Community Bank System (CBU) 10-Q 10 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	COMMUNITY BANK SYSTEM, INC.
Entity Central Index Key	0000723188
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		51,529,044
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1

CONSOLIDATED STATEMENTS OF COND

CONSOLIDATED STATEMENTS OF CONDITION (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets:
Cash and cash equivalents	$ 508,364	$ 211,834
Available-for-sale investment securities (cost of $2,915,267 and $2,952,278, respectively)	2,922,943	2,936,049
Equity and other securities (cost of $42,241 and $44,678, respectively)	43,204	45,609
Loans held for sale, at fair value	212	83
Loans	6,266,086	6,281,121
Allowance for loan losses	(49,107)	(49,284)
Net loans	6,216,979	6,231,837
Goodwill, net	733,503	733,503
Core deposit intangibles, net	17,113	18,596
Other intangibles, net	53,803	55,250
Intangible assets, net	804,419	807,349
Premises and equipment, net	151,976	119,988
Accrued interest and fees receivable	35,573	31,048
Other assets	232,797	223,498
Total assets	10,916,467	10,607,295
Liabilities:
Noninterest-bearing deposits	2,346,635	2,312,816
Interest-bearing deposits	6,273,027	6,009,555
Total deposits	8,619,662	8,322,371
Short-term borrowings	0	54,400
Securities sold under agreement to repurchase, short-term	249,880	259,367
Other long-term debt	1,953	1,976
Subordinated debt held by unconsolidated subsidiary trusts	97,939	97,939
Accrued interest and other liabilities	189,905	157,459
Total liabilities	9,159,339	8,893,512
Commitments and contingencies (See Note K)
Shareholders' equity:
Preferred stock, $1.00 par value, 500,000 shares authorized, 0 shares issued	0	0
Common stock, $1.00 par value, 75,000,000 shares authorized; 51,727,758 and 51,576,839 shares issued, respectively	51,728	51,577
Additional paid-in capital	913,917	911,748
Retained earnings	817,933	795,563
Accumulated other comprehensive (loss)	(26,762)	(45,305)
Treasury stock, at cost (256,387 shares, including 176,252 shares held by deferred compensation arrangements at March 31, 2019 and 319,015 shares including 207,403 shares held by deferred compensation arrangements at December 31, 2018, respectively)	(9,601)	(11,528)
Deferred compensation arrangements (176,252 and 207,403 shares, respectively)	9,913	11,728
Total shareholders' equity	1,757,128	1,713,783
Total liabilities and shareholders' equity	$ 10,916,467	$ 10,607,295

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF CONDITION (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets:
Available-for-sale investment securities, cost	$ 2,915,267	$ 2,952,278
Equity and other securities, cost	$ 42,241	$ 44,678
Shareholders' equity:
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	500,000	500,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	75,000,000	75,000,000
Common stock, shares issued (in shares)	51,727,758	51,576,839
Treasury stock, shares at cost (in shares)	256,387	319,015
Shares held by deferred compensation arrangements (in shares)	176,252	207,403

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Interest income:
Interest and fees on loans	$ 73,703	$ 69,441
Interest and dividends on taxable investments	16,087	15,525
Interest on nontaxable investments	2,891	3,438
Total interest income	92,681	88,404
Interest expense:
Interest on deposits	4,107	2,132
Interest on borrowings	621	480
Interest on subordinated debt held by unconsolidated subsidiary trusts	1,094	1,168
Total interest expense	5,822	3,780
Net interest income	86,859	84,624
Provision for loan losses	2,422	3,679
Net interest income after provision for loan losses	84,437	80,945
Noninterest revenues:
Deposit service fees	15,864	19,177
Other banking revenues	1,536	1,243
Employee benefit services	24,054	23,006
Insurance services	7,862	7,359
Wealth management services	6,349	6,706
Unrealized gain on equity securities	31	0
Total noninterest revenues	55,696	57,491
Noninterest expenses:
Salaries and employee benefits	53,379	51,859
Occupancy and equipment	10,288	10,531
Data processing and communications	9,399	8,742
Amortization of intangible assets	4,130	4,798
Legal and professional fees	2,720	2,781
Business development and marketing	2,788	2,059
Acquisition expenses	534	(8)
Other expenses	5,414	5,569
Total noninterest expenses	88,652	86,331
Income before income taxes	51,481	52,105
Income taxes	9,535	11,999
Net income	$ 41,946	$ 40,106
Basic earnings per share (in dollars per share)	$ 0.81	$ 0.78
Diluted earnings per share (in dollars per share)	$ 0.80	$ 0.78

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Pension and other post-retirement obligations:
Amortization of actuarial losses included in net periodic pension cost, gross	$ 651	$ 303
Tax effect	(159)	(74)
Amortization of actuarial losses included in net periodic pension cost, net	492	229
Amortization of prior service cost included in net periodic pension cost, gross	(29)	(127)
Tax effect	7	31
Amortization of prior service cost included in net periodic pension cost, net	(22)	(96)
Other comprehensive income related to pension and other post-retirement obligations, net of taxes	470	133
Unrealized gains (losses) on available-for-sale securities:
Net unrealized holding gains (losses) arising during period, gross	23,905	(41,815)
Tax effect	(5,832)	10,155
Net unrealized holding gains (losses) arising during period, net	18,073	(31,660)
Other comprehensive income/(loss) related to unrealized gains (losses) on available-for-sale securities, net of taxes	18,073	(31,660)
Other comprehensive income (loss), net of tax	18,543	(31,527)
Net income	41,946	40,106
Comprehensive income	60,489	$ 8,579
Accumulated Other Comprehensive Income By Component:
Unrealized (loss) for pension and other post-retirement obligations	(42,875)		$ (43,497)
Tax effect	10,508		10,660
Net unrealized (loss) for pension and other post-retirement obligations	(32,367)		(32,837)
Unrealized gain (loss) on available-for-sale securities	7,676		(16,229)
Tax effect	(2,071)		3,969
Reclassification of other comprehensive income due to change in accounting principle - equity securities	0		(208)
Net unrealized gain (loss) on available-for-sale securities	5,605		(12,468)
Accumulated other comprehensive (loss)	$ (26,762)		$ (45,305)

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Common Stock Outstanding [Member]	Common Stock Amount Issued [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) [Member]	Treasury Stock [Member]	Deferred Compensation Arrangements [Member]	Total
Balance at Dec. 31, 2017		$ 51,264	$ 894,879	$ 700,557	$ (3,699)	$ (21,014)	$ 13,328	$ 1,635,315
Balance (in shares) at Dec. 31, 2017	50,696,077
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income				40,106				40,106
Other comprehensive income (loss), net of tax					(31,527)			(31,527)
Dividends declared:
Common				(17,259)				(17,259)
Common stock activity under employee stock ownership plan		110	460					570
Common stock activity under employee stock ownership plan (in shares)	110,413
Stock-based compensation			1,715					1,715
Distribution of stock under deferred compensation arrangements						1,898	(1,898)	0
Distribution of stock under deferred compensation arrangements (in shares)	35,233
Treasury stock issued to benefit plans, net			982			1,483	81	2,546
Treasury stock issued to benefit plans, net (in shares)	41,880
Balance at Mar. 31, 2018		51,374	898,036	723,404	(35,226)	(17,633)	11,511	1,631,466
Balance (in shares) at Mar. 31, 2018	50,883,603
Balance at Dec. 31, 2018		51,577	911,748	795,563	(45,305)	(11,528)	11,728	1,713,783
Balance (in shares) at Dec. 31, 2018	51,257,824
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income				41,946				41,946
Other comprehensive income (loss), net of tax					18,543			18,543
Dividends declared:
Common				(19,576)				(19,576)
Common stock activity under employee stock ownership plan		151	(995)					(844)
Common stock activity under employee stock ownership plan (in shares)	150,919
Stock-based compensation			1,391					1,391
Distribution of stock under deferred compensation arrangements			1,064			830	(1,894)	0
Distribution of stock under deferred compensation arrangements (in shares)	32,431
Treasury stock issued to benefit plans, net			709			1,097	79	1,885
Treasury stock issued to benefit plans, net (in shares)	30,197
Balance at Mar. 31, 2019		$ 51,728	$ 913,917	$ 817,933	$ (26,762)	$ (9,601)	$ 9,913	$ 1,757,128
Balance (in shares) at Mar. 31, 2019	51,471,371

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Dividends declared:
Dividends declared per common share (in dollars per share)	$ 0.38	$ 0.34

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities:
Net income	$ 41,946	$ 40,106
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	3,830	4,001
Amortization of intangible assets	4,130	4,798
Net accretion on securities, loans and borrowings	(1,944)	(2,214)
Stock-based compensation	1,391	1,715
Provision for loan losses	2,422	3,679
Amortization of mortgage servicing rights	98	117
Unrealized gain on equity securities	(31)	0
Income from bank-owned life insurance policies	(391)	(388)
Net loss (gain) on sale of loans and other assets	22	(80)
Change in other assets and other liabilities	(16,864)	9,253
Net cash provided by operating activities	34,609	60,987
Investing activities:
Proceeds from maturities, calls, and paydowns of available-for-sale investment securities	52,520	27,363
Proceeds from maturities and redemptions of equity and other investment securities	2,460	4,960
Purchases of available-for-sale investment securities	(13,388)	(23,434)
Purchases of equity and other securities	(24)	(21)
Net decrease in loans	11,847	25,900
Cash paid for acquisitions, net of cash acquired of $0 and $16, respectively	(1,200)	(1,464)
Purchases of premises and equipment, net	(1,227)	(1,556)
Real estate limited partnership investments	(564)	(79)
Net cash provided by investing activities	50,424	31,669
Financing activities:
Net increase in deposits	297,291	326,672
Net decrease in borrowings	(63,910)	(81,338)
Issuance of common stock	(844)	570
Purchases of treasury stock	(79)	(81)
Sales of treasury stock	1,885	2,546
Increase in deferred compensation arrangements	79	81
Cash dividends paid	(19,806)	(17,281)
Withholding taxes paid on share-based compensation	(3,119)	(964)
Net cash provided by financing activities	211,497	230,205
Change in cash and cash equivalents	296,530	322,861
Cash and cash equivalents at beginning of period	211,834	221,038
Cash and cash equivalents at end of period	508,364	543,899
Supplemental disclosures of cash flow information:
Cash paid for interest	5,684	3,757
Cash paid for income taxes	4,486	564
Supplemental disclosures of noncash financing and investing activities:
Dividends declared and unpaid	19,578	17,438
Transfers from loans to other real estate	412	942
Acquisitions:
Common stock issued	0	0
Fair value of assets acquired, excluding acquired cash and intangibles	0	27
Fair value of liabilities assumed	$ 0	$ 31

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Investing activities:
Cash acquired from acquisition	$ 0	$ 16

BASIS OF PRESENTATION

BASIS OF PRESENTATION	3 Months Ended
	Mar. 31, 2019
BASIS OF PRESENTATION [Abstract]
BASIS OF PRESENTATION	NOTE A: BASIS OF PRESENTATION The interim financial data as of and for the three months ended March 31, 2019 is unaudited; however, in the opinion of Community Bank System, Inc. (the “Company”), the interim data includes all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the results for the interim periods in conformity with generally accepted accounting principles in the United States of America (“GAAP”). The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period.

ACQUISITIONS

ACQUISITIONS	3 Months Ended
	Mar. 31, 2019
ACQUISITIONS [Abstract]
ACQUISITIONS	NOTE B: ACQUISITIONS Pending Acquisition – Kinderhook Bank Corp. On January 22, 2019, the Company announced that it had entered into a definitive agreement to acquire Kinderhook Bank Corp. (“Kinderhook”), parent company of The National Union Bank of Kinderhook headquartered in Kinderhook, New York, for approximately $93.4 million in cash. The acquisition will extend the Company’s footprint into the Capital District of Upstate New York. Upon completion of the merger, the Bank will add 11 branch locations across a five county area in the Capital District of Upstate New York. The parties have received the shareholder and regulatory approvals necessary to complete the merger, including approval from the Office of the Comptroller of the Currency and a waiver from filing an application with the Federal Reserve Bank of New York. The Company expects the merger to close on July 12, 2019, subject to customary closing conditions. The Company expects to incur certain one-time, transaction-related costs in 2019. On January 2, 2019, the Company, through its subsidiary, Community Investment Services, Inc. (“CISI”), completed its acquisition of certain assets of Wealth Resources Network, Inc. (“Wealth Resources”), a financial services business headquartered in Liverpool, New York. The Company paid $1.2 million in cash to acquire a customer list from Wealth Resources, and recorded a $1.2 million customer list intangible asset in conjunction with the acquisition. The effects of the acquired assets have been included in the consolidated financial statements since that date. On April 2, 2018, the Company, through its subsidiary, Benefit Plans Administrative Services, Inc. (“BPAS”), acquired certain assets of HR Consultants (SA), LLC (“HR Consultants”), a provider of actuarial and benefit consulting services headquartered in Puerto Rico. The Company paid $0.3 million in cash to acquire the assets of HR Consultants and recorded intangible assets of $0.3 million in conjunction with the acquisition. The effects of the acquired assets have been included in the consolidated financial statements since that date. On January 2, 2018, the Company, through its subsidiary, OneGroup NY, Inc. (“OneGroup”), completed its acquisition of certain assets of Penna & Associates Agency, Inc. (“Penna”), an insurance agency headquartered in Johnson City, New York. The Company paid $0.8 million in cash to acquire the assets of Penna, and recorded goodwill in the amount of $0.3 million and a customer list intangible asset of $0.3 million in conjunction with the acquisition. The effects of the acquired assets and liabilities have been included in the consolidated financial statements since that date. On January 2, 2018, the Company, through its subsidiary, CISI, completed its acquisition of certain assets of Styles Bridges Associates (“Styles Bridges”), a financial services business headquartered in Canton, New York. The Company paid $0.7 million in cash to acquire a customer list from Styles Bridges, and recorded a $0.7 million customer list intangible asset in conjunction with the acquisition. The effects of the acquired assets have been included in the consolidated financial statements since that date. The assets and liabilities assumed in the acquisitions were recorded at their estimated fair values based on management's best estimates using information available at the dates of the acquisitions, and were subject to adjustment based on updated information not available at the time of the acquisitions. The following table summarizes the estimated fair value of the assets acquired and liabilities assumed after considering the measurement period adjustments described above: 2019 2018 (000s omitted) Wealth Resources Other (1) Consideration paid : Cash $ 1,200 $ 1,753 Total net consideration paid $ 1,200 $ 1,753 Recognized amounts of identifiable assets acquired and liabilities assumed: Cash and cash equivalents 0 16 Premises and equipment 0 10 Other assets 0 105 Other intangibles 1,200 1,343 Other liabilities 0 (31 ) Total identifiable assets, net 1,200 1,443 Goodwill $ 0 $ 310 (1) The other intangibles related to the Wealth Resources, Styles Bridges, Penna, and HR Consultants acquisitions are being amortized using an accelerated method over their estimated useful life of eight years. The goodwill, which is not amortized for book purposes, was assigned to the All Other segment for the Penna acquisition. Goodwill arising from the Penna acquisition is deductible for tax purposes. Direct costs related to the acquisitions were expensed as incurred. Merger and acquisition integration-related expenses amount to $0.5 million during the three months ended March 31, 2019 and have been separately stated in the consolidated statements of income. Merger and acquisition integration-related expenses for the three months ended March 31, 2018 were immaterial.

ACCOUNTING POLICIES

ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2019
ACCOUNTING POLICIES [Abstract]
ACCOUNTING POLICIES	NOTE C: ACCOUNTING POLICIES The accounting policies of the Company, as applied in the consolidated interim financial statements presented herein, are substantially the same as those followed on an annual basis as presented on pages 65 through 75 of the Annual Report on Form 10-K for the year ended December 31, 2018 filed with the Securities and Exchange Commission (“SEC”) on March 1, 2019 except as noted below. Contract Balances A contract asset balance occurs when an entity performs a service for a customer before the customer pays consideration (resulting in a contract receivable) or before payment is due (resulting in a contract asset). A contract liability balance is an entity’s obligation to transfer a service to a customer for which the entity has already received payment (or payment is due) from the customer. The Company’s noninterest revenue streams are largely based on transactional activity, or standard month-end revenue accruals such as asset management fees based on month-end market values. Consideration is often received immediately or shortly after the Company satisfies its performance obligation and revenue is recognized. The Company does not typically enter into long-term revenue contracts with customers, and therefore, does not experience significant contract balances. As of March 31, 2019, $29.4 million of accounts receivable, including $9.5 million of unbilled fee revenue, and $3.5 million of unearned revenue was recorded in the consolidated statements of condition. As of December 31, 2018, $26.4 million of accounts receivable, including $7.8 million of unbilled fee revenue, and $2.2 million of unearned revenue was recorded in the consolidated statements of condition. Leases The Company occupies certain offices and uses certain equipment under non-cancelable operating lease agreements. The Company determines if an arrangement is a lease at inception. The right-of-use assets associated with operating leases are recorded in premises and equipment in the Company’s consolidated statements of condition. The lease liabilities associated with operating leases are included in accrued interest and other liabilities in the Company’s consolidated statements of condition. Right-of-use assets represent the Company’s right to use the underlying assets for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the associated leases. Operating lease right-of-use assets and liabilities are recognized at the commencement date of the lease based on the present value of lease payments over the lease term. The Company uses interest rates on advances from the Federal Home Loan Bank of New York available at the time of commencement to determine the present value of lease payments. The operating lease right-of-use assets include any lease payments made at the time of commencement and exclude lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Lease expense is recognized on a straight-line basis over the lease term and is included in occupancy and equipment expense in the Company’s consolidated statements of income. The Company elected to account for lease and non-lease components separately, applies a portfolio approach to account for the lease right-of-use assets and liabilities for certain equipment leases and elected to exclude leases with a term of 12 months or less from the recognition and measurement policies described above. Derivative Financial Instruments and Hedging Activities The Company accounts for derivative financial instruments at fair value. If certain conditions are met, a derivative may be specifically designated as (1) a hedge of the exposure to changes in the fair value of a recognized asset or liability or an unrecognized firm commitment (“fair value hedge”), (2) a hedge of the exposure to variable cash flows of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (“cash flow hedge”), or (3) an instrument with no hedging designation (“stand-alone derivative”). For a fair value hedge, the gain or loss on the derivative, as well as the offsetting loss or gain on the hedged item, are recognized in current earnings as fair values change. For a cash flow hedge, the gain or loss on the derivative is reported in other comprehensive income and is reclassified into earnings in the same periods during which the hedged transaction affects earnings. Changes in the fair value of derivatives that do not qualify for hedge accounting are reported currently in earnings, as noninterest revenues. Net cash settlements on derivatives that qualify for hedge accounting are recorded in interest income or interest expense, based on the item being hedged. Net cash settlements on derivatives that do not qualify for hedge accounting are reported in noninterest revenues. Cash flows on hedges are classified in the consolidated statement of cash flow statement the same as the cash flows of the items being hedged. The Company formally documents the relationship between derivatives and hedged items, as well as the risk-management objective and strategy for undertaking hedge transactions at the inception of the hedging relationship. This documentation includes linking the fair value or cash flow hedges to specific assets and liabilities on the statement of condition or to specific commitments or forecasted transactions. The Company also formally assesses, both at the hedge’s inception and on an ongoing basis, whether the derivative instruments that are used are highly effective in offsetting changes in fair values or cash flows of the hedged items. When hedge accounting is discontinued, subsequent changes in fair value of the derivative are recorded in noninterest revenues. When a fair value hedge is discontinued, the hedged asset or liability is no longer adjusted for changes in fair value and the existing basis adjustment is amortized or accreted over the remaining life of the asset or liability. When a cash flow hedge is discontinued, but the hedged cash flows or forecasted transactions are still expected to occur, gains or losses that were accumulated in other comprehensive income are amortized into earnings over the same periods which the hedged transactions will affect earnings. Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) Topic 840, Leases In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. New Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326) In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350)

INVESTMENT SECURITIES

INVESTMENT SECURITIES	3 Months Ended
	Mar. 31, 2019
INVESTMENT SECURITIES [Abstract]
INVESTMENT SECURITIES	NOTE D: INVESTMENT SECURITIES The amortized cost and estimated fair value of investment securities as of March 31, 2019 and December 31, 2018 are as follows: March 31, 2019 December 31, 2018 (000's omitted) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-Sale Portfolio: U.S. Treasury and agency securities $ 2,033,399 $ 6 , $ 5 , $ 2,034,972 $ 2,036 , $ 2 , $ 14,911 $ 2,023 , Obligations of state and political subdivisions 423 , 9,319 76 433 , 453 , 6 , 1,049 459 , Government agency mortgage-backed securities 389 , 2,587 5 , 386 , 390 , 1 , 9 , 382 , Corporate debt securities 2,572 0 19 2,553 2,588 0 42 2 , Government agency collateralized mortgage obligations 66 , 88 598 65 , 69 , 60 1,283 68 , Total available-for-sale portfolio $ 2 , , $ 18 , $ 11 , $ 2,922,943 $ 2 , , $ 10 , $ 26 , $ 2 , , Equity and other Securities: Equity securities, at fair value $ 251 $ 215 $ 2 $ 464 $ 251 $ 200 $ 19 $ 432 Federal Home Loan Bank common stock 6,308 0 0 6,308 8,768 0 0 8,768 Federal Reserve Bank common stock 30,690 0 0 30,690 30,690 0 0 30,690 Other equity securities, at adjusted cost 4 , 750 0 5,742 4 , 750 0 5,719 Total equity and other securities $ 42,241 $ 965 $ 2 $ 43,204 $ 44 , $ 950 $ 19 $ 45 , A summary of investment securities that have been in a continuous unrealized loss position is as follows: As of March 31, 2019 Less than 12 Months 12 Months or Longer Total (000's omitted) # Fair Value Gross Unrealized Losses # Fair Value Gross Unrealized Losses # Fair Value Gross Unrealized Losses Available-for-Sale Portfolio: U.S. Treasury and agency securities 0 $ 0 $ 0 48 $ 862,482 $ 5,268 48 $ 862 , $ 5 , Obligations of state and political subdivisions 3 869 2 20 11,854 74 23 12 , 76 Government agency mortgage-backed securities 9 5 , 6 181 242 , 5 , 190 247 , 5 , Corporate debt securities 0 0 0 1 2,553 19 1 2,553 19 Government agency collateralized mortgage obligations 1 1 0 39 56,690 598 40 56 , 598 Total available-for-sale investment portfolio 13 $ 6,111 $ 8 289 $ 1,176 , $ 11 , 302 $ 1,182 , $ 11 , Equity and other Securities: Equity securities, at fair value 1 $ 98 $ 2 0 $ 0 $ 0 1 $ 98 $ 2 Total equity and other securities 1 $ 98 $ 2 0 $ 0 $ 0 1 $ 98 $ 2 As of December 31, 2018 Less than 12 Months 12 Months or Longer Total (000's omitted) # Fair Value Gross Unrealized Losses # Fair Value Gross Unrealized Losses # Fair Value Gross Unrealized Losses Available-for-Sale Portfolio: U.S. Treasury and agency securities 7 $ 473 , $ 682 64 $ 1,213,276 $ 14,229 71 $ 1,686 , $ 14,911 Obligations of state and political subdivisions 118 55 , 216 97 51,753 833 215 107 , 1,049 Government agency mortgage-backed securities 43 47,708 258 181 253 , 9 , 224 301 , 9 , Corporate debt securities 0 0 0 1 2,546 42 1 2,546 42 Government agency collateralized mortgage obligations 1 66 0 41 63,112 1,283 42 63 , 1,283 Total available-for-sale investment portfolio 169 $ 576 , $ 1 , 384 $ 1,584,618 $ 25 , 553 $ 2 , , $ 26 , Equity and other Securities: Equity securities, at fair value 1 $ 82 $ 19 0 $ 0 $ 0 1 $ 82 $ 19 Total equity and other securities 1 $ 82 $ 19 0 $ 0 $ 0 1 $ 82 $ 19 The unrealized losses reported pertaining to securities issued by the U.S. government and its sponsored entities, include treasuries, agencies, and mortgage-backed securities issued by Ginnie Mae, Fannie Mae, and Freddie Mac, which are currently rated AAA by Moody’s Investor Services, AA+ by Standard & Poor’s and are guaranteed by the U.S. government. The majority of the obligations of state and political subdivisions and corporations carry a credit rating of A or better. Additionally, a majority of the obligations of state and political subdivisions carry a secondary level of credit enhancement. The Company does not intend to sell these securities, nor is it more likely than not that the Company will be required to sell these securities prior to recovery of the amortized cost. The unrealized losses in the portfolios are primarily attributable to changes in interest rates. As such, management does not believe any individual unrealized loss as of March 31, 2019 represents other-than-temporary impairment. The amortized cost and estimated fair value of debt securities at March 31, 2019, by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Securities not due at a single maturity date are shown separately. Available-for-Sale (000's omitted) Amortized Cost Fair Value Due in one year or less $ 76,873 $ 76,767 Due after one through five years 2,093,361 2,096,910 Due after five years through ten years 152,168 156,042 Due after ten years 137,485 140,965 Subtotal 2,459,887 2,470,684 Government agency mortgage-backed securities 389,154 386,543 Government agency collateralized mortgage obligations 66,226 65,716 Total $ 2,915,267 $ 2,922,943 As of March 31, 2019, $263.0 million of U.S. Treasury securities were pledged as collateral for securities sold under agreement to repurchase. All securities sold under agreement to repurchase as of March 31, 2019 have an overnight and continuous maturity.

LOANS

LOANS	3 Months Ended
	Mar. 31, 2019
LOANS [Abstract]
LOANS	NOTE E: LOANS The segments of the Company’s loan portfolio are disaggregated into the following classes that allow management to monitor risk and performance: • Consumer mortgages consist primarily of fixed rate residential instruments, typically 10 – 30 years in contractual term, secured by first liens on real property. • Business lending is comprised of general purpose commercial and industrial loans including, but not limited to, municipal lending, agricultural-related and dealer floor plans, as well as mortgages on commercial properties. • Consumer indirect consists primarily of installment loans originated through selected dealerships and are secured by automobiles, marine and other recreational vehicles. • Consumer direct consists of all other loans to consumers such as personal installment loans and lines of credit. • Home equity products are consumer purpose installment loans or lines of credit most often secured by a first or second lien position on residential real estate with terms up to 30 years. The balances of these classes are summarized as follows: (000's omitted) March 31, 2019 December 31, 2018 Business lending $ 2,410,477 $ 2,396,977 Consumer mortgage 2,237,430 2,235,408 Consumer indirect 1,070,840 1,083,207 Consumer direct 173,042 178,820 Home equity 374,297 386,709 Gross loans, including deferred origination costs 6,266,086 6,281,121 Allowance for loan losses (49,107 ) (49,284 ) Loans, net of allowance for loan losses $ 6,216,979 $ 6,231,837 The outstanding balance related to credit impaired acquired loans was $7.3 million and $7.4 million at March 31, 2019 and December 31, 2018, respectively. The changes in the accretable discount related to the credit impaired acquired loans are as follows: (000’s omitted) Balance at December 31, 2018 $ 437 Accretion recognized, year-to-date (74 ) Balance at March 31, 2019 $ 363 Credit Quality Management monitors the credit quality of its loan portfolio on an ongoing basis. Measurement of delinquency and past due status are based on the contractual terms of each loan. Past due loans are reviewed on a monthly basis to identify loans for non-accrual status. The following is an aged analysis of the Company’s past due loans, by class as of March 31, 2019: Legacy Loans (000’s omitted) Past Due 30 – 89 Days 90+ Days Past Due and Still Accruing Nonaccrual Total Past Due Current Total Loans Business lending $ 6,042 $ 68 $ 4,147 $ 10,257 $ 1,652,950 $ 1,663,207 Consumer mortgage 8,937 1,960 9,794 20,691 1,843,754 1,864,445 Consumer indirect 9,824 201 0 10,025 1,051,493 1,061,518 Consumer direct 985 41 0 1,026 169,334 170,360 Home equity 1,005 323 1,583 2,911 301,113 304,024 Total $ 26,793 $ 2,593 $ 15,524 $ 44,910 $ 5,018,644 $ 5,063,554 Acquired Loans (000’s omitted) Past Due 30 – 89 Days 90+ Days Past Due and Still Accruing Nonaccrual Total Past Due Acquired Impaired (1) Current Total Loans Business lending $ 2,526 $ 66 $ 3,254 $ 5,846 $ 5,342 $ 736,082 $ 747,270 Consumer mortgage 883 287 1,954 3,124 0 369,861 372,985 Consumer indirect 32 33 0 65 0 9,257 9,322 Consumer direct 33 25 0 58 0 2,624 2,682 Home equity 558 15 520 1,093 0 69,180 70,273 Total $ 4,032 $ 426 $ 5,728 $ 10,186 $ 5,342 $ 1,187,004 $ 1,202,532 (1) Acquired impaired loans were not classified as nonperforming assets as the loans are considered to be performing under ASC 310-30. As a result interest income, through the accretion of the difference between the carrying amount of the loans and the expected cashflows, is being recognized on all acquired impaired loans. The following is an aged analysis of the Company’s past due loans by class as of December 31, 2018: Legacy Loans (000’s omitted) Past Due 30 – 89 Days 90+ Days Past Due and Still Accruing Nonaccrual Total Past Due Current Total Loans Business lending $ 5,261 $ 179 $ 4,872 $ 10,312 $ 1,608,515 $ 1,618,827 Consumer mortgage 12,468 1,393 9,872 23,733 1,824,717 1,848,450 Consumer indirect 14,609 258 0 14,867 1,057,525 1,072,392 Consumer direct 1,778 48 0 1,826 173,948 175,774 Home equity 983 228 1,438 2,649 309,892 312,541 Total $ 35,099 $ 2,106 $ 16,182 $ 53,387 $ 4,974,597 $ 5,027,984 Acquired Loans (000’s omitted) Past Due 30 – 89 Days 90+ Days Past Due and Still Accruing Nonaccrual Total Past Due Acquired Impaired (1) Current Total Loans Business lending $ 974 $ 0 $ 3,498 $ 4,472 $ 5,446 $ 768,232 $ 778,150 Consumer mortgage 841 232 2,390 3,463 0 383,495 386,958 Consumer indirect 78 34 0 112 0 10,703 10,815 Consumer direct 115 4 0 119 0 2,927 3,046 Home equity 613 79 474 1,166 0 73,002 74,168 Total $ 2,621 $ 349 $ 6,362 $ 9,332 $ 5,446 $ 1,238,359 $ 1,253,137 (1) Acquired impaired loans were not classified as nonperforming assets as the loans are considered to be performing under ASC 310-30. As a result interest income, through the accretion of the difference between the carrying amount of the loans and the expected cashflows, is being recognized on all acquired impaired loans. The Company uses several credit quality indicators to assess credit risk in an ongoing manner. The Company’s primary credit quality indicator for its business lending portfolio is an internal credit risk rating system that categorizes loans as “pass”, “special mention”, “classified”, or “doubtful”. Credit risk ratings are applied individually to those classes of loans that have significant or unique credit characteristics that benefit from a case-by-case evaluation. In general, the following are the definitions of the Company’s credit quality indicators: Pass The condition of the borrower and the performance of the loans are satisfactory or better. Special Mention The condition of the borrower has deteriorated although the loan performs as agreed. Classified The condition of the borrower has significantly deteriorated and the performance of the loan could further deteriorate, if deficiencies are not corrected. Doubtful The condition of the borrower has deteriorated to the point that collection of the balance is improbable based on current facts and conditions. The following table shows the amount of business lending loans by credit quality category: March 31, 2019 December 31, 2018 (000’s omitted) Legacy Acquired Total Legacy Acquired Total Pass $ 1,475,145 $ 659,645 $ 2,134,790 $ 1,439,337 $ 702,493 $ 2,141,830 Special mention 108,129 53,562 161,691 105,065 40,107 145,172 Classified 79,933 28,721 108,654 74,425 28,525 102,950 Doubtful 0 0 0 0 1,579 1,579 Acquired impaired 0 5,342 5,342 0 5,446 5,446 Total $ 1,663,207 $ 747,270 $ 2,410,477 $ 1,618,827 $ 778,150 $ 2,396,977 All other loans are underwritten and structured using standardized criteria and characteristics, primarily payment performance, and are normally risk rated and monitored collectively on a monthly basis. These are typically loans to individuals in the consumer categories and are delineated as either performing or nonperforming. Performing loans include loans classified as current as well as those classified as 30 - 89 days past due. Nonperforming loans include 90+ days past due and still accruing and nonaccrual loans. The following table details the balances in all other loan categories at March 31, 2019: Legacy Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 1,852,691 $ 1,061,317 $ 170,319 $ 302,118 $ 3,386,445 Nonperforming 11,754 201 41 1,906 13,902 Total $ 1,864,445 $ 1,061,518 $ 170,360 $ 304,024 $ 3,400,347 Acquired Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 370,744 $ 9,289 $ 2,657 $ 69,738 $ 452,428 Nonperforming 2,241 33 25 535 2,834 Total $ 372,985 $ 9,322 $ 2,682 $ 70,273 $ 455,262 The following table details the balances in all other loan categories at December 31, 2018: Legacy Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 1,837,185 $ 1,072,134 $ 175,726 $ 310,875 $ 3,395,920 Nonperforming 11,265 258 48 1,666 13,237 Total $ 1,848,450 $ 1,072,392 $ 175,774 $ 312,541 $ 3,409,157 Acquired Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 384,336 $ 10,781 $ 3,042 $ 73,615 $ 471,774 Nonperforming 2,622 34 4 553 3,213 Total $ 386,958 $ 10,815 $ 3,046 $ 74,168 $ 474,987 All loan classes are collectively evaluated for impairment except business lending. A summary of individually evaluated impaired loans as of March 31, 2019 and December 31, 2018 follows: (000’s omitted) March 31, 2019 December 31, 2018 Loans with allowance allocation $ 0 $ 3,956 Loans without allowance allocation 5,118 2,230 Carrying balance 5,118 6,186 Contractual balance 12,052 12,078 Specifically allocated allowance 0 956 In the course of working with borrowers, the Company may choose to restructure the contractual terms of certain loans. In this scenario, the Company attempts to work-out an alternative payment schedule with the borrower in order to optimize collectability of the loan. Any loans that are modified are reviewed by the Company to identify if a troubled debt restructuring (“TDR”) has occurred, which is when, for economic or legal reasons related to a borrower’s financial difficulties, the Company grants a concession to the borrower that it would not otherwise consider. Terms may be modified to fit the ability of the borrower to repay in line with its current financial standing and the restructuring of the loan may include the transfer of assets from the borrower to satisfy the debt, a modification of loan terms, or a combination of the two. In accordance with the clarified guidance issued by the Office of the Comptroller of the Currency (“OCC”), loans that have been discharged in Chapter 7 bankruptcy but not reaffirmed by the borrower, are classified as TDRs, irrespective of payment history or delinquency status, even if the repayment terms for the loan have not been otherwise modified. The Company’s lien position against the underlying collateral remains unchanged. Pursuant to that guidance, the Company records a charge-off equal to any portion of the carrying value that exceeds the net realizable value of the collateral. The amount of loss incurred in the three months ended March 31, 2019 and 2018 was immaterial. TDRs that are less than $0.5 million are collectively included in the general loan loss allocation and the qualitative review. TDRs that are commercial loans and greater than $0.5 million are individually evaluated for impairment, and if necessary, a specific allocation of the allowance for loan losses is provided. As a result, the determination of the amount of allowance for loan losses related to TDRs is the same as detailed in the critical accounting policies. Information regarding TDRs as of March 31, 2019 and December 31, 2018 is as follows: March 31, 2019 December 31, 2018 (000’s omitted) Nonaccrual Accruing Total Nonaccrual Accruing Total # Amount # Amount # Amount # Amount # Amount # Amount Business lending 3 $ 87 2 $ 161 5 $ 248 4 $ 162 2 $ 165 6 $ 327 Consumer mortgage 50 2,214 50 2,027 100 4,241 46 1,986 46 1,769 92 3,755 Consumer indirect 0 0 85 916 85 916 0 0 77 857 77 857 Consumer direct 0 0 15 1 15 1 0 0 22 71 22 71 Home equity 13 233 9 270 22 503 12 240 9 275 21 515 Total 66 $ 2,534 161 $ 3,375 227 $ 5,909 62 $ 2,388 156 $ 3,137 218 $ 5,525 The following table presents information related to loans modified in a TDR during the three months ended March 31, 2019 and 2018. Of the loans noted in the table below, all loans for the three months ended March 31, 2019 and 2018 were modified due to a Chapter 7 bankruptcy as described previously. The financial effects of these restructurings were immaterial Three Months Ended March 31, 2019 Three Months Ended March 31, 2018 (000’s omitted) Number of loans modified Outstanding Balance Number of loans modified Outstanding Balance Business lending 0 $ 0 1 $ 93 Consumer mortgage 8 665 0 0 Consumer indirect 11 98 4 41 Consumer direct 0 0 2 2 Home equity 1 4 0 0 Total 20 $ 767 7 $ 136 Allowance for Loan Losses The allowance for loan losses is general in nature and is available to absorb losses from any loan type despite the analysis below. The following presents by class the activity in the allowance for loan losses: Three Months Ended (000’s omitted) Business Lending Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Unallocated Acquired Impaired Total Beginning balance $ 18,522 $ 10,124 $ 14,366 $ 3,095 $ 2,144 $ 1,000 $ 33 $ 49,284 Charge-offs (1,216 ) (253 ) (1,823 ) (535 ) (74 ) 0 0 (3,901 ) Recoveries 134 22 962 179 5 0 0 1,302 Provision 831 424 746 317 (8 ) (10 ) 122 2,422 Ending balance $ 18,271 $ 10,317 $ 14,251 $ 3,056 $ 2,067 $ 990 $ 155 $ 49,107 Three Months Ended (000’s omitted) Business Lending Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Unallocated Acquired Impaired Total Beginning balance $ 17,257 $ 10,465 $ 13,468 $ 3,039 $ 2,107 $ 1,100 $ 147 $ 47,583 Charge-offs (1,669 ) (199 ) (2,284 ) (496 ) (56 ) 0 (43 ) (4,747 ) Recoveries 198 8 1,151 222 9 0 0 1,588 Provision 1,821 108 1,363 219 (20 ) (16 ) 204 3,679 Ending balance $ 17,607 $ 10,382 $ 13,698 $ 2,984 $ 2,040 $ 1,084 $ 308 $ 48,103

GOODWILL AND IDENTIFIABLE INTAN

GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS	3 Months Ended
	Mar. 31, 2019
GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS [Abstract]
GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS	NOTE F: GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS The gross carrying amount and accumulated amortization for each type of identifiable intangible asset are as follows: March 31, 2019 December 31, 2018 (000's omitted) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Amortizing intangible assets: Core deposit intangibles $ 62,902 $ (45,789 ) $ 17,113 $ 62,902 $ (44 , ) $ 18 , Other intangibles 88,816 (35,013 ) 53,803 87 , (32 , ) 55 , Total amortizing intangibles $ 151,718 $ (80,802 ) $ 70,916 $ 150 , $ (76 , ) $ 73 , The estimated aggregate amortization expense for each of the five succeeding fiscal years ended December 31 is as follows: (000's omitted) Apr - Dec 2019 $ 11,433 2020 12,956 2021 11,053 2022 9,483 2023 7,947 Thereafter 18,044 Total $ 70,916 Shown below are the components of the Company’s goodwill at December 31, 2018 and March 31, 2019: (000’s omitted) December 31, 2018 Activity March 31, 2019 Goodwill $ 738,327 $ 0 $ 738,327 Accumulated impairment (4,824 ) 0 (4,824 ) Goodwill, net $ 733,503 $ 0 $ 733,503

LEASES

LEASES	3 Months Ended
	Mar. 31, 2019
LEASES [Abstract]
LEASES	NOTE G: LEASES The Company has operating leases for certain offices and certain equipment. These leases have remaining terms that range from less than one year to 16 years. Options to extend the leases range from a single extension option of one year to multiple extension options for up to 40 years. Certain agreements include an option to terminate the lease within one year. The components of lease expense are as follows: (000’s omitted) Three Months Ended March 31, 2019 Operating lease cost $ 2,117 Short-term lease cost (1) 54 Total lease cost $ 2,171 (1) Short-term lease cost includes the cost of leases with terms of twelve months or less, excluding leases with terms of one month or less. Supplemental cash flow information related to leases is as follows: (000’s omitted) Three Months Ended March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash outflows for operating leases $ 2,030 Right-of-use assets obtained in exchange for lease obligations: Operating leases 2,969 Supplemental balance sheet information related to leases is as follows: (000’s omitted, except lease term and discount rate) Three Months Ended March 31, 2019 Operating leases Operating lease right-of-use assets $ 34,956 Operating lease liabilities 35,630 Weighted average remaining lease term Operating leases 6.7 years Weighted average discount rate Operating leases 3.26 % Maturities of lease liabilities as of March 31, 2019 are as follows: (000’s omitted) Operating Leases Apr - Dec 2019 $ 6,534 2020 7,967 2021 6,396 2022 5,143 2023 3,393 Thereafter 10,653 Total lease payments 40,086 Less imputed interest (4,456 ) Total $ 35,630 Included in the Company’s operating leases are related party leases where BPAS Actuarial & Pension Services, LLC and OneGroup NY, Inc., subsidiaries of the Company, lease office space from 706 North Clinton, LLC., an entity the Company holds a 50% membership interest in through its subsidiary Oneida Preferred Funding II, LLC. The operating lease right-of-use assets and operating lease liabilities associated with these related party leases total $5.2 million and $5.2 million, respectively. The weighted average remaining lease term and weighted average discount rate for these leases are 10.7 years and 3.67%, respectively. The maturities of the Company’s related party lease liabilities as of March 31, 2019 are as follows: (000’s omitted) 706 North Clinton, LLC Apr - Dec 2019 $ 443 2020 591 2021 591 2022 591 2023 591 Thereafter 3,538 Total lease payments 6,345 Less imputed interest (1,105 ) Total $ 5,240 As of March 31, 2019, the Company has an immaterial amount of additional operating leases for offices and equipment that have not yet commenced.

MANDATORILY REDEEMABLE PREFERRE

MANDATORILY REDEEMABLE PREFERRED SECURITIES	3 Months Ended
	Mar. 31, 2019
MANDATORILY REDEEMABLE PREFERRED SECURITIES [Abstract]
MANDATORILY REDEEMABLE PREFERRED SECURITIES	NOTE H: MANDATORILY REDEEMABLE PREFERRED SECURITIES The Company sponsors two business trusts, Community Capital Trust IV (“CCT IV”) and MBVT Statutory Trust I (“MBVT I”), of which 100% of the common stock is owned by the Company. The common stock of MBVT Statutory Trust I was acquired in the Merchants Bancshares, Inc. (“Merchants”) acquisition. The trusts were formed for the purpose of issuing company-obligated mandatorily redeemable preferred securities to third-party investors and investing the proceeds from the sale of such preferred securities solely in junior subordinated debt securities of the Company. The debentures held by each trust are the sole assets of such trust. Distributions on the preferred securities issued by each trust are payable quarterly at a rate per annum equal to the interest rate being earned by the trust on the debentures held by that trust and are recorded as interest expense in the consolidated financial statements. The preferred securities are subject to mandatory redemption, in whole or in part, upon repayment of the debentures. The Company has entered into agreements which, taken collectively, fully and unconditionally guarantee the preferred securities subject to the terms of each of the guarantees. The terms of the preferred securities of each trust are as follows: Trust Issuance Date Par Amount Interest Rate Maturity Date Call Price CCT IV 12/8/2006 $75.0 million 3 month LIBOR plus 1.65% (4.26%) 12/15/2036 Par MBVT I 12/15/2004 $20.6 million 3 month LIBOR plus 1.95% (4.56%) 12/31/2034 Par

BENEFIT PLANS

BENEFIT PLANS	3 Months Ended
	Mar. 31, 2019
BENEFIT PLANS [Abstract]
BENEFIT PLANS	NOTE I: BENEFIT PLANS The Company provides a qualified defined benefit pension to eligible employees and retirees, other post-retirement health and life insurance benefits to certain retirees, an unfunded supplemental pension plan for certain key executives, and an unfunded stock balance plan for certain of its nonemployee directors. The Company accrues for the estimated cost of these benefits through charges to expense during the years that employees earn these benefits. The service cost component of net periodic benefit income is included in the salaries and employee benefits line of the Consolidated Statements of Income, while the other components of net periodic benefit income are included in other expenses. The Company made a $7.3 million contribution to its defined benefit pension plan in the first quarter of 2019. Effective June 1, 2018, the Company adopted the Community Bank System, Inc. Restoration Plan (“Restoration Plan”). The Restoration Plan is a non-qualified deferred compensation plan for certain employees whose benefits under tax-qualified retirement plans are restricted by the Internal Revenue Code Section 401(a)(17) limitation on compensation. Adoption of the plan resulted in an unfunded initial projected benefit obligation of approximately $0.8 million that will be amortized over the average expected future years of service of active plan participants. The net periodic benefit cost for the three months ended March 31, 2019 and 2018 is as follows: Pension Benefits Post-retirement Benefits Three Months Ended March 31, Three Months Ended March 31, (000's omitted) 2019 2018 2019 2018 Service cost $ 1,270 $ 1,121 $ 0 $ 0 Interest cost 1,566 1,415 18 17 Expected return on plan assets (3,577 ) (3,705 ) 0 0 Amortization of unrecognized net loss 642 298 9 5 Amortization of prior service cost 16 (83 ) (45 ) (44 ) Net periodic benefit $ (83 ) $ (954 ) $ (18 ) $ (22 )

EARNINGS PER SHARE

EARNINGS PER SHARE	3 Months Ended
	Mar. 31, 2019
EARNINGS PER SHARE [Abstract]
EARNINGS PER SHARE	NOTE J: EARNINGS PER SHARE The two class method is used in the calculations of basic and diluted earnings per share. Under the two class method, earnings available to common shareholders for the period are allocated between common shareholders and participating securities according to dividends declared and participation rights in undistributed earnings. The Company has determined that all of its outstanding non-vested stock awards are participating securities as of March 31, 2019. Basic earnings per share are computed based on the weighted-average of the common shares outstanding for the period. Diluted earnings per share are based on the weighted-average of the shares outstanding and the assumed exercise of stock options during the year. The dilutive effect of options is calculated using the treasury stock method of accounting. The treasury stock method determines the number of common shares that would be outstanding if all the dilutive options (those where the average market price is greater than the exercise price) were exercised and the proceeds were used to repurchase common shares in the open market at the average market price for the applicable time period. There were approximately 0.5 million weighted-average anti-dilutive stock options outstanding for the three months ended March 31, 2019, compared to approximately 0.4 million weighted-average anti-dilutive stock options outstanding for the three months ended March 31, 2018 that were not included in the computation below. The following is a reconciliation of basic to diluted earnings per share for the three months ended March 31, 2019 and 2018: Three Months Ended March 31, (000's omitted, except per share data) 2019 2018 Net income $ 41,946 $ 40,106 Income attributable to unvested stock-based compensation awards (109 ) (141 ) Income available to common shareholders $ 41,837 $ 39,965 Weighted-average common shares outstanding – basic 51,520 50,934 Basic earnings per share $ 0.81 $ 0.78 Net income $ 41,946 $ 40,106 Income attributable to unvested stock-based compensation awards (109 ) (141 ) Income available to common shareholders $ 41,837 $ 39,965 Weighted-average common shares outstanding 51,520 50,934 Assumed exercise of stock options 541 563 Weighted-average common shares outstanding – diluted 52,061 51,497 Diluted earnings per share $ 0.80 $ 0.78 Stock Repurchase Program At its December 2017 meeting, the Company’s Board of Directors (the “Board”) approved a stock repurchase program authorizing the repurchase of up to 2.5 million shares of the Company’s common stock in accordance with securities laws and regulations, through December 31, 2018. At its December 2018 meeting, the Board approved a similar program for 2019, authorizing the repurchase of up to 2.5 million shares of the Company’s common stock through December 31, 2019. Any repurchased shares will be used for general corporate purposes, including those related to stock plan activities. The timing and extent of repurchases will depend on market conditions and other corporate considerations as determined at the Company’s discretion. The Company did not repurchase any shares under the authorized plan during the first three months of 2019 or 2018.

COMMITMENTS, CONTINGENT LIABILI

COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS	3 Months Ended
	Mar. 31, 2019
COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS [Abstract]
COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS	NOTE K: COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS The Company is a party to financial instruments with off-balance sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments consist primarily of commitments to extend credit and standby letters of credit. Commitments to extend credit are agreements to lend to customers, generally having fixed expiration dates or other termination clauses that may require payment of a fee. These commitments consist principally of unused commercial and consumer credit lines. Standby letters of credit generally are contingent upon the failure of the customer to perform according to the terms of an underlying contract with a third party. The credit risks associated with commitments to extend credit and standby letters of credit are essentially the same as that involved with extending loans to customers and are subject to the Company’s normal credit policies. Collateral may be obtained based on management’s assessment of the customer’s creditworthiness. The fair value of the standby letters of credit is immaterial for disclosure. The contract amounts of commitments and contingencies are as follows: (000's omitted) March 31, 2019 December 31, 2018 Commitments to extend credit $ 1,047,047 $ 1,134 , Standby letters of credit 36,485 33 , Total $ 1,083,532 $ 1,167 , The Company and its subsidiaries are subject in the normal course of business to various pending and threatened legal proceedings in which claims for monetary damages are asserted. As of March 31, 2019, management, after consultation with legal counsel, does not anticipate that the aggregate ultimate liability arising out of litigation pending or threatened against the Company or its subsidiaries will be material to the Company’s consolidated financial position. On at least a quarterly basis, the Company assesses its liabilities and contingencies in connection with such legal proceedings. For those matters where it is probable that the Company will incur losses and the amounts of the losses can be reasonably estimated, the Company records an expense and corresponding liability in its consolidated financial statements. To the extent the pending or threatened litigation could result in exposure in excess of that liability, the amount of such excess is not currently estimable. The range of reasonably possible losses for matters where an exposure is not currently estimable or considered probable, beyond the existing recorded liabilities, is between $0 and $1 million in the aggregate. Although the Company does not believe that the outcome of pending litigation will be material to the Company’s consolidated financial position, it cannot rule out the possibility that such outcomes will be material to the consolidated results of operations for a particular reporting period in the future.

FAIR VALUE

FAIR VALUE	3 Months Ended
	Mar. 31, 2019
FAIR VALUE [Abstract]
FAIR VALUE	NOTE L: FAIR VALUE Accounting standards establish a framework for measuring fair value and require certain disclosures about such fair value instruments. It defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (i.e. exit price). Inputs used to measure fair value are classified into the following hierarchy: • Level 1 - Quoted prices in active markets for identical assets or liabilities. • Level 2 - Quoted prices in active markets for similar assets or liabilities, or quoted prices for identical or similar assets or liabilities in markets that are not active, or inputs other than quoted prices that are observable for the asset or liability. • Level 3 - Significant valuation assumptions not readily observable in a market. A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The following tables set forth the Company’s financial assets and liabilities that were accounted for at fair value on a recurring basis. There were no transfers between any of the levels for the periods presented. March 31, 2019 (000's omitted) Level 1 Level 2 Level 3 Total Fair Value Available-for-sale investment securities: U.S. Treasury and agency securities $ 1,913,361 $ 121,611 $ 0 $ 2,034,972 Obligations of state and political subdivisions 0 433 , 0 433 , Government agency mortgage-backed securities 0 386 , 0 386 , Corporate debt securities 0 2,553 0 2,553 Government agency collateralized mortgage obligations 0 65 , 0 65 , Total available-for-sale investment securities 1,913,361 1,009,582 0 2,922,943 Equity securities 464 0 0 464 Mortgage loans held for sale 0 212 0 212 Commitments to originate real estate loans for sale 0 0 20 20 Forward sales commitments 0 (6 ) 0 (6 ) Interest rate swap agreements asset 0 835 0 835 Interest rate swap agreements liability 0 (705 ) 0 (705 ) Total $ 1,913,825 $ 1,009,918 $ 20 $ 2,923,763 December 31, 2018 (000's omitted) Level 1 Level 2 Level 3 Total Fair Value Available-for-sale investment securities: U.S. Treasury and agency securities $ 1,896,931 $ 126,822 $ 0 $ 2,023 , Obligations of state and political subdivisions 0 459,154 0 459 , Government agency mortgage-backed securities 0 382,477 0 382 , Corporate debt securities 0 2,546 0 2,546 Government agency collateralized mortgage obligations 0 68,119 0 68 , Total available-for-sale investment securities 1,896,931 1,039,118 0 2,936,049 Equity securities 432 0 0 432 Mortgage loans held for sale 0 83 0 83 Interest rate swap agreements asset 0 793 0 793 Interest rate swap agreements liability 0 (742 ) 0 (742 ) Total $ 1,897,363 $ 1,039,252 $ 0 $ 2,936,615 The valuation techniques used to measure fair value for the items in the table above are as follows: • Available-for-sale investment securities and equity securities – The fair values of available-for-sale investment securities are based upon quoted prices, if available. If quoted prices are not available, fair values are measured using quoted market prices for similar securities or model-based valuation techniques. Level 1 securities include U.S. Treasury obligations and marketable equity securities that are traded by dealers or brokers in active over-the-counter markets. Level 2 securities include U.S. agency securities, mortgage-backed securities issued by government-sponsored entities, municipal securities and corporate debt securities that are valued by reference to prices for similar securities or through model-based techniques in which all significant inputs, such as reported trades, trade execution data, LIBOR swap yield curve, market prepayment speeds, credit information, market spreads, and security’s terms and conditions, are observable. See Note D for further disclosure of the fair value of investment securities. • Mortgage loans held for sale – The Company has elected to value loans held for sale at fair value in order to more closely match the gains and losses associated with loans held for sale with the gains and losses on forward sales contracts. Accordingly, the impact on the valuation will be recognized in the Company’s consolidated statement of income. All mortgage loans held for sale are current and in performing status. The fair value of mortgage loans held for sale is determined using quoted secondary-market prices of loans with similar characteristics and, as such, has been classified as a Level 2 valuation. The unpaid principal value of mortgage loans held for sale was approximately $0.2 million and $0.1 million at March 31, 2019 and December 31, 2018, respectively. The unrealized gain on mortgage loans held for sale was recognized in other banking revenues in the consolidated statements of income and is immaterial. • Forward sales commitments – The Company enters into forward sales commitments to sell certain residential real estate loans. Such commitments are considered to be derivative financial instruments and, therefore, are carried at estimated fair value in the other asset or other liability section of the consolidated statement of condition. The fair value of these forward sales commitments is primarily measured by obtaining pricing from certain government-sponsored entities and reflects the underlying price the entity would pay the Company for an immediate sale on these mortgages. As such, these instruments are classified as Level 2 in the fair value hierarchy. • Commitments to originate real estate loans for sale – The Company enters into various commitments to originate residential real estate loans for sale. Such commitments are considered to be derivative financial instruments and, therefore, are carried at estimated fair value in the other asset or other liability section of the consolidated statement of condition. The estimated fair value of these commitments is determined using quoted secondary market prices obtained from certain government-sponsored entities. Additionally, accounting guidance requires the expected net future cash flows related to the associated servicing of the loan to be included in the fair value measurement of the derivative. The expected net future cash flows are based on a valuation model that calculates the present value of estimated net servicing income. The valuation model incorporates assumptions that market participants would use in estimating future net servicing income. Such assumptions include estimates of the cost of servicing loans, appropriate discount rate and prepayment speeds. The determination of expected net cash flows is considered a significant unobservable input contributing to the Level 3 classification of commitments to originate real estate loans for sale. • Interest rate swaps – The interest rate swaps are reported at their fair value utilizing Level 2 inputs from third parties. The fair value of the interest rate swaps are determined using prices obtained from a third party advisor. The fair value measurement of the interest rate swap is determined by netting the discounted future fixed cash payments and the discounted expected variable cash receipts. The variable cash receipts are based on the expectation of future interest rates derived from observed market interest rate curves. The changes in Level 3 assets measured at fair value on a recurring basis are immaterial. The fair value information of assets and liabilities measured on a non-recurring basis presented below is not as of the period-end, but rather as of the date the fair value adjustment was recorded closest to the date presented. March 31, 2019 December 31, 2018 (000's omitted) Level 1 Level 2 Level 3 Total Fair Value Level 1 Level 2 Level 3 Total Fair Value Impaired loans $ 0 $ 0 $ 2,831 $ 2,831 $ 0 $ 0 $ 1,102 $ 1,102 Other real estate owned 0 0 1,524 1,524 0 0 1,320 1,320 Total $ 0 $ 0 $ 4,355 $ 4,355 $ 0 $ 0 $ 2,422 $ 2,422 Loans are generally not recorded at fair value on a recurring basis. Periodically, the Company records nonrecurring adjustments to the carrying value of loans based on fair value measurements for partial charge-offs of the uncollectible portions of those loans. Nonrecurring adjustments also include certain impairment amounts for collateral-dependent loans calculated when establishing the allowance for loan losses. Such amounts are generally based on the fair value of the underlying collateral supporting the loan and, as a result, the carrying value of the loan less the calculated valuation amount does not necessarily represent the fair value of the loan. Real estate collateral is typically valued using independent appraisals or other indications of value based on recent comparable sales of similar properties or assumptions generally observable in the marketplace, adjusted for non-observable inputs. Thus, the resulting nonrecurring fair value measurements are generally classified as Level 3. Estimates of fair value used for other collateral supporting commercial loans generally are based on assumptions not observable in the marketplace and, therefore, such valuations classify as Level 3. Other real estate owned (“OREO”) is valued at the time the loan is foreclosed upon and the asset is transferred to OREO. The value is based primarily on third party appraisals, less costs to sell. The appraisals are sometimes further discounted based on management’s historical knowledge, changes in market conditions from the time of valuation, and/or management’s expertise and knowledge of the customer and customer’s business. Such discounts are significant, ranging from 9.0% to 75.8% at March 31, 2019 and result in a Level 3 classification of the inputs for determining fair value. OREO is reviewed and evaluated on at least a quarterly basis for additional impairment and adjusted accordingly, based on the same factors identified above. The Company recovers the carrying value of OREO through the sale of the property. The ability to affect future sales prices is subject to market conditions and factors beyond the Company’s control and may impact the estimated fair value of a property. Originated mortgage servicing rights are recorded at their fair value at the time of sale of the underlying loan, and are amortized in proportion to and over the estimated period of net servicing income. The fair value of mortgage servicing rights is based on a valuation model incorporating inputs that market participants would use in estimating future net servicing income. Such inputs include estimates of the cost of servicing loans, appropriate discount rate and prepayment speeds and are considered to be unobservable and contribute to the Level 3 classification of mortgage servicing rights. In accordance with GAAP, the Company must record impairment charges, on a nonrecurring basis, when the carrying value of a stratum exceeds its estimated fair value. Impairment is recognized through a valuation allowance. There is no valuation allowance at March 31, 2019. The Company determines fair values based on quoted market values, where available, estimates of present values, or other valuation techniques. Those techniques are significantly affected by the assumptions used, including, but not limited to, the discount rate and estimates of future cash flows. In that regard, the derived fair value estimates cannot be substantiated by comparison to independent markets and, in many cases, may not be realized in immediate settlement of the instrument. The significant unobservable inputs used in the determination of fair value of assets classified as Level 3 on a recurring or non-recurring basis are as follows: (000's omitted) Fair Value at March 31, 2019 Valuation Technique Significant Unobservable Inputs Significant Unobservable Input Range (Weighted Average) Impaired loans $ 2 , Fair value of collateral Estimated cost of disposal/market adjustment 9.0% - 40.4% (35 .0 %) Other real estate owned 1,524 Fair value of collateral Estimated cost of disposal/market adjustment 9.0% - 75.8% (23 . %) Commitments to originate real estate loans for sale 20 Discounted cash flow Embedded servicing value 1 % (000's omitted) Fair Value at December 31, 2018 Valuation Technique Significant Unobservable Inputs Significant Unobservable Input Range (Weighted Average) Impaired loans $ 1,102 Fair value of collateral Estimated cost of disposal/market adjustment 9.0% - 35 . %) Other real estate owned 1,320 Fair value of collateral Estimated cost of disposal/market adjustment 9.0% - 69 . . %) Certain financial instruments and all nonfinancial instruments are excluded from fair value disclosure requirements. Accordingly, the aggregate fair value amounts presented do not represent the underlying value of the Company. The carrying amounts and estimated fair values of the Company’s other financial instruments that are not accounted for at fair value at March 31, 2019 and December 31, 2018 are as follows: March 31, 2019 December 31, 2018 (000's omitted) Carrying Value Fair Value Carrying Value Fair Value Financial assets: Net loans $ 6,216,979 $ 6,266 , $ 6,231 , $ 6,247 , Financial liabilities: Deposits 8,619 , 8,607 , 8,322 , 8,308 , Short-term borrowings 0 0 54,4 00 54 , Securities sold under agreement to repurchase, short-term 249 , 249,880 259 , 259 , Other long-term debt 1 , 1,914 1 , 1 , Subordinated debt held by unconsolidated subsidiary trusts 97 , 97 , 97 , 97 , The following is a further description of the principal valuation methods used by the Company to estimate the fair values of its financial instruments. Loans have been classified as a Level 3 valuation. Fair values for variable rate loans that reprice frequently are based on carrying values. Fair values for fixed rate loans are estimated using discounted cash flows and interest rates currently being offered for loans with similar terms to borrowers of similar credit quality. Deposits have been classified as a Level 2 valuation. The fair value of demand deposits, interest-bearing checking deposits, savings accounts, and money market deposits is the amount payable on demand at the reporting date. The fair value of time deposit obligations are based on current market rates for similar products. Borrowings and subordinated debt held by unconsolidated subsidiary trusts have been classified as a Level 2 valuation. The fair value of short-term borrowings and securities sold under agreement to repurchase, short-term, is the amount payable on demand at the reporting date. Fair values for long-term debt and subordinated debt held by unconsolidated subsidiary trusts are estimated using discounted cash flows and interest rates currently being offered on similar securities. The difference between the carrying values of long-term borrowings and subordinated debt held by unconsolidated subsidiary trusts, and their fair values, are not material as of the reporting dates. Other financial assets and liabilities – Cash and cash equivalents have been classified as a Level 1 valuation, while accrued interest receivable and accrued interest payable have been classified as a Level 2 valuation. The fair values of each approximate the respective carrying values because the instruments are payable on demand or have short-term maturities and present relatively low credit risk and interest rate risk.

DERIVATIVE INSTRUMENTS

DERIVATIVE INSTRUMENTS	3 Months Ended
	Mar. 31, 2019
DERIVATIVE INSTRUMENTS [Abstract]
DERIVATIVE INSTRUMENTS	NOTE M: DERIVATIVE INSTRUMENTS The Company is party to derivative financial instruments in the normal course of its business to meet the financing needs of its customers and to manage its own exposure to fluctuations in interest rates. These financial instruments have been limited to interest rate swap agreements, commitments to originate real estate loans held for sale and forward sales commitments. The Company does not hold or issue derivative financial instruments for trading or other speculative purposes. The Company enters into forward sales commitments for the future delivery of residential mortgage loans, and interest rate lock commitments to fund loans at a specified interest rate. The forward sales commitments are utilized to reduce interest rate risk associated with interest rate lock commitments and loans held for sale. Changes in the estimated fair value of the forward sales commitments and interest rate lock commitments subsequent to inception are based on changes in the fair value of the underlying loan resulting from the fulfillment of the commitment and changes in the probability that the loan will fund within the terms of the commitment, which is affected primarily by changes in interest rates and the passage of time. At inception and during the life of the interest rate lock commitment, the Company includes the expected net future cash flows related to the associated servicing of the loan as part of the fair value measurement of the interest rate lock commitments. These derivatives are recorded at fair value, which were immaterial at March 31, 2019 and December 31, 2018. The effect of the changes to these derivatives for the three months then ended was also immaterial. The Company acquired interest rate swaps from the Merchants acquisition with notional amounts with certain commercial customers which totaled $36.6 million at March 31, 2019 and $37.0 million at December 31, 2018. In order to minimize the Company’s risk, these customer derivatives (pay floating/receive fixed swaps) have been offset with essentially matching interest rate swaps (pay fixed/receive floating swaps) with the Company’s counterparty totaling $36.6 million at March 31, 2019 and $37.0 million at December 31, 2018. At March 31, 2019, the weighted average receive rate of these interest rate swaps was 4.37%, the weighted average pay rate was 3.83% and the weighted average maturity was 5.2 years. At December 31, 2018, the weighted average receive rate of these interest rate swaps was 4.34%, the weighted average pay rate was 3.84% and the weighted average maturity was 5.5 years. Hedge accounting has not been applied for these derivatives. Since the terms of the swaps with the Company’s customer and the other financial institution offset each other, with the only difference being counterparty credit risk, changes in the fair value of the underlying derivative contracts are not materially different and do not significantly impact the Company’s results of operations. The Company also acquired interest rate swaps from the Merchants acquisition with notional amounts totaling $6.6 million at March 31, 2019, and $6.6 million at December 31, 2018, that were designated as fair value hedges of certain fixed rate loans with municipalities which are recorded in loans in the consolidated statements of financial condition. At March 31, 2019, the weighted average receive rate of these interest rate swaps was 2.94%, the weighted average pay rate was 3.11% and the weighted average maturity was 14.3 years. At December 31, 2018, the weighted average receive rate of these interest rate swaps was 2.92%, the weighted average pay rate was 3.11% and the weighted average maturity was 14.5 years. The Company includes the gain or loss on the hedged items in interest and fees on loans, the same line item as the offsetting gain or loss on the related interest rate swaps. The effects of fair value accounting in the consolidated statement of income for the three months ended March 31, 2019 are immaterial. As of March 31, 2019, the following amounts were recorded in the consolidated statement of condition related to cumulative basis adjustments for fair value hedges: (000’s omitted) Statement of Condition in Which the Hedged Item Is Included Carrying Amount of the Hedged Assets Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets March 31, 2019 March 31, 2019 Loans $ 7,006 $ (130 ) Fair values of derivative instruments as of March 31, 2019 are as follows: (000’s omitted) March 31, 2019 Derivative Assets Derivative Liabilities Consolidated Statement of Condition Location Fair Value Consolidated Statement of Condition Location Fair Value Derivatives designated as hedging instruments under Subtopic 815-20 Interest rate swaps Other assets $ 130 Derivatives not designated as hedging instruments under Subtopic 815-20 Interest rate swaps Other assets 705 Accrued interest and other liabilities $ 705 Commitments to originate real estate loans for sale Other assets 20 Forward sales commitments Accrued interest and other liabilities 6 Total derivatives $ 855 $ 711 The Company assessed its counterparty risk at March 31, 2019 and determined any credit risk inherent in our derivative contracts was not material. Further information about the fair value of derivative financial instruments can be found in Note L to these consolidated financial statements.

SEGMENT INFORMATION

SEGMENT INFORMATION	3 Months Ended
	Mar. 31, 2019
SEGMENT INFORMATION [Abstract]
SEGMENT INFORMATION	NOTE N: SEGMENT INFORMATION Operating segments are components of an enterprise, which are evaluated regularly by the “chief operating decision maker” in deciding how to allocate resources and assess performance. The Company’s chief operating decision maker is the President and Chief Executive Officer of the Company. The Company has identified Banking, Employee Benefit Services and All Other as its reportable operating business segments. Community Bank, N.A. (the “Bank” or “CBNA”) operates the Banking segment that provides full-service banking to consumers, businesses, and governmental units in Upstate New York as well as Northeastern Pennsylvania, Vermont and Western Massachusetts. Employee Benefit Services, which includes the operating subsidiaries Benefit Plans Administrative Services, LLC, BPAS Actuarial and Pension Services, LLC, BPAS Trust Company of Puerto Rico, Northeast Retirement Services, LLC (“NRS”), Global Trust Company, Inc. (“GTC”), and Hand Benefits & Trust Company, provides employee benefit trust, collective investment fund, retirement plan administration, fund administration, transfer agency, actuarial, VEBA/HRA, and health and welfare consulting services. The All Other segment is comprised of: (a) wealth management services including trust services provided by the personal trust unit within the Bank, broker-dealer and investment advisory services provided by CISI and The Carta Group, Inc., as well as asset management provided by Nottingham Advisors, Inc., and (b) full-service insurance, risk management and employee benefit services provided by OneGroup. The accounting policies used in the disclosure of business segments are the same as those described in the summary of significant accounting policies (See Note A, Summary of Significant Accounting Policies Information about reportable segments and reconciliation of the information to the consolidated financial statements follows: (000's omitted) Banking Employee Benefit Services All Other Eliminations Consolidated Total Three Months Ended March 31, 2019 Net interest income $ 86,715 $ 108 $ 36 $ 0 $ 86,859 Provision for loan losses 2,422 0 0 0 2,422 Noninterest revenues 17,348 24,670 14,447 (769 ) 55,696 Amortization of intangible assets 1,483 1,769 878 0 4,130 Acquisition expenses 534 0 0 0 534 Other operating expenses 59,769 14,279 10,709 (769 ) 83,988 Income before income taxes $ 39,855 $ 8,730 $ 2,896 $ 0 $ 51,481 Assets $ 10,699,384 $ 199,345 $ 71,047 $ (53,309 ) $ 10,916,467 Goodwill $ 629,916 $ 83,275 $ 20,312 $ 0 $ 733,503 Core deposit intangibles & Other intangibles $ 17,113 $ 42,777 $ 11,026 $ 0 $ 70,916 Three Months Ended March 31, 2018 Net interest income $ 84,530 $ 70 $ 24 $ 0 $ 84,624 Provision for loan losses 3,679 0 0 0 3,679 Noninterest revenues 20,357 23,449 14,380 (695 ) 57,491 Amortization of intangible assets 1,744 2,088 966 0 4,798 Acquisition expenses (15 ) 7 0 0 (8 ) Other operating expenses 56,955 13,709 11,572 (695 ) 81,541 Income before income taxes $ 42,524 $ 7,715 $ 1,866 $ 0 $ 52,105 Assets $ 10,736,383 $ 205,544 $ 68,167 $ (43,539 ) $ 10,966,555 Goodwill $ 629,916 $ 83,275 $ 20,434 $ 0 $ 733,625 Core deposit intangibles & Other intangibles $ 23,281 $ 50,200 $ 13,478 $ 0 $ 86,959

BASIS OF PRESENTATION (Policies

BASIS OF PRESENTATION (Policies)	3 Months Ended
	Mar. 31, 2019
BASIS OF PRESENTATION [Abstract]
Basis of Presentation	The interim financial data as of and for the three months ended March 31, 2019 is unaudited; however, in the opinion of Community Bank System, Inc. (the “Company”), the interim data includes all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the results for the interim periods in conformity with generally accepted accounting principles in the United States of America (“GAAP”). The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period.

ACCOUNTING POLICIES (Policies)

ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2019
ACCOUNTING POLICIES [Abstract]
Leases	Leases The Company occupies certain offices and uses certain equipment under non-cancelable operating lease agreements. The Company determines if an arrangement is a lease at inception. The right-of-use assets associated with operating leases are recorded in premises and equipment in the Company’s consolidated statements of condition. The lease liabilities associated with operating leases are included in accrued interest and other liabilities in the Company’s consolidated statements of condition. Right-of-use assets represent the Company’s right to use the underlying assets for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the associated leases. Operating lease right-of-use assets and liabilities are recognized at the commencement date of the lease based on the present value of lease payments over the lease term. The Company uses interest rates on advances from the Federal Home Loan Bank of New York available at the time of commencement to determine the present value of lease payments. The operating lease right-of-use assets include any lease payments made at the time of commencement and exclude lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Lease expense is recognized on a straight-line basis over the lease term and is included in occupancy and equipment expense in the Company’s consolidated statements of income. The Company elected to account for lease and non-lease components separately, applies a portfolio approach to account for the lease right-of-use assets and liabilities for certain equipment leases and elected to exclude leases with a term of 12 months or less from the recognition and measurement policies described above.
Derivative Financial Instruments and Hedging Activities	Derivative Financial Instruments and Hedging Activities The Company accounts for derivative financial instruments at fair value. If certain conditions are met, a derivative may be specifically designated as (1) a hedge of the exposure to changes in the fair value of a recognized asset or liability or an unrecognized firm commitment (“fair value hedge”), (2) a hedge of the exposure to variable cash flows of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (“cash flow hedge”), or (3) an instrument with no hedging designation (“stand-alone derivative”). For a fair value hedge, the gain or loss on the derivative, as well as the offsetting loss or gain on the hedged item, are recognized in current earnings as fair values change. For a cash flow hedge, the gain or loss on the derivative is reported in other comprehensive income and is reclassified into earnings in the same periods during which the hedged transaction affects earnings. Changes in the fair value of derivatives that do not qualify for hedge accounting are reported currently in earnings, as noninterest revenues. Net cash settlements on derivatives that qualify for hedge accounting are recorded in interest income or interest expense, based on the item being hedged. Net cash settlements on derivatives that do not qualify for hedge accounting are reported in noninterest revenues. Cash flows on hedges are classified in the consolidated statement of cash flow statement the same as the cash flows of the items being hedged. The Company formally documents the relationship between derivatives and hedged items, as well as the risk-management objective and strategy for undertaking hedge transactions at the inception of the hedging relationship. This documentation includes linking the fair value or cash flow hedges to specific assets and liabilities on the statement of condition or to specific commitments or forecasted transactions. The Company also formally assesses, both at the hedge’s inception and on an ongoing basis, whether the derivative instruments that are used are highly effective in offsetting changes in fair values or cash flows of the hedged items. When hedge accounting is discontinued, subsequent changes in fair value of the derivative are recorded in noninterest revenues. When a fair value hedge is discontinued, the hedged asset or liability is no longer adjusted for changes in fair value and the existing basis adjustment is amortized or accreted over the remaining life of the asset or liability. When a cash flow hedge is discontinued, but the hedged cash flows or forecasted transactions are still expected to occur, gains or losses that were accumulated in other comprehensive income are amortized into earnings over the same periods which the hedged transactions will affect earnings.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) Topic 840, Leases In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.
New Accounting Pronouncements	New Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326) In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350)

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	3 Months Ended
	Mar. 31, 2019
ACQUISITIONS [Abstract]
Estimated Fair Value of Assets Acquired and Liabilities Assumed	The following table summarizes the estimated fair value of the assets acquired and liabilities assumed after considering the measurement period adjustments described above: 2019 2018 (000s omitted) Wealth Resources Other (1) Consideration paid : Cash $ 1,200 $ 1,753 Total net consideration paid $ 1,200 $ 1,753 Recognized amounts of identifiable assets acquired and liabilities assumed: Cash and cash equivalents 0 16 Premises and equipment 0 10 Other assets 0 105 Other intangibles 1,200 1,343 Other liabilities 0 (31 ) Total identifiable assets, net 1,200 1,443 Goodwill $ 0 $ 310 (1)

INVESTMENT SECURITIES (Tables)

INVESTMENT SECURITIES (Tables)	3 Months Ended
	Mar. 31, 2019
INVESTMENT SECURITIES [Abstract]
Amortized Cost and Estimated Fair Value of Investment Securities	The amortized cost and estimated fair value of investment securities as of March 31, 2019 and December 31, 2018 are as follows: March 31, 2019 December 31, 2018 (000's omitted) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-Sale Portfolio: U.S. Treasury and agency securities $ 2,033,399 $ 6 , $ 5 , $ 2,034,972 $ 2,036 , $ 2 , $ 14,911 $ 2,023 , Obligations of state and political subdivisions 423 , 9,319 76 433 , 453 , 6 , 1,049 459 , Government agency mortgage-backed securities 389 , 2,587 5 , 386 , 390 , 1 , 9 , 382 , Corporate debt securities 2,572 0 19 2,553 2,588 0 42 2 , Government agency collateralized mortgage obligations 66 , 88 598 65 , 69 , 60 1,283 68 , Total available-for-sale portfolio $ 2 , , $ 18 , $ 11 , $ 2,922,943 $ 2 , , $ 10 , $ 26 , $ 2 , , Equity and other Securities: Equity securities, at fair value $ 251 $ 215 $ 2 $ 464 $ 251 $ 200 $ 19 $ 432 Federal Home Loan Bank common stock 6,308 0 0 6,308 8,768 0 0 8,768 Federal Reserve Bank common stock 30,690 0 0 30,690 30,690 0 0 30,690 Other equity securities, at adjusted cost 4 , 750 0 5,742 4 , 750 0 5,719 Total equity and other securities $ 42,241 $ 965 $ 2 $ 43,204 $ 44 , $ 950 $ 19 $ 45 ,
Summary of Investment Securities That Have Been in a Continuous Unrealized Loss Position for Less Than or Greater Than Twelve Months	A summary of investment securities that have been in a continuous unrealized loss position is as follows: As of March 31, 2019 Less than 12 Months 12 Months or Longer Total (000's omitted) # Fair Value Gross Unrealized Losses # Fair Value Gross Unrealized Losses # Fair Value Gross Unrealized Losses Available-for-Sale Portfolio: U.S. Treasury and agency securities 0 $ 0 $ 0 48 $ 862,482 $ 5,268 48 $ 862 , $ 5 , Obligations of state and political subdivisions 3 869 2 20 11,854 74 23 12 , 76 Government agency mortgage-backed securities 9 5 , 6 181 242 , 5 , 190 247 , 5 , Corporate debt securities 0 0 0 1 2,553 19 1 2,553 19 Government agency collateralized mortgage obligations 1 1 0 39 56,690 598 40 56 , 598 Total available-for-sale investment portfolio 13 $ 6,111 $ 8 289 $ 1,176 , $ 11 , 302 $ 1,182 , $ 11 , Equity and other Securities: Equity securities, at fair value 1 $ 98 $ 2 0 $ 0 $ 0 1 $ 98 $ 2 Total equity and other securities 1 $ 98 $ 2 0 $ 0 $ 0 1 $ 98 $ 2 As of December 31, 2018 Less than 12 Months 12 Months or Longer Total (000's omitted) # Fair Value Gross Unrealized Losses # Fair Value Gross Unrealized Losses # Fair Value Gross Unrealized Losses Available-for-Sale Portfolio: U.S. Treasury and agency securities 7 $ 473 , $ 682 64 $ 1,213,276 $ 14,229 71 $ 1,686 , $ 14,911 Obligations of state and political subdivisions 118 55 , 216 97 51,753 833 215 107 , 1,049 Government agency mortgage-backed securities 43 47,708 258 181 253 , 9 , 224 301 , 9 , Corporate debt securities 0 0 0 1 2,546 42 1 2,546 42 Government agency collateralized mortgage obligations 1 66 0 41 63,112 1,283 42 63 , 1,283 Total available-for-sale investment portfolio 169 $ 576 , $ 1 , 384 $ 1,584,618 $ 25 , 553 $ 2 , , $ 26 , Equity and other Securities: Equity securities, at fair value 1 $ 82 $ 19 0 $ 0 $ 0 1 $ 82 $ 19 Total equity and other securities 1 $ 82 $ 19 0 $ 0 $ 0 1 $ 82 $ 19
Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity	Securities not due at a single maturity date are shown separately. Available-for-Sale (000's omitted) Amortized Cost Fair Value Due in one year or less $ 76,873 $ 76,767 Due after one through five years 2,093,361 2,096,910 Due after five years through ten years 152,168 156,042 Due after ten years 137,485 140,965 Subtotal 2,459,887 2,470,684 Government agency mortgage-backed securities 389,154 386,543 Government agency collateralized mortgage obligations 66,226 65,716 Total $ 2,915,267 $ 2,922,943

LOANS (Tables)

LOANS (Tables)	3 Months Ended
	Mar. 31, 2019
Loans and Leases Receivable Disclosure [Line Items]
Loans Receivable, Net	The balances of these classes are summarized as follows: (000's omitted) March 31, 2019 December 31, 2018 Business lending $ 2,410,477 $ 2,396,977 Consumer mortgage 2,237,430 2,235,408 Consumer indirect 1,070,840 1,083,207 Consumer direct 173,042 178,820 Home equity 374,297 386,709 Gross loans, including deferred origination costs 6,266,086 6,281,121 Allowance for loan losses (49,107 ) (49,284 ) Loans, net of allowance for loan losses $ 6,216,979 $ 6,231,837
Accretable Discount Related to Credit Impaired Acquired Loans	The changes in the accretable discount related to the credit impaired acquired loans are as follows: (000’s omitted) Balance at December 31, 2018 $ 437 Accretion recognized, year-to-date (74 ) Balance at March 31, 2019 $ 363
Aged Analysis of Past Due Loans by Class	The following is an aged analysis of the Company’s past due loans, by class as of March 31, 2019: Legacy Loans (000’s omitted) Past Due 30 – 89 Days 90+ Days Past Due and Still Accruing Nonaccrual Total Past Due Current Total Loans Business lending $ 6,042 $ 68 $ 4,147 $ 10,257 $ 1,652,950 $ 1,663,207 Consumer mortgage 8,937 1,960 9,794 20,691 1,843,754 1,864,445 Consumer indirect 9,824 201 0 10,025 1,051,493 1,061,518 Consumer direct 985 41 0 1,026 169,334 170,360 Home equity 1,005 323 1,583 2,911 301,113 304,024 Total $ 26,793 $ 2,593 $ 15,524 $ 44,910 $ 5,018,644 $ 5,063,554 Acquired Loans (000’s omitted) Past Due 30 – 89 Days 90+ Days Past Due and Still Accruing Nonaccrual Total Past Due Acquired Impaired (1) Current Total Loans Business lending $ 2,526 $ 66 $ 3,254 $ 5,846 $ 5,342 $ 736,082 $ 747,270 Consumer mortgage 883 287 1,954 3,124 0 369,861 372,985 Consumer indirect 32 33 0 65 0 9,257 9,322 Consumer direct 33 25 0 58 0 2,624 2,682 Home equity 558 15 520 1,093 0 69,180 70,273 Total $ 4,032 $ 426 $ 5,728 $ 10,186 $ 5,342 $ 1,187,004 $ 1,202,532 (1) Acquired impaired loans were not classified as nonperforming assets as the loans are considered to be performing under ASC 310-30. As a result interest income, through the accretion of the difference between the carrying amount of the loans and the expected cashflows, is being recognized on all acquired impaired loans. The following is an aged analysis of the Company’s past due loans by class as of December 31, 2018: Legacy Loans (000’s omitted) Past Due 30 – 89 Days 90+ Days Past Due and Still Accruing Nonaccrual Total Past Due Current Total Loans Business lending $ 5,261 $ 179 $ 4,872 $ 10,312 $ 1,608,515 $ 1,618,827 Consumer mortgage 12,468 1,393 9,872 23,733 1,824,717 1,848,450 Consumer indirect 14,609 258 0 14,867 1,057,525 1,072,392 Consumer direct 1,778 48 0 1,826 173,948 175,774 Home equity 983 228 1,438 2,649 309,892 312,541 Total $ 35,099 $ 2,106 $ 16,182 $ 53,387 $ 4,974,597 $ 5,027,984 Acquired Loans (000’s omitted) Past Due 30 – 89 Days 90+ Days Past Due and Still Accruing Nonaccrual Total Past Due Acquired Impaired (1) Current Total Loans Business lending $ 974 $ 0 $ 3,498 $ 4,472 $ 5,446 $ 768,232 $ 778,150 Consumer mortgage 841 232 2,390 3,463 0 383,495 386,958 Consumer indirect 78 34 0 112 0 10,703 10,815 Consumer direct 115 4 0 119 0 2,927 3,046 Home equity 613 79 474 1,166 0 73,002 74,168 Total $ 2,621 $ 349 $ 6,362 $ 9,332 $ 5,446 $ 1,238,359 $ 1,253,137 (1) Acquired impaired loans were not classified as nonperforming assets as the loans are considered to be performing under ASC 310-30. As a result interest income, through the accretion of the difference between the carrying amount of the loans and the expected cashflows, is being recognized on all acquired impaired loans.
Non-Business Impaired Loans	A summary of individually evaluated impaired loans as of March 31, 2019 and December 31, 2018 follows: (000’s omitted) March 31, 2019 December 31, 2018 Loans with allowance allocation $ 0 $ 3,956 Loans without allowance allocation 5,118 2,230 Carrying balance 5,118 6,186 Contractual balance 12,052 12,078 Specifically allocated allowance 0 956
Troubled Debt Restructurings on Financing Receivables	Information regarding TDRs as of March 31, 2019 and December 31, 2018 is as follows: March 31, 2019 December 31, 2018 (000’s omitted) Nonaccrual Accruing Total Nonaccrual Accruing Total # Amount # Amount # Amount # Amount # Amount # Amount Business lending 3 $ 87 2 $ 161 5 $ 248 4 $ 162 2 $ 165 6 $ 327 Consumer mortgage 50 2,214 50 2,027 100 4,241 46 1,986 46 1,769 92 3,755 Consumer indirect 0 0 85 916 85 916 0 0 77 857 77 857 Consumer direct 0 0 15 1 15 1 0 0 22 71 22 71 Home equity 13 233 9 270 22 503 12 240 9 275 21 515 Total 66 $ 2,534 161 $ 3,375 227 $ 5,909 62 $ 2,388 156 $ 3,137 218 $ 5,525 The following table presents information related to loans modified in a TDR during the three months ended March 31, 2019 and 2018. Of the loans noted in the table below, all loans for the three months ended March 31, 2019 and 2018 were modified due to a Chapter 7 bankruptcy as described previously. The financial effects of these restructurings were immaterial Three Months Ended March 31, 2019 Three Months Ended March 31, 2018 (000’s omitted) Number of loans modified Outstanding Balance Number of loans modified Outstanding Balance Business lending 0 $ 0 1 $ 93 Consumer mortgage 8 665 0 0 Consumer indirect 11 98 4 41 Consumer direct 0 0 2 2 Home equity 1 4 0 0 Total 20 $ 767 7 $ 136
Allowance for Loan Losses by Class	The following presents by class the activity in the allowance for loan losses: Three Months Ended (000’s omitted) Business Lending Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Unallocated Acquired Impaired Total Beginning balance $ 18,522 $ 10,124 $ 14,366 $ 3,095 $ 2,144 $ 1,000 $ 33 $ 49,284 Charge-offs (1,216 ) (253 ) (1,823 ) (535 ) (74 ) 0 0 (3,901 ) Recoveries 134 22 962 179 5 0 0 1,302 Provision 831 424 746 317 (8 ) (10 ) 122 2,422 Ending balance $ 18,271 $ 10,317 $ 14,251 $ 3,056 $ 2,067 $ 990 $ 155 $ 49,107 Three Months Ended (000’s omitted) Business Lending Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Unallocated Acquired Impaired Total Beginning balance $ 17,257 $ 10,465 $ 13,468 $ 3,039 $ 2,107 $ 1,100 $ 147 $ 47,583 Charge-offs (1,669 ) (199 ) (2,284 ) (496 ) (56 ) 0 (43 ) (4,747 ) Recoveries 198 8 1,151 222 9 0 0 1,588 Provision 1,821 108 1,363 219 (20 ) (16 ) 204 3,679 Ending balance $ 17,607 $ 10,382 $ 13,698 $ 2,984 $ 2,040 $ 1,084 $ 308 $ 48,103
Business Lending [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans by Credit Quality Indicator	The following table shows the amount of business lending loans by credit quality category: March 31, 2019 December 31, 2018 (000’s omitted) Legacy Acquired Total Legacy Acquired Total Pass $ 1,475,145 $ 659,645 $ 2,134,790 $ 1,439,337 $ 702,493 $ 2,141,830 Special mention 108,129 53,562 161,691 105,065 40,107 145,172 Classified 79,933 28,721 108,654 74,425 28,525 102,950 Doubtful 0 0 0 0 1,579 1,579 Acquired impaired 0 5,342 5,342 0 5,446 5,446 Total $ 1,663,207 $ 747,270 $ 2,410,477 $ 1,618,827 $ 778,150 $ 2,396,977
All Other Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans by Credit Quality Indicator	The following table details the balances in all other loan categories at March 31, 2019: Legacy Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 1,852,691 $ 1,061,317 $ 170,319 $ 302,118 $ 3,386,445 Nonperforming 11,754 201 41 1,906 13,902 Total $ 1,864,445 $ 1,061,518 $ 170,360 $ 304,024 $ 3,400,347 Acquired Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 370,744 $ 9,289 $ 2,657 $ 69,738 $ 452,428 Nonperforming 2,241 33 25 535 2,834 Total $ 372,985 $ 9,322 $ 2,682 $ 70,273 $ 455,262 The following table details the balances in all other loan categories at December 31, 2018: Legacy Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 1,837,185 $ 1,072,134 $ 175,726 $ 310,875 $ 3,395,920 Nonperforming 11,265 258 48 1,666 13,237 Total $ 1,848,450 $ 1,072,392 $ 175,774 $ 312,541 $ 3,409,157 Acquired Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 384,336 $ 10,781 $ 3,042 $ 73,615 $ 471,774 Nonperforming 2,622 34 4 553 3,213 Total $ 386,958 $ 10,815 $ 3,046 $ 74,168 $ 474,987

GOODWILL AND IDENTIFIABLE INT_2

GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS (Tables)	3 Months Ended
	Mar. 31, 2019
GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS [Abstract]
Gross Carrying Amount and Accumulated Amortization of Identifiable Intangible Assets	The gross carrying amount and accumulated amortization for each type of identifiable intangible asset are as follows: March 31, 2019 December 31, 2018 (000's omitted) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Amortizing intangible assets: Core deposit intangibles $ 62,902 $ (45,789 ) $ 17,113 $ 62,902 $ (44 , ) $ 18 , Other intangibles 88,816 (35,013 ) 53,803 87 , (32 , ) 55 , Total amortizing intangibles $ 151,718 $ (80,802 ) $ 70,916 $ 150 , $ (76 , ) $ 73 ,
Estimated Aggregate Amortization Expense for Each of Five Succeeding Fiscal Years	The estimated aggregate amortization expense for each of the five succeeding fiscal years ended December 31 is as follows: (000's omitted) Apr - Dec 2019 $ 11,433 2020 12,956 2021 11,053 2022 9,483 2023 7,947 Thereafter 18,044 Total $ 70,916
Components of Goodwill	Shown below are the components of the Company’s goodwill at December 31, 2018 and March 31, 2019: (000’s omitted) December 31, 2018 Activity March 31, 2019 Goodwill $ 738,327 $ 0 $ 738,327 Accumulated impairment (4,824 ) 0 (4,824 ) Goodwill, net $ 733,503 $ 0 $ 733,503

LEASES (Tables)

LEASES (Tables)	3 Months Ended
	Mar. 31, 2019
LEASES [Abstract]
Components of Lease Expense	The components of lease expense are as follows: (000’s omitted) Three Months Ended March 31, 2019 Operating lease cost $ 2,117 Short-term lease cost (1) 54 Total lease cost $ 2,171 (1) Short-term lease cost includes the cost of leases with terms of twelve months or less, excluding leases with terms of one month or less.
Supplemental Cash Flow Information Related to Leases	Supplemental cash flow information related to leases is as follows: (000’s omitted) Three Months Ended March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash outflows for operating leases $ 2,030 Right-of-use assets obtained in exchange for lease obligations: Operating leases 2,969
Supplemental Balance Sheet Information Related to Leases	Supplemental balance sheet information related to leases is as follows: (000’s omitted, except lease term and discount rate) Three Months Ended March 31, 2019 Operating leases Operating lease right-of-use assets $ 34,956 Operating lease liabilities 35,630 Weighted average remaining lease term Operating leases 6.7 years Weighted average discount rate Operating leases 3.26 %
Operating Leases [Abstract]
Maturities of Lease Liabilities	Maturities of lease liabilities as of March 31, 2019 are as follows: (000’s omitted) Operating Leases Apr - Dec 2019 $ 6,534 2020 7,967 2021 6,396 2022 5,143 2023 3,393 Thereafter 10,653 Total lease payments 40,086 Less imputed interest (4,456 ) Total $ 35,630
706 North Clinton, LLC [Member]
Operating Leases [Abstract]
Maturities of Lease Liabilities	The maturities of the Company’s related party lease liabilities as of March 31, 2019 are as follows: (000’s omitted) 706 North Clinton, LLC Apr - Dec 2019 $ 443 2020 591 2021 591 2022 591 2023 591 Thereafter 3,538 Total lease payments 6,345 Less imputed interest (1,105 ) Total $ 5,240

MANDATORILY REDEEMABLE PREFER_2

MANDATORILY REDEEMABLE PREFERRED SECURITIES (Tables)	3 Months Ended
	Mar. 31, 2019
MANDATORILY REDEEMABLE PREFERRED SECURITIES [Abstract]
Terms of Preferred Securities	The terms of the preferred securities of each trust are as follows: Trust Issuance Date Par Amount Interest Rate Maturity Date Call Price CCT IV 12/8/2006 $75.0 million 3 month LIBOR plus 1.65% (4.26%) 12/15/2036 Par MBVT I 12/15/2004 $20.6 million 3 month LIBOR plus 1.95% (4.56%) 12/31/2034 Par

BENEFIT PLANS (Tables)

BENEFIT PLANS (Tables)	3 Months Ended
	Mar. 31, 2019
BENEFIT PLANS [Abstract]
Net Periodic Benefit Cost	The net periodic benefit cost for the three months ended March 31, 2019 and 2018 is as follows: Pension Benefits Post-retirement Benefits Three Months Ended March 31, Three Months Ended March 31, (000's omitted) 2019 2018 2019 2018 Service cost $ 1,270 $ 1,121 $ 0 $ 0 Interest cost 1,566 1,415 18 17 Expected return on plan assets (3,577 ) (3,705 ) 0 0 Amortization of unrecognized net loss 642 298 9 5 Amortization of prior service cost 16 (83 ) (45 ) (44 ) Net periodic benefit $ (83 ) $ (954 ) $ (18 ) $ (22 )

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2019
EARNINGS PER SHARE [Abstract]
Reconciliation of Basic to Diluted Earnings per Share	The following is a reconciliation of basic to diluted earnings per share for the three months ended March 31, 2019 and 2018: Three Months Ended March 31, (000's omitted, except per share data) 2019 2018 Net income $ 41,946 $ 40,106 Income attributable to unvested stock-based compensation awards (109 ) (141 ) Income available to common shareholders $ 41,837 $ 39,965 Weighted-average common shares outstanding – basic 51,520 50,934 Basic earnings per share $ 0.81 $ 0.78 Net income $ 41,946 $ 40,106 Income attributable to unvested stock-based compensation awards (109 ) (141 ) Income available to common shareholders $ 41,837 $ 39,965 Weighted-average common shares outstanding 51,520 50,934 Assumed exercise of stock options 541 563 Weighted-average common shares outstanding – diluted 52,061 51,497 Diluted earnings per share $ 0.80 $ 0.78

COMMITMENTS, CONTINGENT LIABI_2

COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS (Tables)	3 Months Ended
	Mar. 31, 2019
COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS [Abstract]
Off Balance Sheet Financial Instruments Contract Amounts	The contract amounts of commitments and contingencies are as follows: (000's omitted) March 31, 2019 December 31, 2018 Commitments to extend credit $ 1,047,047 $ 1,134 , Standby letters of credit 36,485 33 , Total $ 1,083,532 $ 1,167 ,

FAIR VALUE (Tables)

FAIR VALUE (Tables)	3 Months Ended
	Mar. 31, 2019
FAIR VALUE [Abstract]
Fair Value Measured on a Recurring Basis	The following tables set forth the Company’s financial assets and liabilities that were accounted for at fair value on a recurring basis. There were no transfers between any of the levels for the periods presented. March 31, 2019 (000's omitted) Level 1 Level 2 Level 3 Total Fair Value Available-for-sale investment securities: U.S. Treasury and agency securities $ 1,913,361 $ 121,611 $ 0 $ 2,034,972 Obligations of state and political subdivisions 0 433 , 0 433 , Government agency mortgage-backed securities 0 386 , 0 386 , Corporate debt securities 0 2,553 0 2,553 Government agency collateralized mortgage obligations 0 65 , 0 65 , Total available-for-sale investment securities 1,913,361 1,009,582 0 2,922,943 Equity securities 464 0 0 464 Mortgage loans held for sale 0 212 0 212 Commitments to originate real estate loans for sale 0 0 20 20 Forward sales commitments 0 (6 ) 0 (6 ) Interest rate swap agreements asset 0 835 0 835 Interest rate swap agreements liability 0 (705 ) 0 (705 ) Total $ 1,913,825 $ 1,009,918 $ 20 $ 2,923,763 December 31, 2018 (000's omitted) Level 1 Level 2 Level 3 Total Fair Value Available-for-sale investment securities: U.S. Treasury and agency securities $ 1,896,931 $ 126,822 $ 0 $ 2,023 , Obligations of state and political subdivisions 0 459,154 0 459 , Government agency mortgage-backed securities 0 382,477 0 382 , Corporate debt securities 0 2,546 0 2,546 Government agency collateralized mortgage obligations 0 68,119 0 68 , Total available-for-sale investment securities 1,896,931 1,039,118 0 2,936,049 Equity securities 432 0 0 432 Mortgage loans held for sale 0 83 0 83 Interest rate swap agreements asset 0 793 0 793 Interest rate swap agreements liability 0 (742 ) 0 (742 ) Total $ 1,897,363 $ 1,039,252 $ 0 $ 2,936,615
Assets and Liabilities Measured on a Non-Recurring Basis	The fair value information of assets and liabilities measured on a non-recurring basis presented below is not as of the period-end, but rather as of the date the fair value adjustment was recorded closest to the date presented. March 31, 2019 December 31, 2018 (000's omitted) Level 1 Level 2 Level 3 Total Fair Value Level 1 Level 2 Level 3 Total Fair Value Impaired loans $ 0 $ 0 $ 2,831 $ 2,831 $ 0 $ 0 $ 1,102 $ 1,102 Other real estate owned 0 0 1,524 1,524 0 0 1,320 1,320 Total $ 0 $ 0 $ 4,355 $ 4,355 $ 0 $ 0 $ 2,422 $ 2,422
Significant Unobservable Inputs, Fair Value Valuation Techniques	The significant unobservable inputs used in the determination of fair value of assets classified as Level 3 on a recurring or non-recurring basis are as follows: (000's omitted) Fair Value at March 31, 2019 Valuation Technique Significant Unobservable Inputs Significant Unobservable Input Range (Weighted Average) Impaired loans $ 2 , Fair value of collateral Estimated cost of disposal/market adjustment 9.0% - 40.4% (35 .0 %) Other real estate owned 1,524 Fair value of collateral Estimated cost of disposal/market adjustment 9.0% - 75.8% (23 . %) Commitments to originate real estate loans for sale 20 Discounted cash flow Embedded servicing value 1 % (000's omitted) Fair Value at December 31, 2018 Valuation Technique Significant Unobservable Inputs Significant Unobservable Input Range (Weighted Average) Impaired loans $ 1,102 Fair value of collateral Estimated cost of disposal/market adjustment 9.0% - 35 . %) Other real estate owned 1,320 Fair value of collateral Estimated cost of disposal/market adjustment 9.0% - 69 . . %)
Carrying Amounts and Estimated Fair Values of Other Financial Instruments	The carrying amounts and estimated fair values of the Company’s other financial instruments that are not accounted for at fair value at March 31, 2019 and December 31, 2018 are as follows: March 31, 2019 December 31, 2018 (000's omitted) Carrying Value Fair Value Carrying Value Fair Value Financial assets: Net loans $ 6,216,979 $ 6,266 , $ 6,231 , $ 6,247 , Financial liabilities: Deposits 8,619 , 8,607 , 8,322 , 8,308 , Short-term borrowings 0 0 54,4 00 54 , Securities sold under agreement to repurchase, short-term 249 , 249,880 259 , 259 , Other long-term debt 1 , 1,914 1 , 1 , Subordinated debt held by unconsolidated subsidiary trusts 97 , 97 , 97 , 97 ,

DERIVATIVE INSTRUMENTS (Tables)

DERIVATIVE INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2019
DERIVATIVE INSTRUMENTS [Abstract]
Amounts Related to Cumulative Basis Adjustments for Fair Value Hedges	As of March 31, 2019, the following amounts were recorded in the consolidated statement of condition related to cumulative basis adjustments for fair value hedges: (000’s omitted) Statement of Condition in Which the Hedged Item Is Included Carrying Amount of the Hedged Assets Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets March 31, 2019 March 31, 2019 Loans $ 7,006 $ (130 )
Fair Value of Derivative Instruments	Fair values of derivative instruments as of March 31, 2019 are as follows: (000’s omitted) March 31, 2019 Derivative Assets Derivative Liabilities Consolidated Statement of Condition Location Fair Value Consolidated Statement of Condition Location Fair Value Derivatives designated as hedging instruments under Subtopic 815-20 Interest rate swaps Other assets $ 130 Derivatives not designated as hedging instruments under Subtopic 815-20 Interest rate swaps Other assets 705 Accrued interest and other liabilities $ 705 Commitments to originate real estate loans for sale Other assets 20 Forward sales commitments Accrued interest and other liabilities 6 Total derivatives $ 855 $ 711

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2019
SEGMENT INFORMATION [Abstract]
Segment Reporting Information by Segment	Information about reportable segments and reconciliation of the information to the consolidated financial statements follows: (000's omitted) Banking Employee Benefit Services All Other Eliminations Consolidated Total Three Months Ended March 31, 2019 Net interest income $ 86,715 $ 108 $ 36 $ 0 $ 86,859 Provision for loan losses 2,422 0 0 0 2,422 Noninterest revenues 17,348 24,670 14,447 (769 ) 55,696 Amortization of intangible assets 1,483 1,769 878 0 4,130 Acquisition expenses 534 0 0 0 534 Other operating expenses 59,769 14,279 10,709 (769 ) 83,988 Income before income taxes $ 39,855 $ 8,730 $ 2,896 $ 0 $ 51,481 Assets $ 10,699,384 $ 199,345 $ 71,047 $ (53,309 ) $ 10,916,467 Goodwill $ 629,916 $ 83,275 $ 20,312 $ 0 $ 733,503 Core deposit intangibles & Other intangibles $ 17,113 $ 42,777 $ 11,026 $ 0 $ 70,916 Three Months Ended March 31, 2018 Net interest income $ 84,530 $ 70 $ 24 $ 0 $ 84,624 Provision for loan losses 3,679 0 0 0 3,679 Noninterest revenues 20,357 23,449 14,380 (695 ) 57,491 Amortization of intangible assets 1,744 2,088 966 0 4,798 Acquisition expenses (15 ) 7 0 0 (8 ) Other operating expenses 56,955 13,709 11,572 (695 ) 81,541 Income before income taxes $ 42,524 $ 7,715 $ 1,866 $ 0 $ 52,105 Assets $ 10,736,383 $ 205,544 $ 68,167 $ (43,539 ) $ 10,966,555 Goodwill $ 629,916 $ 83,275 $ 20,434 $ 0 $ 733,625 Core deposit intangibles & Other intangibles $ 23,281 $ 50,200 $ 13,478 $ 0 $ 86,959

ACQUISITIONS (Details)

ACQUISITIONS (Details) $ in Thousands	Jan. 22, 2019USD ($)CountyBranch	Jan. 02, 2019USD ($)	Apr. 02, 2018USD ($)	Jan. 02, 2018USD ($)	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)
Acquisitions [Abstract]
Cash					$ 1,200	$ 1,464
Goodwill					$ 733,503	$ 733,625	$ 733,503
Kinderhook Bank Corp [Member]
Acquisitions [Abstract]
Cash	$ 93,400
Number of branch locations added upon merger | Branch	11
Kinderhook Bank Corp [Member] | Upstate New York [Member]
Acquisitions [Abstract]
Number of counties where the bank has facilities | County	5
Wealth Resources Network, Inc [Member]
Acquisitions [Abstract]
Cash		$ 1,200
Goodwill		0
Wealth Resources Network, Inc [Member] | Customer Lists [Member]
Acquisitions [Abstract]
Intangibles		$ 1,200
HR Consultants (SA), LLC [Member]
Acquisitions [Abstract]
Cash			$ 300
HR Consultants (SA), LLC [Member] | Customer Lists [Member]
Acquisitions [Abstract]
Intangibles			$ 300
Penna & Associates Agency, Inc. [Member]
Acquisitions [Abstract]
Cash				$ 800
Goodwill				300
Penna & Associates Agency, Inc. [Member] | Customer Lists [Member]
Acquisitions [Abstract]
Intangibles				300
Styles Bridges Associates [Member]
Acquisitions [Abstract]
Cash				700
Styles Bridges Associates [Member] | Customer Lists [Member]
Acquisitions [Abstract]
Intangibles				$ 700

ACQUISITIONS, Estimated Fair Va

ACQUISITIONS, Estimated Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands		Jan. 02, 2019	Apr. 02, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Consideration paid [Abstract]
Cash				$ 1,200	$ 1,464
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Goodwill				$ 733,503	$ 733,625	$ 733,503
Wealth Resources Network, Inc [Member]
Consideration paid [Abstract]
Cash		$ 1,200
Total net consideration paid		1,200
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Cash and cash equivalents		0
Premises and equipment		0
Other assets		0
Other liabilities		0
Total identifiable assets, net		1,200
Goodwill		0
Wealth Resources Network, Inc [Member] | Other Intangibles [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Intangibles		$ 1,200
Other [Member]
Consideration paid [Abstract]
Cash	[1]		$ 1,753
Total net consideration paid	[1]		1,753
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Cash and cash equivalents	[1]		16
Premises and equipment	[1]		10
Other assets	[1]		105
Other liabilities	[1]		(31)
Total identifiable assets, net	[1]		1,443
Goodwill	[1]		310
Other [Member] | Other Intangibles [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Intangibles	[1]		$ 1,343
[1]	Includes amounts related to the Penna, Styles Bridges and HR Consultants acquisitions.

ACQUISITIONS, Intangible Asset,

ACQUISITIONS, Intangible Asset, Goodwill and Acquisition-related Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Summary of loans acquired [Abstract]
Merger and acquisition integration related (recoveries) expenses	$ 534	$ (8)
Wealth Resources Network, Inc [Member] | Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life	8 years
Styles Bridges Associates [Member] | Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life	8 years
Penna & Associates Agency, Inc. [Member] | Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life	8 years
HR Consultants (SA), LLC [Member] | Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life	8 years

ACCOUNTING POLICIES (Details)

ACCOUNTING POLICIES (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Contract Balances [Abstract]
Accounts receivable	$ 29,400	$ 26,400
Unbilled fee revenue	9,500	7,800
Unearned revenue	3,500	2,200
Recently Adopted Accounting Pronouncements [Abstract]
Right to use assets	34,956
Lease liability	$ 35,630
ASU 2016-02 [Member]
Recently Adopted Accounting Pronouncements [Abstract]
Right to use assets		34,200
Lease liability		$ 34,200

INVESTMENT SECURITIES, Availabl

INVESTMENT SECURITIES, Available-for-Sale Portfolio (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Available-for-Sale Portfolio [Abstract]
Amortized cost	$ 2,915,267	$ 2,952,278
Gross unrealized gains	18,835	10,339
Gross unrealized losses	11,159	26,568
Fair value	2,922,943	2,936,049
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized cost	2,915,267
Fair value	2,922,943
U.S. Treasury and Agency Securities [Member]
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized cost	2,033,399	2,036,474
Gross unrealized gains	6,841	2,190
Gross unrealized losses	5,268	14,911
Fair value	2,034,972	2,023,753
Obligations of State and Political Subdivisions [Member]
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized cost	423,916	453,640
Gross unrealized gains	9,319	6,563
Gross unrealized losses	76	1,049
Fair value	433,159	459,154
Government Agency Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized cost	389,154	390,234
Gross unrealized gains	2,587	1,526
Gross unrealized losses	5,198	9,283
Fair value	386,543	382,477
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized cost	2,572	2,588
Gross unrealized gains	0	0
Gross unrealized losses	19	42
Fair value	2,553	2,546
Government Agency Collateralized Mortgage Obligations [Member]
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized cost	66,226	69,342
Gross unrealized gains	88	60
Gross unrealized losses	598	1,283
Fair value	$ 65,716	$ 68,119

INVESTMENT SECURITIES, Equity a

INVESTMENT SECURITIES, Equity and Other Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Equity and Other Securities [Abstract]
Amortized cost	$ 42,241	$ 44,678
Gross unrealized gains	965	950
Gross unrealized losses	2	19
Fair value	43,204	45,609
Equity Securities, at Fair Value [Abstract]
Amortized cost	251	251
Gross unrealized gains	215	200
Gross unrealized losses	2	19
Fair value	464	432
Federal Home Loan Bank Common Stock [Member]
Other Equity Securities, at Adjusted Cost [Abstract]
Amortized cost	6,308	8,768
Fair value	6,308	8,768
Federal Reserve Bank Common Stock [Member]
Other Equity Securities, at Adjusted Cost [Abstract]
Amortized cost	30,690	30,690
Fair value	30,690	30,690
Other Equity Securities [Member]
Other Equity Securities, at Adjusted Cost [Abstract]
Amortized cost	4,992	4,969
Gross unrealized gains	750	750
Fair value	$ 5,742	$ 5,719

INVESTMENT SECURITIES, Investme

INVESTMENT SECURITIES, Investment Securities in a Continuous Unrealized Loss Position (Details) $ in Thousands	Mar. 31, 2019USD ($)Position	Dec. 31, 2018USD ($)Position
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	13	169
12 months or longer | Position	289	384
Total | Position	302	553
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 6,111	$ 576,527
12 months or longer	1,176,145	1,584,618
Total	1,182,256	2,161,145
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	8	1,156
12 months or longer	11,151	25,412
Total	$ 11,159	$ 26,568
Equity and Other Securities, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	1	1
12 months or longer | Position	0	0
Total | Position	1	1
Equity and Other Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 98	$ 82
12 months or longer	0	0
Total	98	82
Equity and Other Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses [Abstract]
Less than 12 months	2	19
12 months or longer	0	0
Total	$ 2	$ 19
U.S. Treasury and Agency Securities [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	0	7
12 months or longer | Position	48	64
Total | Position	48	71
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 0	$ 473,082
12 months or longer	862,482	1,213,276
Total	862,482	1,686,358
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	0	682
12 months or longer	5,268	14,229
Total	$ 5,268	$ 14,911
Obligations of State and Political Subdivisions [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	3	118
12 months or longer | Position	20	97
Total | Position	23	215
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 869	$ 55,671
12 months or longer	11,854	51,753
Total	12,723	107,424
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	2	216
12 months or longer	74	833
Total	$ 76	$ 1,049
Government Agency Mortgage-Backed Securities [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	9	43
12 months or longer | Position	181	181
Total | Position	190	224
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 5,241	$ 47,708
12 months or longer	242,566	253,931
Total	247,807	301,639
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	6	258
12 months or longer	5,192	9,025
Total	$ 5,198	$ 9,283
Corporate Debt Securities [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	0	0
12 months or longer | Position	1	1
Total | Position	1	1
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 0	$ 0
12 months or longer	2,553	2,546
Total	2,553	2,546
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	0	0
12 months or longer	19	42
Total	$ 19	$ 42
Government Agency Collateralized Mortgage Obligations [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	1	1
12 months or longer | Position	39	41
Total | Position	40	42
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 1	$ 66
12 months or longer	56,690	63,112
Total	56,691	63,178
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	0	0
12 months or longer	598	1,283
Total	$ 598	$ 1,283
Equity Securities, at Fair Value [Member]
Equity and Other Securities, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	1	1
12 months or longer | Position	0	0
Total | Position	1	1
Equity and Other Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 98	$ 82
12 months or longer	0	0
Total	98	82
Equity and Other Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses [Abstract]
Less than 12 months	2	19
12 months or longer	0	0
Total	$ 2	$ 19

INVESTMENT SECURITIES, Amortize

INVESTMENT SECURITIES, Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Available-for-Sale, Debt Maturities, Amortized Cost [Abstract]
Due in one year or less	$ 76,873
Due after one through five years	2,093,361
Due after five years through ten years	152,168
Due after ten years	137,485
Subtotal	2,459,887
Amortized cost	2,915,267
Available-for-Sale, Debt Maturities, Fair Value [Abstract]
Due in one year or less	76,767
Due after one through five years	2,096,910
Due after five years through ten years	156,042
Due after ten years	140,965
Subtotal	2,470,684
Fair value	2,922,943
Government Agency Mortgage-Backed Securities [Member]
Available-for-Sale, Debt Maturities, Amortized Cost [Abstract]
Without single maturity date	389,154
Amortized cost	389,154	$ 390,234
Available-for-Sale, Debt Maturities, Fair Value [Abstract]
Without single maturity date	386,543
Fair value	386,543	382,477
Government Agency Collateralized Mortgage Obligations [Member]
Available-for-Sale, Debt Maturities, Amortized Cost [Abstract]
Without single maturity date	66,226
Amortized cost	66,226	69,342
Available-for-Sale, Debt Maturities, Fair Value [Abstract]
Without single maturity date	65,716
Fair value	$ 65,716	$ 68,119

INVESTMENT SECURITIES, Invest_2

INVESTMENT SECURITIES, Investment Securities Pledged as Collateral (Details) $ in Millions	Mar. 31, 2019USD ($)
U.S. Treasury Securities [Member] | Securities Sold under Agreements to Repurchase [Member]
Investment Securities Pledged as Collateral [Abstract]
Investment securities pledged to collateralize certain deposits and borrowings	$ 263

LOANS, Loan Summary (Details)

LOANS, Loan Summary (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	$ 6,266,086	$ 6,281,121
Allowance for loan losses	(49,107)	(49,284)	$ (48,103)	$ (47,583)
Net loans	6,216,979	6,231,837
Credit impaired acquired loans, total balance due	7,300	7,400
Accretable discount related to credit impaired acquired loans [Roll forward]
Beginning Balance	437
Accretion recognized, year-to-date	(74)
Ending Balance	363
Business Lending [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	$ 2,410,477	2,396,977
Consumer Mortgage [Member] | Minimum [Member]
Loans receivable, net [Abstract]
Typical contract term	10 years
Consumer Mortgage [Member] | Maximum [Member]
Loans receivable, net [Abstract]
Typical contract term	30 years
Home Equity [Member] | Maximum [Member]
Loans receivable, net [Abstract]
Typical contract term	30 years
Commercial Portfolio Segment [Member] | Business Lending [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	$ 2,410,477	2,396,977
Commercial Portfolio Segment [Member] | Consumer Mortgage [Member]
Loans receivable, net [Abstract]
Allowance for loan losses	(10,317)	(10,124)	(10,382)	(10,465)
Residential Portfolio Segment [Member] | Business Lending [Member]
Loans receivable, net [Abstract]
Allowance for loan losses	(18,271)	(18,522)	(17,607)	(17,257)
Residential Portfolio Segment [Member] | Consumer Mortgage [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	2,237,430	2,235,408
Consumer Portfolio Segment [Member] | Consumer Indirect [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	1,070,840	1,083,207
Allowance for loan losses	(14,251)	(14,366)	(13,698)	(13,468)
Consumer Portfolio Segment [Member] | Consumer Direct [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	173,042	178,820
Allowance for loan losses	(3,056)	(3,095)	(2,984)	(3,039)
Consumer Portfolio Segment [Member] | Home Equity [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	374,297	386,709
Allowance for loan losses	$ (2,067)	$ (2,144)	$ (2,040)	$ (2,107)

LOANS, Credit Quality By Past D

LOANS, Credit Quality By Past Due Status (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Aged analysis of the company's loans [Abstract]
Total loans		$ 6,266,086	$ 6,281,121
Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		2,593	2,106
Nonaccrual		15,524	16,182
Total past due		44,910	53,387
Current		5,018,644	4,974,597
Total loans		5,063,554	5,027,984
Legacy Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		26,793	35,099
Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		426	349
Nonaccrual		5,728	6,362
Total past due		10,186	9,332
Acquired impaired	[1]	5,342	5,446
Current		1,187,004	1,238,359
Total loans		1,202,532	1,253,137
Acquired Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		4,032	2,621
Business Lending [Member]
Aged analysis of the company's loans [Abstract]
Total loans		2,410,477	2,396,977
Business Lending [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		1,663,207	1,618,827
Business Lending [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		747,270	778,150
Consumer Mortgage [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		1,864,445	1,848,450
Consumer Mortgage [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		372,985	386,958
Consumer Indirect [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		1,061,518	1,072,392
Consumer Indirect [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		9,322	10,815
Consumer Direct [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		170,360	175,774
Consumer Direct [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		2,682	3,046
Home Equity [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		304,024	312,541
Home Equity [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		70,273	74,168
Commercial Portfolio Segment [Member] | Business Lending [Member]
Aged analysis of the company's loans [Abstract]
Total loans		2,410,477	2,396,977
Commercial Portfolio Segment [Member] | Business Lending [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		68	179
Nonaccrual		4,147	4,872
Total past due		10,257	10,312
Current		1,652,950	1,608,515
Total loans		1,663,207	1,618,827
Commercial Portfolio Segment [Member] | Business Lending [Member] | Legacy Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		6,042	5,261
Commercial Portfolio Segment [Member] | Business Lending [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		66	0
Nonaccrual		3,254	3,498
Total past due		5,846	4,472
Acquired impaired	[1]	5,342	5,446
Current		736,082	768,232
Total loans		747,270	778,150
Commercial Portfolio Segment [Member] | Business Lending [Member] | Acquired Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		2,526	974
Residential Portfolio Segment [Member] | Consumer Mortgage [Member]
Aged analysis of the company's loans [Abstract]
Total loans		2,237,430	2,235,408
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		1,960	1,393
Nonaccrual		9,794	9,872
Total past due		20,691	23,733
Current		1,843,754	1,824,717
Total loans		1,864,445	1,848,450
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] | Legacy Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		8,937	12,468
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		287	232
Nonaccrual		1,954	2,390
Total past due		3,124	3,463
Acquired impaired	[1]	0	0
Current		369,861	383,495
Total loans		372,985	386,958
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] | Acquired Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		883	841
Consumer Portfolio Segment [Member] | Consumer Indirect [Member]
Aged analysis of the company's loans [Abstract]
Total loans		1,070,840	1,083,207
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		201	258
Nonaccrual		0	0
Total past due		10,025	14,867
Current		1,051,493	1,057,525
Total loans		1,061,518	1,072,392
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] | Legacy Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		9,824	14,609
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		33	34
Nonaccrual		0	0
Total past due		65	112
Acquired impaired	[1]	0	0
Current		9,257	10,703
Total loans		9,322	10,815
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] | Acquired Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		32	78
Consumer Portfolio Segment [Member] | Consumer Direct [Member]
Aged analysis of the company's loans [Abstract]
Total loans		173,042	178,820
Consumer Portfolio Segment [Member] | Consumer Direct [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		41	48
Nonaccrual		0	0
Total past due		1,026	1,826
Current		169,334	173,948
Total loans		170,360	175,774
Consumer Portfolio Segment [Member] | Consumer Direct [Member] | Legacy Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		985	1,778
Consumer Portfolio Segment [Member] | Consumer Direct [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		25	4
Nonaccrual		0	0
Total past due		58	119
Acquired impaired	[1]	0	0
Current		2,624	2,927
Total loans		2,682	3,046
Consumer Portfolio Segment [Member] | Consumer Direct [Member] | Acquired Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		33	115
Consumer Portfolio Segment [Member] | Home Equity [Member]
Aged analysis of the company's loans [Abstract]
Total loans		374,297	386,709
Consumer Portfolio Segment [Member] | Home Equity [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		323	228
Nonaccrual		1,583	1,438
Total past due		2,911	2,649
Current		301,113	309,892
Total loans		304,024	312,541
Consumer Portfolio Segment [Member] | Home Equity [Member] | Legacy Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		1,005	983
Consumer Portfolio Segment [Member] | Home Equity [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		15	79
Nonaccrual		520	474
Total past due		1,093	1,166
Acquired impaired	[1]	0	0
Current		69,180	73,002
Total loans		70,273	74,168
Consumer Portfolio Segment [Member] | Home Equity [Member] | Acquired Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		$ 558	$ 613
[1]	Acquired impaired loans were not classified as nonperforming assets as the loans are considered to be performing under ASC 310-30. As a result interest income, through the accretion of the difference between the carrying amount of the loans and the expected cashflows, is being recognized on all acquired impaired loans.

LOANS, Amount of Business Lendi

LOANS, Amount of Business Lending Loans by Credit Quality Category (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Business Lending Loans by Credit Quality Category [Abstract]
Loans	$ 6,266,086	$ 6,281,121
Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	5,063,554	5,027,984
Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	1,202,532	1,253,137
Business Lending [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	2,410,477	2,396,977
Business Lending [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	1,663,207	1,618,827
Business Lending [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	747,270	778,150
Business Lending [Member] | Pass [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	2,134,790	2,141,830
Business Lending [Member] | Pass [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	1,475,145	1,439,337
Business Lending [Member] | Pass [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	659,645	702,493
Business Lending [Member] | Special Mention [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	161,691	145,172
Business Lending [Member] | Special Mention [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	108,129	105,065
Business Lending [Member] | Special Mention [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	53,562	40,107
Business Lending [Member] | Classified [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	108,654	102,950
Business Lending [Member] | Classified [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	79,933	74,425
Business Lending [Member] | Classified [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	28,721	28,525
Business Lending [Member] | Doubtful [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	0	1,579
Business Lending [Member] | Doubtful [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	0	0
Business Lending [Member] | Doubtful [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	0	1,579
Business Lending [Member] | Acquired Impaired [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	5,342	5,446
Business Lending [Member] | Acquired Impaired [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	0	0
Business Lending [Member] | Acquired Impaired [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	5,342	5,446
All Other Loans [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	3,400,347	3,409,157
All Other Loans [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	455,262	474,987
All Other Loans [Member] | Performing [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	3,386,445	3,395,920
All Other Loans [Member] | Performing [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	452,428	471,774
All Other Loans [Member] | Nonperforming [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	13,902	13,237
All Other Loans [Member] | Nonperforming [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	2,834	3,213
Consumer Mortgage [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	1,864,445	1,848,450
Consumer Mortgage [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	372,985	386,958
Consumer Mortgage [Member] | Performing [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	1,852,691	1,837,185
Consumer Mortgage [Member] | Performing [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	370,744	384,336
Consumer Mortgage [Member] | Nonperforming [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	11,754	11,265
Consumer Mortgage [Member] | Nonperforming [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	2,241	2,622
Consumer Indirect [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	1,061,518	1,072,392
Consumer Indirect [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	9,322	10,815
Consumer Indirect [Member] | Performing [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	1,061,317	1,072,134
Consumer Indirect [Member] | Performing [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	9,289	10,781
Consumer Indirect [Member] | Nonperforming [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	201	258
Consumer Indirect [Member] | Nonperforming [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	33	34
Consumer Direct [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	170,360	175,774
Consumer Direct [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	2,682	3,046
Consumer Direct [Member] | Performing [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	170,319	175,726
Consumer Direct [Member] | Performing [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	2,657	3,042
Consumer Direct [Member] | Nonperforming [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	41	48
Consumer Direct [Member] | Nonperforming [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	25	4
Home Equity [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	304,024	312,541
Home Equity [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	70,273	74,168
Home Equity [Member] | Performing [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	302,118	310,875
Home Equity [Member] | Performing [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	69,738	73,615
Home Equity [Member] | Nonperforming [Member] | Legacy Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	1,906	1,666
Home Equity [Member] | Nonperforming [Member] | Acquired Loans [Member]
Business Lending Loans by Credit Quality Category [Abstract]
Loans	$ 535	$ 553

LOANS, Summary of Impaired Loan

LOANS, Summary of Impaired Loans, Excluding Purchased Impaired (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Impaired loans [Abstract]
Loans with allowance allocation	$ 0	$ 3,956
Loans without allowance allocation	5,118	2,230
Carrying balance	5,118	6,186
Contractual balance	12,052	12,078
Specifically allocated allowance	$ 0	$ 956

LOANS, Troubled Debt Restructur

LOANS, Troubled Debt Restructurings (TDRs) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)Loan	Mar. 31, 2018USD ($)Loan	Dec. 31, 2018USD ($)Loan
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	227		218
TDRs, amount	$ 5,909		$ 5,525
Loans modified in TDR during the year, number | Loan	20	7
Loans modified in TDR during the year, amount	$ 767	$ 136
Maximum [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
Threshold balance of TDR loans collectively included in general loan loss allocation and qualitative review	$ 500
Nonaccrual [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	66		62
TDRs, amount	$ 2,534		$ 2,388
Accruing [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	161		156
TDRs, amount	$ 3,375		$ 3,137
Commercial Portfolio Segment [Member] | Minimum [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
Threshold balance of loans individually evaluated for impairment	$ 500
Commercial Portfolio Segment [Member] | Business Lending [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	5		6
TDRs, amount	$ 248		$ 327
Loans modified in TDR during the year, number | Loan	0	1
Loans modified in TDR during the year, amount	$ 0	$ 93
Commercial Portfolio Segment [Member] | Business Lending [Member] | Nonaccrual [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	3		4
TDRs, amount	$ 87		$ 162
Commercial Portfolio Segment [Member] | Business Lending [Member] | Accruing [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	2		2
TDRs, amount	$ 161		$ 165
Residential Portfolio Segment [Member] | Consumer Mortgage [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	100		92
TDRs, amount	$ 4,241		$ 3,755
Loans modified in TDR during the year, number | Loan	8	0
Loans modified in TDR during the year, amount	$ 665	$ 0
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] | Nonaccrual [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	50		46
TDRs, amount	$ 2,214		$ 1,986
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] | Accruing [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	50		46
TDRs, amount	$ 2,027		$ 1,769
Consumer Portfolio Segment [Member] | Consumer Indirect [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	85		77
TDRs, amount	$ 916		$ 857
Loans modified in TDR during the year, number | Loan	11	4
Loans modified in TDR during the year, amount	$ 98	$ 41
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] | Nonaccrual [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	0		0
TDRs, amount	$ 0		$ 0
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] | Accruing [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	85		77
TDRs, amount	$ 916		$ 857
Consumer Portfolio Segment [Member] | Consumer Direct [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	15		22
TDRs, amount	$ 1		$ 71
Loans modified in TDR during the year, number | Loan	0	2
Loans modified in TDR during the year, amount	$ 0	$ 2
Consumer Portfolio Segment [Member] | Consumer Direct [Member] | Nonaccrual [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	0		0
TDRs, amount	$ 0		$ 0
Consumer Portfolio Segment [Member] | Consumer Direct [Member] | Accruing [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	15		22
TDRs, amount	$ 1		$ 71
Consumer Portfolio Segment [Member] | Home Equity [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	22		21
TDRs, amount	$ 503		$ 515
Loans modified in TDR during the year, number | Loan	1	0
Loans modified in TDR during the year, amount	$ 4	$ 0
Consumer Portfolio Segment [Member] | Home Equity [Member] | Nonaccrual [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	13		12
TDRs, amount	$ 233		$ 240
Consumer Portfolio Segment [Member] | Home Equity [Member] | Accruing [Member]
Troubled Debt Restructurings (TDRs) [Abstract]
TDRs, number | Loan	9		9
TDRs, amount	$ 270		$ 275

LOANS, Allowance for Loan Losse

LOANS, Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Allowance for loan losses [Roll Forward]
Beginning balance	$ 49,284	$ 47,583
Charge-offs	(3,901)	(4,747)
Recoveries	1,302	1,588
Provision	2,422	3,679
Ending balance	49,107	48,103
Acquired Impaired [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	33	147
Charge-offs	0	(43)
Recoveries	0	0
Provision	122	204
Ending balance	155	308
Residential Portfolio Segment [Member] | Business Lending [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	18,522	17,257
Charge-offs	(1,216)	(1,669)
Recoveries	134	198
Provision	831	1,821
Ending balance	18,271	17,607
Commercial Portfolio Segment [Member] | Consumer Mortgage [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	10,124	10,465
Charge-offs	(253)	(199)
Recoveries	22	8
Provision	424	108
Ending balance	10,317	10,382
Consumer Portfolio Segment [Member] | Consumer Indirect [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	14,366	13,468
Charge-offs	(1,823)	(2,284)
Recoveries	962	1,151
Provision	746	1,363
Ending balance	14,251	13,698
Consumer Portfolio Segment [Member] | Consumer Direct [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	3,095	3,039
Charge-offs	(535)	(496)
Recoveries	179	222
Provision	317	219
Ending balance	3,056	2,984
Consumer Portfolio Segment [Member] | Home Equity [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	2,144	2,107
Charge-offs	(74)	(56)
Recoveries	5	9
Provision	(8)	(20)
Ending balance	2,067	2,040
Unallocated Financing Receivables [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	1,000	1,100
Charge-offs	0	0
Recoveries	0	0
Provision	(10)	(16)
Ending balance	$ 990	$ 1,084

GOODWILL AND IDENTIFIABLE INT_3

GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Identifiable Intangible Assets [Abstract]
Gross carrying amount	$ 151,718	$ 150,518
Accumulated amortization	(80,802)	(76,672)
Net carrying amount	70,916	73,846
Estimated aggregate amortization expense for each of five succeeding fiscal years [Abstract]
Apr - Dec 2019	11,433
2020	12,956
2021	11,053
2022	9,483
2023	7,947
Thereafter	18,044
Net carrying amount	70,916	73,846
Components of goodwill [Abstract]
Goodwill, beginning of period	738,327
Goodwill, activity	0
Goodwill, end of period	738,327
Accumulated impairment, beginning of period	(4,824)
Accumulated impairment, activity	0
Accumulated impairment, end of period	(4,824)
Goodwill, net, beginning of period	733,503
Goodwill, net, activity	0
Goodwill, net, end of period	733,503
Core Deposit Intangibles [Member]
Identifiable Intangible Assets [Abstract]
Gross carrying amount	62,902	62,902
Accumulated amortization	(45,789)	(44,306)
Net carrying amount	17,113	18,596
Estimated aggregate amortization expense for each of five succeeding fiscal years [Abstract]
Net carrying amount	17,113	18,596
Other Intangibles [Member]
Identifiable Intangible Assets [Abstract]
Gross carrying amount	88,816	87,616
Accumulated amortization	(35,013)	(32,366)
Net carrying amount	53,803	55,250
Estimated aggregate amortization expense for each of five succeeding fiscal years [Abstract]
Net carrying amount	$ 53,803	$ 55,250

LEASES (Details)

LEASES (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Operating Leases [Abstract]
Term of option to terminate	1 year
Components of Lease Expense [Abstract]
Operating lease cost	$ 2,117
Short-term lease cost	54	[1]
Total lease cost	2,171
Cash paid for amounts included in the measurement of lease liabilities [Abstract]
Operating cash outflows for operating leases	2,030
Right-of-use assets obtained in exchange for lease obligations [Abstract]
Operating leases	2,969
Operating leases [Abstract]
Operating lease right-of-use assets	34,956
Operating lease liabilities	$ 35,630
Weighted average remaining lease term [Abstract]
Operating leases	6 years 8 months 12 days
Weighted average discount rate [Abstract]
Operating leases	3.26%
Maturities of Lease Liabilities [Abstract]
Apr - Dec 2019	$ 6,534
2020	7,967
2021	6,396
2022	5,143
2023	3,393
Thereafter	10,653
Total lease payments	40,086
Less imputed interest	(4,456)
Total	$ 35,630
Minimum [Member]
Operating Leases [Abstract]
Remaining term of lease	1 year
Term of option to extend	1 year
Maximum [Member]
Operating Leases [Abstract]
Remaining term of lease	16 years
Term of option to extend	40 years
706 North Clinton, LLC [Member]
Operating leases [Abstract]
Operating lease right-of-use assets	$ 5,200
Operating lease liabilities	$ 5,240
Weighted average remaining lease term [Abstract]
Operating leases	10 years 8 months 12 days
Weighted average discount rate [Abstract]
Operating leases	3.67%
Maturities of Lease Liabilities [Abstract]
Apr - Dec 2019	$ 443
2020	591
2021	591
2022	591
2023	591
Thereafter	3,538
Total lease payments	6,345
Less imputed interest	(1,105)
Total	$ 5,240
Membership interest	50.00%
[1]	Short-term lease cost includes the cost of leases with terms of twelve months or less, excluding leases with terms of one month or less.

MANDATORILY REDEEMABLE PREFER_3

MANDATORILY REDEEMABLE PREFERRED SECURITIES (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)Trust
Mandatorily Redeemable Preferred Securities [Abstract]
Number of unconsolidated subsidiary business trusts owned | Trust	2
Business Trusts [Member]
Mandatorily Redeemable Preferred Securities [Abstract]
Percent ownership of unconsolidated subsidiary trusts	100.00%
Preferred Debt [Member] | Community Capital Trust IV [Member]
Terms of preferred securities for each trust [Abstract]
Issuance date	Dec. 8, 2006
Par amount	$ 75
Variable interest rate basis	3 month LIBOR
Effective interest rate	4.26%
Maturity date	Dec. 15, 2036
Call price	Par
Preferred Debt [Member] | Community Capital Trust IV [Member] | LIBOR [Member]
Terms of preferred securities for each trust [Abstract]
Term of variable rate	3 months
Variable interest rate, basis spread	1.65%
Preferred Debt [Member] | MBVT Statutory Trust I [Member]
Terms of preferred securities for each trust [Abstract]
Issuance date	Dec. 15, 2004
Par amount	$ 20.6
Variable interest rate basis	3 month LIBOR
Effective interest rate	4.56%
Maturity date	Dec. 31, 2034
Call price	Par
Preferred Debt [Member] | MBVT Statutory Trust I [Member] | LIBOR [Member]
Terms of preferred securities for each trust [Abstract]
Term of variable rate	3 months
Variable interest rate, basis spread	1.95%

BENEFIT PLANS (Details)

BENEFIT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost	$ 1,270	$ 1,121
Interest cost	1,566	1,415
Expected return on plan assets	(3,577)	(3,705)
Amortization of unrecognized net loss	642	298
Amortization of prior service cost	16	(83)
Net periodic benefit	(83)	(954)
Pension Benefits [Member] | Nonqualified Plan [Member] | Unfunded Plan [Member]
Pension Plans [Abstract]
Unfunded initial projected benefit obligation	800
Contribution made to defined benefit pension plan by employer	7,300
Post-retirement Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost	0	0
Interest cost	18	17
Expected return on plan assets	0	0
Amortization of unrecognized net loss	9	5
Amortization of prior service cost	(45)	(44)
Net periodic benefit	$ (18)	$ (22)

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
EARNINGS PER SHARE [Abstract]
Weighted-average anti-dilutive stock options outstanding (in shares)	500,000	400,000
Basic earnings per share [Abstract]
Net income	$ 41,946	$ 40,106
Income attributable to unvested stock-based compensation awards	(109)	(141)
Income available to common shareholders	$ 41,837	$ 39,965
Weighted-average common shares outstanding - basic (in shares)	51,520,000	50,934,000
Basic earnings per share (in dollars per share)	$ 0.81	$ 0.78
Diluted earnings per share [Abstract]
Net income	$ 41,946	$ 40,106
Income attributable to unvested stock-based compensation awards	(109)	(141)
Income available to common shareholders	$ 41,837	$ 39,965
Weighted-average common shares outstanding - basic (in shares)	51,520,000	50,934,000
Assumed exercise of stock options (in shares)	541,000	563,000
Weighted-average common shares outstanding - diluted (in shares)	52,061,000	51,497,000
Diluted earnings per share (in dollars per share)	$ 0.80	$ 0.78
Stock Repurchase Program [Abstract]
Number of common shares authorized to be repurchased (in shares)			2,500,000	2,500,000
Number of common shares repurchased (in shares)	0	0

COMMITMENTS, CONTINGENT LIABI_3

COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Commitments, Contingent Liabilities and Restrictions [Abstract]
Contract amount of commitments and contingencies	$ 1,083,532	$ 1,167,745
Minimum [Member]
Commitments, Contingent Liabilities and Restrictions [Abstract]
Range of reasonably possible losses for such matters in the aggregate, beyond the existing recorded liability	0
Maximum [Member]
Commitments, Contingent Liabilities and Restrictions [Abstract]
Range of reasonably possible losses for such matters in the aggregate, beyond the existing recorded liability	1,000
Commitments to Extend Credit [Member]
Commitments, Contingent Liabilities and Restrictions [Abstract]
Contract amount of commitments and contingencies	1,047,047	1,134,576
Standby Letters of Credit [Member]
Commitments, Contingent Liabilities and Restrictions [Abstract]
Contract amount of commitments and contingencies	$ 36,485	$ 33,169

FAIR VALUE, Financial Assets an

FAIR VALUE, Financial Assets and Liabilities Accounted for at Fair Value On a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	$ 2,922,943
Equity securities	464	$ 432
Commitments to Originate Real Estate Loans for Sale [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	20
U.S. Treasury and Agency Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	2,034,972	2,023,753
Obligations of State and Political Subdivisions [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	433,159	459,154
Government Agency Mortgage-Backed Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	386,543	382,477
Corporate Debt Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	2,553	2,546
Government Agency Collateralized Mortgage Obligations [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	65,716	68,119
Recurring [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	2,922,943	2,936,049
Equity securities	464	432
Mortgage loans held for sale	212	83
Total	2,923,763	2,936,615
Recurring [Member] | Commitments to Originate Real Estate Loans for Sale [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	20
Recurring [Member] | Forward Sales Commitments [Member]
Available-for-sale investment securities [Abstract]
Derivative liability	(6)
Recurring [Member] | Interest Rate Swap Agreements [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	835	793
Derivative liability	(705)	(742)
Recurring [Member] | U.S. Treasury and Agency Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	2,034,972	2,023,753
Recurring [Member] | Obligations of State and Political Subdivisions [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	433,159	459,154
Recurring [Member] | Government Agency Mortgage-Backed Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	386,543	382,477
Recurring [Member] | Corporate Debt Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	2,553	2,546
Recurring [Member] | Government Agency Collateralized Mortgage Obligations [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	65,716	68,119
Recurring [Member] | Level 1 [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	1,913,361	1,896,931
Equity securities	464	432
Mortgage loans held for sale	0	0
Total	1,913,825	1,897,363
Recurring [Member] | Level 1 [Member] | Commitments to Originate Real Estate Loans for Sale [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	0
Recurring [Member] | Level 1 [Member] | Forward Sales Commitments [Member]
Available-for-sale investment securities [Abstract]
Derivative liability	0
Recurring [Member] | Level 1 [Member] | Interest Rate Swap Agreements [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	0	0
Derivative liability	0	0
Recurring [Member] | Level 1 [Member] | U.S. Treasury and Agency Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	1,913,361	1,896,931
Recurring [Member] | Level 1 [Member] | Obligations of State and Political Subdivisions [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	0	0
Recurring [Member] | Level 1 [Member] | Government Agency Mortgage-Backed Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	0	0
Recurring [Member] | Level 1 [Member] | Corporate Debt Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	0	0
Recurring [Member] | Level 1 [Member] | Government Agency Collateralized Mortgage Obligations [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	0	0
Recurring [Member] | Level 2 [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	1,009,582	1,039,118
Equity securities	0	0
Mortgage loans held for sale	212	83
Total	1,009,918	1,039,252
Mortgage loans held for sale, at principal value	200	100
Recurring [Member] | Level 2 [Member] | Commitments to Originate Real Estate Loans for Sale [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	0
Recurring [Member] | Level 2 [Member] | Forward Sales Commitments [Member]
Available-for-sale investment securities [Abstract]
Derivative liability	(6)
Recurring [Member] | Level 2 [Member] | Interest Rate Swap Agreements [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	835	793
Derivative liability	(705)	(742)
Recurring [Member] | Level 2 [Member] | U.S. Treasury and Agency Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	121,611	126,822
Recurring [Member] | Level 2 [Member] | Obligations of State and Political Subdivisions [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	433,159	459,154
Recurring [Member] | Level 2 [Member] | Government Agency Mortgage-Backed Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	386,543	382,477
Recurring [Member] | Level 2 [Member] | Corporate Debt Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	2,553	2,546
Recurring [Member] | Level 2 [Member] | Government Agency Collateralized Mortgage Obligations [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	65,716	68,119
Recurring [Member] | Level 3 [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	0	0
Equity securities	0	0
Mortgage loans held for sale	0	0
Total	20	0
Recurring [Member] | Level 3 [Member] | Commitments to Originate Real Estate Loans for Sale [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	20
Recurring [Member] | Level 3 [Member] | Forward Sales Commitments [Member]
Available-for-sale investment securities [Abstract]
Derivative liability	0
Recurring [Member] | Level 3 [Member] | Interest Rate Swap Agreements [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	0	0
Derivative liability	0	0
Recurring [Member] | Level 3 [Member] | U.S. Treasury and Agency Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	0	0
Recurring [Member] | Level 3 [Member] | Obligations of State and Political Subdivisions [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	0	0
Recurring [Member] | Level 3 [Member] | Government Agency Mortgage-Backed Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	0	0
Recurring [Member] | Level 3 [Member] | Corporate Debt Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	0	0
Recurring [Member] | Level 3 [Member] | Government Agency Collateralized Mortgage Obligations [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	$ 0	$ 0

FAIR VALUE, Assets and Liabilit

FAIR VALUE, Assets and Liabilities Measured on Nonrecurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Impaired loans	$ 2,831	$ 1,102
Other real estate owned	1,524	1,320
Valuation allowance	0	956
Mortgage Servicing Rights [Member]
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Valuation allowance	0
Non-recurring [Member]
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Impaired loans	2,831	1,102
Other real estate owned	1,524	1,320
Total	4,355	2,422
Non-recurring [Member] | Level 1 [Member]
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Impaired loans	0	0
Other real estate owned	0	0
Total	0	0
Non-recurring [Member] | Level 2 [Member]
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Impaired loans	0	0
Other real estate owned	0	0
Total	0	0
Non-recurring [Member] | Level 3 [Member]
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Impaired loans	2,831	1,102
Other real estate owned	1,524	1,320
Total	$ 4,355	$ 2,422

FAIR VALUE, Significant Unobser

FAIR VALUE, Significant Unobservable Inputs (Details) $ in Thousands	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3 [Abstract]
Impaired loans	$ 2,831	$ 1,102
Other real estate owned	$ 1,524	$ 1,320
Other real estate owned, Valuation Technique [Extensible List]	us-gaap:MarketApproachValuationTechniqueMember	us-gaap:MarketApproachValuationTechniqueMember
Other real estate owned, Measurement Input [Extensible List]	us-gaap:MeasurementInputCostToSellMember	us-gaap:MeasurementInputCostToSellMember
Minimum [Member]
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3 [Abstract]
Other real estate owned, measurement input	0.090	0.090
Minimum [Member] | Fair Value of Collateral [Member] | Estimated Cost of Disposal/Market Adjustment [Member]
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3 [Abstract]
Impaired loans, measurement input	0.090	0.090
Maximum [Member]
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3 [Abstract]
Other real estate owned, measurement input	0.758	0.693
Maximum [Member] | Fair Value of Collateral [Member] | Estimated Cost of Disposal/Market Adjustment [Member]
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3 [Abstract]
Impaired loans, measurement input	0.404	0.354
Weighted Average [Member]
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3 [Abstract]
Other real estate owned, measurement input	0.238	0.238
Weighted Average [Member] | Fair Value of Collateral [Member] | Estimated Cost of Disposal/Market Adjustment [Member]
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3 [Abstract]
Impaired loans, measurement input	0.350	0.288
Commitments to Originate Real Estate Loans for Sale [Member]
Significant Unobservable Inputs used in determination of Fair Value of Assets Classified as Level 3 [Abstract]
Commitments to originate real estate loans for sale	$ 20
Commitments to originate real estate loans for sale, Valuation Technique [Extensible List]	us-gaap:ValuationTechniqueDiscountedCashFlowMember
Commitments to originate real estate loans for sale, Measurement Input [Extensible List]	cbu:MeasurementInputEmbeddedServicingValueMember
Commitments to originate real estate loans for sale, measurement input	0.01

FAIR VALUE, Carrying Amounts an

FAIR VALUE, Carrying Amounts and Estimated Fair Values of Other Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Carrying Value [Member]
Financial assets [Abstract]
Net loans	$ 6,216,979	$ 6,231,837
Financial liabilities [Abstract]
Deposits	8,619,662	8,322,371
Short-term borrowings	0	54,400
Securities sold under agreement to repurchase, short-term	249,880	259,367
Other long-term debt	1,953	1,976
Subordinated debt held by unconsolidated subsidiary trusts	97,939	97,939
Fair Value [Member]
Financial assets [Abstract]
Net loans	6,266,587	6,247,939
Financial liabilities [Abstract]
Deposits	8,607,827	8,308,765
Short-term borrowings	0	54,400
Securities sold under agreement to repurchase, short-term	249,880	259,367
Other long-term debt	1,914	1,921
Subordinated debt held by unconsolidated subsidiary trusts	$ 97,939	$ 97,939

DERIVATIVE INSTRUMENTS (Details

DERIVATIVE INSTRUMENTS (Details) - Interest Rate Swap [Member] - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Derivative Instruments [Abstract]
Derivative, notional amount	$ 36.6	$ 37
Derivative weighted average receive rate	4.37%	4.34%
Derivative weighted average pay rate	3.83%	3.84%
Weighted average maturity period	5 years 2 months 12 days	5 years 6 months
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative Instruments [Abstract]
Derivative, notional amount	$ 6.6	$ 6.6
Derivative weighted average receive rate	2.94%	2.92%
Derivative weighted average pay rate	3.11%	3.11%
Weighted average maturity period	14 years 3 months 18 days	14 years 6 months

DERIVATIVE INSTRUMENTS, Cumulat

DERIVATIVE INSTRUMENTS, Cumulative Basis Adjustments for Fair Value Hedges (Details) - Loans [Member] $ in Thousands	Mar. 31, 2019USD ($)
Cumulative Basis Adjustments for Fair Value Hedges [Abstract]
Carrying amount of the hedged assets	$ 7,006
Cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged assets	$ (130)

DERIVATIVE INSTRUMENTS, Fair Va

DERIVATIVE INSTRUMENTS, Fair Values of Derivative Instruments (Details) $ in Thousands	Mar. 31, 2019USD ($)
Fair Values of Derivative Instruments [Abstract]
Derivative assets	$ 855
Derivative liabilities	711
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Other Assets [Member]
Fair Values of Derivative Instruments [Abstract]
Derivative assets	130
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Fair Values of Derivative Instruments [Abstract]
Derivative assets	705
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member] | Accrued Interest and Other Liabilities [Member]
Fair Values of Derivative Instruments [Abstract]
Derivative liabilities	705
Commitments to Originate Real Estate Loans for Sale [Member] | Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Fair Values of Derivative Instruments [Abstract]
Derivative assets	20
Forward Sales Commitments [Member] | Not Designated as Hedging Instrument [Member] | Accrued Interest and Other Liabilities [Member]
Fair Values of Derivative Instruments [Abstract]
Derivative liabilities	$ 6

SEGMENT INFORMATION (Details)

SEGMENT INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Information about reportable segments [Abstract]
Net interest income	$ 86,859	$ 84,624
Provision for loan losses	2,422	3,679
Noninterest revenues	55,696	57,491
Amortization of intangible assets	4,130	4,798
Acquisition expenses	534	(8)
Other operating expenses	83,988	81,541
Income before income taxes	51,481	52,105
Assets	10,916,467	10,966,555	$ 10,607,295
Goodwill	733,503	733,625	$ 733,503
Core deposit intangibles & Other intangibles	70,916	86,959
Eliminations [Member]
Information about reportable segments [Abstract]
Net interest income	0	0
Provision for loan losses	0	0
Noninterest revenues	(769)	(695)
Amortization of intangible assets	0	0
Acquisition expenses	0	0
Other operating expenses	(769)	(695)
Income before income taxes	0	0
Assets	(53,309)	(43,539)
Goodwill	0	0
Core deposit intangibles & Other intangibles	0	0
Banking [Member] | Operating Segments [Member]
Information about reportable segments [Abstract]
Net interest income	86,715	84,530
Provision for loan losses	2,422	3,679
Noninterest revenues	17,348	20,357
Amortization of intangible assets	1,483	1,744
Acquisition expenses	534	(15)
Other operating expenses	59,769	56,955
Income before income taxes	39,855	42,524
Assets	10,699,384	10,736,383
Goodwill	629,916	629,916
Core deposit intangibles & Other intangibles	17,113	23,281
Employee Benefit Services [Member] | Operating Segments [Member]
Information about reportable segments [Abstract]
Net interest income	108	70
Provision for loan losses	0	0
Noninterest revenues	24,670	23,449
Amortization of intangible assets	1,769	2,088
Acquisition expenses	0	7
Other operating expenses	14,279	13,709
Income before income taxes	8,730	7,715
Assets	199,345	205,544
Goodwill	83,275	83,275
Core deposit intangibles & Other intangibles	42,777	50,200
All Other [Member] | Operating Segments [Member]
Information about reportable segments [Abstract]
Net interest income	36	24
Provision for loan losses	0	0
Noninterest revenues	14,447	14,380
Amortization of intangible assets	878	966
Acquisition expenses	0	0
Other operating expenses	10,709	11,572
Income before income taxes	2,896	1,866
Assets	71,047	68,167
Goodwill	20,312	20,434
Core deposit intangibles & Other intangibles	$ 11,026	$ 13,478