SECURITIES (Securities Debt Maturities) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Trading Securities, Amortized Cost, Maturing in one year or less	$ 0
Trading Securities, Amortized Cost, Maturing after one year through five years	0
Trading Securities, Amortized Cost, Maturing after five years through ten years	0
Trading Securities, Amortized Cost, Maturing after ten years through twenty years	27,203
Trading Securities, Amortized Cost, Maturing after twenty years	0
Trading Securities, Amortized Cost	27,203	$ 27,203
Trading Securities, Fair Value, Maturing in one year or less	0
Trading Securities, Fair Value, Maturing after one year through five years	0
Trading Securities, Fair Value, Maturing after five years through ten years	0
Trading Securities, Fair Value, Maturing after ten years through twenty years	25,741
Trading Securities, Fair Value, Maturing after twenty years	0
Trading Securities, Fair Value	25,741	25,896
Available-for-sale Securities, Amortized Cost, Maturing in one year or less	2,554
Available-for-sale Securities, Amortized Cost, Maturing after one year through five years	57,247
Available-for-sale Securities, Amortized Cost, Maturing after five years through ten years	393,053
Available-for-sale Securities, Amortized Cost, Maturing after ten years through twenty years	178,802
Available-for-sale Securities, Amortized Cost, Maturing after twenty years	904,119
Available-for-sale Securities, Amortized Cost	1,535,775	1,648,421
Available-for-sale Securities, Fair Value, Maturing in one year or less	2,556
Available-for-sale Securities, Fair Value, Maturing after one year through five years	58,238
Available-for-sale Securities, Fair Value, Maturing after five years through ten years	404,449
Available-for-sale Securities, Fair Value, Maturing after ten years through twenty years	183,689
Available-for-sale Securities, Fair Value, Maturing after twenty years	912,077
Available-for-sale Securities, Fair Value	1,561,009	1,636,223
Held-to-maturity Securities, Amortized Cost, Maturing in one year or less	4,602
Held-to-maturity Securities, Amortized Cost, Maturing after one year through five years	63,805
Held-to-maturity Securities, Amortized Cost, Maturing after five years through ten years	43,943
Held-to-maturity Securities, Amortized Cost, Maturing after ten years through twenty years	58,805
Held-to-maturity Securities, Amortized Cost, Maturing after twenty years	32,067
Held-to-maturity Securities, Amortized Cost	203,222	234,220
Held-to-maturity Securities, Fair Value, Maturing in one year or less	4,604
Held-to-maturity Securities, Fair Value, Maturing after one year through five years	64,663
Held-to-maturity Securities, Fair Value, Maturing after five years through ten years	45,457
Held-to-maturity Securities, Fair Value, Maturing after ten years through twenty years	60,672
Held-to-maturity Securities, Fair Value, Maturing after twenty years	31,521
Debt Securities, Held-to-maturity, Fair Value	$ 206,917	$ 232,537