The amount of identifiable net tangible assets acquired at the acquisition date.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Amount of assets acquired at the acquisition date.

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Amount of deferred tax liability attributable to taxable temporary differences assumed at the acquisition date.

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The amount of identifiable intangible assets recognized as of the acquisition date.

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Amount of other liabilities due after one year or the normal operating cycle, if longer, assumed at the acquisition date.

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Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of addition (reduction) to the amount at which a liability could be incurred (settled) in a current transaction between willing parties.

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Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

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The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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ACQUISITIONS (Details) shares in Thousands, $ in Thousands									3 Months Ended			12 Months Ended
ACQUISITIONS (Details) shares in Thousands, $ in Thousands	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, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 02, 2017 USD ($)
Acquisitions [Abstract]
Cash												$ 1,737	$ 107,414	$ 575
Goodwill									$ 733,503			733,503	734,430	$ 465,142
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
Revenue earned												61,200	42,600
Expenses incurred												$ 30,800	19,900
Merchants Bancshares, Inc. [Member] \| Vermont [Member]
Acquisitions [Abstract]
Number of branch locations added upon merger \| Branch					31
Merchants Bancshares, Inc. [Member] \| Massachusetts [Member]
Acquisitions [Abstract]
Number of branch locations added upon merger \| Branch					1
Merchants Bancshares, Inc. [Member] \| Other Intangibles [Member]
Acquisitions [Abstract]
Intangibles					$ 2,857
Northeast Retirement Services, Inc. [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
Revenue earned												$ 40,600	31,500
Expenses incurred												$ 24,600	$ 21,500
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)
Northeast Retirement Services, Inc. [Member] \| Other Intangibles [Member]
Acquisitions [Abstract]
Intangibles							$ 60,200