ACQUISITIONS (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Island Bancorp, Inc. [Member]
Business Acquisition [Line Items]
Net interest income after provision for loan losses	$ 258,017	$ 227,429
Net income	$ 90,025	78,150
New England Bancorp, Inc. [Member]
Business Acquisition [Line Items]
Net interest income after provision for loan losses		228,927	$ 221,252
Net income		$ 80,411	$ 65,623