ACQUISITIONS, Summary of Loans Acquired (Details) - Oneida Financial Corp [Member] $ in Thousands	Dec. 04, 2015 USD ($)
Summary of loans acquired [Abstract]
Contractually required principal and interest at acquisition	$ 490,075
Contractual cash flows not expected to be collected	(6,810)
Expected cash flows at acquisition	483,265
Interest component of expected cash flows	(83,843)
Fair value of acquired loans	399,422
Acquired Impaired Loans [Member]
Summary of loans acquired [Abstract]
Contractually required principal and interest at acquisition	5,138
Contractual cash flows not expected to be collected	(1,977)
Expected cash flows at acquisition	3,161
Interest component of expected cash flows	(341)
Fair value of acquired loans	2,820
Acquired Non Impaired Loans [Member]
Summary of loans acquired [Abstract]
Contractually required principal and interest at acquisition	484,937
Contractual cash flows not expected to be collected	(4,833)
Expected cash flows at acquisition	480,104
Interest component of expected cash flows	(83,502)
Fair value of acquired loans	$ 396,602