SECURITIES (Securities Debt Maturities) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
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	7,004
Trading Securities, Amortized Cost, Maturing after five years through ten years	3,401
Trading Securities, Amortized Cost, Maturing after ten years through twenty years	1,908
Trading Securities, Amortized Cost, Maturing after twenty years	26,828
Trading Securities, Amortized Cost, Total with contractual maturity	39,141
Trading Securities, Amortized Cost, Equity securities	14
Trading Securities, Amortized Cost	39,155	$ 39,344
Trading Securities, Fair Value, Maturing in one year or less	0
Trading Securities, Fair Value, Maturing after one year through five years	7,476
Trading Securities, Fair Value, Maturing after five years through ten years	3,786
Trading Securities, Fair Value, Maturing after ten years through twenty years	2,109
Trading Securities, Fair Value, Maturing after twenty years	20,542
Trading Securities, Fair Value, Total with contractual maturity	33,913
Trading Securities, Fair Value, Equity securities	81
Trading Securities, Fair Value	33,994	34,134
Available-for-sale Securities, Amortized Cost, Maturing in one year or less	12,792
Available-for-sale Securities, Amortized Cost, Maturing after one year through five years	241,156
Available-for-sale Securities, Amortized Cost, Maturing after five years through ten years	242,007
Available-for-sale Securities, Amortized Cost, Maturing after ten years through twenty years	327,867
Available-for-sale Securities, Amortized Cost, Maturing after twenty years	363,085
Available-for-sale Securities, Amortized Cost, Total with contractual maturity	1,186,907
Available-for-sale Securities, Amortized Cost, Equity securities	88
Available-for-sale Securities, Amortized Cost	1,186,995	1,139,740
Available-for-sale Securities, Fair Value, Maturing in one year or less	12,741
Available-for-sale Securities, Fair Value, Maturing after one year through five years	241,714
Available-for-sale Securities, Fair Value, Maturing after five years through ten years	243,516
Available-for-sale Securities, Fair Value, Maturing after ten years through twenty years	333,014
Available-for-sale Securities, Fair Value, Maturing after twenty years	368,196
Available-for-sale Securities, Fair Value, Total with contractual maturity	1,199,181
Available-for-sale Securities, Fair Value, Equity securities	98
Available-for-sale Securities, Fair Value	1,199,279	1,138,573
Held-to-maturity Securities, Amortized Cost, Maturing in one year or less	4,984
Held-to-maturity Securities, Amortized Cost, Maturing after one year through five years	14,600
Held-to-maturity Securities, Amortized Cost, Maturing after five years through ten years	98,569
Held-to-maturity Securities, Amortized Cost, Maturing after ten years through twenty years	106,288
Held-to-maturity Securities, Amortized Cost, Maturing after twenty years	21,879
Held-to-maturity Securities, Amortized Cost	246,320	220,666
Held-to-maturity Securities, Fair Value, Maturing in one year or less	5,014
Held-to-maturity Securities, Fair Value, Maturing after one year through five years	14,846
Held-to-maturity Securities, Fair Value, Maturing after five years through ten years	101,401
Held-to-maturity Securities, Fair Value, Maturing after ten years through twenty years	112,487
Held-to-maturity Securities, Fair Value, Maturing after twenty years	22,075
Held-to-maturity Securities, Fair Value	$ 255,823	$ 226,627