INVESTMENTS IN DEBT AND EQUITY SECURITIES (Schedule of Continuous Unrealized Losses) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 404,995	$ 566,896
Available-for-sale Securities, Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses	(11,670)	(19,441)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	49,861	10,253
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer Aggregate Losses	(1,967)	(315)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	454,856	577,149
Available-for-sale Securities, Continuous Unrealized Loss Position Aggregate Losses	(13,637)	(19,756)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	566,928	661,612
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(11,207)	(20,999)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	84,920	10,527
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(3,111)	(447)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	651,848	672,139
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	(14,318)	(21,446)
U.S. Government sponsored agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	0	16,005
Available-for-sale Securities, Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses	0	(664)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	14,670	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer Aggregate Losses	(47)	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	14,670	16,005
Available-for-sale Securities, Continuous Unrealized Loss Position Aggregate Losses	(47)	(664)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	14,238	15,966
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(135)	(153)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	14,238	15,966
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	(135)	(153)
Residential mortgage-backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	355,453	511,617
Available-for-sale Securities, Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses	(11,046)	(18,119)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	25,617	5,473
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer Aggregate Losses	(1,494)	(95)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	381,070	517,090
Available-for-sale Securities, Continuous Unrealized Loss Position Aggregate Losses	(12,540)	(18,214)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	551,649	644,700
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(10,990)	(20,759)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	84,920	10,527
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(3,111)	(447)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	636,569	655,227
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	(14,101)	(21,206)
State and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	28,025	27,872
Available-for-sale Securities, Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses	(392)	(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 Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	28,025	27,872
Available-for-sale Securities, Continuous Unrealized Loss Position Aggregate Losses	(392)	(560)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	1,041	946
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(82)	(87)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	1,041	946
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	(82)	(87)
Corporate notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	19,826	9,959
Available-for-sale Securities, Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses	(173)	(41)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	9,574	4,780
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer Aggregate Losses	(426)	(220)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	29,400	14,739
Available-for-sale Securities, Continuous Unrealized Loss Position Aggregate Losses	(599)	(261)
Equity investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	1,691	1,443
Available-for-sale Securities, Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses	(59)	(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 Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,691	1,443
Available-for-sale Securities, Continuous Unrealized Loss Position Aggregate Losses	$ (59)	$ (57)