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ACQUISITIONS (Details) $ in Thousands |  |  |  |  | 3 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Jan. 22, 2019 USD ($) County Branch | Jan. 02, 2019 USD ($) | Apr. 02, 2018 USD ($) | Jan. 02, 2018 USD ($) | Mar. 31, 2019 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2018 USD ($)
Acquisitions [Abstract] |  |  |  |  |  |  |
Cash |  |  |  |  | $ 1,200 | $ 1,464 |
Goodwill |  |  |  |  | $ 733,503 | $ 733,625 | $ 733,503
Kinderhook Bank Corp [Member] |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |
Cash | $ 93,400 |  |  |  |  |  |
Number of branch locations added upon merger | Branch | 11 |  |  |  |  |  |
Kinderhook Bank Corp [Member] | Upstate New York [Member] |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |
Number of counties where the bank has facilities | County | 5 |  |  |  |  |  |
Wealth Resources Network, Inc [Member] |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |
Cash |  | $ 1,200 |  |  |  |  |
Goodwill |  | 0 |  |  |  |  |
Wealth Resources Network, Inc [Member] | Customer Lists [Member] |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |
Intangibles |  | $ 1,200 |  |  |  |  |
HR Consultants (SA), LLC [Member] |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |
Cash |  |  | $ 300 |  |  |  |
HR Consultants (SA), LLC [Member] | Customer Lists [Member] |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |
Intangibles |  |  | $ 300 |  |  |  |
Penna & Associates Agency, Inc. [Member] |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |
Cash |  |  |  | $ 800 |  |  |
Goodwill |  |  |  | 300 |  |  |
Penna & Associates Agency, Inc. [Member] | Customer Lists [Member] |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |
Intangibles |  |  |  | 300 |  |  |
Styles Bridges Associates [Member] |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |
Cash |  |  |  | 700 |  |  |
Styles Bridges Associates [Member] | Customer Lists [Member] |  |  |  |  |  |  |
Acquisitions [Abstract] |  |  |  |  |  |  |
Intangibles |  |  |  | $ 700 |  |  |

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