ACQUISITIONS, Intangible Asset, Goodwill and Acquisition-related Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Summary of loans acquired [Abstract]
Merger and acquisition integration-related expenses	$ 71	$ 22,896	$ 63	$ 24,612
HR Consultants (SA), LLC [Member] | Core Deposits [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
HR Consultants (SA), LLC [Member] | Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Penna & Associates Agency, Inc. [Member] | Core Deposits [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Penna & Associates Agency, Inc. [Member] | Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Styles Bridges Associates [Member] | Core Deposits [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Styles Bridges Associates [Member] | Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Gordon B. Roberts Agency, Inc [Member] | Core Deposits [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Gordon B. Roberts Agency, Inc [Member] | Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Northeast Capital Management, Inc [Member] | Core Deposits [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Northeast Capital Management, Inc [Member] | Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Merchants Bancshares, Inc. [Member] | Core Deposits [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Merchants Bancshares, Inc. [Member] | Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Dryfoos Insurance Agency, Inc [Member] | Core Deposits [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Dryfoos Insurance Agency, Inc [Member] | Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Benefits Advisory Service, Inc [Member] | Core Deposits [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years
Benefits Advisory Service, Inc [Member] | Other Intangibles [Member]
Intangible Assets [Abstract]
Estimated useful life			8 years