INVESTMENTS IN DEBT AND EQUITY SECURITIES (Schedule of Continuous Unrealized Losses) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Available for sale:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 323,350	$ 566,896
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(2,187)	(19,441)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	211,199	10,253
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(5,138)	(315)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	534,549	577,149
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(7,325)	(19,756)
Held to maturity:
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	29,012	661,612
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(115)	(20,999)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	326,716	10,527
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(5,735)	(447)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	355,728	672,139
Held-to-maturity Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(5,850)	(21,446)
U.S. Government sponsored agencies [Member]
Held to maturity:
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value		15,966
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses		(153)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value		15,966
Held-to-maturity Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses		(153)
Residential mortgage-backed [Member]
Held to maturity:
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	28,371	644,700
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(112)	(20,759)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	325,820	10,527
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(5,670)	(447)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	354,191	655,227
Held-to-maturity Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(5,782)	(21,206)
State and political subdivisions [Member]
Held to maturity:
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	641	946
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(3)	(87)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	896	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(65)	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	1,537	946
Held-to-maturity Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(68)	(87)
U.S. Government sponsored agencies [Member]
Available for sale:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	79,207	16,005
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(427)	(664)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	14,600	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(130)	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	93,807	16,005
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(557)	(664)
Residential mortgage-backed [Member]
Available for sale:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	204,378	511,617
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(1,154)	(18,119)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	191,644	5,473
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(4,963)	(95)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	396,022	517,090
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(6,117)	(18,214)
State and political subdivisions [Member]
Available for sale:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	28,148	27,872
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(223)	(560)
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	28,148	27,872
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(223)	(560)
Corporate notes [Member]
Available for sale:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	9,650	9,959
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(350)	(41)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	4,955	4,780
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses	(45)	(220)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	14,605	14,739
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	(395)	(261)
Equity investments [Member]
Available for sale:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	1,967	1,443
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	(33)	(57)
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	1,967	1,443
Available-for-sale Securities, Continuous Unrealized Loss Position, Gross Unrealized Losses	$ (33)	$ (57)