INVESTMENT SECURITIES (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	$ 637,894,000	$ 553,495,000
Gross Unrealized Gains	66,063,000	64,340,000
Gross Unrealized Losses	0	0
Estimated Fair Value	703,957,000	617,835,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	1,989,938,000	1,453,461,000
Gross Unrealized Gains	144,037,000	110,211,000
Gross Unrealized Losses	12,581,000	24,699,000
Total available-for-sale investment securities	2,121,394,000	1,538,973,000
Other Securities [Abstract]
Amortized Cost	59,239,000	58,902,000
Estimated Fair Value	59,239,000	58,902,000
Available-for-Sale Securities, in Unrealized Loss Positions, Number of Positions [Abstract]
Available-for-sale securities in unrealized loss positions for less than 12 months, number of positions	32	23
Available-for-sale securities in unrealized loss positions for more than 12 months, number of positions	6	12
Total available-for-sale securities in unrealized loss positions, number of positions	38	35
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	29,188,000	9,397,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	50,799,000	49,069,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value	79,987,000	58,466,000
Available-for-Sale Securities, Debt maturities, Gross unrealized losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses	158,000	190,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	12,423,000	24,509,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	12,581,000	24,699,000
Held-to-Maturity, Amortized Cost [Abstract]
Held -to-maturity, Amortized Cost, Due in one year or less	18,502,000
Held -to-maturity, Amortized Cost, Due in one to five years	269,860,000
Held -to-maturity, Amortized Cost, Due in five through ten years	274,760,000
Held -to-maturity, Amortized Cost, Due after ten years	54,194,000
Held-to-maturity Securities, Amortized Cost, Subtotal	617,316,000
Held-to-maturity Collateralized Mortgage Obligations, Amortized Cost, without single maturity date	20,578,000
Held-to-maturity Mortgage Backed Securities, Amortized Cost, without single maturity date	0
Held-to-maturity, Amortized Cost	637,894,000
Held-to-Maturity, Fair value [Abstract]
Held-to-maturity, Fair value, Due in one year or less	18,788,000
Held-to-maturity, Fair value, Due after one through five years	297,891,000
Held-to-maturity, Fair value, Due in five through ten years	304,847,000
Held-to-maturity, Fair value, Due after ten years	60,774,000
Held-to-maturity Securities, Fair Value, Subtotal	682,300,000
Held-to-maturity Collateralized Mortgage Obligations, Fair Value, without single maturity date	21,657,000
Held-to-maturity Mortgage Backed Securities, Amortized Cost, without single maturity date	0
Held-to-maturity, Fair value	703,957,000
Available-for-Sale Securities, Amortized Cost [Abstract]
Available-for-sale securities, Amortized Cost, Due in one year or less	40,414,000
Available-for-sale securities, Amortized Cost, Due after one through five years	256,477,000
Available-for-sale securities, Amortized Cost, Due in five through ten years	945,139,000
Available-for-sale securities, Amortized Cost, Due after ten years	462,185,000
Available-for-sale Securities, Amortized Cost, Subtotal	1,704,215,000
Available-for-sale government agency collateralized mortgage obligations, amortized cost, without a single maturity date	253,013,000
Available-for-sale government agency mortgage-backed securities, amortized cost, without a single maturity date	32,359,000
Available-for-sale securities, Amortized Cost	1,989,587,000
Available-for-Sale Securities, Fair value [Abstract]
Available-for-sale securities, Fair value, Due in one year or less	41,087,000
Available-for-sale securities, Fair value, Due in one to five years	279,179,000
Available-for-sale securities, Fair value, Due in five through ten years	1,009,240,000
Available-for-sale securities, Fair value, Due after ten years	487,600,000
Available-for-sale Securities, Fair Value, Subtotal	1,817,106,000
Available-for-sale government agency collateralized mortgage obligations, fair value, without single maturity date	269,951,000
Available-for-sale government agency mortgage-backed securities, fair value, without single maturity date	33,935,000
Available-for-sale securities, Fair value	2,120,992,000
Pooled trust preferred, class A-1 securities, par value	63,300,000
Pooled trust preferred, class A-1 securities, unrealized losses	12,400,000
Percentage minimum for underlying collateral to be in deferral or default concurrently before non-receipt of contractual cash flows (in hundredths)	39.00%
Percentage maximum for underlying collateral to be in deferral or default concurrently before non-receipt of contractual cash flows (in hundredths)	43.00%
Cash flow information on investment securities [Abstract]
Gross gains on sales of investment securities	350,000	349,000	0
Gross losses on sales of investment securities	59,000	319,000	0
Proceeds from the maturities of mortgage-backed securities and CMO's	109,843,000	97,224,000	93,171,000
Purchases of mortgage-backed securities and CMO's	26,292,000	253,378,000	9,132,000
Investment securities pledged to collateralize certain deposits and borrowings	1,176,000,000	1,015,000,000
US Treasury and Agency Securities [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	548,634,000	448,260,000
Gross Unrealized Gains	59,081,000	56,800,000
Gross Unrealized Losses	0	0
Estimated Fair Value	607,715,000	505,060,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	988,217,000	463,922,000
Gross Unrealized Gains	91,040,000	56,626,000
Gross Unrealized Losses	0	0
Total available-for-sale investment securities	1,079,257,000	520,548,000
Obligations of State and Political Subdivisions [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	65,742,000	69,623,000
Gross Unrealized Gains	5,850,000	5,088,000
Gross Unrealized Losses	0	0
Estimated Fair Value	71,592,000	74,711,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	629,883,000	543,527,000
Gross Unrealized Gains	33,070,000	29,721,000
Gross Unrealized Losses	61,000	236,000
Total available-for-sale investment securities	662,892,000	573,012,000
Available-for-Sale Securities, in Unrealized Loss Positions, Number of Positions [Abstract]
Available-for-sale securities in unrealized loss positions for less than 12 months, number of positions	19	2
Available-for-sale securities in unrealized loss positions for more than 12 months, number of positions	0	6
Total available-for-sale securities in unrealized loss positions, number of positions	19	8
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	11,503,000	211,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	0	6,038,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value	11,503,000	6,249,000
Available-for-Sale Securities, Debt maturities, Gross unrealized losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses	61,000	0
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	0	236,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	61,000	236,000
Government Agency Mortgage-Backed Securities [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	20,578,000	35,576,000
Gross Unrealized Gains	1,079,000	2,452,000
Gross Unrealized Losses	0	0
Estimated Fair Value	21,657,000	38,028,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	253,013,000	310,541,000
Gross Unrealized Gains	16,989,000	20,840,000
Gross Unrealized Losses	51,000	2,000
Total available-for-sale investment securities	269,951,000	331,379,000
Available-for-Sale Securities, in Unrealized Loss Positions, Number of Positions [Abstract]
Available-for-sale securities in unrealized loss positions for less than 12 months, number of positions	8	3
Available-for-sale securities in unrealized loss positions for more than 12 months, number of positions	0	0
Total available-for-sale securities in unrealized loss positions, number of positions	8	3
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	14,354,000	2,415,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value	14,354,000	2,415,000
Available-for-Sale Securities, Debt maturities, Gross unrealized losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses	51,000	2,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	0	0
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	51,000	2,000
Pooled Trust Preferred Securities [Member]
Available-for-Sale Portfolio [Abstract]
Amortized Cost	61,979,000	68,115,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	12,379,000	24,269,000
Total available-for-sale investment securities	49,600,000	43,846,000
Available-for-Sale Securities, in Unrealized Loss Positions, Number of Positions [Abstract]
Available-for-sale securities in unrealized loss positions for less than 12 months, number of positions	0	0
Available-for-sale securities in unrealized loss positions for more than 12 months, number of positions	3	3
Total available-for-sale securities in unrealized loss positions, number of positions	3	3
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	0	0
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	49,600,000	43,019,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value	49,600,000	43,019,000
Available-for-Sale Securities, Debt maturities, Gross unrealized losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses	0	0
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	12,379,000	24,269,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	12,379,000	24,269,000
Corporate Debt Securities [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	2,924,000	0
Gross Unrealized Gains	53,000	0
Gross Unrealized Losses	0	0
Estimated Fair Value	2,977,000	0
Available-for-Sale Portfolio [Abstract]
Amortized Cost	24,136,000	21,495,000
Gross Unrealized Gains	1,265,000	1,360,000
Gross Unrealized Losses	44,000	0
Total available-for-sale investment securities	25,357,000	22,855,000
Available-for-Sale Securities, in Unrealized Loss Positions, Number of Positions [Abstract]
Available-for-sale securities in unrealized loss positions for less than 12 months, number of positions	1
Available-for-sale securities in unrealized loss positions for more than 12 months, number of positions	0
Total available-for-sale securities in unrealized loss positions, number of positions	1
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	2,905,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value	2,905,000
Available-for-Sale Securities, Debt maturities, Gross unrealized losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses	44,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	0
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	44,000
Government Agency Collateralized Mortgage Obligations [Member]
Available-for-Sale Portfolio [Abstract]
Amortized Cost	32,359,000	45,481,000
Gross Unrealized Gains	1,579,000	1,572,000
Gross Unrealized Losses	3,000	110,000
Total available-for-sale investment securities	33,935,000	46,943,000
Available-for-Sale Securities, in Unrealized Loss Positions, Number of Positions [Abstract]
Available-for-sale securities in unrealized loss positions for less than 12 months, number of positions	4	17
Available-for-sale securities in unrealized loss positions for more than 12 months, number of positions	2	0
Total available-for-sale securities in unrealized loss positions, number of positions	6	17
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	426,000	6,648,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	1,041,000	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value	1,467,000	6,648,000
Available-for-Sale Securities, Debt maturities, Gross unrealized losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses	2,000	110,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	1,000	0
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	3,000	110,000
Marketable Equity Security [Member]
Available-for-Sale Portfolio [Abstract]
Amortized Cost	351,000	380,000
Gross Unrealized Gains	94,000	92,000
Gross Unrealized Losses	43,000	82,000
Total available-for-sale investment securities	402,000	390,000
Available-for-Sale Securities, in Unrealized Loss Positions, Number of Positions [Abstract]
Available-for-sale securities in unrealized loss positions for less than 12 months, number of positions	0	1
Available-for-sale securities in unrealized loss positions for more than 12 months, number of positions	1	3
Total available-for-sale securities in unrealized loss positions, number of positions	1	4
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	0	123,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	158,000	12,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value	158,000	135,000
Available-for-Sale Securities, Debt maturities, Gross unrealized losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses	0	78,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	43,000	4,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	43,000	82,000
Federal Reserve Bank Stock [Member]
Other Securities [Abstract]
Amortized Cost	16,050,000	15,451,000
Estimated Fair Value	16,050,000	15,451,000
Federal Home Loan Bank Stock [Member]
Other Securities [Abstract]
Amortized Cost	38,111,000	38,343,000
Estimated Fair Value	38,111,000	38,343,000
Other Equity Securities [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	16,000	36,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	16,000	36,000
Other Securities [Abstract]
Amortized Cost	5,078,000	5,108,000
Estimated Fair Value	$ 5,078,000	$ 5,108,000