INVESTMENT SECURITIES, Investment Securities in a Continuous Unrealized Loss Position (Details) $ in Thousands	Mar. 31, 2016 USD ($) Position	Dec. 31, 2015 USD ($) Position
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	11	46
12 months or longer | Position	24	24
Total | Position	35	70
Available-for-Sale Portfolio in Unrealized Loss Positions, Fair Value [Abstract]
Less than 12 months	$ 6,624	$ 389,937
12 months or longer	33,668	33,551
Total	40,292	423,488
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	36	2,236
12 months or longer	527	1,183
Total	$ 563	$ 3,419
U.S. Treasury and Agency Obligations [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position		9
12 months or longer | Position		0
Total | Position		9
Available-for-Sale Portfolio in Unrealized Loss Positions, Fair Value [Abstract]
Less than 12 months		$ 353,844
12 months or longer		0
Total		353,844
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months		2,027
12 months or longer		0
Total		$ 2,027
Obligations of State and Political Subdivisions [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	1	18
12 months or longer | Position	2	2
Total | Position	3	20
Available-for-Sale Portfolio in Unrealized Loss Positions, Fair Value [Abstract]
Less than 12 months	$ 72	$ 8,804
12 months or longer	755	735
Total	827	9,539
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	0	34
12 months or longer	5	25
Total	$ 5	$ 59
Government Agency Mortgage-Backed Securities [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	9	17
12 months or longer | Position	19	19
Total | Position	28	36
Available-for-Sale Portfolio in Unrealized Loss Positions, Fair Value [Abstract]
Less than 12 months	$ 6,470	$ 24,178
12 months or longer	30,167	30,103
Total	36,637	54,281
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	17	161
12 months or longer	512	1,100
Total	$ 529	$ 1,261
Corporate Debt Securities [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	0	1
12 months or longer | Position	1	1
Total | Position	1	2
Available-for-Sale Portfolio in Unrealized Loss Positions, Fair Value [Abstract]
Less than 12 months	$ 0	$ 3,024
12 months or longer	2,743	2,710
Total	2,743	5,734
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	0	0
12 months or longer	10	58
Total	$ 10	$ 58
Government Agency Collateralized Mortgage Obligations [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	0	0
12 months or longer | Position	2	2
Total | Position	2	2
Available-for-Sale Portfolio in Unrealized Loss Positions, Fair Value [Abstract]
Less than 12 months	$ 0	$ 0
12 months or longer	3	3
Total	3	3
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	0	0
12 months or longer	0	0
Total	$ 0	$ 0
Marketable Equity Securities [Member]
Available-for-Sale Portfolio in Unrealized Loss Positions, Number of Positions [Abstract]
Less than 12 months | Position	1	1
12 months or longer | Position	0	0
Total | Position	1	1
Available-for-Sale Portfolio in Unrealized Loss Positions, Fair Value [Abstract]
Less than 12 months	$ 82	$ 87
12 months or longer	0	0
Total	82	87
Available-for-Sale Portfolio, Debt Maturities, Gross Unrealized Losses [Abstract]
Less than 12 months	19	14
12 months or longer	0	0
Total	$ 19	$ 14