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BENEFIT PLANS (Tables) | 12 Months Ended
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Dec. 31, 2017
BENEFIT PLANS [Abstract] |
Funded Status of Plans Reconciled with Amounts Reported in Consolidated Statements of Condition | Using a measurement date of December 31, the following table shows the funded status of the Company's plans reconciled with amounts reported in the Company's consolidated statements of condition:
|  | Pension Benefits |  |  | Post-retirement Benefits |
(000's omitted) |  | 2017 |  |  | 2016 |  |  | 2017 |  |  | 2016 |
Change in benefit obligation: |  |  |  |  |  |  |  |  |  |  |  |
Benefit obligation at the beginning of year |  | $ | 127,084 |  |  | $ | 127,134 |  |  | $ | 1,806 |  |  | $ | 1,918 |
Service cost |  |  | 4,181 |  |  |  | 4,106 |  |  |  | 0 |  |  |  | 0 |
Interest cost |  |  | 5,717 |  |  |  | 5,624 |  |  |  | 76 |  |  |  | 82 |
Plan amendment / acquisition |  |  | 11,646 |  |  |  | 22 |  |  |  | 0 |  |  |  | 0 |
Participant contributions |  |  | 0 |  |  |  | 0 |  |  |  | 467 |  |  |  | 516 |
Deferred actuarial loss/(gain) |  |  | 8,978 |  |  |  | (1,628 | ) |  |  | 245 |  |  |  | 174 |
Benefits paid |  |  | (10,156 | ) |  |  | (8,174 | ) |  |  | (809 | ) |  |  | (884 | )
Benefit obligation at end of year |  |  | 147,450 |  |  |  | 127,084 |  |  |  | 1,785 |  |  |  | 1,806 |
Change in plan assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair value of plan assets at beginning of year |  |  | 180,400 |  |  |  | 172,026 |  |  |  | 0 |  |  |  | 0 |
Actual return of plan assets |  |  | 22,954 |  |  |  | 14,402 |  |  |  | 0 |  |  |  | 0 |
Participant contributions |  |  | 0 |  |  |  | 0 |  |  |  | 467 |  |  |  | 516 |
Employer contributions |  |  | 9,839 |  |  |  | 2,146 |  |  |  | 342 |  |  |  | 368 |
Plan acquisition |  |  | 14,070 |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |
Benefits paid |  |  | (10,156 | ) |  |  | (8,174 | ) |  |  | (809 | ) |  |  | (884 | )
Fair value of plan assets at end of year |  |  | 217,107 |  |  |  | 180,400 |  |  |  | 0 |  |  |  | 0 |
Over/(Under) funded status at year end |  | $ | 69,657 |  |  | $ | 53,316 |  |  | $ | (1,785 | ) |  | $ | (1,806 | )
Amounts recognized in the consolidated statement of condition were: |
Other assets |  | $ | 81,000 |  |  | $ | 64,709 |  |  | $ | 0 |  |  | $ | 0 |
Other liabilities |  |  | (11,343 | ) |  |  | (11,393 | ) |  |  | (1,785 | ) |  |  | (1,806 | )
Amounts recognized in accumulated other comprehensive income (loss) (“AOCI”) were: |
Net loss |  | $ | 26,935 |  |  | $ | 28,323 |  |  | $ | 420 |  |  | $ | 183 |
Net prior service cost (credit) |  |  | 2,944 |  |  |  | 2,264 |  |  |  | (1,622 | ) |  |  | (1,801 | )
Pre-tax AOCI |  |  | 29,879 |  |  |  | 30,587 |  |  |  | (1,202 | ) |  |  | (1,618 | )
Taxes |  |  | (7,340 | ) |  |  | (11,622 | ) |  |  | 296 |  |  |  | 614 |
AOCI at year end |  | $ | 22,539 |  |  | $ | 18,965 |  |  | $ | (906 | ) |  | $ | (1,004 | )
Amounts Recognized in Accumulated Other Comprehensive Income, Net of Tax | Amounts recognized in accumulated other comprehensive income, net of tax, for the year ended December 31, are as follows:
|  | Pension Benefits |  |  | Post-retirement Benefits |
(000's omitted) |  | 2017 |  |  | 2016 |  |  | 2017 |  |  | 2016 |
Prior service cost/(credit) |  | $ | 424 |  |  | $ | (26 | ) |  | $ | 111 |  |  | $ | 110 |
Net (gain) loss |  |  | (851 | ) |  |  | (3,517 | ) |  |  | 148 |  |  |  | 111 |
Total |  | $ | (427 | ) |  | $ | (3,543 | ) |  | $ | 259 |  |  | $ | 221 |
Estimated Costs, Net of Tax, That Will Be Amortized from Accumulated Other Comprehensive (Income) Loss into Net Periodic (Income) Cost over Next Fiscal Year | The estimated costs, net of tax, that will be amortized from accumulated other comprehensive (income) loss into net periodic (income) cost over the next fiscal year are as follows:
(000's omitted) |  | Pension Benefits |  |  | Post-retirement Benefits |
Prior service credit |  | $ | (330 | ) |  | $ | (179 | )
Net loss |  |  | 1,054 |  |  |  | 18 |
Total |  | $ | 724 |  |  | $ | (161 | )
Weighted Average Assumptions Used To Determine Benefit Obligations | The weighted-average assumptions used to determine the benefit obligations as of December 31 are as follows:
|  | Pension Benefits |  |  | Post-retirement Benefits |
|  | 2017 |  |  | 2016 |  |  | 2017 |  |  | 2016 |
Discount rate |  |  | 4.00 | % |  |  | 4.50 | % |  |  | 4.00 | % |  |  | 4.40 | %
Expected return on plan assets |  |  | 7.00 | % |  |  | 7.00 | % |  |  | N/A |  |  |  | N/A |
Rate of compensation increase |  |  | 3.50 | % |  |  | 3.50 | % |  |  | N/A |  |  |  | N/A |
Net Periodic Benefit Cost | The net periodic benefit cost as of December 31 is as follows:
|  | Pension Benefits |  |  | Post-retirement Benefits |
(000's omitted) |  | 2017 |  |  | 2016 |  |  | 2015 |  |  | 2017 |  |  | 2016 |  |  | 2015 |
Service cost |  | $ | 4,181 |  |  | $ | 4,106 |  |  | $ | 3,324 |  |  | $ | 0 |  |  | $ | 0 |  |  | $ | 0 |
Interest cost |  |  | 5,717 |  |  |  | 5,624 |  |  |  | 5,506 |  |  |  | 76 |  |  |  | 82 |  |  |  | 87 |
Expected return on plan assets |  |  | (13,354 | ) |  |  | (11,842 | ) |  |  | (12,169 | ) |  |  | 0 |  |  |  | 0 |  |  |  | 0 |
Plan amendment |  |  | 0 |  |  |  | 20 |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |
Amortization of unrecognized net loss/(gain) |  |  | 767 |  |  |  | 1,508 |  |  |  | 1,466 |  |  |  | 8 |  |  |  | (5 | ) |  |  | (13 | )
Amortization of prior service cost |  |  | 55 |  |  |  | 43 |  |  |  | 8 |  |  |  | (179 | ) |  |  | (179 | ) |  |  | (179 | )
Net periodic (benefit) |  | $ | (2,634 | ) |  | $ | (541 | ) |  | $ | (1,865 | ) |  | $ | (95 | ) |  | $ | (102 | ) |  | $ | (105 | )
Weighted-Average Assumptions Used to Determine Benefit Obligations and Net Periodic Pension Cost | The weighted-average assumptions used to determine the net periodic pension cost for the years ended December 31 are as follows:
|  | Pension Benefits |  |  | Post-retirement Benefits |
|  | 2017 |  |  | 2016 |  |  | 2015 |  |  | 2017 |  |  | 2016 |  |  | 2015 |
Discount rate |  |  | 4.40 | % |  |  | 4.70 | % |  |  | 4.50 | % |  |  | 4.40 | % |  |  | 4.70 | % |  |  | 4.50 | %
Expected return on plan assets |  |  | 7.00 | % |  |  | 7.00 | % |  |  | 7.00 | % |  |  | N/A |  |  |  | N/A |  |  |  | N/A |
Rate of compensation increase |  |  | 3.50 | % |  |  | 3.50 | % |  |  | 3.50 | % |  |  | N/A |  |  |  | N/A |  |  |  | N/A |
Amount of Expected Benefit Payments | The amount of benefit payments that are expected to be paid over the next ten years are as follows:
(000's omitted) |  | Pension Benefits |  |  | Post-retirement Benefits |
2018 |  | $ | 8,702 |  |  | $ | 145 |
2019 |  |  | 9,163 |  |  |  | 142 |
2020 |  |  | 9,404 |  |  |  | 139 |
2021 |  |  | 9,943 |  |  |  | 136 |
2022 |  |  | 10,378 |  |  |  | 133 |
2023-2027 |  |  | 56,064 |  |  |  | 618 |
Fair Value of Defined Benefit Plan Assets by Asset Category | The fair values of the Company’s defined benefit pension plan assets at December 31, 2017 by asset category are as follows:
Asset category (000’s omitted) |  | Quoted Prices in Active Markets for Identical Assets Level 1 |  |  | Significant Observable Inputs Level 2 |  |  | Significant Unobservable Inputs Level 3 |  |  | Total |
Money Market Accounts |  | $ | 0 |  |  | $ | 10,381 |  |  | $ | 0 |  |  | $ | 10,381 |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. large-cap |  |  | 53,154 |  |  |  | 0 |  |  |  | 0 |  |  |  | 53,154 |
U.S mid/small cap |  |  | 26,309 |  |  |  | 0 |  |  |  | 0 |  |  |  | 26,309 |
CBU stock |  |  | 8,344 |  |  |  | 0 |  |  |  | 0 |  |  |  | 8,344 |
International |  |  | 47,723 |  |  |  | 0 |  |  |  | 0 |  |  |  | 47,723 |
|  |  | 135,530 |  |  |  | 0 |  |  |  | 0 |  |  |  | 135,530 |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Government securities |  |  | 13,929 |  |  |  | 9,686 |  |  |  | 0 |  |  |  | 23,615 |
Investment grade bonds |  |  | 19,278 |  |  |  | 0 |  |  |  | 0 |  |  |  | 19,278 |
High yield(a) |  |  | 16,297 |  |  |  | 0 |  |  |  | 0 |  |  |  | 16,297 |
|  |  | 49,504 |  |  |  | 9,686 |  |  |  | 0 |  |  |  | 59,190 |
Other investments (b) |  |  | 11,302 |  |  |  | 73 |  |  |  | 0 |  |  |  | 11,375 |
Total (c) |  | $ | 196,336 |  |  | $ | 20,140 |  |  | $ | 0 |  |  | $ | 216,476 |
The fair values of the Company’s defined benefit pension plan assets at December 31, 2016 by asset category are as follows:
Asset category (000’s omitted) |  | Quoted Prices in Active Markets for Identical Assets Level 1 |  |  | Significant Observable Inputs Level 2 |  |  | Significant Unobservable Inputs Level 3 |  |  | Total |
Money Market Accounts |  | $ | 103 |  |  | $ | 8,048 |  |  | $ | 0 |  |  | $ | 8,151 |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. large-cap |  |  | 43,235 |  |  |  | 0 |  |  |  | 0 |  |  |  | 43,235 |
U.S mid/small cap |  |  | 19,032 |  |  |  | 0 |  |  |  | 0 |  |  |  | 19,032 |
CBU stock |  |  | 7,417 |  |  |  | 0 |  |  |  | 0 |  |  |  | 7,417 |
International |  |  | 27,064 |  |  |  | 0 |  |  |  | 0 |  |  |  | 27,064 |
|  |  | 96,748 |  |  |  | 0 |  |  |  | 0 |  |  |  | 96,748 |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Government securities |  |  | 25,375 |  |  |  | 5,863 |  |  |  | 0 |  |  |  | 31,238 |
Investment grade bonds |  |  | 15,253 |  |  |  | 0 |  |  |  | 0 |  |  |  | 15,253 |
High yield(a) |  |  | 16,615 |  |  |  | 0 |  |  |  | 0 |  |  |  | 16,615 |
|  |  | 57,243 |  |  |  | 5,863 |  |  |  | 0 |  |  |  | 63,106 |
Other investments (b) |  |  | 12,023 |  |  |  | 58 |  |  |  | 0 |  |  |  | 12,081 |
Total (c) |  | $ | 166,117 |  |  | $ | 13,969 |  |  | $ | 0 |  |  | $ | 180,086 |
(a) | This category is exchange-traded funds representing a diversified index of high yield corporate bonds.
(b) | This category is comprised of exchange-traded funds and mutual funds holding non-traditional investment classes including private equity funds and alternative exchange funds.
(c) | Excludes dividends and interest receivable totaling $0.6 million and $0.3 million at December 31, 2017 and 2016, respectively.

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