COVERED ASSETS AND FDIC INDEMNIFICATION ASSET (Details 3) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Allowance for loan losses disclosures
Allowance on covered loans	$ 8,665,000		$ 8,665,000		$ 5,153,000
Provision for covered loans	(964,000)	5,179,000	4,848,000	5,705,000
Percentage of allowance allocated to covered loans	3.60%		3.60%
Covered loans accounted for under ASC 310-30
Allowance for loan losses disclosures
Provision for covered loans			2,300,000
Covered loans accounted for under ASC 310-30 | Commercial Real Estate ("CRE")
Allowance for loan losses disclosures
Allowance on covered loans	2,300,000		2,300,000
Specific covered loans outside of the scope of ASC 310-30
Allowance for loan losses disclosures
Provision for covered loans	(772,000)	5,200,000	2,500,000	5,700,000
Additional advances under shared-loss agreements	342,900,000		342,900,000		431,700,000
Charge-offs	0	6,500,000	1,300,000	6,500,000
Allowance allocated to additional advances	6,400,000		6,400,000		5,200,000
Percentage of allowance allocated to covered loans	2.60%		2.60%		2.20%
Specific covered loans outside of the scope of ASC 310-30 | Commercial and Industrial ("C&I")
Allowance for loan losses disclosures
Additional advances under shared-loss agreements	241,500,000		241,500,000		302,300,000
Allowance allocated to additional advances	3,700,000		3,700,000		2,400,000
Specific covered loans outside of the scope of ASC 310-30 | Commercial Real Estate ("CRE")
Allowance for loan losses disclosures
Additional advances under shared-loss agreements	58,400,000		58,400,000		83,400,000
Allowance allocated to additional advances	2,200,000		2,200,000		2,500,000
Specific covered loans outside of the scope of ASC 310-30 | Consumer
Allowance for loan losses disclosures
Additional advances under shared-loss agreements	31,200,000		31,200,000		34,500,000
Allowance allocated to additional advances	376,000		376,000		194,000
Specific covered loans outside of the scope of ASC 310-30 | Residential
Allowance for loan losses disclosures
Additional advances under shared-loss agreements	11,800,000		11,800,000		11,500,000
Allowance allocated to additional advances	$ 161,000		$ 161,000		$ 87,000