INVESTMENT SECURITIES (Details) (USD $)	3 Months Ended
	Mar. 31, 2013 Position	Dec. 31, 2012 Position
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	$ 631,984,000	$ 637,894,000
Gross Unrealized Gains	61,365,000	66,063,000
Gross Unrealized Losses	0	0
Estimated Fair Value	693,349,000	703,957,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	1,708,841,000	1,989,938,000
Gross Unrealized Gains	76,754,000	144,037,000
Gross Unrealized Losses	11,961,000	12,581,000
Estimated Fair Value	1,773,634,000	2,121,394,000
Other Equity Securities [Abstract]
Amortized Cost	42,502,000	59,239,000
Estimated Fair Value	42,502,000	59,239,000
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	105	32
Available-for-sale securities in unrealized loss positions for 12 Months or Longer, number of positions	7	6
Total available-for-sale securities in unrealized loss positions, number of positions	112	38
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	166,401,000	29,188,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	48,595,000	50,799,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value	214,996,000	79,987,000
Available-for-Sale Securities, Debt maturities, Gross Unrealized Losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses	1,428,000	158,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	10,533,000	12,423,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	11,961,000	12,581,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost, Due in one year or less	18,343,000
Held-to-Maturity, Amortized Cost, Due in one to five years	269,592,000
Held-to-Maturity, Amortized Cost, Due in five through ten years	275,681,000
Held-to-Maturity, Amortized Cost, Due after ten years	50,989,000
Held-to-Maturity Securities, Amortized Cost, Subtotal	614,605,000
Held-to-Maturity, collateralized mortgage obligations, Amortized Cost, without single maturity date	0
Held-to-Maturity, mortgage-backed securities, Amortized Cost, without single maturity date	17,379,000
Held-to-Maturity, Amortized Cost	631,984,000
Held-to-Maturity, Fair value [Abstract]
Held-to-Maturity, Fair value, Due in one year or less	18,495,000
Held-to-Maturity, Fair value, Due in one to five years	296,031,000
Held-to-Maturity, Fair value, Due in five through ten years	303,861,000
Held-to-Maturity, Fair value, Due after ten years	56,663,000
Held-to-Maturity Securities, Fair Value, Subtotal	675,050,000
Held-to-Maturity, collateralized mortgage obligations, Fair Value, without single maturity date	0
Held-to-Maturity, mortgage backed securities, Amortized Cost, without single maturity date	18,299,000
Held-to-Maturity, Fair value	693,349,000
Available-for-Sale Securities, Amortized Cost [Abstract]
Available-for-sale securities, Amortized Cost, Due in one year or less	40,228,000
Available-for-sale securities, Amortized Cost, Due in one to five years	154,607,000
Available-for-sale securities, Amortized Cost, Due in five through ten years	787,866,000
Available-for-sale securities, Amortized Cost, Due after ten years	456,019,000
Available-for-sale Securities, Amortized Cost, with a single maturity date, Subtotal	1,438,720,000
Available-for-sale government agency collateralized mortgage obligations, amortized cost, without a single maturity date	28,861,000
Available-for-sale government agency mortgage-backed securities, amortized cost, without a single maturity date	240,909,000
Available-for-sale securities, Amortized Cost	1,708,490,000
Available-for-Sale Securities, Fair value [Abstract]
Available-for-sale securities, Fair value, Due in one year or less	40,612,000
Available-for-sale securities, Fair value, Due in one to five years	161,312,000
Available-for-sale securities, Fair value, Due in five through ten years	828,678,000
Available-for-sale securities, Fair value, Due after ten years	458,611,000
Available-for-sale Securities, Fair Value, Subtotal	1,489,213,000
Available-for-sale government agency collateralized mortgage obligations, fair value, without single maturity date	30,636,000
Available-for-sale government agency mortgage-backed securities, fair value, without single maturity date	253,345,000
Available-for-sale securities, Fair value	1,773,194,000
Pooled trust preferred, class A-1 securities, par value	59,200,000
Pooled trust preferred, class A-1 securities, unrealized losses	10,500,000
Percentage minimum for underlying collateral to be in deferral or default concurrently before non-receipt of contractual cash flows (in hundredths)	41.00%
Percentage maximum for underlying collateral to be in deferral or default concurrently before non-receipt of contractual cash flows (in hundredths)	45.00%
U.S. Treasury and agency securities sold due to balance sheet restructuring	398,700,000
Gains on investment securities sold due to balance sheet restructuring	47,800,000
FHLB borrowings retired due to balance sheet restructuring	366,600,000
Early extinguishments costs due to balance sheet restructuring	47,800,000
U.S. Treasury and Agency Securities [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	549,301,000	548,634,000
Gross Unrealized Gains	55,429,000	59,081,000
Gross Unrealized Losses	0	0
Estimated Fair Value	604,730,000	607,715,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	737,785,000	988,217,000
Gross Unrealized Gains	32,035,000	91,040,000
Gross Unrealized Losses	74,000	0
Estimated Fair Value	769,746,000	1,079,257,000
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	3
Available-for-sale securities in unrealized loss positions for 12 Months or Longer, number of positions	0
Total available-for-sale securities in unrealized loss positions, number of positions	3
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	79,672,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value	79,672,000
Available-for-Sale Securities, Debt maturities, Gross Unrealized Losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses	74,000
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	74,000
Obligations of State and Political Subdivisions [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	62,372,000	65,742,000
Gross Unrealized Gains	4,955,000	5,850,000
Gross Unrealized Losses	0	0
Estimated Fair Value	67,327,000	71,592,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	618,853,000	629,883,000
Gross Unrealized Gains	28,775,000	33,070,000
Gross Unrealized Losses	935,000	61,000
Estimated Fair Value	646,693,000	662,892,000
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	87	19
Available-for-sale securities in unrealized loss positions for 12 Months or Longer, number of positions	2	0
Total available-for-sale securities in unrealized loss positions, number of positions	89	19
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	53,061,000	11,503,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	929,000	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value	53,990,000	11,503,000
Available-for-Sale Securities, Debt maturities, Gross Unrealized Losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses	919,000	61,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	16,000	0
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	935,000	61,000
Government Agency Mortgage-Backed Securities [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	17,379,000	20,578,000
Gross Unrealized Gains	920,000	1,079,000
Gross Unrealized Losses	0	0
Estimated Fair Value	18,299,000	21,657,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	240,909,000	253,013,000
Gross Unrealized Gains	12,833,000	16,989,000
Gross Unrealized Losses	397,000	51,000
Estimated Fair Value	253,345,000	269,951,000
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	14	8
Available-for-sale securities in unrealized loss positions for 12 Months or Longer, number of positions	0	0
Total available-for-sale securities in unrealized loss positions, number of positions	14	8
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	30,772,000	14,354,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value	30,772,000	14,354,000
Available-for-Sale Securities, Debt maturities, Gross Unrealized Losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses	397,000	51,000
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	397,000	51,000
Pooled Trust Preferred Securities [Member]
Available-for-Sale Portfolio [Abstract]
Amortized Cost	57,973,000	61,979,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	10,487,000	12,379,000
Estimated Fair Value	47,486,000	49,600,000
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 12 Months or Longer, 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	47,486,000	49,600,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value	47,486,000	49,600,000
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	10,487,000	12,379,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	10,487,000	12,379,000
Government Agency Collateralized Mortgage Obligations [Member]
Available-for-Sale Portfolio [Abstract]
Amortized Cost	28,861,000	32,359,000
Gross Unrealized Gains	1,775,000	1,579,000
Gross Unrealized Losses	0	3,000
Estimated Fair Value	30,636,000	33,935,000
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	4
Available-for-sale securities in unrealized loss positions for 12 Months or Longer, number of positions	1	2
Total available-for-sale securities in unrealized loss positions, number of positions	1	6
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	0	426,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	9,000	1,041,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value	9,000	1,467,000
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	2,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	0	1,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	0	3,000
Corporate Debt Securities [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	2,919,000	2,924,000
Gross Unrealized Gains	61,000	53,000
Gross Unrealized Losses	0	0
Estimated Fair Value	2,980,000	2,977,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	24,109,000	24,136,000
Gross Unrealized Gains	1,217,000	1,265,000
Gross Unrealized Losses	38,000	44,000
Estimated Fair Value	25,288,000	25,357,000
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	1
Available-for-sale securities in unrealized loss positions for 12 Months or Longer, number of positions	0	0
Total available-for-sale securities in unrealized loss positions, number of positions	1	1
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	2,896,000	2,905,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value	2,896,000	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	38,000	44,000
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	38,000	44,000
Marketable Equity Security [Member]
Available-for-Sale Portfolio [Abstract]
Amortized Cost	351,000	351,000
Gross Unrealized Gains	119,000	94,000
Gross Unrealized Losses	30,000	43,000
Estimated Fair Value	440,000	402,000
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 12 Months or Longer, number of positions	1	1
Total available-for-sale securities in unrealized loss positions, number of positions	1	1
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	171,000	158,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value	171,000	158,000
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	30,000	43,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	30,000	43,000
Federal Home Loan Bank Common Stock [Member]
Other Equity Securities [Abstract]
Amortized Cost	21,612,000	38,111,000
Estimated Fair Value	21,612,000	38,111,000
Federal Reserve Bank Common Stock [Member]
Other Equity Securities [Abstract]
Amortized Cost	16,050,000	16,050,000
Estimated Fair Value	16,050,000	16,050,000
Other Debt Securities [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	13,000	16,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	13,000	16,000
Other Equity Securities [Abstract]
Amortized Cost	4,840,000	5,078,000
Estimated Fair Value	$ 4,840,000	$ 5,078,000