation expense 7,969 6,219 5,446 Deferred income taxes 1,255 739 (360 ) (Decrease) increase in dividends payable 384 (10,500 ) 579 Increase (decrease) in other liabilities (244 ) 9,979 (889 ) Decrease (increase) in other assets (7,187 ) 16,346 (6,951 ) Net cash provided by (used in) operating activities 180,397 111,038 42,330 Investing activities Capital contributions to subsidiaries 0 (3,000 ) 0 Net cash acquired (paid) in business combinations (53,660 ) 11,353 0 Proceeds from sales and maturities of investment securities 264 0 0 Purchases of investment securities (500 ) 0 0 Net cash (used in) provided by investing activities (53,896 ) 8,353 0 Financing activities (Decrease) increase in short-term borrowings 0 (8,333 ) 0 Cash dividends paid on common stock (89,097 ) (79,655 ) (41,178 ) Purchases of common stock (66,218 ) 0 0 Proceeds from exercise of stock options, net of shares purchased 90 284 341 Other (2,285 ) (2,528 ) (3,059 ) Net cash (used in) provided by financing activities (157,510 ) (90,232 ) (43,896 ) Net increase (decrease) in cash (31,009 ) 29,159 (1,566 ) Cash at beginning of year 86,878 57,719 59,285 Cash at end of year $ 55,869 $ 86,878 $ 57,719

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2019
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 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 also 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 and FHLB stock, which are both carried at cost, in addition to equity securities which are carried at fair value. Changes in the fair value of equity securities are recorded in Other noninterest income in the Consolidated Statements of Income.
Financing Receivable, Held-for-sale [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 held for sale 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). 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. Management evaluates Commercial loan and lease relationships greater than $250,000 that are considered impaired, or designated as a TDR to determine the need for a specific allowance. This evaluation is 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 delinquent and nonaccrual loans, prevailing economic conditions and changes in lending strategies, among other influencing factors. Consumer loans generally exhibit homogeneous characteristics and are evaluated by loan type. 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. An allowance for loan losses will be established for any subsequent credit deterioration or adverse changes in expected cash flows.
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 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.
Loan Commitments, Policy	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.
Off-Balance-Sheet Credit Exposure, Policy	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.
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, Goodwill, 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 other intangible assets deemed to have indefinite lives 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. 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, 2019 and no impairment was indicated. As of December 31, 2019 , no events or changes in circumstances indicated that the fair value of a reporting unit was below its carrying value.
Other intangible assets, Policy	Other intangible assets. Other intangible assets consist primarily of core deposit, customer list and other miscellaneous 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. First Financial recorded a customer list intangible asset in conjunction with the Bannockburn merger to account for the obligation or advantage on the part of either the Company or the customer to continue the pre-existing relationship subsequent to the merger. The customer list intangible asset is amortized on a straight-line basis over its estimated useful life.
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.
Investments in Historic Tax Credits [Policy Text Block]	Investments in historic tax credits.
Income Tax, Policy	Income taxes.
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 matched 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. First Financial may enter into foreign exchange derivative contracts for the benefit of commercial customers to hedge their exposure to foreign currency fluctuations. Similar to the hedging of interest rate risk from interest rate derivative contracts, First Financial also enters into foreign exchange contracts with major financial institutions to economically hedge a substantial portion of the exposure from client driven foreign exchange activity. These derivatives are classified as free-standing instruments with the revaluation gain or loss recorded in Foreign exchange income in the Consolidated Statements of Income. 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 balances that are on deposit at other depository institutions.
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.
Troubled Debt Restructuring [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.
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, 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. 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 and foreign exchange contracts at the reporting date, using primarily observable market inputs such as interest rate yield curves and currency exchange rates, 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. 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.
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 loans are 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 including a review of total derivative notional position to total assets, total credit exposure to total capital and counterparty credit exposure risk
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
	Dec. 31, 2019
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, 2019 : 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 $ 1 $ 0 $ 100 Securities of U.S. government agencies and corporations 0 0 0 0 156 2 0 158 Mortgage-backed securities - residential 20,818 122 (174 ) 20,766 421,945 9,709 (99 ) 431,555 Mortgage-backed securities - commercial 101,267 571 (1,225 ) 100,613 474,174 4,988 (2,644 ) 476,518 Collateralized mortgage obligations 9,763 0 (108 ) 9,655 769,076 16,753 (385 ) 785,444 Obligations of state and other political subdivisions 11,014 804 (31 ) 11,787 652,986 23,729 (462 ) 676,253 Asset-backed securities 0 0 0 0 400,081 1,414 (1,064 ) 400,431 Other securities 0 0 0 0 79,781 1,959 (115 ) 81,625 Total $ 142,862 $ 1,497 $ (1,538 ) $ 142,821 $ 2,798,298 $ 58,555 $ (4,769 ) $ 2,852,084 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 Unrecognized Unrecognized Fair Amortized Unrealized Unrealized Fair 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
Summary of Investment Securities by Estimated Maturity	The following table provides a summary of investment securities by contractual maturity as of December 31, 2019 , 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 $ 7,382 $ 7,408 Due after one year through five years 0 0 52,075 53,189 Due after five years through ten years 4,756 5,417 144,626 149,961 Due after ten years 6,258 6,370 528,939 547,578 Mortgage-backed securities - residential 20,818 20,766 421,945 431,555 Mortgage-backed securities - commercial 101,267 100,613 474,174 476,518 Collateralized mortgage obligations 9,763 9,655 769,076 785,444 Asset-backed securities 0 0 400,081 400,431 Total $ 142,862 $ 142,821 $ 2,798,298 $ 2,852,084
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, 2019 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 $ 0 $ 0 $ 0 $ 0 Securities of U.S. government agencies and corporations 0 0 0 0 0 0 Mortgage-backed securities - residential 40,190 (209 ) 11,063 (64 ) 51,253 (273 ) Mortgage-backed securities - commercial 111,658 (298 ) 104,069 (3,571 ) 215,727 (3,869 ) Collateralized mortgage obligations 85,248 (297 ) 30,628 (196 ) 115,876 (493 ) Obligations of state and other political subdivisions 118,623 (457 ) 7,950 (36 ) 126,573 (493 ) Asset-backed securities 125,889 (553 ) 54,963 (511 ) 180,852 (1,064 ) Other securities 0 0 5,649 (115 ) 5,649 (115 ) Total $ 481,608 $ (1,814 ) $ 214,322 $ (4,493 ) $ 695,930 $ (6,307 ) December 31, 2018 Less than 12 months 12 months or more Total (Dollars in thousands) Fair Unrealized Fair Unrealized Fair Unrealized 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 )

LOANS (Tables)

LOANS (Tables)	12 Months Ended
	Dec. 31, 2019
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, 2019 Real Estate (Dollars in thousands) Commercial & industrial Construction Commercial Lease financing Total Pass $ 2,324,021 $ 493,182 $ 4,108,752 $ 85,262 $ 7,011,217 Special Mention 100,954 0 59,383 488 160,825 Substandard 40,902 0 26,516 2,614 70,032 Doubtful 0 0 0 0 0 Total $ 2,465,877 $ 493,182 $ 4,194,651 $ 88,364 $ 7,242,074 Residential real estate Home equity Installment Credit card Total Performing $ 1,040,787 $ 766,169 $ 82,385 $ 48,983 $ 1,938,324 Nonperforming 15,162 5,700 204 201 21,267 Total $ 1,055,949 $ 771,869 $ 82,589 $ 49,184 $ 1,959,591 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
Loan Delinquency, including Nonaccrual Loans	Loan delinquency, including nonaccrual loans, was as follows: As of December 31, 2019 (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 $ 1,266 $ 3,332 $ 14,518 $ 19,116 $ 2,443,680 $ 2,462,796 $ 3,081 $ 2,465,877 $ 0 Lease financing 0 0 0 0 88,364 88,364 0 88,364 0 Construction real estate 0 0 0 0 493,167 493,167 15 493,182 0 Commercial real estate 776 857 5,613 7,246 4,151,513 4,158,759 35,892 4,194,651 0 Residential real estate 8,032 1,928 5,031 14,991 1,014,138 1,029,129 26,820 1,055,949 0 Home equity 2,530 1,083 2,795 6,408 762,863 769,271 2,598 771,869 0 Installment 111 50 148 309 82,022 82,331 258 82,589 0 Credit card 208 75 201 484 48,700 49,184 0 49,184 201 Total $ 12,923 $ 7,325 $ 28,306 $ 48,554 $ 9,084,447 $ 9,133,001 $ 68,664 $ 9,201,665 $ 201 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
Loans Restructured During Period	The following table provides information on loan modifications classified as TDRs during the years ended December 31, 2019 , 2018 and 2017 : Years ended December 31, 2019 2018 2017 (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 8 $ 25,009 $ 25,071 17 $ 23,943 $ 23,890 7 $ 5,724 $ 5,661 Construction real estate 0 0 0 0 0 0 0 0 0 Commercial real estate 9 3,024 2,932 8 3,385 3,150 8 1,816 1,758 Residential real estate 30 3,415 3,062 13 1,148 1,073 6 416 315 Home equity 14 395 366 5 95 192 1 39 39 Installment 2 41 39 0 0 0 0 0 0 Total 63 $ 31,884 $ 31,470 43 $ 28,571 $ 28,305 22 $ 7,995 $ 7,773
Loans Restructured, Modifications	The following table provides information on how TDRs were modified during the years ended December 31, 2019 , 2018 and 2017 : Years Ended December 31, (Dollars in thousands) 2019 2018 2017 Extended maturities $ 2,877 $ 4,093 $ 3,261 Adjusted interest rates 5,284 52 2,767 Combination of rate and maturity changes 516 0 489 Forbearance 20,320 23,175 1,181 Other (1) 2,473 985 75 Total $ 31,470 $ 28,305 $ 7,773 (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) 2019 2018 2017 Impaired loans Nonaccrual loans (1) Commercial & industrial $ 24,346 $ 30,925 $ 5,229 Lease financing 223 22 82 Construction real estate 0 9 29 Commercial real estate 7,295 20,500 10,616 Residential real estate 10,892 13,495 4,140 Home equity 5,242 5,580 3,743 Installment 167 169 243 Total nonaccrual loans 48,165 70,700 24,082 Accruing troubled debt restructurings 11,435 16,109 17,545 Total impaired loans $ 59,600 $ 86,809 $ 41,627 Interest income effect Gross amount of interest that would have been recorded under original terms $ 5,813 $ 4,656 $ 3,397 Interest included in income Nonaccrual loans 1,042 715 535 Troubled debt restructurings 801 642 710 Total interest included in income 1,843 1,357 1,245 Net impact on interest income $ 3,970 $ 3,299 $ 2,152 Commitments outstanding to borrowers with nonaccrual loans $ 3 $ 200 $ 0 (1) Nonaccrual loans include nonaccrual TDRs of $18.5 million , $22.4 million and $6.4 million as of December 31, 2019 , 2018 and 2017 , respectively.
Investment in Impaired Loans	First Financial's investment in impaired loans, excluding purchased impaired loans, is as follows: December 31, 2019 December 31, 2018 (Dollars in thousands) Current balance Contractual principal balance Related allowance Current balance Contractual Related Loans with no related allowance recorded Commercial & industrial $ 16,726 $ 19,709 $ 0 $ 36,694 $ 42,561 $ 0 Lease financing 223 223 0 22 22 0 Construction real estate 0 0 0 9 26 0 Commercial real estate 10,160 17,897 0 23,513 31,375 0 Residential real estate 14,868 17,368 0 17,297 19,975 0 Home equity 5,700 6,462 0 6,351 7,461 0 Installment 204 341 0 174 563 0 Total 47,881 62,000 0 84,060 101,983 0 Loans with an allowance recorded Commercial & industrial 10,754 21,513 2,044 939 939 667 Lease financing 0 0 0 0 0 0 Construction real estate 0 0 0 0 0 0 Commercial real estate 671 675 113 1,509 1,509 461 Residential real estate 294 294 18 301 301 32 Home equity 0 0 0 0 0 0 Installment 0 0 0 0 0 0 Total 11,719 22,482 2,175 2,749 2,749 1,160 Total Commercial & industrial 27,480 41,222 2,044 37,633 43,500 667 Lease financing 223 223 0 22 22 0 Construction real estate 0 0 0 9 26 0 Commercial real estate 10,831 18,572 113 25,022 32,884 461 Residential real estate 15,162 17,662 18 17,598 20,276 32 Home equity 5,700 6,462 0 6,351 7,461 0 Installment 204 341 0 174 563 0 Total $ 59,600 $ 84,482 $ 2,175 $ 86,809 $ 104,732 $ 1,160 Years ended December 31, 2019 2018 2017 (Dollars in thousands) Average balance Interest Average balance Interest income recognized Average Interest Loans with no related allowance recorded Commercial & industrial $ 31,846 $ 926 $ 14,498 $ 360 $ 13,167 $ 280 Lease financing 168 0 21 0 112 4 Construction real estate 6 0 20 2 601 1 Commercial real estate 18,757 357 24,738 490 20,935 563 Residential real estate 15,915 307 11,359 301 7,616 196 Home equity 5,893 121 5,541 114 4,032 99 Installment 170 2 274 2 332 4 Total 72,755 1,713 56,451 1,269 46,795 1,147 Loans with an allowance recorded Commercial & industrial 4,721 87 900 44 1,204 28 Lease financing 57 0 0 0 0 0 Construction real estate 0 0 0 0 0 0 Commercial real estate 1,339 31 1,402 18 2,634 40 Residential real estate 446 12 895 23 1,112 26 Home equity 0 0 80 3 101 4 Installment 0 0 0 0 0 0 Total 6,563 130 3,277 88 5,051 98 Total Commercial & industrial 36,567 1,013 15,398 404 14,371 308 Lease financing 225 0 21 0 112 4 Construction real estate 6 0 20 2 601 1 Commercial real estate 20,096 388 26,140 508 23,569 603 Residential real estate 16,361 319 12,254 324 8,728 222 Home equity 5,893 121 5,621 117 4,133 103 Installment 170 2 274 2 332 4 Total $ 79,318 $ 1,843 $ 59,728 $ 1,357 $ 51,846 $ 1,245
Changes in Other Real Estate Owned	Changes in OREO were as follows: Years ended December 31, (Dollars in thousands) 2019 2018 2017 Balance at beginning of year $ 1,401 $ 2,781 $ 6,284 Additions Commercial 415 1,269 1,732 Residential 2,033 1,913 2,387 Total additions 2,448 3,182 4,119 Disposals Commercial (541 ) (2,967 ) (5,409 ) Residential (912 ) (830 ) (1,574 ) Total disposals (1,453 ) (3,797 ) (6,983 ) Valuation adjustments Commercial (112 ) (355 ) (439 ) Residential (251 ) (410 ) (200 ) Total valuation adjustments (363 ) (765 ) (639 ) Balance at end of year $ 2,033 $ 1,401 $ 2,781

ALLOWANCE FOR LOAN AND LEASE _2

ALLOWANCE FOR LOAN AND LEASE LOSSES (Tables)	12 Months Ended
	Dec. 31, 2019
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: 2019 (Dollars in thousands) Commercial & industrial Lease financing Construction real estate Commercial real estate Residential real estate Home equity Installment Credit card Total Allowance for loan and lease losses Balance at beginning of year $ 18,746 $ 1,130 $ 3,413 $ 21,048 $ 4,964 $ 5,348 $ 362 $ 1,531 $ 56,542 Provision for loan and lease losses 23,631 3 (1,100 ) 5,107 739 695 2 1,521 30,598 Gross charge-offs (26,676 ) (162 ) 0 (3,689 ) (677 ) (2,591 ) (223 ) (1,547 ) (35,565 ) Recoveries 2,883 0 68 1,113 273 1,335 251 152 6,075 Total net charge-offs (23,793 ) (162 ) 68 (2,576 ) (404 ) (1,256 ) 28 (1,395 ) (29,490 ) Ending allowance for loan and lease losses $ 18,584 $ 971 $ 2,381 $ 23,579 $ 5,299 $ 4,787 $ 392 $ 1,657 $ 57,650 2018 (Dollars in thousands) Commercial & industrial Lease financing Construction real estate Commercial real estate Residential real estate 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 (Dollars in thousands) Commercial & industrial Lease financing Construction real estate Commercial real estate Residential real estate 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
Allowance for Loan and Lease Losses by Classification	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, 2019 (Dollars in thousands) Commercial & industrial Lease financing Construction real estate Commercial real estate Residential real estate Home equity Installment Credit card Total Ending allowance on loans individually evaluated for impairment $ 2,044 $ 0 $ 0 $ 113 $ 18 $ 0 $ 0 $ 0 $ 2,175 Ending allowance on loans collectively evaluated for impairment 16,540 971 2,381 23,466 5,281 4,787 392 1,657 55,475 Ending allowance for loan and lease losses $ 18,584 $ 971 $ 2,381 $ 23,579 $ 5,299 $ 4,787 $ 392 $ 1,657 $ 57,650 Loans and Leases Ending balance of loans individually evaluated for impairment $ 27,480 $ 223 $ 0 $ 10,831 $ 15,162 $ 5,700 $ 204 $ 0 $ 59,600 Ending balance of loans collectively evaluated for impairment 2,438,397 88,141 493,182 4,183,820 1,040,787 766,169 82,385 49,184 9,142,065 Total loans $ 2,465,877 $ 88,364 $ 493,182 $ 4,194,651 $ 1,055,949 $ 771,869 $ 82,589 $ 49,184 $ 9,201,665 December 31, 2018 (Dollars in thousands) Commercial & industrial Lease financing Construction real estate Commercial real estate Residential real estate 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

PREMISES AND EQUIPMENT (Tables)

PREMISES AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Table Text Block]	Premises and equipment at December 31 were as follows: (Dollars in thousands) 2019 2018 Land and land improvements $ 54,958 $ 57,701 Buildings 163,277 161,817 Furniture and fixtures 74,881 66,567 Leasehold improvements 31,728 29,086 Construction in progress 4,096 5,731 328,940 320,902 Less: Accumulated depreciation and amortization 114,434 105,250 Total $ 214,506 $ 215,652

LEASES LEASES (Tables)

LEASES LEASES (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Lease, Cost [Table Text Block]	The components of lease expense were as follows: Year ended (dollars in thousands) December 31, 2019 Operating lease cost $ 7,324 Short-term lease cost 55 Variable lease cost 2,553 Total operating lease cost $ 9,932
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	Future minimum commitments due under these lease agreements as of December 31, 2019 are as follows: (dollars in thousands) Operating leases 2020 $ 7,200 2021 7,166 2022 6,640 2023 6,711 2024 6,457 Thereafter 50,504 Total lease payments 84,678 Less imputed interest 20,401 Total $ 64,277
Schedule of supplemental balance sheet information related to leases. [Table Text Block]	The lease term and discount rate at December 31, 2019 were as follows: Operating leases Weighted-average remaining lease term 15.6 years Weighted-average discount rate 3.43 %
Schedule of supplemental cash flow information related to leases [Table Text Block]	Supplemental cash information at December 31, 2019 related to leases was as follows: Year ended (dollars in thousands) December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 7,335 ROU assets obtained in exchange for lease obligations Operating leases 64,902

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS GOODWILL (Tables)	12 Months Ended
	Dec. 31, 2019
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, 2019 , 2018 and 2017 are shown below. (Dollars in thousands) 2019 2018 2017 Balance at beginning of year $ 880,251 $ 204,084 $ 204,084 Goodwill resulting from business combinations 57,520 676,167 0 Balance at end of year $ 937,771 $ 880,251 $ 204,084
Schedule of Finite-Lived Intangible Assets	The gross carrying amount and accumulated amortization of other intangible assets at December 31, 2019 and December 31, 2018 were as follows: (Dollars in thousands) December 31, 2019 December 31, 2018 Amortized intangible assets Core deposit intangibles $ 51,031 $ (21,149 ) $ 54,357 $ (16,500 ) Customer list 39,420 (1,195 ) 0 0 Other 10,093 (1,999 ) 3,763 (815 ) Total $ 100,544 $ (24,343 ) $ 58,120 $ (17,315 )
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The estimated amortization expense of intangible assets for the next five years is as follows: (Dollars in thousands) Intangible amortization 2020 $ 11,670 2021 10,263 2022 7,718 2023 6,739 2024 6,670

DEPOSITS (Tables)

DEPOSITS (Tables)	12 Months Ended
	Dec. 31, 2019
Deposits [Abstract]
Maturities of time deposits [Table Text Block]	Scheduled maturities of all time deposits for the next five years were as follows: (Dollars in thousands) Time deposits 2020 $ 1,752,552 2021 294,579 2022 141,261 2023 37,757 2024 13,272 Thereafter 1,020 Total $ 2,240,441

BORROWINGS (Tables)

BORROWINGS (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule Of Remaining Contractual Maturity Of Secured Borrowings And Class Of Collateral Pledged Under Repurchase Agreements Table [Table Text Block]	The following shows the remaining contractual maturity of repurchase agreements by collateral pledged: (Dollars in thousands) Overnight and Continuous Repurchase agreements Mortgage-backed securities $ 9,755 Collateralized mortgage obligations 80,426 Total $ 90,181
Schedule of Short-term Debt [Table Text Block]	The following is a summary of short-term borrowings for the last three years: 2019 2018 2017 (Dollars in thousands) Amount Rate Amount Rate Amount Rate At December 31, Federal funds purchased and securities sold under agreements to repurchase $ 165,181 0.85 % $ 183,591 1.65 % $ 72,265 0.19 % FHLB borrowings 1,151,000 1.73 % 857,100 2.48 % 742,300 1.43 % Total $ 1,316,181 1.62 % $ 1,040,691 2.33 % $ 814,565 1.32 % Average for the year Federal funds purchased and securities sold under agreements to repurchase $ 155,859 1.15 % $ 87,221 0.58 % $ 69,766 0.19 % FHLB borrowings 990,860 2.37 % 857,028 2.03 % 760,558 1.05 % Other short-term borrowings 0 0.00 % 3,178 4.36 % 41 4.07 % Total $ 1,146,719 1.90 % $ 947,427 1.90 % $ 830,365 0.98 % Maximum month-end balances Federal funds purchased and securities sold under agreements to repurchase $ 260,621 $ 183,591 $ 130,633 FHLB borrowings 1,171,400 1,170,800 957,700 Other short-term borrowings 0 10,000 0
Summary of Long-term Debt [Table Text Block]	The following is a summary of First Financial's long-term debt: 2019 2018 (Dollars in thousands) Amount Average Rate Amount Average Rate FHLB borrowings $ 242,428 1.94 % $ 400,599 2.08 % Subordinated debt 170,967 4.97 % 170,550 5.28 % Unamortized debt issuance costs (1,007 ) n/a (1,185 ) n/a Capital lease liability 1,213 4.48 % 0 0.00 % Capital loan with municipality 775 0.00 % 775 0.00 % Total long-term debt $ 414,376 3.20 % $ 570,739 3.04 %
Schedule of Maturities of Long-term Debt [Table Text Block]	As of December 31, 2019 , First Financial's long-term debt matures as follows: (Dollars in thousands) Long-term debt 2020 $ 104,059 2021 19,052 2022 49,451 2023 49 2024 51 Thereafter 241,714 Total $ 414,376

DERIVATIVES (Tables)

DERIVATIVES (Tables)	12 Months Ended
	Dec. 31, 2019
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, 2019 December 31, 2018 Estimated fair value Estimated fair value (Dollars in thousands) Balance Sheet Classification Notional amount Gain Loss Notional amount Gain Loss Client derivatives-instruments associated with loans Matched interest rate swaps with borrower Accrued interest and other assets and other liabilities $ 1,923,375 $ 70,799 $ (2,636 ) $ 1,359,990 $ 17,402 $ (11,787 ) Matched interest rate swaps with counterparty Accrued interest and other liabilities 1,923,375 2,636 (70,808 ) 1,359,990 11,787 (17,401 ) Foreign exchange contracts Matched foreign exchange contracts with customers Accrued interest and other assets 1,869,934 28,739 (10,433 ) 0 0 0 Match foreign exchange contracts with counterparty Accrued interest and other liabilities 1,869,934 10,433 (28,739 ) 0 0 0 Total $ 7,586,618 $ 112,607 $ (112,616 ) $ 2,719,980 $ 29,189 $ (29,188 )
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, 2019 December 31, 2018 (Dollars in thousands) Gross amounts of recognized liabilities Gross amounts offset in the Consolidated Balance Sheets Net amounts of (assets)/liabilities presented in the Consolidated Balance Sheets Gross amounts of recognized liabilities Gross amounts offset in the Consolidated Balance Sheets Net amounts of (assets)/liabilities presented in the Consolidated Balance Sheets Client derivatives Matched interest rate swaps $ 73,444 $ (147,193 ) $ (73,749 ) $ 29,189 $ (14,577 ) $ 14,612 Foreign exchange contracts with counterparty 39,172 (41,202 ) (2,030 ) 0 0 0 Total $ 112,616 $ (188,395 ) $ (75,779 ) $ 29,189 $ (14,577 ) $ 14,612
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, 2019 : (Dollars in thousands) Notional amount Average maturity (years) Fair value Client derivatives-interest rate contracts Receive fixed, matched interest rate swaps with borrower $ 1,923,375 6.0 $ 68,163 Pay fixed, matched interest rate swaps with counterparty 1,923,375 6.0 (68,172 ) Client derivatives-foreign exchange contracts Foreign exchange contracts - pay USD 1,869,934 0.6 18,306 Foreign exchange contracts - receive USD 1,869,934 0.6 (18,306 ) Total client derivatives $ 7,586,618 3.3 $ (9 )

RELATED PARTIES TRANSACTIONS (T

RELATED PARTIES TRANSACTIONS (Tables)	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Schedule of Loans to Related Parties [Table Text Block]	oans to directors, executive officers, principal holders of First Financial’s common stock and certain related persons were as follows: (Dollars in thousands) 2019 Beginning balance $ 2,732 Additions 4,348 Deductions (1,791 ) Ending balance $ 5,289 Loans 90 days or more past due $ 0

INCOME TAXES INCOME TAXES (Tabl

INCOME TAXES INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2019
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) 2019 2018 2017 Current expense Federal $ 31,343 $ 34,330 $ 22,599 State 854 1,029 1,265 Total current expense 32,197 35,359 23,864 Deferred expense (benefit) Federal 10,946 4,675 (4,657 ) State 1,644 1,592 169 Total deferred expense (benefit) 12,590 6,267 (4,488 ) Income tax expense $ 44,787 $ 41,626 $ 19,376
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) 2019 2018 2017 Income taxes computed at federal statutory rate on income before income taxes (21% in 2019 and 2018; 35% in 2017) $ 51,001 $ 44,986 $ 40,657 Benefit from tax-exempt income (5,964 ) (4,499 ) (3,427 ) Tax credits (10,075 ) (5,439 ) (16,806 ) Tax rate reduction impact 0 0 (8,191 ) Basis reduction on tax credit 738 0 4,599 Tax benefit of equity compensation (140 ) (565 ) (1,449 ) State income taxes, net of federal tax benefit 1,973 2,070 932 Affordable housing investments 5,825 4,725 2,798 Other 1,429 348 263 Income tax expense $ 44,787 $ 41,626 $ 19,376
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, 2019 , and 2018 , were as follows: (Dollars in thousands) 2019 2018 Deferred tax assets Allowance for loan and lease losses $ 13,011 $ 12,782 Fair value adjustments on business combinations 6,470 11,199 Deferred compensation 228 392 Postretirement benefits other than pension liability 666 676 Accrued stock-based compensation 1,296 1,145 OREO write-downs 162 118 Interest on nonaccrual loans 548 1,160 Accrued expenses 4,708 5,808 Net unrealized losses on investment securities and derivatives 0 3,221 State net operating loss 2,792 3,119 Leasing liability 14,806 0 Federal tax credit carryforwards 0 873 Other 816 425 Total deferred tax assets 45,503 40,918 Deferred tax liabilities Tax depreciation in excess of book depreciation (10,970 ) (9,530 ) FHLB and FRB stock (4,043 ) (4,044 ) Mortgage-servicing rights (2,435 ) (2,285 ) Leasing activities (7,349 ) (3,881 ) Retirement obligation (8,511 ) (6,614 ) Intangible assets (11,647 ) (12,310 ) Deferred loan fees and costs (1,100 ) (131 ) Prepaid expenses (623 ) (582 ) Limited partnership investments (2,249 ) (2,367 ) Net unrealized gains on investment securities (11,359 ) 0 Foreign exchange deferred income (2,845 ) 0 Right of use assets (13,354 ) 0 Other (2,048 ) (1,867 ) Total deferred tax liabilities (78,533 ) (43,611 ) Total net deferred tax liability $ (33,030 ) $ (2,693 )
Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table Text Block]	A progression of gross unrecognized tax benefits as of December 31, 2019 and 2018 is as follows: (Dollars in thousands) 2019 2018 Balance at beginning of year $ 3,735 $ 3,735 Settlements (729 ) 0 Balance at end of year $ 3,006 $ 3,735

EMPLOYEE BENEFIT PLANS (Tables)

EMPLOYEE BENEFIT PLANS (Tables)	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
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) 2019 2018 Change in benefit obligation Benefit obligation at beginning of year $ 68,286 $ 71,154 Service cost 6,591 6,501 Interest cost 2,778 2,394 Actuarial (gain) loss 6,848 (4,032 ) Benefits paid, excluding settlement (9,459 ) (7,731 ) Benefit obligation at end of year 75,044 68,286 Change in plan assets Fair value of plan assets at beginning of year 130,078 144,349 Actual return on plan assets 21,197 (6,540 ) Benefits paid, excluding settlement (9,459 ) (7,731 ) Fair value of plan assets at end of year 141,816 130,078 Amounts recognized in the Consolidated Balance Sheets Assets 66,772 61,792 Liabilities 0 0 Net amount recognized $ 66,772 $ 61,792 Amounts recognized in accumulated other comprehensive income (loss) Net actuarial loss $ 37,278 $ 43,711 Net prior service cost (1,095 ) (1,508 ) Deferred tax assets (8,242 ) (9,613 ) Net amount recognized $ 27,941 $ 32,590 Change in accumulated other comprehensive income (loss) $ (4,649 ) $ 12,959 Accumulated benefit obligation $ 74,424 $ 66,320
Schedule of Components of Net Periodic Benefit Cost [Table Text Block]	The components of net periodic benefit cost are shown in the table that follows: December 31, (Dollars in thousands) 2019 2018 2017 Service cost $ 6,591 $ 6,501 $ 4,894 Interest cost 2,778 2,394 2,325 Expected return on assets (9,718 ) (9,811 ) (9,358 ) Amortization of prior service cost (413 ) (413 ) (413 ) Recognized net actuarial loss 1,803 2,188 1,924 Net periodic benefit (income) cost 1,041 859 (628 ) Other changes recognized in accumulated other comprehensive income (loss) Net actuarial (gain) loss (4,630 ) 12,319 (2,775 ) Prior service cost 0 0 0 Amortization of prior service cost 413 413 413 Amortization of gain (1,803 ) (2,188 ) (1,924 ) Total recognized in accumulated other comprehensive income (loss) (6,020 ) 10,544 (4,286 ) Total recognized in net periodic benefit cost and accumulated other comprehensive income (loss) $ (4,979 ) $ 11,403 $ (4,914 ) Amount expected to be recognized in net periodic pension expense in the coming year Amortization of (gain) loss $ 2,079 $ 1,867 $ 2,090 Amortization of prior service credit (413 ) (413 ) (413 )
Defined Benefit Plan, Assumptions [Table Text Block]	The pension plan assumptions are shown in the table that follows: December 31, 2019 2018 2017 Benefit obligations Discount rate 3.33 % 4.31 % 3.43 % Rate of compensation increase 3.50 % 3.50 % 3.50 % Net periodic benefit cost Discount rate 4.31 % 3.43 % 3.88 % Expected return on plan assets 7.25 % 7.25 % 7.25 % 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, 2019 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 $ 195 $ 195 $ 0 $ 0 U. S. Government agencies 5,357 0 5,357 0 Fixed income mutual funds 75,720 75,720 0 0 Equity mutual funds 60,544 60,544 0 0 Total $ 141,816 $ 136,459 $ 5,357 $ 0 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
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) Expected benefit payments 2020 $ 5,611 2021 5,210 2022 5,173 2023 5,125 2024 6,070 Thereafter 35,362

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	12 Months Ended
	Dec. 31, 2019
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, 2019 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 $ 65,858 $ (370 ) $ 66,228 $ (14,269 ) $ 51,959 $ (11,601 ) $ 51,959 $ 906 $ 41,264 Unrealized gain (loss) on derivatives 281 0 281 (64 ) 217 (217 ) 217 0 0 Retirement obligation 4,630 (1,390 ) 6,020 (1,371 ) 4,649 (32,590 ) 4,649 0 (27,941 ) Total $ 70,769 $ (1,760 ) $ 72,529 $ (15,704 ) $ 56,825 $ (44,408 ) $ 56,825 $ 906 $ 13,323 December 31, 2018 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 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 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 $ 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 )
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) 2019 2018 2017 Affected Line Item in the Consolidated Statements of Income Realized gains and losses on securities available-for-sale $ (370 ) $ (161 ) $ 1,649 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) (1,803 ) (2,188 ) (1,924 ) Other noninterest expense Amortization and settlement charges of defined benefit pension items (1,390 ) (1,775 ) (1,511 ) Total reclassifications for the period, before tax $ (1,760 ) $ (1,936 ) $ 138 (1) Negative amounts are debits to profit/loss. (2) Included in the computation of net periodic pension cost (see Note 16 - Employee Benefit Plans for additional details).

CAPITAL (Tables)

CAPITAL (Tables)	12 Months Ended
	Dec. 31, 2019
Banking and Thrift [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block]	Actual Minimum capital PCA requirement to be (Dollars in thousands) Capital Ratio Capital Ratio Capital Ratio December 31, 2019 Common equity tier 1 capital to risk-weighted assets Consolidated $ 1,245,746 11.30 % $ 771,666 7.00 % N/A N/A First Financial Bank 1,333,978 12.11 % 770,997 7.00 % $ 715,926 6.50 % Tier 1 capital to risk-weighted assets Consolidated 1,288,185 11.69 % 937,023 8.50 % N/A N/A First Financial Bank 1,334,082 12.11 % 936,211 8.50 % $ 881,140 8.00 % Total capital to risk-weighted assets Consolidated 1,475,813 13.39 % 1,157,498 10.50 % N/A N/A First Financial Bank 1,399,817 12.71 % 1,156,496 10.50 % 1,101,425 10.00 % Leverage Consolidated 1,288,185 9.58 % 537,606 4.00 % N/A N/A First Financial Bank 1,334,082 9.93 % 537,299 4.00 % 671,623 5.00 % Actual Minimum capital PCA requirement 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 6.38 % N/A N/A $ 716,881 7.00 % First Financial Bank 1,279,492 12.50 % 652,590 6.38 % $ 665,386 6.50 % 716,570 7.00 % Tier 1 capital to risk-weighted assets Consolidated 1,257,366 12.28 % 806,491 7.88 % N/A N/A 870,499 8.50 % First Financial Bank 1,279,596 12.50 % 806,141 7.88 % 818,937 8.00 % 870,120 8.50 % Total capital to risk-weighted assets Consolidated 1,444,146 14.10 % 1,011,314 9.88 % N/A N/A 1,075,322 10.50 % First Financial Bank 1,344,388 13.13 % 1,010,875 9.88 % 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 %

STOCK OPTIONS AND AWARDS (Table

STOCK OPTIONS AND AWARDS (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Share-based Payment Arrangement, Option, Activity [Table Text Block]	Stock option activity for the year ended December 31, 2019 , 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 62,410 $ 9.08 Granted 0 0.00 Exercised (24,554 ) 8.37 Forfeited or expired 0 0.00 Outstanding at end of year 37,856 $ 9.54 3.12 $ 602 Exercisable at end of year 37,856 $ 9.54 3.12 $ 602
Schedule of Cash Proceeds Received from Share-based Payment Awards [Table Text Block] (Deprecated 2017-01-31)	2019 2018 2017 Total intrinsic value of options exercised $ 462 $ 734 $ 1,533 Cash received from exercises $ 90 $ 284 $ 341 Tax benefit from exercises $ 1,844 $ 1,439 $ 1,991
Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]	Activity in restricted stock for the previous three years ended December 31 is summarized as follows: 2019 2018 2017 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 462,446 $ 26.39 468,372 $ 21.63 648,817 $ 17.82 Granted 395,023 26.55 303,930 28.94 234,529 27.36 Vested (295,633 ) 24.94 (267,031 ) 20.94 (307,825 ) 18.12 Forfeited (31,267 ) 28.63 (42,825 ) 26.38 (107,149 ) 21.18 Nonvested at end of year 530,569 $ 27.19 462,446 $ 26.39 468,372 $ 21.63

EARNINGS PER COMMON SHARE (Tabl

EARNINGS PER COMMON SHARE (Tables)	12 Months Ended
	Dec. 31, 2019
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) 2019 2018 2017 Numerator Net income $ 198,075 $ 172,595 $ 96,787 Denominator Basic earnings per common share - weighted average shares 98,305,570 88,582,090 61,529,460 Effect of dilutive securities Employee stock awards 545,901 514,680 581,329 Warrants 0 517,435 60,801 Diluted earnings per common share - adjusted weighted average shares 98,851,471 89,614,205 62,171,590 Earnings per share available to common shareholders Basic $ 2.01 $ 1.95 $ 1.57 Diluted $ 2.00 $ 1.93 $ 1.56

FAIR VALUE DISCLOSURES (Tables)

FAIR VALUE DISCLOSURES (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Estimated Fair Values of Financial Instruments	The estimated fair values of First Financial's financial instruments not measured at fair value on a recurring or nonrecurring basis in the consolidated financial statements were as follows: Carrying Estimated fair value (Dollars in thousands) value Total Level 1 Level 2 Level 3 December 31, 2019 Financial assets Cash and short-term investments $ 257,639 $ 257,639 $ 257,639 $ 0 $ 0 Investment securities held-to-maturity 142,862 142,821 0 142,821 0 Other investments 125,020 N/A N/A N/A N/A Loans held for sale 13,680 13,680 0 13,680 0 Loans and leases 9,144,015 9,134,215 0 0 9,134,215 Accrued interest receivable 39,591 39,591 0 12,743 26,848 Financial liabilities Deposits 10,210,229 10,209,790 0 10,209,790 0 Short-term borrowings 1,316,181 1,316,181 1,316,181 0 0 Long-term debt 414,376 414,937 0 414,937 0 Accrued interest payable 13,671 13,671 1,899 11,772 0 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 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 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
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, 2019 Assets Investment securities available-for-sale $ 100 $ 2,842,794 $ 9,190 $ 2,852,084 Interest rate derivative contracts 0 73,558 0 73,558 Foreign exchange derivative contracts 0 39,172 0 39,172 Total $ 100 $ 2,955,524 $ 9,190 $ 2,964,814 Liabilities Interest rate derivative contracts $ 0 $ 73,750 $ 0 $ 73,750 Foreign exchange derivative contracts 0 39,172 0 39,172 Total $ 0 $ 112,922 $ 0 $ 112,922 Fair Value Measurements Using Assets/Liabilities (Dollars in thousands) Level 1 Level 2 Level 3 at Fair Value December 31, 2018 Assets Investment securities available-for-sale $ 97 $ 2,764,443 $ 14,715 $ 2,779,255 Derivatives 0 29,543 0 29,543 Total $ 97 $ 2,793,986 $ 14,715 $ 2,808,798 Liabilities Derivatives $ 0 $ 29,336 $ 0 $ 29,336
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation	The following table presents a reconciliation for certain AFS securities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the year ended December 31, 2019 . Year ended (dollars in thousands) December 31, 2019 Beginning balance $ 14,715 Accretion (amortization) (552 ) Increase (decrease) in fair value 30 Settlements (5,003 ) Ending balance $ 9,190
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, 2019 Assets Impaired loans $ 0 $ 0 $ 9,268 OREO 0 0 1,088 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

BUSINESS COMBINATIONS (Tables)

BUSINESS COMBINATIONS (Tables)	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table provides the purchase price calculation as of the acquisition date, identifiable assets purchased and liabilities assumed at their estimated fair value for the MSFG merger. 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 71,806 Investment securities available-for-sale 900,935 Investment securities held-to-maturity 171,423 Other investments 28,763 Loans 2,792,572 Premises and equipment 98,814 Intangible assets 42,887 Other assets 167,829 Assets held for sale 127,775 Total assets acquired 4,402,804 Liabilities assumed Deposits 3,263,920 Subordinated notes 49,027 FHLB advances 291,887 Other borrowings 205,620 Other liabilities 32,649 Liabilities held for sale 175,840 Total liabilities assumed 4,018,943 Net identifiable assets 383,861 Goodwill $ 675,643
Business Acquisition, Pro Forma Information, Nonrecurring Adjustments	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, 2019
Condensed Financial Information Disclosure [Abstract]
Schedule of Condensed Balance Sheet	Balance Sheets December 31, (Dollars in thousands) 2019 2018 Assets Cash $ 55,869 $ 86,878 Investment securities 1,116 694 Subordinated notes from subsidiaries 7,500 7,500 Investment in subsidiaries Commercial bank 2,272,991 2,078,655 Non-banks 8,260 7,194 Total investment in subsidiaries 2,281,251 2,085,849 Premises and equipment 1,344 1,361 Other assets 77,572 71,817 Total assets $ 2,424,652 $ 2,254,099 Liabilities Subordinated notes $ 171,983 $ 171,416 Dividends payable 849 465 Other liabilities 4,115 3,969 Total liabilities 176,947 175,850 Shareholders’ equity 2,247,705 2,078,249 Total liabilities and shareholders’ equity $ 2,424,652 $ 2,254,099
Schedule of Condensed Income Statement	Statements of Income and Comprehensive Income Years Ended December 31, (Dollars in thousands) 2019 2018 2017 Income Interest income $ 30 $ 23 $ 6 Noninterest income 191 0 86 Dividends from subsidiaries 196,800 107,340 54,600 Total income 197,021 107,363 54,692 Expenses Interest expense 9,552 8,798 6,152 Salaries and employee benefits 8,169 6,413 5,519 Professional services 1,040 5,130 970 Other 6,599 5,648 4,819 Total expenses 25,360 25,989 17,460 Income before income taxes and equity in undistributed net earnings of subsidiaries 171,661 81,374 37,232 Income tax expense (benefit) (5,975 ) (6,687 ) (7,080 ) Equity in undistributed earnings (loss) of subsidiaries 20,439 84,534 52,475 Net income $ 198,075 $ 172,595 $ 96,787 Comprehensive income $ 254,900 $ 153,670 $ 104,840
Schedule of Condensed Cash Flow Statement	Statements of Cash Flows Years Ended December 31, (Dollars in thousands) 2019 2018 2017 Operating activities Net income $ 198,075 $ 172,595 $ 96,787 Adjustments to reconcile net income to net cash provided by operating activities Equity in undistributed (earnings) loss of subsidiaries (20,439 ) (84,534 ) (52,475 ) Depreciation and amortization 584 194 193 Stock-based compensation expense 7,969 6,219 5,446 Deferred income taxes 1,255 739 (360 ) (Decrease) increase in dividends payable 384 (10,500 ) 579 Increase (decrease) in other liabilities (244 ) 9,979 (889 ) Decrease (increase) in other assets (7,187 ) 16,346 (6,951 ) Net cash provided by (used in) operating activities 180,397 111,038 42,330 Investing activities Capital contributions to subsidiaries 0 (3,000 ) 0 Net cash acquired (paid) in business combinations (53,660 ) 11,353 0 Proceeds from sales and maturities of investment securities 264 0 0 Purchases of investment securities (500 ) 0 0 Net cash (used in) provided by investing activities (53,896 ) 8,353 0 Financing activities (Decrease) increase in short-term borrowings 0 (8,333 ) 0 Cash dividends paid on common stock (89,097 ) (79,655 ) (41,178 ) Purchases of common stock (66,218 ) 0 0 Proceeds from exercise of stock options, net of shares purchased 90 284 341 Other (2,285 ) (2,528 ) (3,059 ) Net cash (used in) provided by financing activities (157,510 ) (90,232 ) (43,896 ) Net increase (decrease) in cash (31,009 ) 29,159 (1,566 ) Cash at beginning of year 86,878 57,719 59,285 Cash at end of year $ 55,869 $ 86,878 $ 57,719

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	12 Months Ended
	Dec. 31, 2019USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance threshold for impaired and non-impaired commercial loans	$ 250,000
Commercial & Industrial
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, 2019
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) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Recently Adopted and Issued Accounting Standards [Abstract]
Operating Lease, Right-of-Use Asset			$ 58,600	$ 0	$ 0	$ 60,249
Operating Lease, Liability						$ 65,800
Securities transferred from HTM to AFS	$ 268,700	$ 372,100	268,703	$ 372,128	$ 0
Realized gain (loss) on debt securities transferred from HTM to AFS	$ 200
Allowance for loans and leases losses, range of increase, minimum			115,000
Allowance for loans and leases losses, increase, maximum			125,000
Reserve for unfunded commitments, dollar range of increase, minimum			11,000
Reserve for unfunded commitments, dollar range of increase, maximum			$ 14,000

RESTRICTIONS ON CASH AND DIVI_2

RESTRICTIONS ON CASH AND DIVIDENDS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Restrictions on Subsidiary Dividends, Loans or Advances [Line Items]
Average Restriction on Cash and Due From Bank Accounts	$ 84.1	$ 85.9
Restricted Cash	15.8
Subsidiaries [Member]
Restrictions on Subsidiary Dividends, Loans or Advances [Line Items]
Retained Earnings, Unappropriated	660.7
Amount Available for Dividend Distribution without Affecting Capital Adequacy Requirements	$ 155.7

INVESTMENT SECURITIES INVESTMEN

INVESTMENT SECURITIES INVESTMENTS - Additional Information (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Gain (Loss) on Securities [Line Items]
Proceeds from Sale of Debt Securities, Available-for-sale			$ 519,100	$ 290,700	$ 190,000
Available-for-sale Securities, Gross Realized Gains			2,100	500	1,800
Available-for-sale Securities, Gross Realized Losses			2,100	600	200
Available For Sale Securities Net Realized Gain Loss Tax Provision			0		600
Securities transferred from HTM to AFS	$ 268,700	$ 372,100	268,703	372,128	$ 0
Realized gain (loss) on debt securities transferred from HTM to AFS	$ 200
Pledged Financial Instruments, Not Separately Reported, Securities			$ 1,100,000	$ 1,200,000
NumberOfSecuritiesInSecurityPortfolio			1,273	1,417
NumberOfSecuritiesInUnrealizedLossPosition			140	504

INVESTMENTS - Summary of Held-T

INVESTMENTS - Summary of Held-To-Maturity and Available-For-Sale Investment Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investment Holdings [Line Items]
Total	$ 142,862	$ 429,328
Held To Maturity unrecognized gain	1,497	2,212
Held To Maturity unrecognized loss	1,538	7,422
Held-to-Maturity Market Value	142,821	424,118
Total	2,798,298	2,792,326
Available for Sale unrecognized gain	58,555	9,409
Available for Sale unrecognized loss	4,769	22,480
Investment securities	2,852,084	2,779,255
U.S. Treasuries
Investment Holdings [Line Items]
Total	0	0
Held To Maturity unrecognized gain	0	0
Held To Maturity unrecognized loss	0	0
Held-to-Maturity Market Value	0	0
Total	99	99
Available for Sale unrecognized gain	1	0
Available for Sale unrecognized loss	0	2
Investment securities	100	97
Securities of U.S. government agencies and corporations
Investment Holdings [Line Items]
Total	0	0
Held To Maturity unrecognized gain	0	0
Held To Maturity unrecognized loss	0	0
Held-to-Maturity Market Value	0	0
Total	156	32,095
Available for Sale unrecognized gain	2	57
Available for Sale unrecognized loss	0	233
Investment securities	158	31,919
Mortgage-backed securities-residential
Investment Holdings [Line Items]
Total	20,818	25,565
Held To Maturity unrecognized gain	122	0
Held To Maturity unrecognized loss	174	1,045
Held-to-Maturity Market Value	20,766	24,520
Total	421,945	565,071
Available for Sale unrecognized gain	9,709	691
Available for Sale unrecognized loss	99	7,163
Investment securities	431,555	558,599
Mortgage-backed securities-commercial
Investment Holdings [Line Items]
Total	101,267	147,780
Held To Maturity unrecognized gain	571	258
Held To Maturity unrecognized loss	1,225	4,385
Held-to-Maturity Market Value	100,613	143,653
Total	474,174	423,797
Available for Sale unrecognized gain	4,988	819
Available for Sale unrecognized loss	2,644	3,581
Investment securities	476,518	421,035
Collateralized mortgage obligations
Investment Holdings [Line Items]
Total	9,763	12,540
Held To Maturity unrecognized gain	0	0
Held To Maturity unrecognized loss	108	633
Held-to-Maturity Market Value	9,655	11,907
Total	769,076	928,586
Available for Sale unrecognized gain	16,753	4,319
Available for Sale unrecognized loss	385	6,158
Investment securities	785,444	926,747
Obligations of state and other political subdivisions
Investment Holdings [Line Items]
Total	11,014	243,443
Held To Maturity unrecognized gain	804	1,954
Held To Maturity unrecognized loss	31	1,359
Held-to-Maturity Market Value	11,787	244,038
Total	652,986	257,300
Available for Sale unrecognized gain	23,729	2,554
Available for Sale unrecognized loss	462	1,429
Investment securities	676,253	258,425
Asset-backed Securities
Investment Holdings [Line Items]
Total	0	0
Held To Maturity unrecognized gain	0	0
Held To Maturity unrecognized loss	0	0
Held-to-Maturity Market Value	0	0
Total	400,081	511,430
Available for Sale unrecognized gain	1,414	611
Available for Sale unrecognized loss	1,064	2,810
Investment securities	400,431	509,231
Other securities
Investment Holdings [Line Items]
Total	0	0
Held To Maturity unrecognized gain	0	0
Held To Maturity unrecognized loss	0	0
Held-to-Maturity Market Value	0	0
Total	79,781	73,948
Available for Sale unrecognized gain	1,959	358
Available for Sale unrecognized loss	115	1,104
Investment securities	$ 81,625	$ 73,202

INVESTMENTS - Summary of Invest

INVESTMENTS - Summary of Investment Securities by Estimated Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Held-to-Maturity Amortized Cost
Amortized cost	$ 142,862	$ 429,328
Held-to-Maturity Market Value
Held-to-Maturity Market Value	142,821	424,118
Available-for-Sale Amortized Cost
Amortized Cost	2,798,298	2,792,326
Available-for-Sale Market Value
Investment securities	2,852,084	2,779,255
One Year or Less
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	7,382
Available-for-Sale Market Value
Investment securities	7,408
After One Year Through Five Years
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	52,075
Available-for-Sale Market Value
Investment securities	53,189
After Five Years Through Ten Years
Held-to-Maturity Amortized Cost
Amortized cost	4,756
Held-to-Maturity Market Value
Held-to-Maturity Market Value	5,417
Available-for-Sale Amortized Cost
Amortized Cost	144,626
Available-for-Sale Market Value
Investment securities	149,961
After Ten Years
Held-to-Maturity Amortized Cost
Amortized cost	6,258
Held-to-Maturity Market Value
Held-to-Maturity Market Value	6,370
Available-for-Sale Amortized Cost
Amortized Cost	528,939
Available-for-Sale Market Value
Investment securities	547,578
Mortgage-backed securities-residential
Held-to-Maturity Amortized Cost
Amortized cost	20,818	25,565
Held-to-Maturity Market Value
Held-to-Maturity Market Value	20,766	24,520
Available-for-Sale Amortized Cost
Amortized Cost	421,945	565,071
Available-for-Sale Market Value
Investment securities	431,555	558,599
Mortgage-backed securities-commercial
Held-to-Maturity Amortized Cost
Amortized cost	101,267	147,780
Held-to-Maturity Market Value
Held-to-Maturity Market Value	100,613	143,653
Available-for-Sale Amortized Cost
Amortized Cost	474,174	423,797
Available-for-Sale Market Value
Investment securities	476,518	421,035
Collateralized mortgage obligations
Held-to-Maturity Amortized Cost
Amortized cost	9,763	12,540
Held-to-Maturity Market Value
Held-to-Maturity Market Value	9,655	11,907
Available-for-Sale Amortized Cost
Amortized Cost	769,076	928,586
Available-for-Sale Market Value
Investment securities	785,444	926,747
Asset-backed Securities
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	400,081	511,430
Available-for-Sale Market Value
Investment securities	$ 400,431	$ 509,231

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, 2019	Dec. 31, 2018
Investments, Unrealized Loss Position [Line Items]
Document Period End Date	Dec. 31, 2019
Less than 12 Months Fair Value	$ 481,608	$ 961,572
Less than 12 Months Unrealized Loss	(1,814)	(6,345)
12 Months or More Fair Value	214,322	882,865
12 Months or More Unrealized Loss	(4,493)	(23,557)
Total Fair Value	695,930	1,844,437
Total Unrealized Loss	(6,307)	(29,902)
U.S. Treasuries
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	0	0
Less than 12 Months Unrealized Loss	0	0
12 Months or More Fair Value	0	97
12 Months or More Unrealized Loss	0	(2)
Total Fair Value	0	97
Total Unrealized Loss	0	(2)
Securities of U.S. government agencies and corporations
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	0	0
Less than 12 Months Unrealized Loss	0	0
12 Months or More Fair Value	0	16,777
12 Months or More Unrealized Loss	0	(233)
Total Fair Value	0	16,777
Total Unrealized Loss	0	(233)
Mortgage-backed securities-residential
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	40,190	186,029
Less than 12 Months Unrealized Loss	(209)	(935)
12 Months or More Fair Value	11,063	264,795
12 Months or More Unrealized Loss	(64)	(7,273)
Total Fair Value	51,253	450,824
Total Unrealized Loss	(273)	(8,208)
Mortgage-backed securities-commercial
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	111,658	147,754
Less than 12 Months Unrealized Loss	(298)	(369)
12 Months or More Fair Value	104,069	232,363
12 Months or More Unrealized Loss	(3,571)	(7,597)
Total Fair Value	215,727	380,117
Total Unrealized Loss	(3,869)	(7,966)
Collateralized mortgage obligations
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	85,248	194,795
Less than 12 Months Unrealized Loss	(297)	(1,546)
12 Months or More Fair Value	30,628	240,514
12 Months or More Unrealized Loss	(196)	(5,245)
Total Fair Value	115,876	435,309
Total Unrealized Loss	(493)	(6,791)
Obligations of state and other political subdivisions
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	118,623	62,805
Less than 12 Months Unrealized Loss	(457)	(299)
12 Months or More Fair Value	7,950	86,644
12 Months or More Unrealized Loss	(36)	(2,489)
Total Fair Value	126,573	149,449
Total Unrealized Loss	(493)	(2,788)
Asset-backed Securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	125,889	336,437
Less than 12 Months Unrealized Loss	(553)	(2,312)
12 Months or More Fair Value	54,963	37,105
12 Months or More Unrealized Loss	(511)	(498)
Total Fair Value	180,852	373,542
Total Unrealized Loss	(1,064)	(2,810)
Other securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	0	33,752
Less than 12 Months Unrealized Loss	0	(884)
12 Months or More Fair Value	5,649	4,570
12 Months or More Unrealized Loss	(115)	(220)
Total Fair Value	5,649	38,322
Total Unrealized Loss	$ (115)	$ (1,104)

LOANS - Additional Information

LOANS - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019USD ($)loans	Dec. 31, 2018USD ($)loans	Dec. 31, 2017USD ($)loans	Dec. 31, 2016USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Restructured Loans | loans	157	196	214
Total restructured loans	$ 30,000,000	$ 38,500,000	$ 23,900,000
Restructured Loans, Accrual Status	11,435,000	16,109,000	17,545,000
Restructured Loans, Nonaccrual Status	18,500,000	22,400,000	6,400,000
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend	2,500,000	0	0
Restructured Loans, Allowance for Loan and Lease Losses Included in Reserves	2,500,000	1,500,000	1,300,000
Restructured Loans, Portion Determined to be Uncollectible	2,600,000	900,000	300,000
Accruing TDRs performing in accordance with restructured terms for more than one year	4,700,000	7,900,000	17,200,000
Purchased impaired loans, carrying balance	68,664,000	96,320,000
Real Estate Acquired Through Foreclosure	2,033,000	$ 1,401,000	$ 2,781,000	$ 6,284,000
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, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 9,201,665	$ 8,824,214
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	7,011,217	6,736,493
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	160,825	63,850
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	70,032	111,349
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Commercial & Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,465,877	2,514,661
Commercial & Industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,324,021	2,432,834
Commercial & Industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	100,954	24,594
Commercial & Industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	40,902	57,233
Commercial & Industrial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Construction real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	493,182	548,935
Construction real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	493,182	548,323
Construction real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	603
Construction real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	9
Construction real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	4,194,651	3,754,681
Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	4,108,752	3,664,434
Commercial real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	59,383	38,653
Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	26,516	51,594
Commercial real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	88,364	93,415
Lease financing | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	85,262	90,902
Lease financing | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	488	0
Lease financing | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,614	2,513
Lease financing | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Total commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	7,242,074	6,911,692
Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,055,949	955,646
Residential Real Estate | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,040,787	939,936
Residential Real Estate | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	15,162	15,710
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	771,869	817,282
Home equity | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	766,169	811,108
Home equity | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,700	6,174
Installment
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	82,589	93,212
Installment | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	82,385	93,038
Installment | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	204	174
Credit card
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	49,184	46,382
Credit card | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	48,983	46,382
Credit card | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	201	0
Total consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,959,591	1,912,522
Total consumer loans | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,938,324	1,890,464
Total consumer loans | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 21,267	$ 22,058

LOANS - Loan Delinquency, inclu

LOANS - Loan Delinquency, including Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	$ 48,554	$ 70,190
Current	9,084,447	8,657,704
Loans and Leases Receivable, Gross	9,133,001	8,727,894
Purchased impaired loans, carrying balance	68,664	96,320
Total loans and leases	9,201,665	8,824,214
Greater than 90 days past due and still accruing	201	63
30 to 59 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	12,923	37,266
60 to 89 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	7,325	5,536
Greater than 90 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	28,306	27,388
Commercial & industrial
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	19,116	20,833
Current	2,443,680	2,488,450
Loans and Leases Receivable, Gross	2,462,796	2,509,283
Purchased impaired loans, carrying balance	3,081	5,378
Total loans and leases	2,465,877	2,514,661
Greater than 90 days past due and still accruing	0	0
Commercial & industrial | 30 to 59 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	1,266	13,369
Commercial & industrial | 60 to 89 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	3,332	41
Commercial & industrial | Greater than 90 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	14,518	7,423
Lease financing
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	0	352
Current	88,364	93,063
Loans and Leases Receivable, Gross	88,364	93,415
Purchased impaired loans, carrying balance	0	0
Total loans and leases	88,364	93,415
Greater than 90 days past due and still accruing	0	0
Lease financing | 30 to 59 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	0	352
Lease financing | 60 to 89 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	0	0
Lease financing | Greater than 90 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	0	0
Construction real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	0	0
Current	493,167	548,687
Loans and Leases Receivable, Gross	493,167	548,687
Purchased impaired loans, carrying balance	15	248
Total loans and leases	493,182	548,935
Greater than 90 days past due and still accruing	0	0
Construction real estate | 30 to 59 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	0	0
Construction real estate | 60 to 89 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	0	0
Construction real estate | Greater than 90 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	0	0
Commercial real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	7,246	20,081
Current	4,151,513	3,682,455
Loans and Leases Receivable, Gross	4,158,759	3,702,536
Purchased impaired loans, carrying balance	35,892	52,145
Total loans and leases	4,194,651	3,754,681
Greater than 90 days past due and still accruing	0	0
Commercial real estate | 30 to 59 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	776	6,279
Commercial real estate | 60 to 89 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	857	1,158
Commercial real estate | Greater than 90 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	5,613	12,644
Residential real estate
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	14,991	18,571
Current	1,014,138	902,404
Loans and Leases Receivable, Gross	1,029,129	920,975
Purchased impaired loans, carrying balance	26,820	34,671
Total loans and leases	1,055,949	955,646
Greater than 90 days past due and still accruing	0	0
Residential real estate | 30 to 59 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	8,032	11,060
Residential real estate | 60 to 89 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	1,928	2,976
Residential real estate | Greater than 90 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	5,031	4,535
Home equity
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	6,408	9,051
Current	762,863	804,835
Loans and Leases Receivable, Gross	769,271	813,886
Purchased impaired loans, carrying balance	2,598	3,396
Total loans and leases	771,869	817,282
Greater than 90 days past due and still accruing	0	0
Home equity | 30 to 59 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	2,530	5,245
Home equity | 60 to 89 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	1,083	1,228
Home equity | Greater than 90 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	2,795	2,578
Installment
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	309	602
Current	82,022	92,128
Loans and Leases Receivable, Gross	82,331	92,730
Purchased impaired loans, carrying balance	258	482
Total loans and leases	82,589	93,212
Greater than 90 days past due and still accruing	0	0
Installment | 30 to 59 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	111	420
Installment | 60 to 89 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	50	37
Installment | Greater than 90 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	148	145
Credit card
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	484	700
Current	48,700	45,682
Loans and Leases Receivable, Gross	49,184	46,382
Purchased impaired loans, carrying balance	0	0
Total loans and leases	49,184	46,382
Greater than 90 days past due and still accruing	201	63
Credit card | 30 to 59 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	208	541
Credit card | 60 to 89 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	75	96
Credit card | Greater than 90 days past due
Financing Receivable, Past Due [Line Items]
Financing receivables, Past Due	$ 201	$ 63

LOANS - Restructured Loans (Det

LOANS - Restructured Loans (Details)	12 Months Ended
	Dec. 31, 2019USD ($)loansd	Dec. 31, 2018USD ($)loans	Dec. 31, 2017USD ($)loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extended Maturities	$ 2,877,000	$ 4,093,000	$ 3,261,000
Adjusted Interest Rates	5,284,000	52,000	2,767,000
Combined Rate And Maturity	516,000	0	489,000
Forebearance Agreements	20,320,000	23,175,000	1,181,000
Other	2,473,000	985,000	75,000
Total	$ 31,470,000	$ 28,305,000	$ 7,773,000
Number of Restructured Loans | loans	157	196	214
Restructured loans, Number of Loans | loans	63	43	22
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 31,884,000	$ 28,571,000	$ 7,995,000
Restructured loans, Period End Balance	$ 31,470,000	$ 28,305,000	$ 7,773,000
Restructured loans with payment default within 12 months of modification, Number of Loans | loans	3	1	1
Restructured loans with payment default within 12 months of modification, Period End Balance	$ 7,000,000	$ 41,000	$ 1,500,000
Total restructured loans	30,000,000	38,500,000	23,900,000
Restructured Loans, Accrual Status	11,435,000	16,109,000	17,545,000
Restructured Loans, Nonaccrual Status	18,500,000	22,400,000	6,400,000
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend	2,500,000	0	0
Restructured Loans, Allowance for Loan and Lease Losses Included in Reserves	2,500,000	1,500,000	1,300,000
Accruing TDRs performing in accordance with restructured terms for more than one year	$ 4,700,000	$ 7,900,000	$ 17,200,000
Restructured loans performance threshold (days) | d	90
Commercial & Industrial
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	8	17	7
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 25,009,000	$ 23,943,000	$ 5,724,000
Restructured loans, Period End Balance	$ 25,071,000	$ 23,890,000	$ 5,661,000
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	9	8	8
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 3,024,000	$ 3,385,000	$ 1,816,000
Restructured loans, Period End Balance	$ 2,932,000	$ 3,150,000	$ 1,758,000
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans | loans	30	13	6
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 3,415,000	$ 1,148,000	$ 416,000
Restructured loans, Period End Balance	3,062,000	$ 1,073,000	$ 315,000
Restructured Loans, Loan Relationships, Review Threshold Amount Minimum	$ 250,000
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans | loans	14	5	1
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 395,000	$ 95,000	$ 39,000
Restructured loans, Period End Balance	$ 366,000	$ 192,000	$ 39,000
Installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured loans, Number of Loans | loans	2	0	0
Restructured loans, Restructured loans, Pre-Modification Loan Balance	$ 41,000	$ 0	$ 0
Restructured loans, Period End Balance	$ 39,000	$ 0	$ 0

LOANS - Nonaccrual, Restructure

LOANS - Nonaccrual, Restructured and Impaired Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Troubled Debt Restructuring [Line Items]
Nonaccrual loans	$ 48,165	$ 70,700	$ 24,082
Restructured loans - accrual status	11,435	16,109	17,545
Total impaired loans	59,600	86,809	41,627
Interest income effect
Gross amount of interest that would have been recorded under original terms	5,813	4,656	3,397
Interest included in income
Nonaccrual loans	1,042	715	535
Restructured loans	801	642	710
Impaired Financing Receivable, Interest Income, Accrual Method	1,843	1,357	1,245
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	3,970	3,299	2,152
Loans and Leases Receivable-Nonaccrual, future commitment to lend	3	200	0
Restructured loans - nonaccrual status	18,500	22,400	6,400
Commercial & industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Nonaccrual loans	24,346	30,925	5,229
Total impaired loans	27,480	37,633
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	1,013	404	308
Lease financing
Financing Receivable, Troubled Debt Restructuring [Line Items]
Nonaccrual loans	223	22	82
Total impaired loans	223	22
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	4
Construction real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Nonaccrual loans	0	9	29
Total impaired loans	0	9
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	0	2	1
Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Nonaccrual loans	7,295	20,500	10,616
Total impaired loans	10,831	25,022
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	388	508	603
Residential real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Nonaccrual loans	10,892	13,495	4,140
Total impaired loans	15,162	17,598
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	319	324	222
Home equity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Nonaccrual loans	5,242	5,580	3,743
Total impaired loans	5,700	6,351
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	121	117	103
Installment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Nonaccrual loans	167	169	243
Total impaired loans	204	174
Interest included in income
Impaired Financing Receivable, Interest Income, Accrual Method	$ 2	$ 2	$ 4

LOANS - Investment in Impaired

LOANS - Investment in Impaired Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Current balance	$ 59,600	$ 86,809	$ 41,627
Contractual Principal Balance	84,482	104,732
Allowance for loan and lease losses	2,175	1,160
Average Recorded Investment	79,318	59,728	51,846
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	1,713	1,269
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	130	88
Total interest included in income	1,843	1,357	1,245
Commercial & industrial
Financing Receivable, Impaired [Line Items]
Current balance	27,480	37,633
Contractual Principal Balance	41,222	43,500
Allowance for loan and lease losses	2,044	667
Average Recorded Investment	36,567	15,398	14,371
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	926	360
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	87	44	28
Total interest included in income	1,013	404	308
Lease financing
Financing Receivable, Impaired [Line Items]
Current balance	223	22
Contractual Principal Balance	223	22
Allowance for loan and lease losses	0	0
Average Recorded Investment	225	21	112
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	0	0
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	0	0
Total interest included in income	0	0	4
Construction real estate
Financing Receivable, Impaired [Line Items]
Current balance	0	9
Contractual Principal Balance	0	26
Allowance for loan and lease losses	0	0
Average Recorded Investment	6	20	601
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	0	2
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	0	0
Total interest included in income	0	2	1
Commercial real estate
Financing Receivable, Impaired [Line Items]
Current balance	10,831	25,022
Contractual Principal Balance	18,572	32,884
Allowance for loan and lease losses	113	461
Average Recorded Investment	20,096	26,140	23,569
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	357	490
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	31	18	40
Total interest included in income	388	508	603
Residential real estate
Financing Receivable, Impaired [Line Items]
Current balance	15,162	17,598
Contractual Principal Balance	17,662	20,276
Allowance for loan and lease losses	18	32
Average Recorded Investment	16,361	12,254	8,728
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	307	301
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	12	23	26
Total interest included in income	319	324	222
Home equity
Financing Receivable, Impaired [Line Items]
Current balance	5,700	6,351
Contractual Principal Balance	6,462	7,461
Allowance for loan and lease losses	0	0
Average Recorded Investment	5,893	5,621	4,133
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	121	114
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	3	4
Total interest included in income	121	117	103
Installment
Financing Receivable, Impaired [Line Items]
Current balance	204	174
Contractual Principal Balance	341	563
Allowance for loan and lease losses	0	0
Average Recorded Investment	170	274	332
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	2	2
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	0	0	0
Total interest included in income	2	2	4
Impaired Financing Receivables With Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Current balance	11,719	2,749
Contractual Principal Balance	22,482	2,749
Allowance for loan and lease losses	2,175	1,160
Average Recorded Investment	6,563	3,277	5,051
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method			98
Loans with no related allowance recorded [member]
Financing Receivable, Impaired [Line Items]
Current balance	47,881	84,060
Contractual Principal Balance	62,000	101,983
Allowance for loan and lease losses	0	0
Average Recorded Investment	72,755	56,451	46,795
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			1,147
Loans with no related allowance recorded [member] | Commercial & industrial
Financing Receivable, Impaired [Line Items]
Current balance	16,726	36,694
Contractual Principal Balance	19,709	42,561
Allowance for loan and lease losses	0	0
Average Recorded Investment	31,846	14,498	13,167
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			280
Loans with no related allowance recorded [member] | Lease financing
Financing Receivable, Impaired [Line Items]
Current balance	223	22
Contractual Principal Balance	223	22
Allowance for loan and lease losses	0	0
Average Recorded Investment	168	21	112
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			4
Loans with no related allowance recorded [member] | Construction real estate
Financing Receivable, Impaired [Line Items]
Current balance	0	9
Contractual Principal Balance	0	26
Allowance for loan and lease losses	0	0
Average Recorded Investment	6	20	601
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			1
Loans with no related allowance recorded [member] | Commercial real estate
Financing Receivable, Impaired [Line Items]
Current balance	10,160	23,513
Contractual Principal Balance	17,897	31,375
Allowance for loan and lease losses	0	0
Average Recorded Investment	18,757	24,738	20,935
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			563
Loans with no related allowance recorded [member] | Residential real estate
Financing Receivable, Impaired [Line Items]
Current balance	14,868	17,297
Contractual Principal Balance	17,368	19,975
Allowance for loan and lease losses	0	0
Average Recorded Investment	15,915	11,359	7,616
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			196
Loans with no related allowance recorded [member] | Home equity
Financing Receivable, Impaired [Line Items]
Current balance	5,700	6,351
Contractual Principal Balance	6,462	7,461
Allowance for loan and lease losses	0	0
Average Recorded Investment	5,893	5,541	4,032
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			99
Loans with no related allowance recorded [member] | Installment
Financing Receivable, Impaired [Line Items]
Current balance	204	174
Contractual Principal Balance	341	563
Allowance for loan and lease losses	0	0
Average Recorded Investment	170	274	332
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method			4
Impaired Financing Receivables With Related Allowance [Member] | Commercial & industrial
Financing Receivable, Impaired [Line Items]
Current balance	10,754	939
Contractual Principal Balance	21,513	939
Allowance for loan and lease losses	2,044	667
Average Recorded Investment	4,721	900	1,204
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	57	0	0
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	671	1,509
Contractual Principal Balance	675	1,509
Allowance for loan and lease losses	113	461
Average Recorded Investment	1,339	1,402	2,634
Impaired Financing Receivables With Related Allowance [Member] | Residential real estate
Financing Receivable, Impaired [Line Items]
Current balance	294	301
Contractual Principal Balance	294	301
Allowance for loan and lease losses	18	32
Average Recorded Investment	446	895	1,112
Impaired Financing Receivables With Related Allowance [Member] | Home equity
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	80	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, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of year	$ 1,401	$ 2,781	$ 6,284
Additions	2,448	3,182	4,119
Proceeds from Sale of Other Real Estate	1,453	3,797	6,983
Valuation adjustments	(363)	(765)	(639)
Balance at end of year	2,033	1,401	2,781
Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Additions	415	1,269	1,732
Proceeds from Sale of Other Real Estate	541	2,967	5,409
Valuation adjustments	(112)	(355)	(439)
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Additions	2,033	1,913	2,387
Proceeds from Sale of Other Real Estate	912	830	1,574
Valuation adjustments	$ (251)	$ (410)	$ (200)

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, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for loan and lease losses
Balance at beginning of year	$ 56,542	$ 54,021	$ 57,961
Provision for loan and lease losses	30,598	14,586	3,582
Loans charged off	(35,565)	(20,670)	(13,663)
Recoveries	6,075	8,605	6,141
Total net charge-offs	29,490	12,065	7,522
Balance at end of year	57,650	56,542	54,021
Commercial & Industrial
Allowance for loan and lease losses
Balance at beginning of year	18,746	17,598	19,225
Provision for loan and lease losses	23,631	10,615	6,917
Loans charged off	(26,676)	(11,533)	(10,194)
Recoveries	2,883	2,066	1,650
Total net charge-offs	23,793	9,467	8,544
Balance at end of year	18,584	18,746	17,598
Lease financing
Allowance for loan and lease losses
Balance at beginning of year	1,130	675	716
Provision for loan and lease losses	3	454	(42)
Loans charged off	(162)	0	0
Recoveries	0	1	1
Total net charge-offs	162	(1)	(1)
Balance at end of year	971	1,130	675
Construction real estate
Allowance for loan and lease losses
Balance at beginning of year	3,413	3,577	3,282
Provision for loan and lease losses	(1,100)	(310)	207
Loans charged off	0	0	(1)
Recoveries	68	146	89
Total net charge-offs	(68)	(146)	(88)
Balance at end of year	2,381	3,413	3,577
Commercial real estate
Allowance for loan and lease losses
Balance at beginning of year	21,048	20,930	26,540
Provision for loan and lease losses	5,107	847	(7,291)
Loans charged off	(3,689)	(4,835)	(1,038)
Recoveries	1,113	4,106	2,719
Total net charge-offs	2,576	729	(1,681)
Balance at end of year	23,579	21,048	20,930
Residential
Allowance for loan and lease losses
Balance at beginning of year	4,964	4,683	3,208
Provision for loan and lease losses	739	492	1,695
Loans charged off	(677)	(422)	(435)
Recoveries	273	211	215
Total net charge-offs	404	211	220
Balance at end of year	5,299	4,964	4,683
Home equity
Allowance for loan and lease losses
Balance at beginning of year	5,348	4,935	3,043
Provision for loan and lease losses	695	829	1,778
Loans charged off	(2,591)	(1,725)	(913)
Recoveries	1,335	1,309	1,027
Total net charge-offs	1,256	416	(114)
Balance at end of year	4,787	5,348	4,935
Installment
Allowance for loan and lease losses
Balance at beginning of year	362	307	388
Provision for loan and lease losses	2	(85)	(90)
Loans charged off	(223)	(435)	(225)
Recoveries	251	575	234
Total net charge-offs	(28)	(140)	(9)
Balance at end of year	392	362	307
Credit card
Allowance for loan and lease losses
Balance at beginning of year	1,531	1,316	1,559
Provision for loan and lease losses	1,521	1,744	408
Loans charged off	(1,547)	(1,720)	(857)
Recoveries	152	191	206
Total net charge-offs	1,395	1,529	651
Balance at end of year	$ 1,657	$ 1,531	$ 1,316

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, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Allowance	$ 57,650	$ 56,542	$ 54,021	$ 57,961
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	2,175	1,160
Ending allowance on loans collectively evaluated for impairment	55,475	55,382
Impaired Financing Receivable, Related Allowance	57,650	56,542
Loans and Leases:
Ending balance of loans individually evaluated for impairment	59,600	86,809
Ending balance of loans collectively evaluated for impairment	9,142,065	8,737,405
Loans and Leases Receivable, Net of Deferred Income	9,201,665	8,824,214
Provision for loan and lease losses	30,598	14,586	3,582
Allowance for Loan and Lease Losses, Write-offs	35,565	20,670	13,663
Allowance for Loan and Lease Loss, Recovery of Bad Debts	6,075	8,605	6,141
Commercial & Industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Allowance	18,584	18,746	17,598	19,225
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	2,044	667
Ending allowance on loans collectively evaluated for impairment	16,540	18,079
Impaired Financing Receivable, Related Allowance	18,584	18,746
Loans and Leases:
Ending balance of loans individually evaluated for impairment	27,480	37,633
Ending balance of loans collectively evaluated for impairment	2,438,397	2,477,028
Loans and Leases Receivable, Net of Deferred Income	2,465,877	2,514,661
Provision for loan and lease losses	23,631	10,615	6,917
Allowance for Loan and Lease Losses, Write-offs	26,676	11,533	10,194
Allowance for Loan and Lease Loss, Recovery of Bad Debts	2,883	2,066	1,650
Lease financing
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Allowance	971	1,130	675	716
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0	0
Ending allowance on loans collectively evaluated for impairment	971	1,130
Impaired Financing Receivable, Related Allowance	971	1,130
Loans and Leases:
Ending balance of loans individually evaluated for impairment	223	22
Ending balance of loans collectively evaluated for impairment	88,141	93,393
Loans and Leases Receivable, Net of Deferred Income	88,364	93,415
Provision for loan and lease losses	3	454	(42)
Allowance for Loan and Lease Losses, Write-offs	162	0	0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	0	1	1
Construction real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Allowance	2,381	3,413	3,577	3,282
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0	0
Ending allowance on loans collectively evaluated for impairment	2,381	3,413
Impaired Financing Receivable, Related Allowance	2,381	3,413
Loans and Leases:
Ending balance of loans individually evaluated for impairment	0	9
Ending balance of loans collectively evaluated for impairment	493,182	548,926
Loans and Leases Receivable, Net of Deferred Income	493,182	548,935
Provision for loan and lease losses	(1,100)	(310)	207
Allowance for Loan and Lease Losses, Write-offs	0	0	1
Allowance for Loan and Lease Loss, Recovery of Bad Debts	68	146	89
Commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Allowance	23,579	21,048	20,930	26,540
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	113	461
Ending allowance on loans collectively evaluated for impairment	23,466	20,587
Impaired Financing Receivable, Related Allowance	23,579	21,048
Loans and Leases:
Ending balance of loans individually evaluated for impairment	10,831	25,022
Ending balance of loans collectively evaluated for impairment	4,183,820	3,729,659
Loans and Leases Receivable, Net of Deferred Income	4,194,651	3,754,681
Provision for loan and lease losses	5,107	847	(7,291)
Allowance for Loan and Lease Losses, Write-offs	3,689	4,835	1,038
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1,113	4,106	2,719
Residential real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Allowance	5,299	4,964	4,683	3,208
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	18	32
Ending allowance on loans collectively evaluated for impairment	5,281	4,932
Impaired Financing Receivable, Related Allowance	5,299	4,964
Loans and Leases:
Ending balance of loans individually evaluated for impairment	15,162	17,598
Ending balance of loans collectively evaluated for impairment	1,040,787	938,048
Loans and Leases Receivable, Net of Deferred Income	1,055,949	955,646
Provision for loan and lease losses	739	492	1,695
Allowance for Loan and Lease Losses, Write-offs	677	422	435
Allowance for Loan and Lease Loss, Recovery of Bad Debts	273	211	215
Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Allowance	4,787	5,348	4,935	3,043
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0	0
Ending allowance on loans collectively evaluated for impairment	4,787	5,348
Impaired Financing Receivable, Related Allowance	4,787	5,348
Loans and Leases:
Ending balance of loans individually evaluated for impairment	5,700	6,351
Ending balance of loans collectively evaluated for impairment	766,169	810,931
Loans and Leases Receivable, Net of Deferred Income	771,869	817,282
Provision for loan and lease losses	695	829	1,778
Allowance for Loan and Lease Losses, Write-offs	2,591	1,725	913
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1,335	1,309	1,027
Installment
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0	0
Ending allowance on loans collectively evaluated for impairment	392	362
Impaired Financing Receivable, Related Allowance	392	362
Loans and Leases:
Ending balance of loans individually evaluated for impairment	204	174
Ending balance of loans collectively evaluated for impairment	82,385	93,038
Loans and Leases Receivable, Net of Deferred Income	82,589	93,212
Credit card
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Allowance	1,657	1,531	1,316	$ 1,559
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0	0
Ending allowance on loans collectively evaluated for impairment	1,657	1,531
Impaired Financing Receivable, Related Allowance	1,657	1,531
Loans and Leases:
Ending balance of loans individually evaluated for impairment	0	0
Ending balance of loans collectively evaluated for impairment	49,184	46,382
Loans and Leases Receivable, Net of Deferred Income	49,184	46,382
Provision for loan and lease losses	1,521	1,744	408
Allowance for Loan and Lease Losses, Write-offs	1,547	1,720	857
Allowance for Loan and Lease Loss, Recovery of Bad Debts	$ 152	$ 191	$ 206

PREMISES AND EQUIPMENT - Schedu

PREMISES AND EQUIPMENT - Schedule of Premises and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 328,940	$ 320,902
Less accumulated depreciation and amortization	114,434	105,250
Total premises and equipment	214,506	215,652
Operating Leases, Rent Expense	11,200	9,100	$ 7,100
Land and land improvements [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	54,958	57,701
Buildings [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	163,277	161,817
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	74,881	66,567
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	31,728	29,086
Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 4,096	$ 5,731

LEASES LEASES - Lease Cost (Det

LEASES LEASES - Lease Cost (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating Lease, Cost	$ 7,324
Short-term Lease, Cost	55
Variable Lease, Cost	2,553
Total operating lease cost	$ 9,932

LEASES LEASES - Lease Maturity

LEASES LEASES - Lease Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 7,200
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,166
Lessee, Operating Lease, Liability, Payments, Due Year Three	6,640
Lessee, Operating Lease, Liability, Payments, Due Year Four	6,711
Lessee, Operating Lease, Liability, Payments, Due Year Five	6,457
Lessee, Operating Lease, Liability, Payments, Due after Year Five	50,504
Total lease payments	84,678
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	20,401
Operating Lease, Liability	$ 64,277	$ 65,799	$ 0	$ 0

LEASES LEASES - Schedule of sup

LEASES LEASES - Schedule of supplemental balance sheet information related to leases (Details)	Dec. 31, 2019
Leases [Abstract]
Operating Lease, Weighted Average Remaining Lease Term	15 years 7 months 6 days
Operating Lease, Weighted Average Discount Rate, Percent	3.43%

LEASES LEASES - Supplemental ca

LEASES LEASES - Supplemental cash flow information related to leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Operating Lease, Payments	$ 7,335	$ 0	$ 0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 64,902

LEASES LEASES - Additional Info

LEASES LEASES - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Operating Lease, Right-of-Use Asset	$ 58,600	$ 60,249	$ 0	$ 0
Operating Lease, Liability	$ 64,277	$ 65,799	$ 0	$ 0

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS GOODWILL AND OTHER INTANGIBLE ASSETS-Schedule of Goodwill (Details) - USD ($) $ in Thousands	Aug. 30, 2019	Apr. 01, 2018	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Balance at beginning of year				$ 880,251	$ 204,084	$ 204,084
Goodwill	$ 58,000	$ 675,643	$ 58,000	57,520	676,167	0
Balance at end of year				$ 937,771	$ 880,251	$ 204,084

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLE ASSETS GOODWILL AND OTHER INTANGIBLE ASSETS-Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 100,544	$ 58,120
Finite-Lived Intangible Assets, Accumulated Amortization	24,343	17,315
Core Deposits
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	51,031	54,357
Finite-Lived Intangible Assets, Accumulated Amortization	21,149	16,500
Customer Lists
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	39,420	0
Finite-Lived Intangible Assets, Accumulated Amortization	1,195	0
Other
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	10,093	3,763
Finite-Lived Intangible Assets, Accumulated Amortization	$ 1,999	$ 815

GOODWILL AND OTHER INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLE ASSETS GOODWILL AND OTHER INTANGIBLE ASSETS-Schedule of Future Amortization Expense (Details) $ in Thousands	Dec. 31, 2019USD ($)
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 11,670
Finite-Lived Intangible Assets, Amortization Expense, Year Two	10,263
Finite-Lived Intangible Assets, Amortization Expense, Year Three	7,718
Finite-Lived Intangible Assets, Amortization Expense, Year Four	6,739
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 6,670

GOODWILL AND OTHER INTANGIBLE_6

GOODWILL AND OTHER INTANGIBLE ASSETS GOODWILL AND OTHER INTANGIBLE ASSETS--Additional Information (Details) - USD ($) $ in Thousands	Aug. 30, 2019	Apr. 01, 2018	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 58,000	$ 675,643	$ 58,000	$ 57,520	$ 676,167	$ 0
Intangible assets amortization				$ 9,671	$ 7,359	$ 1,298
Core Deposits
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization method				accelerated basis
Estimated weighted average life (in years)				8 years
Customer Lists
Finite-Lived Intangible Assets [Line Items]
Intangible assets amortization method				straight-line basis
Estimated weighted average life (in years)				11 years
Finite-lived Intangible Assets Acquired	$ 39,400

DEPOSITS DEPOSITS (Details)

DEPOSITS DEPOSITS (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deposits [Abstract]
Time Deposit Maturities, Next Twelve Months	$ 1,752,552
Time Deposit Maturities, Year Two	294,579
Time Deposit Maturities, Year Three	141,261
Time Deposit Maturities, Year Four	37,757
Time Deposit Maturities, Year Five	13,272
Time Deposit Maturities, after Year Five	1,020
Time	$ 2,240,441	$ 2,173,564

DEPOSITS DEPOSITS-Additional In

DEPOSITS DEPOSITS-Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deposits [Abstract]
Time Deposits, at or Above FDIC Insurance Limit	$ 285	$ 284.9

BORROWINGS BORROWINGS - Repurch

BORROWINGS BORROWINGS - Repurchase Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Securities Sold under Agreements to Repurchase		$ 90,181
Carrying Value of Securities Sold under Repurchase Agreements and Deposits Received for Securities Loaned	$ 90,200		$ 85,500
Collateralized Mortgage Obligations
Securities Sold under Agreements to Repurchase		80,426
Mortgage-backed securities
Securities Sold under Agreements to Repurchase		$ 9,755

BORROWINGS - Schedule of Short-

BORROWINGS - Schedule of Short-term Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 30,000
Commitments outstanding to extend credit	0	$ 0
Short-term Debt	$ 1,316,181	$ 1,040,691	$ 814,565
Short-term debt interest rate	1.62%	2.33%	1.32%
Short-term debt, average for the year	$ 1,146,719	$ 947,427	$ 830,365
Short-term debt, average rate (as a percent)	1.90%	1.90%	0.98%
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
Short-term Debt [Line Items]
Short-term Debt	$ 165,181	$ 183,591	$ 72,265
Short-term debt interest rate	0.85%	1.65%	0.19%
Short-term debt, average for the year	$ 155,859	$ 87,221	$ 69,766
Short-term debt, average rate (as a percent)	1.15%	0.58%	0.19%
Short-term debt, maximum month-end balances	$ 260,621	$ 183,591	$ 130,633
Federal Home Loan Bank Borrowings [Member]
Short-term Debt [Line Items]
Short-term Debt	$ 1,151,000	$ 857,100	$ 742,300
Short-term debt interest rate	1.73%	2.48%	1.43%
Short-term debt, average for the year	$ 990,860	$ 857,028	$ 760,558
Short-term debt, average rate (as a percent)	2.37%	2.03%	1.05%
Short-term debt, maximum month-end balances	$ 1,171,400	$ 1,170,800	$ 957,700
Short-term Debt
Short-term Debt [Line Items]
Short-term debt, average for the year	$ 0	$ 3,178	$ 41
Short-term debt, average rate (as a percent)	0.00%	4.36%	4.07%
Short-term debt, maximum month-end balances	$ 0	$ 10,000	$ 0

BORROWINGS - Schedule of Long-t

BORROWINGS - Schedule of Long-term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Amount
FHLB long-term advances	$ 242,428	$ 400,599
Subordinated Debt	170,967	170,550
Unamortized debt issuance costs	(1,007)	(1,185)
Finance Lease, Liability	1,213	0
Other Long-term Debt	775	775
Total long-term debt	$ 414,376	$ 570,739
Average Rate
Federal Home Loan Bank	1.94%	2.08%
Debt, Weighted Average Interest Rate	4.97%	5.28%
Lessee, Finance Lease, Discount Rate	4.48%	0.00%
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	0.00%	0.00%
Long-term Debt, Weighted Average Interest Rate, at Point in Time	3.20%	3.04%
Maturities of Long-term Debt [Abstract]
2020	$ 104,059
2021	19,052
2022	49,451
2023	49
2024	51
Thereafter	$ 241,714

BORROWINGS Borrowings - - Addit

BORROWINGS Borrowings - - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Subordinated Debt	$ 170,967	$ 170,550
Debt, Weighted Average Interest Rate	4.97%	5.28%
Commitments outstanding to extend credit	$ 0	$ 0
Subordinated debt, original issue	$ 120,000
Subordinated Borrowing, Interest Rate	5.13%
Book value of FHLB collateral	$ 6,200,000
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	Dec. 31, 2019USD ($)entity	Dec. 31, 2018USD ($)entity
Derivative [Line Items]
Number of counterparties | entity	18	13
Derivative Asset	$ 112,607	$ 29,189
Derivative Assets (Liabilities), at Fair Value, Net	(9)
Derivative Liability	112,616	29,188
Derivative, Notional Amount	$ 7,586,618	2,719,980
Foreign Exchange [Member]
Derivative [Line Items]
Number of counterparties | entity	6
Credit Risk Contract [Member]
Derivative [Line Items]
Outstanding liability from counterparty contracts	$ 200	100
Derivative, Notional Amount	216,200	138,400
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Derivative, Notional Amount	33,400	20,800
Other Credit Derivatives [Member]
Derivative [Line Items]
Outstanding liability from counterparty contracts		0
Derivative, Notional Amount	37,800	12,300
Credit Risk Derivative Assets, at Fair Value	900
Derivative [Member] | Other Liabilities [Member]
Derivative [Line Items]
Derivative Liability	67,500	4,900
Derivative, Notional Amount	1,900,000	$ 1,400,000
Derivative [Member] | Other Liabilities [Member] | Foreign Exchange [Member]
Derivative [Line Items]
Derivative Liability	18,300
Derivative, Notional Amount	$ 1,900,000

DERIVATIVES - Summary of Deriva

DERIVATIVES - Summary of Derivative Financial Instruments and Balances (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 7,586,618	$ 2,719,980
Derivative Asset	112,607	29,189
Estimate Fair Value Loss	(112,616)	(29,188)
Fair Value Hedges | Matched interest rate swaps | Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,923,375	1,359,990
Derivative Asset	2,636	11,787
Estimate Fair Value Loss	(70,808)	(17,401)
Fair Value Hedges | Matched interest rate swaps | Accrued interest and other assets
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,923,375	1,359,990
Derivative Asset	70,799	17,402
Estimate Fair Value Loss	(2,636)	(11,787)
Foreign Exchange [Member] | Matched interest rate swaps | Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,869,934	0
Derivative Asset	10,433	0
Estimate Fair Value Loss	(28,739)	0
Foreign Exchange [Member] | Matched interest rate swaps | Accrued interest and other assets
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,869,934	0
Derivative Asset	28,739	0
Estimate Fair Value Loss	$ (10,433)	$ 0

DERIVATIVES DERIVATIVES - Discl

DERIVATIVES DERIVATIVES - Disclosure by Type of Financial Instrument (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 112,616	$ 29,189
Derivative Liability, Fair Value, Gross Asset	(188,395)	(14,577)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		14,612
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(75,779)
Fair Value Hedges | Matched interest rate swaps | Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	73,444	29,189
Derivative Liability, Fair Value, Gross Asset	(147,193)	(14,577)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		14,612
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(73,749)
Fair Value Hedges | Foreign Exchange [Member] | Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	39,172	0
Derivative Liability, Fair Value, Gross Asset	(41,202)	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		$ 0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ (2,030)

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, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative, Notional Amount	$ 7,586,618	$ 2,719,980
Average Maturity (years)	3 years 3 months 18 days
Fair Value	$ (9)
Asset conversion swaps | Derivative Financial Instruments Receive Fixed Pay Variable
Derivative [Line Items]
Derivative, Notional Amount	$ 1,923,375
Average Maturity (years)	6 years
Fair Value	$ 68,163
Asset conversion swaps | Derivative Financial Instruments Receive Variable Pay Fixed
Derivative [Line Items]
Derivative, Notional Amount	$ 1,923,375
Average Maturity (years)	6 years
Fair Value	$ (68,172)
Foreign Exchange [Member] | Derivative Financial Instruments Receive Fixed Pay Variable
Derivative [Line Items]
Derivative, Notional Amount	$ 1,869,934
Average Maturity (years)	7 months 6 days
Fair Value	$ 18,306
Foreign Exchange [Member] | Derivative Financial Instruments Receive Variable Pay Fixed
Derivative [Line Items]
Derivative, Notional Amount	$ 1,869,934
Average Maturity (years)	7 months 6 days
Fair Value	$ (18,306)

RELATED PARTIES TRANSACTIONS (D

RELATED PARTIES TRANSACTIONS (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Loans to Related Parties [Roll Forward]
Beginning balance	$ 2,732
Additions	4,348
Deductions	(1,791)
Ending balance	5,289
Loans 90 days past due	$ 0

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Line Items]
Reserves for unfunded commitments	$ 600,000	$ 700,000
Commitments outstanding to extend credit	0	0
Loans and Leases Receivable, Commitments, Fixed Rates	123,700,000	174,000,000
Loans and Leases Receivable, Commitments, Variable Rates	$ 3,200,000,000	$ 2,900,000,000
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	31 years 7 months 6 days	30 years
Letters of credit issued to guarantee performance of a client to a third party	$ 33,400,000	$ 32,700,000
Affordable Housing Program Obligation	38,500,000	39,400,000
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	10,075,000	5,439,000	$ 16,806,000
Amortization Method Qualified Affordable Housing Project Investments, Amortization	6,900,000	5,700,000	4,200,000
Affordable housing contingent commitment	0	0
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	3,100,000	3,900,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	5,100,000	3,900,000
Estimated Litigation Liability	0	0
Commitments to Extend Credit
Commitments and Contingencies Disclosure [Line Items]
Commitments outstanding to extend credit	3,300,000,000	3,000,000,000
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	6,200,000	4,900,000	3,200,000
Historic tax credit [Member]
Commitments and Contingencies Disclosure [Line Items]
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	$ 3,500,000	$ 500,000	$ 13,700,000

INCOME TAXES (Detail)

INCOME TAXES (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current expense [Abstract]
Federal	$ 31,343	$ 34,330	$ 22,599
State	854	1,029	1,265
Total current expense	32,197	35,359	23,864
Deferred (benefit) expense [Abstract]
Federal	10,946	4,675	(4,657)
State	1,644	1,592	169
Total deferred (benefit) expense	12,590	6,267	(4,488)
Income tax expense	44,787	41,626	19,376
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes computed at federal statutory rate on income before income taxes (21% in 2019 and 2018; 35% in 2017)	51,001	44,986	40,657
Benefit from tax-exempt income	(5,964)	(4,499)	(3,427)
Tax credits	(10,075)	(5,439)	(16,806)
Tax rate reduction impact	0	0	(8,191)
Basis reduction on tax credit	738	0	4,599
Tax benefit of equity compensation	(140)	(565)	(1,449)
State income taxes, net of federal tax benefit	1,973	2,070	932
Affordable housing investments	5,825	4,725	2,798
Other	1,429	348	263
Income tax expense	44,787	41,626	19,376
Deferred tax assets [Abstract]
Allowance for loan and lease losses	13,011	12,782
Fair value adjustments on business combinations	6,470	11,199
Deferred compensation	228	392
Postretirement benefits other than pension liability	666	676
Accrued stock-based compensation	1,296	1,145
Other real estate owned write-downs	162	118
Interest on nonaccrual loans	548	1,160
Accrued expenses	4,708	5,808
Net unrealized losses on investment securities and derivatives	0	3,221
State net operating loss	2,792	3,119
Federal tax credit carryforwards	0	873
Other	816	425
Total deferred tax assets	45,503	40,918
Deferred tax asset, Leasing liability	14,806	0
Deferred tax liabilities [Abstract]
Tax depreciation greater than book depreciation	(10,970)	(9,530)
FHLB and FRB stock	(4,043)	(4,044)
Mortgage-servicing rights	(2,435)	(2,285)
Leasing activities	(7,349)	(3,881)
Retirement obligations	8,511	6,614
Intangible assets	(11,647)	(12,310)
Deferred loan fees and costs	(1,100)	(131)
Prepaid expenses	(623)	(582)
Limited partnership investments	2,249	2,367
Unrealized gains on investment securities	(11,359)	0
Foreign exchange deferred income	(2,845)	0
Deferred tax liability, right of use asset	(13,354)	0
Other	(2,048)	(1,867)
Deferred Tax Liabilities, Gross	(78,533)	(43,611)
Total deferred tax liabilities	(33,030)	(2,693)
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Balance at beginning of year	3,735	3,735
Decrease resulting from settlements	(729)	0
Balance at end of year	$ 3,006	$ 3,735	$ 3,735
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	35.00%
Deferred Tax Assets Operating Loss Carryforwards State And Local Acquired	$ 3,600	$ 3,900
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 Unrecognized Deferred Tax Liability, Bad Debt Reserve for Tax Purposes of Qualified Lender		3,400
Unrecognized tax benefits affecting income tax rate	2,400	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, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Pension Cost (Reversal of Cost)	$ 1,041	$ 859	$ (628)
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 Contribution Plan, Cost	$ 0	0	1,900
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	68,286	71,154
Service cost	6,591	6,501	4,894
Interest cost	2,778	2,394	2,325
Actuarial gain (loss)	6,848	(4,032)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	9,459	7,731
Benefit obligation at end of year	75,044	68,286	71,154
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	130,078	144,349
Actual return on plan assets	21,197	(6,540)
Defined Benefit Plan, Plan Assets, Benefits Paid	9,459	7,731
Fair value of plan assets at end of year	141,816	130,078	144,349
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Assets	66,772	61,792
Liabilities	0	0
Net amount recognized	66,772	61,792
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Abstract]
Net actuarial loss	37,278	43,711
Net prior service cost	(1,095)	(1,508)
Deferred tax assets	(8,242)	(9,613)
Net amount recognized	27,941	32,590	19,631	$ 22,803
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	(4,649)	8,180	(3,172)
Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment and Disproportionate Tax Effect Net Of Tax		12,959
Accumulated benefit obligation	74,424	66,320
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	6,591	6,501	4,894
Interest cost	2,778	2,394	2,325
Expected return on plan assets	(9,718)	(9,811)	(9,358)
Amortization of prior service cost	(413)	(413)	(413)
Defined Benefit Plan, Amortization of Gain (Loss)	1,803	2,188	1,924
Net periodic benefit (income) cost	1,041	859	(628)
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	(4,630)	12,319	(2,775)
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	(1,803)	(2,188)	(1,924)
Total recognized in accumulated other comprehensive income	(6,020)	10,544	(4,286)
Total recognized in net periodic benefit cost and accumulated other comprehensive income	(4,979)	11,403	(4,914)
Amortization of loss	2,079	1,867	2,090
Amortization of prior service credit	$ (413)	$ (413)	$ (413)
Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	3.33%	4.31%	3.43%
Rate of compensation increase	3.50%	3.50%	3.50%
Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	4.31%	3.43%	3.88%
Expected return on plan assets	7.25%	7.25%	7.25%
Rate of compensation increase	3.50%	3.50%	3.50%
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2020	$ 5,611
2021	5,210
2022	5,173
2023	5,125
2024	6,070
Thereafter	$ 35,362

EMPLOYEE BENEFIT PLANS Defined

EMPLOYEE BENEFIT PLANS Defined Benefit Plan, Fair Value on Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	$ 141,816	$ 130,078	$ 144,349
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	136,459	122,025
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	5,357	8,053
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	0	0
Fair Value, Inputs, Level 1, 2 and 3 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	141,816	130,078
Cash | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	195	216
Cash | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	0	0
Cash | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	0	0
Cash | Fair Value, Inputs, Level 1, 2 and 3 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	195	216
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	0	0
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	5,357	8,053
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	0	0
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1, 2 and 3 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	5,357	8,053
Fixed income mutual funds | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	75,720	74,453
Fixed income mutual funds | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	0	0
Fixed income mutual funds | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	0	0
Fixed income mutual funds | Fair Value, Inputs, Level 1, 2 and 3 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	75,720	74,453
Equity mutual funds | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	60,544	47,356
Equity mutual funds | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	0	0
Equity mutual funds | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	0	0
Equity mutual funds | Fair Value, Inputs, Level 1, 2 and 3 [Member]
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value measurements	$ 60,544	$ 47,356

REVENUE RECOGNITION REVENUE R_2

REVENUE RECOGNITION REVENUE RECOGNITION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenue Recognition and Deferred Revenue [Abstract]
Interchange income	$ 30.4	$ 31.3
Credit card expense	$ 11.9	$ 11

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Comprehensive Income (Loss), before Reclassification Adjustments and Tax [Abstract]
Unrealized gain (loss) on debt securities	$ 65,858	$ (14,461)	$ 8,447
Unrealized gain (loss) on derivatives	281	628	810
Retirement obligations	4,630	(12,319)	2,775
Total	70,769	(26,152)	12,032
Other Comprehensive Income (Loss) Reclassifications before Tax [Abstract]
Unrealized gain (loss) on debt securities	(370)	(161)	1,649
Unrealized gain (loss) on derivatives	0	0	0
Retirement obligation	1,390	1,775	1,511
Total	(1,760)	(1,936)	138
Transactions Pre-tax
Unrealized gain (loss) on debt securities	66,228	(14,300)	6,798
Unrealized gain (loss) on derivatives	281	628	810
Retirement obligation	6,020	(10,544)	4,286
Total	72,529	(24,216)	11,894
Transactions Tax-effect
Unrealized gain (loss) on debt securities	(14,269)	3,071	(2,431)
Unrealized gain (loss) on derivatives	(64)	(144)	(296)
Retirement obligation	(1,371)	2,364	(1,114)
Total	(15,704)	5,291	(3,841)
Transactions Net of tax
Unrealized gain (loss) on debt securities	51,959	(11,229)	4,367
Unrealized gain (loss) on derivatives	217	484	514
Retirement obligation	4,649	(8,180)	3,172
Total	56,825	(18,925)	8,053
Cumulative effect of accounting change
Unrealized gain (loss) on debt securities	906	(190)
Unrealized gain (loss) on derivatives	0	(124)
Retirement obligation	0	(4,779)
Total	906	(5,093)
Balances Net of tax
Unrealized gain (loss) on debt securities	41,264	(11,601)	(182)	$ (4,549)
Unrealized gain (loss) on derivatives	0	(217)	(577)	(1,091)
Retirement obligation	(27,941)	(32,590)	(19,631)	(22,803)
Total	$ 13,323	$ (44,408)	$ (20,390)	$ (28,443)

ACCUMULATED OTHER COMPREHENSI_4

ACCUMULATED OTHER COMPREHENSIVE INCOME AMOUNT RECLASSIFIED FROM ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Realized gains and losses on securities available for sale	$ (370)	$ (161)	$ 1,649
Amortization of prior service cost	413	413	413
Recognized net actuarial loss	(1,803)	(2,188)	(1,924)
Other Comprehensive Income, Reclassification, Amortization of Defined Benefit Plans items, Pre-tax	(1,390)	(1,775)	(1,511)
Total reclassifications for the period, before tax	$ (1,760)	$ (1,936)	$ 138

CAPITAL - Risk-Based Capital (D

CAPITAL - Risk-Based Capital (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital Conservation Buffer-Fully Phased-In	2.50%
Capital Conservation Buffer-Phased-In Incremental Change	0.625%
Excess Capital	$ 318,300
Risk Based Ratios [Abstract]
Common Equity Tier One Capital	$ 1,245,746	$ 1,215,613
Common Equity Tier One Capital Ratio	11.30%	11.87%
Common Equity Tier One Capital Required for Capital Adequacy	$ 771,666	$ 652,874
Common Equity Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Fully Phased In Basel III	7.00%	7.00%
Common Equity Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets		6.38%
Common Equity Tier One Risk Based Capital Required for Capital Adequacy Fully Phased In Basel III		$ 716,881
Tier One Risk Based Capital [Abstract]
Tier One Risk Based Capital	$ 1,288,185	$ 1,257,366
Tier One Risk Based Capital to Risk Weighted Assets	11.69%	12.28%
Tier One Risk Based Capital Required for Capital Adequacy	$ 937,023	$ 806,491
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	8.50%	7.88%
Tier One Risk Based Capital Required for Capital Adequacy Fully Phased In Basel III		$ 870,499
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Fully Phased In Basel III		8.50%
Capital [Abstract]
Capital	$ 1,475,813	$ 1,444,146
Capital to Risk Weighted Assets	13.39%	14.10%
Capital Required for Capital Adequacy	$ 1,157,498	$ 1,011,314
Capital Required for Capital Adequacy to Risk Weighted Assets	10.50%	9.88%
Capital Required for Capital Adequacy Fully Phased In Basel III		$ 1,075,322
Capital Required for Capital Adequacy to Risk Weighted Assets Fully Phased In Basel III		10.50%
Tier One Leverage Capital [Abstract]
Tier One Leverage Capital	$ 1,288,185	$ 1,257,366
Tier One Leverage Capital to Average Assets	9.58%	9.71%
Tier One Leverage Capital Required for Capital Adequacy	$ 537,606	$ 517,958
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required for Capital Adequacy Fully Phased In Basel III		$ 517,958
Tier One Leverage Capital Required for Capital Adequacy to Average Assets Fully Phased In Basel III		4.00%
Subsidiaries [Member]
Risk Based Ratios [Abstract]
Common Equity Tier One Capital	$ 1,333,978	$ 1,279,492
Common Equity Tier One Capital Ratio	12.11%	12.50%
Common Equity Tier One Capital Required for Capital Adequacy	$ 770,997	$ 652,590
Common Equity Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Fully Phased In Basel III	7.00%	7.00%
Common Equity Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets		6.38%
Common Equity Tier One Risk Based Capital Required to be Well Capitalized To Risk Weighted Assets	$ 715,926	$ 665,386
Common Equity Tier One Risk Based Capital Required to be Well Capitalized To Risk Weighted Assets	6.50%	6.50%
Common Equity Tier One Risk Based Capital Required for Capital Adequacy Fully Phased In Basel III		$ 716,570
Tier One Risk Based Capital [Abstract]
Tier One Risk Based Capital	$ 1,334,082	$ 1,279,596
Tier One Risk Based Capital to Risk Weighted Assets	12.11%	12.50%
Tier One Risk Based Capital Required for Capital Adequacy	$ 936,211	$ 806,141
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	8.50%	7.88%
Capital Required for Capital Adequacy to Risk Weighted Assets	$ 881,140	$ 818,937
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Tier One Risk Based Capital Required for Capital Adequacy Fully Phased In Basel III		$ 870,120
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Fully Phased In Basel III		8.50%
Capital [Abstract]
Capital	$ 1,399,817	$ 1,344,388
Capital to Risk Weighted Assets	12.71%	13.13%
Capital Required for Capital Adequacy	$ 1,156,496	$ 1,010,875
Capital Required for Capital Adequacy to Risk Weighted Assets	10.50%	9.88%
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	$ 1,101,425	$ 1,023,671
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Capital Required for Capital Adequacy Fully Phased In Basel III		$ 1,074,855
Capital Required for Capital Adequacy to Risk Weighted Assets Fully Phased In Basel III		10.50%
Tier One Leverage Capital [Abstract]
Tier One Leverage Capital	$ 1,334,082	$ 1,279,596
Tier One Leverage Capital to Average Assets	9.93%	9.89%
Tier One Leverage Capital Required for Capital Adequacy	$ 537,299	$ 517,710
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	$ 671,623	$ 647,138
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Tier One Leverage Capital Required for Capital Adequacy Fully Phased In Basel III		$ 517,710
Tier One Leverage Capital Required for Capital Adequacy to Average Assets Fully Phased In Basel III		4.00%

CAPITAL - Share Repurchase (Det

CAPITAL - Share Repurchase (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 22, 2019
Capital [Abstract]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased				5,000,000
Treasury Stock, Shares, Acquired	2,753,272	0	0
Treasury Stock Acquired, Average Cost Per Share	$ 24.05
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	2,246,728

STOCK OPTIONS AND AWARDS (Detai

STOCK OPTIONS AND AWARDS (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Noncash Expense	$ 7,969	$ 6,219	$ 5,446
Total unrecognized compensation cost				$ 8,500
Unrecognized compensation cost, period for recognition (in years)	1 year 11 months 4 days
Share-based Compensation Arrangement by Share-based Payment Award, Option Term	10 years
Options outstanding at end of year	37,856	62,410		37,856
Number of Shares Available for Grant				1,513,826
Activity for stock option plan [Roll Forward]
Outstanding at beginning of year (in shares)	62,410
Granted (in shares)	0	0	0
Exercised (in shares)	(24,554)
Forfeited or expired (in shares)	0
Outstanding at end of year (in shares)	37,856	62,410
Exercised (in shares)				37,856
Weighted average exercise price, outstanding at beginning of year (in dollars per share)	$ 9.08
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
Weighted average exercise price, exercised (in dollars per share)	$ 8.37
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)	$ 9.54	$ 9.08
Weighted average exercise price, Exercisable (in dollars per share)				$ 9.54
Weighted average remaining contractual term, outstanding at end of year (in years)	3 years 1 month 13 days
Weighted average remaining contractual life, exercisable at end of year (in years)	3 years 1 month 13 days
Aggregate intrinsic value, outstanding at end of year				$ 602
Aggregate intrinsic value, exercisable at end of year				$ 602
Share-based Payment Arrangement, Additional Disclosure [Abstract]
Total intrinsic value of options exercised	$ 462	$ 734	$ 1,533
Proceeds from exercise of stock options	90	284	341
Share-based Payment Arrangement, Exercise of Option, Tax Benefit	1,844	1,439	1,991
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested in period, total fair value	$ 7,400	$ 5,600	$ 5,600
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	462,446	468,372	648,817
Number of shares granted	395,023	303,930	234,529
Number of shares vested	(295,633)	(267,031)	(307,825)
Number of shares forfeited	(31,267)	(42,825)	(107,149)
Number of shares nonvested at end of year	530,569	462,446	468,372
Weighted average of shares fair value, nonvested at beginning of year	$ 26.39	$ 21.63	$ 17.82
Weighted average of shares fair value granted	26.55	28.94	27.36
Weighted average of shares fair value vested	24.94	20.94	18.12
Weighted average of shares fair value forfeited	28.63	26.38	21.18
Weighted average of shares fair value, nonvested at end of year	$ 27.19	$ 26.39	$ 21.63

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, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator for basic and diluted earnings per share -income available to common shareholders:
Net income	$ 198,075	$ 172,595	$ 96,787
Denominator for basic earnings per share - weighted average shares	98,305,570	88,582,090	61,529,460
Effect of dilutive securities -
Employee stock awards	545,901	514,680	581,329
Warrants	0	517,435	60,801
Denominator for diluted earnings per share - adjusted weighted average shares	98,851,471	89,614,205	62,171,590
Basic	$ 2.01	$ 1.95	$ 1.57
Diluted	$ 2	$ 1.93	$ 1.56

EARNINGS PER COMMON SHARE - Add

EARNINGS PER COMMON SHARE - Additional Information (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share Disclosure [Line Items]
Warrants Exercise Price			$ 12.12
Preferred Stock, Shares Outstanding	0	0	0
Preferred Stock, Shares Authorized	10,000,000	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	0		104,200
MainSource [Member]
Earnings Per Share Disclosure [Line Items]
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, 2019	Dec. 31, 2018
Financial assets
Investment securities held-to-maturity	$ 142,862	$ 429,328
Other investments	125,020	115,660
Deposits
Noninterest-bearing	2,643,928	2,492,434
Savings	2,960,979	3,167,325
Time	2,240,441	2,173,564
Deposits	10,210,229	10,140,394
Carrying value
Financial assets
Cash and short-term investments	257,639	273,959
Investment securities held-to-maturity	142,862	429,328
Other investments	125,020	115,660
Loans held for sale	13,680	4,372
Loans and leases	9,144,015	8,767,672
Interest Receivable	39,591	41,816
Deposits
Deposits	10,210,229	10,140,394
Short-term borrowings	1,316,181	1,040,691
Long-term debt	414,376	570,739
Interest Payable	13,671	12,126
Fair value
Financial assets
Cash and short-term investments	257,639	273,959
Investment securities held-to-maturity	142,821	424,118
Loans held for sale	13,680	4,372
Loans and leases	9,134,215	8,662,868
Interest Receivable	39,591	41,816
Deposits
Deposits	10,209,790	10,113,475
Short-term borrowings	1,316,181	1,040,691
Long-term debt	414,937	557,933
Interest Payable	13,671	12,126
Fair Value, Inputs, Level 1 [Member] | Fair value
Financial assets
Cash and short-term investments	257,639	273,959
Investment securities held-to-maturity	0	0
Loans held for sale	0	0
Loans and leases	0	0
Interest Receivable	0	0
Deposits
Deposits	0	0
Short-term borrowings	1,316,181	1,040,691
Long-term debt	0	0
Interest Payable	1,899	2,035
Fair Value, Inputs, Level 2 [Member] | Fair value
Financial assets
Cash and short-term investments	0	0
Investment securities held-to-maturity	142,821	424,118
Loans held for sale	13,680	4,372
Loans and leases	0	0
Interest Receivable	12,743	13,819
Deposits
Deposits	10,209,790	10,113,475
Short-term borrowings	0	0
Long-term debt	414,937	557,933
Interest Payable	11,772	10,091
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	9,134,215	8,662,868
Interest Receivable	26,848	27,997
Deposits
Deposits	0	0
Short-term borrowings	0	0
Long-term debt	0	0
Interest Payable	$ 0	$ 0

FAIR VALUE DISCLOSURES - Summar

FAIR VALUE DISCLOSURES - Summary of Financial Assets and Liabilities Measure at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Investment securities	$ 2,852,084	$ 2,779,255
Derivatives	112,607	29,189
Liabilities
Derivatives	112,616	29,188
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 [Member]
Assets
Investment securities	100	97
Derivatives		0
Total	100	97
Liabilities
Derivatives		0
Total	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 [Member]
Assets
Investment securities	2,842,794	2,764,443
Derivatives		29,543
Total	2,955,524	2,793,986
Liabilities
Derivatives		29,336
Total	112,922
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 [Member]
Assets
Investment securities	9,190	14,715
Derivatives		0
Total	9,190	14,715
Liabilities
Derivatives		0
Total	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1, 2 and 3 [Member]
Assets
Investment securities	2,852,084	2,779,255
Derivatives		29,543
Total	2,964,814	2,808,798
Liabilities
Derivatives		$ 29,336
Total	112,922
Interest Rate Contract [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 [Member]
Assets
Derivatives	0
Liabilities
Derivatives	0
Interest Rate Contract [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 [Member]
Assets
Derivatives	73,558
Liabilities
Derivatives	73,750
Interest Rate Contract [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 [Member]
Assets
Derivatives	0
Liabilities
Derivatives	0
Interest Rate Contract [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1, 2 and 3 [Member]
Assets
Derivatives	73,558
Liabilities
Derivatives	73,750
Foreign Exchange [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 [Member]
Assets
Derivatives	0
Liabilities
Derivatives	0
Foreign Exchange [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 [Member]
Assets
Derivatives	39,172
Liabilities
Derivatives	39,172
Foreign Exchange [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 [Member]
Assets
Derivatives	0
Liabilities
Derivatives	0
Foreign Exchange [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1, 2 and 3 [Member]
Assets
Derivatives	39,172
Liabilities
Derivatives	$ 39,172

FAIR VALUE DISCLOSURES FAIR VAL

FAIR VALUE DISCLOSURES FAIR VALUE DISCLOSURES - Reconciliation of Gains and Losses on Level 3 Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Fair Value Disclosures [Abstract]
Beginning balance	$ 14,715
Accretion (amortization)	(552)
Increase (decrease) fair value	30
Settlements	(5,003)
Ending balance	$ 9,190

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, 2019	Sep. 30, 2019	Dec. 31, 2018
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	$ 9,268		1,320
Other Real Estate Owned, Fair Value Disclosure		$ 1,088	$ 1,089

BUSINESS COMBINATIONS - Additio

BUSINESS COMBINATIONS - Additional Information - Narrative (Details) - USD ($) $ in Thousands	Aug. 30, 2019	Apr. 01, 2018	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Business Combination, Consideration Transferred		$ 1,059,504
Cash consideration	$ 53,700	43
Stock consideration	60,900	1,043,424
Total assets acquired	74,900	4,402,804
Total liabilities assumed	18,400	4,018,943		$ 18,380	$ 4,018,948	$ 0
Goodwill	58,000	675,643	$ 58,000	57,520	676,167	$ 0
Payments for Merger Related Costs				$ 3,200	$ 37,800
Loans		2,792,572
Business Combination, Acquired Receivables, Gross Contractual Amount		2,900,000
Bannockburn [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 114,600
MainSource [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred		$ 1,100,000
Business Acquisition, Number Of Shares Received by Acquiree		1.3875

BUSINESS COMBINATION BUSINESS C

BUSINESS COMBINATION BUSINESS COMBINATIONS (Details) - USD ($) $ in Thousands	Aug. 30, 2019	Apr. 01, 2018	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Cash consideration	$ 53,700	$ 43
Stock consideration	60,900	1,043,424
Warrant consideration		14,460
Options consideration		1,577
Total purchase consideration		1,059,504
Cash		71,806
Investment securities available-for-sale		900,935
Investment securities held-to-maturity		171,423
Other investments		28,763
Loans		2,792,572
Premises and equipment		98,814
Intangible assets		42,887
Other assets		167,829
Assets held for sale		127,775
Total assets acquired	74,900	4,402,804
Deposits		3,263,920
Subordinated notes		49,027
FHLB advances		291,887
Other borrowings		205,620
Other liabilities		32,649
Liabilities held for sale		175,840
Total liabilities assumed	18,400	4,018,943		$ 18,380	$ 4,018,948	$ 0
Net identifiable assets		383,861
Goodwill	$ 58,000	$ 675,643	$ 58,000	$ 57,520	$ 676,167	$ 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, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Cash	$ 236,221	$ 150,650	$ 150,650	$ 200,691	$ 236,221	$ 150,650	$ 121,598
Other investments				125,020	115,660
Premises and equipment				214,506	215,652
Total assets				14,511,625	13,986,660
Subordinated Debt				170,967	170,550
Other liabilities				323,134	156,587
Total liabilities				12,263,920	11,908,411
Shareholders’ equity				2,247,705	2,078,249	930,664	865,224
Total liabilities and shareholders’ equity				14,511,625	13,986,660
Income Statement [Abstract]
Noninterest income	131,373	103,382	76,142
Interest Expense	123,324	91,147	49,528
Salaries and employee benefits	209,061	188,990	137,240
Professional services	11,254	12,272	15,023
Income before income taxes and equity in undistributed net earnings of subsidiaries	242,862	214,221	116,163
Income tax expense (benefit)	44,787	41,626	19,376
Net income	198,075	172,595	96,787
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	254,900	153,670	104,840
Operating activities
Net income	198,075	172,595	96,787
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	28,138	24,171	12,645
Stock-based compensation expense	7,969	6,219	5,446
Deferred income taxes	12,590	6,267	(4,488)
Decrease (increase) in other assets	(166,477)	34,360	(21,455)
Net cash provided by (used in) operating activities	186,329	261,398	123,524
Investing activities
Net cash acquired (paid) in business combinations	(51,663)		0
Cash Acquired from Acquisition		64,895
Proceeds from sales and maturities of investment securities	557,034	387,351	224,690
Purchases of investment securities	(834,743)	(852,131)	(723,131)
Net cash provided by (used in) investing activities	(252,424)	(205,837)	(429,452)
Financing activities
Net (decrease) increase in short-term borrowings	275,490	30,531	6,653
Cash dividends paid on common stock	(89,097)	(79,655)	(41,178)
Treasury stock purchase	(66,218)	0	0
Proceeds from exercise of stock options, net of shares purchased	90	284	341
Net cash provided by (used in) financing activities	30,565	30,010	334,980
Net increase (decrease) in cash	(35,530)	85,571	29,052
Cash and due from banks at beginning of year	236,221	150,650	121,598
Cash and due from banks at end of year	200,691	236,221	150,650
Parent Company [Member]
Statement of Financial Position [Abstract]
Cash	86,878	86,878	59,285	55,869	86,878	$ 57,719	$ 59,285
Other investments				1,116	694
Subordinated notes from subsidiaries				7,500	7,500
Premises and equipment				1,344	1,361
Other assets				77,572	71,817
Total assets				2,424,652	2,254,099
Subordinated Debt				171,983	171,416
Dividends payable				849	465
Other liabilities				4,115	3,969
Total liabilities				176,947	175,850
Shareholders’ equity				2,247,705	2,078,249
Total liabilities and shareholders’ equity				2,424,652	2,254,099
Income Statement [Abstract]
Interest income	30	23	6
Noninterest income	191	0	86
Dividends from subsidiaries	196,800	107,340	54,600
Total income	197,021	107,363	54,692
Interest Expense	9,552	8,798	6,152
Salaries and employee benefits	8,169	6,413	5,519
Professional services	1,040	5,130	970
Other	6,599	5,648	4,819
Total expenses	25,360	25,989	17,460
Income before income taxes and equity in undistributed net earnings of subsidiaries	171,661	81,374	37,232
Income tax expense (benefit)	(5,975)	(6,687)	(7,080)
Equity in undistributed earnings (loss) of subsidiaries	(20,439)	(84,534)	(52,475)
Net income	198,075	172,595	96,787
Operating activities
Net income	198,075	172,595	96,787
Adjustments to reconcile net income to net cash provided by operating activities
Equity in undistributed earnings (loss) of subsidiaries	(20,439)	(84,534)	(52,475)
Depreciation and amortization	584	194	193
Stock-based compensation expense	7,969	6,219	5,446
Deferred income taxes	1,255	739	(360)
(Decrease) increase in dividends payable	384	(10,500)	579
Increase (decrease) in other liabilities	(244)	9,979	(889)
Decrease (increase) in other assets	(7,187)	16,346	(6,951)
Net cash provided by (used in) operating activities	180,397	111,038	42,330
Investing activities
Capital contributions to subsidiaries	0	(3,000)	0
Net cash acquired (paid) in business combinations	(53,660)		0
Cash Acquired from Acquisition		11,353
Proceeds from sales and maturities of investment securities	264	0	0
Purchases of investment securities	(500)	0	0
Net cash provided by (used in) investing activities	(53,896)	8,353	0
Financing activities
Net (decrease) increase in short-term borrowings	0	(8,333)	0
Cash dividends paid on common stock	(89,097)	(79,655)	(41,178)
Treasury stock purchase	(66,218)	0	0
Proceeds from exercise of stock options, net of shares purchased	90	284	341
Other	(2,285)	(2,528)	(3,059)
Net cash provided by (used in) financing activities	(157,510)	(90,232)	(43,896)
Net increase (decrease) in cash	(31,009)	29,159	(1,566)
Cash and due from banks at beginning of year	86,878	57,719	59,285
Cash and due from banks at end of year	$ 55,869	$ 86,878	$ 57,719
Commercial Banks [Member] | Parent Company [Member]
Statement of Financial Position [Abstract]
Investment in subsidiaries				2,272,991	2,078,655
Nonbanks [Member] | Parent Company [Member]
Statement of Financial Position [Abstract]
Investment in subsidiaries				8,260	7,194
Subsidiaries [Member] | Parent Company [Member]
Statement of Financial Position [Abstract]
Investment in subsidiaries				$ 2,281,251	$ 2,085,849