SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE - Contractual Maturity of Secured Borrowings and Class of Collateral Pledged (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Available-for-sale Securities Pledged as Collateral	$ 192,770	$ 241,964
Held-to-maturity Securities Pledged as Collateral	56,812	70,154
Overnight and Continuous
Available-for-sale Securities Pledged as Collateral	192,770	241,964
Held-to-maturity Securities Pledged as Collateral	56,812	70,154
U.S. Treasury Obligations
Available-for-sale Securities Pledged as Collateral	10,064	24,207
U.S. Treasury Obligations | Overnight and Continuous
Available-for-sale Securities Pledged as Collateral	10,064	24,207
U.S. Agency Obligations
Held-to-maturity Securities Pledged as Collateral	14,714	16,646
U.S. Agency Obligations | Overnight and Continuous
Held-to-maturity Securities Pledged as Collateral	14,714	16,646
U.S. GSEs
Available-for-sale Securities Pledged as Collateral	47,745	51,847
U.S. GSEs | Overnight and Continuous
Available-for-sale Securities Pledged as Collateral	47,745	51,847
FHLB Obligations
Available-for-sale Securities Pledged as Collateral	58,519	59,505
FHLB Obligations | Overnight and Continuous
Available-for-sale Securities Pledged as Collateral	58,519	59,505
Agency MBSs
Available-for-sale Securities Pledged as Collateral	33,553	44,736
Agency MBSs | Overnight and Continuous
Available-for-sale Securities Pledged as Collateral	33,553	44,736
Agency CMBSs
Available-for-sale Securities Pledged as Collateral	18,961	21,662
Held-to-maturity Securities Pledged as Collateral	42,098
Agency CMBSs | Overnight and Continuous
Available-for-sale Securities Pledged as Collateral	18,961	21,662
Held-to-maturity Securities Pledged as Collateral	42,098
Agency CMOs
Available-for-sale Securities Pledged as Collateral	23,928	40,007
Held-to-maturity Securities Pledged as Collateral		53,508
Agency CMOs | Overnight and Continuous
Available-for-sale Securities Pledged as Collateral	$ 23,928	40,007
Held-to-maturity Securities Pledged as Collateral		$ 53,508