INVESTMENT SECURITIES (Details) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013 Position	Dec. 31, 2012 Position
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	$ 619,207,000	$ 637,894,000
Gross Unrealized Gains	42,994,000	66,063,000
Gross Unrealized Losses	1,786,000	0
Fair Value	660,415,000	703,957,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	1,708,296,000	1,989,938,000
Gross Unrealized Gains	30,084,000	144,037,000
Gross Unrealized Losses	32,076,000	12,581,000
Fair value	1,706,304,000	2,121,394,000
Other Equity Securities [Abstract]
Amortized Cost	41,001,000	59,239,000
Estimated Fair Value	41,001,000	59,239,000
Held to Maturity Securities In Unrealized Loss Positions, Number Of Positions [Abstract]
Held-to-maturity, Securities in Unrealized Loss Positions, Less Than 12 Months Qualitative Disclosure, Number of Positions	5
Held-to-maturity, Securities in Unrealized Loss Positions, More Than 12 Months Qualitative Disclosure, Number of Positions	0
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	5
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	99,373,000
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value, Total	99,373,000
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	1,786,000
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss, Total	1,786,000
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract]
Available For Sale Securities In Unrealized Loss Positions Less Than 12 Months Qualitative Disclosure Number Of Positions	380	32
Available-for-sale securities in unrealized loss positions for 12 Months or Longer, number of positions	8	6
Total available-for-sale securities in unrealized loss positions, number of positions	388	38
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	615,954,000	29,188,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	51,139,000	50,799,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value	667,093,000	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	22,349,000	158,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	9,727,000	12,423,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	32,076,000	12,581,000
Securities In Unrealized Loss Positions, Number Of Positions [Abstract]
Securities In Unrealized Loss Positions Less Than 12 Months Qualitative Disclosure Number Of Positions	385
Securities In Unrealized Loss Positions 12 Months or Longer Qualitative Disclosure Number Of Positions	8
Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	393
Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	715,327,000
Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	51,139,000
Securities, Continuous Unrealized Loss Position, Fair Value	766,466,000
Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	24,135,000
Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	9,727,000
Securities, Continuous Unrealized Loss Position, Aggregate Loss	33,862,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost, Due in one year or less	8,786,000
Held-to-Maturity, Amortized Cost, Due in one to five years	360,724,000
Held-to-Maturity, Amortized Cost, Due in five through ten years	186,760,000
Held-to-Maturity, Amortized Cost, Due after ten years	48,462,000
Held-to-Maturity Securities, Amortized Cost, Subtotal	604,732,000
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	14,475,000
Held-to-Maturity, Amortized Cost	619,207,000	637,894,000
Held-to-Maturity, Fair value [Abstract]
Held-to-Maturity, Fair value, Due in one year or less	8,860,000
Held-to-Maturity, Fair value, Due in one to five years	390,838,000
Held-to-Maturity, Fair value, Due in five through ten years	194,038,000
Held-to-Maturity, Fair value, Due after ten years	52,056,000
Held-to-Maturity Securities, Fair Value, Subtotal	645,792,000
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	14,623,000
Fair Value	660,415,000	703,957,000
Available-for-Sale Securities, Amortized Cost [Abstract]
Available-for-sale securities, Amortized Cost, Due in one year or less	35,212,000
Available-for-sale securities, Amortized Cost, Due in one to five years	146,830,000
Available-for-sale securities, Amortized Cost, Due in five through ten years	769,425,000
Available-for-sale securities, Amortized Cost, Due after ten years	498,549,000
Available-for-sale Securities, Amortized Cost, with a single maturity date, Subtotal	1,450,016,000
Available-for-sale government agency collateralized mortgage obligations, amortized cost, without a single maturity date	25,222,000
Available-for-sale government agency mortgage-backed securities, amortized cost, without a single maturity date	232,707,000
Available-for-sale securities, Amortized Cost	1,707,945,000
Available-for-Sale Securities, Fair value [Abstract]
Available-for-sale securities, Fair value, Due in one year or less	35,723,000
Available-for-sale securities, Fair value, Due in one to five years	151,709,000
Available-for-sale securities, Fair value, Due in five through ten years	772,445,000
Available-for-sale securities, Fair value, Due after ten years	480,924,000
Available-for-sale Securities, Fair Value, Subtotal	1,440,801,000
Available-for-sale government agency collateralized mortgage obligations, fair value, without single maturity date	26,338,000
Available-for-sale government agency mortgage-backed securities, fair value, without single maturity date	238,687,000
Available-for-sale securities, Fair value	1,705,826,000
Pooled trust preferred, class A-1 securities, par value	58,000,000
Pooled trust preferred, class A-1 securities, unrealized losses	9,500,000
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)	44.00%
U.S. Treasury and agency securities sold due to balance sheet restructuring	648,800,000
Gains on investment securities sold due to balance sheet restructuring	63,800,000
FHLB borrowings retired due to balance sheet restructuring	501,600,000
Early extinguishments costs due to balance sheet restructuring	63,500,000
U.S. Treasury and Agency Securities [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	539,979,000	548,634,000
Gross Unrealized Gains	39,627,000	59,081,000
Gross Unrealized Losses	1,786,000	0
Fair Value	577,820,000	607,715,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	764,446,000	988,217,000
Gross Unrealized Gains	2,553,000	91,040,000
Gross Unrealized Losses	9,129,000	0
Fair value	757,870,000	1,079,257,000
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract]
Available For Sale Securities In Unrealized Loss Positions Less Than 12 Months Qualitative Disclosure Number Of Positions	15
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	15
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	352,566,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value	352,566,000
Available-for-Sale Securities, Debt maturities, Gross Unrealized Losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses	9,129,000
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	9,129,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost	539,979,000	548,634,000
Held-to-Maturity, Fair value [Abstract]
Fair Value	577,820,000	607,715,000
Obligations of State and Political Subdivisions [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	61,826,000	65,742,000
Gross Unrealized Gains	3,196,000	5,850,000
Gross Unrealized Losses	0	0
Fair Value	65,022,000	71,592,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	604,692,000	629,883,000
Gross Unrealized Gains	16,634,000	33,070,000
Gross Unrealized Losses	10,483,000	61,000
Fair value	610,843,000	662,892,000
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract]
Available For Sale Securities In Unrealized Loss Positions Less Than 12 Months Qualitative Disclosure Number Of Positions	314	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	316	19
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	202,253,000	11,503,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	908,000	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value	203,161,000	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	10,449,000	61,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	34,000	0
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	10,483,000	61,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost	61,826,000	65,742,000
Held-to-Maturity, Fair value [Abstract]
Fair Value	65,022,000	71,592,000
Government Agency Mortgage-Backed Securities [Member]
Held-to-Maturity Portfolio [Abstract]
Amortized Cost	14,475,000	20,578,000
Gross Unrealized Gains	148,000	1,079,000
Gross Unrealized Losses	0	0
Fair Value	14,623,000	21,657,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	232,707,000	253,013,000
Gross Unrealized Gains	8,697,000	16,989,000
Gross Unrealized Losses	2,717,000	51,000
Fair value	238,687,000	269,951,000
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract]
Available For Sale Securities In Unrealized Loss Positions Less Than 12 Months Qualitative Disclosure Number Of Positions	46	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	46	8
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	57,788,000	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	57,788,000	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	2,717,000	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	2,717,000	51,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost	14,475,000	20,578,000
Held-to-Maturity, Fair value [Abstract]
Fair Value	14,623,000	21,657,000
Pooled Trust Preferred Securities [Member]
Available-for-Sale Portfolio [Abstract]
Amortized Cost	56,796,000	61,979,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	9,506,000	12,379,000
Fair value	47,290,000	49,600,000
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract]
Available For Sale Securities In Unrealized Loss Positions Less Than 12 Months Qualitative Disclosure 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	47,290,000	49,600,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value	47,290,000	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	9,506,000	12,379,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	9,506,000	12,379,000
Government Agency Collateralized Mortgage Obligations [Member]
Available-for-Sale Portfolio [Abstract]
Amortized Cost	25,222,000	32,359,000
Gross Unrealized Gains	1,116,000	1,579,000
Gross Unrealized Losses	0	3,000
Fair value	26,338,000	33,935,000
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract]
Available For Sale Securities In Unrealized Loss Positions Less Than 12 Months Qualitative Disclosure Number Of Positions	4	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	5	6
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	335,000	426,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	8,000	1,041,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value	343,000	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	2,914,000	2,924,000
Gross Unrealized Gains	23,000	53,000
Gross Unrealized Losses	0	0
Fair Value	2,937,000	2,977,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost	24,082,000	24,136,000
Gross Unrealized Gains	942,000	1,265,000
Gross Unrealized Losses	226,000	44,000
Fair value	24,798,000	25,357,000
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract]
Available For Sale Securities In Unrealized Loss Positions Less Than 12 Months Qualitative Disclosure Number Of Positions	1	1
Available-for-sale securities in unrealized loss positions for 12 Months or Longer, number of positions	1	0
Total available-for-sale securities in unrealized loss positions, number of positions	2	1
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value	3,012,000	2,905,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value	2,747,000	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value	5,759,000	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	54,000	44,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses	172,000	0
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	226,000	44,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost	2,914,000	2,924,000
Held-to-Maturity, Fair value [Abstract]
Fair Value	2,937,000	2,977,000
Marketable Equity Security [Member]
Available-for-Sale Portfolio [Abstract]
Amortized Cost	351,000	351,000
Gross Unrealized Gains	142,000	94,000
Gross Unrealized Losses	15,000	43,000
Fair value	478,000	402,000
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract]
Available For Sale Securities In Unrealized Loss Positions Less Than 12 Months Qualitative Disclosure 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	186,000	158,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value	186,000	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	15,000	43,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses	15,000	43,000
Federal Home Loan Bank Common Stock [Member]
Other Equity Securities [Abstract]
Amortized Cost	20,171,000	38,111,000
Estimated Fair Value	20,171,000	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
Fair Value	13,000	16,000
Other Equity Securities [Abstract]
Amortized Cost	4,780,000	5,078,000
Estimated Fair Value	4,780,000	5,078,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost	13,000	16,000
Held-to-Maturity, Fair value [Abstract]
Fair Value	$ 13,000	$ 16,000