INVESTMENT SECURITIES (Details) (USD $)	6 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2013	Sep. 30, 2013 Position	Dec. 31, 2012 Position
Held-to-Maturity Portfolio [Abstract]
Held-to-Maturity, Amortized Cost		$ 617,910,000	$ 637,894,000
Gross Unrealized Gains		41,496,000	66,063,000
Gross Unrealized Losses		2,718,000	0
Fair Value		656,688,000	703,957,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost		1,852,496,000	1,989,938,000
Gross Unrealized Gains		29,387,000	144,037,000
Gross Unrealized Losses		33,231,000	12,581,000
Fair value		1,848,652,000	2,121,394,000
Other Equity Securities [Abstract]
Amortized Cost		52,012,000	59,239,000
Estimated Fair Value		52,012,000	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		7
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		7
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		100,158,000
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		100,158,000
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		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss		2,718,000
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss, Total		2,718,000
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		386	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		394	38
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value		911,826,000	29,188,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value		56,466,000	50,799,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value		968,292,000	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		27,621,000	158,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses		5,610,000	12,423,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses		33,231,000	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		393
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		401
Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		1,011,984,000
Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		56,466,000
Securities, Continuous Unrealized Loss Position, Fair Value		1,068,450,000
Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss		5,610,000
Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss		30,339,000
Securities, Continuous Unrealized Loss Position, Aggregate Loss		35,949,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost, Due in one year or less		8,413,000
Held-to-Maturity, Amortized Cost, Due in one to five years		427,267,000
Held-to-Maturity, Amortized Cost, Due in five through ten years		121,465,000
Held-to-Maturity, Amortized Cost, Due after ten years		48,059,000
Held-to-Maturity Securities, Amortized Cost, Subtotal		605,204,000
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		12,706,000
Held-to-Maturity, Amortized Cost		617,910,000	637,894,000
Held-to-Maturity, Fair value [Abstract]
Held-to-Maturity, Fair value, Due in one year or less		8,465,000
Held-to-Maturity, Fair value, Due in one to five years		463,526,000
Held-to-Maturity, Fair value, Due in five through ten years		120,742,000
Held-to-Maturity, Fair value, Due after ten years		51,209,000
Held-to-Maturity Securities, Fair Value, Subtotal		643,942,000
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		12,746,000
Fair Value		656,688,000	703,957,000
Available-for-Sale Securities, Amortized Cost [Abstract]
Available-for-sale securities, Amortized Cost, Due in one year or less		31,654,000
Available-for-sale securities, Amortized Cost, Due in one to five years		148,887,000
Available-for-sale securities, Amortized Cost, Due in five through ten years		988,465,000
Available-for-sale securities, Amortized Cost, Due after ten years		421,795,000
Available-for-sale Securities, Amortized Cost, with a single maturity date, Subtotal		1,590,801,000
Available-for-sale government agency collateralized mortgage obligations, amortized cost, without a single maturity date		22,996,000
Available-for-sale government agency mortgage-backed securities, amortized cost, without a single maturity date		238,348,000
Available-for-sale securities, Amortized Cost		1,852,145,000
Available-for-Sale Securities, Fair value [Abstract]
Available-for-sale securities, Fair value, Due in one year or less		32,117,000
Available-for-sale securities, Fair value, Due in one to five years		153,709,000
Available-for-sale securities, Fair value, Due in five through ten years		987,770,000
Available-for-sale securities, Fair value, Due after ten years		405,729,000
Available-for-sale Securities, Fair Value, Subtotal		1,579,325,000
Available-for-sale government agency collateralized mortgage obligations, fair value, without single maturity date		23,936,000
Available-for-sale government agency mortgage-backed securities, fair value, without single maturity date		244,899,000
Available-for-sale securities, Fair value		1,848,160,000
Pooled trust preferred, class A-1 securities, par value		57,700,000
Pooled trust preferred, class A-1 securities, unrealized losses		5,300,000
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	648,700,000
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]
Held-to-Maturity, Amortized Cost		540,649,000	548,634,000
Gross Unrealized Gains		38,553,000	59,081,000
Gross Unrealized Losses		2,717,000	0
Fair Value		576,485,000	607,715,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost		888,404,000	988,217,000
Gross Unrealized Gains		2,824,000	91,040,000
Gross Unrealized Losses		13,956,000	0
Fair value		877,272,000	1,079,257,000
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		99,031,000
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		99,031,000
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		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss		2,717,000
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss, Total		2,717,000
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		25
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		25
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value		641,200,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value		0
Available-for-sale Securities, Unrealized Loss Position, Fair Value		641,200,000
Available-for-Sale Securities, Debt maturities, Gross Unrealized Losses [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Gross unrealized losses		13,956,000
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		13,956,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost		540,649,000	548,634,000
Held-to-Maturity, Fair value [Abstract]
Fair Value		576,485,000	607,715,000
Obligations of State and Political Subdivisions [Member]
Held-to-Maturity Portfolio [Abstract]
Held-to-Maturity, Amortized Cost		61,638,000	65,742,000
Gross Unrealized Gains		2,863,000	5,850,000
Gross Unrealized Losses		0	0
Fair Value		64,501,000	71,592,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost		621,802,000	629,883,000
Gross Unrealized Gains		15,352,000	33,070,000
Gross Unrealized Losses		11,159,000	61,000
Fair value		625,995,000	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		206,198,000	11,503,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value		904,000	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value		207,102,000	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		11,125,000	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		11,159,000	61,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost		61,638,000	65,742,000
Held-to-Maturity, Fair value [Abstract]
Fair Value		64,501,000	71,592,000
Government Agency Mortgage-Backed Securities [Member]
Held-to-Maturity Portfolio [Abstract]
Held-to-Maturity, Amortized Cost		12,706,000	20,578,000
Gross Unrealized Gains		41,000	1,079,000
Gross Unrealized Losses		1,000	0
Fair Value		12,746,000	21,657,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost		238,348,000	253,013,000
Gross Unrealized Gains		9,191,000	16,989,000
Gross Unrealized Losses		2,640,000	51,000
Fair value		244,899,000	269,951,000
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		2
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		2
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		1,127,000
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		1,127,000
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		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss		1,000
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss, Total		1,000
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		45	8
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		46	8
Available-for-Sale Securities, Debt maturities, Fair value [Abstract]
Available-for-sale Securities, Unrealized Loss Position, Less than 12 Months, Fair Value		61,198,000	14,354,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value		1,555,000	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value		62,753,000	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		2,508,000	51,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses		132,000	0
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses		2,640,000	51,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost		12,706,000	20,578,000
Held-to-Maturity, Fair value [Abstract]
Fair Value		12,746,000	21,657,000
Government Agency Collateralized Mortgage Obligations [Member]
Available-for-Sale Portfolio [Abstract]
Amortized Cost		22,996,000	32,359,000
Gross Unrealized Gains		940,000	1,579,000
Gross Unrealized Losses		0	3,000
Fair value		23,936,000	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		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		7,000	1,041,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value		7,000	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
Pooled Trust Preferred Securities [Member]
Available-for-Sale Portfolio [Abstract]
Amortized Cost		56,540,000	61,979,000
Gross Unrealized Gains		0	0
Gross Unrealized Losses		5,289,000	12,379,000
Fair value		51,251,000	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		51,251,000	49,600,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value		51,251,000	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		5,289,000	12,379,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses		5,289,000	12,379,000
Corporate Debt Securities [Member]
Held-to-Maturity Portfolio [Abstract]
Held-to-Maturity, Amortized Cost		2,909,000	2,924,000
Gross Unrealized Gains		39,000	53,000
Gross Unrealized Losses		0	0
Fair Value		2,948,000	2,977,000
Available-for-Sale Portfolio [Abstract]
Amortized Cost		24,055,000	24,136,000
Gross Unrealized Gains		930,000	1,265,000
Gross Unrealized Losses		178,000	44,000
Fair value		24,807,000	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		3,038,000	2,905,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value		2,749,000	0
Available-for-sale Securities, Unrealized Loss Position, Fair Value		5,787,000	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		23,000	44,000
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses		155,000	0
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses		178,000	44,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost		2,909,000	2,924,000
Held-to-Maturity, Fair value [Abstract]
Fair Value		2,948,000	2,977,000
Marketable Equity Security [Member]
Available-for-Sale Portfolio [Abstract]
Amortized Cost		351,000	351,000
Gross Unrealized Gains		150,000	94,000
Gross Unrealized Losses		9,000	43,000
Fair value		492,000	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		1	0
Available-for-sale securities in unrealized loss positions for 12 Months or Longer, number of positions		0	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		192,000	0
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Fair Value		0	158,000
Available-for-sale Securities, Unrealized Loss Position, Fair Value		192,000	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		9,000	0
Available-for-sale Securities, Unrealized Loss Position, 12 Months or Longer, Gross unrealized losses		0	43,000
Available-for-sale Securities, Unrealized Loss Position, Gross unrealized losses		9,000	43,000
Federal Home Loan Bank Common Stock [Member]
Other Equity Securities [Abstract]
Amortized Cost		31,187,000	38,111,000
Estimated Fair Value		31,187,000	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]
Held-to-Maturity, Amortized Cost		8,000	16,000
Gross Unrealized Gains		0	0
Gross Unrealized Losses		0	0
Fair Value		8,000	16,000
Held-to-Maturity, Amortized Cost [Abstract]
Held-to-Maturity, Amortized Cost		8,000	16,000
Held-to-Maturity, Fair value [Abstract]
Fair Value		8,000	16,000
Other Equity Securities [Member]
Other Equity Securities [Abstract]
Amortized Cost		4,775,000	5,078,000
Estimated Fair Value		$ 4,775,000	$ 5,078,000