SECURITIES AVAILABLE FOR SALE - Schedule of Maturity of Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Available for sale, Amortized Cost
Within 1 year	$ 6,997
Over 1 year to 5 years	11,627
Over 5 years to 10 years	46,942
Over 10 years	110,450
Total bonds and obligations	176,016
Mortgage-backed securities	543,967
Amortized Cost	719,983	$ 532,125
Available for sale, Fair Value
Within 1 year	7,002
Over 1 year to 5 years	11,621
Over 5 years to 10 years	47,776
Over 10 years	111,569
Total bonds and obligations	177,968
Mortgage-backed securities	539,274
Available-for-sale securities, fair value	$ 717,242	$ 528,856