SECURITIES (Securities Debt Maturities) (Details) - USD ($) $ in Thousands	Sep. 30, 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	5,668
Trading Securities, Amortized Cost, Maturing after five years through ten years	3,245
Trading Securities, Amortized Cost, Maturing after ten years through twenty years	276
Trading Securities, Amortized Cost, Maturing after twenty years	26,916
Trading Securities, Amortized Cost, Total with contractual maturity	36,105
Trading Securities, Amortized Cost, Equity securities	14
Trading Securities, Amortized Cost	36,119	$ 39,344
Trading Securities, Fair Value, Maturing in one year or less	0
Trading Securities, Fair Value, Maturing after one year through five years	5,969
Trading Securities, Fair Value, Maturing after five years through ten years	3,596
Trading Securities, Fair Value, Maturing after ten years through twenty years	310
Trading Securities, Fair Value, Maturing after twenty years	20,925
Trading Securities, Fair Value, Total with contractual maturity	30,800
Trading Securities, Fair Value, Equity securities	89
Trading Securities, Fair Value	30,889	34,134
Available-for-sale Securities, Amortized Cost, Maturing in one year or less	13,178
Available-for-sale Securities, Amortized Cost, Maturing after one year through five years	179,161
Available-for-sale Securities, Amortized Cost, Maturing after five years through ten years	203,970
Available-for-sale Securities, Amortized Cost, Maturing after ten years through twenty years	240,518
Available-for-sale Securities, Amortized Cost, Maturing after twenty years	356,998
Available-for-sale Securities, Amortized Cost, Total with contractual maturity	993,825
Available-for-sale Securities, Amortized Cost, Equity securities	88
Available-for-sale Securities, Amortized Cost	993,913	1,139,740
Available-for-sale Securities, Fair Value, Maturing in one year or less	13,175
Available-for-sale Securities, Fair Value, Maturing after one year through five years	180,625
Available-for-sale Securities, Fair Value, Maturing after five years through ten years	206,203
Available-for-sale Securities, Fair Value, Maturing after ten years through twenty years	244,927
Available-for-sale Securities, Fair Value, Maturing after twenty years	361,386
Available-for-sale Securities, Fair Value, Total with contractual maturity	1,006,316
Available-for-sale Securities, Fair Value, Equity securities	98
Available-for-sale Securities, Fair Value	1,006,414	1,138,573
Held-to-maturity Securities, Amortized Cost, Maturing in one year or less	2,561
Held-to-maturity Securities, Amortized Cost, Maturing after one year through five years	15,252
Held-to-maturity Securities, Amortized Cost, Maturing after five years through ten years	112,199
Held-to-maturity Securities, Amortized Cost, Maturing after ten years through twenty years	96,601
Held-to-maturity Securities, Amortized Cost, Maturing after twenty years	45,362
Held-to-maturity Securities, Amortized Cost	271,975	220,666
Held-to-maturity Securities, Fair Value, Maturing in one year or less	2,583
Held-to-maturity Securities, Fair Value, Maturing after one year through five years	15,500
Held-to-maturity Securities, Fair Value, Maturing after five years through ten years	116,736
Held-to-maturity Securities, Fair Value, Maturing after ten years through twenty years	102,641
Held-to-maturity Securities, Fair Value, Maturing after twenty years	45,843
Held-to-maturity Securities, Fair Value	$ 283,303	$ 226,627