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ACQUISITIONS (Details) shares in Thousands, $ in Thousands |  |  |  |  |  |  |  |  |  |  |  |  | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 21, 2019 USD ($) Branch County | Sep. 18, 2019 USD ($) | Jul. 12, 2019 USD ($) County Branch | Jan. 02, 2019 USD ($) | Apr. 02, 2018 USD ($) | Jan. 02, 2018 USD ($) | Dec. 04, 2017 USD ($) shares | Nov. 17, 2017 USD ($) | May 12, 2017 USD ($) Branch shares | Mar. 01, 2017 USD ($) | Feb. 03, 2017 USD ($) | Jan. 01, 2017 USD ($) | Dec. 31, 2019 USD ($) County | Dec. 31, 2018 USD ($) | Jun. 30, 2018 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2019 USD ($) County | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Jan. 02, 2017 USD ($)
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  | $ 500 | $ 95,034 |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 4,653 | $ 1,737 | $ 107,414 |
Purchase price of acquisition |  |  | 95,034 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other liabilities |  |  | 3,259 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill |  |  | 40,307 |  |  |  |  |  |  |  |  |  | $ 773,810 | $ 733,503 |  |  | 773,810 | 733,503 | 734,430 |
Investment securities |  |  | 39,770 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase in deposits |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 104,435 | (122,049) | $ (79,940) |
Vermont [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of counties where the bank has facilities | County |  |  |  |  |  |  |  |  |  |  |  |  | 12 |  |  |  | 12 |  |  |
Massachusetts [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of counties where the bank has facilities | County |  |  |  |  |  |  |  |  |  |  |  |  | 1 |  |  |  | 1 |  |  |
New York [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of counties where the bank has facilities | County |  |  |  |  |  |  |  |  |  |  |  |  | 40 |  |  |  | 40 |  |  |
Customer Lists [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  | $ 500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other Intangibles [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  |  | 1,650 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Steuben Trust Corporation [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash | $ 104,400 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Steuben Trust Corporation [Member] | Western New York State [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of branch locations | Branch | 14 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of new counties where the bank has extended footprints | Branch | 2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of counties where the bank has facilities | County | 4 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Kinderhook Bank Corp [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  |  | 93,384 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Purchase price of acquisition |  |  | $ 93,384 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of branch locations | Branch |  |  | 11 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other liabilities |  |  | $ 3,259 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill |  |  | 40,307 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investment securities |  |  | $ 39,770 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase (decrease) in other liabilities as a result of reclassification and adjustment |  |  |  |  |  |  |  |  |  |  |  |  | $ 40 |  |  |  |  |  |  |
Increase (decrease) in goodwill as a result of fair value adjustment |  |  |  |  |  |  |  |  |  |  |  |  | 200 |  |  |  |  |  |  |
Increase in deposits |  |  |  |  |  |  |  |  |  |  |  |  | 80 |  |  |  |  |  |  |
Decrease in loans |  |  |  |  |  |  |  |  |  |  |  |  | (50) |  |  |  |  |  |  |
Decrease in other assets |  |  |  |  |  |  |  |  |  |  |  |  | (40) |  |  |  |  |  |  |
Increased in accrued interest and fees receivable |  |  |  |  |  |  |  |  |  |  |  |  | $ 10 |  |  |  |  |  |  |
Kinderhook Bank Corp [Member] | Upstate New York [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of counties where the bank has facilities | County |  |  | 5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Assets acquired |  |  | $ 642,800 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue earned |  |  | 10,600 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Direct expenses |  |  | 4,700 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Kinderhook Bank Corp [Member] | Other Intangibles [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  |  | $ 0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Wealth Resources Network, Inc [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  |  |  | $ 1,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Wealth Resources Network, Inc [Member] | Customer Lists [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  |  |  | $ 1,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
HR Consultants (SA), LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  |  |  |  | $ 300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
HR Consultants (SA), LLC [Member] | Customer Lists [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  |  |  |  | $ 300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Penna & Associates Agency, Inc. [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  |  |  |  |  | $ 800 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  | 300 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Penna & Associates Agency, Inc. [Member] | Customer Lists [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  |  |  |  |  | 300 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Styles Bridges Associates [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  |  |  |  |  | 700 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Styles Bridges Associates [Member] | Customer Lists [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  |  |  |  |  | $ 700 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gordon B. Roberts Agency, Inc [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  |  |  |  |  |  | $ 1,350 |  |  |  |  |  |  |  |  |  |  |  |  |
Purchase price of acquisition |  |  |  |  |  |  | $ 3,700 |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance of common shares (in shares) | shares |  |  |  |  |  |  | 40 |  |  |  |  |  |  |  |  |  |  |  |  |
Assets acquired |  |  |  |  |  |  | $ 600 |  |  |  |  |  |  |  |  |  |  |  |  |
Other liabilities |  |  |  |  |  |  | 600 |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  | 2,100 |  |  |  |  |  |  |  |  |  |  |  |  |
Increase (decrease) in other liabilities as a result of reclassification and adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  | 20 | $ (90) |  |  |  |  |
Increase (decrease) in goodwill as a result of fair value adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 20 | $ (90) |  |  |  |  |
Gordon B. Roberts Agency, Inc [Member] | Other Intangibles [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  |  |  |  |  |  | $ 1,600 |  |  |  |  |  |  |  |  |  |  |  |  |
Northeast Capital Management, Inc [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  |  |  |  |  |  |  | $ 1,200 |  |  |  |  |  |  |  |  |  |  |  |
Northeast Capital Management, Inc [Member] | Customer Lists [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  |  |  |  |  |  |  | $ 1,200 |  |  |  |  |  |  |  |  |  |  |  |
Dryfoos [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  |  |  |  |  |  |  |  |  | $ 3,000 |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  |  |  |  | 1,700 |  |  |  |  |  |  |  |  |  |
Dryfoos [Member] | Other Intangibles [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  |  |  |  |  |  |  |  |  | $ 1,700 |  |  |  |  |  |  |  |  |  |
BAS [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  |  |  |  |  |  |  |  |  |  |  | $ 1,200 |  |  |  |  |  |  |  |
BAS [Member] | Other Intangibles [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,200
Merchants Bancshares, Inc. [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  |  |  |  |  |  |  |  | $ 82,898 |  |  |  |  |  |  |  |  |  |  |
Purchase price of acquisition |  |  |  |  |  |  |  |  | $ 345,152 |  |  |  |  |  |  |  |  |  |  |
Issuance of common shares (in shares) | shares |  |  |  |  |  |  |  |  | 4,680 |  |  |  |  |  |  |  |  |  |  |
Assets acquired |  |  |  |  |  |  |  |  | $ 2,000,000 |  |  |  |  |  |  |  |  |  |  |
Other liabilities |  |  |  |  |  |  |  |  | 11,750 |  |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  |  |  | 189,046 |  |  |  |  |  |  |  |  |  |  |
Investment securities |  |  |  |  |  |  |  |  | $ 370,648 |  |  |  |  |  |  |  |  |  |  |
Revenue earned |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 55,800 | 61,200 |  |
Direct expenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 29,400 | 30,800 |  |
Merchants Bancshares, Inc. [Member] | Vermont [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of branch locations | Branch |  |  |  |  |  |  |  |  | 31 |  |  |  |  |  |  |  |  |  |  |
Merchants Bancshares, Inc. [Member] | Massachusetts [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of branch locations | Branch |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |  |
Merchants Bancshares, Inc. [Member] | Other Intangibles [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  |  |  |  |  |  |  |  | $ 2,857 |  |  |  |  |  |  |  |  |  |  |
NRS [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash |  |  |  |  |  |  |  |  |  |  | $ 70,073 |  |  |  |  |  |  |  |  |
Purchase price of acquisition |  |  |  |  |  |  |  |  |  |  | 148,556 |  |  |  |  |  |  |  |  |
Tangible assets, net |  |  |  |  |  |  |  |  |  |  | $ 36,100 |  |  |  |  |  |  |  |  |
Factor of straight-line rate of depreciation used in declining balance depreciation method |  |  |  |  |  |  |  |  |  |  | 150.00% |  |  |  |  |  |  |  |  |
Period of amortization |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10 years |  |  |
Deferred tax liability |  |  |  |  |  |  |  |  |  |  | $ 23,000 |  |  |  |  |  |  |  |  |
Other liabilities |  |  |  |  |  |  |  |  |  |  | 26,828 |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  |  |  |  |  | 75,256 |  |  |  |  |  |  |  |  |
Investment securities |  |  |  |  |  |  |  |  |  |  | 20,294 |  |  |  |  |  |  |  |  |
Revenue earned |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 44,000 | 40,600 |  |
Direct expenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 23,900 | $ 24,600 |  |
Increase (decrease) in other liabilities as a result of reclassification and adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (1,200) |  |  |  |
Increase (decrease) in goodwill as a result of fair value adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (1,200) |  |  |  |
NRS [Member] | Other Intangibles [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangibles |  |  |  |  |  |  |  |  |  |  | $ 60,200 |  |  |  |  |  |  |  |  |

X
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X
- Definition Number of shares of equity interests issued or issuable to acquire entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b)(4) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 + Details
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