FAIR VALUE (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets measured at fair value on recurring basis
Available for sale securities	$ 726,056	$ 759,916
U.S. GSE securities
Assets measured at fair value on recurring basis
Available for sale securities	56,038	56,814
State and municipal obligations
Assets measured at fair value on recurring basis
Available for sale securities	84,846	87,022
U.S. GSE residential mortgage-backed securities
Assets measured at fair value on recurring basis
Available for sale securities	175,567	186,901
U.S. GSE residential collateralized mortgage obligations
Assets measured at fair value on recurring basis
Available for sale securities	290,674	307,390
U.S. GSE commercial mortgage-backed securities
Assets measured at fair value on recurring basis
Available for sale securities	5,856	5,979
U.S. GSE commercial collateralized mortgage obligations
Assets measured at fair value on recurring basis
Available for sale securities	46,492	48,716
Other asset backed securities
Assets measured at fair value on recurring basis
Available for sale securities	23,401	23,401
Corporate bonds
Assets measured at fair value on recurring basis
Available for sale securities	43,182	43,693
Carrying Value
Assets measured at fair value on recurring basis
Available for sale securities	726,056	759,916
Financial Assets: Derivatives	7,374	4,546
Financial Liabilities:
Financial liabilities: Derivatives	1,759	1,823
Fair Value
Assets measured at fair value on recurring basis
Available for sale securities	726,056	759,916
Financial Assets: Derivatives	7,374	4,546
Financial Liabilities:
Financial liabilities: Derivatives	1,759	1,823
Quoted Prices In Active Markets for Identical Assets (Level 1) | Fair Value
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Financial Assets: Derivatives	0	0
Financial Liabilities:
Financial liabilities: Derivatives	0	0
Significant Other Observable Inputs (Level 2) | Fair Value
Assets measured at fair value on recurring basis
Available for sale securities	726,056	759,916
Financial Assets: Derivatives	7,374	4,546
Financial Liabilities:
Financial liabilities: Derivatives	1,759	1,823
Significant Unobservable Inputs (Level 3) | Fair Value
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Financial Assets: Derivatives	0	0
Financial Liabilities:
Financial liabilities: Derivatives	0	0
Recurring basis | Carrying Value
Assets measured at fair value on recurring basis
Available for sale securities	726,056	759,916
Recurring basis | Carrying Value | U.S. GSE securities
Assets measured at fair value on recurring basis
Available for sale securities	56,038	56,814
Recurring basis | Carrying Value | State and municipal obligations
Assets measured at fair value on recurring basis
Available for sale securities	84,846	87,022
Recurring basis | Carrying Value | U.S. GSE residential mortgage-backed securities
Assets measured at fair value on recurring basis
Available for sale securities	175,567	186,901
Recurring basis | Carrying Value | U.S. GSE residential collateralized mortgage obligations
Assets measured at fair value on recurring basis
Available for sale securities	290,674	307,390
Recurring basis | Carrying Value | U.S. GSE commercial mortgage-backed securities
Assets measured at fair value on recurring basis
Available for sale securities	5,856	5,979
Recurring basis | Carrying Value | U.S. GSE commercial collateralized mortgage obligations
Assets measured at fair value on recurring basis
Available for sale securities	46,492	48,716
Recurring basis | Carrying Value | Other asset backed securities
Assets measured at fair value on recurring basis
Available for sale securities	23,401	23,401
Recurring basis | Carrying Value | Corporate bonds
Assets measured at fair value on recurring basis
Available for sale securities	43,182	43,693
Recurring basis | Carrying Value | Derivatives
Assets measured at fair value on recurring basis
Financial Assets: Derivatives	7,374	4,546
Financial Liabilities:
Financial liabilities: Derivatives	1,759	1,823
Recurring basis | Quoted Prices In Active Markets for Identical Assets (Level 1) | Fair Value
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Quoted Prices In Active Markets for Identical Assets (Level 1) | Fair Value | U.S. GSE securities
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Quoted Prices In Active Markets for Identical Assets (Level 1) | Fair Value | State and municipal obligations
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Quoted Prices In Active Markets for Identical Assets (Level 1) | Fair Value | U.S. GSE residential mortgage-backed securities
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Quoted Prices In Active Markets for Identical Assets (Level 1) | Fair Value | U.S. GSE residential collateralized mortgage obligations
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Quoted Prices In Active Markets for Identical Assets (Level 1) | Fair Value | U.S. GSE commercial mortgage-backed securities
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Quoted Prices In Active Markets for Identical Assets (Level 1) | Fair Value | U.S. GSE commercial collateralized mortgage obligations
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Quoted Prices In Active Markets for Identical Assets (Level 1) | Fair Value | Other asset backed securities
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Quoted Prices In Active Markets for Identical Assets (Level 1) | Fair Value | Corporate bonds
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Quoted Prices In Active Markets for Identical Assets (Level 1) | Fair Value | Derivatives
Assets measured at fair value on recurring basis
Financial Assets: Derivatives	0	0
Financial Liabilities:
Financial liabilities: Derivatives	0	0
Recurring basis | Significant Other Observable Inputs (Level 2) | Fair Value
Assets measured at fair value on recurring basis
Available for sale securities	726,056	759,916
Recurring basis | Significant Other Observable Inputs (Level 2) | Fair Value | U.S. GSE securities
Assets measured at fair value on recurring basis
Available for sale securities	56,038	56,814
Recurring basis | Significant Other Observable Inputs (Level 2) | Fair Value | State and municipal obligations
Assets measured at fair value on recurring basis
Available for sale securities	84,846	87,022
Recurring basis | Significant Other Observable Inputs (Level 2) | Fair Value | U.S. GSE residential mortgage-backed securities
Assets measured at fair value on recurring basis
Available for sale securities	175,567	186,901
Recurring basis | Significant Other Observable Inputs (Level 2) | Fair Value | U.S. GSE residential collateralized mortgage obligations
Assets measured at fair value on recurring basis
Available for sale securities	290,674	307,390
Recurring basis | Significant Other Observable Inputs (Level 2) | Fair Value | U.S. GSE commercial mortgage-backed securities
Assets measured at fair value on recurring basis
Available for sale securities	5,856	5,979
Recurring basis | Significant Other Observable Inputs (Level 2) | Fair Value | U.S. GSE commercial collateralized mortgage obligations
Assets measured at fair value on recurring basis
Available for sale securities	46,492	48,716
Recurring basis | Significant Other Observable Inputs (Level 2) | Fair Value | Other asset backed securities
Assets measured at fair value on recurring basis
Available for sale securities	23,401	23,401
Recurring basis | Significant Other Observable Inputs (Level 2) | Fair Value | Corporate bonds
Assets measured at fair value on recurring basis
Available for sale securities	43,182	43,693
Recurring basis | Significant Other Observable Inputs (Level 2) | Fair Value | Derivatives
Assets measured at fair value on recurring basis
Financial Assets: Derivatives	7,374	4,546
Financial Liabilities:
Financial liabilities: Derivatives	1,759	1,823
Recurring basis | Significant Unobservable Inputs (Level 3) | Fair Value
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Fair Value | U.S. GSE securities
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Fair Value | State and municipal obligations
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Fair Value | U.S. GSE residential mortgage-backed securities
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Fair Value | U.S. GSE residential collateralized mortgage obligations
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Fair Value | U.S. GSE commercial mortgage-backed securities
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Fair Value | U.S. GSE commercial collateralized mortgage obligations
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Fair Value | Other asset backed securities
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Fair Value | Corporate bonds
Assets measured at fair value on recurring basis
Available for sale securities	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Fair Value | Derivatives
Assets measured at fair value on recurring basis
Financial Assets: Derivatives	0	0
Financial Liabilities:
Financial liabilities: Derivatives	$ 0	$ 0