BUSINESS SEGMENTS (Details 2) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Segment Reporting Information
Interest income	$ 254,050,000	$ 254,335,000
Charge for funds used	(43,089,000)	(65,025,000)
Interest spread on funds used	210,961,000	189,310,000
Interest expense	(35,132,000)	(45,501,000)
Credit on funds provided	43,089,000	65,025,000
Interest spread on funds provided	7,957,000	19,524,000
Net interest income before provision for loan losses	218,918,000	208,834,000
Provision for loan losses	18,100,000	26,506,000	95,006,000
Depreciation, amortization and accretion	38,669,000	45,066,000
Goodwill	337,438,000	337,438,000	337,438,000
Segment pre-tax profit (loss)	107,795,000	86,580,000
Segment assets	21,749,782,000	21,147,026,000	21,968,667,000
Retail Banking
Segment Reporting Information
Interest income	86,252,000	87,790,000
Charge for funds used	(22,260,000)	(25,588,000)
Interest spread on funds used	63,992,000	62,202,000
Interest expense	(15,548,000)	(22,571,000)
Credit on funds provided	35,040,000	57,345,000
Interest spread on funds provided	19,492,000	34,774,000
Net interest income before provision for loan losses	83,484,000	96,976,000
Provision for loan losses	6,914,000	7,156,000
Depreciation, amortization and accretion	11,933,000	14,700,000
Goodwill	320,566,000	320,566,000
Segment pre-tax profit (loss)	21,759,000	29,533,000
Segment assets	6,638,241,000	6,248,628,000
Commercial Lending
Segment Reporting Information
Interest income	142,966,000	145,335,000
Charge for funds used	(29,749,000)	(40,197,000)
Interest spread on funds used	113,217,000	105,138,000
Interest expense	(7,066,000)	(5,985,000)
Credit on funds provided	3,124,000	3,478,000
Interest spread on funds provided	(3,942,000)	(2,507,000)
Net interest income before provision for loan losses	109,275,000	102,631,000
Provision for loan losses	11,186,000	19,350,000
Depreciation, amortization and accretion	17,133,000	27,101,000
Goodwill	16,872,000	16,872,000
Segment pre-tax profit (loss)	60,428,000	52,236,000
Segment assets	10,079,411,000	9,952,048,000
Other
Segment Reporting Information
Interest income	24,832,000	21,210,000
Charge for funds used	8,920,000	760,000
Interest spread on funds used	33,752,000	21,970,000
Interest expense	(12,518,000)	(16,945,000)
Credit on funds provided	4,925,000	4,202,000
Interest spread on funds provided	(7,593,000)	(12,743,000)
Net interest income before provision for loan losses	26,159,000	9,227,000
Depreciation, amortization and accretion	9,603,000	3,265,000
Segment pre-tax profit (loss)	25,608,000	4,811,000
Segment assets	$ 5,032,130,000	$ 4,946,350,000