SECURITIES (Securities Debt Maturities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Amortized Cost
Maturing in one year or less	$ 0
Maturing after one year through five years	0
Maturing after five years through ten years	0
Maturing after ten years through twenty years	27,203
Maturing after twenty years	0
Total with Maturity Date	27,203
Trading Securities, Cost	27,203	$ 27,203
Fair Value
Maturing in one year or less	0
Maturing after one year through five years	0
Maturing after five years through ten years	0
Maturing after ten years through twenty years	25,636
Maturing after twenty years	0
Total with Maturity Date	25,636
Amortized Cost
Maturing in one year or less	1,630
Maturing after one year through five years	48,703
Maturing after five years through ten years	358,305
Maturing after ten years through twenty years	243,275
Maturing after twenty years	878,033
Total with Maturity Date	1,529,946
Available-for-sale Securities, Amortized Cost	1,529,946	1,648,421
Fair Value
Maturing in one year or less	1,630
Maturing after one year through five years	49,614
Maturing after five years through ten years	368,950
Maturing after ten years through twenty years	247,506
Maturing after twenty years	883,857
Total with Maturity Date	1,551,557
Fair Value	1,551,557	1,636,223
Amortized Cost
Maturing in one year or less	810
Maturing after one year through five years	61,664
Maturing after five years through ten years	42,872
Maturing after ten years through twenty years	103,066
Maturing after twenty years	27,682
Debt Securities, Held-to-maturity	236,094	234,220
Fair Value
Maturing in one year or less	811
Maturing after one year through five years	62,582
Maturing after five years through ten years	44,372
Maturing after ten years through twenty years	102,540
Maturing after twenty years	27,500
Debt Securities, Held-to-maturity, Fair Value	$ 237,805	$ 232,537