INVESTMENTS IN DEBT AND EQUITY SECURITIES (Schedule of Continuous Unrealized Losses) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Held to maturity:
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 102,643	$ 29,012
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(413)	(115)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	120,804	326,716
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(1,659)	(5,735)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	223,447	355,728
Held-to-maturity Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(2,072)	(5,850)
Available for sale:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	203,215	323,350
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(1,883)	(2,187)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	137,092	211,199
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(2,234)	(5,138)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	340,307	534,549
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(4,117)	(7,325)
U.S. Government sponsored agencies [Member]
Available for sale:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	86,684	79,207
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(592)	(427)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	14,600	14,600
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(135)	(130)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	101,284	93,807
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(727)	(557)
Residential mortgage-backed [Member]
Available for sale:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	66,185	204,378
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(252)	(1,154)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	117,535	191,644
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(2,056)	(4,963)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	183,720	396,022
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(2,308)	(6,117)
State and political subdivisions [Member]
Available for sale:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	28,087	28,148
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(268)	(223)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	28,087	28,148
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(268)	(223)
Corporate notes [Member]
Available for sale:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	20,274	9,650
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(756)	(350)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	4,957	4,955
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(43)	(45)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	25,231	14,605
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(799)	(395)
Equity investments [Member]
Available for sale:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	1,985	1,967
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(15)	(33)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,985	1,967
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(15)	(33)
Residential mortgage-backed [Member]
Held to maturity:
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	100,000	28,371
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(386)	(112)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	119,905	325,820
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(1,598)	(5,670)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	219,905	354,191
Held-to-maturity Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(1,984)	(5,782)
State and political subdivisions [Member]
Held to maturity:
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	2,643	641
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(27)	(3)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	899	896
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(61)	(65)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	3,542	1,537
Held-to-maturity Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	$ (88)	$ (68)