COVERED ASSETS AND FDIC INDEMNIFICATION ASSET (Details 3) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Allowance for loan losses disclosures
Additional advances under shared-loss agreements	$ 466,900,000		$ 466,900,000
Provision for covered loans	(5,179,000)	297,000	(5,705,000)	(2,209,000)
Total allowance allocated to additional advances	5,900,000		5,900,000
Percentage of allowance allocated to additional advances	2.60%		2.60%
Residential
Allowance for loan losses disclosures
Additional advances under shared-loss agreements	11,000,000		11,000,000
Total allowance allocated to additional advances	122,000		122,000
Commercial Real Estate ("CRE")
Allowance for loan losses disclosures
Additional advances under shared-loss agreements	103,300,000		103,300,000
Total allowance allocated to additional advances	3,100,000		3,100,000
Commercial and Industrial ("C&I")
Allowance for loan losses disclosures
Additional advances under shared-loss agreements	319,400,000		319,400,000
Total allowance allocated to additional advances	2,500,000		2,500,000
Consumer
Allowance for loan losses disclosures
Additional advances under shared-loss agreements	33,200,000		33,200,000
Total allowance allocated to additional advances	180,000		180,000
Specific covered loans outside of the scope of ASC 310-30
Allowance for loan losses disclosures
Charge-offs	6,500,000		6,500,000
Provision for covered loans	5,200,000		5,700,000
Specific covered loans outside of the scope of ASC 310-30 | Commercial Real Estate ("CRE")
Allowance for loan losses disclosures
Charge-offs	1,500,000		1,500,000
Specific covered loans outside of the scope of ASC 310-30 | Commercial and Industrial ("C&I")
Allowance for loan losses disclosures
Charge-offs	$ 5,000,000		$ 5,000,000