Community Bank System (CBU) 10-Q 9 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	COMMUNITY BANK SYSTEM, INC.
Entity Central Index Key	723,188
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		50,609,149
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017

CONSOLIDATED STATEMENTS OF COND

CONSOLIDATED STATEMENTS OF CONDITION (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets:
Cash and cash equivalents	$ 241,480	$ 173,857
Available-for-sale investment securities (cost of $3,021,304 and $2,706,863, respectively)	3,074,260	2,748,656
Other securities, at cost	50,958	35,736
Loans held for sale, at fair value	1,268	2,416
Loans	6,308,720	4,948,562
Allowance for loan losses	(47,983)	(47,233)
Net loans	6,260,737	4,901,329
Goodwill, net	731,505	465,142
Core deposit intangibles, net	26,801	7,107
Other intangibles, net	66,049	8,595
Intangible assets, net	824,355	480,844
Premises and equipment, net	124,470	112,318
Accrued interest and fees receivable	33,359	31,093
Other assets	239,331	180,188
Total assets	10,850,218	8,666,437
Liabilities:
Noninterest-bearing deposits	2,310,954	1,646,039
Interest-bearing deposits	6,295,036	5,429,915
Total deposits	8,605,990	7,075,954
Short-term borrowings	0	146,200
Securities sold under agreement to repurchase, short-term	310,703	0
Other long-term debt	3,586	0
Subordinated debt held by unconsolidated subsidiary trusts	122,808	102,170
Accrued interest and other liabilities	213,886	144,013
Total liabilities	9,256,973	7,468,337
Commitments and contingencies (See Note J)
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; 51,194,178 and 44,950,352 shares issued, respectively	51,194	44,950
Additional paid-in capital	889,886	545,775
Retained earnings	645,180	614,692
Accumulated other comprehensive income	16,177	7,843
Treasury stock, at cost (607,050 shares, including 236,062 shares held by deferred compensation arrangements at September 30, 2017 and 512,937 shares, respectively)	(22,440)	(15,160)
Deferred compensation arrangements (236,062 shares at September 30, 2017)	13,248	0
Total shareholders' equity	1,593,245	1,198,100
Total liabilities and shareholders' equity	$ 10,850,218	$ 8,666,437

CONSOLIDATED STATEMENTS OF CON3

CONSOLIDATED STATEMENTS OF CONDITION (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets:
Available-for-sale investment securities, cost	$ 3,021,304	$ 2,706,863
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)	51,194,178	44,950,352
Treasury stock, shares at cost (in shares)	607,050	512,937
Shares held by deferred compensation arrangements (in shares)	236,062

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Interest income:
Interest and fees on loans	$ 69,498	$ 53,706	$ 184,233	$ 157,865
Interest and dividends on taxable investments	15,228	13,344	43,969	40,956
Interest on nontaxable investments	3,761	4,272	11,665	13,367
Total interest income	88,487	71,322	239,867	212,188
Interest expense:
Interest on deposits	2,123	1,776	5,918	5,542
Interest on borrowings	902	337	1,443	835
Interest on subordinated debt held by unconsolidated subsidiary trusts	1,067	746	2,808	2,161
Total interest expense	4,092	2,859	10,169	8,538
Net interest income	84,395	68,463	229,698	203,650
Provision for loan losses	2,314	1,790	5,603	5,436
Net interest income after provision for loan losses	82,081	66,673	224,095	198,214
Noninterest revenues:
Deposit service fees	18,419	14,894	49,781	43,636
Other banking services	1,704	2,863	4,270	6,039
Employee benefit services	20,767	11,267	58,618	34,949
Insurance revenues	6,344	5,702	19,709	17,340
Wealth management services	5,707	5,226	16,105	15,041
Gain on sales of investment securities	0	0	2	0
Total noninterest revenues	52,941	39,952	148,485	117,005
Noninterest expenses:
Salaries and employee benefits	46,568	38,300	132,776	115,388
Occupancy and equipment	9,106	7,373	25,939	22,445
Data processing and communications	9,313	8,744	28,229	25,886
Amortization of intangible assets	4,949	1,359	11,980	4,204
Legal and professional fees	2,764	1,928	7,796	6,302
Office supplies and postage	2,027	1,713	5,510	5,336
Business development and marketing	2,586	2,004	7,119	6,167
FDIC insurance premiums	827	707	2,505	2,899
Acquisition expenses	580	2	25,192	342
Other expenses	5,056	4,096	13,184	11,282
Total noninterest expenses	83,776	66,226	260,230	200,251
Income before income taxes	51,246	40,399	112,350	114,968
Income taxes	16,003	13,239	33,659	37,548
Net income	$ 35,243	$ 27,160	$ 78,691	$ 77,420
Basic earnings per share (in dollars per share)	$ 0.69	$ 0.61	$ 1.62	$ 1.75
Diluted earnings per share (in dollars per share)	0.68	0.61	1.60	1.74
Cash dividends declared per share (in dollars per share)	$ 0.34	$ 0.32	$ 0.98	$ 0.94

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Pension and other post retirement obligations:
Amortization of actuarial losses included in net periodic pension cost, gross	$ 150	$ 376	$ 625	$ 1,127
Tax effect	(57)	(144)	(240)	(432)
Amortization of actuarial losses included in net periodic pension cost, net	93	232	385	695
Amortization of prior service cost included in net periodic pension cost, gross	(32)	(34)	(91)	(101)
Tax effect	12	13	35	39
Amortization of prior service cost included in net periodic pension cost, net	(20)	(21)	(56)	(62)
Unamortized actuarial gain due to plan merger, gross (See Note H)	0	0	1,858	0
Tax effect	0	0	(710)	0
Unamortized actuarial gain due to plan merger, net	0	0	1,148	0
Other comprehensive income related to pension and other post retirement obligations, net of taxes	73	211	1,477	633
Unrealized gains on available-for-sale securities:
Net unrealized holding (losses)/gains arising during period, gross	(2,490)	(24,465)	11,163	74,332
Tax effect	952	9,310	(4,306)	(28,109)
Net unrealized holding (losses)/gains arising during period, net	(1,538)	(15,155)	6,857	46,223
Other comprehensive (loss)/income related to unrealized (losses)/gains on available-for-sale securities, net of taxes	(1,538)	(15,155)	6,857	46,223
Other comprehensive (loss)/income, net of tax	(1,465)	(14,944)	8,334	46,856
Net income	35,243	27,160	78,691	77,420
Comprehensive income	33,778	$ 12,216	87,025	$ 124,276
Accumulated Other Comprehensive Income By Component:
Unrealized loss for pension and other post-retirement obligations	(26,577)		(26,577)		$ (28,969)
Tax effect	10,093		10,093		11,008
Net unrealized loss for pension and other post-retirement obligations	(16,484)		(16,484)		(17,961)
Unrealized gain on available-for-sale securities	52,956		52,956		41,793
Tax effect	(20,295)		(20,295)		(15,989)
Net unrealized gain on available-for-sale securities	32,661		32,661		25,804
Accumulated other comprehensive income	$ 16,177		$ 16,177		$ 7,843

CONSOLIDATED STATEMENT OF CHANG

CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) - 9 months ended Sep. 30, 2017 - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock [Member]	Deferred Compensation Arrangements [Member]	Total
Balance at Dec. 31, 2016	$ 44,950	$ 545,775	$ 614,692	$ 7,843	$ (15,160)	$ 0	$ 1,198,100
Balance (in shares) at Dec. 31, 2016	44,437,415
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			78,691				78,691
Other comprehensive income, net of tax				8,334			8,334
Cash dividends declared:
Common, $0.98 per share			(48,203)				(48,203)
Common stock issued under employee stock ownership plan	$ 238	3,502					3,740
Common stock issued under employee stock ownership plan (in shares)	237,525
Stock-based compensation		3,985					3,985
Stock issued for acquisitions	$ 6,006	334,731					340,737
Stock issued for acquisitions (in shares)	6,006,301
Deferred compensation arrangements acquired					(10,022)	10,022	0
Deferred compensation arrangements acquired (in shares)	(179,003)
Treasury stock issued to benefit plans, net		1,893			2,742	3,226	7,861
Treasury stock issued to benefit plans, net (in shares)	84,890
Balance at Sep. 30, 2017	$ 51,194	$ 889,886	$ 645,180	$ 16,177	$ (22,440)	$ 13,248	$ 1,593,245
Balance (in shares) at Sep. 30, 2017	50,587,128

CONSOLIDATED STATEMENT OF CHAN7

CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Cash dividends declared:
Dividends declared per common share (in dollars per share)	$ 0.34	$ 0.32	$ 0.98	$ 0.94

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities:
Net income	$ 78,691	$ 77,420
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	12,026	10,742
Amortization of intangible assets	11,980	4,204
Net accretion on securities, loans and borrowings	(4,412)	(3,261)
Stock-based compensation	3,985	3,392
Provision for loan losses	5,603	5,436
Amortization of mortgage servicing rights	374	386
Income from bank-owned life insurance policies	(1,170)	(1,124)
Net loss (gain) on sale of loans and other assets	155	(624)
Change in other assets and other liabilities	31,624	7,257
Net cash provided by operating activities	138,856	103,828
Investing activities:
Proceeds from maturities of available-for-sale investment securities	110,160	86,885
Proceeds from maturities of other investment securities	28,580	9,050
Purchases of available-for-sale investment securities	(59,425)	(40,463)
Purchases of other securities	(12,434)	(4,612)
Net change in loans	120,029	(148,384)
Cash paid for acquisitions, net of cash acquired of $51,793 and $0, respectively	(105,402)	(575)
Settlement of bank-owned life insurance policies	1,779	2,481
Purchases of premises and equipment, net	(7,701)	(7,832)
Net cash provided by/(used in) investing activities	75,586	(103,450)
Financing activities:
Net increase in deposits	81,630	203,945
Net change in borrowings	(193,602)	(167,400)
Issuance of common stock	3,740	7,556
Purchases of treasury stock	(3,226)	(716)
Sales of treasury stock	7,861	6,925
Increase in deferred compensation arrangements	3,226	0
Cash dividends paid	(45,059)	(40,883)
Withholding taxes paid on share-based compensation	(1,389)	(1,473)
Net cash (used in)/provided by financing activities	(146,819)	7,954
Change in cash and cash equivalents	67,623	8,332
Cash and cash equivalents at beginning of period	173,857	153,210
Cash and cash equivalents at end of period	241,480	161,542
Supplemental disclosures of cash flow information:
Cash paid for interest	10,092	8,557
Cash paid for income taxes	33,187	23,717
Supplemental disclosures of noncash financing and investing activities:
Dividends declared and unpaid	17,412	14,220
Transfers from loans to other real estate	2,470	2,137
Acquisitions:
Common stock issued	340,737	0
Fair value of assets acquired, excluding acquired cash and intangibles	1,961,722	0
Fair value of liabilities assumed	$ 1,871,074	$ 0

CONSOLIDATED STATEMENTS OF CAS9

CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Investing activities:
Cash acquired from acquisition	$ 51,793	$ 0

BASIS OF PRESENTATION

BASIS OF PRESENTATION	9 Months Ended
	Sep. 30, 2017
BASIS OF PRESENTATION [Abstract]
BASIS OF PRESENTATION	NOTE A: BASIS OF PRESENTATION The interim financial data as of and for the three and nine months ended September 30, 2017 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 (“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	9 Months Ended
	Sep. 30, 2017
ACQUISITIONS [Abstract]
ACQUISITIONS	NOTE B: ACQUISITIONS On May 12, 2017, the Company completed its acquisition of Merchants Bancshares, Inc. (“Merchants”), parent company of Merchants Bank headquartered in South Burlington, Vermont, for $345.2 million in Company stock and cash, comprised of $82.9 million in cash and the issuance of 4.68 million shares of common stock. The acquisition extends the Company’s footprint into the Vermont and Western Massachusetts markets with the addition of 31 branch locations in Vermont and one location in Massachusetts. This transaction resulted in the acquisition of $1.99 billion of assets, including $1.49 billion of loans and $370.6 million of investment securities, as well as $1.45 billion of deposits and $188.3 million in goodwill. The effects of the acquired assets and liabilities have been included in the consolidated financial statements since that date. Revenues of approximately $16.8 million and direct expenses, which may not include certain shared expenses, of approximately $7.5 million from Merchants were included in the consolidated income statement for the three months ended September 30, 2017. Revenues of approximately $25.8 million and direct expenses, which may not include certain shared expenses, of approximately $11.5 million from Merchants were included in the consolidated income statement for the nine months ended September 30, 2017. On March 1, 2017, the Company, through its subsidiary, OneGroup NY, Inc. (“OneGroup”), completed its acquisition of certain assets of Dryfoos Insurance Agency, Inc. (“Dryfoos”), an insurance agency headquartered in Hazleton, Pennsylvania. The Company paid $3.0 million in cash to acquire the assets of Dryfoos, and recorded goodwill in the amount of $1.7 million and other intangible assets of $1.7 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 February 3, 2017, the Company completed its acquisition of Northeast Retirement Services, Inc. (“NRS”) and its subsidiary Global Trust Company, Inc. (“GTC”), headquartered in Woburn, Massachusetts, for $148.6 million in Company stock and cash. NRS was a privately held corporation focused on providing institutional transfer agency, master recordkeeping services, custom target date fund administration, trust product administration and customized reporting services to institutional clients. Its wholly-owned subsidiary, GTC, is chartered in the State of Maine as a non-depository trust company and provides fiduciary services for collective investment trusts and other products. The acquisition of NRS and GTC, hereafter referred to collectively as NRS, will strengthen and complement the Company’s existing employee benefit services businesses. Upon the completion of the merger, NRS became a wholly-owned subsidiary of Benefit Plans Administrative Services, Inc. (“BPAS”) and operates as Northeast Retirement Services, LLC, a Delaware limited liability company. This transaction resulted in the acquisition of $36.1 million in net tangible assets, principally cash and certificates of deposit, $60.2 million in customer list intangibles that will be amortized using the 150% declining balance method over 10 years, a $24.2 million deferred tax liability associated with the customer list intangible, and $76.5 million in goodwill. The effects of the acquired assets and liabilities have been included in the consolidated financial statements since that date. Revenues of $8.7 million and expenses of $5.8 million from NRS were included in the consolidated income statement for the three months ended September 30, 2017. Revenues of $22.1 million and expenses of $15.1 million from NRS were included in the consolidated income statement for the nine months ended September 30, 2017. On January 1, 2017, the Company, through its subsidiary, OneGroup, acquired certain assets of Benefits Advisory Service, Inc. (“BAS”), a benefits consulting group headquartered in Forest Hills, New York. The Company paid $1.2 million in cash to acquire the assets of BAS and recorded intangible assets of $1.2 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 4, 2016, the Company, through its subsidiary, CBNA Insurance Agency, Inc. (“CBNA Insurance”), completed its acquisition of WJL Agencies Inc. doing business as The Clark Insurance Agencies (“WJL”), an insurance agency operating in Canton, New York. The Company paid $0.6 million in cash for the intangible assets of the company. Goodwill in the amount of $0.3 million and intangible assets in the amount of $0.3 million were recorded 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 August 19, 2016, the Company merged together its insurance subsidiaries and as of that date, the activities of CBNA Insurance were merged into OneGroup. 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 acquisition, and were subject to adjustment based on updated information not available at the time of acquisition. During the second quarter of 2017, the carrying amount of other assets decreased by $2.7 million and other liabilities decreased by $2.4 million as a result of a reclassification of amounts from other assets into other liabilities, and an adjustment to other liabilities as a result of updated information not available at the time of acquisition. Goodwill associated with the NRS acquisition increased $0.3 million during the second quarter as a result of these changes in fair value. During the third quarter of 2017, the carrying amount of investments increased by $0.2 million as a result of updated information not available at the time of acquisition, the carrying amount of loans decreased $0.6 million as a result of an adjustment to the valuation of acquired impaired loans, the carrying amount of premises and equipment increased $3.6 million as a result of updated appraisal information not available at the time of acquisition, and the value of other assets and other liabilities increased $5.5 million and $6.6 million, respectively, as a result of adjustments to accrued income taxes, deferred taxes and certain tax credit arrangements that were recorded on a provisional basis. Goodwill associated with the NRS and Merchants acquisitions decreased $0.1 million and $2.0 million, respectively, as a result of these changes in fair value estimates. The above referenced acquisitions expanded the Company’s geographical presence in New York, Pennsylvania, Vermont, and Western Massachusetts and management expects that the Company will benefit from greater geographic diversity and the advantages of other synergistic business development opportunities. The following table summarizes the estimated fair value of the assets acquired and liabilities assumed after considering the measurement period adjustments described above: 2017 2016 (000s omitted) NRS Merchants Other (1) Total WJL Consideration paid : Cash $ 70,073 $ 82,898 $ 4,224 $ 157,195 $ 575 Community Bank System, Inc. common stock 78,483 262,254 0 340,737 0 Total net consideration paid 148,556 345,152 4,224 497,932 575 Recognized amounts of identifiable assets acquired and liabilities assumed: Cash and cash equivalents 11,063 40,730 0 51,793 0 Investment securities 20,294 370,648 0 390,942 0 Loans 0 1,488,680 0 1,488,680 0 Premises and equipment 411 16,608 27 17,046 0 Accrued interest receivable 72 4,773 0 4,845 0 Other assets 8,088 51,849 272 60,209 0 Core deposit intangibles 0 23,214 0 23,214 0 Other intangibles 60,200 2,857 2,857 65,914 288 Deposits 0 (1,448,406 ) 0 (1,448,406 ) 0 Other liabilities (28,002 ) (11,774 ) (582 ) (40,358 ) 0 Short-term advances 0 (80,000 ) 0 (80,000 ) 0 Securities sold under agreement to repurchase, short-term 0 (278,076 ) 0 (278,076 ) 0 Long-term debt 0 (3,615 ) 0 (3,615 ) 0 Subordinated debt held by unconsolidated subsidiary trusts 0 (20,619 ) 0 (20,619 ) 0 Total identifiable assets, net 72,126 156,869 2,574 231,569 288 Goodwill $ 76,430 $ 188,283 $ 1,650 $ 266,363 $ 287 (1) Includes amounts related to the BAS and Dryfoos acquisitions. Acquired loans that have evidence of deterioration in credit quality since origination and for which it is probable, at acquisition, that the Company will be unable to collect all contractually required payments were aggregated by comparable characteristics and recorded at fair value without a carryover of the related allowance for loan losses. Cash flows for each loan were determined using an estimate of credit losses and rate of prepayments. Projected monthly cash flows were then discounted to present value using a market-based discount rate. The excess of the undiscounted expected cash flows over the estimated fair value is referred to as the “accretable yield” and is recognized into interest income over the remaining lives of the acquired loans. The following is a summary of the loans acquired from Merchants at the date of acquisition: (000s omitted) Acquired Impaired Loans Acquired Non-impaired Loans Total Acquired Loans Contractually required principal and interest at acquisition $ 16,351 $ 1,872,574 $ 1,888,925 Contractual cash flows not expected to be collected (5,794 ) (14,753 ) (20,547 ) Expected cash flows at acquisition 10,557 1,857,821 1,868,378 Interest component of expected cash flows (758 ) (378,940 ) (379,698 ) Fair value of acquired loans $ 9,799 $ 1,478,881 $ 1,488,680 The fair value of checking, savings and money market deposit accounts acquired were assumed to approximate the carrying value as these accounts have no stated maturity and are payable on demand. Certificate of deposit accounts were valued at the present value of the certificates’ expected contractual payments discounted at market rates for similar certificates. The core deposit intangibles and other intangibles related to the Merchants, Dryfoos, BAS and WJL 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 Banking segment for the Merchants acquisition, the Employee Benefit Services segment for NRS, and All Other segments for the Dryfoos, BAS, and WJL acquisitions. Goodwill arising from the Merchants and NRS acquisitions is not deductible for tax purposes. Goodwill arising from the Dryfoos, BAS and WJL acquisitions is deductible for tax purposes. Direct costs related to the acquisitions were expensed as incurred. Merger and acquisition integration-related expenses amount to $0.6 million during the three months ended September 30, 2017, and $25.2 million and $0.3 million for the nine months ended September 30, 2017 and 2016, respectively, and have been separately stated in the Consolidated Statements of Income. Merger and acquisition integration-related expenses for the three months ended September 30, 2016 were immaterial. Supplemental Pro Forma Financial Information The following unaudited condensed pro forma information assumes the Merchants and NRS acquisitions had been completed as of January 1, 2016 for the three and nine months ended September 30, 2016 and September 30, 2017. The pro forma information does not include amounts related to BAS and Dryfoos as the amounts were immaterial. The table below has been prepared for comparative purposes only and is not necessarily indicative of the actual results that would have been attained had the acquisitions occurred as of the beginning of the year presented, nor is it indicative of the Company’s future results. Furthermore, the unaudited pro forma information does not reflect management’s estimate of any revenue-enhancing opportunities nor anticipated cost savings that may have occurred as a result of the integration and consolidation of the acquisitions. The pro forma information set forth below reflects the historical results of Merchants and NRS combined with the Company’s consolidated statement of income with adjustments related to (a) certain purchase accounting fair value adjustments and (b) amortization of customer lists and core deposit intangibles. Acquisition expenses related to the Merchants and NRS transactions totaling $0.5 million and $25.0 million for the three and nine months ended September 30, 2017 were included in the pro forma information as if they were incurred in the first quarter of 2016. Pro Forma (Unaudited) Three Months Ended Pro Forma (Unaudited) Nine Months Ended (000’s omitted) September 30, 2017 September 30, 2016 September 30, 2017 September 30, 2016 Total revenue, net of interest expense $ 136,692 $ 135,026 $ 407,735 $ 400,341 Net income 35,533 32,706 104,197 78,557

ACCOUNTING POLICIES

ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2017
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 59 through 65 of the Annual Report on Form 10-K for the year ended December 31, 2016 filed with the Securities and Exchange Commission (“SEC”) on March 1, 2017. Critical Accounting Policies Acquired Loans Acquired loans are initially recorded at their acquisition date fair values. The carryover of allowance for loan losses is prohibited as any credit losses in the loans are included in the determination of the fair value of the loans at the acquisition date. Fair values for acquired loans are based on a discounted cash flow methodology that involves assumptions and judgments as to credit risk, prepayment risk, liquidity risk, default rates, loss severity, payment speeds, collateral values and discount rate. Acquired Impaired Loans Acquired loans that have evidence of deterioration in credit quality since origination and for which it is probable, at acquisition, that the Company will be unable to collect all contractually required payments are accounted for as impaired loans under Accounting Standards Codification (“ASC”) 310-30. The excess of undiscounted cash flows expected at acquisition over the estimated fair value is referred to as the accretable discount and is recognized into interest income over the remaining life of the loans using the interest method. The difference between contractually required payments at acquisition and the undiscounted cash flows expected to be collected at acquisition is referred to as the non-accretable discount. The non-accretable discount represents estimated future credit losses and other contractually required payments that the Company does not expect to collect. Subsequent decreases in expected cash flows are recognized as impairments through a charge to the provision for loan losses resulting in an increase in the allowance for loan losses. Subsequent improvements in expected cash flows result in a recovery of previously recorded allowance for loan losses or a reversal of a corresponding amount of the non-accretable discount, which the Company then reclassifies as an accretable discount that is recognized into interest income over the remaining life of the loans using the interest method. Acquired loans that met the criteria for non-accrual of interest prior to acquisition may be considered performing upon acquisition, regardless of whether the customer is contractually delinquent, if the Company can reasonably estimate the timing and amount of the expected cash flows on such loans and if the Company expects to fully collect the new carrying value of the loans. As such, the Company may no longer consider the loans to be non-accrual or non-performing and may accrue interest on these loans, including the impact of any accretable discount. Acquired Non-impaired Loans Acquired loans that do not meet the requirements under ASC 310-30 are considered acquired non-impaired loans. The difference between the acquisition date fair value and the outstanding balance represents the fair value adjustment for a loan and includes both credit and interest rate considerations. Fair value adjustments may be discounts (or premiums) to a loan’s cost basis and are accreted (or amortized) to net interest income (or expense) over the loan’s remaining life in accordance with ASC 310-20. Fair value adjustments for revolving loans are accreted (or amortized) using a straight line method. Term loans are accreted (or amortized) using the constant effective yield method. Subsequent to the purchase date, the methods used to estimate the allowance for loan losses for the acquired non-impaired loans are consistent with the policy described below. However, the Company compares the net realizable value of the loans to the carrying value, for loans collectively evaluated for impairment. The carrying value represents the net of the loan’s unpaid principal balance and the remaining purchase discount (or premium) that has yet to be accreted into interest income. When the carrying value exceeds the net realizable value, an allowance for loan loss is recognized. Allowance for Loan Losses Management continually evaluates the credit quality of the Company’s loan portfolio, and performs a formal review of the adequacy of the allowance for loan losses on a quarterly basis. The allowance reflects management’s best estimate of probable losses inherent in the loan portfolio. Determination of the allowance is subjective in nature and requires significant estimates. The Company’s allowance methodology consists of two broad components - general and specific loan loss allocations. The general loan loss allocation is composed of two calculations that are computed on five main loan segments: business lending; consumer direct; consumer indirect; home equity; and consumer mortgage. The first calculation is quantitative and determines an allowance level based on the latest 36 months of historical net charge-off data for each loan class (commercial loans exclude balances with specific loan loss allocations). The second calculation is qualitative and takes into consideration eight qualitative environmental factors: levels of and trends in delinquencies and impaired loans; levels of and trends in charge-offs and recoveries; trends in volume and terms of loans; effects of any changes in risk selection and underwriting standards, and other changes in lending policies, procedures, and practices; experience, ability, and depth of lending management and other relevant staff; national and local economic trends and conditions; industry conditions; and effects of changes in credit concentrations. A component of the qualitative calculation is the unallocated allowance for loan loss. The qualitative and quantitative calculations are added together to determine the general loan loss allocation. The specific loan loss allocation relates to individual commercial loans that are both greater than $0.5 million and in a nonaccruing status with respect to interest. Specific loan losses are based on discounted estimated cash flows, including any cash flows resulting from the conversion of collateral or collateral shortfalls. The allowance levels computed from the specific and general loan loss allocation methods are combined with unallocated allowances and allowances needed for acquired loans to derive the total required allowance for loan losses to be reflected on the Consolidated Statement of Condition. Loan losses are charged off against the allowance, while recoveries of amounts previously charged off are credited to the allowance. A provision for loan losses is charged to operations based on management’s periodic evaluation of factors previously mentioned. Investment Securities The Company can classify its investments in debt and equity securities as held-to-maturity, available-for-sale, or trading. Held-to-maturity securities are those for which the Company has the positive intent and ability to hold until maturity, and are reported at cost, which is adjusted for amortization of premiums and accretion of discounts. Securities classified as available-for-sale are reported at fair value with net unrealized gains and losses reflected as a separate component of shareholders' equity, net of applicable income taxes. None of the Company's investment securities have been classified as trading securities at September 30, 2017. Certain equity securities are stated at cost and include restricted stock of the Federal Reserve Bank of New York (“Federal Reserve”), the Federal Home Loan Bank of New York and the Federal Home Loan Bank of Boston (collectively referred to as “FHLB”). Fair values for investment securities are based upon quoted market prices, where available. If quoted market prices are not available, fair values are based upon quoted market prices of comparable instruments, or a discounted cash flow model using market estimates of interest rates and volatility. The Company conducts an assessment of all securities in an unrealized loss An OTTI loss must be recognized for a debt security in an unrealized loss position if there is intent to sell the security or it is more likely than not the Company will be required to sell the security prior to recovery of its amortized cost basis. In this situation, the amount of loss recognized in income is equal to the difference between the fair value and the amortized cost basis of the security. Even if management does not have the intent, and it is not more likely than not that the Company will be required to sell the securities, an evaluation of the expected cash flows to be received is performed to determine if a credit loss has occurred. For debt securities, a critical component of the evaluation for OTTI is the identification of credit-impaired securities, where the Company does not expect to receive cash flows sufficient to recover the entire amortized cost basis of the security. In the event of a credit loss, only the amount of impairment associated with the credit loss would be recognized in income. The portion of the unrealized loss relating to other factors, such as liquidity conditions in the market or changes in market interest rates, is recorded in accumulated other comprehensive loss. Equity securities are also evaluated to determine whether the unrealized loss is expected to be recoverable based on whether evidence exists to support a realizable value equal to or greater than the amortized cost basis. If it is probable that the amortized cost basis will not be recovered, taking into consideration the estimated recovery period and the ability to hold the equity security until recovery, OTTI is recognized in earnings equal to the difference between the fair value and the amortized cost basis of the security. The specific identification method is used in determining the realized gains and losses on sales of investment securities and OTTI charges. Premiums and discounts on securities are amortized and accreted, respectively, on the interest method basis over the period to maturity or estimated life of the related security. Purchases and sales of securities are recognized on a trade date basis. Intangible Assets Intangible assets include core deposit intangibles, customer relationship intangibles and goodwill arising from acquisitions. Core deposit intangibles and customer relationship intangibles are amortized on either an accelerated or straight-line basis over periods ranging from seven to 20 years. The initial and ongoing carrying value of goodwill and other intangible assets is based upon discounted cash flow modeling techniques that require management to make estimates regarding the amount and timing of expected future cash flows. It also requires use of a discount rate that reflects the current return requirements of the market in relation to present risk-free interest rates, required equity market premiums, peer volatility indicators, and company-specific risk indicators. The Company evaluates goodwill for impairment on an annual basis, or more often if events or circumstances indicate there may be impairment. The implied fair value of a reporting unit’s goodwill is compared to its carrying amount and the impairment loss is measured by the excess of the carrying value over fair value. The fair value of each reporting unit is compared to the carrying amount of such reporting unit in order to determine if impairment is indicated. Retirement Benefits The Company provides defined benefit pension benefits to eligible employees and post-retirement health and life insurance benefits to certain eligible retirees. The Company also provides deferred compensation and supplemental executive retirement plans for selected current and former employees, officers, and directors. Expense under these plans is charged to current operations and consists of several components of net periodic benefit cost based on various actuarial assumptions regarding future experience under the plans, including discount rate, rate of future compensation increases, and expected return on plan assets. Recently Adopted Accounting Pronouncement In March 2016, the FASB issued ASU 2016-09, Compensation – Stock Compensation (Topic 718) New Accounting Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The Company is currently evaluating the effect the guidance will have on the Company’s consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) Topic 840, Leases In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326) In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230) In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350) In March 2017, the FASB issued ASU No. 2017-07, Compensation – Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.

INVESTMENT SECURITIES

INVESTMENT SECURITIES	9 Months Ended
	Sep. 30, 2017
INVESTMENT SECURITIES [Abstract]
INVESTMENT SECURITIES	NOTE D: INVESTMENT SECURITIES The amortized cost and estimated fair value of investment securities as of September 30, 2017 and December 31, 2016 are as follows: September 30, 2017 December 31, 2016 (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 $ 2,040,820 $ 33,703 $ 382 $ 2,074,141 $ 1,876,358 $ 28,522 $ 2,118 $ 1,902,762 Obligations of state and political subdivisions 540,810 17,175 26 557,959 582,655 13,389 1,054 594,990 Government agency mortgage-backed securities 342,838 4,398 2,314 344,922 232,657 5,040 2,467 235,230 Corporate debt securities 2,663 0 1 2,662 5,716 2 31 5,687 Government agency collateralized mortgage obligations 93,922 275 148 94,049 9,225 310 0 9,535 Marketable equity securities 251 276 0 527 252 200 0 452 Total available-for-sale portfolio $ 3,021,304 $ 55,827 $ 2,871 $ 3,074,260 $ 2,706,863 $ 47,463 $ 5,670 $ 2,748,656 Other Securities: Federal Home Loan Bank common stock $ 8,837 $ 8,837 $ 12,191 $ 12,191 Federal Reserve Bank common stock 30,690 30,690 19,781 19,781 Certificates of deposit 5,581 5,581 0 0 Other equity securities 5,850 5,850 3,764 3,764 Total other securities $ 50,958 $ 50,958 $ 35,736 $ 35,736 A summary of investment securities that have been in a continuous unrealized loss position is as follows: As of September 30, 2017 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 24 $ 201,051 $ 382 0 $ 0 $ 0 24 $ 201,051 $ 382 Obligations of state and political subdivisions 9 4,386 21 1 365 5 10 4,751 26 Government agency mortgage-backed securities 94 142,538 1,049 27 35,781 1,265 121 178,319 2,314 Corporate debt securities 1 2,662 1 0 0 0 1 2,662 1 Government agency collateralized mortgage obligations 27 62,406 148 2 2 0 29 62,408 148 Total available-for-sale investment portfolio 155 $ 413,043 $ 1,601 30 $ 36,148 $ 1,270 185 $ 449,191 $ 2,871 As of December 31, 2016 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 13 $ 449,242 $ 2,118 0 $ 0 $ 0 13 $ 449,242 $ 2,118 Obligations of state and political subdivisions 197 102,106 1,054 0 0 0 197 102,106 1,054 Government agency mortgage-backed securities 57 83,862 1,637 15 21,788 830 72 105,650 2,467 Corporate debt securities 1 2,677 31 0 0 0 1 2,677 31 Government agency collateralized mortgage obligations 0 0 0 2 2 0 2 2 0 Total available-for-sale investment portfolio 268 $ 637,887 $ 4,840 17 $ 21,790 $ 830 285 $ 659,677 $ 5,670 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 September 30, 2017 represents OTTI. The amortized cost and estimated fair value of debt securities at September 30, 2017, 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 $ 43,083 $ 43,270 Due after one through five years 1,507,979 1,531,059 Due after five years through ten years 832,917 852,985 Due after ten years 200,314 207,448 Subtotal 2,584,293 2,634,762 Government agency mortgage-backed securities 342,838 344,922 Government agency collateralized mortgage obligations 93,922 94,049 Total $ 3,021,053 $ 3,073,733 As of September 30, 2017, $310.7 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 September 30, 2017 have an overnight and continuous maturity.

LOANS

LOANS	9 Months Ended
	Sep. 30, 2017
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) September 3 0 2017 December 31, 2016 Consumer mortgage $ 2,206,527 $ 1,819,701 Business lending 2,458,981 1,490,076 Consumer indirect 1,034,716 1,044,972 Consumer direct 183,898 191,815 Home equity 424,598 401,998 Gross loans, including deferred origination costs 6,308,720 4,948,562 Allowance for loan losses (47,983 ) (47,233 ) Loans, net of allowance for loan losses $ 6,260,737 $ 4,901,329 The outstanding balance related to credit impaired acquired loans was $21.0 million and $6.6 million at September 30, 2017 and December 31, 2016, respectively. The changes in the accretable discount related to the credit impaired acquired loans are as follows: (000’s omitted) Balance at December 31, 2016 $ 498 Accretion recognized, year-to-date (451 ) Net reclassification to accretable from non-accretable 511 Merchants acquisition 758 Balance at September 30, 2017 $ 1,316 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 September 30, 2017: Legacy Loans (000’s omitted) Past Due 30 – 89 Days 90+ Days Past Due and Still Accruing Nonaccrual Total Past Due Current Total Loans Consumer mortgage $ 11,312 $ 1,275 $ 10,454 $ 23,041 $ 1,695,834 $ 1,718,875 Business lending 8,982 79 3,153 12,214 1,330,222 1,342,436 Consumer indirect 13,729 167 0 13,896 997,402 1,011,298 Consumer direct 1,506 67 0 1,573 175,823 177,396 Home equity 877 1 1,462 2,340 315,918 318,258 Total $ 36,406 $ 1,589 $ 15,069 $ 53,064 $ 4,515,199 $ 4,568,263 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 Consumer mortgage $ 1,949 $ 230 $ 3,526 $ 5,705 $ 0 $ 481,947 $ 487,652 Business lending 3,493 0 1,570 5,063 13,594 1,097,888 1,116,545 Consumer indirect 198 0 0 198 0 23,220 23,418 Consumer direct 131 2 0 133 0 6,369 6,502 Home equity 763 40 1,345 2,148 0 104,192 106,340 Total $ 6,534 $ 272 $ 6,441 $ 13,247 $ 13,594 $ 1,713,616 $ 1,740,457 (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, 2016: Legacy Loans (000’s omitted) Past Due 30 – 89 Days 90+ Days Past Due and Still Accruing Nonaccrual Total Past Due Current Total Loans Consumer mortgage $ 11,379 $ 1,180 $ 11,352 $ 23,911 $ 1,635,849 $ 1,659,760 Business lending 3,921 145 3,811 7,877 1,269,789 1,277,666 Consumer indirect 13,883 166 0 14,049 1,000,776 1,014,825 Consumer direct 1,549 58 0 1,607 180,315 181,922 Home equity 1,250 414 1,437 3,101 315,928 319,029 Total $ 31,982 $ 1,963 $ 16,600 $ 50,545 $ 4,402,657 $ 4,453,202 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 Consumer mortgage $ 1,539 $ 205 $ 2,332 $ 4,076 $ 0 $ 155,865 $ 159,941 Business lending 528 0 1,252 1,780 5,553 205,077 212,410 Consumer indirect 231 3 0 234 0 29,913 30,147 Consumer direct 231 0 0 231 0 9,662 9,893 Home equity 778 905 435 2,118 0 80,851 82,969 Total $ 3,307 $ 1,113 $ 4,019 $ 8,439 $ 5,553 $ 481,368 $ 495,360 (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: September 30, 2017 December 31, 2016 (000’s omitted) Legacy Acquired Total Legacy Acquired Total Pass $ 1,122,422 $ 1,027,919 $ 2,150,341 $ 1,051,005 $ 162,165 $ 1,213,170 Special mention 126,928 34,988 161,916 135,602 29,690 165,292 Classified 93,086 40,044 133,130 90,585 15,002 105,587 Doubtful 0 0 0 474 0 474 Acquired impaired 0 13,594 13,594 0 5,553 5,553 Total $ 1,342,436 $ 1,116,545 $ 2,458,981 $ 1,277,666 $ 212,410 $ 1,490,076 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 September 30, 2017: Legacy Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 1,707,146 $ 1,011,131 $ 177,329 $ 316,795 $ 3,212,401 Nonperforming 11,729 167 67 1,463 13,426 Total $ 1,718,875 $ 1,011,298 $ 177,396 $ 318,258 $ 3,225,827 Acquired Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 483,896 $ 23,418 $ 6,500 $ 104,955 $ 618,769 Nonperforming 3,756 0 2 1,385 5,143 Total $ 487,652 $ 23,418 $ 6,502 $ 106,340 $ 623,912 The following table details the balances in all other loan categories at December 31, 2016: Legacy Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 1,647,228 $ 1,014,659 $ 181,864 $ 317,178 $ 3,160,929 Nonperforming 12,532 166 58 1,851 14,607 Total $ 1,659,760 $ 1,014,825 $ 181,922 $ 319,029 $ 3,175,536 Acquired Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 157,404 $ 30,144 $ 9,893 $ 81,629 $ 279,070 Nonperforming 2,537 3 0 1,340 3,880 Total $ 159,941 $ 30,147 $ 9,893 $ 82,969 $ 282,950 All loan classes are collectively evaluated for impairment except business lending, as described in Note C. A summary of individually evaluated impaired loans as of September 30, 2017 and December 31, 2016 follows: (000’s omitted) September 30, 2017 December 31, 2016 Loans with allowance allocation $ 0 $ 1,109 Loans without allowance allocation 907 556 Unpaid principal balance 907 1,665 Contractual balance 910 3,340 Allowance for loan loss allocated 0 477 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 and nine months ended September 30, 2017 and 2016 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 September 30, 2017 and December 31, 2016 is as follows: September 30, 2017 December 31, 2016 (000’s omitted) Nonaccrual Accruing Total Nonaccrual Accruing Total # Amount # Amount # Amount # Amount # Amount # Amount Consumer mortgage 45 $ 2,131 47 $ 1,940 92 $ 4,071 36 $ 1,520 45 $ 1,956 81 $ 3,476 Business lending 9 453 5 383 14 836 6 91 5 690 11 781 Consumer indirect 0 0 70 839 70 839 0 0 78 771 78 771 Consumer direct 0 0 23 62 23 62 0 0 23 65 23 65 Home equity 11 223 7 207 18 430 14 221 7 216 21 437 Total 65 $ 2,807 152 $ 3,431 217 $ 6,238 56 $ 1,832 158 $ 3,698 214 $ 5,530 The following table presents information related to loans modified in a TDR during the three months and nine months ended September 30, 2017 and 2016. Of the loans noted in the table below, all loans for the three months and nine months ended September 30, 2017 and 2016 were modified due to a Chapter 7 bankruptcy as described previously. The financial effects of these restructurings were immaterial. Three Months Ended September 30, 2017 Three Months Ended September 30, 2016 (000’s omitted) Number of loans modified Outstanding Balance Number of loans modified Outstanding Balance Consumer mortgage 8 $ 540 2 $ 206 Business lending 1 51 0 0 Consumer indirect 8 181 9 89 Consumer direct 1 1 0 0 Home equity 1 8 0 0 Total 19 $ 781 11 $ 295 Nine Months Ended September 30, 2017 Nine Months Ended September 30, 2016 (000’s omitted) Number of loans modified Outstanding Balance Number of loans modified Outstanding Balance Consumer mortgage 15 $ 1,040 9 $ 787 Business lending 4 414 1 29 Consumer indirect 22 323 27 392 Consumer direct 4 7 1 51 Home equity 3 106 3 48 Total 48 $ 1,890 41 $ 1,307 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) Consumer Mortgage Business Lending Consumer Indirect Consumer Direct Home Equity Unallocated Acquired Impaired Total Beginning balance $ 10,197 $ 17,230 $ 13,918 $ 2,945 $ 2,242 $ 856 $ 63 $ 47,451 Charge-offs (198 ) (124 ) (2,328 ) (574 ) 0 0 0 (3,224 ) Recoveries 24 127 1,058 221 12 0 0 1,442 Provision 280 399 1,130 426 (52 ) 142 (11 ) 2,314 Ending balance $ 10,303 $ 17,632 $ 13,778 $ 3,018 $ 2,202 $ 998 $ 52 $ 47,983 Three Months Ended (000’s omitted) Consumer Mortgage Business Lending Consumer Indirect Consumer Direct Home Equity Unallocated Acquired Impaired Total Beginning balance $ 9,853 $ 16,949 $ 13,215 $ 3,020 $ 2,500 $ 850 $ 139 $ 46,526 Charge-offs (202 ) (284 ) (2,037 ) (395 ) (6 ) 0 0 (2,924 ) Recoveries 12 220 892 246 27 0 0 1,397 Provision 305 (283 ) 1,503 170 10 85 0 1,790 Ending balance $ 9,968 $ 16,602 $ 13,573 $ 3,041 $ 2,531 $ 935 $ 139 $ 46,789 Nine Months Ended (000’s omitted) Consumer Mortgage Business Lending Consumer Indirect Consumer Direct Home Equity Unallocated Acquired Impaired Total Beginning balance $ 10,094 $ 17,220 $ 13,782 $ 2,979 $ 2,399 $ 651 $ 108 $ 47,233 Charge-offs (541 ) (1,062 ) (5,969 ) (1,463 ) (228 ) 0 (184 ) (9,447 ) Recoveries 42 481 3,379 648 44 0 0 4,594 Provision 708 993 2,586 854 (13 ) 347 128 5,603 Ending balance $ 10,303 $ 17,632 $ 13,778 $ 3,018 $ 2,202 $ 998 $ 52 $ 47,983 Nine Months Ended (000’s omitted) Consumer Mortgage Business Lending Consumer Indirect Consumer Direct Home Equity Unallocated Acquired Impaired Total Beginning balance $ 10,198 $ 15,749 $ 12,422 $ 2,997 $ 2,666 $ 1,201 $ 168 $ 45,401 Charge-offs (445 ) (1,263 ) (5,439 ) (1,246 ) (142 ) 0 (26 ) (8,561 ) Recoveries 96 511 3,146 705 55 0 0 4,513 Provision 119 1,605 3,444 585 (48 ) (266 ) (3 ) 5,436 Ending balance $ 9,968 $ 16,602 $ 13,573 $ 3,041 $ 2,531 $ 935 $ 139 $ 46,789

GOODWILL AND IDENTIFIABLE INTAN

GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS	9 Months Ended
	Sep. 30, 2017
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: September 30, 2017 December 31, 2016 (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 $ (36,101 ) $ 26,801 $ 39,688 $ (32,581 ) $ 7,107 Other intangibles 83,767 $ (17,718 ) 66,049 17,853 (9,258 ) 8,595 Total amortizing intangibles $ 146,669 $ (53,819 ) $ 92,850 $ 57,541 $ (41,839 ) $ 15,702 The estimated aggregate amortization expense for each of the five succeeding fiscal years ended December 31 is as follows: (000's omitted) Oct - Dec 2017 $ 4,904 2018 17,259 2019 14,502 2020 12,043 2021 10,288 Thereafter 33,854 Total $ 92,850 Shown below are the components of the Company’s goodwill at December 31, 2016 and September 30, 2017: (000’s omitted) December 31, 2016 Activity September 30, 2017 Goodwill $ 469,966 $ 266,363 $ 736,329 Accumulated impairment $ (4,824 ) $ 0 $ (4,824 ) Goodwill, net $ 465,142 $ 266,363 $ 731,505

MANDATORILY REDEEMABLE PREFERRE

MANDATORILY REDEEMABLE PREFERRED SECURITIES	9 Months Ended
	Sep. 30, 2017
MANDATORILY REDEEMABLE PREFERRED SECURITIES [Abstract]
MANDATORILY REDEEMABLE PREFERRED SECURITIES	NOTE G: MANDATORILY REDEEMABLE PREFERRED SECURITIES The Company sponsors three business trusts, Community Statutory Trust III (“CST III”), 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 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 CST III 7/31/2001 $24.5 million 3 month LIBOR plus 3.58% (4.89%) 7/31/2031 Par CCT IV 12/8/2006 $75.0 million 3 month LIBOR plus 1.65% (2.97%) 12/15/2036 Par MBVT I 12/15/2004 $20.6 million 3 month LIBOR plus 1.95% (3.27%) 12/31/2034 Par

BENEFIT PLANS

BENEFIT PLANS	9 Months Ended
	Sep. 30, 2017
BENEFIT PLANS [Abstract]
BENEFIT PLANS	NOTE H: 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. Effective May 12, 2017, the Merchants Bank Pension Plan was merged into the Community Bank System, Inc. Pension Plan and the combined plan was revalued resulting in an additional unamortized actuarial gain of approximately $1.9 million, due primarily to a gain on plan assets that was partially offset by a decrease in the discount rate from 4.50% to 4.40% as of the valuation date. The net periodic benefit cost for the three and nine months ended September 30, 2017 and 2016 is as follows: Pension Benefits Post-retirement Benefits Three Months Ended September 30, Nine Months Ended September 30, Three Months Ended September 30, Nine Months Ended September 30, (000's omitted) 2017 2016 2017 2016 2017 2016 2017 2016 Service cost $ 1,037 $ 1,027 $ 3,143 $ 3,079 $ 0 $ 0 $ 0 $ 0 Interest cost 1,453 1,406 4,265 4,218 19 20 57 61 Expected return on plan assets (3,448 ) (2,961 ) (9,977 ) (8,882 ) 0 0 0 0 Amortization of unrecognized net loss 148 377 619 1,131 2 (1 ) 6 (4 ) Amortization of prior service cost 13 11 43 33 (45 ) (45 ) (134 ) (134 ) Net periodic benefit cost (income) $ (797 ) $ (140 ) $ (1,907 ) $ (421 ) $ (24 ) $ (26 ) $ (71 ) $ (77 )

EARNINGS PER SHARE

EARNINGS PER SHARE	9 Months Ended
	Sep. 30, 2017
EARNINGS PER SHARE [Abstract]
EARNINGS PER SHARE	NOTE I: 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 September 30, 2017. 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 adjusted for the dilutive effect of restricted stock 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 0.2 million weighted-average anti-dilutive stock options outstanding for the three months ended September 30, 2017, and 0.1 million weighted-average anti-dilutive stock options outstanding for the nine months ended September 30, 2017, compared to no weighted-average anti-dilutive stock options outstanding for the three months ended September 30, 2016, and approximately 0.3 million weighted-average anti-dilutive stock options outstanding for the nine months ended September 30, 2016 that were not included in the computation below. The following is a reconciliation of basic to diluted earnings per share for the three and nine months ended September 30, 2017 and 2016: Three Months Ended September 30, Nine Months Ended September 30, (000's omitted, except per share data) 2017 2016 2017 2016 Net income $ 35,243 $ 27,160 $ 78,691 $ 77,420 Income attributable to unvested stock-based compensation awards (164 ) (157 ) (387 ) (398 ) Income available to common shareholders $ 35,079 $ 27,003 $ 78,304 $ 77,022 Weighted-average common shares outstanding – basic 50,703 44,184 48,189 44,023 Basic earnings per share $ 0.69 $ 0.61 $ 1.62 $ 1.75 Net income $ 35,243 $ 27,160 $ 78,691 $ 77,420 Income attributable to unvested stock-based compensation awards (164 ) (157 ) (387 ) (398 ) Income available to common shareholders $ 35,079 $ 27,003 $ 78,304 $ 77,022 Weighted-average common shares outstanding – basic 50,703 44,184 48,189 44,023 Assumed exercise of stock options 585 394 640 359 Weighted-average common shares outstanding – diluted 51,288 44,578 48,829 44,382 Diluted earnings per share $ 0.68 $ 0.61 $ 1.60 $ 1.74 Stock Repurchase Program At its December 2016 meeting, the Company’s Board of Directors (the “Board”) approved a stock repurchase program authorizing the repurchase of up to 2.2 million shares of the Company’s common stock in accordance with securities laws and regulations, through December 31, 2017. 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 nine months of 2017.

COMMITMENTS, CONTINGENT LIABILI

COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS	9 Months Ended
	Sep. 30, 2017
COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS [Abstract]
COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS	NOTE J: 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) September 30, 2017 December 31, 2016 Commitments to extend credit $ 1,038,125 $ 773,442 Standby letters of credit 24,058 22,656 Total $ 1,062,183 $ 796,098 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 September 30, 2017, 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	9 Months Ended
	Sep. 30, 2017
FAIR VALUE [Abstract]
FAIR VALUE	NOTE K: 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: · Quoted prices in active markets for identical assets or liabilities. · 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. · 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. September 30, 2017 (000's omitted) Level 1 Level 2 Level 3 Total Fair Value Available-for-sale investment securities: U.S. Treasury and agency securities $ 1,927,872 $ 146,269 $ 0 $ 2,074,141 Obligations of state and political subdivisions 0 557,959 0 557,959 Government agency mortgage-backed securities 0 344,922 0 344,922 Corporate debt securities 0 2,662 0 2,662 Government agency collateralized mortgage obligations 0 94,049 0 94,049 Marketable equity securities 527 0 0 527 Total available-for-sale investment securities 1,928,399 1,145,861 0 3,074,260 Mortgage loans held for sale 0 1,268 0 1,268 Commitments to originate real estate loans for sale 0 0 152 152 Forward sales commitments 0 (44 ) 0 (44 ) Interest rate swap agreements asset 0 1,102 0 1,102 Interest rate swap agreements liability 0 (890 ) 0 (890 ) Total $ 1,928,399 $ 1,147,297 $ 152 $ 3,075,848 December 31, 2016 (000's omitted) Level 1 Level 2 Level 3 Total Fair Value Available-for-sale investment securities: U.S. Treasury and agency securities $ 1,902,762 $ 0 $ 0 $ 1,902,762 Obligations of state and political subdivisions 0 594,990 0 594,990 Government agency mortgage-backed securities 0 235,230 0 235,230 Corporate debt securities 0 5,687 0 5,687 Government agency collateralized mortgage obligations 0 9,535 0 9,535 Marketable equity securities 452 0 0 452 Total available-for-sale investment securities 1,903,214 845,442 0 2,748,656 Mortgage loans held for sale 0 2,416 0 2,416 Commitments to originate real estate loans for sale 0 0 54 54 Forward sales commitments 0 3 0 3 Total $ 1,903,214 $ 847,861 $ 54 $ 2,751,129 The valuation techniques used to measure fair value for the items in the table above are as follows: · Available-for-sale investment 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 at September 30, 2017 was approximately $1.3 million. The unrealized gain on mortgage loans held for sale was recognized in mortgage banking and other income in the consolidated statement 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 our 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 summarized in the following tables: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (000's omitted) Commitments to Originate Real Estate Loans for Sale Commitments to Originate Real Estate Loans for Sale Commitments to Originate Real Estate Loans for Sale Commitments to Originate Real Estate Loans for Sale Beginning balance $ 179 $ 361 $ 54 $ 117 Total losses included in earnings (1) (179 ) (361 ) (347 ) (760 ) Commitments to originate real estate loans held for sale, net 152 474 445 1,117 Ending balance $ 152 $ 474 $ 152 $ 474 (1) 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. September 30, 2017 December 31, 2016 (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 $ 0 $ 0 $ 0 $ 0 $ 633 $ 633 Other real estate owned 0 0 1,873 1,873 0 0 1,966 1,966 Total $ 0 $ 0 $ 1,873 $ 1,873 $ 0 $ 0 $ 2,599 $ 2,599 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% to 65.9% at September 30, 2017 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 September 30, 2017. 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 September 30, 2017 Valuation Technique Significant Unobservable Inputs Significant Unobservable Input Range (Weighted Average) Other real estate owned $ 1,873 Fair Value of Collateral Estimated cost of disposal/market adjustment 9.0% - 65.9% (30.3 %) Commitments to originate real estate loans for sale 152 Discounted cash flow Embedded servicing value 1 % (000's omitted) Fair Value at December 31, 2016 Valuation Technique Significant Unobservable Inputs Significant Unobservable Input Range (Weighted Average) Other real estate owned $ 1,966 Fair value of collateral Estimated cost of disposal/market adjustment 9.0% - 97.0% (29.6 %) Impaired loans 633 Fair value of collateral Estimated cost of disposal/market adjustment 15.0% - 50.0% (36.5 %) Commitments to originate real estate loans for sale 54 Discounted cash flow Embedded servicing value 1 % 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 September 30, 2017 and December 31, 2016 are as follows: September 30, 2017 December 31, 2016 (000's omitted) Carrying Value Fair Value Carrying Value Fair Value Financial assets: Net loans $ 6,260,737 $ 6,321,781 $ 4,901,329 $ 4,935,140 Financial liabilities: Deposits 8,605,990 8,592,459 7,075,954 7,071,191 Short-term borrowings 0 0 146,200 146,200 Securities sold under agreement to repurchase, short-term 310,703 310,703 0 0 Other long-term debt 3,586 3,568 0 0 Subordinated debt held by unconsolidated subsidiary trusts 122,808 122,808 102,170 90,144 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 FHLB overnight advances and securities sold under agreement to repurchase, short-term, is the amount payable on demand at the reporting date. Fair values for long-term borrowings 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	9 Months Ended
	Sep. 30, 2017
DERIVATIVE INSTRUMENTS [Abstract]
DERIVATIVE INSTRUMENTS	NOTE L: 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 September 30, 2017. The effect of the changes to these derivatives for the three and nine 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 $39.4 million at September 30, 2017. 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 $39.4 million. The weighted average receive rate of these interest rate swaps was 3.12%, the weighted average pay rate was 3.84% and the weighted average maturity was 6.7 years. The fair values of $0.9 million and $0.9 million were reflected in other assets and other liabilities, respectively, in the accompanying consolidated statement of condition at September 30, 2017. Hedge accounting has not been applied for these derivatives. Since the terms of the swaps with our 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 our results of operations. The Company also acquired interest rate swaps from the Merchants acquisition with notional amounts totaling $7.0 million at September 30, 2017 that were designated as fair value hedges of certain fixed rate loans with municipalities. At September 30, 2017, the weighted average receive rate of these interest rate swaps was 2.13%, the weighted average pay rate was 3.11% and the weighted average maturity was 15.8 years. The fair value of $0.2 million at September 30, 2017, was reflected as a reduction to loans and an increase to other assets. The ineffective portion of the interest swaps was immaterial and as such, amounts are not recognized in earnings. The Company assessed its counterparty risk at September 30, 2017 and determined any credit risk inherent in our derivative contracts was not material. Information about the fair value of derivative financial instruments can be found in Note K to these consolidated financial statements.

SEGMENT INFORMATION

SEGMENT INFORMATION	9 Months Ended
	Sep. 30, 2017
SEGMENT INFORMATION [Abstract]
SEGMENT INFORMATION	NOTE M: 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 Northern, Central, and Western 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 (formerly Harbridge Consulting Group, LLC), BPAS Trust Company of Puerto Rico, NRS, GTC, and Hand Benefits & Trust Company, provides employee benefit trust, collective investment fund, retirement plan administration, 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 Community Investment Services, Inc. (“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 September 30, 2017 Net interest income $ 84,227 $ 104 $ 64 $ 0 $ 84,395 Provision for loan losses 2,314 0 0 0 2,314 Noninterest revenues 20,120 21,207 12,298 (684 ) 52,941 Amortization of intangible assets 1,796 2,323 830 0 4,949 Acquisition expenses 534 11 35 0 580 Other operating expenses 56,926 12,788 9,217 (684 ) 78,247 Income before income taxes $ 42,777 $ 6,189 $ 2,280 $ 0 $ 51,246 Assets $ 10,613,065 $ 226,812 $ 77,802 $ (67,461 ) $ 10,850,218 Goodwill $ 629,153 $ 84,448 $ 17,904 $ 0 $ 731,505 Three Months Ended September 30, 2016 Net interest income $ 68,375 $ 39 $ 49 $ 0 $ 68,463 Provision for loan losses 1,790 0 0 0 1,790 Noninterest revenues 17,756 11,680 11,139 (623 ) 39,952 Amortization of intangible assets 665 96 598 0 1,359 Acquisition expenses 2 0 0 0 2 Other operating expenses 47,736 9,020 8,732 (623 ) 64,865 Income before income taxes $ 35,938 $ 2,603 $ 1,858 $ 0 $ 40,399 Assets $ 8,658,308 $ 36,706 $ 72,147 $ (39,415 ) $ 8,727,746 Goodwill $ 440,870 $ 8,019 $ 16,253 $ 0 $ 465,142 (000's omitted) Banking Employee Benefit Services All Other Eliminations Consolidated Total Nine Months Ended September 30, 2017 Net interest income $ 229,233 $ 276 $ 189 $ 0 $ 229,698 Provision for loan losses 5,603 0 0 0 5,603 Noninterest revenues 54,049 59,961 36,510 (2,035 ) 148,485 Amortization of intangible assets 3,520 6,256 2,204 0 11,980 Acquisition expenses 23,784 1,190 218 0 25,192 Other operating expenses 160,311 37,225 27,557 (2,035 ) 223,058 Income before income taxes $ 90,064 $ 15,566 $ 6,720 $ 0 $ 112,350 Nine Months Ended September 30, 2016 Net interest income $ 203,394 $ 117 $ 139 $ 0 $ 203,650 Provision for loan losses 5,436 0 0 0 5,436 Noninterest revenues 49,663 36,137 32,989 (1,784 ) 117,005 Amortization of intangible assets 2,075 326 1,803 0 4,204 Acquisition expenses 101 0 241 0 342 Other operating expenses 143,781 27,899 25,809 (1,784 ) 195,705 Income before income taxes $ 101,664 $ 8,029 $ 5,275 $ 0 $ 114,968

BASIS OF PRESENTATION (Policies

BASIS OF PRESENTATION (Policies)	9 Months Ended
	Sep. 30, 2017
BASIS OF PRESENTATION [Abstract]
Basis of Presentation	The interim financial data as of and for the three and nine months ended September 30, 2017 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 (“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)	9 Months Ended
	Sep. 30, 2017
ACCOUNTING POLICIES [Abstract]
Acquired Loans	Acquired Loans Acquired loans are initially recorded at their acquisition date fair values. The carryover of allowance for loan losses is prohibited as any credit losses in the loans are included in the determination of the fair value of the loans at the acquisition date. Fair values for acquired loans are based on a discounted cash flow methodology that involves assumptions and judgments as to credit risk, prepayment risk, liquidity risk, default rates, loss severity, payment speeds, collateral values and discount rate. Acquired Impaired Loans Acquired loans that have evidence of deterioration in credit quality since origination and for which it is probable, at acquisition, that the Company will be unable to collect all contractually required payments are accounted for as impaired loans under Accounting Standards Codification (“ASC”) 310-30. The excess of undiscounted cash flows expected at acquisition over the estimated fair value is referred to as the accretable discount and is recognized into interest income over the remaining life of the loans using the interest method. The difference between contractually required payments at acquisition and the undiscounted cash flows expected to be collected at acquisition is referred to as the non-accretable discount. The non-accretable discount represents estimated future credit losses and other contractually required payments that the Company does not expect to collect. Subsequent decreases in expected cash flows are recognized as impairments through a charge to the provision for loan losses resulting in an increase in the allowance for loan losses. Subsequent improvements in expected cash flows result in a recovery of previously recorded allowance for loan losses or a reversal of a corresponding amount of the non-accretable discount, which the Company then reclassifies as an accretable discount that is recognized into interest income over the remaining life of the loans using the interest method. Acquired loans that met the criteria for non-accrual of interest prior to acquisition may be considered performing upon acquisition, regardless of whether the customer is contractually delinquent, if the Company can reasonably estimate the timing and amount of the expected cash flows on such loans and if the Company expects to fully collect the new carrying value of the loans. As such, the Company may no longer consider the loans to be non-accrual or non-performing and may accrue interest on these loans, including the impact of any accretable discount. Acquired Non-impaired Loans Acquired loans that do not meet the requirements under ASC 310-30 are considered acquired non-impaired loans. The difference between the acquisition date fair value and the outstanding balance represents the fair value adjustment for a loan and includes both credit and interest rate considerations. Fair value adjustments may be discounts (or premiums) to a loan’s cost basis and are accreted (or amortized) to net interest income (or expense) over the loan’s remaining life in accordance with ASC 310-20. Fair value adjustments for revolving loans are accreted (or amortized) using a straight line method. Term loans are accreted (or amortized) using the constant effective yield method. Subsequent to the purchase date, the methods used to estimate the allowance for loan losses for the acquired non-impaired loans are consistent with the policy described below. However, the Company compares the net realizable value of the loans to the carrying value, for loans collectively evaluated for impairment. The carrying value represents the net of the loan’s unpaid principal balance and the remaining purchase discount (or premium) that has yet to be accreted into interest income. When the carrying value exceeds the net realizable value, an allowance for loan loss is recognized.
Allowance for Loan Losses	Allowance for Loan Losses Management continually evaluates the credit quality of the Company’s loan portfolio, and performs a formal review of the adequacy of the allowance for loan losses on a quarterly basis. The allowance reflects management’s best estimate of probable losses inherent in the loan portfolio. Determination of the allowance is subjective in nature and requires significant estimates. The Company’s allowance methodology consists of two broad components - general and specific loan loss allocations. The general loan loss allocation is composed of two calculations that are computed on five main loan segments: business lending; consumer direct; consumer indirect; home equity; and consumer mortgage. The first calculation is quantitative and determines an allowance level based on the latest 36 months of historical net charge-off data for each loan class (commercial loans exclude balances with specific loan loss allocations). The second calculation is qualitative and takes into consideration eight qualitative environmental factors: levels of and trends in delinquencies and impaired loans; levels of and trends in charge-offs and recoveries; trends in volume and terms of loans; effects of any changes in risk selection and underwriting standards, and other changes in lending policies, procedures, and practices; experience, ability, and depth of lending management and other relevant staff; national and local economic trends and conditions; industry conditions; and effects of changes in credit concentrations. A component of the qualitative calculation is the unallocated allowance for loan loss. The qualitative and quantitative calculations are added together to determine the general loan loss allocation. The specific loan loss allocation relates to individual commercial loans that are both greater than $0.5 million and in a nonaccruing status with respect to interest. Specific loan losses are based on discounted estimated cash flows, including any cash flows resulting from the conversion of collateral or collateral shortfalls. The allowance levels computed from the specific and general loan loss allocation methods are combined with unallocated allowances and allowances needed for acquired loans to derive the total required allowance for loan losses to be reflected on the Consolidated Statement of Condition. Loan losses are charged off against the allowance, while recoveries of amounts previously charged off are credited to the allowance. A provision for loan losses is charged to operations based on management’s periodic evaluation of factors previously mentioned.
Investment Securities	Investment Securities The Company can classify its investments in debt and equity securities as held-to-maturity, available-for-sale, or trading. Held-to-maturity securities are those for which the Company has the positive intent and ability to hold until maturity, and are reported at cost, which is adjusted for amortization of premiums and accretion of discounts. Securities classified as available-for-sale are reported at fair value with net unrealized gains and losses reflected as a separate component of shareholders' equity, net of applicable income taxes. None of the Company's investment securities have been classified as trading securities at September 30, 2017. Certain equity securities are stated at cost and include restricted stock of the Federal Reserve Bank of New York (“Federal Reserve”), the Federal Home Loan Bank of New York and the Federal Home Loan Bank of Boston (collectively referred to as “FHLB”). Fair values for investment securities are based upon quoted market prices, where available. If quoted market prices are not available, fair values are based upon quoted market prices of comparable instruments, or a discounted cash flow model using market estimates of interest rates and volatility. The Company conducts an assessment of all securities in an unrealized loss An OTTI loss must be recognized for a debt security in an unrealized loss position if there is intent to sell the security or it is more likely than not the Company will be required to sell the security prior to recovery of its amortized cost basis. In this situation, the amount of loss recognized in income is equal to the difference between the fair value and the amortized cost basis of the security. Even if management does not have the intent, and it is not more likely than not that the Company will be required to sell the securities, an evaluation of the expected cash flows to be received is performed to determine if a credit loss has occurred. For debt securities, a critical component of the evaluation for OTTI is the identification of credit-impaired securities, where the Company does not expect to receive cash flows sufficient to recover the entire amortized cost basis of the security. In the event of a credit loss, only the amount of impairment associated with the credit loss would be recognized in income. The portion of the unrealized loss relating to other factors, such as liquidity conditions in the market or changes in market interest rates, is recorded in accumulated other comprehensive loss. Equity securities are also evaluated to determine whether the unrealized loss is expected to be recoverable based on whether evidence exists to support a realizable value equal to or greater than the amortized cost basis. If it is probable that the amortized cost basis will not be recovered, taking into consideration the estimated recovery period and the ability to hold the equity security until recovery, OTTI is recognized in earnings equal to the difference between the fair value and the amortized cost basis of the security. The specific identification method is used in determining the realized gains and losses on sales of investment securities and OTTI charges. Premiums and discounts on securities are amortized and accreted, respectively, on the interest method basis over the period to maturity or estimated life of the related security. Purchases and sales of securities are recognized on a trade date basis.
Intangible Assets	Intangible Assets Intangible assets include core deposit intangibles, customer relationship intangibles and goodwill arising from acquisitions. Core deposit intangibles and customer relationship intangibles are amortized on either an accelerated or straight-line basis over periods ranging from seven to 20 years. The initial and ongoing carrying value of goodwill and other intangible assets is based upon discounted cash flow modeling techniques that require management to make estimates regarding the amount and timing of expected future cash flows. It also requires use of a discount rate that reflects the current return requirements of the market in relation to present risk-free interest rates, required equity market premiums, peer volatility indicators, and company-specific risk indicators. The Company evaluates goodwill for impairment on an annual basis, or more often if events or circumstances indicate there may be impairment. The implied fair value of a reporting unit’s goodwill is compared to its carrying amount and the impairment loss is measured by the excess of the carrying value over fair value. The fair value of each reporting unit is compared to the carrying amount of such reporting unit in order to determine if impairment is indicated.
Retirement Benefits	Retirement Benefits The Company provides defined benefit pension benefits to eligible employees and post-retirement health and life insurance benefits to certain eligible retirees. The Company also provides deferred compensation and supplemental executive retirement plans for selected current and former employees, officers, and directors. Expense under these plans is charged to current operations and consists of several components of net periodic benefit cost based on various actuarial assumptions regarding future experience under the plans, including discount rate, rate of future compensation increases, and expected return on plan assets.
Recently Adopted Accounting Pronouncement	Recently Adopted Accounting Pronouncement In March 2016, the FASB issued ASU 2016-09, Compensation – Stock Compensation (Topic 718)
New Accounting Pronouncements	New Accounting Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The Company is currently evaluating the effect the guidance will have on the Company’s consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) Topic 840, Leases In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326) In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230) In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350) In March 2017, the FASB issued ASU No. 2017-07, Compensation – Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	9 Months Ended
	Sep. 30, 2017
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: 2017 2016 (000s omitted) NRS Merchants Other (1) Total WJL Consideration paid : Cash $ 70,073 $ 82,898 $ 4,224 $ 157,195 $ 575 Community Bank System, Inc. common stock 78,483 262,254 0 340,737 0 Total net consideration paid 148,556 345,152 4,224 497,932 575 Recognized amounts of identifiable assets acquired and liabilities assumed: Cash and cash equivalents 11,063 40,730 0 51,793 0 Investment securities 20,294 370,648 0 390,942 0 Loans 0 1,488,680 0 1,488,680 0 Premises and equipment 411 16,608 27 17,046 0 Accrued interest receivable 72 4,773 0 4,845 0 Other assets 8,088 51,849 272 60,209 0 Core deposit intangibles 0 23,214 0 23,214 0 Other intangibles 60,200 2,857 2,857 65,914 288 Deposits 0 (1,448,406 ) 0 (1,448,406 ) 0 Other liabilities (28,002 ) (11,774 ) (582 ) (40,358 ) 0 Short-term advances 0 (80,000 ) 0 (80,000 ) 0 Securities sold under agreement to repurchase, short-term 0 (278,076 ) 0 (278,076 ) 0 Long-term debt 0 (3,615 ) 0 (3,615 ) 0 Subordinated debt held by unconsolidated subsidiary trusts 0 (20,619 ) 0 (20,619 ) 0 Total identifiable assets, net 72,126 156,869 2,574 231,569 288 Goodwill $ 76,430 $ 188,283 $ 1,650 $ 266,363 $ 287 (1) Includes amounts related to the BAS and Dryfoos acquisitions.
Summary of Loans Acquired	The following is a summary of the loans acquired from Merchants at the date of acquisition: (000s omitted) Acquired Impaired Loans Acquired Non-impaired Loans Total Acquired Loans Contractually required principal and interest at acquisition $ 16,351 $ 1,872,574 $ 1,888,925 Contractual cash flows not expected to be collected (5,794 ) (14,753 ) (20,547 ) Expected cash flows at acquisition 10,557 1,857,821 1,868,378 Interest component of expected cash flows (758 ) (378,940 ) (379,698 ) Fair value of acquired loans $ 9,799 $ 1,478,881 $ 1,488,680
Pro Forma Financial Information	Acquisition expenses related to the Merchants and NRS transactions totaling $0.5 million and $25.0 million for the three and nine months ended September 30, 2017 were included in the pro forma information as if they were incurred in the first quarter of 2016. Pro Forma (Unaudited) Three Months Ended Pro Forma (Unaudited) Nine Months Ended (000’s omitted) September 30, 2017 September 30, 2016 September 30, 2017 September 30, 2016 Total revenue, net of interest expense $ 136,692 $ 135,026 $ 407,735 $ 400,341 Net income 35,533 32,706 104,197 78,557

INVESTMENT SECURITIES (Tables)

INVESTMENT SECURITIES (Tables)	9 Months Ended
	Sep. 30, 2017
INVESTMENT SECURITIES [Abstract]
Amortized Cost and Estimated Fair Value of Investment Securities	The amortized cost and estimated fair value of investment securities as of September 30, 2017 and December 31, 2016 are as follows: September 30, 2017 December 31, 2016 (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 $ 2,040,820 $ 33,703 $ 382 $ 2,074,141 $ 1,876,358 $ 28,522 $ 2,118 $ 1,902,762 Obligations of state and political subdivisions 540,810 17,175 26 557,959 582,655 13,389 1,054 594,990 Government agency mortgage-backed securities 342,838 4,398 2,314 344,922 232,657 5,040 2,467 235,230 Corporate debt securities 2,663 0 1 2,662 5,716 2 31 5,687 Government agency collateralized mortgage obligations 93,922 275 148 94,049 9,225 310 0 9,535 Marketable equity securities 251 276 0 527 252 200 0 452 Total available-for-sale portfolio $ 3,021,304 $ 55,827 $ 2,871 $ 3,074,260 $ 2,706,863 $ 47,463 $ 5,670 $ 2,748,656 Other Securities: Federal Home Loan Bank common stock $ 8,837 $ 8,837 $ 12,191 $ 12,191 Federal Reserve Bank common stock 30,690 30,690 19,781 19,781 Certificates of deposit 5,581 5,581 0 0 Other equity securities 5,850 5,850 3,764 3,764 Total other securities $ 50,958 $ 50,958 $ 35,736 $ 35,736
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 September 30, 2017 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 24 $ 201,051 $ 382 0 $ 0 $ 0 24 $ 201,051 $ 382 Obligations of state and political subdivisions 9 4,386 21 1 365 5 10 4,751 26 Government agency mortgage-backed securities 94 142,538 1,049 27 35,781 1,265 121 178,319 2,314 Corporate debt securities 1 2,662 1 0 0 0 1 2,662 1 Government agency collateralized mortgage obligations 27 62,406 148 2 2 0 29 62,408 148 Total available-for-sale investment portfolio 155 $ 413,043 $ 1,601 30 $ 36,148 $ 1,270 185 $ 449,191 $ 2,871 As of December 31, 2016 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 13 $ 449,242 $ 2,118 0 $ 0 $ 0 13 $ 449,242 $ 2,118 Obligations of state and political subdivisions 197 102,106 1,054 0 0 0 197 102,106 1,054 Government agency mortgage-backed securities 57 83,862 1,637 15 21,788 830 72 105,650 2,467 Corporate debt securities 1 2,677 31 0 0 0 1 2,677 31 Government agency collateralized mortgage obligations 0 0 0 2 2 0 2 2 0 Total available-for-sale investment portfolio 268 $ 637,887 $ 4,840 17 $ 21,790 $ 830 285 $ 659,677 $ 5,670
Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity	The amortized cost and estimated fair value of debt securities at September 30, 2017, 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 $ 43,083 $ 43,270 Due after one through five years 1,507,979 1,531,059 Due after five years through ten years 832,917 852,985 Due after ten years 200,314 207,448 Subtotal 2,584,293 2,634,762 Government agency mortgage-backed securities 342,838 344,922 Government agency collateralized mortgage obligations 93,922 94,049 Total $ 3,021,053 $ 3,073,733

LOANS (Tables)

LOANS (Tables)	9 Months Ended
	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Schedule of Loans Receivable, Net	The balances of these classes are summarized as follows: (000's omitted) September 3 0 2017 December 31, 2016 Consumer mortgage $ 2,206,527 $ 1,819,701 Business lending 2,458,981 1,490,076 Consumer indirect 1,034,716 1,044,972 Consumer direct 183,898 191,815 Home equity 424,598 401,998 Gross loans, including deferred origination costs 6,308,720 4,948,562 Allowance for loan losses (47,983 ) (47,233 ) Loans, net of allowance for loan losses $ 6,260,737 $ 4,901,329
Schedule of 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, 2016 $ 498 Accretion recognized, year-to-date (451 ) Net reclassification to accretable from non-accretable 511 Merchants acquisition 758 Balance at September 30, 2017 $ 1,316
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 September 30, 2017: Legacy Loans (000’s omitted) Past Due 30 – 89 Days 90+ Days Past Due and Still Accruing Nonaccrual Total Past Due Current Total Loans Consumer mortgage $ 11,312 $ 1,275 $ 10,454 $ 23,041 $ 1,695,834 $ 1,718,875 Business lending 8,982 79 3,153 12,214 1,330,222 1,342,436 Consumer indirect 13,729 167 0 13,896 997,402 1,011,298 Consumer direct 1,506 67 0 1,573 175,823 177,396 Home equity 877 1 1,462 2,340 315,918 318,258 Total $ 36,406 $ 1,589 $ 15,069 $ 53,064 $ 4,515,199 $ 4,568,263 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 Consumer mortgage $ 1,949 $ 230 $ 3,526 $ 5,705 $ 0 $ 481,947 $ 487,652 Business lending 3,493 0 1,570 5,063 13,594 1,097,888 1,116,545 Consumer indirect 198 0 0 198 0 23,220 23,418 Consumer direct 131 2 0 133 0 6,369 6,502 Home equity 763 40 1,345 2,148 0 104,192 106,340 Total $ 6,534 $ 272 $ 6,441 $ 13,247 $ 13,594 $ 1,713,616 $ 1,740,457 (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, 2016: Legacy Loans (000’s omitted) Past Due 30 – 89 Days 90+ Days Past Due and Still Accruing Nonaccrual Total Past Due Current Total Loans Consumer mortgage $ 11,379 $ 1,180 $ 11,352 $ 23,911 $ 1,635,849 $ 1,659,760 Business lending 3,921 145 3,811 7,877 1,269,789 1,277,666 Consumer indirect 13,883 166 0 14,049 1,000,776 1,014,825 Consumer direct 1,549 58 0 1,607 180,315 181,922 Home equity 1,250 414 1,437 3,101 315,928 319,029 Total $ 31,982 $ 1,963 $ 16,600 $ 50,545 $ 4,402,657 $ 4,453,202 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 Consumer mortgage $ 1,539 $ 205 $ 2,332 $ 4,076 $ 0 $ 155,865 $ 159,941 Business lending 528 0 1,252 1,780 5,553 205,077 212,410 Consumer indirect 231 3 0 234 0 29,913 30,147 Consumer direct 231 0 0 231 0 9,662 9,893 Home equity 778 905 435 2,118 0 80,851 82,969 Total $ 3,307 $ 1,113 $ 4,019 $ 8,439 $ 5,553 $ 481,368 $ 495,360 (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.
Summary of Non-Business Impaired Loans	All loan classes are collectively evaluated for impairment except business lending, as described in Note C. A summary of individually evaluated impaired loans as of September 30, 2017 and December 31, 2016 follows: (000’s omitted) September 30, 2017 December 31, 2016 Loans with allowance allocation $ 0 $ 1,109 Loans without allowance allocation 907 556 Unpaid principal balance 907 1,665 Contractual balance 910 3,340 Allowance for loan loss allocated 0 477
Troubled Debt Restructurings on Financing Receivables	Information regarding TDRs as of September 30, 2017 and December 31, 2016 is as follows: September 30, 2017 December 31, 2016 (000’s omitted) Nonaccrual Accruing Total Nonaccrual Accruing Total # Amount # Amount # Amount # Amount # Amount # Amount Consumer mortgage 45 $ 2,131 47 $ 1,940 92 $ 4,071 36 $ 1,520 45 $ 1,956 81 $ 3,476 Business lending 9 453 5 383 14 836 6 91 5 690 11 781 Consumer indirect 0 0 70 839 70 839 0 0 78 771 78 771 Consumer direct 0 0 23 62 23 62 0 0 23 65 23 65 Home equity 11 223 7 207 18 430 14 221 7 216 21 437 Total 65 $ 2,807 152 $ 3,431 217 $ 6,238 56 $ 1,832 158 $ 3,698 214 $ 5,530 The following table presents information related to loans modified in a TDR during the three months and nine months ended September 30, 2017 and 2016. Of the loans noted in the table below, all loans for the three months and nine months ended September 30, 2017 and 2016 were modified due to a Chapter 7 bankruptcy as described previously. The financial effects of these restructurings were immaterial. Three Months Ended September 30, 2017 Three Months Ended September 30, 2016 (000’s omitted) Number of loans modified Outstanding Balance Number of loans modified Outstanding Balance Consumer mortgage 8 $ 540 2 $ 206 Business lending 1 51 0 0 Consumer indirect 8 181 9 89 Consumer direct 1 1 0 0 Home equity 1 8 0 0 Total 19 $ 781 11 $ 295 Nine Months Ended September 30, 2017 Nine Months Ended September 30, 2016 (000’s omitted) Number of loans modified Outstanding Balance Number of loans modified Outstanding Balance Consumer mortgage 15 $ 1,040 9 $ 787 Business lending 4 414 1 29 Consumer indirect 22 323 27 392 Consumer direct 4 7 1 51 Home equity 3 106 3 48 Total 48 $ 1,890 41 $ 1,307
Schedule of Allowance for Loan Losses by Class	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) Consumer Mortgage Business Lending Consumer Indirect Consumer Direct Home Equity Unallocated Acquired Impaired Total Beginning balance $ 10,197 $ 17,230 $ 13,918 $ 2,945 $ 2,242 $ 856 $ 63 $ 47,451 Charge-offs (198 ) (124 ) (2,328 ) (574 ) 0 0 0 (3,224 ) Recoveries 24 127 1,058 221 12 0 0 1,442 Provision 280 399 1,130 426 (52 ) 142 (11 ) 2,314 Ending balance $ 10,303 $ 17,632 $ 13,778 $ 3,018 $ 2,202 $ 998 $ 52 $ 47,983 Three Months Ended (000’s omitted) Consumer Mortgage Business Lending Consumer Indirect Consumer Direct Home Equity Unallocated Acquired Impaired Total Beginning balance $ 9,853 $ 16,949 $ 13,215 $ 3,020 $ 2,500 $ 850 $ 139 $ 46,526 Charge-offs (202 ) (284 ) (2,037 ) (395 ) (6 ) 0 0 (2,924 ) Recoveries 12 220 892 246 27 0 0 1,397 Provision 305 (283 ) 1,503 170 10 85 0 1,790 Ending balance $ 9,968 $ 16,602 $ 13,573 $ 3,041 $ 2,531 $ 935 $ 139 $ 46,789 Nine Months Ended (000’s omitted) Consumer Mortgage Business Lending Consumer Indirect Consumer Direct Home Equity Unallocated Acquired Impaired Total Beginning balance $ 10,094 $ 17,220 $ 13,782 $ 2,979 $ 2,399 $ 651 $ 108 $ 47,233 Charge-offs (541 ) (1,062 ) (5,969 ) (1,463 ) (228 ) 0 (184 ) (9,447 ) Recoveries 42 481 3,379 648 44 0 0 4,594 Provision 708 993 2,586 854 (13 ) 347 128 5,603 Ending balance $ 10,303 $ 17,632 $ 13,778 $ 3,018 $ 2,202 $ 998 $ 52 $ 47,983 Nine Months Ended (000’s omitted) Consumer Mortgage Business Lending Consumer Indirect Consumer Direct Home Equity Unallocated Acquired Impaired Total Beginning balance $ 10,198 $ 15,749 $ 12,422 $ 2,997 $ 2,666 $ 1,201 $ 168 $ 45,401 Charge-offs (445 ) (1,263 ) (5,439 ) (1,246 ) (142 ) 0 (26 ) (8,561 ) Recoveries 96 511 3,146 705 55 0 0 4,513 Provision 119 1,605 3,444 585 (48 ) (266 ) (3 ) 5,436 Ending balance $ 9,968 $ 16,602 $ 13,573 $ 3,041 $ 2,531 $ 935 $ 139 $ 46,789
Business Lending [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Schedule of Loans by Credit Quality Indicator	The following table shows the amount of business lending loans by credit quality category: September 30, 2017 December 31, 2016 (000’s omitted) Legacy Acquired Total Legacy Acquired Total Pass $ 1,122,422 $ 1,027,919 $ 2,150,341 $ 1,051,005 $ 162,165 $ 1,213,170 Special mention 126,928 34,988 161,916 135,602 29,690 165,292 Classified 93,086 40,044 133,130 90,585 15,002 105,587 Doubtful 0 0 0 474 0 474 Acquired impaired 0 13,594 13,594 0 5,553 5,553 Total $ 1,342,436 $ 1,116,545 $ 2,458,981 $ 1,277,666 $ 212,410 $ 1,490,076
All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Schedule of Loans by Credit Quality Indicator	The following table details the balances in all other loan categories at September 30, 2017: Legacy Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 1,707,146 $ 1,011,131 $ 177,329 $ 316,795 $ 3,212,401 Nonperforming 11,729 167 67 1,463 13,426 Total $ 1,718,875 $ 1,011,298 $ 177,396 $ 318,258 $ 3,225,827 Acquired Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 483,896 $ 23,418 $ 6,500 $ 104,955 $ 618,769 Nonperforming 3,756 0 2 1,385 5,143 Total $ 487,652 $ 23,418 $ 6,502 $ 106,340 $ 623,912 The following table details the balances in all other loan categories at December 31, 2016: Legacy Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 1,647,228 $ 1,014,659 $ 181,864 $ 317,178 $ 3,160,929 Nonperforming 12,532 166 58 1,851 14,607 Total $ 1,659,760 $ 1,014,825 $ 181,922 $ 319,029 $ 3,175,536 Acquired Loans (000’s omitted) Consumer Mortgage Consumer Indirect Consumer Direct Home Equity Total Performing $ 157,404 $ 30,144 $ 9,893 $ 81,629 $ 279,070 Nonperforming 2,537 3 0 1,340 3,880 Total $ 159,941 $ 30,147 $ 9,893 $ 82,969 $ 282,950

GOODWILL AND IDENTIFIABLE INT28

GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS (Tables)	9 Months Ended
	Sep. 30, 2017
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: September 30, 2017 December 31, 2016 (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 $ (36,101 ) $ 26,801 $ 39,688 $ (32,581 ) $ 7,107 Other intangibles 83,767 $ (17,718 ) 66,049 17,853 (9,258 ) 8,595 Total amortizing intangibles $ 146,669 $ (53,819 ) $ 92,850 $ 57,541 $ (41,839 ) $ 15,702
Estimated Aggregate Amortization Expense	The estimated aggregate amortization expense for each of the five succeeding fiscal years ended December 31 is as follows: (000's omitted) Oct - Dec 2017 $ 4,904 2018 17,259 2019 14,502 2020 12,043 2021 10,288 Thereafter 33,854 Total $ 92,850
Components of Goodwill	Shown below are the components of the Company’s goodwill at December 31, 2016 and September 30, 2017: (000’s omitted) December 31, 2016 Activity September 30, 2017 Goodwill $ 469,966 $ 266,363 $ 736,329 Accumulated impairment $ (4,824 ) $ 0 $ (4,824 ) Goodwill, net $ 465,142 $ 266,363 $ 731,505

MANDATORILY REDEEMABLE PREFER29

MANDATORILY REDEEMABLE PREFERRED SECURITIES (Tables)	9 Months Ended
	Sep. 30, 2017
MANDATORILY REDEEMABLE PREFERRED SECURITIES [Abstract]
Terms of Preferred Securities for Each Trust	The terms of the preferred securities of each trust are as follows: Trust Issuance Date Par Amount Interest Rate Maturity Date Call Price CST III 7/31/2001 $24.5 million 3 month LIBOR plus 3.58% (4.89%) 7/31/2031 Par CCT IV 12/8/2006 $75.0 million 3 month LIBOR plus 1.65% (2.97%) 12/15/2036 Par MBVT I 12/15/2004 $20.6 million 3 month LIBOR plus 1.95% (3.27%) 12/31/2034 Par

BENEFIT PLANS (Tables)

BENEFIT PLANS (Tables)	9 Months Ended
	Sep. 30, 2017
BENEFIT PLANS [Abstract]
Net Periodic Benefit Cost	The net periodic benefit cost for the three and nine months ended September 30, 2017 and 2016 is as follows: Pension Benefits Post-retirement Benefits Three Months Ended September 30, Nine Months Ended September 30, Three Months Ended September 30, Nine Months Ended September 30, (000's omitted) 2017 2016 2017 2016 2017 2016 2017 2016 Service cost $ 1,037 $ 1,027 $ 3,143 $ 3,079 $ 0 $ 0 $ 0 $ 0 Interest cost 1,453 1,406 4,265 4,218 19 20 57 61 Expected return on plan assets (3,448 ) (2,961 ) (9,977 ) (8,882 ) 0 0 0 0 Amortization of unrecognized net loss 148 377 619 1,131 2 (1 ) 6 (4 ) Amortization of prior service cost 13 11 43 33 (45 ) (45 ) (134 ) (134 ) Net periodic benefit cost (income) $ (797 ) $ (140 ) $ (1,907 ) $ (421 ) $ (24 ) $ (26 ) $ (71 ) $ (77 )

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2017
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 and nine months ended September 30, 2017 and 2016: Three Months Ended September 30, Nine Months Ended September 30, (000's omitted, except per share data) 2017 2016 2017 2016 Net income $ 35,243 $ 27,160 $ 78,691 $ 77,420 Income attributable to unvested stock-based compensation awards (164 ) (157 ) (387 ) (398 ) Income available to common shareholders $ 35,079 $ 27,003 $ 78,304 $ 77,022 Weighted-average common shares outstanding – basic 50,703 44,184 48,189 44,023 Basic earnings per share $ 0.69 $ 0.61 $ 1.62 $ 1.75 Net income $ 35,243 $ 27,160 $ 78,691 $ 77,420 Income attributable to unvested stock-based compensation awards (164 ) (157 ) (387 ) (398 ) Income available to common shareholders $ 35,079 $ 27,003 $ 78,304 $ 77,022 Weighted-average common shares outstanding – basic 50,703 44,184 48,189 44,023 Assumed exercise of stock options 585 394 640 359 Weighted-average common shares outstanding – diluted 51,288 44,578 48,829 44,382 Diluted earnings per share $ 0.68 $ 0.61 $ 1.60 $ 1.74

COMMITMENTS, CONTINGENT LIABI32

COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS (Tables)	9 Months Ended
	Sep. 30, 2017
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) September 30, 2017 December 31, 2016 Commitments to extend credit $ 1,038,125 $ 773,442 Standby letters of credit 24,058 22,656 Total $ 1,062,183 $ 796,098

FAIR VALUE (Tables)

FAIR VALUE (Tables)	9 Months Ended
	Sep. 30, 2017
FAIR VALUE [Abstract]
Summary of 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. September 30, 2017 (000's omitted) Level 1 Level 2 Level 3 Total Fair Value Available-for-sale investment securities: U.S. Treasury and agency securities $ 1,927,872 $ 146,269 $ 0 $ 2,074,141 Obligations of state and political subdivisions 0 557,959 0 557,959 Government agency mortgage-backed securities 0 344,922 0 344,922 Corporate debt securities 0 2,662 0 2,662 Government agency collateralized mortgage obligations 0 94,049 0 94,049 Marketable equity securities 527 0 0 527 Total available-for-sale investment securities 1,928,399 1,145,861 0 3,074,260 Mortgage loans held for sale 0 1,268 0 1,268 Commitments to originate real estate loans for sale 0 0 152 152 Forward sales commitments 0 (44 ) 0 (44 ) Interest rate swap agreements asset 0 1,102 0 1,102 Interest rate swap agreements liability 0 (890 ) 0 (890 ) Total $ 1,928,399 $ 1,147,297 $ 152 $ 3,075,848 December 31, 2016 (000's omitted) Level 1 Level 2 Level 3 Total Fair Value Available-for-sale investment securities: U.S. Treasury and agency securities $ 1,902,762 $ 0 $ 0 $ 1,902,762 Obligations of state and political subdivisions 0 594,990 0 594,990 Government agency mortgage-backed securities 0 235,230 0 235,230 Corporate debt securities 0 5,687 0 5,687 Government agency collateralized mortgage obligations 0 9,535 0 9,535 Marketable equity securities 452 0 0 452 Total available-for-sale investment securities 1,903,214 845,442 0 2,748,656 Mortgage loans held for sale 0 2,416 0 2,416 Commitments to originate real estate loans for sale 0 0 54 54 Forward sales commitments 0 3 0 3 Total $ 1,903,214 $ 847,861 $ 54 $ 2,751,129
Changes in Level 3 Assets Measured at Fair Value on a Recurring Basis	The changes in Level 3 assets measured at fair value on a recurring basis are summarized in the following tables: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (000's omitted) Commitments to Originate Real Estate Loans for Sale Commitments to Originate Real Estate Loans for Sale Commitments to Originate Real Estate Loans for Sale Commitments to Originate Real Estate Loans for Sale Beginning balance $ 179 $ 361 $ 54 $ 117 Total losses included in earnings (1) (179 ) (361 ) (347 ) (760 ) Commitments to originate real estate loans held for sale, net 152 474 445 1,117 Ending balance $ 152 $ 474 $ 152 $ 474
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. September 30, 2017 December 31, 2016 (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 $ 0 $ 0 $ 0 $ 0 $ 633 $ 633 Other real estate owned 0 0 1,873 1,873 0 0 1,966 1,966 Total $ 0 $ 0 $ 1,873 $ 1,873 $ 0 $ 0 $ 2,599 $ 2,599
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 September 30, 2017 Valuation Technique Significant Unobservable Inputs Significant Unobservable Input Range (Weighted Average) Other real estate owned $ 1,873 Fair Value of Collateral Estimated cost of disposal/market adjustment 9.0% - 65.9% (30.3 %) Commitments to originate real estate loans for sale 152 Discounted cash flow Embedded servicing value 1 % (000's omitted) Fair Value at December 31, 2016 Valuation Technique Significant Unobservable Inputs Significant Unobservable Input Range (Weighted Average) Other real estate owned $ 1,966 Fair value of collateral Estimated cost of disposal/market adjustment 9.0% - 97.0% (29.6 %) Impaired loans 633 Fair value of collateral Estimated cost of disposal/market adjustment 15.0% - 50.0% (36.5 %) Commitments to originate real estate loans for sale 54 Discounted cash flow Embedded servicing value 1 %
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 September 30, 2017 and December 31, 2016 are as follows: September 30, 2017 December 31, 2016 (000's omitted) Carrying Value Fair Value Carrying Value Fair Value Financial assets: Net loans $ 6,260,737 $ 6,321,781 $ 4,901,329 $ 4,935,140 Financial liabilities: Deposits 8,605,990 8,592,459 7,075,954 7,071,191 Short-term borrowings 0 0 146,200 146,200 Securities sold under agreement to repurchase, short-term 310,703 310,703 0 0 Other long-term debt 3,586 3,568 0 0 Subordinated debt held by unconsolidated subsidiary trusts 122,808 122,808 102,170 90,144

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2017
SEGMENT INFORMATION [Abstract]
Schedule of 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 September 30, 2017 Net interest income $ 84,227 $ 104 $ 64 $ 0 $ 84,395 Provision for loan losses 2,314 0 0 0 2,314 Noninterest revenues 20,120 21,207 12,298 (684 ) 52,941 Amortization of intangible assets 1,796 2,323 830 0 4,949 Acquisition expenses 534 11 35 0 580 Other operating expenses 56,926 12,788 9,217 (684 ) 78,247 Income before income taxes $ 42,777 $ 6,189 $ 2,280 $ 0 $ 51,246 Assets $ 10,613,065 $ 226,812 $ 77,802 $ (67,461 ) $ 10,850,218 Goodwill $ 629,153 $ 84,448 $ 17,904 $ 0 $ 731,505 Three Months Ended September 30, 2016 Net interest income $ 68,375 $ 39 $ 49 $ 0 $ 68,463 Provision for loan losses 1,790 0 0 0 1,790 Noninterest revenues 17,756 11,680 11,139 (623 ) 39,952 Amortization of intangible assets 665 96 598 0 1,359 Acquisition expenses 2 0 0 0 2 Other operating expenses 47,736 9,020 8,732 (623 ) 64,865 Income before income taxes $ 35,938 $ 2,603 $ 1,858 $ 0 $ 40,399 Assets $ 8,658,308 $ 36,706 $ 72,147 $ (39,415 ) $ 8,727,746 Goodwill $ 440,870 $ 8,019 $ 16,253 $ 0 $ 465,142 (000's omitted) Banking Employee Benefit Services All Other Eliminations Consolidated Total Nine Months Ended September 30, 2017 Net interest income $ 229,233 $ 276 $ 189 $ 0 $ 229,698 Provision for loan losses 5,603 0 0 0 5,603 Noninterest revenues 54,049 59,961 36,510 (2,035 ) 148,485 Amortization of intangible assets 3,520 6,256 2,204 0 11,980 Acquisition expenses 23,784 1,190 218 0 25,192 Other operating expenses 160,311 37,225 27,557 (2,035 ) 223,058 Income before income taxes $ 90,064 $ 15,566 $ 6,720 $ 0 $ 112,350 Nine Months Ended September 30, 2016 Net interest income $ 203,394 $ 117 $ 139 $ 0 $ 203,650 Provision for loan losses 5,436 0 0 0 5,436 Noninterest revenues 49,663 36,137 32,989 (1,784 ) 117,005 Amortization of intangible assets 2,075 326 1,803 0 4,204 Acquisition expenses 101 0 241 0 342 Other operating expenses 143,781 27,899 25,809 (1,784 ) 195,705 Income before income taxes $ 101,664 $ 8,029 $ 5,275 $ 0 $ 114,968

ACQUISITIONS (Details)

ACQUISITIONS (Details) shares in Thousands, $ in Millions	May 12, 2017USD ($)BranchLocationshares	Feb. 03, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Sep. 30, 2017USD ($)
Business Acquisition [Line Items]
Increase (decrease) in other assets as a result of reclassification and adjustment			$ 5.5	$ (2.7)
Increase (decrease) in other liabilities as a result of reclassification and adjustment			6.6	(2.4)
Increase in investments as a result of updated information not available at the time of acquisition			0.2
Decrease in loans as a result of an adjustment to the valuation of acquired impaired loans			(0.6)
Increase in premises and equipment as a result of updated appraisal information not available at the time of acquisition			3.6
Merchants Bancshares, Inc. [Member]
Business Acquisition [Line Items]
Issuance of common shares (in shares) | shares	4,680
Assets acquired	$ 1,990
Revenues earned			16.8		$ 25.8
Expenses incurred			7.5		11.5
Increase (decrease) in goodwill as a result of fair value adjustment			(2)
Merchants Bancshares, Inc. [Member] | VERMONT [Member]
Business Acquisition [Line Items]
Number of branch locations added upon merger | Branch	31
Merchants Bancshares, Inc. [Member] | MASSACHUSETTS [Member]
Business Acquisition [Line Items]
Number of branch locations added upon merger | Location	1
Northeast Retirement Services, Inc. [Member]
Business Acquisition [Line Items]
Tangible assets, net		$ 36.1
Factor of straight-line rate of depreciation used in declining balance depreciation method		150.00%
Period of amortization		10 years
Deferred tax liability		$ 24.2
Revenues earned			8.7		22.1
Expenses incurred			5.8		$ 15.1
Increase (decrease) in goodwill as a result of fair value adjustment			$ (0.1)	$ 0.3

ACQUISITIONS, Estimated Fair Va

ACQUISITIONS, Estimated Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands		May 12, 2017	Feb. 03, 2017	Jan. 04, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Consideration paid [Abstract]
Cash					$ 105,402	$ 575
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Goodwill					731,505	$ 465,142	$ 465,142
NRS [Member]
Consideration paid [Abstract]
Cash			$ 70,073
Community Bank System, Inc. common stock			78,483
Total net consideration paid			148,556
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Cash and cash equivalents			11,063
Investment securities			20,294
Loans			0
Premises and equipment			411
Accrued interest receivable			72
Other assets			8,088
Deposits			0
Other liabilities			(28,002)
Short-term advances			0
Securities sold under agreement to repurchase, short-term			0
Long-term debt			0
Subordinated debt held by unconsolidated subsidiary trusts			0
Total identifiable assets, net			72,126
Goodwill			76,430
NRS [Member] | Core Deposits [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Intangibles			0
NRS [Member] | Other Intangibles [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Intangibles			$ 60,200
Merchants Bancshares, Inc. [Member]
Consideration paid [Abstract]
Cash		$ 82,898
Community Bank System, Inc. common stock		262,254
Total net consideration paid		345,152
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Cash and cash equivalents		40,730
Investment securities		370,648
Loans		1,488,680
Premises and equipment		16,608
Accrued interest receivable		4,773
Other assets		51,849
Deposits		(1,448,406)
Other liabilities		(11,774)
Short-term advances		(80,000)
Securities sold under agreement to repurchase, short-term		(278,076)
Long-term debt		(3,615)
Subordinated debt held by unconsolidated subsidiary trusts		(20,619)
Total identifiable assets, net		156,869
Goodwill		188,283
Merchants Bancshares, Inc. [Member] | Core Deposits [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Intangibles		23,214
Merchants Bancshares, Inc. [Member] | Other Intangibles [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Intangibles		$ 2,857
WJL Agencies Inc [Member]
Consideration paid [Abstract]
Cash				$ 575
Community Bank System, Inc. common stock				0
Total net consideration paid				575
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Cash and cash equivalents				0
Investment securities				0
Loans				0
Premises and equipment				0
Accrued interest receivable				0
Other assets				0
Deposits				0
Other liabilities				0
Short-term advances				0
Securities sold under agreement to repurchase, short-term				0
Long-term debt				0
Subordinated debt held by unconsolidated subsidiary trusts				0
Total identifiable assets, net				288
Goodwill				287
WJL Agencies Inc [Member] | Core Deposits [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Intangibles				0
WJL Agencies Inc [Member] | Other Intangibles [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Intangibles				$ 288
Other [Member]
Consideration paid [Abstract]
Cash	[1]				4,224
Community Bank System, Inc. common stock	[1]				0
Total net consideration paid	[1]				4,224
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Cash and cash equivalents	[1]				0
Investment securities	[1]				0
Loans	[1]				0
Premises and equipment	[1]				27
Accrued interest receivable	[1]				0
Other assets	[1]				272
Deposits	[1]				0
Other liabilities	[1]				(582)
Short-term advances	[1]				0
Securities sold under agreement to repurchase, short-term	[1]				0
Long-term debt	[1]				0
Subordinated debt held by unconsolidated subsidiary trusts	[1]				0
Total identifiable assets, net	[1]				2,574
Goodwill	[1]				1,650
Other [Member] | Core Deposits [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Intangibles	[1]				0
Other [Member] | Other Intangibles [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Intangibles	[1]				2,857
Total [Member]
Consideration paid [Abstract]
Cash					157,195
Community Bank System, Inc. common stock					340,737
Total net consideration paid					497,932
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Cash and cash equivalents					51,793
Investment securities					390,942
Loans					1,488,680
Premises and equipment					17,046
Accrued interest receivable					4,845
Other assets					60,209
Deposits					(1,448,406)
Other liabilities					(40,358)
Short-term advances					(80,000)
Securities sold under agreement to repurchase, short-term					(278,076)
Long-term debt					(3,615)
Subordinated debt held by unconsolidated subsidiary trusts					(20,619)
Total identifiable assets, net					231,569
Goodwill					266,363
Total [Member] | Core Deposits [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Intangibles					23,214
Total [Member] | Other Intangibles [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed [Abstract]
Intangibles					$ 65,914
[1]	Includes amounts related to the BAS and Dryfoos acquisitions.

ACQUISITIONS, Summary of Loans

ACQUISITIONS, Summary of Loans Acquired (Details) - Merchants Bancshares, Inc. [Member] $ in Thousands	May 12, 2017USD ($)
Summary of loans acquired [Abstract]
Contractually required principal and interest at acquisition	$ 1,888,925
Contractual cash flows not expected to be collected	(20,547)
Expected cash flows at acquisition	1,868,378
Interest component of expected cash flows	(379,698)
Fair value of acquired loans	1,488,680
Acquired Impaired Loans [Member]
Summary of loans acquired [Abstract]
Contractually required principal and interest at acquisition	16,351
Contractual cash flows not expected to be collected	(5,794)
Expected cash flows at acquisition	10,557
Interest component of expected cash flows	(758)
Fair value of acquired loans	9,799
Acquired Non-impaired Loans [Member]
Summary of loans acquired [Abstract]
Contractually required principal and interest at acquisition	1,872,574
Contractual cash flows not expected to be collected	(14,753)
Expected cash flows at acquisition	1,857,821
Interest component of expected cash flows	(378,940)
Fair value of acquired loans	$ 1,478,881

ACQUISITIONS, Intangible Asset,

ACQUISITIONS, Intangible Asset, Goodwill and Acquisition-related Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Summary of loans acquired [Abstract]
Merger and acquisition integration-related expenses	$ 580	$ 2	$ 25,192	$ 342
Merchants Bancshares, Inc. [Member] | Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			8 years
Merchants Bancshares, Inc. [Member] | Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			8 years
Benefits Advisory Service, Inc [Member] | Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			8 years
Benefits Advisory Service, Inc [Member] | Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			8 years
Dryfoos Insurance Agency, Inc [Member] | Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			8 years
Dryfoos Insurance Agency, Inc [Member] | Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			8 years
WJL Agencies Inc [Member] | Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			8 years
WJL Agencies Inc [Member] | Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life			8 years

ACQUISITIONS, Supplemental Pro

ACQUISITIONS, Supplemental Pro Forma Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Supplemental Pro Forma Financial Information [Abstract]
Acquisitions-related expenses	$ 500		$ 25,000
Total revenue, net of interest expense, pro forma	136,692	$ 135,026	407,735	$ 400,341
Net income, pro forma	$ 35,533	$ 32,706	$ 104,197	$ 78,557

ACCOUNTING POLICIES (Details)

ACCOUNTING POLICIES (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017USD ($)$ / shares	Sep. 30, 2016USD ($)$ / shares	Sep. 30, 2017USD ($)ComponentCalculationSegmentFactor$ / shares	Sep. 30, 2016USD ($)$ / shares
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of broad components used in allowance methodology | Component			2
Number of calculations used for general loan loss allocation | Calculation			2
Number of main loan segments | Segment			5
Period of historical net charge-off data for each loan class used in determining allowance level			36 months
Number of qualitative environmental factors used in qualitative calculation for loan loss allocation | Factor			8
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net income | $	$ 35,243	$ 27,160	$ 78,691	$ 77,420
Net income per diluted common share (in dollars per share) | $ / shares	$ 0.68	$ 0.61	$ 1.60	$ 1.74
Core Deposits [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset useful life (amortization period)			7 years
Core Deposits [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset useful life (amortization period)			20 years
Customer Relationships [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset useful life (amortization period)			7 years
Customer Relationships [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset useful life (amortization period)			20 years
Commercial Portfolio Segment [Member] | Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Threshold balance of loans individually evaluated for impairment | $	$ 500		$ 500
ASU 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net income | $	$ 300		$ 2,900
Net income per diluted common share (in dollars per share) | $ / shares			$ 0.05
ASU 2016-09 [Member] | Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net income per diluted common share (in dollars per share) | $ / shares	$ 0.01

INVESTMENT SECURITIES (Details)

INVESTMENT SECURITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Available-for-Sale Portfolio [Abstract]
Amortized cost	$ 3,021,304	$ 2,706,863
Gross unrealized gains	55,827	47,463
Gross unrealized losses	2,871	5,670
Fair value	3,074,260	2,748,656
Available For Sale Debt Securities Amortized Cost Basis [Abstract]
Amortized cost	3,021,053
Fair value	3,073,733
Other Securities [Abstract]
Amortized cost	50,958	35,736
Fair value	50,958	35,736
U.S. Treasury and Agency Securities [Member]
Available For Sale Debt Securities Amortized Cost Basis [Abstract]
Amortized cost	2,040,820	1,876,358
Gross unrealized gains	33,703	28,522
Gross unrealized losses	382	2,118
Fair value	2,074,141	1,902,762
Obligations of State and Political Subdivisions [Member]
Available For Sale Debt Securities Amortized Cost Basis [Abstract]
Amortized cost	540,810	582,655
Gross unrealized gains	17,175	13,389
Gross unrealized losses	26	1,054
Fair value	557,959	594,990
Government Agency Mortgage-Backed Securities [Member]
Available For Sale Debt Securities Amortized Cost Basis [Abstract]
Amortized cost	342,838	232,657
Gross unrealized gains	4,398	5,040
Gross unrealized losses	2,314	2,467
Fair value	344,922	235,230
Corporate Debt Securities [Member]
Available For Sale Debt Securities Amortized Cost Basis [Abstract]
Amortized cost	2,663	5,716
Gross unrealized gains	0	2
Gross unrealized losses	1	31
Fair value	2,662	5,687
Government Agency Collateralized Mortgage Obligations [Member]
Available For Sale Debt Securities Amortized Cost Basis [Abstract]
Amortized cost	93,922	9,225
Gross unrealized gains	275	310
Gross unrealized losses	148	0
Fair value	94,049	9,535
Marketable Equity Securities [Member]
Available For Sale Equity Securities Amortized Cost Basis [Abstract]
Amortized cost	251	252
Gross unrealized gains	276	200
Gross unrealized losses	0	0
Fair value	527	452
Federal Home Loan Bank Common Stock [Member]
Other Securities [Abstract]
Amortized cost	8,837	12,191
Fair value	8,837	12,191
Federal Reserve Bank Common Stock [Member]
Other Securities [Abstract]
Amortized cost	30,690	19,781
Fair value	30,690	19,781
Certificates of Deposit [Member]
Other Securities [Abstract]
Amortized cost	5,581	0
Fair value	5,581	0
Other Equity Securities [Member]
Other Securities [Abstract]
Amortized cost	5,850	3,764
Fair value	$ 5,850	$ 3,764

INVESTMENT SECURITIES, Investme

INVESTMENT SECURITIES, Investment Securities in a Continuous Unrealized Loss Position (Details) $ in Thousands	Sep. 30, 2017USD ($)Position	Dec. 31, 2016USD ($)Position
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	155	268
12 months or longer | Position	30	17
Total | Position	185	285
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 413,043	$ 637,887
12 months or longer	36,148	21,790
Total	449,191	659,677
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	1,601	4,840
12 months or longer	1,270	830
Total	$ 2,871	$ 5,670
U.S. Treasury and Agency Securities [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	24	13
12 months or longer | Position	0	0
Total | Position	24	13
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 201,051	$ 449,242
12 months or longer	0	0
Total	201,051	449,242
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	382	2,118
12 months or longer	0	0
Total	$ 382	$ 2,118
Obligations of State and Political Subdivisions [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	9	197
12 months or longer | Position	1	0
Total | Position	10	197
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 4,386	$ 102,106
12 months or longer	365	0
Total	4,751	102,106
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	21	1,054
12 months or longer	5	0
Total	$ 26	$ 1,054
Government Agency Mortgage-Backed Securities [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	94	57
12 months or longer | Position	27	15
Total | Position	121	72
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 142,538	$ 83,862
12 months or longer	35,781	21,788
Total	178,319	105,650
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	1,049	1,637
12 months or longer	1,265	830
Total	$ 2,314	$ 2,467
Corporate Debt Securities [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	0	0
Total | Position	1	1
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 2,662	$ 2,677
12 months or longer	0	0
Total	2,662	2,677
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	1	31
12 months or longer	0	0
Total	$ 1	$ 31
Government Agency Collateralized Mortgage Obligations [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	27	0
12 months or longer | Position	2	2
Total | Position	29	2
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 62,406	$ 0
12 months or longer	2	2
Total	62,408	2
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	148	0
12 months or longer	0	0
Total	$ 148	$ 0

INVESTMENT SECURITIES, Amortize

INVESTMENT SECURITIES, Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Available-for-Sale, Debt Maturities, Amortized Cost [Abstract]
Due in one year or less	$ 43,083
Due after one through five years	1,507,979
Due after five years through ten years	832,917
Due after ten years	200,314
Subtotal	2,584,293
Amortized cost	3,021,053
Available-for-Sale, Debt Maturities, Fair Value [Abstract]
Due in one year or less	43,270
Due after one through five years	1,531,059
Due after five years through ten years	852,985
Due after ten years	207,448
Subtotal	2,634,762
Fair value	3,073,733
Government Agency Mortgage-Backed Securities [Member]
Available-for-Sale, Debt Maturities, Amortized Cost [Abstract]
Without single maturity date	342,838
Amortized cost	342,838	$ 232,657
Available-for-Sale, Debt Maturities, Fair Value [Abstract]
Without single maturity date	344,922
Fair value	344,922	235,230
Government Agency Collateralized Mortgage Obligations [Member]
Available-for-Sale, Debt Maturities, Amortized Cost [Abstract]
Without single maturity date	93,922
Amortized cost	93,922	9,225
Available-for-Sale, Debt Maturities, Fair Value [Abstract]
Without single maturity date	94,049
Fair value	94,049	9,535
U.S. Treasury Securities [Member]
Available-for-Sale, Debt Maturities, Amortized Cost [Abstract]
Amortized cost	2,040,820	1,876,358
Available-for-Sale, Debt Maturities, Fair Value [Abstract]
Fair value	2,074,141	$ 1,902,762
Securities pledged as collateral for securities sold under agreement to repurchase	$ 310,700

LOANS, Loan Summary (Details)

LOANS, Loan Summary (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	$ 6,308,720		$ 4,948,562
Allowance for loan losses	(47,983)	$ (47,451)	(47,233)	$ (46,789)	$ (46,526)	$ (45,401)
Net loans	6,260,737		4,901,329
Credit impaired acquired loans, total balance due	21,000		6,600
Accretable discount related to credit impaired acquired loans [Roll forward]
Beginning Balance	498
Accretion recognized, year-to-date	(451)
Net reclassification to accretable from non-accretable	511
Merchants acquisition	758
Ending Balance	$ 1,316
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
Business Lending [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	$ 2,458,981		1,490,076
Home Equity [Member] | Maximum [Member]
Loans receivable, net [Abstract]
Typical contract term	30 years
Residential Portfolio Segment [Member] | Consumer Mortgage [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	$ 2,206,527		1,819,701
Allowance for loan losses	(10,303)	(10,197)	(10,094)	(9,968)	(9,853)	(10,198)
Commercial Portfolio Segment [Member] | Business Lending [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	2,458,981		1,490,076
Allowance for loan losses	(17,632)	(17,230)	(17,220)	(16,602)	(16,949)	(15,749)
Consumer Portfolio Segment [Member] | Consumer Indirect [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	1,034,716		1,044,972
Allowance for loan losses	(13,778)	(13,918)	(13,782)	(13,573)	(13,215)	(12,422)
Consumer Portfolio Segment [Member] | Consumer Direct [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	183,898		191,815
Allowance for loan losses	(3,018)	(2,945)	(2,979)	(3,041)	(3,020)	(2,997)
Consumer Portfolio Segment [Member] | Home Equity [Member]
Loans receivable, net [Abstract]
Gross loans, including deferred origination costs	424,598		401,998
Allowance for loan losses	$ (2,202)	$ (2,242)	$ (2,399)	$ (2,531)	$ (2,500)	$ (2,666)

LOANS, Credit Quality By Past D

LOANS, Credit Quality By Past Due Status (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Aged analysis of the company's loans [Abstract]
Total loans		$ 6,308,720	$ 4,948,562
Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		1,589	1,963
Nonaccrual		15,069	16,600
Total past due		53,064	50,545
Current		4,515,199	4,402,657
Total loans		4,568,263	4,453,202
Legacy Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		36,406	31,982
Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
90 + days past due and still accruing		272	1,113
Nonaccrual		6,441	4,019
Total past due		13,247	8,439
Acquired impaired	[1]	13,594	5,553
Current		1,713,616	481,368
Total loans		1,740,457	495,360
Acquired Loans [Member] | Past Due 30 - 89 Days [Member]
Aged analysis of the company's loans [Abstract]
Total past due		6,534	3,307
Consumer Mortgage [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		1,718,875	1,659,760
Consumer Mortgage [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		487,652	159,941
Business Lending [Member]
Aged analysis of the company's loans [Abstract]
Total loans		2,458,981	1,490,076
Business Lending [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		1,342,436	1,277,666
Business Lending [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		1,116,545	212,410
Consumer Indirect [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		1,011,298	1,014,825
Consumer Indirect [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		23,418	30,147
Consumer Direct [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		177,396	181,922
Consumer Direct [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		6,502	9,893
Home Equity [Member] | Legacy Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		318,258	319,029
Home Equity [Member] | Acquired Loans [Member]
Aged analysis of the company's loans [Abstract]
Total loans		106,340	82,969
Residential Portfolio Segment [Member] | Consumer Mortgage [Member]
Aged analysis of the company's loans [Abstract]
Total loans		2,206,527	1,819,701
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		1,275	1,180
Nonaccrual		10,454	11,352
Total past due		23,041	23,911
Current		1,695,834	1,635,849
Total loans		1,718,875	1,659,760
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		11,312	11,379
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		230	205
Nonaccrual		3,526	2,332
Total past due		5,705	4,076
Acquired impaired	[1]	0	0
Current		481,947	155,865
Total loans		487,652	159,941
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		1,949	1,539
Commercial Portfolio Segment [Member] | Business Lending [Member]
Aged analysis of the company's loans [Abstract]
Total loans		2,458,981	1,490,076
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		79	145
Nonaccrual		3,153	3,811
Total past due		12,214	7,877
Current		1,330,222	1,269,789
Total loans		1,342,436	1,277,666
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		8,982	3,921
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		0	0
Nonaccrual		1,570	1,252
Total past due		5,063	1,780
Acquired impaired	[1]	13,594	5,553
Current		1,097,888	205,077
Total loans		1,116,545	212,410
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		3,493	528
Consumer Portfolio Segment [Member] | Consumer Indirect [Member]
Aged analysis of the company's loans [Abstract]
Total loans		1,034,716	1,044,972
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		167	166
Nonaccrual		0	0
Total past due		13,896	14,049
Current		997,402	1,000,776
Total loans		1,011,298	1,014,825
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		13,729	13,883
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		0	3
Nonaccrual		0	0
Total past due		198	234
Acquired impaired	[1]	0	0
Current		23,220	29,913
Total loans		23,418	30,147
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		198	231
Consumer Portfolio Segment [Member] | Consumer Direct [Member]
Aged analysis of the company's loans [Abstract]
Total loans		183,898	191,815
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		67	58
Nonaccrual		0	0
Total past due		1,573	1,607
Current		175,823	180,315
Total loans		177,396	181,922
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		1,506	1,549
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		2	0
Nonaccrual		0	0
Total past due		133	231
Acquired impaired	[1]	0	0
Current		6,369	9,662
Total loans		6,502	9,893
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		131	231
Consumer Portfolio Segment [Member] | Home Equity [Member]
Aged analysis of the company's loans [Abstract]
Total loans		424,598	401,998
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		1	414
Nonaccrual		1,462	1,437
Total past due		2,340	3,101
Current		315,918	315,928
Total loans		318,258	319,029
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		877	1,250
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		40	905
Nonaccrual		1,345	435
Total past due		2,148	2,118
Acquired impaired	[1]	0	0
Current		104,192	80,851
Total loans		106,340	82,969
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		$ 763	$ 778
[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	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 6,308,720	$ 4,948,562
Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	4,568,263	4,453,202
Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,740,457	495,360
Business Lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	2,458,981	1,490,076
Business Lending [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,342,436	1,277,666
Business Lending [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,116,545	212,410
Business Lending [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	2,150,341	1,213,170
Business Lending [Member] | Pass [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,122,422	1,051,005
Business Lending [Member] | Pass [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,027,919	162,165
Business Lending [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	161,916	165,292
Business Lending [Member] | Special Mention [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	126,928	135,602
Business Lending [Member] | Special Mention [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	34,988	29,690
Business Lending [Member] | Classified [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	133,130	105,587
Business Lending [Member] | Classified [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	93,086	90,585
Business Lending [Member] | Classified [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	40,044	15,002
Business Lending [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	474
Business Lending [Member] | Doubtful [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	474
Business Lending [Member] | Doubtful [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Business Lending [Member] | Acquired Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	13,594	5,553
Business Lending [Member] | Acquired Impaired [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Business Lending [Member] | Acquired Impaired [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	13,594	5,553
All Other Loans [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	3,225,827	3,175,536
All Other Loans [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	623,912	282,950
All Other Loans [Member] | Performing [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	3,212,401	3,160,929
All Other Loans [Member] | Performing [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	618,769	279,070
All Other Loans [Member] | Nonperforming [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	13,426	14,607
All Other Loans [Member] | Nonperforming [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	5,143	3,880
Consumer Mortgage [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,718,875	1,659,760
Consumer Mortgage [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	487,652	159,941
Consumer Mortgage [Member] | Performing [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,707,146	1,647,228
Consumer Mortgage [Member] | Performing [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	483,896	157,404
Consumer Mortgage [Member] | Nonperforming [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	11,729	12,532
Consumer Mortgage [Member] | Nonperforming [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	3,756	2,537
Consumer Indirect [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,011,298	1,014,825
Consumer Indirect [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	23,418	30,147
Consumer Indirect [Member] | Performing [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,011,131	1,014,659
Consumer Indirect [Member] | Performing [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	23,418	30,144
Consumer Indirect [Member] | Nonperforming [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	167	166
Consumer Indirect [Member] | Nonperforming [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	3
Consumer Direct [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	177,396	181,922
Consumer Direct [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	6,502	9,893
Consumer Direct [Member] | Performing [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	177,329	181,864
Consumer Direct [Member] | Performing [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	6,500	9,893
Consumer Direct [Member] | Nonperforming [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	67	58
Consumer Direct [Member] | Nonperforming [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	2	0
Home Equity [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	318,258	319,029
Home Equity [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	106,340	82,969
Home Equity [Member] | Performing [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	316,795	317,178
Home Equity [Member] | Performing [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	104,955	81,629
Home Equity [Member] | Nonperforming [Member] | Legacy Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,463	1,851
Home Equity [Member] | Nonperforming [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 1,385	$ 1,340

LOANS, Summary of Impaired Loan

LOANS, Summary of Impaired Loans, Excluding Purchased Impaired (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Impaired loans [Abstract]
Loans with allowance allocation	$ 0	$ 1,109
Loans without allowance allocation	907	556
Unpaid principal balance	907	1,665
Contractual balance	910	3,340
Allowance for loan loss allocated	$ 0	$ 477

LOANS, Troubled Debt Restructur

LOANS, Troubled Debt Restructuring (TDR) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017USD ($)Loan	Sep. 30, 2016USD ($)Loan	Sep. 30, 2017USD ($)Loan	Sep. 30, 2016USD ($)Loan	Dec. 31, 2016USD ($)Loan
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	217		217		214
TDRs, amount	$ 6,238		$ 6,238		$ 5,530
Loans modified in TDR during the year, number | Loan	19	11	48	41
Loans modified in TDR during the year, amount	$ 781	$ 295	$ 1,890	$ 1,307
Maximum [Member]
Financing Receivable, Modifications [Line Items]
Threshold balance of TDR loans collectively included in general loan loss allocation and qualitative review	$ 500		$ 500
Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	65		65		56
TDRs, amount	$ 2,807		$ 2,807		$ 1,832
Accruing [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	152		152		158
TDRs, amount	$ 3,431		$ 3,431		$ 3,698
Residential Portfolio Segment [Member] | Consumer Mortgage [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	92		92		81
TDRs, amount	$ 4,071		$ 4,071		$ 3,476
Loans modified in TDR during the year, number | Loan	8	2	15	9
Loans modified in TDR during the year, amount	$ 540	$ 206	$ 1,040	$ 787
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	45		45		36
TDRs, amount	$ 2,131		$ 2,131		$ 1,520
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] | Accruing [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	47		47		45
TDRs, amount	$ 1,940		$ 1,940		$ 1,956
Commercial Portfolio Segment [Member] | Minimum [Member]
Financing Receivable, Modifications [Line Items]
Threshold balance of loans individually evaluated for impairment	$ 500		$ 500
Commercial Portfolio Segment [Member] | Business Lending [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	14		14		11
TDRs, amount	$ 836		$ 836		$ 781
Loans modified in TDR during the year, number | Loan	1	0	4	1
Loans modified in TDR during the year, amount	$ 51	$ 0	$ 414	$ 29
Commercial Portfolio Segment [Member] | Business Lending [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	9		9		6
TDRs, amount	$ 453		$ 453		$ 91
Commercial Portfolio Segment [Member] | Business Lending [Member] | Accruing [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	5		5		5
TDRs, amount	$ 383		$ 383		$ 690
Consumer Portfolio Segment [Member] | Consumer Indirect [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	70		70		78
TDRs, amount	$ 839		$ 839		$ 771
Loans modified in TDR during the year, number | Loan	8	9	22	27
Loans modified in TDR during the year, amount	$ 181	$ 89	$ 323	$ 392
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	0		0		0
TDRs, amount	$ 0		$ 0		$ 0
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] | Accruing [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	70		70		78
TDRs, amount	$ 839		$ 839		$ 771
Consumer Portfolio Segment [Member] | Consumer Direct [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	23		23		23
TDRs, amount	$ 62		$ 62		$ 65
Loans modified in TDR during the year, number | Loan	1	0	4	1
Loans modified in TDR during the year, amount	$ 1	$ 0	$ 7	$ 51
Consumer Portfolio Segment [Member] | Consumer Direct [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	0		0		0
TDRs, amount	$ 0		$ 0		$ 0
Consumer Portfolio Segment [Member] | Consumer Direct [Member] | Accruing [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	23		23		23
TDRs, amount	$ 62		$ 62		$ 65
Consumer Portfolio Segment [Member] | Home Equity [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	18		18		21
TDRs, amount	$ 430		$ 430		$ 437
Loans modified in TDR during the year, number | Loan	1	0	3	3
Loans modified in TDR during the year, amount	$ 8	$ 0	$ 106	$ 48
Consumer Portfolio Segment [Member] | Home Equity [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	11		11		14
TDRs, amount	$ 223		$ 223		$ 221
Consumer Portfolio Segment [Member] | Home Equity [Member] | Accruing [Member]
Financing Receivable, Modifications [Line Items]
TDRs, number | Loan	7		7		7
TDRs, amount	$ 207		$ 207		$ 216

LOANS, Allowance for Loan Losse

LOANS, Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Allowance for loan losses [Roll Forward]
Beginning balance	$ 47,451	$ 46,526	$ 47,233	$ 45,401
Charge-offs	(3,224)	(2,924)	(9,447)	(8,561)
Recoveries	1,442	1,397	4,594	4,513
Provision	2,314	1,790	5,603	5,436
Ending balance	47,983	46,789	47,983	46,789
Acquired Impaired [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	63	139	108	168
Charge-offs	0	0	(184)	(26)
Recoveries	0	0	0	0
Provision	(11)	0	128	(3)
Ending balance	52	139	52	139
Residential Portfolio Segment [Member] | Consumer Mortgage [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	10,197	9,853	10,094	10,198
Charge-offs	(198)	(202)	(541)	(445)
Recoveries	24	12	42	96
Provision	280	305	708	119
Ending balance	10,303	9,968	10,303	9,968
Commercial Portfolio Segment [Member] | Business Lending [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	17,230	16,949	17,220	15,749
Charge-offs	(124)	(284)	(1,062)	(1,263)
Recoveries	127	220	481	511
Provision	399	(283)	993	1,605
Ending balance	17,632	16,602	17,632	16,602
Consumer Portfolio Segment [Member] | Consumer Indirect [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	13,918	13,215	13,782	12,422
Charge-offs	(2,328)	(2,037)	(5,969)	(5,439)
Recoveries	1,058	892	3,379	3,146
Provision	1,130	1,503	2,586	3,444
Ending balance	13,778	13,573	13,778	13,573
Consumer Portfolio Segment [Member] | Consumer Direct [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	2,945	3,020	2,979	2,997
Charge-offs	(574)	(395)	(1,463)	(1,246)
Recoveries	221	246	648	705
Provision	426	170	854	585
Ending balance	3,018	3,041	3,018	3,041
Consumer Portfolio Segment [Member] | Home Equity [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	2,242	2,500	2,399	2,666
Charge-offs	0	(6)	(228)	(142)
Recoveries	12	27	44	55
Provision	(52)	10	(13)	(48)
Ending balance	2,202	2,531	2,202	2,531
Unallocated Financing Receivables [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	856	850	651	1,201
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	142	85	347	(266)
Ending balance	$ 998	$ 935	$ 998	$ 935

GOODWILL AND IDENTIFIABLE INT50

GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 146,669	$ 57,541
Accumulated amortization	(53,819)	(41,839)
Net carrying amount	92,850	15,702
Estimated aggregate amortization expense [Abstract]
Oct - Dec 2017	4,904
2,018	17,259
2,019	14,502
2,020	12,043
2,021	10,288
Thereafter	33,854
Net carrying amount	92,850	15,702
Components of goodwill [Abstract]
Goodwill	736,329	469,966
Goodwill, activity	266,363
Accumulated impairment	(4,824)	(4,824)
Accumulated impairment, activity	0
Goodwill, net	731,505	465,142	$ 465,142
Goodwill, net, activity	266,363
Core Deposit Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	62,902	39,688
Accumulated amortization	(36,101)	(32,581)
Net carrying amount	26,801	7,107
Estimated aggregate amortization expense [Abstract]
Net carrying amount	26,801	7,107
Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	83,767	17,853
Accumulated amortization	(17,718)	(9,258)
Net carrying amount	66,049	8,595
Estimated aggregate amortization expense [Abstract]
Net carrying amount	$ 66,049	$ 8,595

MANDATORILY REDEEMABLE PREFER51

MANDATORILY REDEEMABLE PREFERRED SECURITIES (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)Trust
Debt Instrument [Line Items]
Number of wholly owned, unconsolidated subsidiary trusts | Trust	3
Percent ownership of unconsolidated subsidiary trusts	100.00%
Preferred Debt [Member] | Community Statutory Trust III [Member]
Terms of preferred securities for each trust [Abstract]
Issuance date	Jul. 31, 2001
Par amount	$ 24.5
Variable interest rate basis	3 month LIBOR
Variable interest rate, basis spread	3.58%
Effective interest rate	4.89%
Maturity date	Jul. 31, 2031
Call price	Par
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
Variable interest rate, basis spread	1.65%
Effective interest rate	2.97%
Maturity date	Dec. 15, 2036
Call price	Par
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
Variable interest rate, basis spread	1.95%
Effective interest rate	3.27%
Maturity date	Dec. 31, 2034
Call price	Par

BENEFIT PLANS (Details)

BENEFIT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	May 12, 2017	Dec. 31, 2016
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Tax Status [Extensible List]	us-gaap:QualifiedPlanMember				us-gaap:QualifiedPlanMember
Unamortized actuarial gain							$ 1,900
Discount rate							4.40%	4.50%
Employer contributions			$ 2,900
Net periodic benefit cost [Abstract]
Service cost	$ 1,037			$ 1,027	$ 3,143	$ 3,079
Interest cost	1,453			1,406	4,265	4,218
Expected return on plan assets	(3,448)			(2,961)	(9,977)	(8,882)
Amortization of unrecognized net loss	148			377	619	1,131
Amortization of prior service cost	13			11	43	33
Net periodic benefit cost (income)	(797)			(140)	(1,907)	(421)
Post-retirement Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost	0			0	0	0
Interest cost	19			20	57	61
Expected return on plan assets	0			0	0	0
Amortization of unrecognized net loss	2			(1)	6	(4)
Amortization of prior service cost	(45)			(45)	(134)	(134)
Net periodic benefit cost (income)	$ (24)			$ (26)	$ (71)	$ (77)
Merchants Bancshares, Inc. [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 2,000

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
EARNINGS PER SHARE [Abstract]
Weighted-average anti-dilutive stock options outstanding (in shares)	200,000	0	100,000	300,000
Basic earnings per share [Abstract]
Net income	$ 35,243	$ 27,160	$ 78,691	$ 77,420
Income attributable to unvested stock-based compensation awards	(164)	(157)	(387)	(398)
Income available to common shareholders	$ 35,079	$ 27,003	$ 78,304	$ 77,022
Weighted-average common shares outstanding - basic (in shares)	50,703,000	44,184,000	48,189,000	44,023,000
Basic earnings per share (in dollars per share)	$ 0.69	$ 0.61	$ 1.62	$ 1.75
Diluted earnings per share [Abstract]
Net income	$ 35,243	$ 27,160	$ 78,691	$ 77,420
Income attributable to unvested stock-based compensation awards	(164)	(157)	(387)	(398)
Income available to common shareholders	$ 35,079	$ 27,003	$ 78,304	$ 77,022
Weighted-average common shares outstanding - basic (in shares)	50,703,000	44,184,000	48,189,000	44,023,000
Assumed exercise of stock options (in shares)	585,000	394,000	640,000	359,000
Weighted-average common shares outstanding - diluted (in shares)	51,288,000	44,578,000	48,829,000	44,382,000
Diluted earnings per share (in dollars per share)	$ 0.68	$ 0.61	$ 1.60	$ 1.74
Stock Repurchase Program [Abstract]
Number of common shares authorized to be repurchased (in shares)					2,200,000
Number of common shares repurchased (in shares)			0

COMMITMENTS, CONTINGENT LIABI54

COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount of commitments and contingencies	$ 1,062,183	$ 796,098
Minimum [Member]
Off-balance Sheet Risks, Disclosure Information [Line Items]
Range of reasonably possible losses for such matters in the aggregate, beyond the existing recorded liability	0
Maximum [Member]
Off-balance Sheet Risks, Disclosure Information [Line Items]
Range of reasonably possible losses for such matters in the aggregate, beyond the existing recorded liability	1,000
Commitments to Extend Credit [Member]
Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount of commitments and contingencies	1,038,125	773,442
Standby Letters of Credit [Member]
Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount of commitments and contingencies	$ 24,058	$ 22,656

FAIR VALUE, Financial Assets an

FAIR VALUE, Financial Assets and Liabilities Accounted for at Fair Value On a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	$ 3,074,260	$ 2,748,656
Recurring [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	3,074,260	2,748,656
Mortgage loans held for sale	1,268	2,416
Total	3,075,848	2,751,129
Recurring [Member] | Commitments to Originate Real Estate Loans for Sale [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	152	54
Recurring [Member] | Forward Sales Commitments [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	(44)	3
Recurring [Member] | Interest Rate Swap Agreements [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	1,102
Derivative liability	(890)
Recurring [Member] | U.S. Treasury and Agency Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	2,074,141	1,902,762
Recurring [Member] | Obligations of State and Political Subdivisions [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	557,959	594,990
Recurring [Member] | Government Agency Mortgage-Backed Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	344,922	235,230
Recurring [Member] | Corporate Debt Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	2,662	5,687
Recurring [Member] | Government Agency Collateralized Mortgage Obligations [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	94,049	9,535
Recurring [Member] | Marketable Equity Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	527	452
Recurring [Member] | Level 1 [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	1,928,399	1,903,214
Mortgage loans held for sale	0	0
Total	1,928,399	1,903,214
Recurring [Member] | Level 1 [Member] | Commitments to Originate Real Estate Loans for Sale [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	0	0
Recurring [Member] | Level 1 [Member] | Forward Sales Commitments [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	0	0
Recurring [Member] | Level 1 [Member] | Interest Rate Swap Agreements [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	0
Derivative liability	0
Recurring [Member] | Level 1 [Member] | U.S. Treasury and Agency Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	1,927,872	1,902,762
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 1 [Member] | Marketable Equity Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	527	452
Recurring [Member] | Level 2 [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	1,145,861	845,442
Mortgage loans held for sale	1,268	2,416
Total	1,147,297	847,861
Mortgage loans held for sale, at principal value	1,300
Recurring [Member] | Level 2 [Member] | Commitments to Originate Real Estate Loans for Sale [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	0	0
Recurring [Member] | Level 2 [Member] | Forward Sales Commitments [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	(44)	3
Recurring [Member] | Level 2 [Member] | Interest Rate Swap Agreements [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	1,102
Derivative liability	(890)
Recurring [Member] | Level 2 [Member] | U.S. Treasury and Agency Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	146,269	0
Recurring [Member] | Level 2 [Member] | Obligations of State and Political Subdivisions [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	557,959	594,990
Recurring [Member] | Level 2 [Member] | Government Agency Mortgage-Backed Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	344,922	235,230
Recurring [Member] | Level 2 [Member] | Corporate Debt Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	2,662	5,687
Recurring [Member] | Level 2 [Member] | Government Agency Collateralized Mortgage Obligations [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	94,049	9,535
Recurring [Member] | Level 2 [Member] | Marketable Equity Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	0	0
Recurring [Member] | Level 3 [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	0	0
Mortgage loans held for sale	0	0
Total	152	54
Recurring [Member] | Level 3 [Member] | Commitments to Originate Real Estate Loans for Sale [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	152	54
Recurring [Member] | Level 3 [Member] | Forward Sales Commitments [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	0	0
Recurring [Member] | Level 3 [Member] | Interest Rate Swap Agreements [Member]
Available-for-sale investment securities [Abstract]
Derivative asset	0
Derivative liability	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
Recurring [Member] | Level 3 [Member] | Marketable Equity Securities [Member]
Available-for-sale investment securities [Abstract]
Available-for-sale investment securities	$ 0	$ 0

FAIR VALUE, Unobservable Input

FAIR VALUE, Unobservable Input Reconciliation (Details) - Commitments to Originate Real Estate Loans for Sale [Member] - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Level 3 Assets Measured at Fair Value on a Recurring Basis [Abstract]
Beginning balance		$ 179	$ 361	$ 54	$ 117
Total losses included in earnings	[1]	(179)	(361)	(347)	(760)
Commitments to originate real estate loans held for sale, net		152	474	445	1,117
Ending balance		$ 152	$ 474	$ 152	$ 474
[1]	Amounts included in earnings associated with the commitments to originate real estate loans for sale are reported as a component of other banking services in the Consolidated Statement of Income.

FAIR VALUE, Assets and Liabilit

FAIR VALUE, Assets and Liabilities Measured on Nonrecurring Basis (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Fair Value Inputs [Abstract]
Valuation allowance	$ 0	$ 477
Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	$ 1,873	$ 1,966
Other Real Estate Owned [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Discount rate	9.00%	9.00%
Other Real Estate Owned [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Discount rate	65.90%	97.00%
Mortgage Servicing Rights [Member]
Fair Value Inputs [Abstract]
Valuation allowance	$ 0
Level 3 [Member] | Other Real Estate Owned [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Discount rate	9.00%
Level 3 [Member] | Other Real Estate Owned [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Discount rate	65.90%
Non-recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	$ 0	$ 633
Other real estate owned	1,873	1,966
Total	1,873	2,599
Non-recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Other real estate owned	0	0
Total	0	0
Non-recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Other real estate owned	0	0
Total	0	0
Non-recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	633
Other real estate owned	1,873	1,966
Total	$ 1,873	$ 2,599

FAIR VALUE, Significant Unobser

FAIR VALUE, Significant Unobservable Inputs (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Other Real Estate Owned [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	$ 1,873	$ 1,966
Other Real Estate Owned [Member] | Fair Value of Collateral [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated cost of disposal/market adjustment	9.00%	9.00%
Other Real Estate Owned [Member] | Fair Value of Collateral [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated cost of disposal/market adjustment	65.90%	97.00%
Other Real Estate Owned [Member] | Fair Value of Collateral [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated cost of disposal/market adjustment	30.30%	29.60%
Impaired Loans [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value		$ 633
Impaired Loans [Member] | Fair Value of Collateral [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated cost of disposal/market adjustment		15.00%
Impaired Loans [Member] | Fair Value of Collateral [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated cost of disposal/market adjustment		50.00%
Impaired Loans [Member] | Fair Value of Collateral [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated cost of disposal/market adjustment		36.50%
Commitments To Originate Real Estate Loans For Sale [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	$ 152	$ 54
Commitments To Originate Real Estate Loans For Sale [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Embedded servicing value	1.00%	1.00%

FAIR VALUE, Carrying Amounts an

FAIR VALUE, Carrying Amounts and Estimated Fair Values of Other Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Carrying Value [Member]
Financial assets [Abstract]
Net loans	$ 6,260,737	$ 4,901,329
Financial liabilities [Abstract]
Deposits	8,605,990	7,075,954
Short-term borrowings	0	146,200
Securities sold under agreement to repurchase, short-term	310,703	0
Other long-term debt	3,586	0
Subordinated debt held by unconsolidated subsidiary trusts	122,808	102,170
Fair Value [Member]
Financial assets [Abstract]
Net loans	6,321,781	4,935,140
Financial liabilities [Abstract]
Deposits	8,592,459	7,071,191
Short-term borrowings	0	146,200
Securities sold under agreement to repurchase, short-term	310,703	0
Other long-term debt	3,568	0
Subordinated debt held by unconsolidated subsidiary trusts	$ 122,808	$ 90,144

DERIVATIVE INSTRUMENTS (Details

DERIVATIVE INSTRUMENTS (Details) - Interest Rate Swap [Member] $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)
Derivative [Line Items]
Derivative, notional amount	$ 39.4
Derivative weighted average receive rate	3.12%
Derivative weighted average pay rate	3.84%
Weighted average maturity period	6 years 8 months 12 days
Other Assets [Member]
Derivative [Line Items]
Fair value of derivate assets	$ 0.9
Other Liabilities [Member]
Derivative [Line Items]
Fair value of derivate liability	0.9
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Derivative, notional amount	$ 7
Derivative weighted average receive rate	2.13%
Derivative weighted average pay rate	3.11%
Weighted average maturity period	15 years 9 months 18 days
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] | Other Assets [Member]
Derivative [Line Items]
Fair value of derivate assets	$ 0.2

SEGMENT INFORMATION (Details)

SEGMENT INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Information about reportable segments
Net interest income	$ 84,395	$ 68,463	$ 229,698	$ 203,650
Provision for loan losses	2,314	1,790	5,603	5,436
Noninterest revenues	52,941	39,952	148,485	117,005
Amortization of intangible assets	4,949	1,359	11,980	4,204
Acquisition expenses	580	2	25,192	342
Other operating expenses	78,247	64,865	223,058	195,705
Income before income taxes	51,246	40,399	112,350	114,968
Assets	10,850,218	8,727,746	10,850,218	8,727,746	$ 8,666,437
Goodwill	731,505	465,142	731,505	465,142	$ 465,142
Eliminations [Member]
Information about reportable segments
Net interest income	0	0	0	0
Provision for loan losses	0	0	0	0
Noninterest revenues	(684)	(623)	(2,035)	(1,784)
Amortization of intangible assets	0	0	0	0
Acquisition expenses	0	0	0	0
Other operating expenses	(684)	(623)	(2,035)	(1,784)
Income before income taxes	0	0	0	0
Assets	(67,461)	(39,415)	(67,461)	(39,415)
Goodwill	0	0	0	0
Banking [Member] | Operating Segments [Member]
Information about reportable segments
Net interest income	84,227	68,375	229,233	203,394
Provision for loan losses	2,314	1,790	5,603	5,436
Noninterest revenues	20,120	17,756	54,049	49,663
Amortization of intangible assets	1,796	665	3,520	2,075
Acquisition expenses	534	2	23,784	101
Other operating expenses	56,926	47,736	160,311	143,781
Income before income taxes	42,777	35,938	90,064	101,664
Assets	10,613,065	8,658,308	10,613,065	8,658,308
Goodwill	629,153	440,870	629,153	440,870
Employee Benefit Services [Member] | Operating Segments [Member]
Information about reportable segments
Net interest income	104	39	276	117
Provision for loan losses	0	0	0	0
Noninterest revenues	21,207	11,680	59,961	36,137
Amortization of intangible assets	2,323	96	6,256	326
Acquisition expenses	11	0	1,190	0
Other operating expenses	12,788	9,020	37,225	27,899
Income before income taxes	6,189	2,603	15,566	8,029
Assets	226,812	36,706	226,812	36,706
Goodwill	84,448	8,019	84,448	8,019
All Other [Member]
Information about reportable segments
Net interest income	64	49	189	139
Provision for loan losses	0	0	0	0
Noninterest revenues	12,298	11,139	36,510	32,989
Amortization of intangible assets	830	598	2,204	1,803
Acquisition expenses	35	0	218	241
Other operating expenses	9,217	8,732	27,557	25,809
Income before income taxes	2,280	1,858	6,720	5,275
Assets	77,802	72,147	77,802	72,147
Goodwill	$ 17,904	$ 16,253	$ 17,904	$ 16,253