SECURITIES (Securities Debt Maturities) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
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	25,097
Trading Securities, Fair Value, Maturing after twenty years	0
Trading Securities, Fair Value	25,097	24,980
Available-for-sale Securities, Amortized Cost, Maturing in one year or less	163,091
Available-for-sale Securities, Amortized Cost, Maturing after one year through five years	180,657
Available-for-sale Securities, Amortized Cost, Maturing after five years through ten years	717,085
Available-for-sale Securities, Amortized Cost, Maturing after ten years through twenty years	398,925
Available-for-sale Securities, Amortized Cost, Maturing after twenty years	1,789,821
Available-for-sale Securities, Amortized Cost	3,249,579	2,256,189
Available-for-sale Securities, Fair Value, Maturing in one year or less	163,421
Available-for-sale Securities, Fair Value, Maturing after one year through five years	189,261
Available-for-sale Securities, Fair Value, Maturing after five years through ten years	721,323
Available-for-sale Securities, Fair Value, Maturing after ten years through twenty years	414,207
Available-for-sale Securities, Fair Value, Maturing after twenty years	1,787,767
Available-for-sale Securities, Fair Value	3,275,979	2,322,593
Held-to-maturity Securities, Amortized Cost, Maturing in one year or less	5,085
Held-to-maturity Securities, Amortized Cost, Maturing after one year through five years	60,870
Held-to-maturity Securities, Amortized Cost, Maturing after five years through ten years	23,764
Held-to-maturity Securities, Amortized Cost, Maturing after ten years through twenty years	167,344
Held-to-maturity Securities, Amortized Cost, Maturing after twenty years	198,303
Held-to-maturity Securities, Amortized Cost	455,366	421,807
Held-to-maturity Securities, Fair Value, Maturing in one year or less	5,125
Held-to-maturity Securities, Fair Value, Maturing after one year through five years	63,365
Held-to-maturity Securities, Fair Value, Maturing after five years through ten years	25,531
Held-to-maturity Securities, Fair Value, Maturing after ten years through twenty years	173,728
Held-to-maturity Securities, Fair Value, Maturing after twenty years	212,228
Debt Securities, Held-to-maturity, Fair Value	$ 479,977	$ 448,681